Radiological Protection in an Explosive Atmosphere: Dealing with legacy waste packages in the Sellafield Analytical labs
Izzy Styles is a Radiation Protection Advisor at Sellafield Ltd, with 18 years of nuclear industry experience, primarily in operational radiological protection for high hazard facilities.
At Sellafield ' s Analytical Services facility, a legacy waste issue quietly evolved into one of the most serious hazards the site had faced in recent years. The facility, originally constructed in the 1950s, has long been a centre for routine and ad-hoc sample analysis. But decades of wet analytical methods had left behind thousands of bottles of liquid radioactive waste, containing alpha-emitting materials such as plutonium nitrate.
While the majority of these bottles were eventually retrieved and disposed of, a small number( 35 in total) remained sealed inside a glovebox. These bottles, made of highdensity polyethylene( HDPE), had been double-wrapped in PVC and left undisturbed for years. Over time, the radiolytic breakdown of the liquid contents produced hydrogen gas, which became trapped inside the PVC layers. The result was a series of inflated, tightly packed packages with visibly degraded containers and a growing risk of hydrogen deflagration.
Hydrogen deflagration is a subsonic explosion that occurs when hydrogen gas mixes with air and ignites. In this case, the concern was not just the ignition of a single package, but the potential for a chain reaction. The packages were stored in close proximity, and a deflagration in one could easily ignite the PVC of adjacent packages, leading to a“ domino effect” that could result in structural damage and significant radiological consequences.
Safety case assessments outlined the severity of the risk. Under reasonably foreseeable fault scenarios, operator doses could exceed 20 mSv, with the potential for serious harm if multiple packages ignited. Although the likelihood of spontaneous ignition was low while the glovebox remained undisturbed, the degradation of the packages meant that time was a critical factor and recovery was essential.
To address the explosion hazard, a Dangerous Substances and Explosive Atmospheres Regulations( DSEAR) assessment was carried out. The recommended mitigation was to inert the glovebox with argon gas, removing the oxygen required for combustion. This approach significantly reduced the risk of explosion but introduced a new challenge: the prohibition of electronic devices in proximity to the glovebox. This included mobile phones, digital watches and crucially, electronic personal dosimeters( EPDs) and health physics instruments.
The Dangerous Substances and Explosive Atmospheres Regulations 2002( DSEAR) require employers to control the risks to safety from fire, explosions and substances corrosive to metals.
The absence of EPDs raised concerns among operators. These devices are a familiar part of routine radiological protection, offering real-time dose monitoring and reassurance. Without them, operators felt exposed to potential risks. The situation led to a series of tense meetings involving operators, safety representatives and management.
To address these concerns, a comprehensive radiological protection strategy was developed. Sellafield ' s statutory dosimetry relies on whole body thermoluminescent dosemeters( TLDs), and historical health
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