Analysis of Hatch-2 two recirculation pump trip startup test

A two recirculation pump trip test, conducted as a part of the Edwin I. Hatch Nuclear Plant Unit 2 (Hatch-2), a 2436 MWt BWR/4, startup testing, is analyzed using one-dimensional reactor kinetics and point reactor kinetics options in RETRAN-02 MOD002. The nuclear data utilized in RETRAN is obtained by SIMTRAN using the three-dimensional core simulator solution by SIMULATE (RTS/7), taking into account exposure and the steady-state core conditions prior to the test. Scram does not occur despite the actual sensed water level rise of about 17 inches (water level had initially been lowered), while core power, flow, and pressure continue dropping until the natural circulation establishes a new equilibrium condition at a lower reactor power level. A combined interaction of system components is taken into account by interfacing a detailed hydraulic model of the system, with control system models for feedwater flow and steam line pressure regulation using actual plant settings. Analysis of the actual data recorded during the dual recirculation pump trip test indicates good agreement between measured and calculated parameters. It is also demonstrated that in spite of rather large changes in the axial power distribution with time as predicted by one-dimensional reactor kinetics compared with that of point model, a good overall agreement is reached