försvarets forskningsanstalt foa rapport huvudavdelning 4
TRANSCRIPT
Försvarets Forskningsanstalt
Huvudavdelning 4
172 04 Sundbyberg 4
FOA rapport
C 4OO89-T2(A1)
November 1978
PARTICULATE RADIOACTIVITY, MAINLY FROM NUCLEAR EXPLOSIONS, IN
AIR Aim PRECIPITATION IN SWEDEN MID-YEAR 1975 TO MID-YEAR 1977
Lars-Erik De Geer, Rune Arntsing, Ingemar Vintersved, Jan Sisefsky,
Siv Jakobsson and Jan-Åke Engström
Summary
The National Defence Research Institute runs a network for con-
tinuous sampling of radioactivity in ground level air and in
precipi . tion in Sweden and performs high altitude air sampling
by me- * of aircraft from the Royal Swedish Air Force. The
prese (. /»port describes the revised surveillance program in
effe<t »; nee January 1 1976, discusses the preparation, measur-
ing itu analysis procedures and gives the results of most measure-
ments »cade on samples collected between mid-year 1975 and mid-
yea ' 977. This includes results and discussions on four-week
sämjas of ground level air and deposition collected at seven
locations in Sweden and weekly samples of ground level air
colic'-ted at Kiruna, Grindsjön (near Stockholm) and Ljungbyhed.
All t.gh-altitude samples collected during the two years have
been analysed and reported on, even from times when no fresh
activity was detected. The period covers three atmospheric nu-
clear explosion tests performed by The People's Republic of
China, a low-yield test on January 23 1976, a medium range yield
test on September 26 1976 and a high-yield test on November 17 1976.
These three tests are discussed in terms of such factors as the at-
mospheric behaviour of the debris cloud, fractionation and particle
properties of the debris and of neutron activation products detect-
ed. One strong sample collected nine days after the November 17 1976
thermonuclear explosion was measured extensively during more
than 3 year and was used to construct a mass-yield curve which
is compared with mass-yield curves for different monoenergetic
neutrons incident on 2 3 8U. On some occasions activities were
detected that did not derive from any known nuclear explosions
test. This is discussed in the last chapter, parts of which have
been published elsewhere but which is included here to give a full
account of the two years covered by this report.
Uppdragsnummer: TR 81
Sändlista: Fst, FHS, MHS, SjvS, Cfs, SkyddS, UD, FÖD, MVC, SMHI,
AE, SSI, Radiofysiska Inst Lund, Göteborg, Linköping, Stockholm,
Umeå, Statens Naturvårdsverk, LHS, VHS, CTH, KTH, Riksdagsbibi,
FOA 1, FOA 2.
CONTENTS
Introduction 5
Surveillance program 8
Sampling 9
Ground level air 9
Precipitation 12
High altitude air 12
Preparation of y-ray samples 13
Ground level air 14
Precipitation 15
High altitude air 16
Measurements and analysis of y-ray samples 16
Ge(Li)-detector and data aquisition system 16
Counting 16
Detector efficiencies 17
Spectra evaluation 17
Error analysis 18
Detection limits 19
Particle studies 22
Four-week samples of ground level air and deposition 23
Ground level air 23
137Cs 23
Comparison between stations 24
Deposition 26
137Cs 26
Comparison of the 55Zr/137Cs activity ratio in ground 29
level air and in precipitation
Weekly samples of ground level air at Kiruna, Grindsjön 32
and Ljungbyhed
High altitude samples 36
The Chinese low-yield explosion of January 23 1976 37
The Chinese medium range yield explosion of September 40
26 1976
Bulk samples 40
Particle properties 43
Neutron reaction products 46
The Chinese high-yield explosion of November 17 1976 49
Fractionation and particle properties 50
The stratospheric sample collected on November 26 1976 52
Mass chain yields
133Xe-diffusion
95Nb/95Zr-dating
Symmetric fission probability
Low Z activation products
High Z activation products
Anomalous activities
239Np, "Mo, 1 3 1 I , 1It0Ba
75Se
References
Appendix I.
54
56
57
57
59
59
62
62
68
69
69
71
77
87
89
Four-week average ground level air concen-
trations and deposition values Jan 1976 -
June 1977. 8 tables.
Appendix II. Quarterly deposition of 137Cs 1961-1977.
1 table.
Appendix III. Weekly average ground level air concentra-
tions. July 1975 - June 1977. 3 tables.
Appendix IV. Activity ratios in ground level air at Grind-97
sjön Aug 1972 - June 1977 18 figures.
Appendix V. High altitude air concentrations. July 1975--107
June 1977. 1 table.
Appendix VI. Ge(Li)-spectra measured of the November 26
1976 sample at debris ages of 13.1, 50.2,
174 and 356 days. 1 figure in four parts.
INTRODUCTION
Radioactivity in Swedish ground level and high altitude air and
in precipitation has been collected and measured by the National
Defence Research Institute since the mid 1950's. Monthly concen-
tration averages in air of yemitting radionuclides at ground
level and in precipitation have been measured on NaI(Tl)-detec-
tors and have been reported on over the years (Lindblom 1965,
Lindblom 1969, Bernström 1969, Bernström 1974, Bernström 1978).
Corresponding results of the high-altitude sampling have been
presented in different papers on specific nuclear explosion tests
and on more basic aspects of nuclear fallout (e.g. Persson 1966,
Persson et al 1969, Sisefsky et al 1970, Edvarson et al 1965,
Edvarson et al 1966).
Since 1967 the routine NaI(Tl)-setup has been increasingly support-
ed by high resolution Ge(Li)-detectors. Weekly Ge(Li)-measurements
of ground-level air from three sampling stations have been summa-
rized up to mid-year 1975 (Arntsing et al 1977) and Ge(Li)-measure-
ments of mostly high-altitude samples have been published in connec-
tion with reports dealing with single atmospheric and venting under-
ground nuclear explosions (Persson et al 1971, Sisefsky et al 1970,
Sisefsky et al 1971, De Geer et al 1977, Persson 1969, Persson 1971,
Eriksen 1972).
Fresh debris has been analysed with respect to radioactive par-
ticles by means of reversal autoradiograpHic methods (Sisefsky
1973). The particles have been classified according to such para-
meters as particle size distribution, specific activity, particle
form and particle colour. The results of such studies have been
included in several of the references given above and have been
the main issue of e.g. Sisefsky 1961, Sisefsky 1964, Sisefsky 1965,
Sisefsky 1966 and Sisefsky 1967.
A new program for sampling and measurement was introduced in Janu-
ary 1976 when the old NaI(Tl)-detector system was taken out of
operation. Before that date high-altitude samples and ground level
air samples from three out of eight stations were regularly ana-
lysed by means of Ge(Li)-detectors. Since the beginning of 1976
all samples (ground level air from all stations, precipitation
and high altitude air) have been analysed using the Ge(Li)-system.
The present report gives an account of the current surveillance
program and the results of Ge(Li)—measurements and particle studies
carried out between mid-year 1975 and mid-y^ar 1977. The Nal(Tl)-
results from the second half of 1975 of monthly ground level air
and precipitation samples are reported elsewhere (Bernström 1978).
During the period January 1975 to June 1977 three atmospheric nu-
clear explosions were carried out in the northern hemisphere by the
People's Republic of China at the Lop Nor test site (40°N 90°E)
in Sinkiang. The first of these tests, performed on January 23
1976, had a yield in the low-yield range (<20 kt) and the second,
on September 26 1976 had a yield in the range of 20-200 kt (USERDA
1976). The third one with a yield of about 4 Mt (USERDA 1976), up
to then the largest one in China, was conducted on November 17 1976.
All three explosions were set off at about 2 pm local time (0600
GMT). No other atmoshpheric nuclear tests were performed in the
world during the period of interest and no particulate activity
detected in Sweden could be associated with any release to the
atmosphere from any of the 77 underground tests carried out during
the same time (January 1975 - June 1977) by China (1), France (8),
Great Britain (1), the Soviet Union (33) and the United States (34)
(Zander et al 1978). One of the Soviet underground thermonuclear
explosions at Novaya Zemlja (Oct 21, 1975) is, however, suggested
as the cause of an increase in the atmospheric HT-concentration at
a tritium sampling station operated by this laboratory at Hagfors
(Bernström 1977). The main sources for the particulate radioacti-
vity presently reported are consequently the 1976 Chinese nuclear
explosions and the stratospheric inventory built up by earlier at-
mospheric high yield tests. One nuclide reported is produced by
cosmic ray interactions in the atmosphere (7Be) and some radio-
nuclides were detected on a few occasions when they could not be
due to any known nuclear explosion.
SURVEILLANCE PROGRAM
The surveillance program effective before January 1976 has been
described in earlier reports (Arntsing et al 1977, Bernström 1974,
Bernström 1978). Here only the revised program introduced in Janu-
ary 1976 will be accounted for. The aim of the surveillance can
be formulated in the following poincs:
a) to follow continuously, with a time resolution of about
one month, the concentration of yeniitting radionuclides
in the air close to the ground and in precipitation in
Sweden at a reasonably tight network of sampling sta-
tions,
b) to follow continuously, with a time resolution of one
week, the concentration levels of Y~emitting radionu-
clides in the air close to the ground at one station
in the south of Sweden, at another one in mid-Sweden
and at a third one in the north,
c) to run one station for ground level air not far from
the main laboratory with optimal equipment and to mea-
sure weekly samples from there with the best detectors
available at the laboratory,
d) to check, with a time resolution of one week, all
samples of ground level air for short-livrd activi-
ties,
e) to be able to isolate and examine single "hot" particles
and to have collected material available for other spe-
cial studies when needed,
f) to examine, once or twice a month, the concentration
levels of y-emitting radionuclides in the air at high
altitudes (around the tropopause), and
g) to substantially increase the frequency of high alti-
tude sampling at times when fresh debris is expected.
The objective of a is to get the necessary basic data for estima-
ting the exposure of the Swedish population to fallout from nu-
clear tests. The reason for b and a is to detect violations of
the 1963 Partial Test Ban Treaty (which forbids the signature
powers to perform nuclear explosions that introduces any radio-
activity outside their own borders) but also to detect reasonably
small atmospheric traces from any other use or production of ra-
dioactive materials. To avoid overlooking any relatively strong but
short-lived activity at the stations only measured monthly, the
filters from these are checked qualitatively each week according
to d. The objectiv of e, / and especially g is mainly to study
the parameters of different individual nuclear explosions in the
atmosphere, and to study in general the radiation and particle
properties of nuclear debris and the mechanisms for its atmos-
pheric transport. Since the Partial Test Ban Treaty came into
force in 1963 these studies have been performed almost exclusive-
ly on the 18 nuclear explosion tests carried out in the atmos-
phere (up to mid-year 1977) by the People's Republic of China.
SAMPLING
To fulfill the objectives given above, eight ground level stations
have been established in the country (Fig 1), and aircraft from
the Royal Swedish Airforce base at Linköping 175 km soutwest of
Stockholm, have been equipped with filtering devices (normal flight
route indicated in Fig 1). In Fig 2 photographs are shown of the
Grindsjön and Östersund ground level stations.
Ground level air
All stations but the one at Grindsjön collect airborne dust on a
0.57m x0.57m glass fiber filter which is changed every Monday,
Wednesday and Friday. The glass fiber filter used is manufactured
10
50
56
100 200
Fig 1. Swedish stations for sampling of radioactivity inground level air and precipitation, operated by the NationalDefence Research Institute. The most common route taken bythe high altitude sampling aircraft is indicated by theshaded area.
1
11
Fig 2. The Grindsjön (top) and Öster-sund (bottom) ground level stations.
12
at this institute and is denoted FOA-1-484 in the WHO-summary on
filter media (Suschny 1968). The air is blown through the filter
by a high capacity centrifugal pump with a rate of about 26000m3/
day, corresponding to a linear flow rate of 1 m/s. At Grindsjön
three O.52mx0.52m glass fiber filters are changed every Monday.
Around 72000 m3 of air is filtered e?ch day corresponding to a
somewhat lower flowrate than at the other stations. Grindsjön is
the station intended to satisfy point a above.
Precipitation
All the stations except the oiu; at Hagfors nre equipped with large
funnels (diameter 2m) for precipitation sampling. Wh?n necessary,
the funnels are heated to melt the snow. The water passes through
an ion exchange unit which is mounted inside the house, below the
funnel. This unit consists of one layer of glass fiber to collect
the particulate matter and two 20 ml layers of anion and cation ex-
changers to collect the dissolved activities. The ion exchange
units are changed every Monday if the precipitation during the
previous week exceeded 1 mm.
High altitude air
The filtering devices, three of which are mounted under each wing
of a J32 Lansen fighter, can be opened and closed by the pilot
during flight (Edvarson 1957, Edvarson et al 1960). The filter
size in each is 0.58mx0.32m and during a normal flight with the
devices open for 20 minutes 80 to 200 kg of air is sampled by
each filter. The sampling rate depends on altitude and speed of
the aircraft. When no fresh debris is anticipated flights are
performed once or twice a month with three devices open 1 km above
the tropopause and the other three open 1 km below, or with all
six devices open at 14 km. Under each wing rwo devices are loaded
with glass fiber filters for y-ray spectroscopy studies and the
third one with an organic and dissolvable filter (Mic-osorban*^)
aimed at delivering material for particle examinations and other
13
studies. When there is reason to expect fresh debris the flights
are performed almost daily and the normal loading and flying alti-
tudes are then often changed considerably.
PREPARATION OF Y~RAY SAMPLES
All measurements on the Ge(Li)-detectors are made with two main
counting geometries. The first one consists of a 14 mm high, 64mm
diameter, disc that fits the top of a Ge(Li) endcap. The second
one is a variation of the "Marinelli" type geometry consist-
ing of the same disc as above on top of the detector and five
bricks (50mmx80mm x14mm) placed around the detector circumfer-
ence (Fig 3). The discs and bricks are contained in plastic boxes
of the given dimensions. The first geometry is used for weekly
samples of ground level air and high altitude samples and the
second one for four-week pools of ground level air. The four-
week precipitation pools are measured in the second geometry with
the disc and only one brick filled.
Fig 3. Counting arrangement for one discand five bricks.
14
Ground level air
One-week samples are measured from Kiruna, Grindsjön and Ljungby-
hed, and four-week samples are measured from all but the Grind-
sjön station. Fig 4 shows how the 12 filters from one station
WEEK 1
WEEK 2
WEEK 3
WEEK 4
MON-WEO
A—»
D
CB
- »
_p_.ALL 12
ALL 12
C -SECT
D -SECT
WED-FRl
71 •
• • - - 1
!
• " " rI
FRI -•MON
1 ' ""
- »
-1
|i
ONE-WEEK
SAMPLES
o or n —» D
MiK) (brick)
1o or n —» D
1Q or p| , []
1Q or p| _ > p|
1
. n
i
FOUR-WEEK SAMPLE
Fig 4. Preparation of y-vay samples from filters from onestation (not Grindsjön) during a four week cycle. The fil-ters are cut into four parts which go into different samplesas shown. Section B is used for particle search and/or otherspecial studies when needed (e.g. for increasing the timeresolution). The Kiruna and Ljungbyhed samples are measuredquantitatively each week in the disc geometry and the fil-ter mass is then redistributed to a brick for the four-weekmeasurement. One-week samples from the other five stationsare only checked qualitatively for short-lived activitieswith a brick on top of the detector.
15
(not Grindsjön) during a four-week cycle are cut and made into
different samples. Since the counting efficiency is not the same
for the disc and the brick positions around the detector the scheme
is such that in the four week geometry each filter makes a fixed
contribution to each position (disc 12.5 %, bricks 62.5 %, 25 %
is saved).
To minimize the time delay between sampling and counting and to
optimize the duty cycle of the detection system, filters from
different stations are pooled during different four-week periods.
From Grindsjön 60 % of the filter area available from each week
is pressurized into the disc geometry, the rest being saved for
other purposes.
The capacity of the pumps and the scheme of sample preparation re-
sult in that a Grindsjön weekly disc contains particulate matter
from around 300000 m3 (~375000 kg) of air, that weekly discs or
bricks from the other seven stations contain material from around
90000 m~ (~112000 kg) of air and that a four-week pool corresponds
to about 550000 m3 (~680000kg) of air.
Precipitation
The filter mass and the two ion exchanger fractions from each pre-
cipitation unit used during a four-week period (the same as for
the corresponding four-week pool of air samples) are ashed by
keeping the masses at 300 C for some days. The ash then fills one
disc and one brick container of the same type as used for the
pressurized air filters.
The ashing procedure has been checked for activity loss by ana-
lysing a number of samples containing both fresh and old debris
before and after the process. It was then found that up to 30%
of the 131I activity could disappear while less than 10% of all
other radionuclides present in the samples was lost during the
preparation.
16
High altitude air
From a "normal" flight with two glass fiber filters exposed 1 km
above the tropopause and two 1 km below, each set of two filters
is pressed into a disc and measured separately. For a flight
at one single altitude three or four glass fiber filters are used
in the sample. In the first case each sample corresponds to about
250 kg of air and in the second case around twice that value.
MEASUREMENTS AND ANALYSIS OF y-RAY SAMPLES
Ge(Li)-detector and data aquisition system
During the two years presently of interest two 10%-efficiency,
2.0 keV FWHM ORTEC VIP-detectors and two 2O7=-efficiency, 1.9 keV
FWHM closed end Princeton Gammatech crystals have been employed.
All detectors are placed in 10 cm lead shields. One of the Prince-
ton detectors is surrounded by a 0 20cm * 30cm NaI(Tl)-annulus v;ith
a fl> 7cm x10cm back detector to supress the compton events and to
reduce the background. When the guard has been in operation both
the supressed and the normal spectrum have been stored to facili-
tate the quantitative determinations.
The data aquisition and handling are carried out by means of a
32K memory PDP-11/10 computer connected to a 32K memory PDP-15
machine equipped with an on-line display with light pen, five
DEC-tape units and an incremental plotter. An interface for 4
8K-ADC:s, with the possibility of supplying both computers with
data, is used. However, normally all data aquisition is taken
care of by the PDP-11.
Counting
The energy region covered is as a standard 0 - 2048 keV in 4096
channels, with the lower cut-off set around 25 keV. The weekly
air filter samples from Kiruna, Grindsjön and Ljungbyhed are
measured for 4000 minutes and the four-week air filter pools for
about 2500 minutes. The intention is to measure the precipitation
17
pools for 2500 minutes but the detector availability has often not
allowed for more than half of that time. The qualitative checks
are performed during spare times ranging between 100 and 1000
minutes. The counting time for the high altitude material is
normally about 1000 minutes but varies at times of fresh debris
considerably with the strength of the individual samples.
