precision neutron cross section measurements at reactor neutron filtered beams o. gritzay, v....

Precision Neutron Cross Section Precision Neutron Cross Section Measurements Measurements

at Reactor Neutron Filtered at Reactor Neutron Filtered BeamBeamss

O. Gritzay, V. Kolotyi, O. Kalchenko, V. O. Gritzay, V. Kolotyi, O. Kalchenko, V. LibmanLibman

Institute for Nuclear Research of NAS of Institute for Nuclear Research of NAS of UkraineUkraine

Prospekt Nauky, 47, Kyiv, Ukraine, 03680Prospekt Nauky, 47, Kyiv, Ukraine, 03680

The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July 15 - 26, 2009The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July 15 - 26, 2009

Olena GritzayNeutron Physics Department

Ukrainian Nuclear Data CenterUkrainian Nuclear Data Center e-mail: [email protected]

ContentContent


1.1. ActualityActuality2.2. Today situation; ReasonToday situation; Reason3.3. Ways of problem solvingWays of problem solving4.4. Short characteristics of the KRRShort characteristics of the KRR5.5. Physical basis of NFTPhysical basis of NFT6. Essential principle of NFBT7.7. Merits & Demerits of NFTMerits & Demerits of NFT8.8. Improvement of filter purityImprovement of filter purity9.9. Set of filter components in the NPDSet of filter components in the NPD10.10. Neutron filters used in NPDNeutron filters used in NPD11.11. Components of some filtersComponents of some filters12.12. Procedure of neutron filter creationProcedure of neutron filter creation13.13. Fundamental investigationsFundamental investigations14.14. MMain systemsain systems of of experimentalexperimental equipment equipment 15. Some experimental results16. New direction in NFBT (developing)New direction in NFBT (developing)17.17. ConclusionConclusion

ActualityActuality scientificscientific

Up-to-date level ofUp-to-date level of development development demandsdemands technologytechnology

the the high accuracyhigh accuracy of neutron data of neutron data


allo

ws

to make progress in development to make progress in development ofof nuclear simulation codesnuclear simulation codes generation of END librariesgeneration of END libraries

THE BASIS FOR ANY TRANSPORT CALCULATIONS for operating & future reactors for nuclear technologies in industry for nuclear technologies in medicine, etc.

Today situation Today situation

The most difficult situation with theThe most difficult situation with the accuracyaccuracy of of NCS is in the energy range NCS is in the energy range

from from several keVseveral keV to to several 100 keVseveral 100 keV


ReasonReason

The lack of The lack of high flux installationshigh flux installations for the for the mentioned energy rangementioned energy range from from several keVseveral keV to to several 100 keVseveral 100 keV

Ways of problem solvingWays of problem solving

1) Construction of new facilities similar to1) Construction of new facilities similar to ORELAORELA or GELINA with very long flight paths

Very expensive !!!

2) 2) Use of the neutron filtered neutron filtered beambeam technique at the existing research reactors


Short characteristics of the Short characteristics of the KRRKRR


The WWR-M KRR is a light water moderated and The WWR-M KRR is a light water moderated and cooled tank-type reactor with a beryllium cooled tank-type reactor with a beryllium reflectorreflector

The reactor currently uses 36 % enriched The reactor currently uses 36 % enriched uranium-235 WWR-M2 fuel assembliesuranium-235 WWR-M2 fuel assemblies, , each of which each of which consists of an outer hexagonal tube and two inner cylindrical tubesconsists of an outer hexagonal tube and two inner cylindrical tubes

(today replacement on 20 % U(today replacement on 20 % U235 235 fuel isfuel is started) started)

The nominal thermal power is 10 MWThe nominal thermal power is 10 MW

Neutron flux in the core is about 10Neutron flux in the core is about 101414n/cmn/cm22ss

Ten Ten hhorizontal orizontal eexperimental xperimental channels (HEC)

The WWR-M KRR is a light water moderated and The WWR-M KRR is a light water moderated and cooled tank-type reactor with a beryllium cooled tank-type reactor with a beryllium reflectorreflector

