Document: NRC Regulatory Guide
Document ID: 6f0a99f2-d25a-44e3-b7f2-3286449a9752
Document Type: regulatory_guide
Title: Water Sources for Long-Term Recirculation Cooling Following a Loss-of-Coolant Accident (Rev. 5)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2126/ML21266A185.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.82
CFR Part: 
CFR Title: 

Content:
2019, ADAMS Accession No. ML18093B087. DG-1385, Appendix A, Page A-1 APPENDIX A ADDITIONAL GUIDELINES FOR THE REVIEW OF HYDRAULIC PERFORMANCE OF WATER SOURCES FOR EMERGENCY CORE COOLING SYSTEMS Water sources for long-term recirculation should be evaluated under possible conditions after a loss-of-coolant accident (LOCA) to determine the adequacy of their design for providing long-term recirculation. Areas for technical evaluations can be subdivided into (1) emergency core cooling system (ECCS) strainer hydraulic performance, (2) pump suction inlet hydraulic performance, (3) LOCA-induced debris effects, and (4) impacts of ingested air on pump performance. Figure A-1 identifies specific considerations within these categories and the combination thereof. The primary acceptance criterion is that adequate net positive suction head (NPSH) margin exists at the pump inlet under all postulated post-LOCA conditions such that the required coolant flow is delivered to the reactor. However, other potential failure modes, such as structural failure, flashing or deaeration as coolant flows through the strainer, and insufficient flow (for partially submerged or vented strainers), should also be considered as applicable, as discussed in the regulatory positions. Figure A-1 Technical considerations relevant to ECCS suction strainer performance • Types, Quantities, and Location of Insulation • Containment Layout and Break Locations • Estimated Quantity of Debris Generated • Chemical Byproducts • Latent Debris • Coating Debris DEBRIS POOL/SUMPS PUMPS • Location in Plant: Redundancy • Geometric Parameters • Strainers, Interceptors (Racks, Screens), Covers, etc. • Pump Design and Operating Characteristics • NPSH Requirements (No Air) • Strainer and Suction Piping—Losses • Short-Term Transport by Blowdown Jet • Long-Term Transport by Recirculation Velocities • Debris Transport by Containment Spray Washdown • Hydraulic Characteristics - Water Level above