Feasibility study of direct plutonium mass measurement in high-concentrated plutonium solution by a new NDA; Advanced Solution Measurement and Monitoring System (ASMS)

Nakamura, Hironobu ; Takaya, Akikazu; Mukai, Yasunobu ; Hosoma, Takashi   ; Yoshimoto, Katsunobu; Tamura, Takayuki*; Iwamoto, Tomonori*

JNFL and JAEA have collaboratively started to develop an ASMS for RRP since 2007. The purpose of the development is to establish direct plutonium mass measurement technique by NDA of high concentrated pure plutonium nitrate solution in a strategic process tank. If it is established, ASMS provides direct Pu mass measurement and monitoring capability, substitutes for sampling and destructive analysis at IIV, and extends process monitoring to safety purposes. The target of the measurement uncertainty is set less than 6%(1) which is equivalent to the detection level of partial defect at IIV by NDA. The principle is similar to the one of NDA for MOX powder, but extended such as introducing variable alpha depends on solution properties. As a first trial, a simple prototype system was constructed and tested at PCDF. Two detectors with a gap were installed just center of the annular tank, then we carried out calibration using plutonium nitrate solution (-52kgPu). Consequently, good consistency between MCNP calculation and measured singles/doubles count rate were obtained. As a feasibility study, it was necessary to find out subjects to be solved. We would like to present benefits of ASMS, review installation and detector setup and summarize preliminary calibration results.