The fuel cycle economics of improved uranium utilization in light water reactors

Abstract

A simple fuel cycle cost model has been formulated, tested satisfactorily (within better than 3% for a wide range of cases) using a more elaborate computer program, and applied to evaluate a variety of PWR fuel cyclesand fuel management options, with an emphasis on issues pertinent to the NASAP/INFCE efforts. The uranium and thorium cycles were examined, lattice fuel-to-moderator and burnup were varied, and once-through and recycle modes were examined. It was found that increasing core burnup was economically advantageous, particularly if busbar or total system cost is considered in lieu of fuel cycle cost only, for both once-through and recycle modes, so long as the number of staggered core batches is increased concurrently. When optimized under comparable ground rules, the once-through fuel cycle is competitive with the recycle option; differences are well within the rather large (+ 20%) one sigma uncertainty estimated for the overall fuel cycle costs by propagating uncertainties in input data. Optimization on mills/kwhre and ore usage, tones/GWe,yr, are generally, but not universally, compatible criteria. To the extent evaluated, the thorium fuel cycle was not found to be economically competitive. Cost-optimum thorium lattices were found to be drier than for current PWRs, while cost-optimum uranium lattices are essentially those in use today. The cost margin of zircaloy over stainless steel decreases as lattice pitch is decreased, to the point where steel clad could be useful in very dry cores where its superior properties might be advantageous. Increasing the scarcity-related escalation rate of ore price, or the absolute cost of ore, does not alter any of the major conclusions although the prospects for thorium and recycle cores improve somewhat.