The HAEA has authorised the continuation of certain construction activities in the entire area of the Unit 5 working pit of the Paks Nuclear Power Plant

On 19 June 2025, the Hungarian Atomic Energy Authority (HAEA) authorised the Paks II Nuclear Power Plant Ltd (Paks 2) to continue the construction activity prohibited by the decision issued under P2-HA00759. The reason for the earlier prohibition, which was imposed in order to ensure the stability of the retaining walls of the working pit and to eliminate the life-threatening condition, was that on 30 January 2025, a localized collapse of a part of the improved soil wall and the detachment of the soil improvement block occurred on the southern wall section of the working pit of Unit 5.

The HAEA, as the general building authority, following an on-site inspection, immediately halt Paks 2 from work on the collapsed section of the southern wall of the pit and the areas of the pit at risk of collapse, inter alia, to avoid immediate danger to life. The HAEA subsequently ordered Paks 2 to review the stability of the walls of the entire pit and to reinforce the stability of the parts considered potentially dangerous.

Paks 2 was ordered to eliminate the irregular situation and to prepare and submit documentation on the review and verification of the stability of the retaining walls and to detail the methods and activities to be undertaken in order to predict similar situations that could threaten life and work safety.

In the period after 30 January 2025, Paks 2 has carried out a review of the condition of the retaining walls of the working pit, identification of potentially hazardous zones and the removal of damaged, unstable parts where risks of similar failure have been identified have also been completed. Preventive soil nailing was carried out in the sections at risk.

On 22 April 2025, Paks 2 submitted the verification of implementation of the required obligations and activities, and at the same time applied for the authorisation to proceed with the construction activity. The HAEA assessed the submitted documents and carried out an inspection on 12 June 2025 to verify the implementation of the measures specified by Paks 2.

Based on the submitted documentation, the on-site inspections carried out in the meantime, the HAEA has issued a decision allowing the continuation of construction activities on the affected sections.

In order to ensure the long term safe working conditions, the HAEA ordered the licensee to construct a rockfall grid on the affected sections of the retaining walls and to complete the condition assessment work programme.

During construction, continuous monitoring activities must be carried out to monitor and document the ground water level and the movement of the retaining walls of the working pit and of the surrounding buildings.

The monitoring systems did not indicate any further movements in the excavation pit, however, in order to better predict similar movements in the future and to allow for timely implementation of possible preventive measures, the HAEA has also required the review of the intervention and notification levels of the monitoring system.

Other activities, such as the pouring of the first concrete, may only commence once the conditions and hold points set out in other HAEA permits have been met and accepted.

The adequacy of the soil improvement is assessed by the HAEA in a separate procedure.

The decision on the measures to be taken can be found here. The notice of the decision authorising the continuation of the construction activity can be downloaded here, and the decision can be accessed here.