Quality control and uncertainty of measurement in ultra-trace analysis of nuclear materials; For high reliability of the safeguards environmental sample analysis

Usuda, Shigekazu; Magara, Masaaki  ; Esaka, Fumitaka  ; Sakurai, Satoshi ; Lee, C. G.; Yasuda, Kenichiro   ; Kokubu, Yoko   ; Suzuki, Daisuke   ; Shinohara, Nobuo ; Murata, Fujio*

JAEA (Japan Atomic Energy Agency) has been conducting the environmental sample analysis, which is one of the IAEA's safeguards measures. In the analysis, isotope ratios of ultra-trace amounts of nuclear materials (uranium and plutonium) in the samples taken from nuclear facilities are determined to detect "environmental signature" of undeclared nuclear materials and activities. In order to enhance the reliability of the measurement results, validation of analytical methods and estimation of uncertainty of measurement in such ultra-trace analysis are required at the level of worldwide standardization. In this presentation, the authors introduce the current activities and future perspectives of achievement of QA/QC (quality assurance and quality control) and the estimation of uncertainty as a member of the IAEA Network Analytical Laboratories for the environmental samples.