Dresden 2 trips offline, unscheduled outage underway

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Dresden 2, Morris, Illinois.

Dresden 2 entered a forced short outage on 2026-09-04, ending a streak of 1226 days without an unscheduled outage. This event marks the first forced outage for the 902-MW General Electric BWR/3 unit during the 2026 calendar year.

The unit, which has been in commercial operation since 1970, recorded zero forced outages throughout 2025. Constellation Nuclear operates this unit alongside 20 other U.S. nuclear units. Across the current fleet of 94 units, the industry reports a 98.3 percent capacity factor with one unit currently in an unscheduled outage and zero units in refueling.

MORRIS, IL. Dresden 2 entered an unscheduled outage on Sep 4, 2026. The NRC has not yet issued an event notification for this trip; a follow-up reply will be posted here if one is filed.

This is the first unscheduled outage of 2026 for the unit. Its most recent outage was a 22-day refueling outage that ended in November 2025. Prior to this trip, the unit had gone more than 3 years without an unscheduled outage.

Across the U.S. fleet of 94 commercial reactors, today's combined capacity factor is 98.3% (1 unit in an unscheduled outage), above the 92.8% baseline for this month over the past five years. At the same site, Dresden 3 is running at full power. While the unit is down, that takes about 722,000 homes' worth of generation off the grid.

Dresden 2 is a 902-MW General Electric BWR/3 operated by Constellation Nuclear (commercial operation since 1970). The utility operates 20 other U.S. nuclear units. Its operating license runs through 2049 (renewed in 2025).

View Dresden 2's ratings, history, projections, and current status on NukeWorker. This thread will be updated when the unit returns to service.

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

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Follow-up: the NRC has filed its event notification for the Dresden 2 trip first reported in this thread. The agency classifies it as a manual reactor trip (docket 05000237).

MANUAL REACTOR TRIP The following information was provided by the licensee via phone and email: "At 0431 CDT on September 3, 2026, with Unit 2 in mode 1 at 100 percent power, the reactor was manually tripped due to indication of control rod movement and reactor protection system 'A' channel half scram, caused by nuclear instrumentation failure. The trip was not complex with all systems responding normally post-trip. Due to the reactor protection system actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). "Operations responded using station operating procedures and stabilized the plant in mode 3, [hot shutdown]. Decay heat is being removed by using the main turbine bypass valves. Unit 3 is not af...

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

Source: NRC event notification.

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Dresden 2 returned to service on September 9, 2026, following a six-day unscheduled outage caused by a scram. The unit returned to the grid two days ahead of the initial eight-day projection provided by NukeWorker.

This event marks the first forced outage for the 902-MW General Electric BWR/3 unit in 2026, following a year with zero forced outages in 2025. Constellation Nuclear operates Dresden 2 along with 20 other nuclear units in the United States. Across the industry, 94 units are currently maintaining a 95.7 percent capacity factor, with Davis-Besse as the only other unit currently in an outage.

Dresden 2 returned to service on Sep 9, 2026 after a 6-day unscheduled outage that began on Sep 4, 2026. A multi-day outage in this range typically points to a single equipment fix rather than a major component issue.

NukeWorker's projection had this at about 4 days at outage start; actual was 2 days longer.

The 6-day outage removed roughly 119,000 MWh from the grid, worth approximately $5 million at recent wholesale prices, equivalent to a year's electricity for about 11,000 homes.

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

Want the full picture? Subscribe to the NukeWorker outage schedule for every current and upcoming U.S. nuclear outage.

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