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:
transient = 10 0Fihr Base Metal Thermo-Elastic Properties: Modulus of elasticity, E = 27E3 ksi; Poisson's ratio, v = 0.3 Yield stress, a, - 80 ksi; Ultimate stmre, o.= 90 ksi Flow stress, ot = 85 ksi; Fluid heat transfr cocf- =1000 BTU[hr-O-'F Theral diusivity = 0.98 inninte; (E&.,Y(l - v) = 0.305kiPF Cladding Thermo-Elastic Properties: Thermal expansion coefficient, a = 9.1E-6PF; Poisson's ratio, v = 0.3 Modulus of elasticity, E - 27E3 ksi; Thermal conductivity = 10 BTUihr-fl-¶F Stress-free temperature ofcladding = 5500F; Initial operating temp. = 550OF The VISA-iI code,. with modifications for printing KI, Ka, and KI for 6-to-I aspect ratio flaws, was used to perform analyses for determining transient theamo-mcchanical stresses and temperature gradients across vessel wall thickness. An sxdal flaw with an aspect ratio of 6 to I was postulated to xist in the vessel internal wall. To account for the effect of crack-face pressure on stress intensity factor solutions in VISA-Il, the accumulation pressure was adjusted to be equal to [p.t'.{ l + RPA')}/, 3.02 ksi. At a fixed crack depth of (0.25t'-O. 1) inch, the tempcrature history prediction is shown in Figre A-I for a transient with a constant cooldown rate of IO0•ihr. With a factor of safety, SF, of 1.15 on accumulation pressure for Equation I of this guide, the applied J-integral history at a crack depth of (0.25t'+ 0.1) inch for mechanical and thermal stresses, including the cladding effects, is shown in Figure A-2. The applied J-integna reaches the peak steady-state value of 486 in.-Ib/imn in about 150 minutes. Also shown in Figure A-2 are the J-R curves for generic welds (Equations 17, 24-25) at three Charpy V-notch uppcr-sheffencrgy (CVN) values. These J-R curves were drawn for a crack extnsion, As, of 0.1 inch and for the temperature history, in Figure A-I, at a crack depth of (0.25t'-O.1) inch A study ofFigure A-2 shows an interesting trend that the crack initiation is predicted to take place at about 45