Ukraine’s Zaporizhzhya Nuclear Power Plant (ZNPP) is preparing to once again use reactor unit 4 to generate steam for various safety functions at the facility, following repairs that put it out of action for several weeks, Director General Rafael Mariano Grossi said today.

 

After the plant conducted hydraulic pressure tests on the primary and secondary cooling circuits of this unit, IAEA experts at the site said the ZNPP this week began transitioning it from cold to hot shutdown. Once this is done, the ZNPP plans to return unit 6 to cold shutdown. Unit 6 has been providing steam in hot shutdown since mid-August, after a water leak was detected in one of unit 4’s four steam generators.

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While unit 4 was in cold shutdown, the ZNPP identified that the cause of the water leak was a hairline crack in the weld of the steam generator’s primary header vent pipe, which has now been repaired and tested. 

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As previously reported, Ukraine’s national regulator, the State Nuclear Regulatory Inspectorate of Ukraine (SNRIU), has issued regulatory orders to limit the operation of all six units to a cold shutdown state. In addition, the IAEA has been strongly encouraging the ZNPP to find an alternative source of steam generation to cover the plant’s needs, including for processing liquid radioactive waste, and allow for all its six reactors to be maintained in a cold shutdown state.

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The IAEA experts were informed this week that the ZNPP had ordered the equipment needed to generate enough steam to meet the site’s requirements. The installation of this equipment is expected in the first part of next year, provided there are no supply chain delays, the ZNPP said.

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“The IAEA has repeatedly been calling for an alternative steam solution so that all six reactors can be put in cold shutdown, as instructed by Ukraine’s regulator. I hope that the plant will implement this change as soon as possible,” Director General Grossi said.

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In the latest indications of military activities some distance away from the ZNPP, the experts continue to hear explosions almost every day and have also heard machine gun fire, highlighting the risks to Europe’s largest nuclear power plant (NPP) during the military conflict in Ukraine.

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The IAEA team is continuing to look at the situation regarding ZNPP staffing, which has declined significantly since the beginning of the conflict and remains complex and challenging. This week, the IAEA experts have been gathering further information, including visiting main control rooms and the training centre where they discussed training and licensing.

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As part of their walkdowns over the past week, the IAEA experts visited the turbine hall of unit 6, observing no military equipment there. The team noted during a walkdown within the site perimeter that some of the mines previously observed had been removed while some work was being performed on the interior fences.

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The IAEA team is continuing to request access to all six turbine halls, one after the other, to be able to confirm the absence of any materials and equipment that may contravene the five concrete principles for the protection of the ZNPP.  So far, this request has not been approved and the team can only confirm the status of one turbine hall at a time.

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The IAEA experts are also continuing to request access to the rooftops of reactor buildings 1, 2, 5 and 6, which they had expected to be granted last month. The IAEA is now awaiting approval for such access next week.

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“As I have said repeatedly in recent months, we will continue requesting the access we need to implement our important mission, including for monitoring compliance with the five concrete protection principles designed to prevent a nuclear accident at the site,” Director General Grossi said.

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Regarding the site’s water situation, the IAEA experts said the ZNPP had completed drilling another groundwater well to supply the site’s sprinkler ponds used for reactor cooling and other nuclear safety and security functions, bringing the total to 11 new wells as part of efforts to find alternative sources of water following the destruction of the Kakhovka dam almost four months ago.  

 

The 11 wells are supplying around 250 cubic metres per hour, which the site had estimated would be sufficient to maintain the level of all 12 sprinkler cooling ponds.

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However, the IAEA experts observed during a walkdown on Wednesday that the level of water in three of the ponds had fallen since the previous visit a few days earlier. At the time, the site was re-plenishing the three sprinkler ponds to return the water levels to normal. Today, the team conducted another walkdown of the sprinkler ponds and confirmed that the water levels of all ponds were within the operational limits. The IAEA experts are looking into the cause of the temporary water decline.

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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 conducted successful rotations of its teams at Chornobyl, and the Rivne, Khmelnitsky and South Ukraine NPPs earlier this week.

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The IAEA today completed its 25th delivery of equipment and other items designed to enhance nuclear safety and security in Ukraine, providing medical equipment and consumables to the Chornobyl site. This delivery was made possible using extrabudgetary contributions from the European Commission.

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Separately, the second delivery of spare parts and rubber products for the emergency diesel generators of the South Ukraine NPP, envisaged under arrangements agreed on 5 May between the IAEA, France and Ukraine’s Energoatom, arrived at the site this week. These spare parts are essential for the maintenance and functionality of the diesel generators, ensuring they would work if the site were to lose off-site power. The first delivery took place in June.

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In total, the Agency has now facilitated deliveries of nuclear safety and security equipment of more than 6.8 million euros to different organizations in Ukraine since the start of the armed conflict as part of its overall assistance programme.

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-  Text, IAEA -