The reactor currently uses 36 % enriched The reactor currently uses 36 % enriched uranium-235 WWR-M2 fuel assembliesuranium-235 WWR-M2 fuel assemblies, , each of which each of which consists of an outer hexagonal tube and two inner cylindrical tubesconsists of an outer hexagonal tube and two inner cylindrical tubes

(today replacement on 20 % U(today replacement on 20 % U235 235 fuel isfuel is started) started)

The nominal thermal power is 10 MWThe nominal thermal power is 10 MW

Neutron flux in the core is about 10Neutron flux in the core is about 101414n/cmn/cm22ss

Ten Ten hhorizontal orizontal eexperimental xperimental channels (HEC)

PPhysical basis of NFThysical basis of NFT

Through these minima the neutrons transmit & form rather narrow quasi-mono-chromatic filtered beams


The general idea of NFT is transmission of white spectrum through the thick layers of materials, which nuclei have the deep interference minima in their total neutron cross sections

10-1 100 101 102 103 104 1050,1

1

10

100

1000

2 keV

Tot

al c

ross

sec

tion,

b

Neutron energy, eV

25-Sc-45

Essential principle of NFBT


Inte

nsit

y of

neu

tron

s, r

el.u

n.

1.e-5 eV Neutron energy 20 MeV

1014 n/cm2s

Inte

nsit

y of

neu

tron

s, r

el.u

n.

Neutron energy 2 keV

105 - 108 n/cm2s

1 – reactor core, 2 – beryllium reflector; 3 – horizontal channel tube; 4 – beam shutter disks; 5 – preliminary collimator;

6 – filter-assembles; 7 – filter components; 8 – outside collimator.

1 – reactor core, 2 – beryllium reflector; 3 – horizontal channel tube; 4 – beam shutter disks; 5 – preliminary collimator;

6 – filter-assembles; 7 – filter components; 8 – outside collimator.

Reactor (white)

spectrumQuasi-mono-energy line

Merits & Demerits of NFTMerits & Demerits of NFT


Merits DemeritsNeutron line with energies from thermal to several hundred kilo-electron-volts

Presence of parasitic energy lines in filtered neutron spectrum

High intensity 105 – 108 n/cm2s

Gamma background

Quasi-mono-energy of neutron line(economy)Short reactor time to get high statistical accuracy

(economy)High price of high enriched isotopes

Neutron filter technique at research reactors allows to extract from white neutron reactor spectrum a neutron line with certain energy

IImprovement of filter puritymprovement of filter purity(ways of removing(ways of removing of parasitic energy lines)


1) To take so thick layer of the material that only neutrons, corresponding to the most deep interference minimum, would be able to pass through it

2) To use additional materials, for which resonance maxima in their total neutron cross sections coincide with interference minima for filter material, with the exception of the most deep interference minimum

Set of filter components in the NPDSet of filter components in the NPD


The wide set of natural elements and hThe wide set of natural elements and high-pure isotopes are used as components for are used as components for neutron filtersneutron filters

Natural elements: Si, Al, V, Sc, S, Mn, Fe, Ti, Mg, Co, Ce, Cr, Rh, Cu,B, Cd, LiF

HHigh-pure isotopes: isotopes:5252ССr (99.3%), r (99.3%), 5454Fe (99.92%),Fe (99.92%),5656Fe (99.5%), Fe (99.5%), 5757Fe (99.1%), Fe (99.1%), 5858Ni (99.3%), Ni (99.3%), 6060Ni (92.8– 99.8%), Ni (92.8– 99.8%), 6262Ni (98.0%), Ni (98.0%), 8080Se(99.2%), Se(99.2%), 1010B(85%), B(85%), 77Li (90%)Li (90%)

The wide set of natural elements and hThe wide set of natural elements and high-pure isotopes are used as components for are used as components for neutron filtersneutron filters

Natural elements: Si, Al, V, Sc, S, Mn, Fe, Ti, Mg, Co, Ce, Cr, Rh, Cu,B, Cd, LiF

