Document: NUREG-0800
Document ID: 5c84a1c2-9405-4849-8c5f-415a0bb66a22
Document Type: srp
Title: in connection with reactor internals.
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070337.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.5
CFR Part: 
CFR Title: 

Content:
aulted 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 assureensure 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 operability is also demonstrated. This appendix is necessaryThe objective of this appendix is to improve consistency and 118 understanding of the basic approach in the selection of load combinations applicable to safety-related systemsthe subject components and structures and to establish acceptable 119 relationships between plant postulated events, plant and system operating conditions, component and component support design, and service stress limits, functional capability, and operability. 120 B. DISCUSSION Current reviewsReviews of both standardized plants and custom plants have indicated 121 the need for additional guidance to reach acceptable design conclusions in the following areas: (1) Relationship between certain plant postulated events, plant and system operating conditions, resulting loads and combinations thereof, and appropriate design and service stress limits for ASME Class 1, 2, and 3 components and component supports, and Class CS core support structures. 122 123 (2) Relationship of component operability assurance, functional capability, and allowable design and service stress limits for ASME Class 1, 2, and components and component supports.3 components and component supports, and