The United Nations nuclear watchdog on Monday injected a ray of hope in the standoff over the beleaguered Zaporizhzhia atomic power plant, announcing that its mission of top experts “is now on its way” to the facility, which has seen relentless shelling as a focal point in the Ukraine war.

International Atomic Energy Agency director general Rafael Grossi has for months sought access to the Zaporizhzhia plant, Europe’s biggest, which has been occupied by Russian forces and run by Ukrainian workers since the early days of the 6-month-old war.

His announcement came hours after Russia and Ukraine traded claims of rocket and artillery strikes at or near the plant on Sunday, intensifying fears that the fighting could cause a massive radiation leak. Under the barrage of shelling last week, the facility was already temporarily knocked offline.

“The day has come,” Grossi wrote on Twitter, adding that the Vienna-based IAEA’s “Support and Assistance Mission … is now on its way.”

“We must protect the safety and security of #Ukraine’s and Europe’s biggest nuclear facility,” he wrote. “Proud to lead this mission which will be in #ZNPP later this week.” Grossi, who didn’t provide a more precise timeline or give further details, posted a picture of himself with 13 other experts.

Ukraine has alleged that Russia is essentially holding the plant hostage, storing weapons there and launching attacks from around it, while Moscow accuses Ukraine of recklessly firing on the facility. The Zaporizhzhia plant has six reactors.

The IAEA tweeted that the mission will assess physical damage to the facility, “determine functionality of safety & security systems” and evaluate staff conditions, among other things.

Ukraine’s atomic energy agency has painted an ominous picture of the threat by issuing a map forecasting where radiation could spread from the Zaporizhzhia plant, which Russian forces have controlled since soon after the war began. And on Monday, it accused the Russian forces of continued shelling the wider area.

Energoatom said in a statement that over the past 24 hours, Russian troops targeted the nearby city of Enerhodar and the power plant, wounding 10 people, four of whom worked at the plant.

Attacks were also reported over the weekend both in Russian-controlled territory adjacent to the plant along the left bank of the Dnieper River and along the Ukraine-controlled right bank, including the cities of Nikopol and Marhanets, each about 10 kilometers (six miles) from the facility.

Russian Defense Ministry spokesman Igor Konashenkov said Sunday that Ukrainian forces had attacked the plant twice over the past day, and that shells fell near buildings storing reactor fuel and radioactive waste.

“One projectile fell in the area of the sixth power unit, and the other five in front of the sixth unit pumping station, which provides cooling for this reactor,” Konashenkov said, adding that radiation levels were normal. It was not possible to independently verify the accusations.

The IAEA reported Sunday that radiation levels were normal, that two of the Zaporizhzhia plant’s six reactors were operating and that while no complete assessment had yet been made, recent fighting had damaged a water pipeline, since repaired.

But in a war now in its seventh month, Monday’s solitary piece of good news could hardly break the overall gloom that darkens everything from frontline villages to global food supplies and the world economy.