[en] The WRAP-EM system is a complete computational system for analysis of loss-of-coolant accidents (LOCAs) in light water power reactors. The system has been developed for use by the Nuclear Regulatory Commission in evaluating and interpreting reactor vendor evaluation model methods and results. the initial WRAP system was developed at the Savannah River Laboratory (SRL) in 1977. WRAP is a modified version of the RELAP4/MOD5 code with a modular structure, JOSHUA input templated records, automatic steady-state initialization procedure, and dynamic dimensioning capabilities. During 1978, the WRAP system was extended to provide a complete evaluation model (EM) capability for boiling water reactors (BWRs). The BWR-EM system has been extensively evaluated and is currently being verified by comparison with LOCA experiments and with vendor EM calculations. A similar capability for pressurized water reactors (PWRs) has been completed recently