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:
prevent or control valve stem or packing leakage or other direct leakage from main steam m line isolation valves outside containment. If such equip ment is not part of the LCS, it should meet the same design standards as the LCS. its er D. IMPLEMENTATION The purpose of this section is to provide information nt to applicants and licensees regarding the NRC staff's in plans for using this regulatory guide. as This guide reflects current regulatory practice. There fore, except in those cases in which the applicant ly proposes an acceptable alternative method for comply on ing with specified portions of the Commission's regula sis tions, the method described herein is being and will nt continue to be used in evaluating submittals for con :al struction permit and operating license applications. Although this guide may recommend backfitting in certain cases that have already been docketed, as he described below, it does not require it. Such require ce ments will be formulated on an individual basis pursuant ty to 10CFR §50.109. 1. In the case of boiling water reactor plants for to which construction permits were issued prior to March 1r, 1, 1970 (see Table 1), applicants and licensees should he continue the established inservice inspection programs to to ensure that isolation valves are maintained in such a n- manner that leakage is within Technical Specification rig limits. If the valve inspections show recurring problems nt with excessive leakage, the staff recommends that !re consideration be given to installation of a supplementary be leakage control system. he .at 2. In the case of boiling water reactor plants of ly designs preceding the BWR 6/Mark III design and for be which construction permits have been issued after March or 1, 1970 (see Table 1), the staff recommends that applicants and licensees install a supplemental leakage 1.96-3 control system. Leakage control systems for these plants should be designed in accordance with the recommend ations in the