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Liquid Scintillation Counting as multi-nuclide screening method Evgeny Taskaev.

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Presentation on theme: "Liquid Scintillation Counting as multi-nuclide screening method Evgeny Taskaev."— Presentation transcript:

1 Liquid Scintillation Counting as multi-nuclide screening method Evgeny Taskaev

2 Common approach – gross alpha/beta, gamma spectrometry: - Low counting efficiency Screening for technogenic and natural radionuclides - Radiochemical separation can be involved - High MDA 90-Sr - Limited knowledge on isotopic composition, including most toxic nuclides like 3-H, 90-Sr, Isotopes of Ra and Transuranics

3 Screening for technogenic and natural radionuclides ~ 100%, - Counting efficiencyfor  ~ 100%, ~ 100% for beta (> 100 кeV) ~ 100% Liquid scintillation counting: - Possibility to estimate energy with resolution ~10 %- 5% ( кэВ) when using ~10 % for alpha emitters and - 5% ( кэВ) when using PERALS  system - Low MDA - Low MDA ~ mBq for beta and 5 mBq for alpha emitters (10 h counting with TRI-CARB 2550) c/s - Low background – c/s - Comparatively short time for sample preparation and counting less than 3 кeV - Threshold for beta counting – less than 3 кeV

4 Liquid scintillation counting Spectra are complicated, peaks are not resolved Counting efficiency depends on chemical composition of the sample

5 Scientific-Industrial Association “Radon”, Moscow, Russia S. Malinovsky, A. Ermakov, I. Kashirin, et all. Poland

6 SpectraDecBeta SpectraDec(Beta) – software package for processing β and mixed α / β spectra from LS counters Software allows to determine activity of individual nuclides in a sample with several nuclides with overlapping spectra Easy to use with minimal participation of operator Modular structure makes software flexible for integration into another software and to addition of another modules if needed Mathematical modeling of real spectrum. Spectral data from counting of individual nuclides presented in sample are used to model real spectrum

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8 Identification of radionuclides through modeling complex spectra Identification of radionuclides through modeling complex spectra using individual spectra data from nuclide library H3H 14 C 137 Cs 241 Am 90 Sr+ 90 Y

9 Creating nuclide library Addition of radionuclide to the library Counting Mathematical «purification» of spectra Transformation of spectra to software format Radiochemical separation Reference source Preparation of quench set Counting

10 Initial spectrum Transformed spectrum Ra-226 and its progeny Initial spectrum is transformed into groups For counters with linear ADC (TriCarb) – a quasi-arithmetic progression is used For counters with linear ADC (TriCarb) – a quasi-arithmetic progression is used For counters with logarithmic ADC (Guardian) – linear combination For counters with logarithmic ADC (Guardian) – linear combination

11 Pb-210 Po-210 Bi-210 Ra-226 Individual spectra of 226 Ra and its decay products

12 Guardian 1440 Guardian 1440 Logarithmic ADC Set of quenched samples after transformation Tri-Carb 2550 Tri-Carb 2550 Linear ADC

13 90 Sr 85 Sr Volume, L NuclideActivity,Bq/sampleActivity, Bq/m 3 Error ± % 8 89 Sr ≤ ≤ 1.8e Sr e-3 6.6e-329 Determination of Sr-90 in water Sr-90 with Sr-85 tracer

14 85 Sr 90 Sr 90 Y 85 Sr 90 Sr 90 Y Determination of Sr-90 in soil using Sr-85 tracer A 85 Sr = 0.42 Bq in each sample, m soil = 10 g A 90 Sr = 245 ± 90 Bq/kg A 90 Sr = 5.2 ± 2.2 Bq/kg

15 Activity,Bq/sampleError, ± % 89 Sr Sr Sr-90 in particulate filter

16 NIST-NEI Pu Bq/g Pu Bq/g Am Bq/g Cm Bq/g Pu-241 Pu-239 Am-241 Cm-244 Blind sample spectrum send by Analytics

17 H-3, Fe-55, Ni-63 G r o u p s C o u n t s H-3 Fe-55 Ni-63 NIST-NEI Blind sample spectrum send by Analytics

18 H-3, Tc-99 and Cs-137

19 Blind sample spectrum send by Analytics

20 H-3, Tc-99 and Cs-137 Blind sample spectrum send by Analytics

21 H Tc Cs G r o u p s C o u n t s H-3 Tc-99 Cs-137 Blind sample spectrum send by Analytics Activity, Bq added found

22 Conclusion SpectraDecBeta SpectraDec(Beta) Enhances LSC capabilities for determination of individual nuclides in complex mixtures Allows to simplify sample prep procedures for many nuclides Combined with simple radiochemical separation and extractive cocktails makes LSC method excellent tool for screening

23 Thank you for your attention


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