XN9500226 EFFECTS OF TEMPERATURE ON CORROSION FATIGUE CRACK GROWTH OF PRESSURE VESSEL STEELS IN PWR COOLANT D R Tice, I L Bramwell, H Fairbrother and D Worswick AEA Technology, Risley, Warrington, WA3 6AT, United Kingdom Summary Prediction of the rate of propagation of defects in pressure boundary components in light water reactors is necessary in order to demonstrate integrity of the primary circuit during the lifetime of the plant. As a result, there has been extensive work examining the effects of the reactor coolant on corrosion fatigue crack propagation behaviour. The great majority of this work has concentrated on normal plant operating temperature. However, the largest changes in stress (i.e. cyclic loading sequences) occur during plant heat-up or shutdown or other non- isothermal transients. The work described in this paper is aimed at measuring crack propagation rates in A508-III pressure vessel steel exposed to PWR primary water at temperatures between 130 and 290°C. The results indicate that the greatest degree of enhancement occurs at temperatures in the range 150 to 200°C. Under these conditions, there was a marked change in the appearance of the fracture surface, with extensive micro-branching of the crack front and occasional bifurcation of the whole crack path. In contrast, at 290°C, the fracture surface is smoother, similar to that due to inert fatigue. The paper examines the implication of these observations for assessment of pressure vessel integrity. 49 I NEXT PAQE(S) I left BLANK
EFFECTS OF TEMPERATURE ON CORROSION FATIGUE CRACK GROWTH OF PRESSURE VESSEL STEELS IN PWR COOLANT
May 17, 2023
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