Effect of Operating Parameters on RBMK-1000 Fuel-Element Cladding Oxidation

Abstract

The results of research on the corrosion state of the fuel elements of sixteen RBMK-1000 fuel assemblies operating at the Leningrad NPP to burnup 6.1–35.7 MW·days/kg are presented. The dependences of the oxide thickness on the outer surface of cladding on the operating time, fuel burnup, and average power release of FA are presented. It is determined that increasing the power output from 0.9 up to 2.1 MW approximately halves the oxidation rate on the sections between the spacing lattices. For close FA operating parameters, larger oxide thickness was recorded on sections of fuel elements beneath the steel spacing lattices than beneath the zirconium lattices. It is shown that in terms of the conditions for its manifestation and external indicators the additional oxidation arising beneath the steel lattices has the characteristic features of shadow corrosion.