Feasibility Study of Double-Flat-Core Type HCPWR for Reactivity Initiated Accidents.

A conceptual design of a double-flat-core type high conversion pressurized water reactor (HCPWR) has been developed at the Japan Atomic Energy Research Institute to improve fuel utilization. In thermal-hydraulic feasibility studies of the proposed concept, major six events such as large and small break LOCAs have been analyzed with the best estimate code REFLA/TRAC. This paper describes the results of control rod ejection accident analyses as a part of the series of analyses. The calculations were performed according to the licensing analysis on current PWRs. The calculated results showed that the proposed concept had larger safety margines than current PWRs. Therefore, the proposed concept is considered to be feasible from a view point of safety analysis of control rod cruster ejection accident. It is seen that the large safety margine of the proposed concept is originated from smaller excess reactivity, smaller maximum linear heat generation rate and smaller rod worth per a control rod than those of current PWRs.