Hydrogen and Oxygen Behaviour in PWR Primary Coolant

摘要

Hydrogen is added to PWRs to ensure that reducing conditions exist in the primary coolant. The normally accepted minimum is ～15 cc (STP) kg~(-1), but recent data indicate that the true value at ～300°C is <5 cc (STP) kg~(-1). This paper uses computer modelling to examine how the "critical hydrogen concentration", or the CHC, changes with temperature, type of radiation, dose rate and boron concentration. The results show that the main factor is the temperature, with increasing temperature reducing the CHC required to suppress radiolysis, as well as reducing steady-state oxidant concentrations. The paper also examines the effect of oxygen ingress into the primary circuit.