Concrete from decommissioned nuclear sites should be reused to fill in voids after reactors are demolished, an Aecom-led report concludes.

The Nuclear Decommissioning Authority (NDA) tasked Aecom with the research, which was included in the NDA’s Direct Research Portfolio Annual Report for 2018-19.

The NDA is responsible for cleaning up the legacy from the UK’s post-war nuclear programme. Since merging with Research Sites Restoration Limited, its Magnox Limited business is responsible for decommissioning 12 nuclear sites and one hydroelectric power station.

These include Berkeley, Bradwell, Calder Hall (located on Sellafield site), Chapelcross, Dungeness A, Harwell, Hinkley Point A, Hunterston A, Oldbury, Sizewell A, Trawsfynydd, Winfrith and Wylfa.

It is estimated that the Magnox reactor sites will generate 1.3M.t of concrete during demolition. Removing this for disposal at landfill sites would require 140,000 truck movements, at an estimated cost of almost £150M.

Instead, Aecom’s report suggest concrete reuse on site would minimise the need to transport rubble elsewhere for disposal and to bring in other materials for void infill or landscaping. This would save time and costs, and minimise environmental damage.

Some concrete rubble will be radioactive and therefore would not be able to be reused, however Aecom concludes that the majority will be conventional demolition material that could be reused.

Recycled concrete-based materials (RCM) also generate highly alkaline and metal leachate when exposed to water. Leachate can enter groundwater, drainage systems or surface water, altering the surrounding ground characteristics and affecting vegetation and wildlife.

This could undermine the environmental and cost savings and breach regulatory guidelines.

Having said this, RCM is classified as inert under EU waste legislation, which implies minimal environmental consequences. Different leachate characteristics also result from the varied range of concrete compositions, coarseness of the rubble, level of compaction, duration of exposure to air/water and surrounding rock/soil types.

Reuse of RCM is common in the construction and demolition industries. However, it tends to occur immediately after it has been generated and is used to infill very shallow voids such as roads.

In this case, however, the demolition of cleaned-up nuclear facilities with deep foundations (for example, turbine halls or reactor buildings) will create large voids, and stockpiles of RCM may also be stored for decades before reuse is required.

A series of recommendations will now be developed for planning demolition projects.

By Catherine Kennedy