Document: NUREG-0800
Document ID: f673d9c7-5410-4f11-8c45-1935b546a77f
Document Type: srp
Title: EMERGENCY DIESEL ENGINE COOLING WATER SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070570.pdf
Revision Date: 2023-06
Chapter: 9
Section ID: 9.5.5
CFR Part: 
CFR Title: 

Content:
and leaktightness, operability and performance of active components, and the capability of the system to function as intended under accident conditions. Plants that have emergency ac sources in excess of minimum redundancy requirements for loss-of-offsite-power conditions may use one of the existing emergency sources as an alternate ac (AAC) power source for the purposes of coping with a station blackout, provided it meets the applicable criteria for an AAC source. For a plant relying on an emergency diesel engine as an AAC power source, the design of the cooling water system for that engine is acceptable if it meets 10 CFR Part 50.63, paragraph (a)(2), and Regulatory Guide 1.155, Position C.3.41 DRAFT Rev. 3 - April 1996 9.5.5-6 Technical Rationale:42 The technical rationale for application of the above acceptance criteria to the emergency diesel engine cooling water system is discussed in the following paragraphs. 1. GDC 2 requires that SSC important to safety be designed to withstand the effects of natural phenomena such as earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches without loss of capability to perform the safety function. Regulatory Guide 1.117 provides the methods acceptable to the staff for tornado design classification of structures, systems and components important to safety. Position 13 of the appendix to Regulatory Guide 1.117 identifies Class 1E electrical systems that must be protected from the effects of tornadoes. The safety function of the EDECWS is to provide cooling water for the EDE following an engine start signal. A reliable cooling water supply to the emergency diesel engine is necessary to ensure the prompt restoration of ac power to safety related components that are necessary to maintain the integrity of the reactor coolant pressure boundary, to safely shutdown the reactor and maintain it in a safe shutdown condition, and to prevent or mitigate the consequences of accidents. Compliance with the requirements of GDC 2 and