Document: NUREG-0800
Document ID: fb538e14-08a0-4d3f-a974-8170cbfe0b5b
Document Type: srp
Title: ASME CODE CLASS 1, 2, AND 3 COMPONENTS,
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340603.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.3
CFR Part: 
CFR Title: 

Content:
cified by the Code (i.e., level C and D) may not assure the functional capability of components, including their supports, to deliver rated flow and retain dimensional stability. Since the combination of loadings, the selection of the applicable design and service stress limits appropriate to each load combination and the proper consideration of operability is beyond the scope of the Code; and the treatment of functional capability, including collapse and deflection limits, is not adequately treated by the Code for all situations, such factors must be evaluated by designers and appropriate information developed for inclusion in the Design Specification or other referenced documents. Applicants require guidance with regard to the selection of acceptable design and service stress limits associated with various loadings and combinations thereof, resulting from plant and system operating conditions and design basis events, natural phenomena, and site-related hazards. The relationship and application of the terms "design conditions," "plant operating conditions," "system operating conditions," and the formerly used term "component operating conditions," now characterized by four levels of service stress limits, have not been clearly understood by applicants and their subcontractors. 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 assure 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