Year
2015
Abstract
PyRorocess Integrated inactive DEmonstration Facility (PRIDE) is an engineering-scale facility for development of pyroprocessing technology using depleted uranium. As well as development of pyroprocessing technology, PRIDE is useful for test of nuclear material accounting devices because of a large capacity of 10 MTHM/year, and integrated process flow. In this point of view, a Unified Non-Destructive Assay (UNDA) was developed as a nuclear material accounting system for the PRIDE facility. The UNDA consists of 3 NDA techniques, i.e., total neutron counting with He-3 tubes for 238U mass measurement, a gamma spectroscopy for 235U enrichment measurement, and a mass balance for total U mass measurement. In this paper, the experimental results and performance of the total neutron counting and gamma spectroscopic modules was reported. DU pellets and 5 stainless steel (SUS304) containers having 10 kgU pellets per container were prepared, and a calibration curve was obtained within 10 to 50 kgU range. After powderization of DU pellets, another calibration curve for powder was obtained. It is expected that the number of total neutron counts with DU pellets is higher than powder because higher density of pellets result in higher neutron multiplication than powder with lower density. 2 calibration curves can be utilized in different physical conditions. After calibration of the PRIDE UNDA system, porous pellets were measured and the mass of 238U was determined. The gamma spectroscopic module, a NaI detector having a lead collimator hole with 4 cm diameter, was calibrated with 5 standard calibration sources (U3O8 powder having different enrichments), and U enrichment was measured with DU pellet and powder. Cylinder-shaped pellets cause an error higher than powder due to the vacancy between pellets within the collimator. It was recalibrated with MCNP simulation.