Document: NUREG-0800
Document ID: ea7ce8f5-32bf-4d8c-a653-e964bff0ef48
Document Type: srp
Title: EMERGENCY CORE COOLING SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070448.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.3
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Content:
of LPCS and LPCI after manual trip for BWR plants.78 8. Task Action Plan Item II.K.3(39) of NUREG-0660 which involves evaluation of effects of water slugs in piping caused by HPI and CFT flows in B&W plants.79 In addition to the above criteria, the acceptability of the ECCS may be based on the degree of design similarity with previously approved plants. Technical Rationale:80 The technical rationale for application of the above acceptance criteria to the emergency core cooling system is addressed in the following paragraphs: 1. GDC 2 requires that SSCs important to safety be designed to withstand the effects of natural phenomena without the loss of capability to perform their safety functions. The ECCS is relied upon to provide sufficient emergency core cooling flow to protect the integrity of the reactor core during postulated accidents, including the loss-of-coolant accident. Regulatory Guide 1.29 provides guidance for determining which SSCs should be designed to withstand the safe shutdown earthquake (SSE). Position C.2 recommends that SSCs whose continued function is not required but whose failure could reduce the functioning of the ECCS to an unacceptable safety level should be designed and constructed to withstand the SSE. Meeting the requirements of GDC 2, and positions of Regulatory Guide 1.29, enhances plant safety by ensuring the integrity of Seismic Category I portions of the ECCS and thus the capability to provide core cooling following a seismic event. 2. GDC 4 requires that SSCs important to safety be designed to accommodate the effects of and be compatible with the environmental conditions associated with normal operation, maintenance, testing and postulated accident conditions. These conditions include consideration of the dynamic effects of flow instabilities and the loadings caused by water hammer events. The ECCS provides emergency core cooling in the event that normal cooling methods are not available or are insufficient. Compliance with GDC 4