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:
tructures, systems and compo- nents from the effects of natural and man-caused events such as groundwater. In addition, the level of documentation of data and studies which are considered necessary to support safety-related functions is defined. This position applies to both active (e.g., uses pumps) and passive (e.g., uses gravity drains) dewatering systems. This position does not reflect structural, mechanical, and electrical criteria. II. Background The staff has reviewed a number of permanent dewatering systems, including McGuire 1 & 2, Cherokee 1 & 2, Perkins 1 & 2, Perry 1 & 2, WPPSS 3 & 5, Douglas Point 1 & 2, and Catawba 1 & 2. Perry, beginning in 1975, was the first plant reviewed with such systems, and was reviewed very late in the CP process. Only WPPSS 3 & 5 and Douglas Point use a passive system (no pumps). Permanent dewatering systems lower groundwater levels to reduce subsurface water loads on plant structures. In addition, they can increase plant operational dependability and reduce costs. These effects are accomplished by providing added means of keeping seepage water out of lower building levels during the later stages of plant life when normal waterproofing provisions may have deteriorated, and reducing radwaste system operating costs by minimizing the amount of drain water that must be treated. Benefits are, therefore, of two types, tangible (dollars) and intangible ("insurance"). We understand the construction costs of underdrains can vary widely depending on the design. Construction costs of between $125K to $1000K per unit have been suggested. The costs of coping with significant amounts of groundwater inleakage in safety- related building areas, which underdrains are expected to minimize, is estimated to be in the range of $100K to $200K per year per reactor. The construction costs of alternatives to underdrains for structural purposes alone (exclusive of inleakage treatment) is estimated to range upward from $300K per unit and is highly