Information Notice

Information Notice of the Hungarian Atomic Energy Authority Concerning the “First Concrete” Pouring of the Nuclear Island of Unit 5 at the Paks Nuclear Power Plant

The term “first concrete” originates directly from the terminology used by the International Atomic Energy Agency (IAEA), which provides an internationally recognized framework covering the entire lifecycle of nuclear power plants—from design through operation. In the IAEA’s Power Reactor Information System (PRIS) database, which stores data on nuclear power plants worldwide, the official start date of construction of a facility is recorded as the date when the first concrete is poured for the foundation slab of the reactor building (the nuclear island).

Based on this definition, the term “first concrete” refers exclusively to the initial concreting of the foundation slab—the deepest and thickest structural element—of the nuclear island, including the reactor building. Earlier works, such as levelling concrete pouring, soil stabilization, or working area preparation, are considered part of the preparatory phase. According to IAEA standards, a plant is not formally considered “under construction” during these preparatory activities.

Under the national regulatory framework, no separate “first concrete permit” exists, the start of the pouring marks the completion of a complex licensing process and a set of technical prerequisites. On 25 August 2022, the Hungarian Atomic Energy Authority (HAEA) issued the construction license for Units 5 and 6 to be built at the Paks site, creating the legal basis for obtaining individual building permits for the associated infrastructure and structures.

Parallel to the construction licensing procedure, and in accordance with the legal framework, it was possible to authorize certain site preparation works (such as soil improvement, cut-off wall construction, and soil excavation) in advance. The risks related to these works were borne entirely by Paks II Ltd., as the licensee.

On 30 December 2021, Paks II Ltd. submitted applications for building permits for the nuclear island structures of Unit 5. According to the design, the Reactor Building, Auxiliary Building, Steam Cell, Safety Building, Control Building, and Switching Chamber will be constructed on a common foundation slab. The HAEA granted the related building permits for these structures on 30 August 2022.

The building permits established so-called hold points, the fulfilment of which was a prerequisite for starting the concreting of the foundation slab. These hold points required the submission of detailed design-level technical substantiations, including the waterproofing solution of the foundation slab, the qualification of structural materials, as well as detailed structural and seismic dynamic analyses. Beginning in the fourth quarter of 2024, Paks II Ltd. submitted the required documentation for the five buildings in multiple stages.

Furthermore, the HAEA stipulated that, beyond closing the above hold points, the approved activities could only begin after obtaining the partial occupancy permit for the soil improvement beneath the nuclear island of Unit 5. This condition was met on 4 November 2025, when the HAEA issued the necessary permit, confirming that the completed soil improvement meets the intended design function.

According to the project schedule, construction of the common foundation slab commenced with the section beneath the Control Building. Prior to this, on 11 November 2025, Paks II Ltd. began implementing the levelling concrete structure in the area, which was followed by waterproofing, rebar installation, and other preparatory works not directly involving the concreting of the foundation slab. These activities were continuously supervised by the HAEA through on-site inspections.

Based on the review of the submitted documentation, the HAEA released the hold points related to the concreting of the foundation slab beneath the Control Building in two stages—on 19 December 2025 and 26 January 2026. With this, the technical and administrative prerequisites within the HAEA’s competence for the “first concrete” pouring—together with the occupancy permit for the soil stabilization—were fully met.