Abstract
The minor actinides in spent fuels dominate long-term hazard radioactive waste. In this study, we evaluated the minor actinides reduction in minor actinides multiple recycling fuel cycle compared with minor actinides non-recycling. SAS2H control module in SCALE 4.4a code system was used to calculate fuel depletion and actinide transmutation. The LWR and LMFBR fuel cycle were investigated respectively.For the LWR fuel cycle it was assumed that the fresh fuel consists of uranium oxide with a 3.2% enrichment of 235U and the burnup is 33 GWd/tHM. For the LMFBR fuel cycle the fresh fuel was assumed to be the oxide fuel consisting of 12.4% of Pu, which is from thirteen of the LWR spent fuels, and 87.6% depleted uranium and a burnup of 100 GWd/tHM was adopted. After the completion of the burnup and cooling, the minor actinides in the spent fuel were added in the fresh fuel and stored a while for recycling. It was assumed that the sum of cooling time and storage time are 5 years for LWR and 10 years for LMFBR.For LWR, the minor actinides reduction in multiple recycling fuel cycle at 10th recycling are 20% compared with LWR once-through fuel cycle. For LMFBR the minor actinides reduction in minor actinides multiple recycling fuel cycles at 20th recycling are 90% compared with minor actinides non-recycling fuel cycle. For radiation shielding safety issue, the source intensity and dose equivalent rate of fresh fuels in minor actinides recycling LMFBR fuel cycle were also evaluated. It was found that after a few recycling the neutron intensity of the fresh fuel is ~3.3×108 neutrons/s per assembly and the gamma-ray source intensity is ~2.3×1013 gamma-rays/s per assembly. Furthermore, the neutron and gamma dose equivalent rate at 1 m distance from the fresh fuels are ~3.8×103 μSv/hr and ~8.4×104 μSv/hr, respectively. Therefore, shielding problems must be taken into account for fuel fabrication, transportation, and handling.