Results and evaluations of irradiation surveillance programmes of lightwater reactors in Germany

Nineteen nuclear power plants are in operation in Germany. The shift of the "ductile to brittle transition temperature" of the core belt materials, induced by neutron irradiation, was calculated as DeltaT(41) in the design-phase of each power station. Additionally irradiation surveillance programmes for all plants were performed during operation. Most of the irradiation surveillance programmes are finished and the results are available. The paper presents some results of irradiation surveillance programmes of German Nuclear Power Stations and the comparison of the neutron-induced shift of the Charpy-V-transition curve measured and predicted according to the German KTA and other safety standards. For most of the materials the prediction according to different nuclear safety codes and procedures for calculating the irradiation reaction is in good agreement with the measured values, but some of them show a different behaviour. This payer also offers some new aspects for explanation of these deviations taking into account the chemical composition and the irradiation-induced strain-hardening. (C) 2000 Elsevier Science Ltd. All rights reserved.