HHigh-pure isotopes: isotopes:5252ССr (99.3%), r (99.3%), 5454Fe (99.92%),Fe (99.92%),5656Fe (99.5%), Fe (99.5%), 5757Fe (99.1%), Fe (99.1%), 5858Ni (99.3%), Ni (99.3%), 6060Ni (92.8– 99.8%), Ni (92.8– 99.8%), 6262Ni (98.0%), Ni (98.0%), 8080Se(99.2%), Se(99.2%), 1010B(85%), B(85%), 77Li (90%)Li (90%)

Set of FC in the NPDSet of FC in the NPD (cont.) (cont.)


The wide set of filter materials allows to modify The wide set of filter materials allows to modify filter parameters (purity, intensity, width, etc.) filter parameters (purity, intensity, width, etc.) subject to the given research tasksubject to the given research task Through expensiveness of high enriched Through expensiveness of high enriched isotopes, the natural elements or enriched isotopes, the natural elements or enriched isotopes available in NPD are usually considered isotopes available in NPD are usually considered as components ofas components of new new or or improved improved filtersfilters

New filter 7.5 keV (New filter 7.5 keV (existexist): main component Cu): main component Cu

New filter 275 keV (New filter 275 keV (developdevelop): main component Mn): main component Mn

The wide set of filter materials allows to modify The wide set of filter materials allows to modify filter parameters (purity, intensity, width, etc.) filter parameters (purity, intensity, width, etc.) subject to the given research tasksubject to the given research task Through expensiveness of high enriched Through expensiveness of high enriched isotopes, the natural elements or enriched isotopes, the natural elements or enriched isotopes available in NPD are usually considered isotopes available in NPD are usually considered as components ofas components of new new or or improved improved filtersfilters

New filter 7.5 keV (New filter 7.5 keV (existexist): main component Cu): main component Cu

New filter 275 keV (New filter 275 keV (developdevelop): main component Mn): main component Mn

7.5 keV 275

keV


Neutron filters used in NPDNeutron filters used in NPD

Components of some filtersComponents of some filters


22 ±0.7 ±0.7 keV filter keV filter ( (g/cmg/cm22))10B (85%) Sc 60Ni 54Fe S 59Co Al

0.2 104.6 80.2 39.35 56.0 26.7 0.54

24 24 ±0.96±0.96 keV filter keV filter ((g/cmg/cm22))10B (85%) S Fe Al

0.95 16.35 236.1 99.86

54 54 ±2±2 keV filter keV filter ((g/cmg/cm22))10B (85%) Si S Al

0.2 144.926 36.7 10.796

133 133 ±1.4±1.4 keV filter keV filter ((g/cmg/cm22))10B (85%) 52Cr 58Ni 60Ni Si Al

0.2 95.94 194.06 3.1157 93.08 0.54

Procedure of neutron filter Procedure of neutron filter creationcreation


1-th step: modeling calculation of neutron

filtered spectra using information from ENDF;

2-nd step: creation of filter with components

chosen by

calculation;3-rd step: experimental testing of the

created filter.

If it is necessary the sequence of these steps is repeated.


Fundamental investigationsFundamental investigations

High precision measurementsHigh precision measurements ((with accuracywith accuracy betterbetter 1%1%)) of total neutron cross sections, of total neutron cross sections, averagedaveraged on filter spectrum on filter spectrum

Measurements (Measurements (with accuracywith accuracy 3-6%3-6%)) of neutron of neutron scattering cross sectionsscattering cross sections, , averagedaveraged on filter on filter spectrumspectrum

Measurements (Measurements (with accuracywith accuracy 5-6% 5-6% )) of of activation cross sections, activation cross sections, averagedaveraged on filter on filter spectrumspectrum

To To determinedetermine averaged resonance averaged resonance parametersparameters To To estimateestimate self-shielding factor self-shielding factor

To To feelfeel resonance parameters of single resonance parameters of single resonanceresonance

