First core design and in-core fuel management of PWR with thorium high enriched uranium

For the Th-HEU fuel cycle, the calculations had been performed for a standard 1300 MWe PWR of KWU. Fuel assemblies of type 16x16-20 were used. The two group cross section libraries were calculated with Th-FASER. The core calculations were performed in octant geometry using the Two-Dimensional depletion code MEDIUM-2. The study starts with an initial core composition of 2.9, 3.6 and 4.2 w/o U-235 in thorium. Once-through and mixed-recycling was investigated for 3 batch and 4 batch cores. In mixed-recycling all fuel assemblies of reload batch consist of the same mixture of reprocessed uranium and HEU. For the 3 batch once-through cycle a reload enrichment of 4.2 w/o U-235 was used. This is equivalent to an enrichment of 4.8 w/o U-235 for the 4 batch core. The mixed recycling started with the begin of cycle 4. A storage of 2 years was assumed. The reload enrichment was 3.9 w/o U-fiss for the 3 batch core and 4.5 w/o U-fiss for the 4 batch core. The different types of cycles lead to a very similar core behaviour. A cycle length of 300 fpd is reached. The calculated reactivity coefficients and reactivity balances ensure a safe reactor operation. (author). 1 ref., 15 figs, 9 tabs