Decommissioning of Otaniemi research reactor to be implemented using Finnish nuclear sector expertise

An era in Finnish nuclear power history is coming to an end with the dismantling of Finland Reactor 1 (FiR 1), commissioned in spring 1962 in Otaniemi. The dismantling project to be carried out by Fortum will be completed in spring 2024, according to the project schedule. The spent fuel has already been transported to its country of origin, the United States, and the radioactive components to be dismantled will be delivered to the Loviisa nuclear power plant’s final disposal repository for radioactive materials.

Reactor core of FIR

FiR 1, the TRIGA Mark II reactor manufactured by the US company General Atomics, started operating in March 1962. Over the decades it produced fission neutrons and isotopes for research, education, services and medical use. In its last years of operation, it was used in cancer research. The reactor was shut down permanently on 30 June 2015, and permission to dismantle it was granted in summer 2021.

Project backed by strong Finnish nuclear sector expertise

There are only a limited number of actors in the world with the expertise and capabilities needed to decommission a nuclear reactor. However, Finnish expertise in this area is cutting edge. In fact, the Finnish Fortum was selected to carry out the reactor decommissioning work. Fortum and VTT signed an agreement on the reactor decommissioning in 2020. The scope of the work covers planning and implementing the reactor’s decommissioning, as well as the packaging and final disposal of the dismantling waste.

“With our decades of nuclear power experience, we have the know-how and the resources to perform these types of assignments cost-effectively and safely,” says Antti Ketolainen, Senior Manager, Decommissioning and Waste, Fortum Nuclear Services.

Empty reactor.

Good planning enables safe work

At some two meters in diameter and six meters high, FiR1 is significantly smaller in size and less radioactive compared to nuclear power plants, but its dismantling has required meticulous planning. In fact, thousands of work hours have gone into planning, permitting and authorisation processes.

“Good planning enables the smooth and safe implementation of the actual dismantling work. We have had a team of the sector’s top professionals working on the project, so we’ve been able to take into account everything needed for the project. The 700+ pages of documentation in use are reflective of this,” says Tero Repo, Fortum’s Project Manager for the dismantling work.

The project’s nearly 10-month-long dismantling phase is planned to be divided into seven stages. The first stage is site preparation, which includes radiation protection work and preparation for the various dismantling stages. Stage two includes the dismantling of the reactor’s internal parts, such as the control rods, the rotary specimen rack and the reflector.

The next stage involves the dismantling of the primary circuit and the water purification circuit, as well as the dismantling of the BNCT cone structure used in radiation treatment. These stages will be followed by the dismantling the active parts of the two-meter-thick concrete shell by wire sawing. The next step will be to dismantle the secondary systems, like pipelines, dry storage silos, argon systems and tanks, and the final clean-up of the site.

The reactor is located below the observation room.

Spent fuel to the United States – the reactor’s radioactive components into the bedrock in Loviisa

The research reactor fuel has already been returned to the USA, its country of origin, by VTT. The return of the fuel was made possible by an exemption in the Finnish Nuclear Energy Act for research reactors. Fortum assisted VTT in the transport arrangements for the return.

As for the reactor’s radioactive dismantled material, it was agreed that it will be deposited in the Loviisa nuclear power plant's final disposal repository for low- and intermediate-level radioactive waste, which is eventually where also the Loviisa nuclear power plant’s components will be placed when the plant reaches the end of its lifetime.

Waste from decommissioning work is carefully packed in dedicated containers.

The bottom of the reactor is prepared for decommissioning.

Hydraulic scissors that are used to cut even the hardest materials.

ISOCS meter, used to measure radioactivity, positioned next to the reactor.