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:
nction is to spray water from the suppression pool into the core following a LOCA. During normal operation, they are in standby except for surveillance testing in accordance with the ASME Code and the plant’s TS. Pressurized-Water Reactor Pumps The pressurized-water reactor (PWR) pumps for which licensees may use CAP in determining the NPSH margin are the RHR and CS pumps. The RHR pumps are typically single-stage, low-head, high-capacity pumps. The functions of the RHR system are the following: • emergency coolant injection following a LOCA • cooling of the reactor coolant system during normal reactor shutdown The PWR CS pumps are single-stage, low-head, high-flow-rate pumps. The function of the containment spray system is to cool the containment by spraying water following a LOCA. The pumps are in standby during normal plant operation. B-3 Regulatory Requirements and Guidance As part of reactor safety analysis, licensees must demonstrate that the ECCS pumps and containment heat removal pumps will perform their safety functions of delivering flow for emergency core cooling and containment cooling respectively, as required by Title 10 of the Code of Federal Regulations (10 CFR) Part 50, “Domestic Licensing of Production and Utilization Facilities,” Appendix A, “General Design Criteria for Nuclear Power Plants,” General Design Criterion (GDC) 35, “Emergency core cooling,” and of rapidly reducing the containment pressure and temperature following a DG-1385, Appendix B, Page B-4 LOCA, as required by GDC 38, “Containment heat removal.” The ECCS pumps must perform their safety functions during a LOCA to satisfy the requirements of 10 CFR 50.46, “Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.” In this regulatory guide, Position C.1.3.1.1 states the following: The design of the ECCS and containment heat removal system should ensure that sufficient NPSHa is provided to the system pumps, assuming the