James Fisher and Sons : NDL, of which JFN is a consortium partner, wins multi-million pound HALSEF... 15 June 2021

Optimising waste streams throughout the decommissioning process, the strategy promises to minimise required Intermediate Level Waste and associated costs.

Nuclear Decommissioning Ltd (NDL) consortium partners,James Fisher Nuclear (JFN), REACT Engineering, Shepley Engineering and Tetra Tech, will develop an integrated concept and scheme decommissioning plans for the Dounreay Site Restoration Ltd (DSRL) High Active Liquor Storage and Evaporation Facility (HALSEF) at the DSRL site on the coast of North Caithness, Scotland. Key to this approach will be enhanced stakeholder engagement at every stage, with NDL and DSRL working in collaboration to deliver a successful outcome. The decommissioning strategy will adopt a 'Waste Informed Decommissioning' approach to optimise waste streams throughout the decommissioning process, to minimise cost and required Intermediate Level Waste (ILW) storage provisions.

Constructed in 1955 and receiving its first consignments in 1958, the HALSEF facility is one of DSRL's most important decommissioning challenges. The HALSEF store was designed to receive, condition and store medium and high-active raffinates (liquids separated during reprocessing) before being treated and sent to be encased and packaged at the nearby on-site cementation plant.

Bernie Jones, HALSEF project manager for DSRL said:

'The scope of this project is to devise a strategy to decommission basement storage tanks and the freestanding buildings and plant above ground that service them. This will be followed by managing the waste streams so that ILW and the costs associated with its storage are minimised.'

The overarching strategy for the HALSEF plant decommissioning will cover three distinct areas and the differing waste streams they will generate. These are:

• Medium Active Area Decommissioning Plan: Which will look at the plant washings cells, the ammonium diuranate floc and the solvent storage cells.
• Evaporator Decommissioning Plan: To plan the decommissioning and Post-Operational Clean Out of all pipework and equipment of both evaporator plants and the demolition of the reinforced concrete structures themselves.
• The High Active Area Decommissioning Plan: A challenging task to tackle the storage cells and associated furniture, plus two high active cells at ground level. These are all contained within thick, highly shielded, external walls with large, heavy gauge stainless steel tanks and complex pipework throughout.

NDL delivery team lead, Tim Fox, said:

'Vital to the success of this project is to have full stakeholder engagement throughout. Developing the decommissioning plan for the HALSEF facility collaboratively in this way ensures that we develop a successful partnership with the teams at Dounreay, combining our skills, knowledge and experience to deliver an effective solution and real value.'

Decommissioning the HALSEF facility will be a major undertaking that will take DSRL a considerable way along its decommissioning timeline. By delivering a successful strategy in collaboration with the site teams, JFN - with NDL - can play its part in helping DSRL receive global recognition for decommissioning excellence, whilst moving the site towards its ultimate goal of closure.