NEUTRON EMISSION RATE MEASURING METHOD AND MEASURING EVALUATION PROGRAM OF IRRADIATED FUEL ASSEMBLY

摘要

PROBLEM TO BE SOLVED: To provide a neutron emission rate measuring method capable of measuring extremely efficiently the neutron emission rate from an irradiated (spent) fuel without requiring disassembly of an irradiated fuel assembly, and enabling the irradiated (spent) fuel to be stored in a very expensive cask efficiently without excessive allowance. SOLUTION: In this emission rate measuring method of neutrons emitted from a neutron emission nuclide generated inside the fuel assembly irradiated with neutrons in a reactor, a response factor Wijdefined as a neutron flux fijformed at the position j of a neutron detector arranged on the side of the fuel assembly based on neutrons generated in a fuel rod i on a certain position constituting the fuel assembly, namely, the neutron source intensity Ni. Then, the neutron emission rate Sas of the fuel assembly is determined from the ratioϕj/Σ[Si×Wij] of the neutron fluxϕjdetected by the neutron detector arranged on the outside position j of the fuel assembly to the sumΣ[Si×Wij] of all the fuel rods of the product of an assumed neutron source intensity Siand the response factor Wijof the fuel rod i based on a neutron source intensity distribution in the fuel assembly. COPYRIGHT: (C)2006,JPO&NCIPI