Document: NUREG-0800
Document ID: b4039863-44f0-46d9-979e-27ea871ff5d6
Document Type: srp
Title: -19
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1404/ML14043A231.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.3
CFR Part: 
CFR Title: 

Content:
Revision 3 – April 2014 For example, under the "faulted plant or system condition" (e.g., due to LOCA within the reactor coolant pressure boundary), the emergency core cooling system (ECCS) should be designed to operate and deliver rated flow for an extended period of time to ensure the safe shutdown of the plant. Although the "plant condition" is termed "faulted," components in the functional ECCS must perform the safety function under a specified set of service loadings which includes those resulting from the specified plant postulated events. The selection of Level "D" (related to the "faulted" condition) service stress limits for this system, based solely on the supposition that all components may use this limit for a postulated event resulting in the faulted plant condition cannot be justified, unless system functionality is also demonstrated. The objective of this appendix is to improve consistency and understanding of the basic approach in the selection of load combinations applicable to the subject components and structures, and to establish acceptable relationships between plant postulated events, plant and system operating conditions, component and component support design, and service stress limits, and functional capability. 2. DISCUSSION Reviews of both standardized plants and custom plants have indicated the need for additional guidance to reach acceptable design conclusions in the following areas: A. Relationship between certain plant postulated events, plant and system operating conditions, resulting loads and combinations thereof, and appropriate design and service stress limits for Code Class 1, 2, and 3 components and component supports, and core support structures. B. Relationship of component operational readiness assurance, functional capability, and allowable design and service stress limits for Code Class 1, 2, and 3 components and component supports, and core support structures. The Code provides five categories of limits applicable to