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Dounreay

Learn about the extensive Dounreay nuclear site restoration project in Scotland, challenges faced, achievements, and future cleanup plans.

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Dounreay

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Presentation Transcript

  1. Dounreay Nuclear and Chemical Land Contamination

  2. Background • Site on north coast of Scotland set up in 1955 as UK’s centre of fast reactor development • Last reactor ceased operation in 1994 • Fuel reprocessing ended in 1996 • Fuel fabrication ended in 2004 • Construction, demolition and waste management on going • One of the most complex nuclear clean up challenges in the world

  3. Dounreay Site Restoration Ltd • DSRL are the site licence company responsible for the closure programme of the site • Site is owned by the Nuclear Decommissioning Authority (NDA) who contract DRSL to manage the site

  4. Main Environmental Problems • 65m deep shaft containing intermediate level waste is contaminating some groundwater • Fragments of irradiated nuclear fuel were discharged into the sea during reprocessing in 1960s and 70s • 18,000 cubic metres of radiologically contaminated land, and 28,000 cubic metres of chemically contaminated land • Large amount of highly active waste and intermediate level waste in storage • Large amount of uranium and plutonium still on site • Site is threatened by coastal erosion

  5. Shaft • Vertical shaft built in 1950s to construct a low active effluent discharge tunnel • In 1958 authorisation given for the disposal of unconditioned intermediate level radioactive wastes • Hydrogen explosion in the shaft in 1977 caused severe damage to superstructure - material consignments to the shaft ceased • Decision to empty shaft made in 1998

  6. Shaft Clean-up • First phase of decommissioning completed in 2008 – Hydraulic Isolation • Grouting of rock fissures reducing flow of groundwater through shaft • 400 boreholes drilled into rock and fine grout injected under pressure • Water volume reduced from 350m3/day to 12.7m3/day • Water level in shaft maintained below sea level by daily pumping of water • Reduces amount of water that can flow through the shaft and contaminate the rock on the seaward side • After grouting volume of pumped water reduced from 15m3/day to 1.3m3/day

  7. Success of Hydraulic Isolation • Highly Commended at Ground Engineering Awards 2009 • Received Ground Engineering Award and Exceptional Performance Award at the Construction News Specialists Awards 2009 • Received Civil Engineering Award at British Construction Industry Awards 2009 • “an extraordinarily innovative and complex project delivered with extreme care, confidence and total team collaboration. “

  8. Future Shaft Clean-up Plans • Next stage involves removal, treatment and storage of waste • Concept designs for waste retrieval, treatment and storage facilities • In March 2010, DSRL announced a delay to the construction of these facilities • Retrieval of the waste is unique among nuclear decommissioning around the world

  9. End State of Shaft • Initial Options: • Near Field (1m radius): • Natural attenuation; removal of rock; chemical clean; passive out-diffusion; surface seal; local back-flush; local chemical back-flush • Far Field (1-300m radius): • Natural attenuation; removal of rock; flushing with water; flushing with chemicals; in-situ immobilisation • Decision will be assessed by BPEO process

  10. End State of Site • “a restored site, with early release of land once decommissioning was complete “ • Some contaminated ground will be remediated by the end of decommissioning in 2025-32 • Other contamination will be left to decay naturally in the ground through to 2300 • Estimated cost of decommissioning - £2.6bn

  11. Thank you for listening • This case study highlights the need for safe nuclear waste management policies particularly for the new generation of nuclear power stations.

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