Reactor outages and output

Daily unit-level data for 95 U.S. reactors from the Nuclear Regulatory Commission and 82 European reactors from ENTSO-E grid data. U.S. archive covers 2025-08-21 to 2026-10-09.

As of 2026-10-09, 81 of 95 reporting U.S. power reactors were generating and 14 were at zero power. The reporting fleet was running at 84.8% of its combined rated output of 92,241 MW.

Units currently at zero power represent 13,731 MW of nameplate capacity. A reactor at zero power is not necessarily in trouble: refuelling outages are planned, happen roughly every 18 to 24 months, and typically last a few weeks.

Over the past year the capacity-weighted fleet capacity factor was 91.3%. Capacity factor is the share of rated output a reactor actually delivered, averaged over the period — it is the single most useful number for comparing how hard reactors are working, because it folds outages, refuelling and reduced-power operation into one figure.

This page covers the United States only, because the U.S. NRC is one of the few regulators publishing daily unit-level power data. Coverage of other countries depends on what their grid operators publish.

Reactors at zero power right now

Highest capacity factor over the past year

All U.S. reporting units

Europe — reactor output

Daily generation per unit from ENTSO-E grid data for 2026-10-11. Seven grid areas publish nuclear output at unit level; the rest of Europe does not, so coverage stops where the data does.

Units idle on 2026-10-11

Output below 10% of rated capacity. A unit sitting at a few megawatts is not generating: that is house load while the reactor is shut down, usually for refuelling.

ENTSO-E reports gross generation while the capacity figures here are net, so the last column can exceed 100% by a few per cent. That is expected and is why it is not labelled a capacity factor.

Where this data comes from

Every U.S. power reactor licensee reports its operating status to the NRC each morning. The NRC publishes the compiled figures as a daily status report covering the last 365 days. That file is a rolling window: older days drop off as new ones are added. WhereNuc archives each reading so the record keeps growing beyond what the source itself retains.

Capacity factors, outage durations and fleet averages on this page are calculated by WhereNuc from those daily readings; they are not part of the NRC file. Days with no reading are skipped rather than counted as zero, so a missing report does not look like an outage.

European figures come from the ENTSO-E Transparency Platform, where grid operators are required to publish generation per unit under EU Regulation 543/2013. Seven areas do so for nuclear: France, Spain, Czechia, Slovakia, Hungary, Bulgaria and the Netherlands. Belgium, Sweden, Finland, Switzerland, Slovenia and Romania do not publish at unit level, so their reactors are absent here even though the plants are on the map.

In Slovakia, Hungary and Bulgaria the data is reported per turbine generator rather than per reactor; WhereNuc sums the generators belonging to each unit. Where a name could not be matched to a reactor with confidence, the reading is left out rather than guessed.

NRC data is a work of the U.S. federal government and is in the public domain. ENTSO-E data is free to reuse with attribution. Machine-readable output: /api/reactor-status and /api/eu-reactor-status (add ?history=1 for the U.S. daily series). Completed outages and their durations are listed on the change log.