Zaporizhia NPP (ZNPP) announced on its official Telegram channel that unit 4 had been transferred to "cold shutdown". Previously it was the only one of the plant’s six units to be maintained in hot shut down to provide heat to the plant itself and to the nearby operators’ town of Energodar. The plant noted that cold shutdown “is the safe state of the reactor when it is shut down at low pressure and low temperature of the cooling water”. At the same time, the residual heat removal system and the auxiliary cooling system continue to operate.
ZNPP noted that the work was carried out normally and in accordance with regulatory documents. “The limits and conditions of safe operation were not violated. The radiation background has not changed and is within natural limits.” The plant decided to take this step after Energodar ended the winter heating season.
International Atomic Energy Agency (IAEA) Director General Rafael Mariano Gross welcomed the development which had been recommended by the Agency for some time. “The Agency will continue to closely follow the operational status of the ZNPP and provide technically viable alternatives in a context of rapid changes and challenges,” he said.
ZNPP stopped generating electricity for the national grid in September 2022, but had kept at least one of its six units in hot shutdown since October 2022 to provide district heating and to process steam for liquid waste treatment at the site.
After the plant earlier this year started operating four newly-installed diesel steam generators to produce steam for the treatment of such waste, as recommended by the IAEA, unit 4 remained in hot shutdown primarily to provide hear to Energodar.
IAEA noted that, when in cold shutdown, in case the heat removal is interrupted for any reason, there is an additional response margin of several days before the cooling of the nuclear fuel in the reactor might be challenged. The reactor also needs less cooling water than in hot shutdown, an issue that became more challenging after the destruction of the downstream Kakhovka dam in June 2023.
“The decision to have all six units in cold shutdown is positive in itself, as the cooling down of the reactor provides an additional buffer in case of an accident. But it doesn’t address the fundamental issue of a recent sharp deterioration of the situation at the plant. Without a doubt, nuclear safety and security at this major nuclear facility remains very precarious,” Grossi said.
The potential risks were underlined when the team of the IAEA experts stationed at the site reported hearing sixteen rounds of outgoing artillery fire in less than half an hour – some at near distance, others further away but still clearly audible.
Earlier Grossi called for maximum military restraint and full observance of the five concrete principles for protecting ZNPP, days after a series of drone attacks had “significantly" increased the risk of a nuclear accident at the site. Addressing an extraordinary meeting of the IAEA Board of Governors he said it was of paramount importance to ensure that “these reckless attacks do not mark the beginning of a new and gravely dangerous front of the war”. The Board was convened by its Chair after he received two separate requests from both the Russian Federation and Ukraine.
“I firmly appeal to military decision makers to abstain from any action violating the IAEA’s five concrete principles to prevent a nuclear accident and ensure the integrity of the plant and I urge the international community actively to work towards a de-escalation of what is a very serious situation,” Grossi said in his opening statement.
The meeting was held less than a week after three drone strikes hit the site, endangering nuclear safety and security. This “shifted us into an acutely consequential juncture in this war”, he told the Board. Although the strikes – as well as others reported by the plant both before and after the events – did not cause damage compromising nuclear safety and security at the ZNPP, they marked a “major escalation” of the dangers.
“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 Zaporizhzhya NPP or any other nuclear power plant,” Grossi said.
Subsequently, Grossi also addressed the UN Security Council where he emphasised the importance of five principles he had established when he addressed the Council the previous year. These are:
- ???There should be no attack of any kind from or against the plant, in particular targeting the reactors, spent fuel storage, other critical infrastructure, or personnel;
- ???ZNPP should not be used as storage or a base for heavy weapons (i.e. multiple rocket launchers, artillery systems and munitions, and tanks) or military personnel that could be used for an attack from the plant;
- Off-site power to the plant should not be put at risk. To that effect, all efforts should be made to ensure off-site power remains available and secure at all times;
- ???All structures, systems and components essential to the safe and secure operation of ZNPP should be protected from attacks or acts of sabotage;
- ???No action should be taken that undermines these principles.
He said over the previous ten days, the first of these principles had been violated repeatedly “in what marks a step-change increase in risk to nuclear safety and security” at ZNPP.
Referring to the series of drone attacks on the plant he said: “These reckless attacks must cease immediately. Though, fortunately, they have not led to a radiological incident this time, they significantly increase the risk at Zaporizhzhya NPP, where nuclear safety is already compromised.”
He expressed concern about the context in which the attacks had occurred. “For several months before these direct attacks there had already been an increase in isolated drone incursions in the vicinity of the facility and in the nearby town of Energodar.” He also noted repeated loss of external power to the NPP site.
“We are getting dangerously close to a nuclear accident. We must not allow complacency to let a role of the dice decide what happens tomorrow. We must do everything in our power today to minimise the risk of an accident,” he concluded, stressing again the importance of the five principles.
Meanwhile, Russia’s Federal Service for Environmental, Technological and Nuclear Supervision (Rostekhnadzor) held a working meeting at ZNPP. Present were Rostecknadzor head Alexander Trembitsky and his deputy Alexey Ferapontov and ZNPP plant director Yuri Chernichuk. They supervised the transfer of unit 4 to cold shutdown and discussed extending the operating licences of the units, noting that ZNPP was already preparing a package of documents to support this in line with Russian regulations and IAEA recommendations.
"We know in what period and for which unit the operating organisation will apply to us for a licence,” said Trembitsky. “Unit 1 will be the first to approach the end of its operating licence…. We are also working to implement the certification and issuing of permits to operational personnel. The work is being carried out in a planned and systematic manner." Russian nuclear utility Rosenergoatom subsequently reported on the current status of the six ZNPP units – all now in cold shutdown. Unit one is undergoing repair; unit 2 is in reserve; unit 3 is undergoing repair; and units 4-6 are in reserve.
Image courtesy of Rosatom
