Component testing at the HDR-facility for validating the calculation procedures and the transferability of test results from specimen to component

Abstract

The HDR pressure vessel and various pipework systems were loaded by static and transient loads, both thermally and mechanically, until crack growth or breakoff occurred. Parallel to component testing laboratory-scale tests were carried out on specimens as well as calculations in support of the experiments. The results of measurements and calculations were compared. Incipient crack in the cladding of the reactor pressure vessel under cyclic thermoshock loading occurred after a number of load cycles which roughly correspond to those in the ASME design curve. For pipework components, in that case incipient crack in an elbow, good agreement was found between specimens and components. Crack propagation under cyclic thermoshock loading in the RPV wall at aggravated corrosive conditions is greatly overestimated in the calculation. The major causes of the deviation are the flow rate and the chemistry of the medium and differencies in the stress conditions of specimen and component. For pipework tested at constant temperature the transferability from specimen to component was found to be relatively good. The crack propagation had been only slightly overestimated in that case. The question of stable crack growth in the thermoshock tests performed at the RPV will be answered after fractographic analysis of the rupture surfaces. The leak-beforebreak behavior of pipework made from ductile material was confirmed in two tests performed under cyclic bending load and in two tests under seismic loading conditions.