Specific problems such as the embrittlement of the WER reactors or the integrity evaluation of the Yankee Rowe reactor pressure vessel, show the necessity of continuing in the understanding of the mechanisms responsible for the embrittlement. Besides, in order to increase the safety and performance of the nuclear power plants, it is important to optimize the surveillance programmes and develop the mitigation techniques of the damage caused by neutron radiation.

Proceedings of the 8th ASTM-Euratom Symposium, held in Vail, Colorado, Aug.-Sept. 1993, to provide a forum for experts to discuss their latest results under the broad theme of dosimetry for the correlation of radiation effects. Preceded by a summary of the keynote presentations and followed by summa

Research on irradiation embrittlement in modern pressure vessel steels was initiated at the French Atomic Energy Commission ten years ago. During this period many steels and welds were irradiated in the Triton and Siloe reactors; research was undertaken both independently and within the framework of research programs coordinated by the International Atomic Energy Agency.

The present research program on irradiation embrittlement and annealing of reactor pressure vessel (RPV) steels in Switzerland is carried out at the Paul Scherrer Institute for Reactor Research. The particular program structure and its relation to the concept for an improved surveillance program is described.

Radiation embrittlement and its mitigation by annealing of VVER-440 reactor pressure vessel steels are studied. The Russian regulatory approach for prediction of radiation embrittlement of VVER-440 steels is considered. Results of an investigation of materials cut out of operating nuclear power plants are discussed. Different models of re-irradiation embrittlement are compared. A new model for assessment of embrittlement under re-irradiation is developed.