Dounreay

Nuclear and Chemical Land Contamination

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

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

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

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

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

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. “

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

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

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

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.