On Sunday, September 6, Babcock Noell GmbH (BNG) completed a remarkable stage in the construction of the Olkiluoto 3 power station in Finland. After the most spectacular piece of transportation work in the history of the BNG company in just four days across the Baltic Sea, the Würzburg-based specialists lifted the roof, or the so-called dome for the containment liner, into place in the early hours of Sunday morning, making it the last part on the containment liner.

After the dome had been made ready for lifting at the preassembly yard, the weather on Sunday played its part. In perfectly calm conditions the SARENS heavy lift crane lifted the 200 t part, which has a diameter of 47 m and a height of 15 m, slowly through the still air and finally set it down with millimeter precision almost three hours later in its final position on the cylindrical part of the containment liner. The lifting cables were detached four hours later after the dome had been secured with bolts.

Engineering work started back in the autumn of 2006, with the actual assembly of the dome starting just a year later in the harbor at Gdynia (Poland). It had been decided that separate preassembly of the complete part, including transportation by sea, was preferable to the considerable work and effort involved in assembling the dome on site. An international team of specialists ensured that all the work was completed without a hitch.

The calculations for the dome were particularly challenging. For example, a special substructure had to be made for handling and transportation, one which would provide guaranteed stability during assembly and transportation across the Baltic. Similarly, the high dimensional accuracy of 1/1000 was also a major challenge.

A further notable feature of the dome is its inherent stability after setting down on the cylindrical shell. The 1 ½ m thick outer layer of concrete can be set down directly on the steel shell later without any further support and formwork.

Background: Olkiluoto 3 nuclear power station

The Olkiluoto nuclear power station, where the part has been installed, is being built by the French-German consortium comprised of AREVA NP and Siemens AG. It is the first contract worldwide for the construction of a third generation pressurized water reactor from the Finnish power supply company TVO (Teollisuuden Voima Oy). It is planned that the power station in Olkiluoto is to start commercial operations in 2012 alongside two existing power station blocks. With an output of about 1,600 MW it will then be one of the most productive stations in the world. An even higher standard of safety is also to be achieved with this new type of power station.

In addition to the containment liner for this latest new generation of power station, Babcock Noell also delivered other safety-related parts, such as the personnel air-locks.