Document: NRC Regulatory Guide
Document ID: c256f223-ee35-43e0-82e7-aa7b14469259
Document Type: regulatory_guide
Title: Preoperational Testing of Emergency Core Cooling Systems for Pressurized Water Reactors + HISTORY - HISTORY DG-1253 , Proposed Revision 2 (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1101/ML110110480.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.79
CFR Part: 
CFR Title: 

Content:
3.0.3 A, Inoperable ECCS, Containment Spray, and Refueling Water Tank,” December 8, 2005. (ADAMS Accession No. ML053540220). Appendix A to DG-1253, Page A-1 APPENDIX A EMERGENCY CORE COOLING SYSTEMS DESIGN DESCRIPTIONS A.1 Emergency Core Cooling Systems for Current Pressurized-Water Reactors For additional design details, see NUREG/CR-5640/SAIC-89/1541, “Overview and Comparison of U.S. Commercial Nuclear Power Plants,” issued September 1990. Specifically, for pressurized-water reactors (PWRs), see Section 3.9, “Emergency Core Cooling Systems,” and Section 4.4, “4-Loop Westinghouse PWRs,” of that report. The emergency core cooling system (ECCS) for the current fleet of PWRs uses a high-pressure safety injection (HPSI) system except for two four-loop Westinghouse PWRs that use a medium-pressure safety injection (MPSI) system. The ECCS for the current fleet of PWRs also uses core flooding and a low-pressure safety injection (LPSI) system. A.2 U.S. Advanced Pressurized-Water Reactor Safety Injection System The U.S. Advanced Pressurized-Water Reactor (US-APWR) ECCS consists of the safety injection system (SIS) (Figure A.2-1), which includes the high-pressure injection system, the accumulator system, and the emergency letdown system. Figure A.2-1. US-APWR Safety Injection System Appendix A to DG-1253, Page A-2 The ECCS is designed to perform the following major safety-related functions: a. safety injection, b. safe shutdown, and c. containment pH control. These functions are provided by safety-related equipment with redundancy to deal with single failure, environmental qualification, and protection from external hazards. The ECCS automatically initiates with redundancy sufficient to ensure that these functions are accomplished, even in the unlikely event of the most limiting single failure occurring coincident with, or during, the event. The SIS, in conjunction with the rapid insertion of the control rod cluster assemblies (reactor scram), provides