Dounreay is now Europe's biggest nuclear site closure project – and the decommissioning of the shaft and silo, which contain unknown and untreated intermediate-level nuclear waste, is one of the largest nuclear clean-up jobs in Europe. We’re responsible for returning the site to its original, 100% uncontaminated state.

That means, amongst many other things, safely retrieving waste from these two underground facilities. In total, the shaft and the silo contain around 1100m3 of waste. The shaft was in use up until the 1970s when it was damaged by a chemical explosion. Meanwhile, the silo is a concrete box set into the ground that was built in 1971.

Before we even started, our team of Process Engineers, including graduate Mohammed Abdallah [link to profile], used state of the art 3D modelling software to visualise every stage of this delicate process – so that any problems or issues could be thoroughly ironed out at testing stage before any actual work begins. 

It’s a hugely complex challenge: the stored waste is in a variety of sizes, shapes and forms – from big, solid objects to radioactive sludge and water. The waste needs to be carefully removed from each site using specially designed cranes and grabbers. Then it will be sorted, cut down in size where possible and treated or conditioned to remove any radioactivity risk. We’re aiming to have the entire site back to normal by 2025.

The most important thing for me has been increasing confidence in my engineering judgement. Your studies can’t really prepare you for this – it’s about making secure and logical engineering judgements.

Mohammed Abdallah, Process Engineer