Eight steel sections of the site’s former fuelling machine rings, each weighing between 60-80kg, have been successfully decontaminated, consigned as low level waste (LLW) and stored in a vault. The rings had been originally categorised as ILW.
However, a ‘kernel of an idea’ led to the careful removal and vacuuming of radioactively contaminated walnut shell debris, which was used during the original decommissioning phase in the 1990’s, allowing the rings to be re-categorised as LLW, with the removed walnuts disposed of through an existing waste stream.
Walnut shells are commonly used as a soft abrasive, chosen because they do not damage or scratch surfaces and can remove paint, grease and other debris. This highly successful process means the metal can now be recycled, meaning Magnox don’t have to ‘shell out’ on ILW processing and long-term storage costs at the site – which is operated on behalf of its owner, the UK government’s Nuclear Decommissioning Authority.
Vic Belshaw, Programme Delivery Manager at Trawsfynydd Site, said: “Our initial tests showed the steel was not as radiologically active as first predicted and it was in fact walnut debris inside the rings which was the main source of the higher levels of radiation.
“Removing the debris means we can reduce the amount of waste stored at Trawsfynydd, reducing the long term legacy of the site.”