PWR loss-of-coolant accident analysis capability of the WRAP-EM system

The modular computational system known as the Water Reactor Analysis Package (WRAP) has been extended to provide the computational tools required to perform a complete analysis of loss-of-coolant accidents (LOCAs) in pressurized water reactors (PWR). The new system is known as the WRAP-EM (Evaluation Model) system and will be used by NRC to interpret and evaluate reactor vendor EM methods and computed results. The system for PWR-EM analysis is comprised of several computer codes which have been developed to analyze a particular phase of a LOCA. These codes include GAPCON for calculation of initial fuel conditions, WRAP (the previously developd SRL analog of RELAP4/MOD5) for analysis of the system blowdown and refill, the FLOOD option in WRAP for analysis of the reflood phase, and FRAP for the calculation of the behavior of the hot fuel pin. In addition, a PWR steady-state initialization procedure has been developed to provide the initial operating state of the reactor system. The PWR-EM system is operational and is being evaluated to determine the adequacy and consistency of the physical models employed for EM analysis.