The plans will show how radioactive waste is to be retrieved from two underground facilities – a vertical shaft 65 metres deep and a nearby vault set nine metres into the ground – as part of the closure of the Dounreay site.
The water-filled shaft and silo were used in the 20th century for radioactive waste from some of Britain’s earliest experiments with nuclear energy.
Their clean-out is a key part of the site closure contract awarded by the Nuclear Decommissioning Authority to the Babcock Dounreay Partnership earlier this year.
It aims to complete both facilities by 2021, several years earlier than previous forecasts and at less cost to the NDA through innovation in areas such as waste packaging.
An estimated 1500 tonnes of radioactive waste was consigned to the two facilities between 1957 and 1998.
Radiation levels are too high for man-entry to either facility, so robotic equipment will be used to retrieve, analyse, shred and package the waste.
Separate headworks and waste processing facilities will be built above each facility.
A 60-strong team is now working on the project, with employment levels expected to peak at about 200 during the construction phase in 2013-16.
The project team is looking wherever possible to use technology already proven elsewhere such as remote vehicles, cranes, shredders, remotely-operated grabs, water treatment, assay and monitoring.
They will solidify the processed waste in a type of container that is new to Dounreay but proven by the nuclear industry in other parts of the world.
The use of boxes made from steel, lead and concrete will provide shielding from harmful radiation and remove the need to build a heavily-shielded store for the previous design of containers. This will save tens of millions of pounds in design and build costs.
About 20 companies are likely to be involved in contracts ranging from the design and build of mechanical systems such as cranes to the procurement of robotics capable of operating in high radiation zones, major construction, plant decommissioning and back-filling of the shaft and silo.
The project is being managed by Dounreay Site Restoration Ltd, the site licence company acquired earlier this by the Babcock Dounreay Partnership, for the Nuclear Decommissioning Authority.
Project director Bo Wier, who has been seconded from CH2MHILL, one of the parent companies in the partnership, said: “Emptying the shaft and silo at Dounreay is one of the biggest clean-up challenges in Europe and one of the priorities for the Nuclear Decommissioning Authority in the UK.
“We believe we can deliver the decommissioning on an earlier timescale and at lower cost than previously thought by combining proven, off-the-shelf technology with innovation in design.
“By 2021, we aim to have all the waste safely packaged for long-term storage above ground and both facilities left in a condition that do not pose a hazard to future generations. This is significantly earlier than previous estimates and offers substantial cost savings to the NDA.”
Earlier work carried out to decommission both facilities, including hydraulic isolation of the shaft, means construction work can begin quickly once planning permission is obtained.
DSRL is putting the plans on display locally in Reay on Tuesday, September 11, and in Thurso on Thursday, September 13 before making a formal application to Highland Council in October. DSRL is planning to hold an event for the supply chain in the near future to map out procurement opportunities.
Subject to consent, construction work is scheduled to begin in the second half of 2013 and take up to three years complete. Retrieval of waste is expected to take 18 months to complete at the silo and 30 months at the shaft, before both facilities are back-filled with concrete.
[Planning summary document]