Assement of radionuclide concentration in various samples by gamma spectrometry and LSCJ. Berzins, D.Riekstina, O. Veveris

Institute of Solid State Physics University of Latvia

Dresden 2010

The Laboratory was organized as the group of the Laboratory of nuclear reactions in 1986 after the accident in Chernobil NPS with the aim to control via gamma spectrometry the environment and measure the radioactivity in foodstof and other samples. Since 1998 the group was reorganized to the Material radioactivity testing laboratory. The quality assurance system was implemented in our laboratory since the year 2000.

Different contaminate samples: soils, waters, metal scrap and various types of samples, irradiated in the research nuclear reactor, were measured by gamma spectrometer. The concentrations of radionuclide were determined using the high resolution HPGe gamma- spectrometer type Ortec within the energy range of 50- 2000 keV. For measuring of large radioactive waste volums in the metal barrel, gamma-spectrometer with NaJ detector were used. The uncertainty of measurements was within the range of 3-10%, but the minimal detectable activity 0.3 Bq/kg.

The measurements of high tritium activities in reactor basin and for monitoring contaminate groundwater were carried out with the liquid scintillation spectrometer Packard TRI-CARB using the scintillation liquid OptiPhase HiSafe3. The measurement time for H-3 didnt exceed some hours and uncertainty was less than 2%. The credibility of obtained results is ensured by the quality assurance and control. The main requisitions involved in the quality assurance of the laboratory according to the requirements of ISO/IEC 17025:2005 are: 1) the use of calibrated equipment only; 2) the regular long-time use of reference materials for the control of equipment; 3) the regular participation in the interlaboratory intercomparison exercises, organized by the RISO National Laboratory (Denmark) and IAEA (Vienna).

Measurements

Free release of reactor materialsMonitoring for potentially contaminated territoriesWater quality controlCustomer service J-131 from hospitals - metal scrap from foreign countries - samples from illegal radioactive material transport

HPGe gamma spectrometer

Efficiency of HPGe detectors

NaJ gamma spectrometer

Liquid scintilator spectrometer

iSOLO equipment for alfa and beta measurements

Methods

For the measurements we use 15 methods.The most importent are:Determination of the radionuclides concentration by high resolution gamma-ray spectrometry. T190-1-24-237-2004Water quality Determination of the activity concentration of radionuclides by high resolution gamma-ray spectrometry. LVS ISO 10703:2008.Water quality. Determination of the specific activity of tritium. Liquid scintilation counting method. LVA ISO 9698:2003. Building materials quality Determination of the radionuclides and specific activity of radionuclides in building materials by gamma-ray spectrometry. LVS ISO 257:2000.

Our internal quality audit program covers all requirements of ISO/IEC 17025:2005 standard, but the main attention is paid to the analysis of results of laboratorys participation in intercomparison measurements, their evaluation, interpretation and determination of uncertainty sources. Since 1999 laboratory is a regular participant in the interlaboratory intercomparison exercises organized by the RISO National Laboratory (Denmark) and IAEA (Vienna). Such nuclides as K-40, Mn-54, Co-57, Co-60, Zn-65, Cs-134, Cs-137, Eu-152, Ra-226, U-238 and Th-232 were analyzed in following intercomparison samples: soils, sediment, seaweed, aerosol, grass, hay, meat, dray milk, waters.

Quality assurance Quality System Quality control

Experienced staff Use of standard samples Premises, surroundings Measurement of background Validated methods Analysis in duplicates Calibrated equipment Control charts: background, standard peak stability Calibrated standards Reference materials Internal audit Staff training Participation in intercalibration

Participation of laboratory in the intercomparison exercises

YearOrganizerObjectRadionuclides1999Risoe National laboratory, DenmarkSediment, milk, meat, seaweed, hayK-40, Mn-54, Co-60, Cs-137, Ra-226, Th-2322000Risoe National laboratory, DenmarkMilk, aerosols, soil, seaweedK-40, Cs-137, Co-60, Mn-54, Ra-226, Th-2322002IAEA, ViennaMineral matrixMn-54, Co-57, Co-60, Cs-134, Cs-137, Eu-1522003Risoe National laboratory, Denmarkmilk, mineral matrix, seaweedCs-137, K-402004-2005Risoe National laboratory, DenmarkSediment, soil, seaweedK-40, , Cs-137, U-238, Th-2322006IAEA, ViennaSoil, grass, waterK-40, Mn-54, Co-60, Zn-65, Cs-134, Cs-137

Figure compares our results with the weighted mean in seaweed. There is a good agreement between them.

