FiR1 decommissioning

VTT’s FiR 1 TRIGA Mark II reactor was operated from 1962-2015 initially for neutron and reactor physics research and later for medical treatment. During its lifecycle the reactor output had been upgraded from 100 kW to 250 kW. At the end of its lifecycle, decommissioning license was granted to VTT in June 2021 by the Government of Finland. The contract on decommissioning services, signed in March 2020 between VTT and Fortum, covers the dismantling of FiR1 and all necessary nuclear waste management services.

The decommissioning project had two distinctly separate phases:

• Decommission planning and support
• Site preparation, dismantling, and waste management

The planning and support phase consisted of decommissioning site design, developing radioactive waste management process, and planning of dismantling and radiation protection. In addition, Fortum created relevant documents for operational radiation safety and work instructions for dismantling and disposing of the reactor. In addition specific waste containers and radiation shields were also developed and manufactured for the most activated waste. Fortum has also supported licensing and spent fuel management. The planning and support phase was completed in December 2022.

Site preparation and dismantling started in the beginning of 2023. Fortum’s responsibilities are site preparation for dismantling, implementation of radiation protection and waste management arrangements as well as all demolition work.

The waste management, which is carried out alongside dismantling, consists of characterization, sorting, packing, transportation and final storage and disposal at Loviisa NPP LILW repository. While the reactor dismantling is the first of a kind in Finland, this is also the first time external nuclear waste has been permitted to be disposed of at Loviisa repository.

All reactor components have predeterminate waste handling procedures. Depending on activity, nuclide vector and material, waste components are sorted into three different final disposal package types. Following the packing, waste is characterized and transported to the temporary storage area. When there is enough waste in storage for one transport, the waste containers will be packed inside of an official public road transport container. After getting an approval from Loviisa NPP organization, the waste will finally be transported to the Loviisa final disposal facility and ownership of the waste is transferred from VTT to Fortum.

The project is executed in close cooperation with VTT and Finland’s government officials. Since such a project has not been done in Finland before, the planning and documentation was created with utmost thoroughness to ensure that all stakeholders were satisfied with the progression. Fortum’s internal collaboration likewise increased as experts from Fortum Loviisa NPP, Nuclear Services, and Radiation Safety -teams all had essential parts in the project.

Fortum utilized several modern tools for planning the decommissioning. A virtual model (eSiteview) of the site was created to support remote planning. Radiation modelling (MCNP and HVRC VRdose®) has been used to optimize the work process and calculate as well as visualize radiation doses in different work phases. All reactor internals dismantling phases are modelled with 3D software (Solid Works, Micro Station etc.) to ensure smooth execution and to streamline work plans.

Fortum’s vast nuclear and radiation expertise as well as experience with on-site projects assured reliable operation with desired schedules.

Fortum has unique set of skills in Finnish nuclear field. The project could be carried through, from initial project planning all the way to final waste disposal, by a single company with wide array of services that could be utilized at different points of the project.

Alongside general decommission experience gained in the project, Fortum got a concrete improvement in the services provided – from now on Loviisa LILW final disposal site can support Finnish industrial sector with final disposal of radioactive waste.

For the planning and support phase, 25 documents have been prepared for licensing and later execution of the project. So far approximately 10 man-years have been adopted to the project.

"The FiR1 decommissioning project is the first of its kind in Finland. During the project, the authority has not had existing procedures for such projects, and planning documentation has never been taken this far before. Flexibility was also learned during the project, as support was needed from other organizations, and help has been available in both directions", says Fortum's leading decommissioning specialist Matti Kaisanlahti.

"Overall, the project is unique and new, and a lot of new things were learned during the project. Despite the large workload of the project, the overall schedule has been kept, since the goal of the project has been clear and visible from the beginning. And what's the most important, the customer has been satisfied with the operation of the project and the produced material."

With planning and preparation finished, the project continued with on-site dismantling June 2023. By the end of October, the reactor internals and primary circuit have been completely dismantled and the final disposal should be completed by 2024.