Calculation of MUF for the Pyro-processing Facility

The IAEA safeguards system is divided into DIQ (Design Information Questionnaire), nuclear material accountancy, and additional measure such as C/S (Containment and Surveillance). As the detailed requirements for judging the diversion of nuclear materials, the IAEA suggests SQ (Significant Quantity) about SNM (Special Nuclear Materials), such as U and Pu, and the timeliness goal of detection about the diversion of nuclear materials. To operate facilities, it is required to accomplish these goals. In particular, in the case of the treatment facilities of spent nuclear fuel that has a high Pu content, it is very important to meet the requirements to judge the diversion of nuclear materials. However, given that item counting is impossible in bulk facilities, MUF (Material Unaccounted For) occurs inevitably in the process of nuclear material accountancy. Therefore, to meet the requirements, it is necessary to make evaluation in advance. To reduce such a MUF, the effects on a total MUF were analyzed. As a result, the error arising in a particular process such as U/TRU ingot and Porous Pellets was significant. Therefore, it is necessary to reduce measurement error in the process. MUF is one of requirements to judge the diversion of nuclear materials, and the requirement should be met. Nevertheless, it is required to come up with additional measures to prevent the exclusive use and reduce MUF, such as containment, surveillance, or multi-channel based processing design