High precision measurementsHigh precision measurements ((with accuracywith accuracy betterbetter 1%1%)) of total neutron cross sections, of total neutron cross sections, averagedaveraged on filter spectrum on filter spectrum

Measurements (Measurements (with accuracywith accuracy 3-6%3-6%)) of neutron of neutron scattering cross sectionsscattering cross sections, , averagedaveraged on filter on filter spectrumspectrum

Measurements (Measurements (with accuracywith accuracy 5-6% 5-6% )) of of activation cross sections, activation cross sections, averagedaveraged on filter on filter spectrumspectrum

To To determinedetermine averaged resonance averaged resonance parametersparameters To To estimateestimate self-shielding factor self-shielding factor

To To feelfeel resonance parameters of single resonance parameters of single resonanceresonance

Type of informatio

n


MMain systemsain systems of of experimentalexperimental equipmentequipment

((may be different in configuration and sizemay be different in configuration and size )

1) 1) System for forming of filtered neutron System for forming of filtered neutron beambeam

2) System of radiation shielding2) System of radiation shielding

3) Sample management system3) Sample management system

4) 4) NNeutron detector and counting systemeutron detector and counting system

1) 1) System for forming of filtered neutron System for forming of filtered neutron beambeam

2) System of radiation shielding2) System of radiation shielding

3) Sample management system3) Sample management system

4) 4) NNeutron detector and counting systemeutron detector and counting system

Forming system of filtered neutron beamForming system of filtered neutron beam


• Preliminary forming of beam - two iron and boron carbide collimators

• Further forming - in the 1-st three discs of shutter & in outer collimator (in the order lead, textolite and mixture of paraffin with H3BO3)

• The collimation system provides beam narrowing to necessary diameter

• The elements of neutron filtration system - in the 1-st three disks of shutter & in the outer collimator• To facilitate and quicken the procedure of filter changing, special steel containers for filters were made

• Preliminary forming of beam - two iron and boron carbide collimators

• Further forming - in the 1-st three discs of shutter & in outer collimator (in the order lead, textolite and mixture of paraffin with H3BO3)

• The collimation system provides beam narrowing to necessary diameter

• The elements of neutron filtration system - in the 1-st three disks of shutter & in the outer collimator• To facilitate and quicken the procedure of filter changing, special steel containers for filters were made

iincludesncludes the elements of beam collimation the elements of beam collimation & & neutron filtrationneutron filtration


NNeutron detector and counting eutron detector and counting systemsystem

neutron counter, electronic blocks, personal computer and communication lines about 50 m long between spectrometric installation and measuring room

En <= 12 keV - helium-3 counters (СНМ-37, LND 2527) En >= 12 keV - hydrogen recoil counters (CHM-38, LND 281)

En <= 12 keV - helium-3 counters (СНМ-37, LND 2527) En >= 12 keV - hydrogen recoil counters (CHM-38, LND 281)

NDfor σtot

NDfor σtot

NDfor σel

NDfor σel

Five assemblies of 7 He-3 counters СHМ‑17Set of 7 hydrogen counters LND‑281 Set of 7 helium counters LND‑2527

ND for dσ/dΩND for dσ/dΩ

58 helium-3 counters placed in five layers, located just above the sample

Some experimental resultsSome experimental results

1000 10000 1000004,2

4,3

4,4

4,5

4,6

4,7

4,8

4,9 #22217Kirilyuk,1987

Litvinsky,1985

ENDF libr.

Vertebnyi,1986

C-nat

OUR RESULTS #10395 Alexandrov,1997 #20420 Pham Zuy Hien,1992 #20302 #10935

Tot

al c

ross

sec

tion

, bar

n

Neutron energy, eVThe accuracy tottot is between 0.3% and 1.7%.The accuracy tottot is between 0.3% and 1.7%.

