IAEA reports 12-hour communications blackout at Zaporizhzhia nuclear plant amid regional fighting

What happened

The International Atomic Energy Agency (IAEA) reported on May 28 that the Zaporizhzhia nuclear power plant experienced a communications blackout for approximately 12 hours on May 27, losing both landline and internet connections. According to IAEA Director General Rafael Mariano Grossi, this outage was the longest at the facility since the onset of Russia's full-scale invasion of Ukraine in 2022.

Outside Brief is treating this as a source-led account. Any disputed responsibility, casualty figure or battlefield claim should be read as unconfirmed/hearsay unless confirmed by another reliable source. The cause of the communications loss is currently unclear, but it coincided with reported military attacks on the nearby Russian-occupied city of Enerhodar, where most plant staff reside. Grossi described the event as ‘very concerning’ for nuclear safety and security and said the IAEA is investigating the incident to prevent similar future occurrences.

This communications failure is notable because the IAEA had previously established seven core principles for maintaining nuclear safety during wartime, one of which mandates reliable communication between nuclear sites and regulatory or external authorities. The blackout represents a clear violation of this principle at an already high-risk facility.

Known from the source

• The Zaporizhzhia nuclear power plant lost landline and internet communications for about 12 hours on May 27, 2026.
• This outage is the longest communications blackout at the plant since the start of Russia’s full-scale invasion of Ukraine.
• The plant is under Russian military occupation but located in Zaporizhzhia Oblast, where the regional capital remains under Ukrainian administration.
• The blackout occurred alongside reported attacks on Enerhodar, a nearby city occupied by Russian forces and home to most plant employees.
• The IAEA considers reliable communication a core wartime nuclear safety principle and described the outage as a concerning event for safety and security.

What remains unclear

The Zaporizhzhia plant, the largest nuclear power station in Europe and among the top ten globally, remains under Russian military occupation along with much of the surrounding Zaporizhzhia Oblast. Meanwhile, the regional capital and most of the population remain under Ukrainian control. Earlier this month, the IAEA had reported increased drone activity near multiple Ukrainian nuclear plants, warning of significant safety risks despite no direct damage so far.

What remains unclear: Exact cause of the communications blackout at Zaporizhzhia plant on May 27. Verification of reported attacks on Enerhodar coinciding with the outage. Any additional IAEA updates on the investigation into the outage. Technical details on how communications were disrupted.

Evidence note

Outside Brief has kept this brief source-led and attributed. Claims should be read alongside the original source linked below.

Original source: Kyiv Independent. Open the source.