KYIV, Ukraine (AP) — Concern about the potential for a radiation leak at Europe's largest nuclear power plant persisted as Ukrainian authorities said Saturday that Russian forces fired on areas just across the river and Russia claimed Ukrainian shelling hit a building where nuclear fuel is stored. 

Authorities were distributing iodine tablets to residents who live near the Zaporizhzhia Nuclear Power Plant in case of radiation exposure, which can cause health problems depending on the amount a person absorbs.

Much of the concern centers on the cooling systems for the plant's nuclear reactors. The systems require power to run, and the plant was temporarily knocked offline Thursday because of what officials said was fire damage to a transmission line. A cooling system failure could cause a nuclear meltdown.

Russian forces occupied the nuclear plant complex early in the 6-month-old war in Ukraine, and Ukrainian workers have kept it running. The Ukrainian and Russian governments have repeatedly accused the other of shelling the complex and nearby areas, raising fears of a possible catastrophe.

Periodic shelling has damaged the power station's infrastructure, Ukraine’s nuclear power operator, Energoatom, said Saturday. "There are risks of hydrogen leakage and sputtering of radioactive substances, and the fire hazard is high,” it said.