Lifetime assessment of selected components of WWER-440 units

A detailed analysis is made of factors which affect the life of the main components of nuclear power plants with WWER-440 reactors: of the pressure vessel, primary circuit pipes, steam generator and pressurizer. As such factors which are given by the choice of construction materials, dimensions of assemblies, etc., cannot be influenced for existing equipment, attention is centred on operating factors which are given by the loading method, impact of radiation embrittlement, corrosion, aging, fatigue processes, etc., and factors which are given by the possibilities and abilities to return the installation its ability to perform its function. It is stated that so far there is not enough experience and knowledge to be able to assess the possibilities and conditions which will be decisive for extending the life of the main components of nuclear power plants. Information should therefore be consistently collected on the state of the major nuclear power plant assemblies; it will also be necessary to optimally control non-steady state operating processes and to cope with maintenance and repair requirements. (Z.M.). 4 refs