Document: NUREG-0800
Document ID: bdca3953-6a19-46c2-af2d-cb1ebbce1d89
Document Type: srp
Title: SAFE SHUTDOWN SYSTEMS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350476.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.4
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CFR Title: 

Content:
REVIEW RESPONSIBILITIES Primary - Instrumentation and Control Systems Branch (ICSB) Secondary - None I. AREAS OF REVIEW The areas reviewed in this section of the applicant's safety analysis report (SAR) include those instrumentation and control systems-associated with systems used to achieve and maintain a safe shutdown condition of the plant. To the extent that the engineered safety feature (ESF) systems are used to achieve and maintain safe shutdown, the review of these systems in this section is limited to those features which are unique to safe shutdown and not directly related to accident mitigation. Such features may involve individual component control for safe shutdown versus sytem level actuation for accident mitigation or system operating modes which involve considerations which differ for safe shutdown and accident mitigation. This SRP section also addresses the review of those systems required for safe shutdown which are not classified as ESF systems. The specific arrangement of these systems depends on the type of plant (pressurized water reactor, PWR; boiling water reactor, BWR; etc.) as well as on individual plant design features, and the conditions under.which the safe shutdown has to be achieved and maintained. The functional performance requirements of safe shut- down systems and essential auxiliary supporting systems are reviewed by other branches in accordance with the SRP sections which address these systems. There are two kinds of shutdown conditions: hot shutdown and cold shutdown. In either case, it is necessary that reactivity control systems maintain a sub- critical condition of the core and that residual heat removal systems operate to maintain adequate cooling of the core. For a precise definition of both shutdown conditions for a specific plant, see Chapter 16, "Technical Specifications," in the applicant's safety analysis report (SAR).