In his latests update on the situation at the Zaporizhia NPP (ZNPP), International Atomic Energy Agency (IAEA) Director General Rafael Mariano Grossi said plant management is planning to resume pumping water that still remains accessible despite a major loss of water in the Kakhovka reservoir caused by the destruction of the downstream dam earlier this month.

For the past two weeks, the plant has received the cooling water it needs from the reserves held by a discharge channel of the nearby Zaporizhia Thermal Power Plant (ZTPP). This is separate from the reservoir, whose water level has plunged since the dam was severely damaged on 6 June.

Water from this channel is used to supply the ZNPP’s spray ponds which are cooling the six shut down reactors and used fuel storage. This water also keeps a separate large cooling pond at the plant full, mainly compensating for evaporation. As a result, and in line with expectations, the channel’s water level has been declining by up to 10 centimetres a day and is currently measured at just over 17 metres. The water in this channel is still projected to provide cooling for many weeks. The IAEA team of experts at the site was informed by the plant that the ZNPP spray ponds are also replenished through pumping from a drainage system fed by underground water in the area of the ponds.

The ZNPP is now preparing to replenish the ZTPP discharge channel, either by pumping water from the ZTPP inlet channel, which was the normal practice prior to the dam damage, or from a body of water in the ZNPP port. The latter was created months ago by dredging the bottom of the port to ensure that some water was retained in case the water levels in the reservoir dropped below the level where water could be fed from the ZTPP inlet channel.

Pumping additional water into the discharge channel would give the ZNPP more time until it may be required to use the much larger cooling pond.

“Together, the large cooling pond, the smaller spray ponds, and the discharge channel have sufficient water for some months, but the Zaporizhia Nuclear Power Plant is also taking action to preserve and replenish these reserves as much as possible,” said Grossi, who travelled to the facility last week to assess the increasingly challenging nuclear safety and nuclear security situation there. “It is also exploring alternative ways of getting water.”

At the same time as the plant is grappling with such water-related challenges, the military situation has become increasingly tense amid reports of a Ukrainian counter-offensive in the same southern region where the currently Russian-controlled ZNPP is located.

Since Russia took control of ZNPP in March 2022 as part of its special military operation in Ukraine, the Russian national guard has been protecting the station and in October, Russian President Vladimir Putin signed a decree formally transferring ZNPP to Russian jurisdiction under nuclear utility Rosenergoatom (part of Rosatom). A Russian Federal State Unitary Enterprise. Zaporizhia NPP was established by Rosenergoatom to operate the plant. However, Ukrainian nuclear utility Energoatom still claims ownership of the plant. IAEA has had experts permanent stationed at the plant – the Support & Assistance Mission to Zaporizhia (ISAMZ).

Reports by Russian military analysts continue to suggest that retaking control of ZNPP is one of the main objectives of the Ukrainian counter-offensive. Russia and Ukraine have blamed each other for shelling that has repeatedly downed power lines vital to cooling the reactors, which are shut down but which need a constant supply of electricity to keep the nuclear fuel inside cool and prevent a possible meltdown. Russia and Ukraine have also accused each other of destroying the Nova Kakhovka dam on the Dniepr River, which has depleted water levels in the nearby reservoir, putting at risk cooling water for the six ZNPP reactors.

The IAEA has increased its presence at the ZNPP in order to monitor compliance with the five basic principles for protecting the plant during the military conflict that were established by Director General Grossi at the United Nations Security Council in late May. These are that there must be no attacks at or from the site, that it must not be used as a store for heavy weapons, and external power sources must be protected.

Adding to the potential dangers facing the plant, ZNPP remains dependent on a single operational 750 kilovolt (kV) power line for the external electricity it needs for reactor cooling and other essential nuclear safety and security functions, compared with four before the armed conflict in Ukraine.

The ZNPP continues to lack back-up power in case the main 750 kV line is lost again – as has happened repeatedly since the military conflict began – as the last remaining 330 kV line was disconnected nearly four months ago. The ZNPP continues to receive estimated reconnection dates, from Ukraine, which are not met. The Director General visited the 330 kV open switchyard at the ZTPP last week where he saw significant damage which was attributed to previous incidents and also remnants of what he was informed were parts of drones which targeted this area.

The IAEA is aware of reports of mines having been placed near the cooling pond. No mines were observed at the site during the Director General’s visit, including the cooling pond. However, the IAEA is aware of previous placement of mines outside the plant perimeter, which the Agency has previously reported, and also at particular places inside – which security personnel at the plant explained were for defensive purposes. “Our assessment of those particular placements was that while the presence of any explosive device is not in line with safety standards, the main safety functions of the facility would not be significantly affected. We are following the issue with great attention,” Grossi said.

“The nuclear safety and security situation at the Zaporizhia Nuclear Power Plant is extremely fragile. The loss of the Kakhovka reservoir was a catastrophe for the region as a whole and has also added to the severe difficulties for this major nuclear power plant. Now more than ever, all sides must fully adhere to the IAEA’s basic principles designed to prevent a nuclear accident. We will intensify our efforts to help ensure nuclear safety and security, while also providing assistance to the affected region in other ways,” Grossi added.

The IAEA also has permanent teams of experts at Ukraine’s other main nuclear facilities. It reported earlier this month that used fuel transports from other NPPs to the centralised used fuel storage at the Chornobyl site had begun, with the first shipment from Rivne having arrived at the site in May.

Regarding that recent transfer from the Rivne NPP to Chornobyl, the IAEA was notified in advance in line with Ukraine’s safeguards agreement and all required Agency safeguards measures and verification activities were undertaken, Director General Grossi said.

The used fuel was verified during loading into the casks and continuity of knowledge was maintained from the moment the spent fuel was placed into the casks at the Rivne NPP up to its final destination at the centralized spent fuel storage at Chornobyl where it remains under IAEA safeguards, he added.