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

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

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

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

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

6. Easy to use with minimal participation of operator
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
Mathematical modeling of real spectrum. Spectral data from counting of individual nuclides presented in sample are used to model real spectrum
Modular structure makes software flexible for integration into another software and to addition of another modules if needed
Easy to use with minimal participation of operator

8. Identification of radionuclides through modeling complex spectra using individual spectra data from nuclide library 3H
14C
137Cs
241Am
90Sr+90Y 4.
3.6
3.2
2.8
2.4 2.
1.6
1.2
0.8
0.4 0. 10 20 30 40 50 60 70 80 90

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

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

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

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

13. Determination of Sr-90 in water Sr-90 with Sr-85 tracer
Volume, L
Nuclide
Activity,
Bq/sample
Bq/m3
Error ± % 8
89Sr
≤ 0.006
≤ 1.8e-3 -
90Sr
0.021
6.6e-3 29

14. A90Sr = 245 ± 90 Bq/kg A85Sr = 0.42 Bq in each sample, m soil = 10 g
Determination of Sr-90 in soil using Sr-85 tracer
85Sr
90Sr
90Y
85Sr
90Sr
90Y
A90Sr = 245 ± 90 Bq/kg
A90Sr = 5.2 ± 2.2 Bq/kg
A85Sr = 0.42 Bq in each sample, m soil = 10 g

15. Sr-90 in particulate filter
Activity,
Bq/sample
Error,
± %
89Sr
1.83 3
90Sr
0.16 11

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

17. Blind sample spectrum send by Analytics
H-3
NIST-NEI
1743-7
Fe-55
C o u n t s
Ni-63
H-3, Fe-55, Ni-63
G r o u p s

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

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

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

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

22. Conclusion 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