Simulation study on non-destructive assay for fuel debris by using Fast Neutron Direct Interrogation (FNDI) method

摘要

An accounting method for nuclear materials in fuel debris in the Fukushima Daiichi nuclear power plant has not been decided. In Japan Atomic Energy Agency (JAEA), a project for nondestructive assay for the fuel debris by using Fast Neutron Direct Interrogation (FNDI) method has been started. The FNDI method which measures total amounts of fissile materials is expected to be a promising Non-Destructive Assay (NDA) technique. In this presentation, we report on a design study of the non-destructive measurement system and an applicability study for the cases in which various matrix materials are contained in a canister. The design study is conducted using a Monte Carlo Code PHITS and a four dimensional (4-D) visualization tool for neutron flux we have newly developed. In the applicability study conducted using a Monte Carlo Code MVP, results show that the FNDI method has possibility of being applicable to debris.