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Virtual model supporting the design, construction and operation of encapsulation and final disposal facilities for nuclear fuel


Nuclear fuel encapsulation and final placement facilities (Olkiluoto, Eura River)


Posiva Oy, in the final placement plant project Sweco served as a sub-consultant of Kalliosuunnittelu Oy


Structural engineering, BIM coordination and VDC services, such as VirtualSite™

Posiva is building the world’s first nuclear fuel encapsulation plant and related underground final disposal facilities in Olkiluoto. Sweco is responsible for the project’s structural engineering and information model coordination. The design and construction processes are supported with Sweco’s VirtualSite virtual model, as will be the maintenance of the plant in the future.

Posiva is building the world’s first encapsulation and final disposal plant for spent nuclear fuel by the Eura River. The spent nuclear waste will be stored at a depth of roughly 400 metres in copper capsules, the final placement of which will begin in the 2020s. A driving tunnel and four vertical shafts are being built in the final placement facilities inside the bedrock. The tunnels are designed to last more than a century.

Sweco is responsible for the structural engineering of both the aboveground encapsulation plant and the underground final placement facilities built into the bedrock. The overall project will be designed and planned further as the implementation progresses.

“The structures and loads of the encapsulation plant are similar to those at other heavy industry sites, but there are plenty of safety-classified structures. This raises the quality level of the designs,” says Senior Structural Engineer Anssi Mäntynen from Sweco.

Every design solution and construction phase is documented carefully. One of the most challenging aspects was designing the acid-resistant steel cladding of the processing chamber of the encapsulation plant. “The structural solution proposed by Sweco is top-of-the-line in terms of technology, and their know-how is impressive,” comments Unit Manager of Structural Engineering Juha Matikainen from Posiva.

Facilities designed inside a virtual model

Due to the uniqueness of the site, the accuracy and details of the combination information model have been taken to a clearly higher level than usual. “The design and realisation information will also be updated as the worksite progresses,” says BIM Coordinator Antti Hämäläinen from Sweco. Every installation is planned carefully. “This enables us to avoid schedule delays and additional expenses.”

The combination information model has been refined into an even more detailed virtual model with Sweco’s VirtualSite™ tool. “The model includes tens of kilometres of tunnels, as well as all the HPAC, electricity and structure solutions,” Hämäläinen says.

Posiva wanted all parties to have access to virtual tools in order to facilitate assessing and developing the designs through trials instead of just by seeing them. “Sweco has boldly introduced new tools and possibilities that I would not have even known to ask about,” Matikainen comments.

The nuclear waste encapsulation process is animated in the virtual model step by step, which has been helpful in tasks such as adjusting the operation of cranes. The illustrative virtual model has also proven its usefulness in the design and construction of a 450-metre passenger lift shaft. “In the virtual model, installation solutions can be examined in the correct scale, which improves work safety when installing a steel shaft as tall as a skyscraper,” Hämäläinen says.

Digital twin supporting the operation of the plant for more than a century

The information model will be developed throughout the entire construction process with the idea that all the information contained therein will be useful in the operation of the plant. The VirtualSite model is already being used in maintenance planning and safety inspections. “Navigating the model makes it easier to identify risk areas that require procedures such as installing falling protection,” Hämäläinen comments.

In the coming years, the digital version of the plant – also known as its digital twin – will serve as a user interface for many kinds of information. “An up-to-date information model of the building is always useful when the plant undergoes change work,” Hämäläinen says. The model enables users to see with one click what kind of technology is hidden behind a certain wall or when a certain device was installed. “The model can also be complemented with sensor data regarding the conditions of the facilities, such as air humidity and temperature.”