Extended Power Uprates and 2-yr Cycles for BWRs - Where Do We Go from Here?

Boiling water reactors (BWRs) in the United States have transitioned over the past 30 yr from 7 × 7 and 8 × 8 fuels, 12-month cycles, and batch average burnups of 30 GWd/tonne U to 10 × 10 fuel, 18- to 24-month cycles, batch average burnups of 50 GWd/tonne U, and 5% power uprates in the 1990s. The next step for BWRs in the new millennium is 24-month cycles and extended power uprates as high as 120% power. These operating conditions lead to large reload fuel batch sizes (up to 45% of the core) that result in lower batch average discharge burnups (~45 GWd/tonne U). Parameters driving the drop in fuel burnup include enrichment limitations and the need for fuel performance improvements. The next steps to achieve better BWR fuel cycle economics and their associated benefits and implementation challenges are discussed in this paper.