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:
with the J3 values in Step c. See Figure A-2 in Appendix A for anexample. The time at which the J-R value is just equal to the J, determines the critical condition for evaluating Equation 1. g. At the timedetennined in Step f, evaluate Equation 2 to verify the stability of predicted flaw growth. 2.2.2 Evaluation of Flaw Stability Flaw stability is evaluated by a direct application of the flaw stability criterion given by Equation 4. The applied J integral is calculated for a series of flaw depths corresponding to increasing amounts of ductile flaw growth. The applied pressure, p, is set equal to the peak pressure for the Service Level C transient under consideration with a safety factor, SF, equal to 1.0. The applied J-integral for Service Level C conditions may be calculated using Equations I I through 15. Each pair of the applied J-integral and flaw depth is plotted on a crack driving force diagram to produce the applied J-integral curve as illustrated in Figure 1. The materiars J-R curve also is plotted on the crack driving force diagram and intersects the abscissa at the initial flaw depth, a,. Flaw stability at a given applied load is demonstrated if the slope of the applied J integral curve is less than the slope of the material's J-R curve at the equilibrium point on the J-R curve where the two curves intersect. 2.3 Level D Condition The acceptance criteria discussed in Regulatory Position I for Level D Service Conditions involve only the stability of K the postulated flaws. Additionally, the stable flaw depth must not exceed 75% of the vessel wall thickness, and the remain ing ligament must be safe from the tensile instability. Stability of ductile crack extension is demonstrated for Service Level D in the same manner used for Service Level C. However, the material properties should represent only the best estimate (i.e, mean value) of the J-R curve for the vessel material under evaluation. Tensile stability of the remaining ligament is conserva tively