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:
levels for safety-related structures, systems, and components. The design basis groundwater level is defined as the maximum groundwater level used in the design analysis for dynamic or static loading conditions (whichever is being considered), and may be in excess of the elevation for which the underdrain system is designed for normal operation. This level should consider abnormal and rare events (such as an occurrence of the safe shutdown earthquake (SSE), a failure of a circulating water system pipe, or a single failure within the system), which can cause failure or overloading of the permanent dewatering system. (f) A single failure of a critical active feature or component must be postulated during any design basis event. Unless it can be documented that the potential consequences of the failure will not result in Regulatory Guides 1.26 and 1.29 dose guidelines being exceeded, either (1) document by pertinent analyses that groundwater level recovery times are sufficient to allow other forms of dewatering to be implemented before the design basis groundwater level is exceeded, discuss the measures to be implemented and equipment needed, and identify the amount of time required to accomplish each measure; or (2) design for all system components for all severe natural phenomena and events. For example, if the design basis groundwater level can be exceeded only as a result of a single nonseismically induced failure of any component or feature of the system, the staff may allow the design basis level of the dewatering system to be exceeded for a short period of time (say 2 or 3 days), provided that (1) effective alternate dewatering means can be implemented within this time period, or that (2) it can be shown that Regulatory Guides 1.26 and 1.29 guidelines will not be 2.4.12-21 DRAFT Rev. 3 - April 1996 exceeded by groundwater induced impairments of safety-related structures, systems, or components. (g) Where appropriate, document the bases which assure ensure the