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:
t) above the turbine 43 building floor. The wall of the adjacent auxiliary building facing the turbine building will be constructed as a seismic Category I wall up to a level of 13 feet 6 inches 4.1 m (13 ft, 6 in)44 above the turbine floor to prevent flow of the ponded water in the turbine building into the auxiliary building. In addition, the applicant proposes to place a grout curtain under this wall to reduce seepage to the underdrain system and to extend seismic Category I retaining walls outward from the auxiliary building to retain a column of low permeability soil as a barrier to flow of water from the turbine building around to wall drains along the sides of the auxiliary building. The primary grout holes for the grout curtain below the auxiliary building substructure mat and the retaining wall will be spaced at 20-foot 6-m (20-ft) intervals. Secondary holes will 45 split-space the primary grout holes. After the grout curtain is completed, with a maximum hole spacing of 10 feet 3 m (10 ft) center-to-center, four core holes will be drilled to verify 46 the adequacy of the grout curtain. Along with visual inspection of the rock cores, the holes will be water tested to assure to ensure that the permeability of the grout curtain is less than the average permeability of continuous rock. The grout holes are to be split-spaced until the equality in permeability is attained. After completion of the grouting and testing, the four test holes will be cased and maintained for observation and testing throughout the life of the plant. We conclude that the criteria for the design of retaining wall and placement of the grout curtain meet the requirements of General Design Criterion GDC 4 and are acceptable and should result in an acceptable means of preventing leakage from the turbine building to the 2.4.12-11 DRAFT Rev. 3 - April 1996 permanent dewatering system. In the event of a circulating water system pipe rupture outside of the turbine building, the applicant has