Materials Challenges of the New Nuclear Power Plant in Hungary

Having the experience accumulated during close to twenty thousand reactor years worldwide one may say that enough knowledge is available on the behavior of nuclear structural materials. In recent years however new questions emerge in close association with the long-term operation of nuclear power plants. The questions are in relation with both the operating and the future plants. Hungary operates four Russian designed VVER-440 nuclear units, and currently, two VVERs are under construction. The new, VVER-1200 type reactors represent the generation 3+ which is the latest and the safest version of the world's reactor fleet in operation. Service life of VVER-1200 reactors is 60 years, and operation beyond this term is foreseen. The structural materials of the main and usually non replaceable pressurized components such as reactor pressure vessel, steam generator and so on have to resist load and environment during the long operation period to ensure the components' structural integrity. It is right to say that the long-term, safe operation of the current and future reactors is ultimately governed by the performance of the structural materials in the mechanical technological systems. After introduction of the evolution process of the VVER structural materials performance the article reviews the major loading and environmental parameters of the operation and the ageing effects induced by the operation. Then the most important materials aspects and challenges are presented and discussed.