OPR-1000 원자로의 출력증강을 위한 18×18 원통형 핵연료의 열수력적 타당성 평가

The thermal hydraulic analysis of the 18×18 solid fuel assembly has been carried out for the power uprate of OPR-1000. The suggested 18x18 solid fuel assembly has a structural compatibility for reloading to operating PWR reactors of OPR-1000. In the thermal hydraulic analysis, the mixing effect between the neighboring channels has to be carried out in a subchannel analysis. A subchannel analysis code, MATRA has been developed by KAERI. The main parameters for the thermal hydraulic design, such as a pressure drop and DNBR, and the maximum temperature in a fuel pellet have been estimated. The 18×18 solid fuel in the 120% power uprate showed an increased pressure drop and a similar DNBR behavior. The peak temperature in the fuel centerline, however, was slightly higher than that of the 16×16 solid fuel assembly for the normal operation condition. The peak temperature of a fuel pellet in the solid fuel should be seriously considered for increasing power density.