Detector efficiencies
The detector efficiencies are determined with a method mainly
based on the long-lived l66mHo-activity, as described in a pre-
vious report (Eriksen 1975). The low energy calibration down to
35 keV has been improved by using a lttl*Ce source. In the calibra-
tion procedure corrections are made for the coincidence summing
due to the high efficiency detectors and the close counting geo-
metries used. In the analysing phase care is taken to select gamma
rays essentially free of coincidence problems. For most isotopes
present in nuclear debris such gamma rays are available and in
cases when not, corrections are made that lower the errors due
to coincidence summing well below other errors present.
To check the efficiency calibrations the laboratory participated
in the 1976 IAEA intercomparison test (Tugsavul et al 1976). For
the five y-emitters (5i*Mn, 106Ru, I 3 1 I , 137Cs and ^ C e ) present
in the test filters the RMS deviation from the true values was
less than 3.6% if the IAEA input values are considered true and
less than 5.5 % if the overall laboratory means were considered
the true ones.
Spectra evaluation
All spectra are analysed by a peak searching and gaussian shape
fitting code written for the PDP-15 with the facility of visually
checking the quality of the fits on the display. The program is
an exceedingly rewritten version of the commercially avaialble pro-
gram GASPAN (Barnes 1968). The y~ray intensities obtained from
18
the search-and-fit code are processed by an isotope identifica-
tion program. In a final step the concentration and deposition
values are calculated. In addition a manual control is carried
out on the display of the portions of the spectra whe e no peaks
have been established by the program. For the very weak peaks then
found, a simple integration procedure is employed.
Error analysis
Gamma-peaks well above the detection limit give a maximum overall
counting and analysis error slightly above the 5% introduced by
the efficiency uncertainties of the Ge(Li)-spectrometer (Eriksen
1975). This estimate is also well confirmed by the IAEA inter-
comparison. When the true signals diminish to the detection limit
of the measuring procedure and further on to the decision limit,
the errors will of course increase. The uncertainties introduced
into the ground level air concentrations by the air flow determi-
nations can be estimated to be less than 10 %, giving a maximum
total error in the concentration values of approximately 15%, for
activities well above the detection limits.
The total errors in the deposition values deduced from the pre-
cipitation measurements can in the same way be estimated tobeless
than around 30 % for a four-week period. One part of this error
derives from the fact that when the last ion exchange unit in a
four-week pool is dismounted there can sometimes be some water
left unprocessed in the funnel that will be assigned to the next
four-week pool. As a consequence this error will be reduced when
an average is formed for a longer period. The amounts of precipi-
tation reported (but not used to calculate the deposition) have
in some cases been found to be up to 25% below the values given
by nearby meteorological stations.
For high altitude air samples the absolute concentration levels
can be in error by a factor of up to two, due to the difficulties in
calibrating the sampling efficiencies. The filtering devices are de-
19
signed for sampling at an altitude of 12 km at a speed of 0.8
Mach, while the calibrations were performed in a wind tunnel at
ground level air density and at a corresponding speed of 0.3 Mach.
However, the relative error, when comparing different flights of
about the same altitude, should remain less than 20 %. Most of the
high altitude results, especially when connected to specific nu-
clear explosions, are discussed in terms of fractionation factors
or relations between different radionuclides in a sample. The
amount of air is then of no interest, and the errors reduce to
the counting and analysis errors discussed above. In that case
also a large part of the systematic error in the counting process
can be ignored as it is connected with the absolute determination
of the detector efficiency. The same applies to the activity
ratios presented in some figures below for the weekly ground
level air samples.
An additional source of error is the uncertainty in the Y/3~
branching factors for the radionuclides reported. These errors
are normally small and are not of primary interest to the dis-
cussion, if stated which factors arc used. At this laboratory
most Y~ray energies and y/3~branching factors are taken from
the compilation by Bowman et al. (Bowman et al. 1974).
Detection limits
Different limits can be stated for the qualitative detection
and quantitative determination of radionuclides. L.A. Currie
(Carrie 1968) defines three limiting levels: the decision limit
LQ at which one may decide whether or not the result of an analy-
sis indicates detection, the detection limit LD at which a given
analytical procedure may be relied upon to lead to detection,
and a determination limit LQ at which a given procedure will be
sufficiently precise to yield a satisfactory quantitative esti-
mate. It can be shown that the peak search procedure employed
has a decision limit of L^ = t'W-v > with t being the critical
20
value of a Student's t-test performed by the program, w the FWHM
of the photo peaks expressed in channels (with the restriction
that 2.7,<w(<4.5) and b the background count per channel. With
t normally set to 5 and w»3.5 a decision limit of ~ 18 Vi re-
sults.
The manual check performed after the automatic analysis has been
found by experience to lower the decision limit by approximately a fac-
tor of four. If the risk for detection without true signal (error of
the first kind) and the risk for non-detection when there is a
true signal (error of the second kind) ars both accepted to be
5%, Currie shows that the detection limit Ln is equal to 2.71
+2LQ which for b > 0 and the manual control included gives LQ w
10\/b.
Based on this criterium the computer calculates detection limits
Lp for each nuclide searched for, but not found in the spectrum.
These limits depend via b on the composition of radionuclides
present, the amount of air or precipitation sampled, the time
delay between sampling and counting and the counting time. The
detection limits in individual samples are not reported but
typical values for some standard measurements are given in
Table 1. The limits are expressed as minimum and maximum limits
in measurements performed according to the standard procedure
during the period July 1975 - June 1977. This period includes
both samples with rather old debris in low concentrations, and
fresh debris in high concentrations, which results in maximum
limits of about 5-10 times the minimum limits. As the maximum
limits normally refer to fresh high concentration samples, when
most explosion debris nuclides are present well above the detec-
tion limits, it is the minimum values that apply to the interest-
ing situation when the actual concentrations approach the detec-
tion limits.
21
5*Mn
09y
?<Zr
' •^Ru
• 'Ce R u
" sSb131i
n:Te
137Cs
"•»Ba
"••Ce
' " C cU 7 N d
= 37U
"39 N p
A
aCi/k?,
28 - 280
1.9 - 11
2.0 - 11
3.5 - 44
16 - 150
2.3 - 35
18 - 210
8.8 - 77
6.5 - 44
11 - 120
2.0 - 20
2.6 - 23
4.4 - 27
16 - 100
16 - 200
7.5 - 47
31 - 180
160 - 2000
B
aCi/kg
72 - 500
6.7 - 27
'..1 - 22
1 1 - 6 5
40 - 250
6 . 1 - 5 6
58 - 410
20 - 130
14 - 92
39 - 250
6.6 - 40
9.0 - 41
8.4 - 52
34 - 190
43 - 400
15 - 90
60 - 360
620 - 3500
C
aCi/ttg
52 - 210
2.5 - 4.2
2.6 - 3.3
5.4 - 24
3200-12000
3.3 - 30
22 - 140
9.1 - 45
33 - 170
930 - 4900
2.5 - 12 .7.8 - 15
8.0 - 2319 - 59
36 - 130
8.0 - 26
240 - 870
86000 -440000
D
fCi/kg
39 -
4.1 -
4.2 -
6.9 -5.2 -
3.6 -
36 -
11 -4.9 -7.4 -
4.2 -
4.3 -4.8 -
19 -
18 -
9.0 -
18 -
57 -
E
pCi/m2-4 weeks
3 - 2 0
0.46 - 0.67
0.55 - 0.60
0.90 - 2.6
80 - 22000.52 - 2.3
3.7 - 16
1.1 - 5.9
2.5 - 2660 - 950
0.39 - 1.51.8 - 3.3
0.68 - 1.5
1.8 - 6.7
2.6 - 17
0.63 - 2.5
13 - 130
2100 - 92000
Table 1. Ranges of detection limits for some standardized samp-ling and counting procedures.
A: Ground level air weekly sample (~ 375000 kg)Disc on top of det. Counting 4000 min.
B: Ground level air weekly sample (~110000 kg)Disc on top of det. Counting 4000 min.
C: Ground level air four week sample (~680000 kg)Disc+ five bricks. Counting 2500 min
D: High altitude air single sample (~200 kg)Disc on top of det. Counting ~1000 min.
E: Deposition four week sampleDisc+one brick. Counting ~2000 min.
No maximum detection limits are given for the high altitudesamples as the very strong fresh debris samples generate excess-ively high detection limits which are or no interest.
If the requisite relative standard deviation is less than 10 %,
Currie shows that LQ - 5O'|l+(l+b/25)1M which for b>100 yields
10\Zb"<Lq<17Vb" i.e. LqwLp. As a consequence of this and of Table 1
all detected ground level air concentrations below 10 aCi/kg and
deposition values below 0.1 pCi/m2«4 weeks are reported only as
<10 aCi/kg (<0.01 fCi/kg) and <0.1 pCi/m2 «4 weeks, respectively.
22
PARTICLE STUDIES
The reversal autoiadiographic method used to isolate and study
single particles is described by Sisefsky elsewhere (Sisefsky
1973).
23
FOUR-WEEK SAMPLES OF GROUND LEVEL AIR AND DEPOSITION
The four-week average ground level air concentrations and deposi-
tion values of the radionuclides detected in the four-week samples
from Kiruna, Ljungbyhed, Gothenburg, Stockholm, Grindsjön (deposition
only), Hagfors (air only), Lycksele and Östersund are given in
tables in Appendix I for the period from January 1976 to June 1977.
The order of the tables is due to the successive starting weeks
beginning with Kiruna on the first of December 1975.
GROUND LEVEL AIR
The ground level air concentrations of 137Cs are plotted in Fig 5
for the Stockholm station for the period September 1957 to mid-
year 1977.
0.0)
Fig 5. 137Cs in ground level air in Stockholm 1957-1977.
The lowest level during this period was reached in the winter
1976-77. The level subsequently rose again due to the usual spring peak
phenomenon and the Chinese high yield explosion of November 17
1976.
24
Comparison between stations
To compare on a longer time scale the radionuclide concentrations
at the different stations the activities have been integrated
between January 1 and September 30 1976 and between October 1
1976 and June 30 1977. The first 9 month period was mainly char-
acterized by old debris, the last preceding large injection being
the Chinese explosion of June 1974. During the second 9 month
period fresh debris arrived from the September 26 and November 17
1976 explosions. The time integrated tctivities are given in
Tables 2 and 3 in percent of the all station average.
IntegratednetivityconcentrationkBqs Kiruna Lycksele Östersund Hagfors Stockholm Gothenburg Ljungbyhed
""Mo
175;" ' I
i<»o Ba
~'~Nd
47<0.004
0.006
0.0080.240.0610.015
0.190.0340.0130.40
0.011
84
44
248992
768
2082
71
101
67
91
31
100
99
130
203
4710398
1004440102
1ft8991
87181388
68102104480
100625593
26712613141
K'fl353290131
86 63 102 142
99
143
129959269
102107147102
118
95
113
1299692
110
10710813597
118
Avr>rar,e percentage ofnurlides vith h.ilf-l ives lonppr than fourweeks (underlined). 65 83 65 92 172 114 109
Table 2. Integrated activity concentrations as percentages of theaverage of seven sampling stations, and for each station the averagepercentage for nuclides with half-lives longer than four weeks(1 kBqs = 106/37 pCis). The integral is performed between January 1and September 30 1976.
25
IntegratedactivityconcentrationkBqs
7Be 33^Mn 0.03388Y 0.022^Zr 4.8
1"R° 3.0)°'Ru 1.6|2SSb 0.15l 3 l I 0.60132Te ."7Cg 0.26"^il 1.6'"'Ce 2.61 ' • ' tp . 2 Q1<t7Nd 0.48'"Eu 0.023237U 0.056
Average percentage ofnuclides with lialf—lives longer than fourweeks (underlined).
Kiruna
95686872
727678',7
-756570736 85763
73
Lycksele
97928685
838382
128-
84107
8983
12972
234
85
Östersund
92809381
83838371-
806574826675
117
82
Hagfors
9110310896
881C9113
47
995478
10746
134
-
102
Stockholm
126128121135
130127126169
121136134127174150
:
130
Gothenburg
84908095
1028383
117
111136113
87118
95
-
93
Ljungbyhed
115139144136
142139135101
13013714214199
117286
135
Table 3. Integrated activity concentrations as percentages of theaverage of seven sampling stations, and for each station the averagepercentage for nuclides with half-lives longer than four weeks(1 kBqs = 106/37 pCis). The integral is performed between October 11976 and June 30 1977.
In order to provide an index of the relative amount of radionu-
clides in air on each location the average percentages for iso-
topes with half-lives longer than four weeks are also given. From
Table 3 we can conclude that between October 1 1976 and June 30
1977 the concentrations were 15-25 % lower than the average at
Kiruna, Lycksele and Östersund, around average at Hagfors and
Gothenburg and about 30 % higher than average in Stockholm and at
Ljungbyhed.
This concentration gradient pointing mainly south is also clear
for the preceding 9 months (Table 2), even if the picture is then
somewhat obscured for the nuclides with half-lives less than about
100 days, due to their being present in the period only during a
very short time after the weak January 23 1976 Chinese explosion.
A corresponding comparison can be made for a longer period if the
number of nuclides is reduced. Considering 95Zr, 106Ru, 125Sb,
26
137Cs and lttl*Ce (Bernström 1978) the activities can be integrated
for all stations between January 1 1972 and June 30 1977. This is
done in Table 4.
IntegratedactivityconcentrationkBqs
95Zr 16.5106Ru 12.512sSb 1.76137Cs 3.35'""Ce 27.6
Average percentage
Kiruna
8692979090
91
Lycksele
9294939493
93
Östersund
97102102103101
101
Hagfors
94100919598
96
Stockholm
134126129130131
130
Gothenburg
8174777778
77
Ljungbyhed
116112111110109
112
Table 4. Integrated activity concentrations in percent of the averageof seven sampling stations, and for each station the average percent-age for the given nuclides (1 kBqs = 106/37 pCis). The integral isperformed between January 1 1972 and June 30 1977.
As would be expected,the integrated activities for different sta
tions tend to approach each other when the time interval is in-
creased. Stockholm is, however, still 30% above average while
Gothenburg is now 20% below.
DEPOSITION
The 137Cs activity is an easy-to-detect indicator of the deposi-
tion of long-lived debris from nuclear explosions in the atmos-
phere and is furthermore the main contributor to the global dose
commitment delivered by such explosions. As a consequence 137Cs
has been in focus since large scale nuclear testing started in
the mid 1950's. Deposition values of 137Cs have been continuously
measured at this laboratory since 1953 and to give a picture of
the past and present the results are summarized for one location
in the form of yearly averages in Fig 6 (Low et al. 1957, Lind-
blom 1959, Lindblom 1969, Bernström 1978). Also given in the same
figure is the four-week variation during the last one and a half
years.
27
JO-
15-
10-
i
Ml tel Ml STI 9*1 StlMCl «1| 121 (31 Ml (SI Ml *H Ml Mi
Fig 6. Yearly deposition of 137Cs in Stockholm 1953-1977. (The 1958-61 values are Swedish average values as reported by Lindblom 1969).The inset gives the four-week deposition in Stockholm for the pe-riod presently reported of.
The Chinese November 17 1976 4 Mt explosion raised the deposition
rate more than ten times, but that is still only 8 % of the maxi-
mum yearly average in Stockholm (1963) and only 2 % of the maxi-
mum monthly average ever measured in Sweden (Gothenburg August
1963, Lindblom 1965, Bernström 1978). Integrating the curve in
Fig 6, taking into consideration the radioactive decay, yields
the accumulated deposition of 137Cs in Stockholm since 1953.
This is done in Fig 7.
28
Fig 7. Cumulative deposition of ^ 7 C s in Stockholm (based onthe deposition rates of Fig 6). The dashed bransch indicatesthe expected cumulative deposition if no atmospheric nucleartests had occurred after 1963.
As no large amounts of debris were globally distributed betore
1953 (the first thermonuclear test occurred on October 31 1952 at
Eniwetok Micronesia) the lower limit can be extended to an arbi-
trary date before 1953. The accumulated deposition in the be-
ginning of the 1970's of around 66 mCi/km2 can be compared to
the 64.2±2.2 mCi/km2 measured during the same years in the moss,
humus and soil layers of a southern Sweden spruce and pine for-
est (Mattsson et al. 1975).
The dashed curve indicates what accumulated 137Cs deposition would
have been expected if no nuclear explosion test had been performed
by the People's Republic of China. The curve is estimated by extract-
ing a stratospheric half residence time of about 1 year from the
decay of the 1963 peak value in Fig 5.
29
In Appendix II the quarterly depositions of 137Cs at all sampling
stations are summarized from the end of 1961 to mid-year 1977. To
correspond to the ground level air data in Table 4 the quarterly
depositions are summed between 1972 and mid-year 1977 in Table 5,
where the specific deposition in mCi/km2 per mm of precipitation
is also tabulated. Comparing the specific deposition and the inte-
grated ground level air concentrations reveals no close correla-
tion. Instead it is evident that the mean concentration fields
differ at ground level .and at the altitudes of the precipitation
bearing clouds.
Kiruna Lyckiala Oitariund Stockholm CrindijBn Cothanburf. Ljun«byh»J
137Ca dapolition 1.301972(1)-1977(2)in mCi/kn2
:37C« dtpolition 1041972(1)-1»77(2)in t of tht avtrauvtlut 1.25 aCi/ka'
1J7Ca ipacific dapoiition S.I-10"1*
0.88
70
1.00
80
1.20 l.3«
108
1.79
142
3.9-10"- 5.1-10-*
in nCi/W par ampracipitation
n 7Ci ipacific dtpoiition 123 701972(l)-1977(2)in X of tha avaraga valua4.1.10"1 aCi/ka3-n>
83 109 93 122
Table 5. 137Cs deposition and deposition related to the amount ofprecipitation 1972 - mid-year 1977.
COMPARISON OF THE 95Zr/137Cs ACTIVITY RATIO IN GROUND LEVEL AIR
AND IN PRECIPITATION
It is well demonstrated by the ratio of tTie 95Zr/137Cs quotient
in ground level air to the corresponding value in precipitation,
that the compositions of radionuclides in these two types of
samples do not always agree. This fact has been pointed out
earlier, when the regular increase in this ratio during spring
was interpreted as being due to the enhanced downward transport
of old debris, especially old 137Cs, into the troposphere from
above (Bernström 1978).
30
In Fig 8 the (95Zr/137Cs)air/(95Zr/137Cs)prec ratio is plotted
from October 1976 to mid-summer 1977 for all stations sampling
both ground level air and precipitation.
