With Disaster Looming, Inspectors Set to Visit Ukraine Nuclear Plant

KYIV, Ukraine — As renewed shelling intensified fears about a nuclear accident at the Zaporizhzhia power plant, the Ukrainian authorities stepped up emergency drills on Saturday and rushed to hand out potassium iodide, a drug that can protect people from radiation-induced thyroid cancer, to tens of thousands of people living near the facility.

In a country still haunted by the memory of the 1986 Chernobyl nuclear disaster, officials urged the public not to panic even as complex negotiations to allow for a team of scientists from the International Atomic Energy Agency to visit the Russian-controlled plant in southeastern Ukraine took on added urgency.

The agency, the United Nations’ nuclear watchdog, has assembled a team of experts to travel to Zaporizhzhia — Europe’s largest nuclear power station — as early as next week.

A list of the team’s members seen by The New York Times includes the nuclear agency’s chief, Rafael Mariano Grossi of Argentina, and 13 other experts from mostly neutral countries. Neither the United States nor Britain, countries that Russia scorns as unfairly biased because of their strong support for Ukraine, is represented.

The I.A.E.A. headquarters in Vienna declined to comment on the planned mission. A spokesman confirmed that the agency was “in active consultations for an imminent I.A.E.A. mission” to the plant.

But even as the details of a possible visit to the plant took shape, Russia and Ukraine again blamed each other for endangering the facility, which lies in the middle of a war zone.

Ukraine’s nuclear energy agency, Energoatom, said Russia had shelled the plant late Friday and into Saturday morning. It also accused Russian forces of increasing pressure on the plant’s staff ahead of a possible I.A.E.A. visit “to prevent them from disclosing evidence about the crimes of the occupiers at the plant and its use as a military base.”

Within minutes of Energoatom’s statement, Russia’s Ministry of Defense put out its own statement saying that Ukraine had fired shells at the plant in the past 24 hours.

It was not immediately possible to confirm either account.

For now, both the Russians and the Ukrainians said radiation levels remained within normal range.

But President Volodymyr Zelensky of Ukraine said in an address to the nation late Friday that the plant’s disconnection from the national power grid a day earlier had brought it perilously close to disaster, making the need for a visit by international inspectors even more urgent.

“I want to emphasize that the situation remains very risky and dangerous,” Mr. Zelensky said, hours after the plant was reconnected to the grid. “That is why it is so important that the I.A.E.A. mission arrives at the plant as soon as possible.”

Authorities have started to hand out the iodine pills as a precaution to people living within 35 miles of the plant. That area, home to an estimated 400,000 people in both Ukrainian and Russian-occupied territory, would be most at risk in the event of an accidental leak of radiation.

The Ukrainian minister of health, Viktor Liashko, cautioned in an appearance on national television that people did not need to buy the pills, “as we have purchased the drug in exactly the dosage recommended by our researchers.”

“One pill will be enough for the first stage. That’s all,” he said. “But at the moment, if it’s not distributed to people, it is solely for the reason that there is no need to do so, or to ensure that people don’t take it for preventive purposes, out of fear.”

Potassium iodide, also known by the chemical symbol KI, is used to saturate the thyroid gland with iodine so that inhaled or ingested radioactive iodine is not retained.

Dmytro Orlov, the exiled mayor of Enerhodar, the Russian-occupied town that is next to the nuclear power plant, said that while radiation levels around the plant were all within normal range, 25,000 iodine tablets were being distributed through personal doctors as a precaution. The Russians control the pharmacies in the city, residents say, but many physicians have kept working and can still distribute medicine.

The Ukrainian regional authorities were also revising their public warning systems and evacuation plans in the event of an emergency. A notification system has been designed to warn people living both in government-controlled territory and areas under Russian occupation, said Oleksandr Starukh, the head of the Zaporizhzhia regional military administration.

“Since there will be no time to think in the event of real danger from the actions of the Russian invaders, it will be necessary to strictly adhere to the preapproved action plan,” he said. “Everything and everyone should work as a single mechanism.”

The plant on Thursday temporarily lost all of its off-site electrical power from Ukraine’s national grid, forcing it to rely on backup diesel-fueled generators for power and renewing concerns about its safe operation.

Edwin Lyman, a nuclear power expert at the Union of Concerned Scientists, a private group in Cambridge, Mass., said it did not appear that the plant’s safety systems had suffered significant damage, but warned that could change quickly if the conflict escalated.

“Thursday’s incident did bring this plant closer to the brink of a crisis than we have previously seen and should be a warning call about how vulnerable it is,” Mr. Lyman said in a phone interview.

He said that a visit to the plant by experts from the International Atomic Energy Agency could help begin the implementation of measures that would lessen the risk of an “entirely preventable” disaster.

Ideally, said Mr. Lyman, who recently wrote an extensive review of the safety problems at the plant, all parties would agree to create a demilitarized zone around the facility, something Russia has so far resisted. Short of that, he said, a visit by the I.A.E.A. would allow experts to inspect the plant’s emergency response procedures and systems, as well as ensure a robust supply of diesel fuel for the backup generators and other diesel-powered emergency equipment at the site.

Despite mounting international anxiety over a possible catastrophe at the sprawling plant, Russia and Ukraine for weeks have failed to agree on a plan that would allow inspectors to visit. The continued shelling is complicating those discussions.

The warring nations have haggled over not just the composition of the inspection team but also whether it would travel to the plant through territory occupied by Russian forces or controlled by the government in Kyiv.

Ukraine has insisted that the inspectors start out from government-controlled territory, to avoid giving legitimacy to the Russian occupation. That means the inspectors would have to pass through frontline positions where shelling is frequent and would probably use a crossing point already crowded with civilians fleeing the fighting and nuclear dangers. Any deal is likely to require a cease-fire along the route.

Moscow has said it supports the work of the I.A.E.A., but has ignored pleas to withdraw military forces from the plant and its vicinity to create a demilitarized zone. Russia seized the facility, which comprises six nuclear reactors, in March at the start of its invasion, but Ukrainian engineers still operate it.

The I.A.E.A. mission includes experts from Poland and Lithuania, nations seen as friendly by Ukraine, but also others from Serbia and China, which Ukraine views with deep suspicion because of their cozy relations with Moscow.

The remaining members are from countries that have mostly stood on the sidelines of the war or that have kept channels open with the Kremlin. They include Albania, France, Italy, Jordan, Mexico and North Macedonia.

A senior diplomat familiar with the negotiations said that Russia had given its approval to the inspection team and indicated that it had acceded to Ukraine’s demand that the mission originate in territory it controls.

Marc Santora reported from Kyiv and Katrin Bennhold from Berlin.