The overall objective of this project is to evaluate the feasibility of supercritical light water cooledreactors for electric power production. The use of light water at supercritical pressures as the coolant in anuclear reactor offers the potential for considerable plant simplification and consequent capital and O & Mcost reduction compared with current light water reactor (LWR) designs. Also, given the thermodynamicconditions of the coolant at the core outlet (i.e. temperature and pressure beyond the water critical point), very high thermal efficiencies for the power conversion cycle are possible (i.e. up to about 45%). Because no change of phase occurs in the core, the need for steam separators and dryers as well as forBWR-type re-circulation pumps is eliminated, which, for a given reactor power, results in a substantiallyshorter reactor vessel and smaller containment building than the current BWRs. Furthermore, in a directcycle the steam generators are not needed. If no additional moderator is added to the fuel rod lattice, it ispossible to attain fast neutron energy spectrum conditions in a supercritical water-cooled reactor (SCWR). This type of core can make use of either fertile or fertile-free fuel and retain a hard spectrum to effectivelyburn plutonium and minor actinides from LWR spent fuel while efficiently generating electricity. Onecan also add moderation and design a thermal spectrum SCWR that can also burn actinides. The projectis organized into three tasks.