Water Coolant Technology and Chemistry for Supercritical Water Cooled Reactors

Abstract

SCWR water chemistry technology is a big challenge for chemistry and material research. The main goal is to minimize corrosion and activity transport in the system and to ensure high purity of coolant – from active core to turbine region. So far experience from PWR and BWR reactors is used as a base for discussions of possible scenarios and options. Critical conditions could be on fuel surfaces due to high temperature and high heat flux on the surface. Also the temperature range in the active core could represent complications to find an optimal chemistry conditions.
Change in the density of SCW through the critical point is accompanied by dramatic changes in chemical properties of water. These changes mean that the ionic solubility, pH, corrosion potential etc. will be distinctly different at the core inlet compared to the outlet and system is mainly influenced by in-core radiolysis. The radiolytic yields and recombination rates in SCW are currently unknown and preliminary studies suggest a markedly different behavior at SCW conditions compared to what would have been predicted from simplistic extrapolations of the behavior encountered in conventional water- cooled.
Discussion is concentrated on different types SCWR concepts and corresponding purification and technological systems ensuring high purity of coolant and minimizing corrosion product and activity transport in primary circuit.