Experimental measurements and numerical simulations to evaluate the electrode kinetics for 316 stainless steel under PWR-relevant conditions

The local environment in an occluded region of a pressurized water reactor (PWR) depends on its geometry, its access to the bulk and the nature of the electrode kinetics at the metal surfaces. In PWR-relevant, oxygen-free, boric acid–lithium hydroxide solutions the dominant anodic and cathodic electrode reactions are found to be hydrogen oxidation and water reduction, respectively. The hydrogen oxidation reaction kinetics have been quantified using potentiostatic measurements – at 300 C, under various dissolved hydrogen concentrations, for 1000 ppmB and 2 ppmLi. The reaction kinetics have been verified by modelling of a crevice experiment performed in an autoclave at 300 C for 1000 ppmB, 2 ppmLi and 25 STP ccH2/kg.