Year
1996
Abstract
Non-destructive assay systems for the verification of nuclear materials in input dissolver solutions and Pu product solutions of a spent fuel reprocessing plant have been developed at the Tokai Reprocessing Plant (TRP) since 1991. Taking into account every possible way for authentication, the instruments were equipped with some devices. As an example, an extra computer system with some electronics modules to be used under inspector control was installed in parallel with operator’s one for the independent inspection by national/ international safeguards inspectors. We also added suitable U/Pu reference materials for measurement control of the instruments. As the results of an acceptance test, which was held in 1995 in the presence of inspectors, we confirmed that the “precision for determining uranium and plutonium concentrations of a typical spent fuel dissolver solution (approx. 177gU/L, 1.7gPu/L) was around 0.19’0 RSD and 0.6% RSD, respectively, for 1000-s counting. Whereas, the precision for plutonium in product solutions was confirmed to be around 0.5’%0RSD for 800 sec. Furthermore, the measurement results by this method and by the conventional Isotope Dilution Mass Spectrometry (IDMS) were in good agreement in performance tests. Consequently, it was found that both the instruments would be sufficient y avaiIable to the safeguards inspections at the TRP.