Predicted Water Chemistry in the Primary Coolant Circuit of a Supercritical Water Reactor

AbstractAmong the six types of Generation IV reactors, the supercritical water reactor (SCWR) is the only one that adopts light water as the reactor coolant. Different from the boiling, two-phase coolant in the core of a traditional boiling water reactor (BWR), the coolant in an SCWR would remain in one phase throughout the entire primary coolant circuit (PCC) due to its much higher operating temperature (>374°C) and pressure (>22.1 MPa). For a conventional BWR, the coolant is relatively oxidizing due to the presence of hydrogen peroxide and oxygen, directly or indirectly produced via water radiolysis. This outcome eventually leads to degradation of structural materials, primarily stress corrosion cracking. In an SCWR, the solubility of oxygen in the reactor coolant is extremely high. In the absence of the gas stripping effect in a single-phase coolant, worse degradation phenomena are expected to appear in the structural and core components. To ensure proper designs of the structural components and suitab...