Machinery and equipment
Posiva’s unique final disposal project requires completely new types of machinery and equipment designed for specific purposes. Several experts from Posiva and TVO, as well as other organisations, took part in the development and construction of the prototypes. The testing of the machinery and equipment prototypes at Olkiluoto will take place both above ground and under actual disposal conditions in ONKALO’s underground demonstration facilities.
The boring rig will be used to bore the deposition tunnels. Using the rig, it is possible to prepare a boring plan for each round and verify the success of the boring operation. Furthermore, the boring rig’s software enables the preparation of charging plans for each round. The rig is 15.5 metres long, 3.5 metres high and 2.5 metres wide. It weighs 30 tonnes. The boring is performed electro-hydraulically. The rig is completely computer-controlled.
Canister hole boring device “Sanna” (prototype)
The canister hole boring device “Sanna” will be used to bored deposition holes – with a diameter of approximately 1.8 metres and a depth of some 8 metres – in the Olkiluoto bedrock. First, the device bores a 30-centimetre pilot hole, which is then broached out to its full size. The deposition holes are bored in solid bedrock from above.
Bentonite buffer installation device (prototype)
The buffer block installation device will be used to install buffer blocks made from compressed bentonite clay into the deposition hole. The blocks protect the canister. The installation device lifts the 2–3,5-tonne buffer blocks by means of vacuum suction. The fully power-operated installation device will be transferred to the deposition tunnel using a terminal tractor and then positioned precisely on top of the deposition hole with the help of automatic laser measurement equipment.
Canister transfer and installation vehicle (prototype)
The purpose of the canister installation device is to enable the disposal of spent nuclear fuel, enclosed in canisters, into special deposition holes bored in the Olkiluoto bedrock. According to the plan, the device will be used to transport canisters from the interim storage facility located more than 400 metres below the ground surface to the deposition tunnel. Additionally, the device will be used to place canisters in deposition holes lined with bentonite clay to within an accuracy of 10 millimetres.
Tunnel backfilling device (prototype)
The backfill installation device will be used to backfill the spent nuclear fuel deposition tunnels. The device handles backfill blocks made from Friedland clay, stacking them into a backfill array inside the deposition tunnel. Furthermore, the installation device will be used to install Cebogel clay pellets between the backfill array and the walls and ceiling of the deposition tunnel.
Canister inspection device (prototype)
As the copper canister is required to remain intact for tens of thousands of years, its quality must be fully verified prior to disposal. The canister inspection device will be used to check the canister material for any defects. Non-destructive testing (NDT) methods enable quality assurance without changing the characteristics of the actual final disposal product. In addition to ultrasonic and X-ray inspections, the high quality of the disposal canister is ensured by means of eddy current and visual inspection methods.
Tunnel backfilling device (prototype)
The backfill installation device comprises a backfill block stacking system and a pellet installation system. The pellet installation system is used to fill the space between the tunnel wall and the backfill block array with clay pellets. The pellet system and the block stacking system have been developed as separate systems, but are integrated into the tunnel backfilling device. The innovative dust removal function of the pellet installation system guarantees improved operating conditions for the optical equipment required in tunnel backfilling as well as improved working conditions for the personnel. The operation of this function is based on the removal of fine material from the pellet flow at negative pressure. The pellets and the transport air are supplied to the mixing chamber and the fine material is removed as shown in the Figures below.