Standardization of Tritium by CIEMAT/NIST Method and TDCR Method

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1 Standardization of Tritium by CIEMAT/NIST Method and TDCR Method Wu Yongle 1,3 ; Liu Haoran 1,2 ; Liang Juncheng 2 ; Liu Jiacheng 2 ; Yue Huiguo 3 ; Liu Senlin 1 ; Yang Yuandi 2 ; Yuan Daqing 1 ; 1.China Institute of Atomic Energy(CIAE), Beijing, China 2.National Institute of Metrology(NIM), Beijing, China 3.Nuclear and Radiation Safety Center(NRSC), Beijing, China

2 Outline Introduction Samples Preparation Standardization of 3 H by CIEMAT/NIST Method Standardization of 3 H by TDCR Method Uncertainty Budget 6 International comparison of tritiated water

3 Why H-3? In 2009,CCRI(II)-K2.H-3 Samples: Tritiated water (3H-LNHB n 10) Methods: TDCR (NIM-TDCR system) CIEMAT/NIST (no suitable tracer, H-3 or Mn-54 ) In ,We measured H-3 again Samples: Tritium-labeled n-hexadecane Methods: TDCR (NIM-TDCR system) CIEMAT/NIST using Mn-54 as an external tracer

4 Outline Introduction Samples Preparation Standardization of 3 H by CIEMAT/NIST Method Standardization of 3 H by TDCR Method Uncertainty Budget 6 International comparison of tritiated water

5 Preparation of LS Samples Tritium(for CIEMAT/NIST and TDCR) 9 tritium samples and 1 matched background sample Container: 20 ml low potassium glass vials Sample composition : 15 ml Ultima Gold LLT Scintillator + 1 ml water + drops of 10% nitromethane in ethanol (quenching agent ) + Tritium-labeled C 16 H 34 (active solution ),typcal mass: 20mg Manganese-54 (only for CIEMAT/NIST) A set of 54 Mn samples were prepared in the same way

6 Outline Introduction Samples Preparation Standardization of 3 H by CIEMAT/NIST Method Standardization of 3 H by TDCR Method Uncertainty Budget 6 International comparison of tritiated water

7 The procedure of the CIEMAT/NIST Method Tracer: 54 Mn Radionuclide to be analyzed: 3 H

8 First step: Check the impurities of 54 Mn(tracer) active solution 54 Mn 60 Co Impurity: 60 Co Natural background: 40 K, 214 Bi, 228 Ac 228 Ac 214 Bi 40 K 228 Ac 214 Bi 54 Mn Point source Gamma-ray spectrometry

9 Impurity impact The impact of the impurity was taken into account both in calculations and experiments! For tracer To consider the contribution of the impurity, the total efficiency of the tracer is computed by the following formula: A + Mn-54 Co-60 total Mn-54 Co-60 AMn -54 ACo -60 AMn -54 ACo -60 A A:Activity

10 Second step: Theoretical calculations for C/N Computation of the energy spectrum Nuclear and atomic data Computation of Ionization quenching function (1) The ionization quenching parameter:kb=0.075(default) (2) The stopping power values(default) (3) Scintillator composition, density (modify to UG LLT)

11 Code Selection for C/N Theoretical calculations 54 Mn Decay type : EC-gamma decay Code: EMILIA (by A. Grau Carles) Atomic rearrangement model: KL 1 L 2 L 3 M 60 Co Decay type : Bata-gamma decay Code: CN2003(by E. Günther) Atomic rearrangement model: KLM 3 H Decay type : Pure Bata deacy Code: CN2003(by E. Günther) Thanks for codes authors excellent works!

range from 322-494 ( 54 Mn), range from 382-493 ( 3 H) 5

12 Third Step: Sample Counting Detector: PerkinElmer Tri-Carb 3100TR 2 LS spectrometers Quench indicating parameter : tsie, range from ( 54 Mn), range from ( 3 H) 5 cycles of 20 minutes per source 10 6 counts in most quenched source

13 The CIEMAT/NIST results The C/N results Reference time: :00:00 (UTC) 0.40 H No tsie tsie The quench correction curve of tritium Effciency (H-3) Count/ min -1 Mass (mg) Activity (Bq/g) H-B H H H H H H H H H RSD=0.17%

14 Outline Introduction Samples Preparation Standardization of 3 H by CIEMAT/NIST Method Standardization of 3 H by TDCR Method Uncertainty Budget 6 International comparison of tritiated water

15 The procedure of TDCR Method

16 NIM TDCR System Measurement Chamber

17 The diagram of NIM-TDCR system

18 Code selection TDCR code TDCR-07 code (by Philippe Cassette) The asymmetry of three PMTs was taken into account in our calculations Thanks for code author s contribution! Sample counting 10 6 counts in each of 3 doubles channels Experiment efficiency varied by grey filters

19 Activity(Bq/g) the optimum KB value Fiting line: The method of least squares Reference time: :00:00 (UTC) 78,500 78,000 77,500 77,000 76,500 76,000 75,500 75, KB Intercept Slope , , , TDCR

20 Acticity Concentration (kbq/g) The results of two methods 78.0 Reference time: :00:00 (UTC) 76.0 (75.37±0.75) kbq/g (74.79±0.52) kbq/g 74.0 Discrepance: 0.78% 72.0 C/N TDCR

21 Outline Introduction Samples Preparation Standardization of 3 H by CIEMAT/NIST Method Standardization of 3 H by TDCR Method Uncertainty Budget 6 International comparison of tritiated water

22 Uncertainty Budget Componient C/N TDCR Counting statistics 0.11% 0.1% Weighting 0.05% 0.05% Dead time 0.10% 0.06% Background 0.02% 0.03% Half-life <0.001% <0.001% Quenching indicator(tsie) <0.001% --- Decay data and model 0.31% --- CN:Tracer( 54 Mn) 0.92% --- TDCR:Efficiency calculation % Square root of the sum of quadratic components 0.99% 0.66%

23 Outline Introduction Samples Preparation Standardization of 3 H by CIEMAT/NIST Method Standardization of 3 H by TDCR Method Uncertainty Budget 6 International comparison of tritiated water

24 The NIM s result of international comparison of activity measurements of tritiated water Uncertainty: 1.38% (k=2)

25 Thank you for your attention!

Activity measurement of 55 Fe within the scope of the BIPM comparison 2006

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