Since being cut off from the grid, the station was relying on its own power supplies to operate essential safety mechanisms. Experts feared that the plant could run out of internal power.
SMRs are essentially pressurized water reactors identical to some 400 reactors worldwide.
The IAEA experts learned that the reserve line linking the facility to a nearby thermal power plant was delivering the electricity the plant generates to the external grid.
Kyiv suspects Moscow intends to divert power from the Zaporizhzhia plant to the Crimean Peninsula, annexed by Russian troops in 2014.
A radiation disaster was narrowly avoided after the Zaporizhzhia nuclear plant was cut off from the country's power grid.
The Zaporizhzhia plant -- Europe's largest nuclear facility -- has been occupied by Moscow's troops since the opening weeks of the war.
A flare-up in fighting around the Russian-controlled nuclear power station -- with both sides blaming each other for attacks -- has raised the spectre of a disaster worse than in Chernobyl.
The 15-nation Council held an emergency session, called by Albania, France, Ireland, Norway, the United Kingdom and the United States on Friday.
The assault triggered a phone call between U.S. President Joe Biden and Ukrainian President Volodymyr Zelenskyy, and the U.S. Department of Energy activated its nuclear incident response team.