Assessment of the analysis capability for core-wide PWR pellet-clad interaction screening of Watts Bar Unit 1

Abstract

This article demonstrates the application of the Virtual Environment for Reactor Applications simulation environment to screen for pellet-clad interaction amongst the core-wide fuel rods within a pressurized water reactor, with emphasis on the multi-dimensional analysis capabilities of the BISON fuel performance code. The VERA codes utilized in this effort include the BISON fuel performance code and the VERA sub-element, which combines the MPACT neutron transport code and the COBRA-TF thermal-hydraulics code. This effort has involved screening Cycles 6 and 7 of Watts Bar Unit 1, which were selected on the basis that pellet-clad interaction failures had occurred during reactor start up in both cycles, despite the moderate power levels. These failure instances at Watts Bar Unit 1 offered an interesting test of the code’s veracity and a particularly challenging condition for this assessment.