Enerhoatom said the International Atomic Energy Agency (IAEA) team had arrived at the Zaporizhzhia plant that has been in the thick of recent fighting between Ukrainian and Russian forces more than six months after Russian president Vladimir Putin ordered his troops to invade Ukraine.
The company said earlier on Thursday that Russian mortar shelling had led to the shutdown of one of its reactors by its emergency protection system.
Shelling had also damaged a backup power supply line used for in-house needs, and one of the plant’s reactors that was not operating had been switched to diesel generators, the company said.
Speaking earlier, the team’s director Rafael Grossi said: “There has been increased military activity, including this morning until very recently.
“But weighing the pros and cons and having come so far, we are not stopping.”
He noted that the risks were “very, very high” in the so-called grey zone between Ukrainian and Russian positions, but “we consider that we have the minimum conditions to move”.
A spokesman for the IAEA later said that the mission had been delayed on the Ukrainian-controlled side of the front line for some three hours, adding that Mr Grossi “has personally negotiated with Ukrainian military authorities to be able to proceed and he remains determined that this important mission reaches the ZNPP (Zaporizhzhia Nuclear Power Plant) today”.
The Zaporizhzhia plant has been occupied by Russian forces but run by Ukrainian engineers since the early days of the war.
Ukraine alleges Russia is using the plant as a shield, storing weapons there and launching attacks from around it, while Moscow accuses Ukraine of recklessly firing on the area.
Fighting in early March caused a brief fire at its training complex, and in recent days, the plant was temporarily knocked offline because of damage, heightening fears of a radiation leak or a reactor meltdown.
Officials have begun distributing anti-radiation iodine tablets to nearby residents.
“We have a very important mission to accomplish,” Mr Grossi said, adding that “we are going to start immediately an assessment of the security and the safety situation at the plant”.
“I am going to consider the possibility of establishing a continued presence of the IAEA at the plant, which we believe is indispensable to stabilise the situation and to get regular, reliable, impartial, neutral updates of what the situation is there,” he added.