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Preliminary Economic Evaluation of Thorium-Based Fuels in PWRs

M. H. Du Toit, A. C. Cilliers

Nuclear Technology / Volume 187 / Number 3 / September 2014 / Pages 260-269

Technical Paper / Fuel Cycle and Management /

Many studies have proven that thorium-based fuel cycles are more expensive than current uranium fuel cycles, which is confirmed in this paper as well. This research, however, goes beyond the conventional nuclear plant refueling cycle, aiming to optimize the refueling cycle in line with specific advantages realized from the thorium-based refueling cycle. These benefits are the good thermal neutronic characteristics of fertile 232Th and fissile 233U, resulting in longer refueling cycles, higher capacity factors, and reduced volumes of spent fuel. This paper focuses on once-through, homogeneously mixed, thorium-uranium fuel cycles and explores the economic advantages to introducing thorium as a fertile component in pressurized water reactor fuels as compared to once-through conventional uranium-only cycles. The economic evaluation compares the operational savings incurred as a result of longer fuel cycles and reduced reactor downtime with increased fuel expenses, due to higher initial enrichment of uranium and downblending with thorium. Uranium fuel is compared with thorium-uranium fuel in terms of the fuel cycle costs, reactor downtime cost due to refueling, and income due to electricity sales. Thorium-uranium fuel costs more than uranium, but the income from electricity sales and reactor downtime refueling cost is advantageous. These factors have also been taken into account and prove that the advantage of increased income outweighs the higher fuel costs. Issues related to longer fuel cycles and higher burnups need to be addressed, but the development and adoption of once-through, homogeneous, thorium-uranium fuel can be justified by a clear economic benefit for utilities operating nuclear power plants.