0"T ' DEC I JAN ' FEB ' MAR ' APR1976 1977
Fig 8. The 95Zr/137Cs activity ratio inground level air divided by the same ra-tio in precipitation ([95Zr/!37Cs]air/["Zr/^'Csjprec) a* several Swedishsampling stations after the Chinese Sep-tember 26 1976 explosion and up to mid-year 1977.
31
The ratios seem to display a regular pattern composed of three
maxima interfoliated by minima of varying depths. When the debris
compartment enhanced in refractive masschains (large particles,
high 95Zr/137Cs-ratio) from the Chinese September 26 1976 explo-
sion first occurs at the altitudes of the precipitation bearing
clouds a minimum results which subsequently changes to a maximum
when the same debris compartment reaches ground level as an
effect of the gravitational settling. After a rather rapid de-
position of the larger particle debris the ratio can be expected
to become close to unity or even below that value as the debris
compartment enhanced in volatile mass chains (small particles,
low 95Zr/137Cs-ratio) at that time is expected to concentrate
at lower altitudes. Some fresh debris at relatively high alti-
tudes from the November 17 1976 event could then also have helped
to supress the ratio. The second and third maxima are most pro-
bably due to the spring peak phenomenon. The fact that the ratio
does not behave identically at all locations (especially at
Gothenburg the variations are much less pronounced) may be a
reasonably probable effect of different histories of the air
masses at the different locations but also of local variations
in especially the precipitation intensity.
32
WEEKLY SAMPLES OF GROUND LF7EL AIR AT KIRUNA, GRINDSJÖN AND
LJUNGBYHED
The results of the weekly samples of ground level air at Kiruna,
Grindsjön and Ljungbyhed are given for the period July 1975
to June 1977 in Appendix III.
To illustrate the results, the activity concentrations of 7Be,
95Zr, 137Cs and 1U0Ba at Grindsjön are plotted in Fig 9 for
the period July 1975 - June 1977. The cosmic ray produced 7Be
activity displays a spring maximum behavior in 1975, 1976 and
1977. The phenomenon is, however, more pronounced in the * "Cs-
curve which for 1975 and 1977 is partly due to the large injec-
tions of fresh debris during preceding years. Another reason is
of course that while 7Be is continuously produced in a wide alti-
tude band from ground level up to above 30 km (Lai et al 1968)
the debris from large scale nuclear tests is usually injected
into a more narrow band in the lower stratosphere. The debris
is thus bound to follow more closely the seasonal variation in
the downward transport rate from the stratosphere than are the
cosmic ray produced nuclei. The 95Zr (Tj . = 65 days) and llt0Ba
(Tj . = 12.8 days) activities display the occurrence of semi
short-lived and short-lived debris which more closely depict
the individual nuclear tests.
Fig 10 summarizes the 7Be, 95Zr, 137Cs and ll4°Ba concentrations
at Grindsjön since August 1972.
To enhance interesting features in the variation with time of the
radionuclides, the activities at Grindsjön are plotted as quoti-
ents of the 95Zr activity in Appendix IV, Figs 1-16. The nuclide
95Zr is used as a suitable reference to reduce the local concen-
tration variations due to meteorological conditions. Furthermore
95Zr is often used as the standard nuclide in fractionation stu-
dies where the measured activity ratio is related to the one
formed in the fission process (Edvarson et al 1959). In App.IV,
10
10
] ^ ^ ^ ^ p - u - j ^ j v ^ ^
Fig 9. 7Be, 95Zr, 137Cs and 11+0Ba ground level air concentrations (fCi/kg) at Grindsjön mid-year1975 to mid-year 1977. Vertical lines denote atmospheric nuclear tests in the northern hemisphere,
r * > u t l J w \ r r f ^Ul
Fig 10. 7Be, 95Zr, 137Cs and lw0Ba ground level air concentrations (fCi/kg) at Grindsjön August1972 to mid-year 1977. Vertical lines denote atmospheric nuclear tests in the northern hemisphere,
35
Figs 17 and 18, the two fission product ratios 103Ru/106Ru and
l^Ce/^^Ce are plotted for the Grindsjön station. These ratios
are interesting since they consist of activities of identical chemi-
cal elements, which implies a high sensitivity to processes
ocurring before the mass chain yields have decayed to the ele-
ment in question. Also implied is a high sensitivity in following
the mixing of different debris compartments. To facilitate the
interpretation of the figures the dates of the Chinese nuclear
explosions are marked and the theoretical decay or build-up
lines of the fission product ratios are drawn. The starting
points of the lines are based on yield values given by Harley
et al. mainly for thermonuclear explosions in the Mt-range (Harley
et al. 1965). This is done as a standard which should be considered
when discussing pure fission explosions with a more low energetic
neutron spectrum. The 155Eu yield, which is not given by Harley
et al., is taken from the compilation by Meek et al. for high ener-
gy neutrons incident on 238U (Meek et al. 1972).
Erratum: Until a few years ago the half-life of 155Eu in most com-
pilations was reported as 1.81 years. Apparently this must have
been a misinterpretation of the measured one of 1810 days. Because
of this error the build-up lines drawn for the 155Eu/95Zr activity
ratio in Arntsing et al. 1976 was a factor of 2.74 displaced, which
in turn led the authors to a false conclusion.
36
HIGH ALTITUDE SAMPLES
Between July 1975 and June 1977 there was a total of 62 flight
missions to sample high altitude air. Many of these were per-
formed to collect fresh debris from the Chinese explosions, which
implies a concentration of flights to February and October-Decem-
ber of 1976. The radionuclide concentrations deduced frommost
samples taken are given in Appendix V together with the flight
dates, the altitudes and information on whether the altitude was
under or above the tropopause.
Before the Chinese explosion of September 26 1976 the concentra-
tion of bomb debris in the lower stratosphere was around twice
the upper troposphere values. This Chinese explosion delivered
a large part of its activities to the troposphere and lowered
the ratio to around 0.5 for less than a month. In the spring of
1977 the ratio rose two orders of magnitude due to the thermo-
nuclear test preceding November when most of the debris was in-
jected into the stratosphere.
There is evidence of maxima in both the 7Be and bomb debris con-
centrations in the lower stratosphere during March and April
1976, about one month before the spring maximum occurred at
ground level. In 1977 the spring peak phenomenon is more clearly
demonstrated by the double series of tropospheric and strato-
spheric samples taken between February 9 and June 6. In mid-March
the lower stratosphere concentrations increased threefold with
no accompanying increase in the upper troposphere. No break-
through appeared until late April and the upper troposphere
concentrations raised 10-15 times. This was only around 10 days
before a rapid increase occurred at ground level (Fig 9).
37
THE CHINESE LOW-YIELD EXPLOSION OF JANUARY 23 1976
On January 24 1976 the Hsinhua news agency announced that China
had performed a nuclear explosions test the day before. This was
the 18th of all known Chinese nuclear tests. No information was
given on weapon yield, where it was performed or whether it was
an atmospheric or an underground test. For some days the inter-
national press gave contradictory reports on the matter, espe-
cially concerning the atmospheric/underground issue. The U S
atomic energy detection system then reported that a low-yield
test had been carried out in the atmosphere at the Lop Nor test
site (40°N 90°E) at 2pm local time (0600 GMT) on January 23
(USERDA 1976).
It was estimated that the debris would reach Sweden around February 5.
On February 4, 5 and 6 exploratory searches were performed at high
altitudes, but with no positive results (Appendix V ) . Fresh
fission products were first detected at all ground level sta-
tions south of and including Hagfors, in filters used February 6-
9. Dating by the 95Nb/95Zr ratio revealed an age of the fission
products in good agreement with the date for the Chinese explo-
sion which then virtually excluded all other known possible sources
(mainly a Soviet underground explosion in the Semipalatinsk area
on January 15). In the following week, February 9-16, fresh acti-
vities were present at all ground level stations, even if the
concentrations were still lower at high latitudes (north of Hag-
fors). For four samples from the first three weeks the fractiona-
tion factors f._q, of some short-lived fission products were
established and the neutron reaction ratios (n,Y)/(n,2n) and
(n,Y)/(n,f) were calculated. The results are given in Table 6.
S«pli Mt.7
(n.Y) (n.y)(nTJnT TnTTT
r«b 02- Ljungbyhtd 1.5*0.3 3.0*0.2 4.6*0.3 3.4*0.3 6.9*0.5 6.6*0.5 • >20 1.4*0.1.
fib 02- Crind«j8n 3.6*0.7 2.7*0.1 4.3*0.2 3.0*0.2 S.StO.2 6-0*0,3 0.41*0.03 >38 1.4*0.3
T*b 09- CtindtjBn • 1.1*0.1 2.9*0.2 1.5*0.3 4.6*0.3 4,1*0.2 0.57*0.05 •
r«b 16- CrlndiJBn 330*39 1.4*0.2 6.7*1.3 - 4.5*0.5 3.(*0.4 - >420 260*60
Table 6. Fractionation factors (fA-95) and neutron reaction ratiosin some ground level samples taken after the January 23 1976 Chinese nu-clear explosion.
38
In this report fA_Qt- is defined as the observed mass A/mass 95
atom ratio at formation divided by the corresponding Mt-weapon
ratio according to Harley et al (Harley et al.1965). The error
introduced by using Mt-weapon fission yields instead of fission
yields for much slower neutrons should stay within 30% for all
nuclides considered except 103Ru for which the error might be a
factor of two (Meek et al. 1972). However, these errors have lit-
tle effect on the qualitative conclusions drawn.
The samples clearly display an opposite fractionation pattern,
i.e. nuclides with volatile oxides which are normally depleted
in "hot particles" are here enhanced. These findings are in
agreement with the negative results of the search for hot parti-
cles with autoradiographic methods. From the sensitive X-ray
films (no-screen type) it could be concluded that no hot particles
with activities higher than 0.02 pCi were present in the material
available. The anomalous values of the fractionation factor for
99Mo and the neutron reaction ratios for the week starting Febru-
ary 16, were the first pieces of evidence that 9gMo and 2 3 % p of
some unknown origin occurred in Sweden during 1976. These find-
ings are described in detail below in the Anomalous Activities
chapter.
The (n,y)/(n,2n) ratio, i.e. the number of 238U(n,y)239U related to
the 238U(n,2n)237U reactions in the explosion, is sensitive to the
energy spectrum of the neutrons and hence to the nature of the
weapon. Thermonuclear explosions usually display (n,y)/(n,2n)
ratios around unity while pure fission devices normally yield
ratios at least one order of magnitude higher. The lack of 237U
in the debris from the January 23 event establishes a lower
limit of 30 which indicates the test to have been of the second
category.
Another ratio that is sensitive to the nature of the devices is the num-
ber of 238U(n,y)23gU reactions in relation to the number of fissions.
39
Taking 95Zr as the fission indicator yields a (n,y)/(n,f)-ratio
of 1.4 + 0.3 for the January 23 explosion. As discussed below for
the September 26 1976 explosion, the relative fractionation of
uranium and zirconium is difficult to estimate and this should
be oorne in mind when interpreting the (n,y)/(n,f) ratio. This
problem does, however, not apply to the (n,y)/(n,2n) ratio as
these two reactions are both represented by uranium during the
particle formation.
The missing hot particles, the opposite fractionation and the
virtual absence of debris at high altitudes can be taken as
evidence that the low-yield January 23 explosion was carried out
close to the ground. A somewhat similar case which has been dis-
cussed is the low-yield test performed in China on November 18
1971 (De Geer et al. 1977). A major difference though is that the
1971 debris showed a very low (n,y)/(n,2n) ratio, whereas the
early 1976 material did not.
40
THE CHINESE MEDIUM RANGE YIELD EXPLOSION OF SEPTEMBER 26 1976
On the evening of September 26 1976 China announced that it had
successfully conducted a nuclear explosion test. According to
t.he weekly information issued by USERDA (USERDA 1976) the test
was performed at Lop Nor at 2 pm local time (0600 GMT) on Sep-
tember 26 with a yield in the range of 20-200 kt. The test caused
quite an intense interest as it resulted in an unusually high
deposition of short-lived radionuclides along the US eastern
seabord. Also in Sweden unusually high deposition values were
registered, especially in the southern parts (Appendix I). Not
since the large Soviet test series in 1962 had the monthly
average deposition of short-lived nuclides reached levels above
1 mCi/km2.
The first rather weak samples of fresh debris were collected on
the 4th of October at an altitude of 14 km (Appendix V ). In
view of what was later learned about the unusually high deposi-
tion in early October, it is evident that flights some kilometers
below the tropopause would probably have yielded much stronger samples.
At ground level the September 26 debris first occurred between
October 4 and 6 (as judged by the Stockholm sampler) and was then
the major contributor to the concentration fields of radionuclides
until the end of the year.
BULK SAMPLES
Fractionation factors (f.qr) in some high altitude samples and
in the ground level samples from Grindsjön up to December 6 1976
have been calculated and are given in Table 7. The ground level
samples for the first few weeks showed a high degree of so called
normal fractionation (f <1 for mass chains with volatile oxides)
which then gradually diminished and turned to a growing opposite
fractionation (f>1 for mass chains with volatile oxides).
41
Sample
Oct
Nov
Oct
Nov
040506122102
04-11-18-25-0 1 -08 -15-29-
14 km14141113.612
GrindsjönM
II
"
f
1111-
00------
99
.35*0.18
.24*0.12
.44*0.15
.46*0.34
.73*0.01
.95*0.02
£ 1 0 3
1.14*0.150.90*0.080.32*0.090.78*0.170.44*0.063.6 ±0.4
0.092*0.0010.225*0.0050.199*0.0030.310*0.0040.91 *0.011.03 *0.021.31 t0.032.03 »0.15
1.70*0.221.20*0.110.82*0.091.40*0.301.48*0.173.6 *0.5
0.49*0.011.01*0.020.60*0.010.81*0.011.09*0.021.19*0.031.26*0.032.34*0.18
*132
1.34*0.191.10*0.120.71*0.091.09*0.36
-
0.29*0.070.58*0.030.59*0.07-----
f 1U0
1.12*0.151.04*0.110.72*0.080.78*0.140.69*0.103.0 *0.4
0.38*0.010.50*0.050.76*0.020.84*0.021.32*0.031.50*0.141.51*0.142.49*0.28
J I M
1.39*0.181.16*0.111.09*0.111.23*0.261.21*0.133.3 *0.4
0.62*0.010.29*0.010.71*0.01-0.68*0.01g.88*0.0?1.60*0.042.12*0.14
0.97*0.250.8-»0.160.76», .22-1.30*0.44-
0.66*0.060.73*0.060.70*0.060.77*0.060.71*0.060.80*0 080.71*0.090.97*0.19
Table 7. Fractionation factors (fA-95) in some high-altitude andground level samples taken after the September 26 1976 Chinesenuclear explosion.
Since mass chain 103 is one of the most volatile the fractiona-
tion factor for 103Ru, f1 0 3, can serve as a sensitive fractiona-
tion index. In Fig 11, where f103 is plotted until the end of
1976 for the Kiruna, Grindsjön and Ljungbyhed stations, it can be
seen how the fractionation index (fj 0 3) increases linearly by 0.3
units per week up to late December. This linear increase depicts
the growing fraction of rest particles in debris at ground level.
1103
3-
-
2-
-
1-
-
i
T
K
(1
Oct
/
y
T A /
7/Nov
K Ar rf
1
' Dec
G
\
Fig 11. Fractionation of 103Ru rela-tive to 95Zr in ground level air atKiruna(K), Grindsjön (G) and Ljungby-hed (T) after the September 26 Chinesenuclear implosion.
42
A corresponding study of the lower stratosphere debris reveals
some interesting features. In Fig 12 the 95Zr concentration,
corrected for decay to the day of the explosion and the frac-
tionation index as defined above, are plotted for a series of
samples taken at 14 km altitude. There it can be seen how the
front edge of the debris cloud reached Sweden on October 4,
8 days after the explosion, that a maximum in the concentration
occurred one day later and that the cloud had a tail behind,
that persisted for about a week. About 18 days after the first
maximum a second one occurred signifying the second circumnavi-
gation of the earth. From the widths of the peaks defined at half
maximum it can be estimated that the latitudal cloud transverse
at 14 km was roughly 5000 km on the first pass and 8000 km on the
second. The activity increase which was seen in early November and
which had disappeared before November 16 is interpreted as being
due to a third circumnavigation.
50
05-
Explosion
26 Sep 1 Oct 10Oct 20 Oct iNov
Fig 12. Decay corrected 95Zr concentra-tion (fCi/kg) and fractionation of 103Rurelative to 95Zr in lower stratospheredebris after the September 26 Chinesenuclear explosion.
43
The fractionation index in the lower part of Fig 12 indicates that
the cloud (or better the cloud intersect at 14 km) when passing
over Sweden for the first two times had a center region with a
larger concentration of hot particles than in the leading edge and
in the tar'l. It would appear that a hot particle cloud was embedded
in a larger rest particle cloud. The phenomenon should be under-
stood as a result of a hot particle cloud descending through a
rest particle cloud, with the former being less widely distri-
buted due to a different history in the diffusion and wind speed
fields of the lower stratosphere.
The relatively large displacement of the total activity maximum
and the fractionation index minimum on the first circumnaviga-
tion would then be due to the fact that the total activity maxi-
mum was highly dominated by the rest particle cloud. This effect
disappeared on the second passage as the rest particle cloud was
then more dispersed.
PARTICLE PROPERTIES
Autoradiographic examinations confirmed that a considerable part
of the early samples consisted of hot particles. Some hundred par-
ticles between 0.7 and 7.8 um were red or reddish, a feature en-
countered only once earlier in the series of Chinese nuclear
tests, namely the low-yield explosion of December 24 1967 (Sisefsky
et al 1970). The rest were mainly colourless or yellowish. As
usual most of the particles were spherical, sometimes ellipsoidal.
Particles revealing crystalline features were very rare. Several
had satellites or consisted of two coalesced particles of the
same size-order.
Samples of assorted particles of different size-classes were
examined by Y~spectroscopy in order to examine variations in
nuclide composition with size. The resulting nuclide concentra-
tions and fractionation factors are given in Tables 8 and 9 for
the smallest size-class, the largest size-class 1 single red
44
particle and 1 single colourless particle. As has often been found
before, the degree of fractionation for many mass chains increases
with the particle size within the hot particle range. If, as has
been observed in many cases (e.g. Mamuro et al. 1963), the main
constituent of th? red particles is Fe2O3 and of the light or co-
lourless particles A12O3,the high 95Zr-concentration of the colour-
less particles can be understood in terms of the higher boiling
point of A12O3 as compared to Fe2O3. The colourless particles have
started condensation earlier than the red ones and have thus been
more effective in incorporating refractive oxides. With relative
concentration gradients within the cooling cloud the initial con-
figuration of aluminum, steel and fissile material in the exploding
device could also possibly affect the particle formation.
