Water chemistry for supercritical water-cooled reactor

The aim of this article is to introduce the water chemistry requirements for Supercritical Water-cooled Reactor (SCWR). In the SCWR technology takes place a conversion of subcritical water into supercritical water (SCW). This conversion represents a change of many medium properties. The final effect of the changes on the power plants system is not enough explored yet. As a coolant of nuclear units, supercritical water brings in the issue of water chemistry new topics that need to be followed. These topics include: high corrosion rate of structural materials, precipitation of dissolved impurities and corrosion products on the fuel cladding, limitation of heat transfer from the fuel to the medium and local overheating of the fuel, erosion damage of the turbine due to the activated corrosion products transport, with this transport related increase of activity throughout the primary circuit representing a danger to staff power, the water radiolysis and dissolution of organic substances, their reaction with heteroatoms and thereby caused formation of salt deposits. From these risks point of view is very important the purity of the coolant. The assumption is that the water chemistry of SuperCritical Water-cooled Reactor will be based on the water chemistry of present Boiling Water Reactors (BWRs).