Column diagram of sum of z-scores for results from all radionuclides combined showing contributions from individual samples (No. 17-Laboratory of Radiation Physics).

137Cs content in mushrooms in Latvia (1987)

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* Shut-down medical facility DubultiBoring of samples

Pollution with Ra-226 depending on the depth in Dubulti

Ra_226 concentration in the waste from Dubulti (in barrels)

Chart1

215

608

1410

124

93

75

113

908

5450

130

182

251

191

173

170

129

104

95

394

845

264

426

672

146

633

1116

152

526

124

184

393

242

215

340

258

186

1032

1192

714

1027

453

621

201

709

845

836

112

134

164

370

458

903

D(nSv/h)

A(Bq/kg)

Sheet1

338215

7.6608

22801410

12124

38.293

28.475

51.6113

1010908

65005450

28.6130

75.4182

224251

31.2191

70173

33.8170

50129

20.4104

10095

290394

1366845

51264

694426

212672

66.8146

764633

9001116

238152

362526

1124

47.6184

34393

430242

40215

232340

298258

155186

5481032

3221192

1220714

17.41027

452453

202621

392201

174709

920845

646836

426112

3134

29.8164

378370

428458

468903

Sheet1

D(nSv/h)

A(Bq/kg)

Sheet2

Sheet3

Chart1

509151632

486131015

52514120

693421618

60121167

62118132

56615111

55213113

58415123

530161211

46114112

57619158

513211613

49313111

51716121

49614111

Concentration of radionuclides in soils (Salaspils)

K-40

Th-232

U-238

Cs-137

Sampling points

Bk/kg

Sheet1

K-40Th-232U-238Cs-137

509151632

486131015

52514120

693421618

60121167

62118132

56615111

55213113

58415123

530161211

46114112

57619158

513211613

49313111

51716121

49614111

54517137

Sheet1

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

Koncentration of radionuclides in soils (Salaspils)

K-40

Th-232

U-238

Cs-137

Sampling points

Bk/kg

Sheet2

Sheet3

Chart2

82654251

75858269

43458265

99362314

474442111

357442410

30938206

36678365

382331816

411352014

38736189

54359322

52049.916666666724.757.6666666667

K-40

Th-232

U-238

Cs-137

Sampling points

Bk/kg

Concentration of radionuclides in soils (Baldone)

Sheet1

82654251

75858269

43458265

99362314

474442111

357442410

30938206

36678365

382331816

411352014

38736189

54359322

52050258

Sheet1

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

K-40

Th-232

U-238

Cs-137

Paraugu noemanas punkti

Bk/kg

Radionukldu koncentrcija augsn (Baldone)

Sheet2

Sheet3

Results of tritium detection in Latvia:

Communal water sources 155 objects 5 Bq/L < T < 10 Bq/L0,01 Bq/l < < 0,2 Bq/l 0,1 Bq/l < < 0,6 Bq/l

Water for food industry 54 objects 5 Bq/L < T < 10 Bq/L 0,01 Bq/l < < 0,05 Bq/l 0,1 Bq/l < < 0,4 Bq/l

Chart1

1290210150

3.57427

4602119

1453.59.8

55911.8

3209351

Activity in building materials

Bq/kg

Chart2

1290210150

3.57427

4602119

1453.59.8

55911.8

3209351

K-40

Th-232

U-238

Bq/kg

Acivity concentration in building materials

Sheet1

Granite1290210150

Marble3.57427

Sand4602119

Dolomite1453.59.8

Line55911.8

Cement3209351

Sheet2

Sheet3

Conclusions

The use of gamma and beta spectrometry methods allow:establish the pollution level in the territories included in the monitoring decrease during the last years however unexpected changes was detected;identify and evaluate the wastes of various origin;control the quality of drinking water according to the Latvian Cabinet of Ministers regulations No.235, adopted in 2003, provision the entry in force of the EU Council Directive 98/83/EC.

Only credible and justified results can be the basis for further use in any field, thus making it possible to make legitimate decisions.

Thank you for your attentionThank you for your attention

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