An analysis consisting of several transients was performed to benchmark the RETRAN02 Mod5 model for LaSalle units 1 and 2 to startup test measurements. Benchmarks to startup tests are an important step in validating a RETRAN model. The five transients chosen were as follows: a two-recirculation-pump trip, a pressure regulator setpoint change, a feedwater level setpoint change, a full main-steam-line-isolation event, and a generator load rejection with bypass. These transients were chosen to examine different aspects of the RETRAN model to provide a complete test of each system.

Each of the five transients had a different set of initial conditions (e.g., power, flow). The RETRAN model was initialized at the startup test conditions, and the FIBWR2 code was used to determine the RETRAN inputs for the core pressure and bypass flow distributions. All of the RETRAN analyses used the RETRAN one-dimensional kinetics option, and the one-dimensional kinetics cross sections were developed based on Commonwealth Edison Company methodology. The LaSalle base model, transient specific changedeck, and transient specific cross-section file were used to initialize and facilitate each transient in RETRAN.

The RETRAN predictions for each transient were compared with the measured plant data. These comparisons were evaluated using a predetermined acceptance criterion. The parameters of interest for each of the startup tests were shown to be within the acceptance criterion. Therefore, the benchmark results provide a high confidence that the RETRAN model is a valid and accurate representation of the LaSalle County nuclear stations for a broad spectrum of transient analysis.