Extensive design work pays off: the canister installation device is ready
Four years of work has produced a result. A prototype of the canister installation device arrived in Olkiluoto in May.
The completely Finnish-designed and Finnish-made device will be used to test the placement of disposal canisters in deposition holes bored in the bedrock. The device incorporates various types of precision mechanics. Complete with a canister, it weighs no less than 103 tonnes. The device’s multiple safety features are the result of careful design.
The first sketches of the canister installation device were drawn approximately four years ago. In addition to two Turku-based engineering offices, several Posiva and TVO experts whose fields ranged from quality assurance to technology and commerce took part in the design and manufacturing phases.
“Investing in development work enables us to achieve savings through lower tunnel excavation and backfilling costs in the final disposal phase. The dimensions of the device are optimised with those of the tunnel. Other features that we have particularly focused on include availability, precision and safety,” says Posiva’s design engineer Jouni Tiainen.
The purpose of the canister installation device is to enable the disposal of spent nuclear fuel, enclosed in canisters, in special deposition holes bored in the Olkiluoto bedrock. According to the plan, the device will be used to transport the canisters from the interim storage, located more than 400 metres below the ground surface, to the deposition tunnel. Additionally, the device will be used to place the canisters in deposition holes lined with bentonite clay with an accuracy of 10 millimetres.
The canister will be transported inside a radiation shield located at the middle of the device. The shield will protect the canister from any rocks falling from the tunnel ceiling and reduce radiation levels in the vicinity of the canister. The safety features prevent the canister from falling down during the transfer and installation. This is ensured in several ways, one of which is that the friction caused by the canister loaded onto the device prevents the opening of the gripper mechanism holding the canister.
The canister installation device was manufactured in Pori. The manufacturing phase lasted for over two years. The device was brought to Olkiluoto in May. The testing will begin in the autumn. If required, the device will be developed further on the basis of the test results. The prototype to be tested will thus be used as a basis for the final version of the device, which will be constructed before the commencement of the final disposal operations in the early 2020s.