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:
ncovery Unlike earlier strainer designs, the new generation of suction strainer designs that consist of a series of modules connected by piping may be susceptible to uncovery of piping internal to the strainer. For such a strainer design, uncovery of internal piping is possible if a complete water seal does not exist over all strainer surfaces; this represents an additional failure criterion that should be analyzed or addressed in some other manner. Figure A-3d illustrates the partial uncovery of suction piping for a partially submerged strainer. Failure could occur if the internal suction pipes connecting different strainer modules become uncovered. Such uncovery could severely affect the head loss and could lead to air or gas ingestion. This scenario should be avoided by ensuring that strainers with designs similar to that shown in Figure A-3d are fully submerged whenever there is flow through the strainer. DG-1385, Appendix A, Page A-12 Figure A-3d Internal suction line uncovery DG-1385, Appendix A, Page A-13 ACRONYM LIST ADAMS Agencywide Documents Access and Management System BWR boiling-water reactor ECCS emergency core cooling system GSI Generic Safety Issue LOCA loss-of-coolant accident NEI Nuclear Energy Institute NPSH net positive suction head NPSHa net positive suction head available NPSH margin net positive suction head margin (NPSHa – NPSHr) NPSHr net positive suction head required NRC U.S. Nuclear Regulatory Commission PWR pressurized-water reactor DG-1385, Appendix A, Page A-14 REFERENCES A-1. U.S. Nuclear Regulatory Commission, “A Parametric Study of Containment Emergency Sump Performance,” NUREG/CR-2758, July 1982, Agencywide Documents Access and Management System (ADAMS) Accession No. ML112440059. A-2. U.S. Nuclear Regulatory Commission, “GSI-191 Technical Assessment,” NUREG/CR-6762, Vols. 1–4, August 2002, ADAMS Accession Nos. ML022470077 (package), ML022470093, ML022480182, and ML022480262. A-3. U.S. Nuclear Regulatory Commission,