completed construction of vaults


Construction of Low-Level Waste Vaults at Dounreay

As part of the Parent Body Organisation (PBO) at Dounreay Site Restauration Ltd (DSRL) Amentum was responsible for management of the construction of the unique near surface disposal vaults adjacent to the site. The two vaults, at a capital construction value of £30m, were the first to be commissioned in Scotland to manage low level waste (LLW) arising from site decommissioning activities and providing a safe disposal route for 80% of Dounreay’s LLW. They are a cornerstone of the site closure contract.

Each vault covers approximately 1.8 hectares and is 11 metres from top to bottom. The largest vault is 80×50 metres, the second vault only slightly smaller. Each vault consists of a reinforced concrete floor slab founded on bedrock with reinforced concrete walls and sheltered by a portal frame cover building. The drainage and pumping systems ensure that the vaults remain dry during the waste emplacement phase. Operation of the vaults began in 2014 and over 200 half-height ISO containers have been disposed. When the vaults are filled, they will be capped and closely monitored for a period of time allowing for radioactive decay. After this period there is no requirement for institutional control as there will be little, or no, hazard remaining, and the engineered closure cap is designed to deter any accidental human intrusion into the vaults.

Key Achievements:

  • Constructed 2 near surface LLW disposal Vaults
  • Secured associated licencing and commissioning
  • Provided a local disposal solution for LLW generated from decommissioning activities at the Dounreay site
  • Enabled the implementation of Dounreay site’s LLW Strategy.
  • Ensured environmental compliance and delivered best value for the budget and programme
  • Implemented new processes to optimize waste management and stop the production of ‘orphan waste streams’ allowing decommissioning projects to access open and efficient waste routes
  • Managed a backlog of legacy wastes disposed to the vaults in line with modern quality requirements
  • Decreased the amount of rework and ‘waste rejections’ leading to more efficient waste consignments.
  • Reduced the waste volume destined for disposal by implementing the Waste Management Hierarchy and utilization of alternative waste routes
  • Presented environmental benefits and extended the life expectancy of the LLW disposal vaults
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