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:
, and that ganged reopening of isolation valves is not possible. The SCSB evaluates the design features of the purging/venting system that are provided to minimize purging time and verifies that there is a high degree of assurance that the purge system will reliably isolate under accident conditions.110 6.2.4-17 DRAFT Rev. 3 - April 1996 The SCSB verifies that appropriate containment integrity is maintained in the event of a station blackout. This means that adequate containment integrity is ensured by providing the capability, independent of the preferred and blacked-out unit's onsite emergency ac power supplies, for valve position indication and closure for containment isolation valves that may be in the open position at the onset of a station blackout. Certain containment isolation valves are excluded from consideration, as discussed in Regulatory Guide 1.155.111 For PWRs, the SCSB verifies that sufficient procedures and controls are in place that will reasonably assure that containment closure (as defined in reference 24) is possible during reduced inventory conditions. Containment closure must be achieved prior to the time at which an uncovered core could result from a loss of decay heat removal coupled with an inability to initiate alternate cooling or addition of water to the RCS inventory. These controls should be in use: (a) prior to entering a reduced RCS inventory condition for NSSSs supplied by Combustion Engineering or Westinghouse, and (b) prior to entering an RCS condition wherein the water level is lower than four inches below the top of the flow area of the hot legs at the junction of the hot legs to the RV for NSSSs supplied by Babcock and Wilcock.112 For standard design certification reviews under 10 CFR Part 52, the procedures above should be followed, as modified by the procedures in SRP Section 14.3 (proposed), to verify that the design set forth in the standard safety analysis report, including inspections, tests, analysis, and acceptance