ADVANCED METHODS FOR ANALYSIS OF THE REACTIVITY INSERTION ACCIDENT FOR PRESSURIZED WATER REACTORS

摘要

In a joint EDF/Westinghouse program, three-dimensional (3-D) neutron kinetics calculations have been performed to determine the fuel duty (fuel temperature transient and peak fuel enthalpy) reached in a control rod ejection accident from various power levels at end of life. The program was initiated in response to the recent issue on the behavior of high burnup fuel in a fast reactivity insertion accident (RIA). The purpose of the program was to support the EDF analysis effort on this issue. The initial power levels chosen for the analysis were 0.1%, 10%, 35% and 100% of rated thermal power. End of cycle conditions were chosen for the analysis since if the fuel failure criterion were revised, it would be expected to decrease with burnup. The zero power case was initially selected as a "benchmark" case, and the calculational results using the Westinghouse SPNOVA code were compared to both an analytic solution of the neutron kinetics equations, as well as to the results obtained by EDF using their transient 3-D computer code COCCINELLE. The "at-power" cases (initial power levels of 10%, 35% and 100% of nominal) were selected to determine the effect of power level on the transient fuel duty. This paper addresses the results of the program, and in addition, presents a theoretical explanation for the 3-D benefit noted in the analysis of the at-power cases.