Supercritical water-cooled pressure channel nuclear reactors. Review and status

Concepts of nuclear cooled with water at supercritical pressures were studied as early as the 1950s and 1960s in the USA and Russia. After a 30-year break, the idea of developing nuclear reactors cooled with supercritical water (SCW) became attractive again as the ultimate development path for water-cooling. The main objectives of using SCW in nuclear reactors are 1) to increase the efficiency of modern nuclear power plants (NPPs) from 33 - 35% to about 40 - 45%, and 2) to decrease capital and operational costs and hence decrease electrical energy costs (<<$1000 US/kW). SCW NPPs will have much higher operating parameters compared to modern NPPs (pressure about 25 MPa and outlet temperature up to 625degC), and a simplified flow circuit, in which steam generators, steam separators, steam dryers, etc., can be eliminated. Also, higher SCW temperatures allow direct thermo-chemical production of hydrogen at low cost, due to increased reaction rates. There are two major SCW nuclear reactor concepts under development right now: pressure-vessel concept and pressure-channel concept. Mordern concepts of pressure-channel reactor cooled with SCW are only presented in this paper. These concepts include the SCW CANDU (CANada Deuterium Uranium is a registered trademark of AECL) nuclear reactor concept (Canada) and three concepts developed by RDIPE (Russia). Also, heat-transfer enhancement in tubes and bundles are discussed. The main conclusion is that development of SCW pressure-channel nuclear reactors is feasible and significant benefits can be expected. (author)