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:
ding orientation. When the Charpy upper-shelf energy of any weld material is less than 50 ft-lb, postulate an interior semi-elliptic surface flaw with the major axis oriented along the weld of concern and the flaw plane oriented in the radial direction. Consider postulated surface flaws with depths up to one-tenth the base metal wall thickness, plus the clad thick ness, but with total depth not to exceed 1.0 inch (2.54 cm) and with an aspect ratio of 6-to-I surface length to flaw depth. A smaller maximum flaw depth may be used on an individual case basis if justified. For these evaluations, the postulated flaw must be stable under ductile crack growth as given by Equation 5: at (5) (with load held constant) Jw1'ppWia = J.mWAial where J.3P is calculated for the postulated flaw under the governing Service Level D condition, with a safety factor of 1.0 on the applied loading. Additionally, the flaw depth, including stable tring, should not be greater than 75% of the vessel wall thickness, and the remaining ligament should be safe from tensile instability. The material's J-integral fracture resistance should reflect a best estimate, Le., the mean value, of the data representative of the vessel material under evaluation. The J-integral resistance versus crack growth, J-R curve, is discussed in Regulatory Position 3 of this guide. Methods for determining the appropriate service level conditions are discussed in Regulatory Position 4 of this guide. 2. ANALYSIS METHODS The analysis methods described in this guide are acceptable to the NRC staff for evaluating the criteria de scribed above. Other methods may be used ifjustifled on a case-by-case basis. 2.1 Level A and B Conditions The acceptance criteria discussed in Regulatory Position 1.1 for Level A and B conditions involve a comparison of the applied J-integral to the material's J-integral fracture resis tanc at a ductile flaw extension of 0.1 inch and a determina tion that this flaw would be stable under the applied