Document: NRC Regulatory Guide
Document ID: 2704425a-c58a-45c4-93ab-8761721c3e7a
Document Type: regulatory_guide
Title: Evaluation of Reactor Pressure Vessels with Charpy Upper-Shelf Energy Less Than 50 Ft-Lb
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740038.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.161
CFR Part: 
CFR Title: 

Content:
e necessary to demonstrate compliance with Standard Review Plan 3.9.3 (Ref. 11) should be used. When Ihis transient list isnot available or is incomplete, the most complete list oftransicnts for these service levels that is available for similar plant designs should be used. Typi cally, the most complet list of transients would be for the later-vintage plants from a particular vendor. This list should be reviewed, and the limiting transients for the reactor vessel being analyzed should be defined. Once the transients are defined, system-levl thermal-hydraulic analyses should be performed to determine the limiting presmre-temperature time history for each transient being considered. This history provides the input to the analyses described in this guide. 4.2 Bounding Transients When the plant-specific transients are not available or when developing or updating the pressure-temperature-time histoy would be an undue burden, a conservative "bounding" pressure-tenmprature-time history may be used. This history shxmld anticipate a pressure equal to the shut-off head for the high-pressure injection system and a cooldown rate of 400OF per hour for Service Level C and 6001' per hour for Service Level D. These values are based on the NRC staffs experi ence in performing the bounding analyses (for examples, see Appendix A of this regulatory guide and Reference 4). Altematives to these cooldown rates may be used ifjustified by the plant-specific safety-injection flows and temperatures. D. IMPLEMENTATION TIhe purpose of this section is to provide information to applicants and licensees regarding the NRC staffs plans for using this regulatory guide. Except in those cases in which an applicant or licensee proposes an acceptable alternative method for complying with specified portions of the Commission's regulations, the methods descnled in this guide reflecting public comments will be used by tlhe NRC staff in the evaluation of applications fornew licenses and for evaluating