Director General Rafael Mariano Grossi this week assessed the impact of the Kakhovka dam disaster on the safety of Ukraine's Zaporizhzhya Nuclear Power Plant (ZNPP) and reinforced the team of International Atomic Energy Agency (IAEA) experts at the facility, during his third visit to the site in less than a year.
The Director General and his team crossed the frontline to reach Europe's largest nuclear power plant (NPP) just over a week after the water level in the huge reservoir that supplies cooling water to the ZNPP started to drop significantly when the downstream dam was severely damaged on 6 June.
Earlier this week, he met with President Volodymyr Zelensky in Kyiv, presenting a new IAEA technical assistance package to help Ukraine cope with the subsequent flooding devastation through the application of nuclear science and technology in areas ranging from potable water, human health, soil and water management to integrity assessment of critical infrastructure.
His eighth mission to Ukraine since February 2022 took place amid reports of a Ukrainian counteroffensive being under way, including in the Zaporizhzhya region near the nuclear plant currently controlled by Russia.
"With military activities and tension intensifying in the area near the Zaporizhzhya Nuclear Power Plant, and with this month's dam catastrophe further complicating the facility's extremely challenging nuclear safety and security status, it was very important for me to travel to the site again to review developments on the ground, including the plant's ongoing and planned measures to manage the new water-related difficulties," Director General Grossi said.
During yesterday's stay at the ZNPP, Director General Grossi could see first-hand how the level of the Kakhovka reservoir had declined markedly over the past ten days - even exposing previously submerged sand banks - but also that the plant's large cooling pond and different channels at or near the site hold sufficient reserves to be able to provide cooling water in the short to medium term in case the reservoir can no longer be used.
At the moment, water from the discharge channel of the nearby Zaporizhzhya Thermal Power Plant (ZTPP) supplies the ZNPP's spray ponds, which cool the six shut down reactors and spent fuel, and also keeps the separate cooling pond full, mainly compensating for evaporation.
Together, the discharge channel and the large cooling pond can provide cooling water for some months provided they stay intact, although it is difficult to say exactly how long the existing water reserves can last in view of various external factors, such as evaporation and any future leaks.
There are also indications that some water resources from the reservoir itself currently remain available in areas near the ZNPP - where the water loss stopped a few days ago, unlike in other parts of the reservoir - but it is unclear if the level is high enough to pump it up for use at the plant. The pumps were last in operation about a week ago.
Together with a team of IAEA experts, Director General Grossi evaluated all the main parts of the site's water supply systems, including the gates separating the large pond and the ZTPP discharge channel from the reservoir, and how the plant is seeking to ensure that these bodies of water are kept secure and preserved.
For example, the plant has completed activities to seal and reinforce the isolation gates to prevent leakage. Director General Grossi witnessed how they had been reinforced with counterweights and sand.
"The integrity of these gates must be maintained to ensure that the plant has enough water for cooling the reactors. At the same time, it is essential that the plant implements a longer-term solution. The IAEA team can assist and advise in this work," he said.
The measures the plant is taking are buying it some extra time to prepare additional back-up water supply options, Director General Grossi added.
The plant informed the Director General that additional cooling water can be pumped from an underground water system and on-site wells. But he said it is not yet known whether these wells can reliably provide all the required water. New pumps that can potentially continue to access water at lower reservoir levels may also be installed.
"The breach of the dam has identified vulnerable points in the plant's water supply chain and there is a need to adapt the entire system to the new situation. But I could also see that the plant is taking concrete steps to address these challenges, stabilise the situation and enable the plant to ensure sufficient cooling water also in the future. The situation is serious, and it requires our continuous close monitoring. But, for now, it is being controlled," he said.
The Director General had planned his mission to the ZNPP already before the dam was damaged to follow up on the establishment at the UN Security Council on 30 May of five basic IAEA principles for the protection of the plant at a time of heightened military risks, including that there must be no attacks at or from the site and that it must not be used as a store for heavy weapons.
"From now on, we will be monitoring compliance with these principles, which are designed to prevent a nuclear accident during the armed conflict, which is showing clear signs of intensifying in the region where the plant is located. This requires a strengthened IAEA presence," he said.
Underlining the tense situation in the area, the Director General's convoy was stopped on the way back from the site visit, and gunfire was heard for a few minutes. But the convoy was not in immediate danger and the IAEA does not have any other information about the incident.
During this week's mission, the Director General carried out a new rotation of IAEA experts at the site, bringing with him the ninth such team since the mission at the site was established nearly ten months ago. Although the rotations continue to take place regularly, there have been several delays and postponements, sometimes caused by the weather and the general security situation.
He also went to the ZTPP a few kilometres from the nuclear plant, whose damaged electrical switchyard in the past has been used to provide 330 kilovolt (kV) back-up power to the ZNPP. The plant's last 330 kV back-up line was damaged almost four months ago, and the IAEA has requested access to the switchyard to check its status.
The ZNPP is continuing to operate one of the six reactors in hot shutdown to produce steam needed for wastewater treatment and a steam-driven cooling system that provides air conditioning for rooms equipped with instrumentation and control systems important to nuclear safety and security. Meanwhile the plant is also exploring alternate ways to meet the site's needs for generating steam and providing essential cooling. The five other units remain in cold shutdown.
Elsewhere in Ukraine over the past week, the IAEA also carried out rotations of its expert teams at the country's other NPPs - the Khmelnitsky, Rivne, South Ukraine and Chornobyl NPPs. In addition, the IAEA conducted its first medical assistance mission to the NPPs.
