Document: NUREG-0800
Document ID: 6237521d-c825-4ed6-8fb7-7b3b8019a3fc
Document Type: srp
Title: SYSTEM QUALITY GROUP CLASSIFICATION
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070297.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.2.2
CFR Part: 
CFR Title: 

Content:
ection 6.2.4 contains guidance related to classification of containment isolation systems. Containment isolation system components (e.g., isolation barriers) are normally classified as Quality Group B unless their service function dictates that Quality Group A standards be applied. Reg. Guides 1.11 and 1.141 are cited in SRP Section 6.2.4 and DRAFT Rev. 2 - April 1996 3.2.2-26 describe methods acceptable to the NRC staff for complying with the Commission's requirements with respect to containment isolation of fluid systems.170 (3) Reg. Guide 1.11 describes a suitable basis which may be used to implement containment isolation design requirements for instrument lines. Position C.1.c indicates that protection system sensing lines penetrating or connected to primary reactor containment should be provided with an isolation valve capable of automatic operation or remote operation, and located in the line outside the containment as close to the containment as practical. Position C.1.d indicates that such lines should be conservatively designed up to and including the isolation valve and of a quality at least equivalent to the containment [generally Group B per NOTE (2) above]. Position C.2 indicates that sensing lines for instruments that are not part of the protection system should meet the above provisions or should be provided with one automatic isolation valve inside and one automatic valve outside containment as close to containment as practical.171 (4) Branch Technical Position CSB 6-3, attached to SRP Section 6.2.3, describes methods for determining bypass leakage paths in dual containment plants. Position B.9.b indicates that closed systems proposed as a leakage boundary to preclude bypass leakage should be designed in accordance with Quality Group B standards, as defined by Regulatory Guide 1.26, but that systems designed to Quality Group C or D standards that qualify as closed systems to preclude bypass leakage will be considered on a case-by-case basis.172 (5)