Shelling on Tuesday damaged a backup power line at the Russian-held Zaporizhzhia nuclear power plant (ZNPP) in Ukraine, which has already lost all four of its regular power lines, the U.N. nuclear watchdog said in a statement on Wednesday. 

The International Atomic Energy Agency (IAEA) said there was no immediate impact from the damage to one of its three backup power lines because the plant was already disconnected from the grid. Like all nuclear power plants, Zaporizhzhia needs power to keep cooling the nuclear fuel in its reactors and its spent fuel. Its one operating reactor is supplying power but with each external power line that goes down, it loses a line of defence against potential nuclear meltdown.