Document: NUREG-0800
Document ID: 217f75d5-3db3-41ce-939d-8f7a5fcf0f68
Document Type: srp
Title: feet 0.76 m (2.5 ft).   The applicant in Section 2.4.12 of the PSAR has described the
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070262.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.5
CFR Part: 
CFR Title: 

Content:
47 consequences of other accidents and additional design changes that were made to mitigate the consequences of the accidents. Although the accidents do not include all conceivable events that could result in excess flow into the sump, the applicant proposes to use the break of the nuclear service water pipe as the design basis event for evaluating sump overflow. It would appear that alternate designs, such as higher sump walls, could be readily implemented as a backup design feature if other sources result in unacceptable sump overflow. We conclude that the applicant's criteria for limiting sump overflow, or utilization of modifications to the preliminary design, if necessary, provide assurance that a design can be developed that will provide adequate flood protection for systems and components located in the shield and auxiliary buildings and thus meets the requirements of 10 CFR Part 50, §50.55a, and General Design Criterion GDC 4. In response to our concerns about potential blockage of flow paths from the wall drain to the sump, the applicant has committed, as described in Section 3.8.5 of this report, to design external structural walls surrounded by wall drains and foundation floors to withstand as an extreme environmental load the hydrostatic load caused by postulated rebound of water in the wall drains to plant grade even though no specific mechanism for effecting such a rebound has been postulated. We conclude that this commitment is a conservative approach with respect to maximum design water level in the wall drain and meets the requirements of General Design Criteria 2 and 4. For an application referencing a certified plant design, the reviewer's findings should include a concluding statement similar to the following: Groundwater data for the proposed site are consistent with the groundwater level identified in the site parameter envelope specified in the certified plant design documents.48 For design certification reviews, the findings will also