Structural analysis of electrosleeved tubes under severe accident transients

A flow stress model was developed for predicting failure of electrosleeved PWR steam generator tubing under severe accident transients. The electrosle eve, which is nanocrystalline pure nickel, loses its strength at temperatur es greater than 400 degreesC during severe accidents because of grain growt h. A grain growth model and the Hall-Petch relationship were used to calcul ate the loss of flow stress as a function of time and temperature during th e accident. Available tensile test data, as well as high-temperature failur e tests, on notched electrosleeved tube specimens were used to derive the b asic parameters of the failure model. The model was used to predict the fai lure temperatures of electrosleeved tubes with throughwall and part-through wall axial cracks in the parent tube during a postulated severe accident tr ansient. (C) 2001 Elsevier Science B.V. All rights reserved.