Problems of operating life extension for first generation WWER type reactors

The program of researches aimed to substantiate the possibility of extending service life as for WWER-440 reactor vessels so for reactor internals (RI) is reported. Provision is made for the elaboration of standardized documentation providing estimates of an acceptable service life of reactor vessels on the basis of small-size specimen testing results. The evaluation of fracture toughness temperature dependence is proposed to be obtained after irradiation up to the fluence exceeding the design value and corresponding to 10 and 16 years above the rates service life. Static and cyclic strengths of reactor vessels will be estimated from calculation results for a cylindrical part and a nozzle area with welded joints and a flange. The list of works on estimating RI state and substantiating the possibility of their life extension includes the following: the estimation of radiation swelling, static and cyclic strength variations, a change in steel 08Kh18N10T resistance to brittle fracture under neutron fluence up to 1 x 1023 neutr cm-2 in the temperature range of 270-350 deg C; the estimation of dimensional variations in RI; the estimation of service condition effects RI on operational capability