Year
1996
Abstract
A technique has been developed for verification of lightwater reactor operating history from measurements of irradiated fuel assemblies. The Fork detector is used to measure neutron and gross gamma-ray emissions from fuel assemblies. The measurements can be performed a few days after discharge or up to several years later. The neutron and gamma-ray ratios are used to check the consistency of the declared number of irradiated cycles for the assembly in the core. Reactor burnup calculation codes are used to correct the measured neutron rates for different initial enrichments and discontinuous irradiation histories. We have modified the Fork detector so that it can operate in the intense gamma-ray field emitted from freshly discharged fuel. This modification makes it possible to perform fuel verification during the annual fuel-reload and maintenance period.