Cooper trips offline, unscheduled outage underway

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Cooper, Brownville, Nebraska.

Cooper entered an unscheduled outage and was reported at 0% power in the NRC daily report of Nov 2, 2026. This marks the 1 forced outage for the unit so far in 2026, compared to 0 in all of 2025, closely following a 34-day refueling outage that ended Oct 31, 2026. The NukeWorker forced-outage duration projection is about 4 days.

BROWNVILLE, NE. Cooper was reported offline in the NRC's Nov 2, 2026 daily power report, beginning an unscheduled outage. 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. The unit had just returned to service on Oct 31, 2026 from a 34-day refueling outage.

Based on the unit's history and similar reactor types, projected total duration is about 4 days.

Across the U.S. fleet of 94 commercial reactors, today's combined capacity factor is 82.4% (16 units currently refueling, 1 unit in an unscheduled outage), below the 88.0% baseline for this month over the past five years. While the unit is down, that takes about 618,000 homes' worth of generation off the grid.

Cooper is a 772-MW General Electric BWR/4 operated by Nebraska Public Power District (commercial operation since 1974). Ownership history: Entergy took over managing it from Nebraska Public Power District in October 2003, and Nebraska Public Power District took over managing it from Entergy in March 2022. Its operating license runs through 2034 (renewed in 2010).

View Cooper's ratings, history, projections, and current status on NukeWorker. This thread will follow the restart and power ascension. Get a free email alert the moment it comes back online.

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

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Follow-up: the NRC has filed its event notification for the Cooper trip first reported in this thread. The agency classifies it as a manual reactor trip (docket 05000298).

MANUAL REACTOR SCRAM The following information was provided by the licensee via phone and email: "On November 1, 2026, at 0454 CST, with the unit in Mode 2, [startup], at 9 percent power [starting up following a refueling outage], the reactor was manually tripped due to elevated vibrations on the only feedwater pump in service. The trip was not complex, with all systems responding normally post-trip. "Operations stabilized the plant [in Mode 3, hot shutdown]. Reactor water lever is being maintained with the control rod drive system. "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). "There was no impact on the health and safety of the public or plant personnel. [...]

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

Source: NRC event notification.

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Cooper restarted following a manual reactor trip on Nov 1, 2026, spending 6 days at 0% power in NRC daily reports, which was 2 days longer than the initial 4-day projection. Power was reported above 0% on Nov 8, 2026, though the unit remained at 0% power as of Nov 10, 2026, while still ramping up. This event marks 1 forced outage for the unit so far in 2026, compared to 0 in all of 2025.

Cooper has restarted after a manual reactor trip on Nov 1, 2026. The unit sat at 0% power for 6 days in the NRC's daily reports (Nov 2, 2026 to Nov 7, 2026). As of the NRC's Nov 10, 2026 report, Cooper was again at 0% power. After its last 4 forced outages, the unit took a median of 2 days to climb from restart to full power.

NukeWorker's projection at outage start was about 4 days; the unit was offline 2 days longer than that.

The 6 days at 0% power cost roughly 111,000 MWh of generation, worth approximately $4 million at recent wholesale prices.

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

Source: NRC Daily Reactor Power Status reports and event notification.