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, in duced by neutron irradiation, was calculated as DeltaT(41) in the design-ph ase of each power station. Additionally irradiation surveillance programmes for all plants were performed during operation. Most of the irradiation su rveillance programmes are finished and the results are available. The paper presents some results of irradiation surveillance programmes of G erman Nuclear Power Stations and the comparison of the neutron-induced shif t 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 saf ety codes and procedures for calculating the irradiation reaction is in goo d agreement with the measured values, but some of them show a different beh aviour. This payer also offers some new aspects for explanation of these de viations taking into account the chemical composition and the irradiation-i nduced strain-hardening. (C) 2000 Elsevier Science Ltd. All rights reserved .