PWR Plant Model to Assess Performance of Accident Tolerant Fuel in Anticipated Transients and Accidents

A PWR plant model based on the reactor system code TRACE has been assembled to enable the simulation of a broad spectrum of anticipated operational occurrences (AOO) and design basis accidents (DBA). The objective is to provide a simulation platform to support the development of advanced fuels and claddings and the deployment of accident tolerant fuel (ATF) in current PWR designs. The TRACE model simulates a Westinghouse 2308-MWt three-loop PWR, including standard primary and secondary loop components and various trips and control systems to model plant responses. Kinetics parameters for the standard UO2 fuel and nitride fuel (UN-U3Si2-UB4) have been developed from PARCS stand-alone full-core calculations to provide inputs to the TRACE point-kinetics model. Several transients have been analyzed to assess the performance of ATF relative to standard Zircaloy-clad UO2 fuel. These include complete loss of primary flow, steam generator tube rupture, small break (SB) and large break (LB) loss-of-coolant-accidents (LOCA). Among the accidents analyzed, the largest performance difference between the oxide fuel and the nitride fuel is in the LBLOCA where the peak clad temperature (PCT) for the nitride fuel is 30 K lower than that of the oxide fuel.