The International Atomic Energy Agency said Friday that its expert mission would travel to Ukraine’s Chernobyl nuclear power plant on April 26 – the anniversary of the disaster for which the plant is known ­­– to help ensure the facility’s safety amid Russia’s ongoing invasion.

The Russian incursion has put at risk several nuclear facilities throughout Ukraine and represents the first time a country with an extensive atomic energy infrastructure has been invaded by a hostile neighbor.  Since the beginning of the conflict the IAEA, which is part of the United Nations,  has beseeched Russian troops to leave Ukraine’s nuclear plants out of the fight, without success.

Ukraine is home to 15 nuclear reactors spread across four nuclear power plants that it inherited upon its independence from the Soviet Union in 1991, and on which it relies for more than half of its electricity.

IAEA Director General Rafael Mariano Grossi will head the mission to “deliver vital equipment and conduct radiological and other assessments” at the Chernobyl plant, according to the agency’s statement, marking Grossi’s second visit to Ukraine since the war started.

The IAEA experts will also repair remote safeguards monitoring systems at the plant, which have not been transmitting data to the agency’s headquarters in Vienna since the start of the Russian invasion on February 24.

“The IAEA’s presence at Chernobyl will be of paramount importance for our activities to support Ukraine as it seeks to restore regulatory control of the plant and ensure its safe and secure operation,” Grossi said in a statement, adding that the agency will send more missions to Chernobyl and other nuclear facilities in Ukraine in the coming weeks.

Russian forces had been in control of the Chernobyl plant for five weeks before withdrawing on March 31, their heavy armored vehicles churning up radiation in some of the plant territory’s most irradiated territories.

According to Chernobyl plant workers, Russian troops had taken up positions throughout the exclusion zone, a 2,600 square kilometer area around the plant that has been uninhabited since shortly after the Unit Four reactor exploded on April 26, 1986.

Ukraine’s national nuclear operator, Energoatom, reported that Russian troops had dug trenches in irradiated ground and that numerous Russian soldiers had suffered radiation sickness as a result – though that hasn’t been independently confirmed.

The site, though decommissioned, houses several ongoing nuclear operations whose safety was threatened during the Russian occupation. Some 22,000 spend nuclear fuel assemblies risked overheating when fighting cut power to their cooling systems on March 9.

The power outage also affected radiation ventilation at the New Safe Confinement, the enormous steel dome covering the remains of Unit Four, where a delicate decade’s long effort to dismantle the reactor’s radioactive remains is underway.

Power was eventually restored, but the event underscored how vulnerable civilian nuclear facilities are to the whims of war.

That point was driven home again when the Zaporizhzhya nuclear power plant was attacked and fell into Russian hands on March 4 after an intense firefight. During the attack on the plant, which is Europe’s largest, Russian shelling destroyed a training laboratory located near one of the facility’s six reactors.

While conditions at the plant are now reported to be safe, Ukrainian staff continue to operate its reactors at gunpoint – a set of circumstances the IAEA has decried as dangerous.

There are also several spent fuel storage ponds at the Zaporizhzhia site, which like those at Chernobyl, also depend on outside power to operate their cooling systems.

Ukrainian regulators said yesterday that seven of the country’s reactors are currently connected to the electric grid, including two at Zaporizhzhya NPP, two at the Rivne nuclear plant, two at the South Ukraine nuclear plant, and one at the Khmelnytskyy nuclear plant. The eight that aren’t connected are being held in reserve to reduce cooling burdens or are undergoing maintenance.