Impacts of Extended Used Fuel Storage on Performance of Fuel Cycles with Continuous Recycle of U/Pu or U/TRU

摘要

An Evaluation and Screening (E&S) study of nuclear fuel cycle options conducted for the U.S. Department of Energy, Office of Nuclear Energy (DOE-NE) identified four most promising groups out of 40 Evaluation Groups (EGs). This work investigated the effect of using extended storage on the fuel cycle performance of these groups for two nuclear capacity growth rates: 0% and 1% annual growth. For the 0% annual nuclear capacity growth, the effect on fuel cycle performance is mainly due to nuclide decay, especially the Pu-241, Pu-238, and Cm-244 decay during storage. The results showed that the effect on most of the fuel cycle metrics considered such as the volume of Low-Level Waste, land use, water use, carbon emission, radiological exposure, etc., due to extended storage is small. Only the High-Level Waste activity changed by ＞10% when storage time was extended arbitrarily from 7 years to 102 years. The decay heat and activity of the fresh and discharged fuel decrease with increasing post-irradiation storage time, but they may increase, decrease, or stay constant with increasing post-separation storage time depending on their major isotopic contributors (Pu-238, Pu-241, Cm-244, or fission products). For the 1% annual nuclear capacity growth, the availability of Pu resource becomes the main constraint on the extended storage and the main cause for the changes in fuel cycle performance. In this case, additional Pu is required to sustain the energy growth. This could be achieved by using more blanket fuel loading in fast reactors, which reduces the average fuel burnup. Thus, more heavy metal per energy generated needs to be fabricated and reprocessed for longer storage time, which would increase the Low Level Waste volume, High Level Waste mass, and carbon emission significantly.