A team of the International Atomic Energy Agency (IAEA) left Kyiv on Wednesday for the Zaporizhzhia nuclear power plant in southern Ukraine.
"We are finally moving after six months of strenuous efforts," IAEA chief Rafael Grossi told reporters in the Ukrainian capital.
Grossi and his team arrived in Ukraine on Monday for inspections at Europe's largest nuclear power plant, which has been under Russian control since March.
Fears of a nuclear catastrophe have grown as the area has been shelled multiple times in recent days, with Russia and Ukraine blaming each other.
Grossi said the team will "be spending a few days" at the facility.
"These are complex operations. We are going to a war zone … (and) occupied territory. This requires explicit guarantees, not only from Russia but also Ukraine, and we have been able to secure that," he said.
The IAEA is also hoping to set up a permanent mission in Ukraine to monitor Zaporizhzhia, he added.
