Document: NUREG-0800
Document ID: b1bccb14-17b6-422b-93ee-6d4f00b6512b
Document Type: srp
Title: CHILLED WATER SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1510/ML15103A559.pdf
Revision Date: 2023-06
Chapter: 9
Section ID: 9.2.7
CFR Part: 
CFR Title: 

Content:
• Safety-related risk-significant 1 The “post 72-hour period” as stated in SRP 19.3 is defined as the period beginning 72 hours after a design basis event and lasting the following 4 days. This period is important from a safety perspective because passive plants are designed such that safety-related SSCs can satisfy all safety functions for a period up to 72 hours following a design basis event, but additional equipment and procedural action will be needed to either extend the ability of safety-related SSCs to accomplish the safety functions or perform the safety functions themselves until systems designed to bring the plant to a long-term cold shutdown condition can be put in service. 9.2.7-3 Revision 0 – September 2015 • Safety-related nonrisk-significant • Nonsafety-related risk-significant, which may include RTNSS Criterion B and RTNSS Criterion C SSCs • Nonsafety-related nonrisk-significant, which may include functions to support cold shutdown (CSD) conditions The application will include the classification of SSCs, a list of risk-significant SSCs, and a list of RTNSS equipment. Based on this information, the staff will review the information according to SRP Sections 3.2.1, “Seismic Classification,” 3.2.2, “System Quality Group Classification,” 17.4, Reliability Assurance Program (RAP)”, and 19.3 to confirm the determination of the safety-related and risk-significant SSCs.Defense-in-depth principles consist of a number of elements as described in Regulatory Guide (RG) 1.174, “An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant Specific Changes to the Licensing Basis.” The specific areas of review are as follows: 1. Review safety/risk-significant classification as discussed above. 2. Compliance with the requirements of General Design Criteria (GDCs) 1, 2, 4, 5, 44, 45, and 46 for CWS SSCs. 3. The capability of the CWS to provide adequate cooling water to safety-related ECCS components,