He anVOIUM
86 Minly r«d ptr t ic l t» 0 .9 -1 .4m 1.07 25*2
21 n l n l y r..1 p t r t i c l t * 3.0-3.Zum 15.6 29*2
1 r«d partici.» 3.9uw4.9w» 39 41*2
1 colourl««f rtirciclc 2.bum 7.4 202*14
13) i-M ' . 3 1 >. 1
0.80*0.20 3.9*1.4 15i2
0.7210.18 3.1*0.5 13*2
3 .0 *0 .3 1.3 «0.2 4 .710 .4 3 .410 .7 3 . 8 *0 .6 12*1
2Qi4
22.)
21*i 7.6*1.
25.5 11 12
87*20
Table 8. Atoms per (ym)3-10 4 of some mass chains in different par-ticle fractions.
Snplt '10! I l l '.n I..- I . . .
It f*rt ic l«i 0.9 - ! . ' » •
21 pirtic:** 3.0 - ) 2.»
1 tti parcicl* 3.9uffl"'>,9um
1 iOlourl*** p l t t l c l* 2.4va
1.07 0.09:0.010 0.1 ;:C.0i aelsO.10 0,M:0.20
15.6 O.OW;0.006 Q.IOTO.02 0.51t0.06 1(16:0.1) 0..9:C.;2
19 0.6612.0» 0.011:0.307 0.20:0.0) 0.10::.01 0.0910.01 0.11:0.01 [165-0.!» ..<.».:;,"«
7.4 0.11:0.02 'J.46.'0.11
Table 9. Fractionation factors, f^'95'ferent particle fractions.
s o m e n>ass chains in dif-
By help of autoradiographic methods the 3-activity of the particles
was measured individually and was found to be at larp.e propor-
tional to its volume, which is typical for an explosion of low to
medium range yield without contact with the ground. The specific
45
3-activities normalised to a debris age of 100 days were deter-
mined for a total of 282 particles,which were subsequently di-
vided into different classes according to size and colour. The
distributions thus obtained were plotted in a log-normal diagram
and the geometric means (medians) and standard deviations were
determined for the best fit of a log-normal distribution. The
procedure is illustrated in Fig 13 for the distribution of all
particles measured (282), for all clearly red particles (237)
and for all light or colourless particles (22).
99,99%
0,01*2 3 4 5 6 789! 12
103 4 5 6 7 8 9 ' 12
102 3 4 5 6 7 8 9 1 1 2
Fig 13. Cumulative distribution of the specific activities (at theage of 100 days) for, from left to right, all 282 particles mea-sured, 237 clearly red particles and 22 clearly light or colour-less particles from the September 26 1976 Chinese nuclear explo-sion (log-normal diagrams).
Even if the effect is small, it is evident that the light-coloured
particle fraction yields a higher median specific activity than the
red one. In Table 10 the resulting geometric means and standard de-
viations are given for all the classes tested. There it is estab-
lished that the size also affects the specific activity. Both these
46
findings complete the picture of the fractionation effects de-
scribed above as they mainly depict the increased incorporation
(as shown in Table 8) of mass chain 95 and to a lesser extent the
chains 141 and 144 in particles of larger size and lighter colour.
The 3~activity of mixed fission products at an age of 100 days is
dominated by the mass chains 95, 91, 89, 141, 144 and 103 out of
which 91, 89 and 103 are very volatile and thus of reduced signi-
ficane for the hot particle total B~activity.
Number ofparticles Colour
Specific activity dpmB( 100.1)/(inn) 3
Diameters — — — — — • — •
(inn) Ceometric mean Geometric stand.dev.
282
237
72
64
53
40
22
Observedmixture
red
red
red
red
redlight orcolourless
0.7-4.8
0.7-4.8
0.7-l.f)
1.6-2.2
2.2-2.8
2.8-4.8
0.8-3.0
3.4
3.5
2 .9
3.0
3.5
3.7
3.8
1.6
1.5
1.5
1.5
1.5
1.6
1.9
Table 10. Median specific activities of differentparticle classes.
NEUTRON REACTION PRODUCTS
Apart from the fission products a few radionuclides originating
from reactions of neutrons with construction materials have been
detected. The concentrations are given in form of nuclide ratios
in Table 11 where also the reaction significant for the produc-
tion is indicated.
Both 239Np and 2 3 7U were only detected in some of the first heavi-
ly fractionated ground level samples. As uranium could very well
be orders of magnitude more abundant than the fission products in
the fireball, the normal concept of fractionation between differ-
ent trace elements should not be applied for the uranium isotopes.
The large variation of a factor of 5.5 in the mass 239/mass 95
ratio indicates a fractionation behaviour of the uranium that
47
IsotopeNuclide ratio toat formation
Significant activationreaction
n9Np 0 . 8 6 1 - 4 . 7 8
2 3 7 U 0 . 0 2 8 - O . l f . 051*Mn 0.022 ± 0.00157Co 0.0083 t 0.0008
58Co 0.0396 i 0.0021
M'Fe(n,p)5''Mn
'>HNi(n,p)r'RCo
Rea«:t ion ratios
(n.Y)/(n,2n) - 31 i 3
(n,Y)/(n,f) - 0.052-0.29
58Co/5uHn - 1.82 ±0.10
58Co/57Co - 4.8 10.5
Table 11. Comparison of different neutron reac-tions in the September 26 1976 nuclear explosion.
differs from that of the fission products. Uranium oxide present
in trace amounts should, according to its high temperature proper-
ties, fractionate like the semi-volatile fission product mass-
chains. However the maximum variation of f , for the fission
products in the samples corresponding to the extreme mass 239/
mass 95 ratio (the first two fresh debris samples from Gindsjön)
is only 2.5 (Table 7), which is less than half the mass 239/
mass 95 variation.
The (n,y)/(n,2n) ratio of 31 ±3, which is not affected by the
fractionation problem is typical of a fission device without any
significant thermonuclear contributions.
The ratios involving manganese and cobalt isotopes are based on
samples taken at Grindsjön in October, November and December 1976.
The errors are the standard deviations of 6-14 determinations in
differently fractionated samples. The rather small deviations in-
dicate what could be expected, namely that there is no significant
fractionation between the Mn, Co and Zr tracers. The 58Co and 5I*Mn
activities are due to result from (n.p)-reactions in steel. The
ratio of the cross-sections for these reactions does not vary much
48
for neutron energies below 8 MeV and can thus be represented by
the fission neutron average cross section ratio o[58Ni(n,p)] =
113 mb/o[5ltFe(n,p)] = 82.5 mb (IAEA 197A). The 58Co/54Mn atom
ratio of 1.82 then yields a Ni/Fe ratio of 0.12 which is consist-
ent with common concentrations of nickel used in stainless steel.
There is no way in which the amounts of 57Co detected can be produce-
ed in a pure fission explosion by activation of any stable isotope,
The 57Co activity could have been added to the device, as a tra-
cer for diagnostic reasons. In such a case the 57Co/95Zr-ratio
indicates that around 60 Ci of 57Co has been added per kt fission
corresponding to a total amount of as much as 1-10 kCi. Another,
more probable, explanation is that the experiment actually in-
volved thermonuclear reactions, which did not affect much of the
2 3 8U, but did induce 57Co through the 58Ni(n,d)57Co reaction in
some parts of the steel. This conclusion is supported by an indi-
cation just below the detection limit of 24Na (Tj . =15h) in one
of the earliest measurements. The 24Na is produced in (n,a) reac-
tions in aluminum which are only important for neutron energies
above 6 MeV (BNL-325).
49
THE CHINESE HIGH YIELD EXPLOSION OF NOVEMBER 17 1976
At 2 pm local time on November 17 1976, China conducted her twen-
ty-first nuclear test explosion. (The twentieth test was per-
formed underground on October 17 1976, giving rise to no radio-
activity in air in Sweden.) The US atomic energy detection sys-
tem announced that the yield of the test was around 4 Mt which
means that it was the largest Chinese test up to that date
(USERDA 1976). Later a total yield of 4.2 Mt with a fission
contribution of 50±15% has been reported from American labora-
tories (Thomas 1977, Leifer et al. 1978a). The main part of the
debris cloud rose to an altitude of around 20 km above the
Lop Nor test area (Leifer et al. 1978a).
The first sample of fresh debris in Sweden was collected in the
lower stratosphere on November 25, 8 days after the explosion
(Appendix V ) . The following day a stratospheric flight yielded an
unusually strong sample (corresponding to 1.6*1011 fissions).
By November 30 the cloud had essentially passed. Two weeks later
it was detected on its second circumnavigation around the globe.
From mid-December until early February 1977 no sampling flights
were conducted. Then a series of paired upper troposphere and
lower stratosphere flights was started to trace the enhanced
downward transport of debris from the stratosphere usually
occurring during the spring (see "High altitude samples" above).
At ground level very little was detected xluring the first months
from the November 17 explosion. The only activities that could
then easily be associated with the November event was the abundant-
ly produced short-lived isotope 2 3 7U and mass chain 95 which ren-
ders the possibility of dating the sample age. Not until early March
and primarily early May, with the advent of the spring peak, did
the concentration levels due to the large thermonuclear explosion
increase considerably.
50
FRACTIONATION AND PARTICLE PROPERTIES
Several samples of the November 17 1976 debris were collected in
the upper troposphere and the lower stratosphere during 1976 and
1977. The radionuclide activity concentrations given in Appen-
dix V have been used to calculate fractionation factors, fA_Qr»
which are presented in Table 12. The errors stated for the frac-
tionation factors are the root-square-sum of the individual errors
given by the analysis program but with the systematic contribu-
tion connected with the determination of the absolute detector
efficiency subtracted.
The samples display only small signs of fractionation effects
between the fission products, and the 237U/95Zr-ratio does not
vary in any way that could indicate any significant fractiona-
tion between the fission products and a uranium matrix. In a few
samples the fractionation factors of some long-lived activities
are very high, which is due to mixing with older debris in the
stratospheric inventory. This is most evident in the gap between
the first two circumnavigations, i.e. in early December 1976,
before the cloud had dispersed enough to lose much of its meri-
dional variation. One sample in the gap, collected on December 8,
seems to be the only one disturbed by 95Zr from the preceding explo-
sion in September.
The apparent non-fractionation of the ground level samples is
well illustrated in the figures of Appendix IV, where the observed
activities relative to that of 95Zr clearly falls close to the
November 17 1976 theoretical lines, after the effect of the pre-
ceding explosion completely declined around February, March.
As could very well be expected from the fractionation properties
of the bulk samples, n- hot particles were found in the auto-
radiographic examinations. Only a haze of blackening resulted
from particles, too weak to be resolved as black spots on the
x-ray films. Similar cases have been met with earlier, e.g. the
Hu«hcr of fi-uioni
T tht . 4 ^ 1 . i t t .n . th t , , ( , „ t , , t l l ; s t , , , f , , ? 1 » , '.un ' , > , < i » ' , > , t | S S i»5*"
l.Ofc'0.19 1.03*0.20 1.21*0.21 0.95*0.20 0.84*0.20 1.00-0.17 0.84!0.16 0.89*0.20 3.*»('O.56
1.04*0.02 1.06*0.02 O.B7-U.O2 1.6**0.0» 1.26:0.02 0.86*11.02 1.06*0.02 0.86*0.01 1.(1210.02 0.92-1.03 0.81*0.04 1.05:0.07 1.80-0.11
1.11*0.04 1.06*0.02 0.94*0.05 1.21-0.02 0.90-0.05 2.02-0.31 0.90*0.02 1.03*0.02 0.92-0.04 0.83*0.06 3.89*0.29
1.07*0.2* 1.1910.JO 1.71:0.3* 1.04:0.27 201*45 0.97*0.21 1.15:0.25 10.9*1.2 1.4»:0.54 4.11:0.91
0.13:0.23 1.1S*O\I9 I..'8-0.22 117*25 0.61-0.12 0.9510.16 6.1*1.5 1.31:0.51 1.40-0.62
1.06:0.46 l.B5:O.8O 500*211 0.78*0.16 1.08*0.48 28-12 3.16!!.51
0.74*0.19 44*14 2K4-101 1.10-0.10 4n:*IOO 0.56*0.17 l . l l - ' ' .3O 17*5 2.29*0.68
1.14*0.05 1.08*0.02 0.85-0.10 1.34*0.02 0.86*0.06 1.81*0.15 0.90*0.02 1.04*0.02 0.99*0.04 0.84*0.06 6 .03:0. )0
1.05*0.02 0.82:0.02 1.64:0.10 1.14:0.04 1.16-0.02 0.90:0.03 0.A5-0.01 0.78-0.09 4.31:0.39
1.16*0.10 4.3*1.4 1.24:0.10 1 ?0!0.22
1,14*0.0? 0.96*0.10 2.25:0.55 1.56*0.29 2.24*0.13 O.*»?*O.O4 1.07*0.02 0 .91-0 .03
0.96*0.09 0.»6*0.0»
1.13-0.01 1.05:0.17 5.4*1-0.21 O.9O-0.Q7 1.08*0.02 0.98-O.O5
1.10*0.05 1.21-O.S4 1.16:0.14 1.01*0.05 0.91-0.14
1.11*0.02 1.25-0.11 1.6J-0.39 1.64*;l.l? 0.89*0.06 1.05:0.02 0.91-0.04
1.15:0.03 1.15'O.J» 7.:O*1.5O 4.10-0.29 0 .69:0.22 1.05-O.01 0.89-0.05
1.10-0.02 0.88:0.05 1.74*0.JO 1.17-0.05 1.04-0.06 1.11*0.02 0.96*0.01
1.14*0.03 0.98*0.19 4.46*1.15 2.27-0.24 0 . 7 1 - 0 . 1 ; l . i : - 0 . 0 1 O.**7-O.O5
1.09*0.02 0.92-0.01 1.80-O.K 1.11*0.01 0.8V0.0* l.u»*0.02 0.91-0.01
1.11*0.01 0.91*0.02 1.89!0.13 1.19'Q.O} 0.87*0.06 1.06*0.C2 0.88*0.03 2.00:0.39
' '.08*0.05 1.05:0.26 5.07*1.54 2.40-0.30 1.10:0.05 0.90:0.07
1.07:0.03 0.94*0.03 1.72*0.18 1.17:0.04 0.»6:0.IJ 1.12:0.01 0.95-0.01 0.12:0.25
1.12:0.03 0.91*0.06 2.74-0.35 1.29-0.06 1.10*0.02 0.91:0,03
1.07*0.03 0.96*0.04 1.61*0.20 1.12-0.04 1.00:0.20 1.11*0.02 0.96*0.01 l.lltO-35
1.13:0.05 1.01*0.1» 3.74*0.85 2.19*0.19 1.18*0.04 0.86*0.05
1.07*0.01 0.91*0.03 1.45*0.17 1.22*0.04 1.14:0.02 0.96*0.03 1.08:0.27
1.04*0.06 O.B7-O.O8 1.91-0.37 1.42-1).08 1.06*0.01 0.92-0.04
1.07*0.04 0.94*0.01 1.56*0.17 1.17-0.04 1.11*0.02 0.94:0.01 1.03*0.25
1.09*0.04 0.90*0.01 1.7B*O.O8 1.18*0.03 1.06:0.02 0.91:0.01 0.99:0.17
Table 12. Fractionation factors in samples collected in the upper troposphere and lower stra-tosphere of debris from the Chinese November 17 1976 thermonuclear explosion.
7*1125
1126
1129
1130
1202
1203
120*
120»
1214
770203
02O9|
02141
O222J
0303/
031M
0322
0 4 i a |
042 7<
0 5 1 l |
06a* |
0*14
S
sssssss5
5
T
sT
sT
S
T
S
T
S
S
T
sT
S
T
S
T
S
s
9.4.10'
l . i -W*
9.3-10'
4.5-10'
2.0-10'
3.510'
2.3-10'
3.3-10'
9.6-10'
».SIO10
3.6-10»
S.»-10'
3.0-10*
1.510'
5.5-10'
6.4-10'
9.2*10*
1.4-10"
1.2-10'
4.1-10"
6.810"
1.4-10'
5.3-10"
1.3-10"
5.0-10"
2.3-10"
4.4-10"
t.9-1'11
4.4-10"
». I - IO"
52
Chinese thermonuclear tests of December 27 1968, September 29
1969, October 14 1970 and June 27 1973, but then at least a few
microscopical particles were found with high specific activities
of the order of 300 dpm£!/(um)3 at 100 days.
THE STRATOSPHERIC SAMPLE COLLECTED ON NOVEMBER 26 1976
The exploratory flight performed on November 26 1976 at an alti-
tude of 14 km yielded the strongest sample of nuclear debris
collected by this laboratory since the early 1960:s. This sample
was repeatedly studied by y~spectroscopy for more than a year.
Besides the 13 fission products and the 4 neutron activation pro-
ducts listed in Appendix V another 12 fission products and 4
neutron activation products were detected. Table 13 gives the
absolute number of parent -itoms at formation for all nuclides
detected in the sample, and the ratio of ^arent atoms to the
number of fission events normalised to a mass 95 chain yield of
5.07% (Harley et al. 1965).
Appendix VI illustrates the Ge(Li)-spectra recorded 13.1, 50.2,
174 and 356 days after the explosion. The y~peaks are here
marked with the true 6~decay precursor irrespective of half-life,
while most of the mass chains in text and tables are represented
by the nuclide with the half-life of interest. Secondary activi-
ties with no independent yields in any possible fission mode,
like 140La and 1 3 2 I , bear no information on the test and are con-
sequently not discussed, or reported in the tables. The X-rays
are marked with the nuclide from which it is emitted, e.g. Np-X
for the 237U-decay. All nuclides detected are labelled in Appen-
dix VI except 105Rh and 11JAg, 105Rh because its main y-ray
(319.2 keV) almost coincides with a 147Nd y-ray (319.7 keV) and
***Ag because a summation of several of the earliest spectra
was needed for detection. For some nuclides with strong y-casca-
des the summation peaks are labelled in Appendix VI with a
Z when a correspcnding crossover y~transition does not exist or
is of no significance as'compared to the summation effect. These
ri.U ol• Inte****"» T'«l* «' •»»•""«" >«>.'-
Table 13. Results of the ganma-spectrometric analysis of the November 26high-altitude sample and a comparison of the deduced chain yields with chainyields published for Mt-weapon neutron-, 14 MeV neutron- and fission neutron-induced fission of 238U.
