Marc Santora and
The urgency of the mission to a nuclear power plant in southern Ukraine caught in the middle of a raging war was underscored even before the team of international inspectors set off on Thursday morning into Russian occupied territory as artillery boomed in the distance.
Only hours earlier, renewed shelling at the Zaporizhzhia Nuclear Power Plant had forced the shutdown of one of two working reactors, and for the second time in less than two weeks, emergency diesel generators had to be switched on to keep the plant running safely, Ukrainian energy officials said.
Rafael Mariano Grossi, the director general of the International Atomic Energy Agency who led the team of inspectors, said the peril of the moment justified the risks of the journey.
But even after the team safely reached the plant and gave it an initial four-hour inspection, it was far from clear what the mission could ultimately accomplish.
The crisis at the plant is about a battle for control of the facility itself, now occupied by Russian forces but operated by Ukrainian engineers working under near daily bombardment.
The agency has no authority to order a cease-fire or to demand the creation of a demilitarized zone — the two steps outside experts say would provide the fastest way to limit the risk of a nuclear catastrophe.
Russia has rejected both ideas.
The U.N. agency is also not designed to investigate and assign blame for the shelling of the plant. Russia and Ukraine have accused each other of shelling the sprawling plant, which has six reactors.
Still, the visit was the first time independent monitors have been able to assess conditions at the plant — no small thing given that it remains far from clear how much damage has been done to critical equipment since Russian forces first stormed the facility in early March.
The immediate checklist for the monitors, according to people familiar with the mission, was to ensure the plant’s most critical emergency equipment is operational and in good working order. That included checking to see there were adequate supplies of fuel for the emergency diesel generators and sufficient reserves of high-quality water that can be reliably delivered to supply emergency pumps.
Ukrainian officials wanted the I.A.E.A. to be allowed to keep monitors on site after the mission is complete, in the hopes their mere presence will create better conditions for the workers. Mr. Grossi, in brief remarks broadcast as he toured the facility, said five monitors would remain at the plant until at least Saturday. “We are establishing a continued presence from the I.A.E.A. here,” he told reporters.
The Ukrainians also called on the I.A.E.A. to do a detailed study of all critical systems over at least a 24-hour period and release the results — a safeguard against what they fear will be coerced statements by workers at the plant speaking under Russian intimidation.
Mr. Grossi has not said how his team will communicate their findings, but some experts hoped he would use the authority vested in the I.A.E.A. to increase pressure on Russia to cycle down all the reactors until the fighting ends.