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:
s the J-integral value calculated for the postu lated flaw under pressure and thermal loading where the assumed pressure is 1.15 times the maximum accumulation pressure, with thermal loading using the plant-specific heatup and cooldown conditions. The parameter J,, is the J-integral characteristic of the material's resistance to ductile tearing Q...), as denoted by a J-R curve test, at a crack extension of 0.1 inch. 1.1.2 The flaw must be stable under ductile crack growth as given by Equation 2: < C'V 8a a a (with load held constant) (2) at = p~fod = lal where J,•. is calculated for the postulated flaw under pressure and thermal loading for all service level A and B conditions where the assumed pressure is 1.25 times the maximum accumulation pressure, with thermal loading, as defined above. The material's J-integral fracture resistance should represent a conservative estimate of the data for the vessel material under evaluation (i.e., mean - 2 standard deviations). Methods for determining the J-integral fracture resistance, J-R curve, are 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. 1.2 Level C Condition When the Charpy upper-shelf energy of the base metal is less than 50 ft-lb, postulate both axial and circumferential interior flaws and use the toughness properties for the corre spending orientation. When the Charpy upper-shelf energy of any weld material is less than 50 ft-lb, postulate an interior surface flaw with its 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 thickness, but with te 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-cas basis if justified. For