54
coincidence summation problems mainly occurred for loeRh, 1 3 2 I ,
140Ba, 239Np and 2 3 7U (with X-rays).
Mass chain yields
As the samples of the November 17 1976 debris showed a low degree
of fractionation, the number of parent atoms per fission for most
nuclides given in Table 13 depicts the cumulative yield of these
nuclides in fission of the fissile material present (mainly 2 3 8U)
and in the neutron environment of that specific explosion. The
chain yields thus derived are compared to the Mt-weapon yields
as given by Harley et al (Harley et al. 1965) and the yields for
14 MeV and fission spectrum neutrons incident on 238U as com-
piled by Crouch (Crouch 1977). For those fission products obser-
ved which do not represent the full chain yield, due to a long-
lived precursor (126Sb), a stable precursor (136Cs) or the in-
fluence of an isomer (115Cd, 1Z5Sn, 1 2 9 mTe), the chain yields
have been estimated by applying a conversion factor based on
data compiled by Meek et al (Meek et al 1972). This conversion
factor can vary considerably with fission mode and in Table 13
the results of the conversion are given both for 14 MeV neutrons
and for fission spectrum neutrons incident on 2 3 8U.
The comparison of the observed mass yield values with the two
238U mass yield curves, which can be said to represent fission
ind..*_ed by extreme D-T fusion and extreme fission neutrons, is
illustrated in Fig 14. The fully experimental points are here
denoted by open circles with error bars and the values derived
from partial yields are represented by the intervals indicated
in Table 13. Mass 115 is marked with a circle as the effect of
the conversion is smaller than the original error bars.
All chain yields fall between the two extremes, apart from mass
132 which seems to be around 20% low and mass 133 which is low
by as much as a factor of 50. Although within the extremes,
masses 140, 141 and 143 seem to be around ten percent low, which
55
0,001
0,01
70 120 130 140 150 160
Fig 14. Percentage cumulative mass-yields (normalised to Y(A=95)== 5.07 %) as determined from the November 26 1976 sample. The pointsdenoted by circles with error bars are fully experimental whilemass-yields only indicated by a range (A=126, 129, 136) need fur-ther information on the energy of the incident neutron to fix theposition. For mass 133 its indicator 133Xe diffuses out of theparticles and the range given corresponds to analysises at dif-ferent ages of the samples.
For comparison the mass-yield curves for fission neutron inducedfission of 2 3 8U (a) and for 14 MeV neutron induced fission of2 3 8U (b) are given (Crouch 1977). The inset scale gives the yieldfor symmetric fission of 2 3 8U as a function of the energy of theincident neutron (Nagy et al. 1978).
56
should be due to the fact that these decay chains involve noble
gas-isotopes (xenon) at early time. For mass 132 the reason could
be that there is some independent yield at a higher charge than
tellurium, which is the tabulated mass 132 nuclide. That this is
the case is indicated by several experimental results relerred
to in the above compilations for the 14 MeV, 2 3 8U case.
133Xe diffusion
The large chain yield deviation for mass 133, built into the
particles as antimony, tellurium and iodine, is due to the fact
that the chain after some days is present in the form of xenon.
Being a noble gas xenon is expected to diffuse out of the parti-
cles. During the first twenty measurements (between November 27
and December 29 1976) the 133Xe abundance was determined by a
very careful correction for the lut*Ce and 131I contributions in
the complex 80 keV y-peak. Errors having large effects on this
correction, such as those in the relative detector efficiencies
and in the reported y~ray branchings, were minimized by employing
a m C e (80.1 keV)/lltt+Ce(133.5 keV) ratio measured well after the
decay of 133Xe and a 131I (80.2 keV)/131I (364,5 keV) ratio deter-
mined from a special study of 131I in an identical counting geo-
metry. In this way an apparent half-life of 4.8±0.2 days could
be deduced for 133Xe, which, when compared to the physical half-
life of 5.29 days, indicates a diffusion process going on with
a characteristic half-life of 2±1 months during the period of
measurements. This diffusion rate provides no explanation at all
for the missing 98 %, so a diffusion process of a much higher
rate must have occurred directly after the formation of the xenon.
This can be interpreted such that the fast diffusion occurs from
the surface region of the particles, and the slow component arises
from diffusion from the interior of the particles. A high fast/
slow diffusion ratio as in the present sample would then imply a
high surface/volume ratio, i.e. very small size particles, which
is consistent with the observations above. In a sample from the
Chinese low-yield explosion of November 18 1971, where the en-
57
hanced volatile mass-chains indicated submicron particles, a
slow component diffusion of xenon was observed which could account
for all the missing xenon (De Geer et al. 1977). These submicron
particles were thus considerably larger than the ones from the
November 17 1976 explosion, in agreement with what would be ex-
pected from the difference in explosion yields.
95Nb/95Zr-dating
The 95Nb/95Zr activity ratio gives a good means for dating nu-
clear debris of ages up to around a year. The long series of
measurements of the November 26 sample was used to construct a
plot (Fig 15) that gives the ratio of the 95Nb 765.8 keV peak
area as a function of age. This plot facilitates future datings
and eliminates errors due to uncertainties in half-lives and
branching factors otherwise used for the calculation.
Symmetric fission probability
The probability of symmetric fission increases with increasing
energy of the incident neutron. For 2 3 8U the symmetric fission
probability as a function of the neutron energy in the region
of interest has recently been published (Nagy et al 1978). In
Fig 14 this function is indicated on an inset scale giving the
depth of the valley for different neutron energies. According
to this scale, the average neutron energy causing fission of
2 3 8U in the November 17 1976 explosion lies close to 10 MeV. This
can be accomplished by a time-integrated neutron spectrum essen-
tially concentrated around 10 MeV or, for example by a linear spectrum
above the fission threshold (which as is easily shown, has to be
rectangular to give the symmetric fission probability actually
observed) with about 60 % of the neutrons above 7MeV (the threshold
for the 238U(n,2n)237U reactions which are further discussed be-
low). Another spectrum which is probably more realistic is one
with one peak at high energy (14 MeV) and another one at low
energy (at a few MeV): In this case the experimental symmetric
fission probability fits if more than 30 % of the fissions induced
in 2 3 8U are due to the high energy neutrons. Note that these
58
Peak area Nb 95 (765 keV)
Peak area Zr 95 (756keV)
500 days
30 40 50 days
Fig 15. Count rate ratio of the 95Nb 765.8 keV y-line to the 95Zr756.7 keV y l i n e as a function of debris age. The plot i s deter-mined from several measurements of the November 26 1976 sample ona detector with an efficiency ra t io of 0.9884 between the two ener-gies .
59
spectra are not necessarily typical for any part of the explosion,
but rather comprise spectra synthezised by neutrons at all dif-
ferent regions where fission occurs.
Low Z activation products
Of the low Z activation products 58Co is the most abundant. Nor-
malised to 58Co the other products follow with 39 % for 54Mn,
27% for 8 8Y, 5.3% for 60Co, 5 % for 65Zn and 2.4% for 57Co (de-
duced from Table 13). The relative amounts of the cobalt and the
manganese isotopes agree with what is expected from an exposure
of steel (with a concentration of around 10-15 % of nickel) to a
neutron flux of thermonuclear origin. The principal production
reactions have then been assumed to be 5l*Fe(n,p)51*Mn, 58Ni(n,d)57Co,
58Ni(n,pn)57Co, 58Ni(n,p)58Co and 59Co(n,Y)60Co. The high 60Co/57Co
ratio excludes, according to the cross-section curves (e.g. in
Alley et al.1973), the 60Ni(n,p)60Co reaction as the main pro-
duction mode of 60Co. This implies that some cobalt must have
been present in the material for the n-capture reaction to occur.
In the same way the 57Co/58Co ratio bears information on the
energy spectrum of the time-integrated neutron flux through the
steel. To explain the ratio observed, some parts of the steel
must have been exposed to neutrons above 7 MeV. The 65Zn activity
most probably results from neuiron capture in zinc present in
contructional material alloys.
The 88Y activity is probably produced in-the 89Y(n,2n) reaction.
The cross-section of this reaction shows a sharp threshold at
12 MeV reaching 800 mb at 14 MeV incident neutron energy. This,
and the fact that 88Y is not produced in any other reaction
makes yttrium a suitable monitor of the high energy flux which
probably is used for diagnostics of the burning process.
High Z activation products
In Table 13 the 2 3 7U and 239Np nuclide concentrations, signifying
the neutron capture and the (n,2n) reactions on 2 3 8U are also
60
given. The (n,Y)/(n,2n) ratio of 1.34 + 0.04 implies a thermonu-
clear explosion. Due to the very low fractionation of the debris
the (n,Y)/(n,f) ratio of 0.26+0.03 and the (n,?.n)/(n,f ) ratio
of 0.20±0.02 can also be regarded as undisturbed. If, as is
indicated by the symmetric fission probability, at least 30 %
of the fission events occurring in 23^u w e r e induced by neutrons
of energies above 7 MeV, it follows from the reaction cross sec-
tions (BNL 325 1965, IAEA 1974) that there would be at least
40 237U nuclides produced for each 100 fissions. As the observed
(n,2n)/(n,f) ratio is 0.20, 20 or more 237U nuclides per 100
fissions must have been destroyed through subsequent (n,2n)-,
(nh.e.»f)~> (nb.th.»f)~ anc* (n,y)~reactions. Depending onwhether
the high energy neutron flux (h.e.) or the bomb-thermal flux (b.th.)
would be dominant in the regions where the 237U was formed, the
first two or the second two reactions respectively, would be the
most important. In the first case this implies a high-energy
neutron flux of the order of 1 mol/cm2»s.
Two of the filtering devices of the November 26 1976 flight were
loaded with Microsorbair^ filters. From these filters samples were
prepared for a-spectroscopy of plutonium, americium and curium
isotopes at the Department of Radiation Physics at the University
of Lund, Sweden (E. Holm 1978). From a measurement performed at a
debris age of 1.82 years it was concluded that (normalized to
7.98-109 mass-95 atoms as in Table 13) the debris contained 14 ± 7
fCi of 238Pu, 1190 + 80 fCi of 239+2l+0Pu, 64 ± 24 fCi of 2klkm and
less than 3 fCi of 2t+2Cm (not detected).
If it is assumed that plutonium was not part of the device, the
239Pu, 21+0Pu and 21tlAm must solely arise from the decay of multiple
neutron capture products of 2 3 8U. In that case Table 13 can be
supplemented by Table 14, in which the 239Np has been used to re-
solve the 239Pu and 240Pu isotopes. The resulting 240U/239U ini-
tial atom ratio of 0.050 ±0.028 is quite low compared to 0.363 in
debris from Mike, the first thermonuclear explosion in 1952 (Dia-
mond et al. 1960), and also compared to 0.135 which has been re-
61
Isotope
Number ofHalf-life partnt atoms(years) »10~?
Parent atoms Parent atomper fission ratio to the(7.) 239Pu-parent
2 38pu
2 3 9pu
2"°Pu
2" »Am
2-2Cra*
• Not
87
2.44
6540
433
0
detected
.8
•10"
.466
0.0020*0.0010
41.4 ±0.9
2.1 ±1.2
0.59 ±0.2.!
<0.00003
0.0013
26.3
1.3
0.37
<0.00002
(4.
1
0.
0.
<8-
9±2.4)
050±0.
014±0.
io-7
•10-*
028
005
Table 14. or-emi t ter s in the November 26 high-altitudesample. The values for 239Pu and 2t*°Pu are based onthe assumption that all 239Pu detected is due to the6-decay of 239Np.
ported for debris dominated by the June 17 1974 Chinese thermo-
nuclear explosion (Leifer et al. 1978b). The 21tlU/239U initial
atom ratio of 0.014 ±0.005 is also lower, but not so much, than
the corresponding Mike ratio of 0.039.
If it is not from (n,2n) reactions on device plutonium, the 238Pu
detected could be remnants of a neutron initiator or possibly re-
sult from (d,2n) and/or (n,p) reactions in 2 3 8U. The (d,2n) reac-
tion was discussed by Bell (Bell 1965) to explain the reversal of
the odd-even effect at high mass in the multiple neutron capture
process of uranium.
62
ANOMALOUS ACTIVITIES
On some occasions during the two years covered by this report air-
borne radionuclides that neither were of natural origin nor were
rest-products from any atmospheric nuclear explosion were detected
in southern Sweden. One, a few or all of 239Np, 99Mo, 131I an(j
ll|0Ba were observed at several stations on five occasions during
the first half of 1976 (De Geer 1977) and traces of 75Se, 12 3mTe
and 131I were detected at single stations during some single weeks.
It should be noted that most of the observations were made between
the falls of 1975 and 1976 when the "background" activities from
preceding nuclear tests in the atmosphere were the lowest since
regular measurements of airborne radioactivity started in Sweden
in the mid-fifties. The anomalous activities found are summarized
in Fig 16.
"Mo, If B a
On five occasions during the first half of 1976, in late February,
March, April, May and July, unusual mixtures of short-lived radio-
nuclides were detected at several sampling stations in southern
Sweden. Most of the activity was due to the two nuclides 239Np
and 99Mo (half-lives, 2.35 and 2.75 days, respectively), but some
131I and 140Ba (half-lives, 8.05 and 12.8 days, respectively) were
also observed. Fig 17 gives a pertinent spectrum detail of a sample
taken at Grindsjön in April.
The Chinese low-yield test of January 23 1976 could easily account
for the 1 3 1I- and ^"Ba-activities ir. February and March, hut could
not explain the presence of the very short-lived 239Np and 99Mo
activities from late February on or the 131I and 140Ba from April
on. The short-lived nuclides (half-life i 12.8 days) that appeared
in Sweden after the Chinese test and on the five subsequent occa-
sions are collected in Table 15 for the Grindsjön and Ljungbyhed
sampling stations. The values given include the statistical, de-
tector efficiency and y/fJ-branching errors. In the measurements
63
pCi-s/kg
1000
100
10
239, Np
| GRINOSJÖNg STOCKHOLMö LJUNGBYHED
100
10
1000
100
10
•
r y
III1 1 1 1 1 1 1 1 1
l l1 1
11 '
140Ba
1 f 1
1000
100
10
I0OO
100
10
75c
123m,
• ur • HI
1975 1976 1977
Fig 16. Man-made radionuclides detected in Sweden mid-year 1975 tomid-year 1977 that did not arise from any known nuclear explosionstest. (Parts of the 1 3 1I and 1L)0Ba detected in February and Marchof 1976 should be due to the low-yield Chinese nuclear explosionof January 23.)
>*°Ba
Sampling period Grindsjön Ljungbyhrd Crindsjön Ljungbyhed Grimlsjön Ljungbyhed Grindsjan Ljungbyhed Notes
Feb 2 -
Feb 9 -
Tcb 16 -
Feb 23 -
Har 1 -
Mar 8 -
!!ar 15 -
Har 22 -
Mar 29 -
Apr 5 -
Apr 12 -
Apr 20 -
Apr 26 -
May 3 -
May 10 -
Ilay 17 -
!lay 24 -
Feb 9
Feb 16
Feb 23
Mar 1
Har 8
Mar 15
Mar 22
Mar 29
Apr 5
Apr 12
Apr 20
Apr 26
May 3
May 10
May 17
May 24
May 31
535±17O 730*290
490*150
320*110
340*100
260± 90
2O30±27O
690*240
860*340
320*110
159*40
134116
34* 9
88*11
82*12
2 5 ' 7
1053-76
36* 7
118115
25* 9
80*21
143*20
222*26
45 + 13
43114
270H9
177*14
38* 5
20? 5
33- 4
411 7
121 4
173*13
3 2 + 4
681 8
17+ 4
350+27
67* 9
44* 5
29* 8
94*11
78tl9
712*51
691+68
80+ 8
61+ 8
20* 4
39* 4
48* 7
223118
10* 3
16+ 3
1045+80
137+16
92+ 9
47+ 8
82+ 7
21+ 7
Chinese debris
} Occasion i,the I and l>a mainly ofChines ---•--•-
sion 1:-~T I and TChinese origin
Occasion 2;the I and Ba mainly ofChinese origin
Occasion 3
Occasion 4
Jul 12 - Jul 19 14? Ill Occasion 5
Table 15. Short-lived radionuclides at Grindsjön and Ljungbyhed during the first half of 1976expressed in pCi-s/kg air. Dividing the numbers by 86.4 and the length of the sampling periodin days yields the average concentration in fCi/kg air.
65
Fig 17, Ge(Li) spectrum of the Grindsjön sample April 12-20 1976.Detail, 25-400 keV with the 239Np, 99Mo, 13*I and 140Ba y-peakspointed out.
accounted for here the detection limits vary, for 239Np between
50 and 400, for 99Mo between 5 and 40, for 131I between 3 and 10,
and for 11<0Ba between 2 and 5 pCi-s/kg air.
The activities detected in February, March, and April were also
present at the Stockholm, Hagfors and Gothenburg (Göteborg) sta-
tions, while those in May and July were detected only at the
Grindsjön station. No strange increases in activity were detected
north of Hagfors (except for a weak indication at Östersund in March),
and the concentrations were larger at the two Stockholm stations
and at Ljungbyhed than at Hagfors and Gothenburg. A study of re-
gional wind patterns during the periods of interest showed that
all five events occurred during weeks when north-easterly or
easterly winds prevailed for at least two days, indicating that
the material arrived in Sweden by way of southern Finland or
66
western USSR and the Baltic Sea. This is supported by observa-
tions of 239Np an(j 99j|o £n Finland on two of the occasions
(Castrén 1977). Activities of about 5700 and 1300 pCi-s/kg air,
respectively, were detected at Helsinki during the week of March
8 to 15 (occasion 2) and higher values were detected in the week
of April 6 to 19 (occasion 3). At the time of the first event
the sampling unit in Helsinki was out of operation. A more de-
tailed study of the samples from the Stockholm station on the
first two occasions revealedthat the nuclides arrived between the
afternoons of February 20 and 23 and of March 12 and 15, when
the weather situation in both cases was characterized by easterly
winds.
It is interesting to note that the measurements of gaseous tri-
tium at Hagfors, run by this institute, showed two distinct peaks
between March 12 and 15 and between March 19 and 23 of 1976
(Bernström 1977). These events coincide very well in time with
the second occasion on which short-lived radionuclides were
observed even if they could not be correlated with very high
levels of 239Npand 99Mo at Hagfors at the same time.
