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
Outline 1 2 3 4 5 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
Why H-3? In 2009,CCRI(II)-K2.H-3 Samples: Tritiated water (3H-LNHB-11-07 n 10) Methods: TDCR (NIM-TDCR system) CIEMAT/NIST (no suitable tracer, H-3 or Mn-54 ) In 2011-2012,We measured H-3 again Samples: Tritium-labeled n-hexadecane Methods: TDCR (NIM-TDCR system) CIEMAT/NIST using Mn-54 as an external tracer
Outline 1 2 3 4 5 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
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
Outline 1 2 3 4 5 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
The procedure of the CIEMAT/NIST Method Tracer: 54 Mn Radionuclide to be analyzed: 3 H
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
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
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)
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!
Third Step: Sample Counting Detector: PerkinElmer Tri-Carb 3100TR 2 LS spectrometers Quench indicating parameter : tsie, range from 322-494 ( 54 Mn), range from 382-493 ( 3 H) 5 cycles of 20 minutes per source 10 6 counts in most quenched source
The CIEMAT/NIST results 0.44 0.42 The C/N results Reference time: 2012-04-20 00:00:00 (UTC) 0.40 H3-0.36 No tsie 0.38 0.34 0.32 0.30 300 320 340 360 380 400 420 440 460 480 500 520 tsie The quench correction curve of tritium Effciency (H-3) Count/ min -1 Mass (mg) Activity (Bq/g) H-B --- --- 15 --- --- H0 493.2 0.4266 173281 90.59 74730.4 H1 474.2 0.4172 148459 79.17 74908.2 H2 454.8 0.4070 151277 82.76 74860.6 H3 438.7 0.3980 185144 103.5 74906.9 H4 424.0 0.3894 128491 73.45 74869.5 H5 413.3 0.3830 123522 71.79 74879.2 H6 393.2 0.3699 146844 88.78 74535.5 H7 383.1 0.3637 102381 62.77 74752.9 H8 372.6 0.3566 89397 55.96 74666.5 RSD=0.17%
Outline 1 2 3 4 5 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
The procedure of TDCR Method
NIM TDCR System Measurement Chamber
The diagram of NIM-TDCR system
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
Activity(Bq/g) the optimum KB value Fiting line: The method of least squares Reference time: 2011-12-11 02:00:00 (UTC) 78,500 78,000 77,500 77,000 76,500 76,000 75,500 75,000 0.007 0.008 0.009 0.010 0.011 0.012 0.013 0.014 0.015 KB Intercept Slope 0.007 72478.6 3809.6 0.008 73453.3 3001.0 0.009 74401.7 2147.8 0.01 75256.8 1428.9 0.011 76061.5 747.6 74,500 0.012 76836.6 76.2 74,000 0.013 77568.8-598.0 73,500 0.014 78261.1-1207.2 0.30 0.35 0.40 0.45 0.50 TDCR 0.015 78946.8-1873.0
Acticity Concentration (kbq/g) The results of two methods 78.0 Reference time: 2012-04-20 00:00:00 (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
Outline 1 2 3 4 5 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
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 --- 0.65% Square root of the sum of quadratic components 0.99% 0.66%
Outline 1 2 3 4 5 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
The NIM s result of international comparison of activity measurements of tritiated water Uncertainty: 1.38% (k=2)
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