Improving the safety of WWER nuclear power plants: Focus on technical assistance in Central and Eastern Europe

Energy balance in Central and Eastern Europe is based to a substantial degree on the use of nuclear energy. Nuclear's share of electricity production stands at about 20% in the Czech Republic, 25% in Ukraine, 32% in Bulgaria, 46% in Hungary, and 49% in the Slovak Republic. Reliable operation of nuclear power plants has been essential for the economic development of these countries. Nuclear plants based upon Soviet technology, specifically pressurized-water reactors (PWRs) of the type known as WWERs, are dominant in Central and Eastern European countries. From the start, the approach to nuclear safety has been different for these plants, when compared with approaches for Westerndesigned PWRs. This resulted, in fact, in serious shortcomings of WWERs when compared with international practices. There was and remains a clear need for transfer of knowledge, particularly in the field of nuclear safety, to facilitate access to information on PWRs and related infrastructures. These needs extend to modern tools of safety assessment; quality assurance programmes; highly computerized instrumentation and control systems; and the use of robotics for inservice inspection, for example. However, the situation should not be generalized. It strongly depends on the specific model of the nuclear power plant. These models start with the old WWER-440/230 (operating in Bulgaria, Slovak Republic and Ukraine), go to the more advanced WWER-440/213 (operating in the Czech Republic, Slovak Republic, Hun-