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Construction work starts on underground characterisation facility at Olkiluoto

Research into the final disposal of spent nuclear fuel entered a new phase today when Posiva Oy, which is responsible for the project, started construction work on the ONKALO underground characterisation facility at Olkiluoto. The over 500-metre deep tunnel leading down to the characterisation facility is expected to be completed by 2010. Sinikka Mönkäre, Finnish Minister of Social Affairs and Health, set off the first blast that signified the start of the construction of ONKALO.

The spiral access tunnel leading down to ONKALO is being excavated in three shifts, five days a week using the drilling and blasting method. Construction work will employ 40-50 people each year.

“ONKALO is an exceptional rock construction project. Since we will utilise ONKALO to excavate the final repository, we have to take long-term final disposal safety criteria into account already at this stage,” says Posiva Oy’s managing director Veijo Ryhänen.

”Whilst excavation in itself is no different from conventional rock construction, we have to pay particular attention to sealing the rock surrounding the tunnel. Alongside excavation, we will bore into the rock and chart the facilities excavated. Additionally, we will carry out geophysical and chemical surveys in the research cavities excavated in the tunnel,” says ONKALO project manager Tapani Lyytinen.

Research conducted at ONKALO will provide information to define the characteristics of sections of rock identified as being suitable for final disposal. Information is required when Posiva submits an application to build the final disposal facility to the Finnish government by the end of 2012. It is planned to commence the final disposal of spent nuclear fuel at Olkiluoto in 2020.

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