Document: NUREG-0800
Document ID: 4f5104c1-f91e-4f7d-a8f7-b8b18e630618
Document Type: srp
Title: INTERNAL FLOOD PROTECTION FOR ONSITE EQUIPMENT FAILURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550043.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.4.1
CFR Part: 
CFR Title: 

Content:
identified SRP acceptance criteria. For deviations from these acceptance criteria, the staff should review the applicant’s evaluation of how the proposed alternatives provide an acceptable method of complying with the relevant NRC requirements identified in Subsection II. 1. An evaluation of the SSCs in the SAR that are safety-related and should be protected against floods or flood conditions. 2. An evaluation using the plant arrangement, layout drawings and any other acceptable methods to assess the adequacy of techniques such as enclosures, pumping systems, drains, internal curbs, and watertight doors used to prevent flooding of safety-related systems or components. The measures for protecting against external flooding are reviewed by and coordinated with the organization responsible for the review of SRP Sections 2.4.1 through 2.4.14. 3. An assessment of the potential flooding of SSCs important to safety due to the operation of the fire protection system and the postulated failure of piping in accordance with SRP Section 3.6.2, as well as postulated failures of non-seismic and non-tornado protected piping, tanks, and vessels. For the purposes of flood analysis, the reviewer need only assume, for each analyzed area, the rupture of the single, worst-case pipe (or non-seismic tank/vessel). Moderate energy piping that is not seismically supported should be considered for full circumferential ruptures, not just cracks. Appendix A to SRP Section 3.6.2, only considers cracks in moderate energy piping. However, this Appendix applies during normal conditions, not seismic events. This assessment should consider ways to mitigate the consequences of potential internal flooding to safety-related systems, such as drains and sump pumps. If a postulated break is in a non-seismically supported system, then only seismically-qualified systems should be assumed to be available to mitigate the effects of the analyzed break (since a seismic event may have caused the failure).