Document: NUREG-0800
Document ID: 57051ec2-9a01-488e-8294-573ed557f3eb
Document Type: srp
Title: GROUNDWATER
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070262.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.12
CFR Part: 
CFR Title: 

Content:
uxiliary holding pond 2.4.12-9 DRAFT Rev. 3 - April 1996 onsite. The underdrain system of connected flow channels will be located at the top of rock or at the top of first level of fill concrete below each foundation slab. Each channel will run the full length of the building excavation but will be closed at each end so that no sediment can be transported into it from backfill outside the walls. All channels in the grid system will drain by gravity through eight pipes to a 15-foot 4.6-m (15-ft) square 37 sump located inside the auxiliary building. The exterior wall drains will be located around the exterior walls of the auxiliary and reactor building and will drain to the same sump as the underdrain system. No connection between the wall drains and the underdrain system will exist such that each drains to the sump through independent and separate conduits. The exterior wall drain system will consist of a zoned filter system which extends from 5 feet 1.5 m (5 ft) below yard grade to the bottom of the 38 excavation. The continuous perforated pipe will extend around the perimeter of the building exterior walls at the bottom of the zoned wall filter. Two 120- gallon-per-minute 450-l- (120-gal-) per-min seismic Category I pumps will maintain 39 the water level automatically in the sump with each pump capable of handling the total computed flow of up to 1535 gallons 5810 l (1535 gal) per minute per unit. We 40 conclude that the system meets the requirements of General Design Criterion 5 in that those portions which are shared between reactor units have sufficient redundancies to enable them to perform their safety functions in the event of postulated single failures. The applicant will include provisions in the design for monitoring of pump operation, and visual inspection of drain outlets in the sump will provide assurance that the zoned filter, drains, and pumps are functioning properly. Seismic Category I manholes, located along the exterior walls of the reactor and