The Nuclear Decommissioning Authority

Estimated savingsof £46 million are set to be secured through a new approach to assessing volumes of low level waste (LLW) on Magnox sites.

The 'Smart' inventory process, developed by Magnox Ltd, is now being shared with other NDA sites in a programme of joint working, and is leading to a more detailed understanding of the nature of the waste, as well as quantities in the NDA estate and possibly wider.

Millions of tonnes of LLW are predicted to arise at old nuclear facilities over the coming decades as equipment is removed and buildings are demolished – an inevitable consequence of environmental restoration.

Some of the resulting soil, building rubble and scrap metal could however, be re-used, recycled or disposed via alternative routes while large quantitie sare also destined for the UK's Low Level Waste Repository (LLWR) near Drigg in Cumbria. Understanding waste quantitiesand characteristics more accurately arecrucial to finding more sustainable waysto dispose of the material and make useof new treatment and disposal routeswhich were not previously available.

The SMART inventory process involves re-estimating anticipated volumes using a combination of techniques including a visual walk-down of all active areas of plant with reactor staff, plus remote assessment of inaccessible areas. The operating experience of reactor staff has been particularly valuable in identifying contaminated plant and areas of potential contamination which could be decontaminated based upon past experience.

Across the 10 sites operated by Magnox Ltd, the review has led to a significant improvement in the understanding of LLW volumes at sites and will potentially reduce the number of waste containers destined for the LLWR by more than 9,000, the equivalent of two national disposal vaults which cost approximately £20 million each.

Based on the work, earlier this year, Magnox, LLWR and Sellafield took part in the first joint project of its kind, involving a week-long waste inventory assessment of the Calder Hall site at Sellafield in Cumbria.

The main aim was to re-assessand challenge the current waste inventory projections for Calder Hall site and underpin the numbers using available documentation, key learning from existing Magnox sites such as Chapelcross, which shares many similar design features, and any other feedback from the site reviews. The process reduced the projected number of waste containers by almost 50%, from 1,100to 578.

The work, expected to be the first of many reviews across both the NDA and non-NDA estate, is aligned to the collaborative drive to improve the understanding of LLW through the implementation of the UK Strategy for the Management of Solid Low Level Radioactive Waste from the Nuclear Industry.