Year
1990
Abstract
A new class of nondestructive assay (NDA) systems has been installed in the automated mixed-oxide fabrication facility operated by the Power Reactor and Nuclear Fuel Development Corporation in Japan. The systems are based on a high-level neutron coincidence counting technique, accommodate robotic sample operation, and can be used in a continuous, unattended mode for periods up to 1 month. The systems are in routine use to determine the plutonium inventory and the flow of plutonium into and out of the facility for safeguards purposes. This is achieved by the Plutonium Canister Assay System for mixed-oxide powder, Material Accountancy Glove-Box Counter for process materials, Fuel-Pin Assay System for pins, and the Fuel Assembly/Capsule Assay System for assemblies. The International Atomic Energy Agency and the Japan Nuclear Safety Bureau obtain inspection data without the need for an inspector at the facility at the time of the measurement. Authentication measures for the detector heads and the data collection systems are applied to assure that the systems perform as specified and as agreed on between the inspectorates and the operator. The results of periodic measurement of sealed neutron sources (252Cf), placed in the detectors to check the response of the NDA system is presented. The excellent performance of the NDA systems data related to reliability, precision, and stability is discussed. The application of the data for on-site material balance evaluation is demonstrated.