completed construction of vaults


Construction of Low-Level Waste Vaults at Dounreay

At the Dounreay site a sustainable solution was required for local disposal of the low-level waste generated from the site’s decommissioning mission. Upon Amentum’s arrival as part of the Dounreay Site Restoration Ltd (DSRL) Parent Body Organisation in 2012 we managed the construction project 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 to manage waste. They have been a cornerstone of the site closure contract.

Historically, the site perceived “decommissioning as king” but as part of the clean-up mission the site needs to demonstrate “optimisation” of waste management. This calls for a significant operational and cultural change. Through implementation of the waste informed decommissioning approach and management of the Dounreay Waste Directorate, Amentum’s senior leaders, as part of DSRL, managed the vault development programme and drove a culture change programme around waste optimisation.

Each vault covers approximately 1.8 hectares and are 11 metres from top to bottom, providing a safe disposal route for 80% of Dounreay’s low level waste. 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, and the drainage and pumping systems ensure that the vaults remain dry during the waste emplacement phase. Since operation of the vaults began in 2014 over 200 half-height ISO containers have been consigned to the vaults for disposal. Once all the vaults are filled, they will be capped, closed and monitored for a period of time. After this period, and time for radioactive decay, there is no requirement for any institutional control as there will be little, or no, hazard associated with the waste and an engineered closure cap will continue to deter any accidental human intrusion into the vaults.

Key Achievements:

  • Ensured environmental compliance and delivered best value for the cost and programme.
  • Implemented new processes to optimise waste management, and stop the production of “orphan wastes,” allowing decommissioning projects to access open and efficient waste routes.
  • Managed backlog of legacy wastes disposed of to the Vaults in line with modern quality requirements.
  • Decreased the amount of rework and “waste rejections” leading to more efficient waste consignment.
  • Reduced the waste volume destined for disposal by implementing the waste hierarchy to use alternative waste routes, presenting environmental benefits and extending the life expectancy of the low-level disposal vaults.
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