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:
erial Thickness, t = t, - 6.0 in.; Cladding thickness, t., = 0, M - 20 Flaw orientation - Axial, in plate material; Flaw aspect ratio - 6 to I The VISA-il code was used to determine thermal stress and temperature history for the Level C transient specified in the problem. It was found that at time tin =16 minutes, peak thermal stresses occur. The corresponding peak thermal stress intensity factor as a function of crack depth to vessel thickness ratio, alt, of semi-elliptical flaws is given as: KI, = [I 2.243+227.94(at)-972.71 (aht)4+1785.2(a/t)3-1249.3(at)4] ksi"in., with 0.05 < a/t < 0.5 A-2 Therefore, at a = I inch, K -= 27.9 ksi-"in. At an internal pressure, p = I ksi, the pressure-induced K -= 37.0 ksiWin. If the pressure, p, is increased, at a pressur of4.55 ksi, the J-applied at a = (0.1 t + tL + O. I) inch becomes equal to the material's J-R curve as shown in Figure A-5, which will mark an "initiation" of ductile flaw growh The temperature at the crack tip (a-= 0.1t + t.) for time tmi= 16 minutes is 4050F. If the pressure, p, is further increased (see Figure A-5), it can be seen that at a pressure p = 4.75 ksi the crack growth has become unstable. The slope of the J-applied curve is now greater than the slope of the materials J-R curve. Example 4 (Thermal K1t for Prescribed Levels C and D Leading, PWR Vessel) For a PWR vessel, thermal K3 values are determined for a few prescribed cooldown rate (CR) transients. The geometric and material properties are iven as: Vessel Geometry and Loading Conditions: Vessel internal radius, Rý = 86.875 in.; A-533B plate material with cladding Base metal thickness, t = tm - 8.625 in.; Cladding thickness, t. = 5/16 in. Total thickness, t' = (thj + W -98.9375 in.; Ratio, W/t') = 9.72 Thermal cooldown rate, CR = 100"Fihr to 600"Fihr (constant, for each analysis) Inner wall temperature, Tk .(R - = 550'F; TsJR = R) = 150F Base Metal Thermo-Elastic Properties: Modulus of elasticity, E = 27E3 ksi; Poisson's ratio, v = 0.3 Fluid-film