International Atomic Energy Agency (IAEA) experts at Ukraine’s Zaporizhia NPP (ZNPP) have not yet been given access to the reactor halls of units 1, 2 & 6, IAEA Director General Rafael Mariano Grossi said in his latest update. He noted that this is hindering their ability to monitor the nuclear safety and security situation at the plant.
Following a successful rotation of IAEA experts – 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. However, ZNPP did not give permission for that access, stating that the reactor hall is “sealed”. 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.
In December 2023, the ISAMZ team was refused access to the reactor hall of units 1, 2 & 6 which was the first time that the IAEA experts had 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”, IAEA noted.
“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,” 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 & 2.
“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,” Grossi added.
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 in 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, with the leak 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 update said 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 & 4 and the main control rooms of units 1-6. 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. The flow level of water remained constant.
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.
The new ISAMZ team continues to pay close attention to the staffing situation at the plant, in particular the staff operating in the main control rooms and those responsible for maintenance of critical safety infrastructure and processes. The new team 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.
In daily reminders of the physical proximity of the conflict to the ZNPP, the IAEA experts there continue to hear loud explosions at varying distances to the plant. Since Russia took control of ZNPP in March 2022 as part of its special military operation in Ukraine, the Russian national guard, Rosgvardiya, has been protecting the station. In October 2022, 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.
Russia’s Department of Nuclear & Radiation Safety Inspections (Rostekhnadzor) at ZNPP recently reported that it had monitored compliance with federal norms and rules in the field of use of atomic energy, regulations and instructions for operating at workplaces and the operational personnel of unit 6. Representatives of the IAEA took part in the event. Rostekhnadzor said the radiation situation on the site is normal and no deficiencies affecting security had been identified.
Renat Karchaa, adviser to the General Director of Rosenergoatom said scheduled preventive repairs will be carried out in 2024 at ZNPP by specialists of Atomenergoremont and the repair division of ZNPP. "About 800 specialists of the ZNPP power repair division will be involved in carrying out repairs. Specialists of the energy department, thermal automation and measurement department of ZNPP will also be involved, " Karchaa said.
During the repair process, specialists will conduct operational control of the metal, technical inspection, serviceability and adjustment of fuses, tightness, and security systems. Rebar will be repaired. Karchaa noted that, at the moment, the state of the plant's power units is not cause for alarm. He confirmed that background radiation remains stable. "Currently, the development of scheduled preventive maintenance schedules for 2024 has been completed, and they are under consideration by the chief engineer of ZNPP," Karchaa stressed.
Image: The IAEA recently completed its fifteenth rotation of experts at Zaporizhia but have been denied access to the plant's reactor halls (courtesy of IAEA)
