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:
nd reptwentation (mean - 2 standard deviations) of the J-R curve should be used. For analyses addressing Service Level D, the mean value of the J-R curve should be usecd Additional J-R curve test data for the low-toughness A302B plate material are presently being generated. Regula tory guidance will be updated, ifjustified, based on the results obtained from the test data collected for J-R curve in low toughness plate material. 4. TRANSIENT SELECTION Selection of the limiting transients for Service Levels C and D is a key aspect of evaluating the integrity of reactor pressure vessels that contain materials with Charpy upper shelf energy less than 50 fl-lb. Generally, Service Levels A and B are limiting. However, there may be plant-specific consicerations that make Service Levels C or D controlling for ductile fracture. To provide reasonable assurance that the limiting service loading conditions have been identified, either oftwo approaches may be used: a plant-specific transient evaluation or a generic bounding analysis. It should be noted that plants may be grouped and limiting transients for these groups may be determined. The plant-specific transient evaluation is the preferred approach. However, since some licensees may not have the specific transient infoafnaion needed for this analysis, a conservative "bounding" anasis may be performed for each service level. Specific guidance for each of these approaches is provided below. As described in the Discussion section of this guide, ductile tearing is the dominant fraure process in the upper shelf region, and the possibility of mode-conversion to cleavage (brittle) fracture is not considered in this regulatory guide. The analyses using these bounding transients need only address the transient from its beginning to the time at which the metal at the tip of the flaw being analyzed reaches a tm rau equivalent to the adjusted RT. plus 500F. In this regulatory guide, an adusted RTmr plus 50WF (which typically represents