152.9 keV

Concerning BNL-325 isotope Concerning BNL-325 isotope 1313C, part of which in natural C, part of which in natural carbon makes only 1.1%, has strong p-resonance with carbon makes only 1.1%, has strong p-resonance with energyenergy

152.9 ±1.4152.9 ±1.4 keVkeV (J=2, (J=2, ГГn=3.7 ± 0.7 keVn=3.7 ± 0.7 keV, , ГГγ=4.0 ± γ=4.0 ± 1.6 keV)1.6 keV)



50000 55000 60000 65000 700001

10

100

CENDL-2

JEFF-3.0

BROND-2

JENDL-3.3

ENDF/B-6

Carlton, 2000 Spencer, 1972 Stieglitz, 1971 Our exp. result

Tot

al C

ross

Sec

tion

, ba

rn

Neutron Energy, eV

Some experimental results (cont.)Some experimental results (cont.)

In energy region from 50 keV to 60 keV isotope Cr-52 has 2 In energy region from 50 keV to 60 keV isotope Cr-52 has 2 resonances with energies ~ 50 keV and ~resonances with energies ~ 50 keV and ~ 58 58 keV.keV.

How can we get information about How can we get information about resonance resonance

parameters?parameters?

52Cr

New direction in NFBT New direction in NFBT (developing)(developing)


1) Set of of σσtottot, , averagedaveraged on filter spectra, the main on filter spectra, the main

energy of which are shiftedenergy of which are shifted

How can we get information about How can we get information about resonance parameters by NFBT?resonance parameters by NFBT?


New direction in NFBT New direction in NFBT (cont.)(cont.)

1) Shift of the main energy of filter owing toowing to dependencedependence energy of scattering neutrons from angle of energy of scattering neutrons from angle of scatteringscattering

0 20 40 60 80 100 120 140 160 18034

36

38

40

42

44

46

48

50

52

54

En

erg

y o

f sc

atte

rin

g n

eutr

on

s, k

eV

Angle of scattering, degree

Cu (63.546) Ni (58.69) Al (26.98) Mg (24.3) C (12.01) Be (9.012) Ti (47.867)

2

22

2

2

2/ sincos

m

M

mM

mEE

Filter Detector

Correcting sample Investigated sample

Filter

Detector

Filter Detector

Correcting sample Investigated sample

Filter

Detector

New direction in NFBT New direction in NFBT (cont.)(cont.)


2) Set of of the the averagedaveraged σtottot

using using filter filter the main the main energy energy line line of whichof whichis cutted is cutted into 2 or into 2 or 33 parts parts

How can we get information about resonance parameters How can we get information about resonance parameters by NFBT?by NFBT?

ConclusionConclusion1.1. NFBT at research reactors allows to get NFBT at research reactors allows to get

experimental data with experimental data with high accuracyhigh accuracy in in energy region energy region from thermal to several from thermal to several hudreed keVhudreed keV σσtottot < 1%; < 1%; σσelel <3-4%; <3-4%; ddσσelel/d/dΩ Ω <5-6%; <5-6%; σσn,n,γγ <5-6% <5-6%

2.2. New directions (shift & cutting main filter line) New directions (shift & cutting main filter line) will allow to get information aboutwill allow to get information about resonance resonance parameters parameters


to make progress in development to make progress in development ofof

nuclear simulation codesnuclear simulation codes generation of END librariesgeneration of END libraries

THE BASIS FOR ANY TRANSPORT CALCULATIONS for operating & future reactors for nuclear technologies in industry for nuclear technologies in medicine, etc.

Conference chairman: Ivan M. Vyshnevskyi (Director of KINR) Scientific secretary: Vitali Yu. Denisov (KINR)

E-mail: [email protected] Website: http://www.kinr.kiev.ua/NPAE-2010

Collective processes in atomic nuclei

Neutron and reactor physics, nuclear data

Nuclear reactions Problems of atomic energy

Nuclear structure and decay processes

Applied nuclear physics in medicine&industry

Rare nuclear processes Experimental facilities&detection techniques

TOPICS


Thank You

for your attention!

e-mail: [email protected]

precision neutron cross section measurements at reactor neutron filtered beams o. gritzay, v....

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