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:
lation capability evaluation are appropriate for all water-cooled reactors. These areas include NPSH evaluation, selection of limiting pipe breaks, debris generation, debris transport, coating debris, latent debris, sump structure, downstream effects, chemical effects, structural analyses, and head loss testing. 1.1.1 Emergency Core Cooling System Sumps, Suppression Pools, Suction Strainers, and Debris Interceptors ECCS sumps and suppression pools should contain an appropriate combination of the features and capabilities listed below to ensure the availability of the water sources for long-term cooling. 1.1.1.1 A minimum of two independent ECCS suction strainers should be provided, each with sufficient capacity to accommodate the full plant debris loading while providing sufficient flow to one train of the ECCS and containment heat removal pumps. To the extent practicable, the redundant suction strainers should be physically separated from each other by structural barriers to preclude damage resulting from a LOCA, such as whipping pipes or high-velocity jet impingement. 1.1.1.2 The containment floor near floor-mounted ECCS strainers should slope gradually downward away from the strainers to retard floor debris transport and reduce the fraction of debris that might reach the suction strainer. Similar floor sloping should be used near a sump pit if the ECCS strainers are installed in a pit configuration. Debris interceptors or curbs can also be used to retard debris transport. 1.1.1.3 The inlet of pumps required for long-term cooling should be protected by a suction strainer placed upstream of the pumps to prevent the ingestion of debris that may damage components or block restrictions in the systems served by the pumps. 1.1.1.4 All drains from the upper regions of the containment should terminate so that streams of water will neither directly impinge on nor discharge close to the ECCS strainers. Streams of drainage from upper containment may contain entrained debris;