Bioshield demolition at Barsebäck and Oskarshamn nuclear power plants in Sweden

Between 2022 and 2025, I was involved in a nuclear power plant demolition project. The target consisted of four so-called biological shields, which in this case were reinforced concrete cylinders approximately 15 meters high, with a wall thickness of 1.5 meters and a diameter of 9 meters. The purpose of the cylinder is to protect the environment from the radiation emitted by the nuclear reactor. The mass of each cylinder is approximately 1,500 tons. The demolition contractor was Lodab Demolering AB, and I was their subcontractor handling the duties of an HSE coordinator. In practice, I shared the project management responsibilities with Lodab's Site Manager, Mika Myntti.

The project encompassed the exact same work across a total of four units: BKAB 1 and 2, as well as OKG 1 and 2. The first three were identical in structure, but the last one was built before the others and was smaller, yet structurally more difficult to demolish and had higher radiation levels.

Safety was of paramount importance in these, as in other demolition works. The risks related to the actual demolition work, lifting operations, working at heights, and other similar factors were prepared for normally, but naturally, radiation safety is a factor that does not need to be worried about on traditional demolition sites. In addition to radiation safety, dust control was perhaps a bit stricter than in other demolition works due to the facility's controlled ventilation. All air is directed out through the chimney, where filters are analyzed for both radiation and impurities. The maximum permitted personal radiation dose per year is 20 mSv, but the limits set internally by the plants are about 25% of this. Even though we tried to avoid it, the demolition work still involved working in the immediate vicinity of the bioshield, where the inside of the cylinder, particularly midway up vertically, was the worst place in terms of radiation.

As the work progressed, we learned and developed methods that significantly reduced the working time in these areas. This was necessary not only for personal safety but also for purely practical reasons, because if the personal radiation dose limit set by the client was exceeded, the worker in question would be barred from the site for the rest of the year.

The demolition work was carried out by wire sawing. Before sawing, hundreds of holes were drilled through the cylinder according to the cutting plan for both the lifting chains and the wire. Depending on the location, pieces weighing between 5 and 35 tons were sawn from the concrete cylinder, which were then sawn during secondary segmentation along boundaries defined by the client into different waste categories based on their radiation level. For our part, the limit of our contract was packing the pieces into sea containers, which the client took to final disposal. This was a very interesting project that taught me a lot not only about radiation safety but also about operating in a shared international workplace and, for example, the safety of lifting operations and dust control.

References

City of Lahti

• In cooperation with Käpylän Monipalvelut Oy: Asbestos and hazardous materials surveys, demolition material surveys, and reuse studies for the Nastola town hall and a few schools

Studio Kallio Oy / Caverion Suomi Oy

• HSE Supervisor duties at a data center substation construction site

Raahen Satama Oy

• expert services for the preliminary study project of demolition technologies and methods for steel structures

Purku Keinänen Oy

• contract estimation services
• project manager duties for the demolition of a 150-meter-long utility passage/bridge crossing a busy street

Kruunuasunnot Oy

• asbestos and hazardous material surveys, demolition material assessments for a residential building to be demolished, as well as site supervision and safety coordination during the demolition project
• Lakiala Depot: Supervisor and safety coordinator duties for the multipurpose building demolition project

Fortum

• preparation of demolition plans and work instructions for specific sections of nuclear power plants
• supervision of demolition work related to a nuclear power plant demolition contract

Caruna Oy

• asbestos and hazardous material surveys, demolition material assessments, and developer consulting for an electrical facility (3 buildings) to be demolished

ISS Palvelut Oy

• project manager duties for the demolition of an old paper mill steam power plant
• current operating environment is a data center

Ytekki Oy

• collaboration and subcontracting related to demolition surveys and developer consulting tasks