-
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)
-
*
-
* 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
**