Code scaling applicability and uncertainty applied to an SBLOCA: Sensitivity calculations and results

The U.S. Nuclear Regulatory Commission (NRC) revised the emergency core cooling system (ECCS) licensing rule to allow the use of best-estimate (BE) computer codes, provided that the uncertainties of the calculations are quantified and used in the licensing and regulation process. The NRC developed a generic methodology called code, scaling, applicability and uncertainty (CSAU) to evaluate BE code uncertainties. The CSAU methodology was developed and demonstrated with a specific application to a Westinghouse pressurized water reactor (PWR) experiencing a postulated large-break loss-of-coolant accident (LBLOCA), using TRAC as the BE code. The objective of this work was to adapt and demonstrate the CSAU methodology for a small-break (SB) LOCA in a PWR of Babcock and Wilcox (B and W) design, using RELAP5/MOD3 as the simulation tool.