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:
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 demonstrated if Equation 16 is satisfied. Ofa (16) Where, from Reference 13, for a semi-elliptical flaw, a** - [a*(l - (1 + 2c'A 2)4 )] / (1 - (a*/A){1 + 2c"A2)-] 3. MATERIAL PROPERTIES The statistical analyses reported in Reference 10 addressed a broad range of materials and conditions For the purposes of this guide, the NRC staff has concluded that only the ASTM E 1152-87 (Ref 9) definition of the J-integral fracture resistance curve should be used. This determination requires that a test specimen's net thickness, B%, be specified. Smaller specimens typically produce more conservative (lower) J-R curves than larger specimens. However, larger specimens are needed to provide large amounts of crack growth needed in evaluating certain stability criteria described in Regulatory Position 2 of this regulatory guide. The NRC staff recommends the test specimen's net-section thickness, B, to be 1.0 inches (2.54 cm) for determining the J-integral resistance curve using the methods specified in Regulatory Position 3. This is a reasonable compromise and slightly simplifies the equations for the material J-ft curve. The neutron fluence attenuation at any depth in the vessel wall (such as near the crack tip) should be determined using Regulatory Guide 1.99 (Ref 14). This guide provides methods for determining the I integral fracture resistance of three classes of materials: welds Sm factured with Linde 80 welding flux, generic welds used in fabricating reactor pressure vessels, and plate materials (low and high toughness). The J-R curves for plant-specific materials may be used if justified on a case-by-case basi. Otherwise, the material's J-integral fracture resistance may be determined from Equation 17, developed in Reference 10: J4=(0) {C)(Aa) 0exp[C3 (Aap])C 4 \1 (17) 1.161-8