The Nuclear Decommissioning Authority

 

The pioneering ILW MiniStores project to trial on-site storage of intermediate-level waste (ILW) has been successfully completed at the NDA's Dungeness site and could now support a case for the option to be used elsewhere in the Magnox estate.

Weighing 18 tonnes and holding up to about 2.85m³ of waste each, the MiniStores provide a versatile and cost-effective alternative to the construction of on-site ILW stores across the Magnox sites. One bonus is the potential to save many thousands of pounds that could be used to accelerate other decommissioning work.

The concept has been used extensively in Europe for more than 20 years, where they are used for interim storage, transportation and final disposal.

In the UK, MiniStores have been pioneered at the NDA's Dungeness site, with three boxes recently receiving regulatory approval from the Nuclear Installations Inspectorate (NII) to be used for 13 years storage, though not for final disposal in a repository. However, the project could provide valuable data to support a case for longer-term storage.

 

At Dungeness, the containers hold spent resin from existing storage tanks, freeing valuable space and allowing an additional 10 years' capacity adequate for the projected life of the cooling ponds.

Rigorous testing was carried out during the 20-week pathfinder project before three of the MiniStore containers were filled with active resin slurry, dewatered, sealed and put into storage.

Mike Gull, Project Director, said:

"Dungeness has done a fantastic job, safely delivering the first MiniStores campaign under a huge amount of scrutiny and interest. The site now has first-hand experience that will be invaluable to us."

Magnox North and Magnox South Nuclear Safety Committees have now agreed that the MiniStores can be included in their decommissioning strategies following a detailed analysis of technical issues. This has enabled the Magnox South board to agree a recommendation from the executive to prioritise work necessary to introduce the MiniStore approach into the baseline of lifetime plans.

This will include an opportunity for stakeholders to participate in an optioneering process, forming part of a submission to regulators. Last Autumn, Magnox South stakeholders took part in the first workshop, with more than 60 local community representatives from Magnox North and Magnox South sites now expected to attend a further workshop in September.

Further pathfinder opportunities are now being considered at other Magnox North and Magnox South sites to develop learning and support the ongoing programme of work to evaluate MiniStores as a future strategy.