3D-FE-CALCULATIONS OF A PRESSURE-VESSEL UNDER THERMAL-SHOCK LOADING

After concluding the cyclic thermal shock tests on the nozzle A2 and in the cylindrical area of the HDR-RPV, several institutions have conduced preliminary calculations on the long-term thermal shock test project using finite element method. These investigated the behaviour of the nozzle and the cylinder wall, each of which possessed a single crack. The comparison of the results (CMOD, J-integral) with particular reference to the cylinder wall, resulted in great differences partly due to the different discretisations, boundary conditions and crack geometries. The main influence, however, came from the different assumed material parameters. With the calculated J-integral values for the cylinder wall a stable crack propagation of about 1 mm was predicted. The crack in the cylinder wall does not reach the maximum opening by the test end. In contrast, the calculation on the nozzle shown a rapid opening of the crack at the beginning of the test with a subsequent gradual closing. © 1990.