The International Atomic Energy Agency (IAEA) deployed additional staff to Ukraine’s Chornobyl (NPP) to conduct a comprehensive safety assessment of the damaged New Safe Confinement (NSC) following a drone strike last February, at the request of the State Nuclear Regulatory Inspectorate of Ukraine (SNRIU).
Staff from the IAEA’s Department of Nuclear Safety and Security joined the IAEA’s Support and Assistance Mission to Chornobyl, which has been continuously present at the site since January 2023. Their objective was to evaluate the current condition and operational status of the NSC.
The NSC, completed in 2016, is a protective structure built to enclose the Shelter Object (sarcophagus), which was built to cover the remains of unit 4 that was destroyed in the 1986 accident. Although the drone strike did not lead to any release of radioactive material, it caused significant structural damage, affecting the NSC’s designed confinement function and projected lifetime. The IAEA team reviewed the measures currently in place to mitigate risks and discussed the plant’s plans to restore the NSC’s functionality.
The mission confirmed that the NSC had lost its primary safety functions, including the confinement capability, but also found that there was no permanent damage to its load-bearing structures or monitoring systems.
“Limited temporary repairs have been carried out on the roof, but timely and comprehensive restoration remains essential to prevent further degradation and ensure long-term nuclear safety,” Director General Grossi said.
Based on the mission findings, the IAEA recommended further restoration and protective work of the NSC structure, including humidity control measures and an updated corrosion monitoring programme, as well as an upgrade of an integrated automatic monitoring system for the shelter object structure built on top of the reactor immediately after the accident.
In 2026, with support from the European Bank for Reconstruction and Development (EBRD), the Chornobyl site will undertake additional temporary repairs to support the re-establishment of the NSC’s confinement function, paving the way for full restoration once the conflict ends.
According to Chernobyl NPP (ChNPP), the drone attack caused damage to the integrity of the NSC’s outer cladding and a prolonged fire, which significantly damaged the Arch’s inner sealing membrane.
Damage to the sealing cladding led to:
- non-compliance with the design requirements for the tightness of the main protective structure and its function as a barrier that prevents the spread of radioactive substances into the environment;
- rendering proper airflow control impossible in accordance with the design and technological requirements necessary to maintain the required air pressure/vacuum in the NSC space; and
- violation of the requirements for preventing atmospheric precipitation from entering the NSC space.
However, the radiation level at the Chornobyl industrial site remains stable and within the established limits.
ChNPP noted that the IAEA experts confirmed the loss of some of the NSC’s key safety functions, including its containment capability but did not find any irreversible damage to the supporting structures or monitoring systems.
In October, ChNPP completed work to eliminate the opening in the outer cladding of the confinement. “In order to fully restore the NSC functioning it is necessary to implement a set of measures, including the replacement of the sealing membranes ensuring a tight connection between the Arch and the concrete structures of the ChNPP and the NSC, as well as the restoration of the full tightness of the outer cladding. This is a complex technical task, given the high levels of radiation in the area where the work is being carried out”, said ChNPP General Director Serhii Tarakanov.
He added that the European Bank for Reconstruction & Development (EBRD) had engaged experts from the French companies Bouygues Travaux Publics and VINCI Construction Grands Projets, members of the Novarka consortium, which designed and built the NSC. The experts are conducting a comprehensive study of the technical condition of the Arch’s structures and technological systems, identifying current and long-term risks, the scope of necessary restoration work, and formulating recommendations on the policy and strategy for NSC restoration.
