The modular computational system known as the Water Reactor Analysis Package (WRAP) has; been extended to provide the computational tools required to p~rform a complet~ analysis of loss-ofcoolant 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

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... developed to analyze a particular phase of a LOCA. These codes include GAPCON for calculation of initial fuel conditions, WRAP (the previously developed SRL analog of RELAP4/MODS) 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 model.s employed for EM analysis.