Abstract
Accurate calculation of pump performance margins relative to test acceptance criteria are driven by a variety of requirements and constraints. Inputs including design basis required performance, acceptance criteria assumptions, test conditions, and field versus vendor data are required. Test margin with respect to safety analysis limits may be more limiting than ASME Operations and Maintenance (OM) Code [1] inservice testing (IST) requirements. In response to component design basis inspection (CDBI) and design basis assurance inspection (DBAI) findings of potentially non-conservative equipment performance when operating at the extremes of Emergency Diesel Generator (EDG) Technical Specification (TS) limits of frequency and voltage, Westinghouse and the Pressurized Water Reactor Owner’s Group (PWROG) developed WCAP-17308-NP-A [2] to provide a simplified approach to incorporate these limits, by treating them as uncertainties, into design basis pump test acceptance criteria. The basic methodology provides a general approach to account for uncertainties by adjusting pump curves and test acceptance criteria. Depending on the magnitude of the EDG and instrument uncertainties, adjusted design basis related test acceptance criteria may challenge the tested performance of the pumps. Margin can be recovered by reducing uncertainties and taking credit for any available margin in the safety analyses.
