Document: NUREG-0800
Document ID: c23d52ec-d83f-4468-b35e-e8c97fdf2f09
Document Type: srp
Title: CONTAINMENT ISOLATION SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070461.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.4
CFR Part: 
CFR Title: 

Content:
olant system, the secondary coolant system, and the containment, which generate containment isolation signals. Since plant designs differ in this regard and many different combinations of signals from the plant protection system are used to initiate containment isolation, the CSBSCSB considers the arrangement proposed on an 83 individual basis in determining the overall acceptability of the containment isolation signals. The CSBSCSB will use the guidance presented in Item II.E.4.2. of NUREG-0737 for its 84 review ofreviews the containment setpoint pressure that initiates containment isolation for 85 nonessential penetrations. This pressure setpoint should be the minimum value that is compatible with normal operating conditionsoperation, . as required by 86 10 CFR 50.34(f)(2)(xiv)(D). Additional guidance for review of this setpoint is contained in Item II.E.4.2 of NUREG-0737.87 The CSBSCSB reviews isolation valve closure times. In general, valve closure times should be 88 less than one minute, regardless of valve size. (See the acceptance criteria for valve closure times in subsection II of this SRP section.) Valves in lines that provide a direct path to the environs, e.g., the containment purge and ventilation system lines and main steam lines for direct cycle plants, may have to close in times much shorter than one minute. Closure times for these valves may be dictated by radiological dose analyses or ECCS performance considerations. The CSBSCSB will request the AEBPERB or RSBSRXB to review analyses justifying valve 89 90 91 closure times for these valves as necessary. The CSBSCSB determines the acceptability of the use of closed systems inside containment as 92 isolation barriers by comparing the system designs to the acceptance criteria specified in subsection II of this SRP section. The MEBEMEB and SEBECGB have review responsibility for the structural design of the 93 94 containment internal structures and piping systems, including restraints, to ensure that the