Document: NUREG-0800
Document ID: 48fb37ec-8e3e-4c2c-96c3-daa5e7da62f9
Document Type: srp
Title: of the applicant's SAR is reviewed to identify any missing data,
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340557.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.12
CFR Part: 
CFR Title: 

Content:
ents that could result in excess flow into the sump, the appli- cant 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 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 struc- tural walls surrounded by wall drains and foundation floors to with- stand 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 2.4.12-7 Rev. 2 - July 1981 approach with respect to maximum design water level in the wall drain and meets the requirements of General Design Criteria 2 and 4. V. IMPLEMENTATION The following is intented to provide guidance to-applicants and licensees regarding the NRC staff's plans for using this SRP section. Except in those -cases in which the applicant proposes an acceptable alternative method for complying with specified portions of the Commission's regulations, the method described herein will be used by the staff in its evaluation of conformance with Commission regulations. Implementation schedules for conformance to parts of the method discussed herein are contained in the