Impact of High Burnup on PWR Spent Fuel Characteristics

Reducing the burden of management of spent nuclear fuel is important to the future of nuclear energy. The impact of higher pressurized water reactor (PWR) fuel burnup is examined in this paper from the perspective of its impact on spent-fuel radioactivity, decay heat, and plutonium content. The necessary fresh fuel enrichments to achieve high burnup in PWRs with the same three-batch operation scheme are first computed; then, characteristics of the spent fuel are determined. The increase in decay heat with burnup is found to be generally less than linear. Although each high-burnup fuel assembly would be hotter and more radioactive, the total decay heat to be removed or accommodated in storage is less for the same electricity production. If the time window before 150 yr after discharge can be excluded from impacting a repository, significant savings in its capacity can be realized with high-burnup fuel. The high-burnup fuel is more proliferation resistant because of reduced total plutonium production per kilowatt hour and because of higher content of less desirable plutonium isotopes, such as ²³⁸Pu. The fuel cycle cost can be slightly reduced by increasing burnup until it reaches a shallow minimum near 70 MWd/kg. Higher burnups would require one-time changes to the limits on enrichments that can be handled in most commercial fuel fabrication facilities. Changing the waste fee to base it on the amount of radioactivity in the spent fuel would enhance the economic benefit of high burnup.