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:
e containment isolation provisions for each line penetrating the containment to determine that two isolation barriers in series are provided, and in conjunction with the PSBEELB by reviewing the power sources to the valve operators. 75 6.2.4-15 DRAFT Rev. 3 - April 1996 The CSBSCSB reviews the information in the SAR justifying containment isolation provisions 76 which differ from the explicit requirements of General Design Criteria 55, 56, and 57. The CSBSCSB judges the acceptability of these containment isolation provisions based on a 77 comparison with the acceptance criteria given in subsection II of this SRP section. The CSBSCSB reviews the position of isolation valves for normal and shutdown plant 78 operating conditions, postaccident conditions, and valve operator power failure conditions as listed in the SAR. The position of an isolation valve for each of the above conditions depends on the system function. In general, pPower-operated valves in fluid systems which do not have 79 a postaccident safety function (nonessential systems), as defined in Regulatory Guide 1.141)80 should close automatically. In the event of power failure to a valve operator, the valve position should be the position of greater safety, which is normally the postaccident position. However, special cases may arise and these will be considered on an individual basis in determining the acceptability of the prescribed valve positions. The CSBSCSB also ascertains from the SAR 81 that all power-operated isolation valves have position indication capability in the main control room. The CSBSCSB reviews the signals obtained from the plant protection system to initiate 82 containment isolation. In general, there should be a diversity of parameters sensed; e.g., abnormal conditions in the reactor coolant 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