International Atomic Energy Agency experts at Ukraine’s Zaporizhzhya Nuclear Power Plant (ZNPP) have not yet been given access to the reactor halls of units 1, 2 and 6, hindering their ability to monitor the nuclear safety and security situation at the plant, as well as the five concrete principles established at the United Nations Security Council, IAEA director general Rafael Mariano Grossi said on 12 January when reporting the IAEA’s latest Ukraine Update, No 205.
Following a successful rotation of IAEA experts on 11 January – the fifteenth team of experts to arrive at the plant since the IAEA Support and Assistance Mission to the ZNPP (ISAMZ) was established in September 2022 – the new team repeated the request for access to the reactor hall of unit 6.
The ZNPP did not give permission for that access on the day, stating that the reactor hall is “sealed”. The ZNPP informed the team that it was not denying access, and has instead proposed that the team access the area in about a week’s time.
Restricted access
In December 2023, the ISAMZ team was refused access to the reactor hall of units 1, 2 and 6 which was the first time that the IAEA experts have not been granted timely access to a reactor hall that was in cold shutdown. Until then, all ISAMZ teams had been able to access the reactor hall of any unit in cold shutdown, without the plant making any reference to the status of containment as being “sealed”.
“These restrictions on the experts’ timely access to the ZNPP are impeding the IAEA’s ability to assess the safety and security situation, including confirming the reported status of the reactor units, spent fuel ponds and associated safety equipment, independently and effectively,” director general Grossi said.
Also, since 18 October last year, ISAMZ teams have been unable to access parts of the turbine hall of each unit. Most recently, access was again restricted at the turbine halls of units 1 and 2 on Wednesday, 10 January.
“The nuclear safety and security situation remains very precarious, and I reiterate my request for unhindered access so that the IAEA can assess the Seven Pillars for nuclear safety and security and monitor adherence to the five concrete principles to help ensure nuclear safety and security at the ZNPP in order to prevent a nuclear accident and ensure the integrity of the plant,” Director General Grossi added.
New team to inspect maintenance situation
The new team of IAEA experts will observe the ongoing maintenance situation at the ZNPP. Following observation of deposits of boric acid on the valves, a pump and on the floors of several of the safety system rooms of unit 6 on 22 December, the IAEA team conducted a follow-up walkdown on 9 January to assess the status. Borated water is used in the primary coolant to help maintain nuclear safety functions. Although leaks may occur, prompt investigation, repair, and clean-up are crucial to prevent further damage and avoid any impact on safety.
During its walkdown, the team noted a significant reduction in boric acid deposits compared to the December 22 walkdown, with the leak also considerably diminished. However, some deposits persisted in three rooms of the unit 6 containment building, one at the same level and two showing significantly reduced levels.
The team was informed that the cause of the leak was due to micro-cracks in the boron tank due to ageing, and a blockage in the leak detection pipe. Whilst the blockage has been repaired, some smaller leaks persist as a result of the micro-cracks in the boron tank. The ZNPP stated that the leak rate is currently within technical specifications, and that the micro-cracks can be repaired after draining the tank, which will be addressed during scheduled maintenance. The IAEA team will continue to monitor the situation.
Additionally, this week the IAEA experts at the ZNPP accessed the pumping stations for units 3 and 4 and the main control rooms of units 1 to 6. All nine mobile diesel boilers installed at the plant were utilised during the past week to provide additional heating needs during winter.
As the winter weather gets colder, IAEA experts reported that the ambient temperature at the ZNPP has dropped as low as -10°C in the mornings. The team reported that this fall in temperature had no impact on the operation of the 11 wells providing cooling water for the sprinkler ponds used for reactor cooling and other nuclear safety and security functions.
Five of the ZNPP’s six reactors remain in cold shutdown, while unit 4 is in hot shutdown to produce steam and heat, including for the nearby town of Enerhodar, where most plant staff live.
New boilers
The new team of experts has conducted a walkdown of the site including the four new diesel boilers. They observed the new equipment and were informed that the installation has been completed and commissioning activities have commenced. These new diesel boilers are intended to generate steam to meet the ZNPP’s needs.
Proximity of the ongoing war
The visiting experts did continue to hear loud explosions at varying distances to the plant during their visit. At the Khmelnitsky NPP they were required to take shelter several times over the weekend of 6 and 7 January. The teams at the Rivne and South Ukraine NPPs were also required to take shelter on 6 January. At the Chornobyl site, the team reported hearing explosions in the distance throughout the past week.
The IAEA teams at the Rivne, Khmelnitsky, South Ukraine nuclear power plants (NPPs) and the Chornobyl site continue to report that nuclear safety and security is maintained despite challenges related to the multiple missile attacks on Ukraine in the past week.
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