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Shaft & Silo Nuclear Decommissioning Authority Dounreay Produced by DSRL Community Relations Department - ©2015 The decommissioning of the shaft and silo is one of the largest nuclear clean up job at Dounreay and in Europe. DSRL are required to safely retrieve and restore the waste from the two underground waste facilities, which contain unconditioned intermediate level waste. Key Facts: The shaft was licensed in 1958 as an underground disposal facility for unconditioned intermediate level radioactive waste and was in use up until the 1970's. The vertical shaft is 65 metres deep and 4.6 metres in diameter. A chemical explosion occurred within the shaft on 10th May 1977, which left the shaft's superstructure damaged. The silo, constructed in 1971 is a concrete box set into the 3 ground, with a capacity to store 720m of unconditioned intermediate level waste. The shaft and silo in total contain approximately 1100m³ of intermediate level waste. Between 1970 and 1990, radioactive waste from various site operations was deposited into the silo through ports in the roof on more than 16,000 occasions. The first phase of shaft decommissioning was completed in 2006, when a grout curtain around the shaft was constructed. This significantly reduced water inflow into the shaft. The grout curtain was achieved by drilling 400 boreholes in the rock around the shaft and injecting fine grout to seal up fissures in the rock. The grout curtain is expected to remain for 100 years. The first phase cost in the region of £33 million. The Silo facility The Shaft facility

Shaft & Silo - Dounreay & Silo Nuclear Decommissioning Authority Dounreay Produced by DSRL Community Relations Department ... • The shaft was licensed in 1958 as an underground disposal

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Shaft & Silo NuclearDecommissioningAuthority

Dounreay

Produced by DSRL Community Relations Department - ©2015

The decommissioning of the shaft and silo is one of the largest nuclear clean up job at Dounreay and in Europe. DSRL are required to safely retrieve and restore the waste from the two underground waste facilities, which contain unconditioned intermediate level waste.

Key Facts:

• The shaft was licensed in 1958 as an underground disposal facility for unconditioned intermediate level radioactive waste and was in use up until the 1970's.

The vertical shaft is 65 metres deep and 4.6 metres in diameter.

A chemical explosion occurred within the shaft on 10th May 1977, which left the shaft's superstructure damaged.

The silo, constructed in 1971 is a concrete box set into the 3ground, with a capacity to store 720m of unconditioned

intermediate level waste.

The shaft and silo in total contain approximately 1100m³ of intermediate level waste.

Between 1970 and 1990, radioactive waste from various site operations was deposited into the silo through ports in the roof on more than 16,000 occasions.

The first phase of shaft decommissioning was completed in 2006, when a grout curtain around the shaft was constructed. This significantly reduced water inflow into the shaft.

The grout curtain was achieved by drilling 400 boreholes in the rock around the shaft and injecting fine grout to seal up fissures in the rock. The grout curtain is expected to remain for 100 years.

The first phase cost in the region of £33 million.

The Silo facility

The Shaft facility