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:
truction excavation and dewatering data in the final design of underdrain systems. (See situation (d) below.) (b) Operational Monitoring Requirements To guard against system malfunctions and to assure sufficient time is available for implementation of remedial measures before ground- water could rise to an unacceptable level, provisions must be made for early detection of system failures, and contingency measures for these failures must be well defined prior to plant operation. Since drain systems are usually buried and concealed and there may be no direct way of inspecting them, reliance must be placed on piezometers, observation wells, manholes, and monitoring of collected water to detect problems or malfunctioning of the system. The details of an operational monitoring program are necessary prior to construction of the underdrain to assure that each of the following will be pro- vided: (1) an early detection alarm system during normal operating conditions; (2) regularly scheduled inspection and monitoring; and (3) competent evaluation of observations during both construction and operation. In addition, the bases for acceptable contingency measures suitable for coping with various possible hazards must be established at the CP stage. (c) Pipe Breaks A dewatering system might be overloaded by such conditions as leaks or breaks in.either the circulating or service water systems. A leak through a pipe break may be a very small percentage of the total flow of the cooling water system, but large enough to exceed the hydraulic capacity of drains, pipes and pumps in the dewatering system. For example, a complete failure of circulating water system piping has been required in the design of the dewatering systems reviewed to date. This requirement was made to assure that such abnormal occur- rences do not adversely affect the integrity of safety-related structures, systems, and components. (d) Sequence of Review Underdrain systems are usually one of the first items