The 239Np/99Mo activity ratio in most measurements varies between
2 and 4, which is compatible with ratios in bomb-produced debris
during the first few weeks (the ratio decays with a half-life of
16 days). Irradiation of natural uranium by thermal neutrons re-
sults in a 239Np/99Mo activity ratio that is larger than 10 at
the time of irradiation and takes about one month to decrease
down to 3. If natural molybdenum is present in addition to the
uranium the ratio can vary freely below 10, as 99Mo is produced
by neutron capture in the naturally abundant isotope 98Mo. Also,
if the uranium is enriched in 2 3 5U lower ratios will result.
Ratios of 2 to 4 are consistent rfith 2 3 5U concentrations between
4.4 and 2.2 percent, which covers enrichment used in light-water
reactor fuel.
67
If the 99Mo found originated in a fission process, which is sug-
gested by the presence of 131I and 140Ba on the third and fourth
occasions, as much as 12 and 17 weeks after the weak Chinese ex-
plosion, it is strange that other short-lived fission products
such as 132Te (half-life 3.25 days) were not detected along with
the 239Np and 99Mo. Mechanisms of transport from the source to
the atmosphere and to the samplers can alter nuclide relations
considerably, but the measurements show that 99 percent or more
of the * 32Te that would be expected from the 99Mo was missing.
A natural conclusion is that the 99Mo was not directly produced
in a fission process. It could, of course, have been produced in
some laboratory work on fresh fission products, but it could
also have been produced by neutron capture in natural molybdenum
used as construction material in some kind of a nuclear fission
or fusion device.
The only sources within Scandinavia that could account for the
observed activities are the nuclear plants at Oskarshamn, Barse-
bäck and Ringhals in southern Sweden and the research reactors
at Studsvik (about 70 km southwest of Stockholm), at Risö in Den-
mark, and at Helsinki in Finland. However, none of these reactor
stations a research laboratories reported any airborne effluents
during 1976 that could be correlated with the 239Np and 99Mo de-
tected.
The highest concentrations measured at Grindsjön would be com-
patible with an annual discharge of the order of 10 Ci from the
closest nuclear power plant, the one at Oskarshamn, 200 km to
the southwest. However, during 1976 less than 4 mCi of airborne
2 3 % p was released from that station and no discharge of 9gMo
could be detected (<0.1 mCi/week). Airborne particulate effluents
from nuclear power plants are usually dominated by il*0Ba, 89Sr,
1 3 1 I , 58Co, 60Co, 134Cs and 137Cs of which all but 89Sr are y-ray
emitters (UNSCEAR 1977). As most of these were not detected, and
no one was predominant, an ordinary nuclear power plant does not
appear to be a very probable source of the activities observed.
68
No atmospheric nuclear explosions were reported during the period
of interest and the underground nuclear tests that were performed
cannot be correlated with our findings. Furthermore it would be
very unlikely for 239Np and 99Mo to be the predominant nuclides
released by such a test.
As the observed events cannot be readily accounted for in terms
of any known source, the speculations in the summer of 1977 con-
cerning charged particle beam experiments at Semipalatinsk in
the Soviet Union raised an interesting possibility. The discussions
started with an article in Aviation Week and Space Technology
(Robinson 1977) which among many other things suggested that the
experiments involve "large releases of nuclear debris and radio-
active tritium". The idea is discussed somewhat more in De Gaer
1977, but since no conclusion could be drawn it is not repeated
here.
75Se
In the weekly sample taken between September 6 and September 13
1976 at Ljungbyhed 12 ± 2 pCi-s/kg air of 75Se (half-life 120 days)
was detected. During several days of the week rather strong west-
erly winds were prevailing (up to moderate gale) in southern
Scandinavia, indicating that the activity, if not resulting from
a local release, could be of Danish origin. Obvious sources of
radioactive selenium are hospitals, where 75Se is used for pancreas
scintography. but the activity could also emanate from different
experiments where 75Se has been used as a tracer. By comparing
with experiments and theories of atmospheric diffusion and
transport summarized in USAEC 1968, the minimum release needed
to cause the dose detected can roughly be estimated to be about
5 nCi at a distance of 1 km, 0.15uCi at 10 km, and 5uCi at 100km.
69
12 3mTe
Between 10 and 11 am on November 6 1975 about 30 yCi of 123mTe
(half-life 119.7 days) was accidentally released in connection
with the burning at Studsvik of some material that had been used
at a hospital in Stockholm. At the time the prevailing winds
were south to south westerly 3-5m/s, which made it possible to
detect the activity at the Grindsjön and Stockholm stations 44
and 76 km north east of Studsvik respectively.
The weekly sample collected at Grindsjön between October 31 and
November 7 showed 120± 10 pCi-s/kg air of l23mTe, a n d from t^e
three filters of that week in Stockholm it could be confirmed
that 123mTe was only present in the last one, being used between
the afternoons of November 5 and 7. Two weeks later between
November 21 and December 1, 123mTe w a s ag a£ n s e e n £n the Grind-
sjön filters but then only in concentrations about ten times
lower, 10 + 2 pCi-s/kg air. As no second release occurred at
Studsvik, the early November one was probably the source of
this activity too.
The 30 uCi discharged from Studsvik, spread by a few m/s south-
westerly winds and resulting in a time-integrated concentration
of 120 pCi-s/kg air (~150 pCi-s/m3 air) 44 km away, yields a
time-integrated concentration to source strength ratio times
wind value (4"u/Q) of around 2-10"5 m~2. This is about one order
of magnitude higher than the theoretical and extrapolated experi-
mental maximum values (USAEC 1968, Hilsmeier et al. 1962) published
for the neutral layering of air which was predominant at the time.
131I
Apart from the 131I activity (half-life 8.05 days) detected in
connection with the 239Np and 9gMo activities or any of the
Chinese nuclear tests, radioactive iodine was also detected at
70
Grindsjön, Stockholm and Ljungbyhed on a few other occasions.
The sampling times, sampling stations and doses detected are
listed in Table 16. As 131I is frequently used at hospitals no
attempt has been made to trace the sources of the activities
detected.
Sampling station
Grindsjön
Ljungbyhed
Grindsjön
Grindsjön
Stockholm
Grindsjön
Sampling time
Oct 31 - Nov
Nov 21 - Dec
Dec 1 - Dec
Aug 9 - AUR
Jan 31 - Feb
Feb 21 - Feb
7
1
8
16
2
28
1975
1975
1975
1976
1977
1977
131
12
21
10
5
660
145
t
t
t
t
t
t
t
(pCi-s/kg air)
4
6
3
2
40
15
Table 16. Traces of 1 3 1 I , probably emanatingfrom hospitals.
The iodine detected in early November of 1975 coincided with a
peak in the atmospheric tritium gas concentration that was be-
lieved to b3 due to a venting underground explosion in the USSR
on October 21 (Bernström 1977). Short-lived radionuclides, be-
lieved to originate from this Soviet underground test, were
detected during the same period in the United States (Thomas
1977). However, careful analysis of all Swedish samples from
late October and early November revealed no other fresh activity
that could confirm the origin of the iodine detected.
71
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75
Sisefsky J: Debris from tests of nuclear weapons. Science 133
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77
APPENDIX I
Activity concentrations at Kiruna, Ljungbyhed, Gothenburg, inStockholm, at Grindsjön, Hagfors, Lycksele and Östersund (Tables1-8).
Numbers appearing in the upper parts of the tables denote thefour-week average ground level air concentrations of radionu-clides measured in fCi/kg of ?ir (not Grindsjön).
Numbers appearing in the lower parts of the tables give the de-position of radionuclides in pCi/m2 during each four-week period(not Hagfors).
All dates given in the tables for the first day of the sampleare the dates prescribed by the sampling program (Mondays). Whenfor some reason the date has been changed, this is indicated bythe number of days (d) or weeks (w) that shall be added to, orsubtracted from, the prescribed dat to get the actual one. Allconcentration values are corrected for decay to the middle ofthe actual sampling period.
4 -»»k p.
1975 DecI V r
1976 l.wK b
N.irA p rMayJ u n
J u lA U K
S.-p
O c l
Nnv
N,wI V c
1977 J J I ,
F«bM.ir
A p rH.1JTJ u n
U l2 92 6
2 12219
1?14
120 90 6
04 <-M)0 12 9272421
21
in161 )
'te
36.1)5.030.647.640.150 9» 7 . 758.542.957.336.655.110.235.427.034.725.955.612.53 6 . 134.a
<0.01<0.(ll<0.Ul
<0.01
<0.0l
0.0)0.020.01
<0.0l0.O10.010.090.10
<o. i l0.(110.030.07o.oa
0.02e oi
<0.0l0.01
6.503.390.970 410.560.852.945.21
1 1 . 110.a
" M o
o.oi0.01
3 . 4 5
4.592.54
0.570.742 . 1 22 .995.074. CO
" " • * „
0 . 2 00.19
0. 180..' 7,) . . ' 3
O . ) l0.510.15
0.200.17
0.34
0.430. 370.1»
fl. I»n.320.89
1 . -t J4.966.13
" S i ,
0.040.0»U.l1»0 . ) *0.060.08o. 130.10O.Of,Cot,0.03
0.03o.nrn.m' i .n lO."l
11.1110 190.48
0.63
' " 1
4 .0 )3.45Q.06
1J7, , ' " C t
0.100.10
o . i u0.16
11.15
0.220.380.270.18
0. 16O.:i60.11
o . i oII. 100.0"»l>.060. 07'1.190. 2t0. 700.88
" " a .
0.03
8.472.560.61
O.riS0.040.03C. 02
'-It,
0.020.01
7.14
4.461.77
I I . -4[)
n. /.;i . l i1.512.421.77
» " O
0.140. 130. 31
0.45n. i'i
0.510.73
0.52
il. Jl0.250.10
1.3i0.92
0. )8
0.150.230.4^
1.61
3. °1 t9 . 1 5
1 1 . 5
'"'S.l
3.180. 36o.n
' " r
0.010.020.010.01
0.020.010.01
0.070.(1711.09
"N,00
17% Dre
l>cc ?9»76 i.i
F*b 21
Mir 22
Al-H t
InJ uAu
5v
OcNo
No
Dec*i7? l.i
F r tHa
Ap
r 19 <-1w>W
> 1412
i 0«OH
(K <-tw)0179Jt?421
21
19
\7 |
IS%
174i*>7« 5*>HI
1R !(9 1 4
) » «7R*I1 1 9Ulh
K )1!'4">4^
ft»9
n;o
5S.7
42.1
2565b 91 . 51 8 . 9s M
2 : . 't
86.22142 7 46 2 4
1. (•1,7.53 ) 1
6.(13•..)fl
.'H.570.J
11,61 '.122»
• 0
1 1 '.1 1 0
1J6
2. Vin. H7
• 510' 4(16
7510
39855.2
5.'. 579.2U . l10.3
1. 791.'. 41 \ 6
M18.10.
9.i.
4 j .
311.'4^ 1t2
••i.i
15.1
12.43.29.6Id.610.7.6 1.717.1IV. 121.71H.220.7
1.525.224.020.1VI. 9fc». 327.7
Appendix I, Table 1. Kiruna four-week average ground level air concentrations in fCi/kg (upperpart) and deposition values in pCi/m2-4 weeks (lower part).
1975 Dec Of1976 Ian
FebHarHarAprHayJunJulAUK
S»P
Newnee
1477 Jan.IanFebMarAprMayJun
OS020129262421191613U080603312»28252320
» t i n . '«e
41.2V . I4. ' . 446.442.060.262.460.91.8.166.248.4S3.132.328.033.938.836.645.262.355.761.4
<O.01«0.0l
<0.01<0.01<0.01<0.01<O.OI
<O.OI0.090.C2
<0.010.010.(120.120.170.21
0.0 .0 .0.0 .
0102111416
0.02(1.0?0.040.01
0.5114.*
3.040.771.590.8]2.8S4.16
17.920.219.6
0.100.01
0.4314.05.721.720.120.742.142.609.40S.426.93
0.240.18(1.250.2ri0.290.400.410.370.200.160.10O . M0.610.270.150.19O.»»51.276.739.38
11.9
• ' 'Sb
0.(150.04(1.060.116((.070.100.11O.M0.050.050.03
(1.020.020.020.08o n0.6U0.931.19
M l ,
0.100.O9
6. 510.20
0.0]
' "Te
0.110.120.170.170.210.120.150.100. 20o . i ;0. 100. 190.110.1180.070.090.1*.0.210.5(41.121.66
0.150.050.01
21.62.51O.W.0.190.080.080.04
0.20
0.7J20.14. 771.200.570.441.181 .584.894.21 •1.02
0.410.140.520.4]0.480.610.690.590.2!11.180.201.160.870.290.220.151.122.43
12.618.522.0
5.160.18
n.m0.01
<O.OI0.010.010.030.0?
<lt.olO.U]
<0.0l
0.1120.090.120.18
1.69
0.11
197S Ber1976 J.i i 1)5
Feb 02HaMa
0129
Apr 26MaJ i »J u
24 (-1»)> 21 (-U1
19Au t 16Sep 13OcNoUe
1977 JarJarFe>r laApiMa)J u .
11080603312628252120
19jOS324 IS
I860143028901330
775I96017J0160015301140969
14202 54013M>22402M01540
1.454.196.834.63
1.421.50: . 732.67
169 313045410555.315.225.9
120' 151
369408295
27.4
42.1
31664417844.919.133.3
1481 1?y »302132
9.63
16.210.}
14.711.1
5!.954.7
2153342 0 9
4 : 1
3.33
5.6211.11 ) 411. 3
111, I " , ,
9.06
15*010?26.2
1J'C» '»°Ba
9.1124.011.29
12.49.90
16.1ft. 875.916.186.97 1650
11.11 1290<.. 55 114J.471.256.12
12.614.141.4511.5sg.9
i-'c.
1125611)2
41.08. 11
11.050.96 7 . 8
I(<454.1 •51.8
i ^ o ' » ' N J
15.915.710.52IS.622.915. 1b. WR.O1».51
.'1.4 15595.8 15712.5U.O50.012.2in. i
i n2*9252190
0 1O.fl1.10
2.63
2.49
31.1.0 .
11 .6.1
28.10.74.29.26.23.18.V>.46.10.11 I24.4 0 .
11.555.7
Appendix I, Table 2. Ljungbyhed four-week average ground level air concentrations in fCi/kg(upper part) and deposition values in pCi/m2>4 weeks (lower part).
period i ""Ru •<"•«»
I97S Urr
197» .l.in
M.ir
M . r
A p rM-.yJ u n
I.ilAne
Sep
n. t
N.»vI V r
1977 I mJ a n!>;>Mar
A p rti.iyJ u n
OS05
01
2»
2624
211916
nnoa0 6
I I )) t2 »
2»
25
2320
43.037.9. J . I; v i
51.2»«.O
54.1(.1.151.»(.7.243.»
55.»
!4.J25.*20.92» 025.412. 641.4
33.133.J
<n.oi
< 0 . t l l
<0.0l
*0.()l<0.01
<0.0l<0.0l
0.08
0.02<0.01
<0.010.02
0.H7
0.090.10
<0tj
a00
.01
.01
.07
.0»
.L'S
0.(12O.II20.040.02
<a.oi
O.l>7
14. J2 . 1 5O.*70 . 5 5
0 .521 . »
2 . 6 1
11 .»
1 1 . 29 . 5 2
10
01
25
S873*1W4^39
12
2174
)<•
i.J*.i. .M1.27
3- ?B
J . 17J . HJ.lft
) .*A
k *>3I. ?\t. K)
J. 1 3) . 4 11.81
.4.»
i. 26S . 6 2
u.otn.iH0.(1
0.1»Q. 12
o . i t a
0. 10. 1IJ.O
o.o<
O.'»<!».(>
I I . i'ii .">(I.US
u.uf) . S
1 . %
j.MIo.2s
ooo
.14
.1»
.17
.2'.
.1.1
.11
.11)
.10
.11
2.48
19.7
2.25
O.(J)
0.04
0.11
0. 11,
O.**l
0.9S
3.25
2.3)
1.4S
0.46
0.41
0.S4
0.ti
n. j
II 2
0.7
3.0
O. KS
0.7
0.1
0.2
1.54
10.)
lo.a
I97ft Un 05 (*?d)
i'fMaM.i
Ap»l . l
Jul u
A i
S-tOr|Hov
Dre19>? l:in
i.llf>bM,
A ( i
M t ,
Jut
0?01
29
26*4
211 (*
1 1
11
11uti
• 4
H.?*<
j ^
?3
20
5H2
99^
t tnIMU
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211Tit
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1 7."' 1•)H*tl)
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4M
n?n1 I"O
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2<i K i
. i'«n
7.H7
1 . 0 2
1 . ft<j
i . 'V4. 1'*
5- Ib1.48
1
1t
1
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. • S M
. : n
.n
hu.O
l*i < u
lt>0
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I i W
1
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1 i)1 S . • r i
J O 4
33
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2 J 1101
.38
.4
.0
8. 1919.6
31. \
A4.0"i ' . 7
;n?3^
1 11 t
It
• 2 1
.B
.8
f,
in
l 7l
I
319
2*i.
1 1
;.')
?K
' C ,
. 7 '.
. U
. 7
.9
.'•
. ' ! • ;
t
2 )'.<)p ;HRh
1h
. 7
1 1 . 6
7H0
3 ^ / 014^
3 . . ' B
i l . O6 Ku
2 2 4
21». 1
:*..oi»-, s
1 1 f>
*>?. >1 ii.
' : » . . 1
,
1"17
1211
\'J2 Hl.
4 1
:
1 ^i ?
h>A
« S
IS'*
.' • 2
1H1
>
^£.1
M75
,n
U
s
Ib *
HH
4 ?h
2t>
•-U
.9
.6
1 ' ' i.u
o, }
3.O8
• ' ' - 'u
1
V42
••t.
'.
111
1 iL
• •
' ,
j
. 4
.0
• - 0. 4
. J
. 01. 3
. 0. h
>• ' •
- 1 .
Appendix I, Table 3. Gothenburg four-week average ground level air concentrations in fCi/kg(upper part) and deposition values in pCi/m2>4 weeks (lower part).
