Document: NUREG-0800
Document ID: c0d3006a-c4ee-4659-b650-837c0c94b143
Document Type: srp
Title: STABILITY OF SUBSURFACE MATERIALS AND FOUNDATIONS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340604.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.5.4
CFR Part: 
CFR Title: 

Content:
contains slightly weathered to unweathered slate and is encountered at depths of 60 to 90 ft below ground surface. The site area will be leveled to about elevation +390 feet msl, and containments will be founded on a 10 foot thick, reinforced concrete mat on slightly weathered slate or fill concrete over slightly weathered slate. The reactor service building between the reactors and the control building will be on mats at elevation +385 feet msl on compacted structural fill resting on slightly to moderately weathered rock. The turbine generators will be founded on compacted structural fill over moderately weathered rock at elevation +380 feet msl. The diesel generator building, reactor 2.5.4-14 Rev. 2 - July 1981 . plant component air-cooled heat exchanger enclosures, and the CACS air- cooled heat exchanger will be founded on either individual concrete -footings or continuous footings (grade beams) at +385 feet msl, on compacted structural fill over moderately weathered slate. Allowable bearing capacities from laboratory tests and field plate tests for Zone 1, Zone 2, and Zone 3 materials are 4, 10, and 25 tons per square foot, respectively. All piping will be entrenched and bedded in moderately to severely weathered slate. Settlement and differential settlement of safety-related facilities has been estimated to be less than one inch. The applicant states that severely weathered or soft zones of rock will be excavated and replaced with lean concrete. This procedure will also be followed wherever severe weathering extends along joints, schistosity, etc., below the base of the foundations; this material will be excavated to a depth 1-1/2 times the width of the zone and backfilled with concrete. Category I structural backfill under structures will either be concrete or compacted granular backfill. If granular backfill is used, it will be compacted to at least 85 percent relative density or to 95 percent of the maximum density determined by the Modified Proctor test.