Power is back at Europe’s largest nuclear plant. IAEA warns the situation can’t last

The Zaporizhzhia nuclear power plant in Ukraine has restored some power, U.N. nuclear watchdog officials announced. It comes amid fears that total electricity loss would cause a nuclear accident.

Rafael Mariano Grossi, the director-general of the International Atomic Energy Agency, called the restoration of power “a temporary relief in a still untenable situation.”

“A protection zone is needed now,” he wrote on Sunday.

The Ukrainian plant went offline Saturday morning after Russian shelling damaged the last remaining outside power source. Nuclear plants rely on electricity to run their safety and cooling equipment. Without it, a meltdown could occur.

This is one of several times that the plant has lost external power in recent weeks.

Ukrainian authorities have tried using the plant’s own reactor and backup generators to supply some power, but those measures are not considered sustainable.

The six-reactor plant is the largest in Europe. It’s been captured and occupied by Russian forces since March, though some Ukrainian workers still operate the plant. The city is the capital of the Zaporizhzhia region, one of four Ukrainian territories that Russian President Vladimir Putin illegally annexed last month.

Efforts to prevent a radiation disaster have also been stymied by the fact that the city has repeatedly been a target of Russian blasts. That has left not only the plant vulnerable, but also local residents who rely on it for electricity.