ZAPORIZHZHIA, Ukraine — Experts from the United Nations’ nuclear watchdog agency are poised to cross a front line in Russia’s war in Ukraine to inspect the imperiled Zaporizhzhia Nuclear Power Plant, embarking on one of the most complicated missions in the agency’s history.
The group of 14 experts with the International Atomic Energy Agency left the Ukrainian capital of Kyiv early Wednesday morning in a convoy of armored S.U.V. vehicles and traveled south to a city near the plant, stopping for the night. The visit to the plant, planned for Thursday morning, will entail crossing a buffer zone of fields cratered with artillery shells between the two armies.
The agency’s director general, Rafael Mariano Grossi, said on Wednesday that he hoped to spend “several days” at the site as independent nuclear scientists gauged the state of the plant, but local officials aligned with the Russian army suggested it would be a more abbreviated visit of one day. Mr. Grossi said the mission had secured safety guarantees from the Russian and Ukrainian militaries, but he noted, “We are going to a war zone.”
Inspectors have to cross checkpoints along with civilian traffic, a Russian official said, and it was unclear how quickly Moscow’s forces would allow them to pass into Russian-held territory.
In brief comments to reporters, Mr. Grossi said his team included “very experienced people, the best and the brightest,” who would provide the world a first impartial view of the risks posed by combat to the station’s six nuclear reactors and radioactive waste storage sites.
“We will have a pretty good idea of what is going on,” he said. The visit, he said, “is a mission that seeks to prevent a nuclear accident.”
The plant, which is controlled by Russian forces but operated by Ukrainian engineers, is in the middle of an active battlefield and frequent shelling has raised fears of a nuclear catastrophe. On Wednesday afternoon, the inspectors reached the Ukrainian-controlled city of Zaporizhzhia, which lies about 76 miles to the north of the plant.
As the team traveled south from Kyiv, a Russian official said Moscow would support plans for the inspectors to set up a permanent presence at the facility. Mikhail Ulyanov, Moscow’s envoy to the I.A.E.A, wrote in a tweet that Russia “welcomes” the agency’s objective, though he did not say when such a mission would begin.
The Russian-appointed head of the Zaporizhzhia region, Yevhen Balytskyi, said earlier on Wednesday that the visit was expected to last only one day, calling the delegation’s stated goal for the visit vague.
“They have one day to inspect the operation of the plant,” he said, adding, “If they say some elements need to be attended to, we’ll be able to do so.”
Vladimir Rogov, an official in the Russian army’s occupation administration in the area around the plant, said the inspectors would be made to wait in line with others trying to pass through checkpoints.
Ukraine has insisted that the inspectors start out from government-controlled territory, to avoid giving legitimacy to the Russian occupation, meaning inspectors must pass through frontline positions.
“They will not be provided with a special pass,” Mr. Rogov said. “They had a chance to come from Russia through the liberated territory safely, quickly and without obstacles.”