FINLAND | RADWASTE MANAGEMENT


The vehicle, which weighs more than a hundred tonnes, will initially be remotely controlled underground. The goal is to make it move autonomously along optimal routes without touching any walls, and for it to stop when it encounters an unexpected obstacle


supplier of the disposal facility, as well as its end user once it is complete,” Stenfors explains. The canisters are massive containers with a nodular cast


iron insert and a copper shell. Around 2800 canisters will be required to dispose of the spent nuclear fuel from the four operational power plant units and the fifth unit currently being commissioned. The final disposal operations will continue for around a hundred years.


Strict safety requirements and limited space Very strict safety requirements had to be considered in the KSAA’s design. Posiva had to meet thousands of rows of safety requirements, and dozens more listed in the Regulatory Guides: Nuclear Safety (YVL) publication of the Finnish Radiation and Nuclear Safety Authority. This is because the vehicle is a nuclear safety classified system (SC3).


The starting point for handling the canisters is single


failure tolerance. This means that the safety of the canister must not be compromised if any single component fails, and it must be possible to restore the canister to a safe state.


During transport, the canister will be kept inside a


radiation shield, which isolates it and protects the people who work close to the device. According to the plans, there will be more than a hundred deposition tunnels with a total length of approximately 42km. These will cover an area of around 3 km2


. Another


major challenge has been adapting the device and assuring its functions in the limited space available underground. Safety is further improved by KSAA’s electric transmission


system. The battery pack does not emit exhaust fumes, so people working in the tunnel will not be exposed to them. Fuel tanks are also unnecessary, which reduces the risk of fire.


According to Stenfors, the battery pack is ground-


breaking, because it has been approved for use in the underground deposition process. The battery chemistry has been selected with fire safety as a key attribute; as a result the risk of severe battery fire is practically non-existent. The battery pack has also been designed so that the vehicle can complete the entire canister deposition cycle with one charge.


The vehicle, which weighs more than a hundred tonnes, will initially be remotely controlled underground. The goal is to make it move autonomously along optimal routes without touching any walls, and for it to stop when it encounters an unexpected obstacle. However, a person will still monitor the device from the control room. “We want to increase the facility’s degree of automation in other ways as well. If we can reduce the required person-


www.neimagazine.com | May 2021 | 33


years throughout the hundred years of operation, we will achieve major savings for Finnish society at large, because increased production costs will directly influence the price of electricity,” Stenfors says. According to Stenfors, the device as a whole represents


a major innovation because it had to meet so many demands and would work in such a limited space. “We are making industrial history, because we are the


first to create a device for such a small underground space with such strict requirements,” he says.


Innovation Another innovative aspect of the KSAA device as a whole is that it has an ‘ innovation chain’ that includes all the main functions. It is like a Transformer, in that it can move its own components and modify itself for different functions while on the move. The detailed design phase for the equipment and the


project will be completed in summer 2021. COVID-19 made the design project even more challenging. However, engineers were able to work remotely to complete examinations of the 3D model and attend other project meetings, according to Stenfors. He adds, “The cooperation with Finnish consultant


companies has been very fluent. Indeed, I’m amazed by the pace and energy of all the companies during this project. I will tip my hat to them if they can keep up the same pace until the end. On the other hand, this project is a showcase for the global nuclear industry.” Posiva’s equipment programme has now proceeded


to the detailed design phase, which is estimated to be completed in summer 2021. Meanwhile the company’s commercial subsidiary Posiva Solutions provides tailored expert services using all the company’s know-how. The expertise offered is based on Posiva’s decades-long experience in design, research and development of final disposal of spent nuclear fuel in Finland and we believe Posiva Solutions can add value to national nuclear waste management programmes by saving time and cost. ■


Below: 3d-model of the canister transfer and installation vehicle (KSAA) equipment Photo credit: Posiva


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