Modelling of radiolysis of reactor cooling water - a comparative study

Computations of the coolant radiolysis in the primary heat transport (PHT) system of the CANDU (Canadian Deuterium Uranium) PWRs by using two reaction mechanisms-hot water radiolysis and supercritical water radiolysis, are presented. The radiolytic product concentrations formed under the conditions of both radiolytic mechanisms in the presence of different amounts of hydrogen in the coolant are compared. The results suggest that the PHT system should react in a more sensitive way to changes in the hydrogen concentration when the mechanism of the supercritical water radiolysis is applied. The consequences of using either mechanism in modelling of the coolant radiolysis are briefly discussed. (author)