Year
2007
Abstract
The Rokkasho Reprocessing Plant (RRP) represents the state-of-the-art for deployed international safeguards measurement systems. The focus of this paper is the Temporary Canister Verification System (TCVS), a passive neutron nondestructive assay (NDA) system developed collaboratively between Japan Nuclear Fuel Limited (JNFL), the International Atomic Energy Agency (IAEA), the Japanese Safeguards office (JSGO) and Los Alamos National Laboratory (LANL). The TCVS assays a Temporary Canister (TC) containing mixed uranium-plutonium oxide (MOX) powder. There are two TCVS systems (line “A” and line “B”); both were installed in May 2006. A californium-252 (252Cf) calibration was conducted in June 2006, and active MOX commissioning was completed in December 2006. Both the mechanical and physics design of TCVS presented significant challenges. The mechanical design required integration of the TCVS into an existing glove box line, around numerous restrictions and obstacles. The physics design not only had to accommodate the limitations imposed by the existing glove box, but also had to address an unusual counting dead-time situation where increasing sample mass is not correlated to increasing dead time in each individual neutron detector. Additionally, the calibration had to accommodate TCs with various fill heights, in the region of changing counting efficiency. This paper briefly summarizes the Monte Carlo system design, reviews the installation and calibration effort, summarizes the active calibration results and presents the dead-time methodology.