Ukraine's Zaporizhzhya Nuclear Power Plant (ZNPP) has increased the number of reactors in hot shutdown to two units and has also started operating mobile diesel boilers as part of efforts to generate more heating during the winter, including to the nearby town of Enerhodar, Director General Rafael Mariano Grossi of the International Atomic Energy Agency (IAEA) said today.
The ZNPP ceased producing electricity for the national grid in September last year. Since April 2023, Europe's largest nuclear power plant (NPP) has kept five reactors in cold shutdown and just one in hot shutdown to generate steam to process liquid radioactive waste and for other safety related functions.
Ahead of the upcoming winter months, however, it started transitioning a second reactor, unit 5, to hot shutdown last week. The reactor reached hot shutdown early on 16 October, joining unit 4 in this operational status. Both are now providing steam for the site and district heating to Enerhodar, where many plant staff live.
The IAEA has been encouraging the ZNPP over many months to find an alternative source of steam generation and, as previously reported, the Agency experts at the site have been informed that the plant has ordered an external steam generator to meet its requirements, which would allow all six reactor units to be placed in cold shutdown. However, the installation of this equipment is not expected to be completed until the first part of next year. Ukraine's national regulator, the State Nuclear Regulatory Inspectorate of Ukraine (SNRIU), issued regulatory orders in June to limit the operation of all six units of the ZNPP to a cold shutdown state.
The ZNPP separately informed the IAEA late last week that it had decided to close the reactor vessel of unit 3 - which had been left open and was being used as a reservoir of borated water in case it was needed. Borated water is used for cooling the nuclear fuel in the primary circuit of pressurized water reactors and the spent fuel stored in pools. ZNPP has informed ISAMZ that there currently are sufficient supplies of such water on site. The IAEA supports this decision of the ZNPP to close the unit 3 reactor because it strengthens the defence in depth, improving the nuclear safety status of the unit. The ZNPP has said it has no plans to put more than two reactors in hot shutdown.
Also ahead of the winter, the IAEA was this week informed that the nine mobile diesel boilers with varying capacity of between 1 and 6.5 megawatts - installed at the ZNPP and used for district heating also during the previous cold season - are being put into service again, with eight of them currently operating.
Following the detection of minor water leaks in two of the steam generators in unit 6, earlier this month, the ZNPP has successfully completed and tested the repairs of the identified defective steam generator tubes. The testing demonstrated that there were no water leaks detected in any of the four steam generators of unit 6. The ZNPP has now started planned maintenance work on part of the unit's safety systems.
In the latest indications of military activities some distance away from the ZNPP, the experts have continued to hear explosions almost every day and they have also heard occasional machine gun fire.
The IAEA has been informed that the power supply to Enerhodar was cut for more than two hours in the evening of 18 October. It was not clear what caused the failure. This follows reports that about a week ago an electrical substation was damaged, leading to some parts of the city being left without electricity and water.
Over the past week, the IAEA team has performed walkdowns across the ZNPP site, including in the main control rooms of units 1, 3, 4, and 6, the turbine hall of unit 6, the reactor buildings of units 1 and 3, the emergency diesel generators of units 3, 4 and 6, as well as within the site perimeter. No mines or explosives were observed during these walkdowns, the team reported.
As part of these activities, the IAEA experts also continue to closely observe the performance of the operating staff as the team collects more information about the status of staffing as well as the training and licensing of staff at the plant under the Russian Federation's regulations.
Following the team's visit to the rooftop of unit 2 earlier this month, the team has continued to request access to the rooftops of reactor units 1, 5 and 6. The IAEA experts also need access to all six turbine halls together. They were, on 18 October, able to access all floors of the turbine hall of unit 3 but were only allowed partial access to the turbine hall of unit 4 on the same day.
The IAEA teams at Ukraine's three other NPPs and the Chornobyl site report safe and secure operations of these nuclear facilities despite the continuation of the armed conflict. The IAEA earlier this week conducted successful rotations of its teams at Chornobyl, and the Rivne, Khmelnitsky and South Ukraine NPPs.
The IAEA last week completed its 29th delivery of equipment and other items designed to enhance nuclear safety and security in Ukraine, providing dissolved oxygen analysers, sodium and gas analysers, as well as an oscilloscope multi-meter to the SUNPP. The equipment was procured using extrabudgetary contributions from Japan and the United Kingdom.
