Document: NRC Regulatory Guide
Document ID: cf1737d6-2a8a-4765-aaf5-f5f2a617ef91
Document Type: regulatory_guide
Title: Design of Main Steam Isolation Valve Leakage Control Systems for Boiling Water Reactor Nuclear Power Plants
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740263.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.96
CFR Part: 
CFR Title: 

Content:
U.S. NUCLEAR REGULATORY COMMISSION REGULATORY GUIDE OiFFICE OF STANDARDS DEVELOPMENT REGULATORY GUIDE 1.96 DESIGN OF MAIN STEAM ISOLATION VALVE LEAKAGE CONTROL SYSTEMS FOR BOILING WATER REACTOR NUCLEAR POWER PLANTS A. INTRODUCTION General. Design Criterion 54, "Piping Systems Pene trating Containment," of Appendix A, "General Design Criteria," to 10 CFR Part 50, "Licensing of Production and Utilization Facilities," requires, in part, that piping systems penetrating primary containment be provided with leak detection, isolation, and containment capabili ties having redundancy, reliability, and performance capabilities that reflect the impoitance to safety of iso lating these piping systems. This guide describes a basis acceptable to the NRC staff for implementing General Design Criterion 54 with regard to the design of a leakage control system for the main steam isolation valves of boiling water reactor (BWR) nuclear power plants to ensure that total site radiological effects do not exceed guidelines of 10 CFR Part 100, "Reactor Site Criteria," in the event of a postulated design-basis loss-of-coolant accident (LOCA). If an applicant pro poses to use a method different from that described in this guide for implementing General Design Criterion 54 with regard to the control or limitation of leakage past the main steam isolation valves of a boiling water reactor, the acceptability of the alternative method will .be determined by the staff on a case-by-case basis. The Advisory Committee on Reactor Safeguards has been consulted concerning this guide and has concurred in the regulatory position. B. DISCUSSION Direct cycle boiling water nuclear power plants supply steam directly from the reactor vessel to the turbine via main steam lines. The main steam lines installed on current BWR plants are provided with dual quick-closing isolation valves. These valves function to *Lines indicate substantive changes from previous Issue. isolate the reactor system in the event of a