11.02.2011 10:19

A new drilling jumbo is here for precision work

A new drilling jumbo, tailored according to Posiva's needs, was received in Olkiluoto at the end of January. The jumbo will be used for excavating the demonstration facilities – a task that requires high precision. For a successful drilling round detonated in the rock, it is very important to drill the holes in the rock as straight as possible and exactly at the intended spots.

Supervisor Kimmo Lehtola, what kind of a drilling jumbo did Posiva receive to the ONKALO site?
Kimmo LehtolaThe drilling jumbo is a Sandvik DT920i. Manufactured in Tampere, Finland. It can be said that it is the best you can get from the store shelf. The drilling jumbo has been equipped according to our needs for optimally accurate drilling. With the jumbo, we will be able to plan round drilling and verify its success. In addition, with the jumbo's software, we can plan the round blasting.

Why did Posiva need a new drilling jumbo?
The previous drilling jumbo would have been too large for excavating the demonstration tunnels. The new one will fit there by a whisker. The jumbo has been equipped for improved drilling precision.

What are the differences between the old and new one?
The new jumbo is smaller. As a result of new software, it is easier to operate the machine. The jumbo is fully computer-controlled. It has tachymeter-based navigation for higher positioning precision. The machine itself also has a scanner for verifying the shape of the excavated space as soon as the machine is driven at the end of the tunnel.
What are the dimensions of the jumbo?
Its length is 15.5 metres, height 3.5 metres and width 2.5 metres. The jumbo weighs 30 tonnes and its radius of turn is 10.7 metres. The machine itself moves by means of a diesel engine, and the drilling is performed electro-hydraulically.

Who will use the jumbo at the ONKALO site?
The goal is that all drillers working at the site will use the new jumbo. Initial training has already been arranged at the factory. Training is needed since the software is of a new kind, and the jumbo's cabin and control devices are different from those of the previous one.

When will the new drilling jumbo be used for excavating ONKALO's demonstration facilities?
According to the existing plans, the excavation of the demonstration tunnels will commence in March. Before the actual demonstration tunnels, we will make a model next to the tunnels. By doing that, we will ensure that we have a well-functioning drilling and blasting pattern for the actual demonstration tunnels. In addition, we will show to the Radiation and Nuclear Safety Authority (STUK) that we are capable of commencing the demanding work. The demonstration tunnels are scheduled for completion in early summer 2011.

What will the demonstration tunnels be like? What is their purpose?
Two demonstration tunnels will be excavated in the facilities. One will be 52 metres long and another over 80 metres long. Test holes for final disposal canisters will be made in both demonstration tunnels. The purpose of excavating the demonstration tunnels is to test the excavation methods of the final disposal facilities and to verify whether the previously collected research data is correct in actual conditions.

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