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:
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 systems (no pumps). 54 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 dependent on site conditions. Structural alternatives to permanent underdrains include additional concrete and steel in the lower portions of buildings, and the use of anchor systems to resist flotation. Dewatering systems are generally composed of three components: the collector system, the drain system, and the discharge system. Water is first collected in collector drains adjacent to buildings or excavations. Interceptor drains or piping are then used to convey this water to a final discharge system. The discharge system can be either gravity flow or a pumping system. Most underdrain