Methodology for Evaluation of Insulation Debris Effects: Containment Emergency Sump Performance, Unresolved Safety Issue A-43.

摘要

The postulated failure of high energy piping within a light water reactor containment has raised safety questions related to the generation of insulation debris, the migration of such debris to the containment emergency sump screens and the potential for severe screen blockages. High, or total, screen blockages could result in impairment of the long-term RHR recirculation systems. Debris considerations are an integral part of the Unresolved Safety Issue A-43, 'Containment Emergency Sump Performance.' This report develops calculational methods and debris transport models which can be used for estimating the quantities of debris that might be generated by a LOCA, the transport of such debris, methods for estimating screen blockages and attendant pressure losses. Conservative assumptions are employed and the calculations are shown to be plant specific since the types and quantities of insulation, equipment location, and break locations establish initiating events. Plant layout and sump location, which determine migration paths, are also important. Calculational procedures for estimating break jet impingement effects and blocked screen pressure losses are included. Five operating plants which were analyzed using this debris evaluation methodology are given in the Appendices. The calculation clearly illustrate plant dependency.