RETRAN-02 MOD5 and RETRAN-03 code benchmarks for Beaver Valley plant transients and FSAR analyses

Abstract-A RETRAN-02 MODS model and a RETRAN-03 model for the Beaver Valley Unit I plant were developed from an existing, but untested RETRAN deck. This study uses FSAR transient analyses, actual plant event data, and similar plant analyses performed with RETRAN and TRAC-BFl MODI to benchmark the RETRAN-2 MODS and RETRAN-3 plant model. Eight transients were chosen to qualify the RETRAN models: (I) a standard reactor trip, (2) a loss of one reactor coolant pump, (3) a loss of all reactor .coolant pumps, (4) an inadvertent opening of a pressurizer relief valve, (5) a loss of normal feedwater with auxiliary feedwater available, (6) a turbine trip, (7) a main steam line isolation valve closure, and (8) a main steam line break. These design basis transients were each chosen to isolate specific phenomena or plant design aspects of the RETRAN models that are exhibited in depressurization events, over-pressurization and over-temperature transients, and over-cooling accidents. Both the RETRAN-02 MODS and RETRAN-03 Beaver Valley models were successfully benchmarked. The RETRAN results compared well with the FSAR LOFTRAN analyses, an actual Beaver Valley single pump trip event, and Ringhals 2 and 4 analyses. The RETRAN-03 model performed well and provided a better best-estimate of plant phenomena than the RETRAN-02 MODS results; moreover, both the RETRAN models predicted more realistic transient behavior than the FSAR LOFTRAN results.