4-week period "••••sb
HJS Dec19'» .1.™
F r b
H a tA p r
May
.lulA u «Sep
O. tHovDec
1977 JanI V *
H a rA p rHayHayJ u n
IS1209OS0501) l2a2 6
23201»151)to07070»0230 (.2d)27
42.148.062.449.954.}
106»4.4•0.670.276.974.457.529.924.562.033.357.131.»76.a45.443.0
<n.oi<n.oi«0.01<0.0l<0.010.010.01
•cO.01
0.010.0»0.01
0.020.030.16O . U0.14
0,020.02O . U0.110.10
0.020.0)O.O)0.020.020.01
<0.01
5.6416.42.080.481.020.683.504.29
23.115.1P.8
0.11o.tx.0.01
1.5411.5
4.251.021. IS0.1.22.652.72
11.96.3«4.0»
0 . »O.?1*O. 410.2*0.120.710.510.410.230.15
a.i>0 . -.90 .16(1.27o. l«n .9 .1.1»S.4B7.757.64
0.050.O60. HIO.I*o.c*0.190.140.120.O60.05
0.01
0.040.C20.100.150.890.770.82
3. 190. 12
0.0»
7. 143.:"40.20
D.770.04
O . UD.I;11.250.180.240.540.441». 16
n.220.170.150.200. II0.15O.120.U70.220.221.2»1.17i.:-
~0.
U
0.0)0.
g.11 .
1.0 .0 .0 .
»
»8
)46
n0.08
0.04
0.220. 1 10.O1
5.5516.4
J.2fi0.66U .0 .
l.<1 .S.I
2.•
9)
0
59 'S
0.4]0.47n.f.90.450.5)1.120.81O.Mo.)l0.211.21 5.9)). I5 1.37n.fiii o.os0.180.420.111.702.55
17.314.514.3
0.0211.020.U20.020.040.010.02
0.010.14o.n0.12
1975 Dec1976 J.ut
F e bH a r
A p rHav
H J V
JUIIJ u lA U K
SepO c t
Kov
Dec1977 Jan
Ftt>H a r* - ~
HayJ u n
_
1209(18
0503 "3128262 3 <-2v)20iaIS
100 70 7
0 4
0 2
30 (>M)
197354284695
220575220
» 9 0767360»6027054U5<>6
0304 30170640
27 3740
1]
124
lo
.66
.10
.06
.13
.27 I . M
.1 4.01
2543)9114
30.340.»11.765.592.5
10115)356
1 1»(•13-»2164
11
• .a. t,
t . 6. 0
12)157216
t o t
9
2420
6
1!' i.
9 j
176'24
Ku
.29
.1A.24
.6
.1
. 1
' • • s b " ' l
3.17
47 19 1 . »
1.15 11 . !2.»2
3.0)
5.8414.528.0
n.-Te n > c ,
1i
•
t
ll
. 76'.841.041 . 7 1
.1*. 81.21. . Jl*. ).',.70.11.61
1.97.21
1.07. 9).115
40.0a .11
4.48
737 218561 34 295.0 142
1427
N
1»17164 i
6 )
. 4
. 8400
.2L
. 7 .
.8
6 116 7(16.555.46
18.211.94.29
5.0642.0 22U72.1 67.232.714.2l« . )1 »1
>0. 210.9
44 .62'>5555
Q.81
1 .00
1.494 14
105
-
5.04 . 05.0
17.027.037.06 2
55.046 0
•9.020.059.03 1 045.021 II18.017.011.021.0
117.0
Appendix I, Table 4. Stockholm four-week average ground level air concentration in fCi/kg (upperpart) and deposition values in pCi/m2-A weeks (lower part).
00
00K)
period .tarttnR ' ' 'Ko ' • ' « , •
117» Jin 12 (-VI)0» (-2*)ONHi0)] l28
l « i l
:8)5».
2M»Omo
2
oj
I7
11
. 74
. 1 6
.*»
. i2
.-•7
. (U l
. 6
G 7
?(J<i l
03
4 6>(l111 20"
40.» n . *1
14JS
IS
^26 2
S.9 1 . *>n i • :i !••«»I US1 2 * *7 U l
fc'.l1 > '
2 2 . 1
11
I
i f
1
I K
ri• > . S
. 17
». 7?4. IS
»»9
• - 2
*.*j4.-4.10. \h• i. 9. S
,s
l l ' l )
100
TO 2fi7 )
164A9.)
7.:i• i . JMl . 1f i / .4
17S114
i;6 .] .l_,,
4 ?.
12. '17 .? 7.
n .7.
7 7 .
1 «-I u 7
(ill9 7 2
Hh
1
i ) t
)57
1
'»4 )7
Appendix I, Table 5. Grindsjön deposition values in pCi/m2#4 weeks.
11.1
4 . 51.5
18.2132 .6
197S Dec IS1»7* .Ian 12
Frb 09Har 08Apr 05Ma» 03May 31Jun 28lul 26
* • « 23Scp 20Oct 18Nov 15IkT 13
1977 Jin 10l>h 07Mat 0 7Apr H4Hay 0 2May 30 ( 'JdlJun 27
30.13i .a36.544.048. S83. 364 . .60.071.6S I . )54.231.121.122.021.S35.927.838.9»8.0St.632.6
<0.01<0.01
«0.01(1.010.01
0.040.02
*n.ul»0.01
<0.010.03O.lf0.170.10
<0.0.0.0.0.
I l l
(120914M
0.010.010.02
<0.01<0.010.01
0.356.671.350.4S0.360.801.754.94
14.118.09.14
"Mo
0.0?0 02
«0.01
0.414.99l.L'H1 .oil0.410.701.273.047.357.353.11
0.150.170.250.250.320.560.430.340.21U. l lU. 14
0.170.1)0. ! 1
O.ll*
0.2U0.^7l.SB5.109.106.07
0.115o.n't0.050.060.090.150.11II. 09O. I*0.04
0.01O.nl11.11)0.06II 160-600.9)0.61
0.
1 .10 .
07
5546I )
0.100.12 0.130.13 0.050.160.230.4)0.35n.?0.20.1
\
O.O'I 1.910.10 6.27O.IKl.n
O.I)0 .01.1l.2f
0.71.210.8(
1.190.200.0+0.O60.040.02
0.030.04
1.087.6)2.760.67O.)2U. 4*4
0.»)1.703.6H).441.29
0.290.))0.4)0.420.510.860.650.470. in0. Id0.291.480.5»0. 19(1. 1'.11. )"•0.1")2.97
10.9' 17.)
10.9
1.001.49
0.01
0.010.010.040.020.020.02
<u.nlO.IIJ0.090.140.08
Appendix I, Table 6. Hagfors four-week average ground level air concentrations in fCi/kg.
oo
p*i l(Hl at-arring
l">75 OreH76 .Jan
07 (»Mlm
»prM-iy
1! ("Id)
04
41.')5
6S.V..
<0.010.01
<n.ni
«o.oio.oiC J . 0 1
0.04O.IS
0.1»0.12
0.020.01
I). 7-.•..2)1.16O.'.lo. yi1.0«2.BO4.9O7.94
IV»
.20.20
1. 24.74
I..*».45
.24)7
0.040.04
U.I*0.07U.I 70.120.0*0.060.02
0.O20.01
o.u0.8i
7.I>J0.860.13
o.no.uo.n0 . 1 60. ?00.4H0 . 3 50 . 7 50 .22o . im0.120.12o.n«0 04
0.14O.Oi
14.5•.14
0.770.T50.061.O6
0.02
"••(>
0.040.02
5.442.000.7)
0.1110. J7n i]0.1)
o. 1U. 1 11.4)1.05O.'.0 .2 )0. Irt0.5H1.41.
h. 2715.K
''•'•EU
0.010.010.04
' " I I ' N , 00
O.OiO.I )
1976 l.in 11
Vp 270.1 25N..» 22iict O
1 ' in 17>Vb 14Mir U«[. | U i
229150f.*0
7.25N47 1 6
53»111010)0
9 » !
1900
I .2 .S .
57344 6
4*»5«• i
1!)
I , .
1 U
. i0
. I
. 1
8
l r . 1
5 )I ' . .
1 1 .
1 ) .
1 •?
i n1 39
721
i .'. 07.20
hl 'I9.'.7
l a c
.••6. 7
1 1 . 4
7 . 9
51 2 .
2 . Oil
S. i ' l
4 . 7 1o . l
S . O6 . 4
1 2 . 41 0 . 8
7 . )1 5 . ( 1
2 5 . 210.811.211.514.(169. 721.24). I IJK.J-5.542.7
Appendix I, Table 7. Lycksele four-week average ground level air concentrations in fCi/kg(upper part) and deposition values in pCi/m2>4 weeks (lower part).
»-vert per "Mo •»•l.
1915 Dec19>* Jan
FobMar
A p rNay
J « nJ u l
A U K
A n *
Scp
P e tNav
Dec
l»7J J.-mFeb
P.i tA p r
221916
IS121007OS0 230272522
2 0
1714
1411
29.933.2»0.2»1.6»1.973.6S l . l55.276.236.063.225.029.418.»21.1»3 .336.0»4.7»5.718.0
<0.01
<0.01
0.020.030.01
<0.01<0.01
0.050.100.08
<O
0p
00
. 0 1
.01
. 0 !
.10
.07
0.01
0.02
».173 *81.2»0.310.331.781.878.17
13.68.90
<0.010.02
2.1»4.9»2.'»20.610.]41.561.41».126.493.4»
0.150.20fl.?10.240.260.500.301.25(J.2I0.100.190.400. }b0.100.050.420.S I2.7»5.SB».69
0.040.05n.us0.050.070.130.09o.ott0.07
0.02
0.020.01
O.IK.n n*0.290.510.47
0.090.120.140.150.170.4U0.260.240.210.060.100.010.090.040.030.12u . W
0.440.790.6*
0 .
0 .
6 .
3.0 .C.
0.0.0 .
113
0»
• 4
7384
' 5061 00 3
0
»520
010
231
.01
.64
.11
. 1 7
. 4 3
.28
. 0 3
. 81
. 7 0
. 11
.58 '
0.270.350.400.390.4]0.810.4%11.410.320.090.850.870.440.12
a. i»0.781 .005.18
10.68.99
3.010.56
<0.0l
0.010.010.020.020.01
0.050.080.07
»-week period •lartLnB. 7B« "Zr "Mo
1975 Me197k la»
FcbM * r
A p rMay
JunJ u lAuCAur.Sep
O c t
NnvDec
1177 JanF r b
H.irA p r
M.iyJ u n
! 9
1615| J10070 50 23027232220171»U11
0 90 6
312611188224524
217U2510
5U47(15565 0 .»«»M l2613133(16
l»«0844
2530
2.221.906.03
1.09I . » )5.71
19117735.915.359.71!.621.6
21713762»
12.»10.1
0.95.08
51526
189104HI
.54
.2
. 5110
95 .0323
7.517.34
23.7
Jl'J24.7
1.) .1.1.».
11.12.
1 .4 .
I.2.3.1.0 .0 .2 .
IA.16.67 .
5073743771B2H42115>41»
a)7
3
609151
223209
S3.1?.
4 .
5.in .; i.4 ) .
I l l
3.9576205
4 .409 .883.114 . 9 ]S 19
16 .415.1
2 .16l . b l )
35 i45. 113.5
5 . 3 ;4 . 4 65..'6
17.7139154631
13136.9
6.36.67.8.'2H.22.26.14.26.9.114.715.625.230.138.2
Appendix I, Table 8. Östersund four-week average ground level air concentration in fCi/kg(upper part) and deposition values in pCi/m2*4 weeks (lower part).
oo
87
APPENDIX II
Quarterly depositions of 137Cs in mCi/km2 (=nCi/m2) 1961-1977.
88
i » .
ms
19b»
1«»:
i»66
;<.h9
1970
1971
1972
1*73
1574
1971
197*
197?
.
1234
1234
1234
t:)4
t23•
1234
1234
1234
1234
1254
1234
1234
1
254
12341234
12
0.21
0.14: .ob2.390.26
0.211.759.US1.07
0.3»3.766.940.60
l . l l1.471.700.01
-0.140.74
o.oa0.070.140.310.040.010.710.340.05O.Oi0.090.290.O2
0.020.320.530.04
0.O20.360.560.01
<0.010.10o.oa
<0.01
<0.01U.030.04
<0.01
<!).O1r..i4;.39
O.OI
0.01
o.oa0.0J
CO.01
0.00500.00760.0140.0076
0.00680.093
0.26
0.3»I M SI B S0.39
0.244.397.501.22
.59- .95).!90.600.541.321.540.16
0.170.4<iU.93r. 16
0.140.370.200.06
U.04
0.720.4»0.05
<0.010.110.08
<0.01
<0.010.040.O3
<0.01
0.010.070.26
<II.O1
<0.010.040.04
<0.Ol
O.OOIU0.0120.O140.012
n.0100.076
0.12U.03
0.010.070.10
<0.01
<o.o:O.Oi0.04
<0.01
0.010.130.290.01
0.020.050.04
<!).O1
0.00720.016
o.on0.0189
O.O1420.094
0.OO78j.012C.0170.021
0.0160.073
i .Ot
1.544.094.91n. 93
O.Bl8.199.951.64
0 .524.«»3. 10!. 30
: , . ' ;: .o°: . 2 6'_.5O
0.601.110.47
".?!O.iO0. 390.11
C 0 8
Cl. 29
'1. 71
c.:o0.12o . i »i-. >i0.11
a. iir .4Oo.5«c. i ;
0. 140.400.480.06
0.0)0.11i i . l l
<r..oi
< .010 .031.01
<ii.01
0.010. 14o. :20.07
0.05
o.os0.05
<o.or -1.H087o c:5O.t'19i 027
u.0211,123
0.87
1.403.514.021.16
1.046.50
17.655.67
2.022.095.87J.19
0.942.632.02'0.47
\.Z20.890.500.27
0.310.26C1.390.14
1.100.53';.S1
-
0.4)0.290.08
0.070.700.770.16
0.21G.470.540.10
0 04o.:i0.110.01
0.020.04
<1.01<o.oi
0.040.160.18O.oa
0.100.080.03
<U.O1
o . r i i0.03*0.0110.046
0.0290.113
-
-4.544.021 1 0
0 927.43
1.' .683 42
0.805.114 . 7 4
; .O4
0 .672.35: . 6 2'i.66
0.511.100.90S.30
0.490.560.310.17
0.231 .54c.?:0.19
G.130 . . J0.220.13
0 . 1 .11.430.780.21
o . :5r .69n.560.15
0.010,210.140.02
0.020.06U.01a.01
0.100.130.170.10
0.120.120.06
<0.01
0.0190.0400.0210.021
o.n?40.129
Appendix II, Table 1. Quarterly deposition of137Cs in mCi/km2 (=nCi/m2) 1961-1977.
89
APPENDIX III
Activity concentrations in ground level air measured in fCi/kgof air. Weekly averages at Kiruna, Grindsjön and Ljungbyhed(Tables 1-3).
All dates given for the first day of the sample are the datesprescribed by the sampling program (Mondays). When for some rea-son the date has been changed, this is indicated by the numberof days (d) that shall be added to, or subtracted from, theprescribed date to get the actual one. Before December 1 1975most dates are corrected 3 days, as the weekly samples of theold program started on Fridays. All concentration values arecorrected for decay to the middle of the actual sampling period.
O7 (-LI)14 ( -Ml.'I (-111!?K0 *11
I f )2 *
0 1Ort15
-3<l>
-w>
- i 1)
-3.1)
22 (-)J)2* (-)J)r» (-Uj1) l-W)20 1-3.1)
U)1017 (-Jd)24 (-3d)010»1522
051?11 (-3d)
23Cl08IS
Hay Ul
Jun 07 <>M)
211*
2I>.4
f>7.3
St. 25». 53S.2
32.32». 7
15.241.951.72H.))•!.»
»5.3MJ. 121.111.)V.25<..2St.)11.419.83J.5
47. S12.135.05 - . '»lO.O
;o.ofel.4? 1.145.017.31».74».OM - •
7**.4IS it.H.1411.551.241.0
n u50.040.040.02
0.)»0.1)0 . 1 7
0.040.05
0 .0 .
0 .
n.n.0 .
0 .
11<5
! )
) J
0.04
).02
0.0]
0.02
2.?S1 . .' •.1 . ( ' i2. .'fii . ?•*
2. M ;1.2;0.7'.n. A*I
0 . :»
0 ! »0.180.30
f 1. ; ;
0. 2H«', 17
0.23
') . 16U.2S0.130.39
0.07
0.15
0.2S0.24
0 . 1 /f i . i2U..D0. .20 1^
0.170 . 1 <*0 . 1 5
U. )70 . ?^
0. )*>
n.210 . 1 50.1180.U4
0.07(J.Ufc
O.uiO.n7
n.os
0 . ' * '*n.u7U.050.05
0.04
O.'Ji0. nu0 .U711.11?fi 1 r,
n.2i0. 11o. vn. w»t l . %••
f t . 2 *
0. iy
(I.)}
II. AS11.740 . 4 J
o.:h
0. II
'..140. 1 1M . u 5' I . 111 . 1 7('.Of.
0. !1
O.dA 4. ,*"0.02 2 .580.02 2 . " I
2 .551 .5.0•I.K2
n.dH0.47O. -'i0.72
0. U'*0 . 1
1 . ]#>
) . ' '
O.I) ' .
?. ' !
>. 1'I.Ci0. 1).lf> 0.16
0 . 1n. ]
t . ?
•-. i
n.J>.J
>. )" . 1
1 . |
f>. 10 . 1
0.04
0.12
0.03
n.oi
00
00I - .
( >
nn0
i )
0 .0 .00
00
00
0IJ
00
46
. ' !
V
J241
5 1*.'}ht
: 18( 4
1.7
i 54 'r>4
11.07il.O)
0. Oft0.04O.CM
0.01
0.03
n . *>*'I. O0.38
Appendix III, Table la. Kiruna weekly average ground level air concentrations in fCi/kg.July 1975 - June 1976.
Uret
Jul
"Mo !>;„os12112*02
2110O*11202704(-M)11IS250108152229nt,
1?2*1107142129071421
2a0411II2i02n»]•>
21TQ(.ld)nt112022
7J.171.246.1:».»
10).070.»51. 62S.510.t54.7*>.«14.2» . 0»5.181.21J.219.035.725.126.720.711.461.228.13 1 . 2
28.»14.»28.216.1211.515.4K.941 .151.041.12J.»15.080.173.2Ii.»4 7 . 846.?75.729.15292». 72 * . *19.5)1.514. 641.2
0.100.020.010.02
0.02
0.020.010.02D.020.010.0»0.040.10O.»O.C*0.120.210.0»0.12
0.01
0.020.02
0 .02O 04O. ll>0.1140.U90.060.05
o.n0.190.050.10
0.272.51
20.5.99.52.49.12.09.80.25.4
0.40.50.4'0.20.4-0.50.410.4O.A0.801.141.8*1.161. «.4.0»1.003.073.71t.42
15.01• 6.2111 .7
8 . 1 17.77
1 5 . 025.7
6.7412.9
0 .0 .0 .
0 .
0 .
