Perspective to fuel design and performance improvements in pressurized water reactors

One of the most straightforward means of power generation economics is to develop the technology supporting extended burnup of UO2 fuel. The concept of extended burnup represents no major departure from current fueling practices but rather is consistent with the historical trend of increased fuel exposure with time and accumulation of irradiation experience. The present nominal design specification of the PWR industry is 33,000 MWd/tU for three annual cycles of irradiation. This specification, however, is primarily based on fuel vendor warranties and utility fuel management practices rather than on any fundamental design limitation. A substantial economy can be realized if the discharge burnup is increased in relation with some cycle length options. Management is now predisposed to any scheme which reduced the number of refueling outages and reduced the discharge rate of spent fuel. Using current economic assumptions, the extended burnup cycle using four batch fuel management exhibits fuel cycle costs that are 7% lower than those of the reference cycle. The savings result from the significantly lower cost associated with fuel fabrication and spent fuel management, as well as the savings in U3O8 and separative work. Since the beginning of the nuclear electricity development the general philosophy about the fuel cycle has been continued without any change in spite of leaving the gas cooled reactor type, using natural uranium, for the pressurized water reactor type using slightly enriched uranium. The fuel cycle includes reprocessing and recycling of the produced plutonium in fast breeder reactors which are now an industrial reality. For the future the non perfect adaptation of the plutonium production to the plutonium needs result in recycling uranium and plutonium in thermal reactors with the same flexibility than UO2 fuel. (author)