Document: NUREG-0800
Document ID: d2f0cc81-920c-4065-b74b-67114ba68b0e
Document Type: srp
Title: through 7.9 of the SAR. Where exceptions are taken to the guidance provided by regulatory guides, and
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500493.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.2
CFR Part: 
CFR Title: 

Content:
ve basis, or on a line-by-line basis, provided that electrical independence and the single-failure criterion for the ESFAS functions continue to be satisfied. Ganged reopening of containment isolation valves is not acceptable. Draft Reg. Guide DG-1045 (the proposed revision 3 to Reg. Guide 1.105, "Instrument Setpoints for Safety Systems"), and BTP HICB-12 provide guidance on establishing and maintaining instrument setpoints. For isolation of nonessential containment penetrations, however, the trip setpoint should be established by adding measurement error terms to the highest pressure value expected during normal plant operations, rather than subtracting error terms from an accident analysis analytical limit. The setpoint should also be shown to be low enough to ensure protection system functions are actuated before analytical limits are reached. The pressure setpoint selected should be far enough above the maximum observed, or expected, pressure inside Rev. 4 — June 1997 SRP 7.1-A-5 containment during normal operation so that inadvertent containment isolation does not occur during normal operation from instrument drift or fluctuations due to the accuracy of the pressure sensor. The containment pressure history during normal operation should be used as a basis for arriving at an appropriate minimum pressure setpoint for initiating containment isolation. Applicants for new licenses should use pressure history data from similar plants that have operated for more than one year, if possible, to arrive at a minimum containment setpoint pressure. Containment purge lines and other penetrations that provide a path to the environment should be isolated on a high radiation signal as one of the diverse isolation functions. The review of these design provisions to address 10 CFR 50.34(f)(2)(xiv) should be addressed in the review of Section 7.3 of the SAR and should be coordinated with the Containment Systems and Severe Accident Branch (SCSB). NUREG-0737 provides additional