Latest updates, 1 April:
• Ukraine says Russian forces, who took control of Chernobyl on 24 February, have left and handed it back to Ukraine
• IAEA Director General Rafael Mariano Grossi holds talks in Kaliningrad with Russian officials about nuclear safety in Ukraine
• He says he will head an IAEA "assistance and support mission" mission to Chernobyl "as soon as possible"
• Director general says the IAEA has agreed a safety framework, agreed separately with Ukraine and with Russia
• The World Association of Nuclear Operators has transferred Ukraine’s nuclear operator Energoatom from its Moscow to its Paris centre

The International Atomic Energy Agency reports that the staff who volunteered to replace the workers who had been on-site for 25 days, have now themselves been there for nearly a week.

The International Atomic Energy Agency's Director General Rafael Mariano Grossi has said "we cannot afford to lose any more time" in concluding an agreed framework for ensuring nuclear safety and security in Ukraine.

Ukraine's nuclear regulatory authority has warned that the annual "fire season" is approaching in the area including Chernobyl and says that the usual firefighting capacity is not available as a result of the Russian occupation.

About half of the staff who were on shift on the day Russian forces took control of the Chernobyl site on 24 February, have been able to return home, Ukraine's nuclear regulator has told the International Atomic Energy Agency.

Ukraine says that the external power supply to Chernobyl has been restored five days after it was lost after power lines to the area were damaged during fighting.

• IAEA director general said Thursday's meetings showed both sides ready to work with the organisation
• Energoatom says Ukraine to switch to using Westinghouse rather than Russian fuel
• Nuclear power plants continue to operate in Ukraine, but concerns raised over conditions for workers
• IAEA and EBRD both 'concerned' by the situation at Chernobyl

Final testing is underway at the facility which will receive, process and dispose of solid radioactive waste from the decommissioning of Chernobyl. "This is a very important event," said the acting director general of Chernobyl nuclear power plant, Valery Seyda. "The last 'long-term construction' at the site is finally moving towards completion."

The project to dismantle the historic Chernobyl Shelter Object can begin, after Chernobyl NPP was granted the requisite licence today. The ageing Shelter has been superseded by the New Safe Confinement, which now surrounds unit 4 and contains equipment to undertake the work.

Ukraine's nuclear regulator has issued a permit to SSE Chernobyl Nuclear Power Plant for the retrieval of undamaged used nuclear fuel from the ISF-1 interim used fuel wet storage facility. The fuel will be moved into the new ISF-2 dry storage facility. The State Nuclear Regulatory Inspectorate of Ukraine has also issued a licence for the operation of the Liquid Radioactive Waste Treatment Plant at the Chernobyl site.

Many challenges have to be faced in maintaining safety over the long term in a damaged nuclear power plant following a severe accident, the OECD Nuclear Energy Agency notes in a new status report. The report reviews knowledge and experience gained through long-term management of the Three Mile Island, Chernobyl and Fukushima Daiichi accidents, by identifying and ranking main issues and knowledge gaps. It also reviews the existing regulations and guidance, practices, technical bases and issues regarding long-term management of a severely damaged nuclear site.

Thirty-five years on from the Chernobyl accident, Ukraine and the International Atomic Energy Agency have highlighted their commitment to cooperation in nuclear power. Meanwhile Ukraine’s nuclear regulator has launched the start of operations at a new storage facility for used nuclear fuel at the Chernobyl site.