Ukraine has been preparing for a rotation of technical staff who have been working at the Chernobyl nuclear power station for the past two weeks, the International Atomic Energy Agency said.

Russian forces withdrew from the plant four days ago after being in control of the site for five weeks. During that time only one change of staff on duty took place, on 20-21 March. Many personnel live in the city of Slavutych outside the 30-km exclusion zone set up after the 1986 accident. Ukraine said the preparatory work for the next rotation included an assessment of staff security.

Out of the country’s 15 commercial nuclear reactors, Ukraine said seven were operating: two at the Russian-controlled Zaporizhzhya site, three at Rovno, and two at South Ukraine. The other reactors are shut down for regular maintenance or being held in reserve.