The International Atomic Energy Agency (IAEA) Director General Rafael Mariano Grossi has been urging the Russian operators of the occupied plant to put all its units into cold shutdown, as part of efforts to minimise risks to nuclear safety and security.
In a message posted on its Telegram channel, the plant operators announced that on Friday at 07:00 local time, "specialists began cooling down the N4 power unit. The process is organised in accordance with all necessary norms and regulations. The work is progressing normally".
The plant, which has been under Russian military control since early March 2022, stopped generating electricity in September 2022 but has kept one of its units in 'hot shutdown' to provide heating for the plant and the nearby town of Energodar, as well as for process steam for liquid waste treatment at the site.
Earlier this year four diesel steam generators were installed to handle the waste requirements, and the decision to move the unit into cold shutdown follows the official end of the winter heating season at Energodar. The advantage of cold shutdown is, the IAEA says, "there is an additional response margin of several days before the cooling of the nuclear fuel in the reactor might be challenged" and it also requires less cooling water.
Grossi said: "Switching to cold shutdown is a positive step for nuclear safety and security, although one that is currently overshadowed by the great military dangers facing the plant."
The director general was speaking as the IAEA's Board of Governors held an extraordinary meeting following the drone attacks on and around the plant over the past few days, which he said was the first time it had been directly targeted since November 2022.
Grossi, who is to address the United Nations Security Council on Monday, said the events of the past weeks had breached the five principles for nuclear safety and security agreed by the UN Security Council last May. These included that there should be no attack on, or from, a nuclear power plant.
He told the meeting: "As I have repeatedly stated - including at the Security Council and the IAEA Board of Governors - no one can conceivably benefit or gain any military or political advantage from attacks against nuclear facilities. Attacking a nuclear power plant is an absolute no-go ... Sunday’s attack fortunately did not compromise nuclear safety in a serious way, but it would be irresponsible for us to assume future attacks will not. Rolling the dice is not the way to do it in nuclear safety."
He added: "I urge you to make this your highest priority and to support me and the IAEA in doing everything in your power to stop this devastating war becoming unconscionably more dangerous through further attacks on the Zaporizhzhia NPP or any other nuclear power plant."
In his update, Grossi said that the IAEA experts stationed at the Zaporizhzhia plant visited the main control rooms of all six units, the off-site radiation monitoring laboratory and the radioactive waste storage facility but were not granted access to parts of unit 2's turbine hall or some parts of the waste facility.
"In these extremely challenging circumstances, the presence of IAEA experts ... is more important than ever. Their impartial and technical work enables us to inform the world about events there in an independent and timely manner. In order to carry out these crucial tasks, they need prompt and unrestricted access to all areas that are important for nuclear safety and security," Grossi said.
He said that the IAEA teams stationed at the Khmelnitsky, Rivne and South Ukraine nuclear power plants and the Chernobyl site report that nuclear safety and security is being maintained "despite multiple air raid alarms that occurred over the past week".
The Russian operators of the plant said that representatives of Russia's nuclear regulator Rostechnadzor had visited Zaporizhzhia unit 4 this week "and checked its readiness for cooling down". They also reported that "work is under way ... to prepare for extending the operating life of power units and certifying personnel".
