Approaches for Estimation of Radiation Damage Parameters on VVER Equipment and Their Implementation during Monitoring Procedure
SourceThe problem of ensuring the integrity of VVER type reactor equipment is now most significant in justifying the safety of nuclear power plant units and the extension of their service lifetime to 60 years and more. This issue primarily concerns old NPP power units with VVER-440s and VVER-1000s. The justification of VVER equipment integrity depends on the reliability of estimating the degree of equipment damage. One of the mandatory requirements, providing the reliability of such estimation and also the evaluation of VVER equipment lifetime, is the monitoring of equipment radiation loading parameters. Relative to this requirement is the challenge of justifying the normative parameters used for estimating reactor pressure vessel metal embrittlement as the fluence and fluence rate of fast neutrons with energies above 0.5 MeV. Compliance with these requirements is analyzed during regular monitoring of radiation load parameters, which is performed by the Scientific and Engineering Centre for Nuclear and Radiation Safety for all Russian NPP. As a result of this activity, the Scientific and Engineering Centre for Nuclear and Radiation Safety has recently elaborated on new approaches aimed at monitoring the radiation load of all Russian VVER equipment. This paper describes these approaches and explains the means of their implementation during monitoring procedures.