Comparison of the behavior of Westinghouse and combustion engineering NPPS during a small break loss of coolant accident

Comparison is made between RELAP5 computations of the worst case Small Break Loss of Coolant Accident (SBLOCA) for a Westinghouse (W) RESAR-3S plant and a Combustion Engineering (CE) System 80 plant. The results indicate substantial differences in expected behaviors due to geometrical differences between the two plants and differences in the high pressure safety injection system (HPSI) characteristics. Predictions indicate that core uncovery in the CE System 80 plant would occur much later than it would occur in the Westinghouse RESAR-3S plant. In addition, the study indicates substantial sensitivity to both modeling techniques and computer code models. Thus, computations of this transient must be carefully examined before conclusions are drawn by the analyst and/or regulators