Radionuclide distribution in irradiated BWR tie plate

Abstract

The contents and distribution of radionuclides in activated metallic wastes are major concerns while designing a leaching model in a safety case. This study investigated 60Co as a typical activation product in the lower tie plate (i.e., stainless steel endpiece of BWR fuel assembly) irradiated for 35.0 GWd/tHM burnup, using the imaging plate (IP) method. The activation calculations coupled with the Monte Carlo burnup and neutron transport calculation code (MCNP-BURN2) were also performed based on the burnup and operation conditions. The Co impurity content in the irradiated tie plate was obtained and used as an input to MCNP-BURN2. The IP method results showed that the intensity of photostimulated luminescence decreased with increasing distance from the top (near fuels) to bottom. This trend was consistent with that exhibited by MCNP-BURN2.Therefore, the simulations allowed us to model the three-dimensional radionuclide distribution within the tie plate.Graphical abstractDistribution of 60Co in the irradiated lower tie plate. Left shows the vertical distribution comparing the measurements and the MCNP-BURN2 results. Right represents the 3D model of 60Co distribution in the lower tie plate.