0 .0 .
4 0I1*26
19
14
1811
0.10n. loO.IK,
0.060.120.070.010.02
0.0611.91
10.51.104.195.825.50
:'. »aj.iil .B i; . 321.150.81)0.1)0.560.660.420.500.640.74l .dl1.561.111.163.082 . 1 12.082.1»1.838.453.256.7)3.161.456.48
10.42.69».71
0.21
0. 19O.Vi0.400.54
0.110.410.50O.?O0.170.11
0. 14(1.17a. :oI).100.170.18(.. 100.470.370.411.221.011.001.322.315 . ?2.425.551.741.247 . 1 1
11 .01.741.84
0.05
0.04
d.Oi0.040.01
0.110 .12O . H
0.110.200.540.240.510.1S0.190.681 .140.170.7»
41i ;
67
.»12*.8(1
4 0191 1IS12
)3
o . ; i0.491.50
0.140.11O . U0.080.170.300.190.130.060.010.090.09
(1.07n.(>80.210.070. 100.120.110.09O.(I7(1.100. 160.07O.OA0 . 1 *0.020.050.(170.050.060.(190.1)80. 110.120.D9O.')90 .280 .220. 160 .210.16(1.810 . 11»(1. 780.500.511.001. 8t>11.531.12
0 . 1 . '2.
21 .
( I .
78
]
14«0
s' 0SI
;
(1.8 70. 2 10.210. 190.070.12( M l
0.060.050.D60.050.060.060.020 .020.050.02(1.03
0.010.03
0 . 7 20 .57O.?90.120.290.580.310.220.07
0.180.15
0.282.75 0 .61
4.415.905.94 1.156.42 1.285.12 1.013.2! . 72 . 4
2 . 7
O.HO.H
O . h
0 . 20 . 4
(1.10. »0. >0. 50 . 1o . h
( 11.70> (1.12
0.56i O.h5) 0. .'0
0.24) (1.2!
0. 11I 0.19
0_ 2h0.21
1 0.21) 0.14
0 .42* 0 . h 2
1.07 0 .990 . 7 2 0 . 7 4
O . h1 .8
0 .792 . 5 1
1.24 1.911.21 2 .071.) 2.622 . 1 1 4 .724 .h 11.61.K1 5.1»! . *2 . C1.81.2
11.«7.657 . 5 ]
15.65.18 28 . )1 .2
2.2?8.00
15.»
ni
! 0 .
0 .
0
0
...„HI9
19
24
II. O*0.04O.M0.060.0»0.070.050.110.240.070.1S
O. 190.160.67
Appendix III, Table Ib. Kiruna weekly average ground level air concentrations in fCi/kg.July 1976 - June 1977.
•V©
Ju l
A u »
S e p
O c t
N o v
D»c
J » n
N a r
*l»r
Nay
J u n
il.irtins '
fW ( - M ) » t .14 (-3.1) J4.21 (-l-l> 528 (-3.1»
n.i .
<M (-3U) 50.11 (-JJ) 109IM (-1J> 4).
25 (-3.0 1».01 <-!,!) )
15 [-W> 422 (- U) 329 (-1J> 4I * (-3U) 1
11 (-1-1) 270 <-W> 2
\.9 .
2 7 ( - i4) 3#t.O M - W ) 29.io(-w) ii.17 <-ld) 40.24 ( - 3 d ) 37.»Ol Jfa.OB 1
i 5 5
27 224 1'15 (*2d) 4
12 419 l2*. 202 40<* 3
16 4
j .4 .-,
1 .
1 -^l . l
MM
I 0 '»g5 O . ' *» O.l>«i <•.»')
0.0*ii U.04
0.02t O.<1 >
V O.UI4 O . O l
0.0?<0.01
1 <O-01» <0.0lk
<o.oi
<0.01<0.01
1.01 .(
* . r73 44. (01 6 4 . 'Ort 115 4
(,,<
22 37.2'J 1U5 1
2.3
12 61.fl19 (*ld> 43.32« 45.flU3 53.1Hl 71 / 76. ft24 -»8. fl
31 <•*.. 207 (»14 *> 5.714 V».2
71 fcj.i28 41 . *
<O.D1<0.01
<0.0l
<n.Ql«0.0l
0.01
<0.01
o.niu i>itl.l)t
<d.f)l
• d.OI<0.0|
<O.OI
0
n• i
ot
uu0
- I U
, t » l• 1 .
. 0 2
. 0 1
. " i' )1
. n i
1.1.00. 761.04II . #-7n. vii.69il. i*.0 190.7-
0.130.13D . W0.070.040.(17o.nst-.fl5
0.030.030.05n.i»0,i>JO.(*2O.H2n.020.030.02
<n. i»l0.08O.i)*»n.o30.030.O20.010.02
0.05o.oi
<0.01
O.Mln.oi
<n U< ' • . ' » !
<U,I)1«).O1<0.01
0
00
00
10
00 .
26
22O4t
1514
:.4
5107
2004
0.?O.(
U.l
2 4.4*.t ? .711 » . ' i 1 *
0.08 2 .'.'i
O.fMi 2,02O.n7 2.1.?O . l * 2 . 7 1
. [ 1 o.:-»0 . 0 2 l .MH
0 . 0 1 0 . 7 »
0.710 . 0 2 1.35
« > . 0
o. ;
0.42O.W
i n. >ii • . ; 4
i ) . ' . )
' ) . 2'*0 . 1 ^(i.h?
n id1). 1 7
0. .'H0.140..'»0 ?*•t). 350.200 . 1?
n o.;1»o.i6 o.i;0.03 O.Vi0 . 0
O.;l0 . 00 . 0
' ( l . l lU.t)
<o.o
2 0. 14) o. ;-41 0.12i 0.2S
0.22O. i\
o .250.40o.n
1 0.15O . I H
0.51»O.'-5O.I.'I
0.51
0.150.1' .
0.19
0.34
C M0. 150.54'.78.1.22
M./.3O . , t»
n . t )0 . l*>
O. 1 J
0.120. l*>y.o1»n.070.H7n.*i7i> i?
0. IH(1.070.070.05I I . • • *' ) .
0 .() _
1 ) .
I I .
0 .( 1 .
0.0.0 .
IS
u15• ;)#.rtr.>7)*.0
O.IIHD.(J70.07
U.KHO. 'J70 . < * i
O.d1*o.o;(1.080 .
0 .1 1 .
f l .
y .
)8
52T
1
1.11il.U11.110 . 0
1 n ,
0.02
0.02
D.020.450.29
n.obu.o i
O.U'i0.07
•1.02
0.25
0.06
0. I l0.03
1 v Ti'
0.230.05
1 i •
1 .4n . 7 ;
1.11 1 . ;
2
I I . JH
'].«•
n. 70. ' .' t . 4
0 . i
j
5
'1.29'1.4M.25!). !50 . 20. 1 7' I . i0.150.200.24». 1t . 10.1T. .n. 10 . 2
o. 10.1o n0.11 l . 180.10.20.2o..1
l . U0.130.10
0.08 0 1*).?!
1.1
) . :i..'
1.1) . PA
1. ?»1 ••.*
>. 4Lr . ' .
» . 11. U0. 1'
> . }•*
1.3*
> 0.08
0.120.02
0.01
• • • I I - , .
0 (17• l . O .
0.U7(>.".?(».'12
0.070.01
0.02
o.*-o(!>'!a.im0.^6D.«»3
O.'JI
0.U3
' • "Ce
7.71
> . i *
H.ni4 . ( W2 . ' . 7
5 . 5 * i
3 . 1 5
2 . 2 ?
1 . ^ 2
1.501.18l . n ;0. 8*0 . 6 JO.>*2
0.S6
D.180.54O.i1*f l . 4 ' »0.480.460. ' . 70.4'l0 410.4 7n.510 . 3^
n.500.920. ?h0.56n. jon 58I t . *><»
f l . J2
0 .48n.790.440.51r. .h31. »7n i;1 ' ^n. H1-*
U.641). 74
0.700.62
0.04
''-'•1
u. 100.07
11.110.060.04
0.0'(i.(u
0. ''2
0.030.02O.O.*0.01
0.02«o.ni
0.03O.Ul
O.oi<o.o:
<0.01
0.01
o.n;0.030.0.'
0.01O.fi20.04
O . O i ,
ii.r» J
0.02* ' . U l
0.02O.OI
'"u
0.»0.51
0.560.43
Appendix III, Table 2a. Grindsjön weekly average groundJuly 1975 - June 1976.
level air concentrations in fCi/kg.
Unk
Jul
fet
O c t
Nov
0 « c
J a n
F c b
H a r
A p r
H a »
Ju»
starting
0512192 6
020 916
2 )3D
0 6
1120270 4
11ia25010 8I S
22290 6
1)2 0270 )10
17
24310 7
16212 8
or1»712*.0 4
11(-Id)IS25020 9
16
2330(«ld)0 6
132027
4J. I49.744.312.S25.1sa.o56.249.)55.442.154.910.078.»14.»74.4Si .a22. a28.»24.921.416.125.427.020.738.339.a12.229.039.822.012.545.145.226. B35.823.821.754.543.25». 720.721.t40.0a». 346.096.»59.244.049.J75.141.»U . I
<0.010.01
<0.01<0.01
<0.0l«0.0l<0.01<O. 01<0.0I
<0.0l0.010.040.140.110.040.010.020.020.U10.O1
<O.I>1<0.01<0.01<0.01
<0.01
<0.01
<0.01<0.01C0.01n.oiO.010.010.020.010.010.0»0.150.140.190.110.140.160.250.1»0 . 1 *
" y
rf). 01
<0.01
<C.O1
«O010.010.070.010.0]0.010.01o.cs0.150.11o.i a0.120.120.140.200.120.14
" I r " M o
0.02
5.0» 5.108.9» 2.34
i l . 417.55.74.81
0.391.07
1
1.152.041 . 51 . 30 . 7
0 . 70 . 80 . 60.530 . 7
0 . 50.6C0 . 6
0.8!0.681.081 . 9
2.103.392.6"4.922.2a5.210 .1
[1.7Q . »
17.29 . 07 . 9
7 . 6
[6.26 . 5
a.l
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0.70. 9 6. 7 9
. 18
.57
. 17
. 12
1.12. 3 8. 2 4
. 7 8
. 1 5
. 9 7. * • >
0 .9 )0.590.890.660.98O.S)0.951.451.492.611.802 . 1 1
1 . 1 12.785.1a
11.59.51
13.08.937.807.56
11.25.99».04
0.280.400.740.160.150.230.170.210.140. 140.170.080.110.700.210.140.41)0.460.440. )H0. .,00.370.420.250.12().))0. 60.18(1.190.150.260. 160.100 .11o.770.410 .470.890.670.960.551.371.018.286.48
10.27.507.447.(0
11.17.71a.84
'•• 'si .
0.080.110.070.050.040.08O.0511.07o.040.050.050.020.04
0.(14(..030.020.010.0 30.010.020.030.0)0.0)0.U40.050.04(1.040.050 .(*}0.050.060.1170.120,110 . 1 20.110.190.160.920.691 .110.8 10.890.951.470.851.08
M l ,
0.01
4.516.2'.9.58S.571.410.82O.)5T.160. ii»0.118(1.0S0.04(1.(15(i.n i0 07(J.02o.ul'».020.02
0.24
0.02
2. IS1.640.96
0.260.44).26
0.190.160.290.200 . 2 20.160.170.180.120.140.140.140. 150.1 )0.180.130.120.100.170.1»1.080.110. 110. 1 10. 10[111D.0«D.140. 111.17).O81. ) 2>. 141. IiJ.72i. 19•>213.19J.2S3.51
. IRJ.86
. 5 4
. 28
. 2 2
. 7 1. 0 1. 10. 1 1
0.02
5.9910.674.118.9
7 .205.102.701.111 .050.740.170.260.180.270.210. 240.190. 100.08a.090.06U.05U . ()')0.070.07O.OS0.040.0)0.040.050.100.050.040.02
0.47<0.01 0.82
0. 540.280. IB0.410.270 .110.270.200.200.110.19
4.8.6 1.059 . 9 0 1 .91
7 6 . 91 8 . »
5.524.71
9 . 5 1 1.449 . 1 8 1.515 .90 1.05J . 5 5 ( . 7 1
7 . 9 2 0 . 5 6
2 . ' . 4 0.511 . 4 1 0 . 1 2
1 . 1 1 0 . 3 1
1 . ) 9 0 . 4 1
0 . 7
0 . 6
0 . 90 . 7
0 . 5(,. S
I ) . 7
! 0.77b 0.241 O.)92 0.171 0.1O1 0. 151 0 . 4 9
0 . 6 1 0 . 4 4
(1.72 0 . 6 2
• . .45 1 . 3 0
1 1 .511 . 7 ) 1 . 9 8
1 . 5 2 2 . 0 1
1 . 6 2 2 . 5 5
I . O S 1 . 7 6
2 . 5 9 4 . 8 6
4 . 1 5 8 . 9 6
2.n6 . 3
21.717.4
7 . 1 5 7,1.65 . 75 . K
19.071.4
4 . 7 7 . ' 2 . 15 . 9
1 . 1
31.720.0
1.7] 26.1
" " "
0.020.0)0.020.01
<0.0l0.020.020.02O.niO.OI
<0.0l
4.866.51
11.86 . 8
1 . 10 . 9d . 4
0. 10. 10. I0 . 1
0 . 00. 10. 10 . 0
1
0.11
0.01
«O.OI(1.02
0.0)0.020.020.1)10.040.050.17O . I )0.160.140 .110.160 . 2 )0.170.19
717 II »"«.
0.46 4.250.84 1.491.060.44
0.!'.0.150.780 . 1 20 . 10 . 10.10 . 0
0.0
Appendix III, Table 2b. Grindsjön weekly average ground level air concentrations in fCi/kg.July 1976 - June 1977.
I »
n.i- U ) Vt.»•Ml 41.4
Wl 4».k<-M> »»..•-VDID.41-MI t l . l-MI M.I:-MI kl.lI-M) I t . )I-M) M.k-M> It.*I-M) 4I.I1-MI Ik.t•MI 4*.t1-MI V>.)[-M> »I.I1-MI 44.)
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1.41
i»(.1)
Appandix III, Tabla 3a, Ljungbyhad vaakly avaraga ground laval air concentrations in fCi/kg.July 1975 - June 1976.
-rr-4
95
9 CSS JSS22
* »
S SCSKSKSS 2 t 5 S * 2i5
s*
3 S . S 3 X X 3 S S « S S S S C > *
SSS.StSSSIfSS 8
8SS«St>3
SSIXSSSftSSSS'4
88 sssrsstssas:s3s*ss
5*525525 =f2»;Jf«S
I f l i i II f l i t 4
3O
^
97
APPENDIX IV
Activity ratios in ground level air at Grindsjon Aug 1972 -Jane 1977 (Pigs 1-18).
Ataospheric nuclear tests in the northern hemisphere are de-noted by vertical lines. When applicable, decay or build-uplines are drawn for the fresh debris coapartacnt in the pe-riods between the tests. The position of these lines arebased on fission yield data for aainly Mt-range weapons asgiven by Barley et al. (Harley et al. 1965).
98
1 0 '
Appendix IV, Fig 1. 5 l fHn/95Zr.
10"
1 0 -
r
Appendix IV, Pig 2 . e 8 Y/ 9 5 Zr.
99
10 -
Appendix IV, Fig 3. 99Ho/95Zr.
'fr
r
10-
m%
\
Appendix IV, Pig 4. 103Ru/95Zr.
•"••L.
100
Appendix IV, Fig 5. 106Ru/95Zr.
10
Appendix IV. Fig 6. 125Sb/95Zr.
101
10
Appendix IV, Fig 7. 131I/95Zr.
UP:
Appendix IV, Fig 8. 132T«/95Zr.
102
Appendix IV, Fig 9. 137Cs/95Zr.
10
Appendix IV, Fig 10. l l > 0Ba/9 5Zr.
JLL--.1
103
icT-
Appendix IV, Fig 11. l l | 1Ce/9 5Zr.
idr-.
Appendix IV, Pig 12. »**C«/»5Zr.
104
1 0 -
10 -
Appendix IV, Fig 13. l l | 7 Nd/ 9 5 Zr.
é:
•fe-.
i10
Appendix IV, Fig 14. 1 5 5 Eu/ 9 5 Zr.
* w \
."•?
105
10"-
lo-d
Appendix IV, Fig 15. 237U/95Zr.
Tv*
k
10 -
10"-
KTi
Appendix IV, Fig 16. 2 3 9 Np/ 9 S Zr.
»NT
I
"i
i:
a.
fe
106
10"-
10
Appendix IV, Fig 17. 1 0 3Ru/ 1 0 6Ru.
1
i.
i
10 -
10
Appendix IV, Fig 18.
107
APPENDIX V
Activity concentrations in high altitude air Measured in fCi/kgh i le, T a tropospheric one.
yof air. S denotesEi denotes "tiae
gs a stratospheric ss 10in.
108
' $ • - .
c.
I
I
!**Huilsiu
i i i iiii i i if
? ? ! ! ! • !
i ils i i i ijiii i ; Hi
I
i
i
i
I
t
/. 1 .
Li,
liiil
iiill liiiil iliiliiil iiHiiiis
iiiiilijiiiii ssisssifii i Hii^Ii i £
iiilssil I II i
i i» i H s
s i ii i i| iii s I isi^iliiliiilzs
I j i i l i s H i i l É i i i l i i i s s I l S f i f
iiii ?ii si iH| i
i i MM??!!!
: i ! i si s!
|lli!| I ! I i i 1! i ! SS i Hi! i Iilii! i^iHillif! i § j | ? H i 1 iiiffii»!*!?'!*»^
e
2«c
I
IM
B••4
B)
O
«
§u
•H
v•o
•s
si• 8 "
•g-
109
APPENDIX VI
The stratospheric saaple collected on November 26 1976. Ge(Li)spectra Measured (from top to bottom) 13.1, 50.2, 174 and 356days after the November 17 1976 Chinese thermonuclear explosion.The count-rates are given in counts/ain and the y-ray energy inkeV.
m
110
Appendix VI, Fig l a . 25 - 512 keV.
~ " \
•Jf
111
-t
V!
b?
Ä
•s.
I
sar Asr a-
s
a" T
Appendix VI, Fig lb. 512 - 1024 keV.
s
11
i
•T - T
T" "t
112
I * . J?!'™
\
i -i•1j
m
a.
J tAppendix VI, Fig lc . 1024 - 1536 keV.
mm
t113
•XT
Appendix VI, Fig Id. 1536 - 2048 k*V.