Byron 2 completes Fall refuel in 27 days, caps 514-day B2B run

[Core Content]

Byron 2, Byron, Illinois.

The Byron 2 routine refueling outage ran 6 days longer than the planned 21 days, totaling 27 days at 0% power. The 27 day duration ranks as the third-longest among the unit's 19 tracked refuels, following an outage period from Sep 28, 2026 to Oct 24, 2026. The unit returned to full power at 100% as of the NRC report of Oct 29, 2026, entering the refuel with more than 9 years without an unscheduled outage.

27 days outage · 6 days past schedule · 12th B2B run complete · 1,136 MW back at full power

Byron 2 completed its Fall 2026 refueling outage, reaching full power on Oct 29, 2026 after 27 days offline. The outage began on Sep 28, 2026. The reactor was critical by the NRC's Oct 25, 2026 report and back on the grid by Oct 27, 2026. First power to full power took 4 days.

The published schedule had it at 21 days (Sep 28, 2026 to Oct 19, 2026), so the actual ran 6 days longer than planned.

It is the unit's third-longest refueling outage of 19 cycles tracked since 1999. It also capped a 514-day breaker-to-breaker run, the unit's 12th qualified B2B run. Going into the refueling, the unit had run for more than 9 years without an unscheduled outage.

Counting the 27 days offline and the climb back to full power, the outage cost roughly 780,000 MWh of generation, worth approximately $31 million at recent wholesale prices.

Across the U.S. fleet of 94 commercial reactors, today's combined capacity factor is 83.3% (16 units currently refueling), above the 81.8% baseline for this month over the past five years. At the same site, Byron 1 is running at full power. Vogtle 2, D.C. Cook 1, North Anna 2, and Callaway also completed refueling outages within the past week.

Byron 2 is a 1,136-MW Westinghouse 4-loop PWR operated by Constellation Energy (commercial operation since 1987). At full power, it supplies enough electricity for roughly 909,000 homes. The utility operates both units at this site and 19 more at 11 other U.S. plants. Ownership history: Exelon took it over in an October 2000 merger with Commonwealth Edison (Unicom), and Constellation Energy took it over in Exelon's February 2022 spin-off. Its operating license runs through 2046 (renewed in 2015). The unit ran at a 93.9% capacity factor in 2025, a solid year of operation.

View Byron 2's ratings, history, projections, and current status on NukeWorker.

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Sources: NRC Daily Reactor Power Status reports, validated outage schedules, and NukeWorker's projections.