IAC Team Field Test New Drone Detector System in Cornwall for the First Time

The South West of England has a rich industrial heritage, with hundreds of mines in Cornwall historically operated to extract valuable minerals such as tin and copper. As a major driving force behind the Industrial Revolution, much of the history of what lies underneath the picturesque landscape of Cornwall has unfortunately been forgotten over the past 300 years. Presently, over two decades after the last Cornish mine at South Crofty, the University of Bristol has bolstered its commitment to the preservation of industrial heritage.

Photograph of a landscape taken along the St Just Coastline. In the foreground is untouched green and burgundy bushes. In the middle and background there are remnants of stone buildings, which are Mine Engine Houses. Above the landscape, the sky is overcast.
A photograph of the Rich Industrial Heritage of the St Just Coastline. Pictured are Mine Engine Houses.

Alongside preservation, is the objective to render safe any remaining hazards resulting from legacy mining activities, in the interest of both local communities and the 4 million tourists that visit Cornwall annually. Of particular interest to the University of Bristol Nuclear Industrial Archaeology (NIA) team in the Interface Analysis Centre (IAC) are the naturally occurring radioactive materials such as uranium, thorium and potassium which were unearthed as part of the historic mining activities (most often as an undesirable byproduct in the search for more valuable nonferrous metals). Modern radiation detection technologies developed at the University of Bristol now enable researchers to measure these radiation energy signatures, which are much like unique fingerprints. This tech can be used to localise and identify minerals, ores, specific elements and isotopes and can be deployed at the surface or deep underground. This technology can be used to explore the legacy of the past and to identify strategic mineral resources of the future, such as those needed for nuclear fusion power stations.

In August 2023, IAC researcher Dr Yannick Verbelen and PhD student Ewan Woodbridge deployed to Cornwall to run field trials of novel technologies that have the potential of augmenting the team's technical and scientific capabilities. When surveying areas that are difficult to reach on foot, or those that are potentially hazardous to the team, radiation detection from the air has proven particularly useful. Uncrewed aerial vehicles (UAVs) are able to traverse terrain quickly and can make repeated measurements with consistent accuracy without putting the pilot in direct exposure to the environment of particular interest.

Landscape image of a mine spoil heap. On the far right hand side of the image, on top of what looks like a large, flat topped hill, is the silhouette of a person (PhD student Ewan Woodbridge) looking across the landscape pictured across the rest of the photo. He is flying an Uncrewed Aerial Vehicle with the new radiation mapping payload attached.
PhD Student Ewan Woodbridge flying the UAV with the new radiation mapping payload over a mine spoil heap.

The University of Bristol team has extensive operational experience deploying UAVs for mapping of anthropogenic radiation sources in Fukushima and Chornobyl. The more complex energy spectrum and higher gamma energies of some naturally occurring radioactive materials, however, requires specialised hardware and software to more accurately identify them. In a close partnership with ImiTec Ltd, a University spin out company specialised in airborne radiation detection technology, the Bristol team deployed a first of its kind low altitude UAV specifically equipped for the detection and analysis of gamma radiation emitted by naturally radioactive minerals. The technology consisted of a larger volume CsI(Tl) gamma-ray spectrometer that demonstrated a 10 fold increase in the sensitive volume compared to previous sensor payloads deployed by the team in Chornobyl and Fukushima.

After numerous trial flights at the University of Bristol Fenswood Farm Facility, the rough terrain along the St Just headland of Cornwall, dotted with remnants of copper, tin and arsenic mining was found to be an ideal location to field test the UAV with radiation detection equipment in an environment representative of many situations encountered in the field. Deployed on the DJI M600 UAV supplied by the National Nuclear User Facility for Hot Robotics (NNUF-HR), the modified ImiTec AARM radiation detector was used to search for radiation anomalies which are known to exist in the area as a result of uranium-containing minerals present in low concentrations in mine dumps and tailings. The field trials confirmed previous simulations made by the team, proving the sensitivity of this new CsI(Tl) detector for naturally occurring radioactive materials (NORM), as evidenced by the substantially improved signal-to-noise-ratio (SNR) of the recorded photopeaks. The positive results obtained for NORM have wide scale and economically significant implications, since it may enable researchers to find and track occurrences of precious minerals that are coincident with NORM such as deposits of copper, tungsten and even gold.

Photograph of a drone, aka an uncrewed aerial vehicle, above the Cornish coastline. The background is the ocean. Photograph of a drone, aka an uncrewed aerial vehicle, above the Cornish coastline. The drone is above some large rocks. The background is the ocean.

 

 

 

The DJI M600 mounted with the modified ImiTec Ltd AARM containing the larger volume CsI(Tl) detector flying over a spoil heap that have been left behind after the closures of the mines along the St Just headland.

IAC researchers are hoping also to verify that such radiation mapping can be used to identify hard-rock lithium deposits during their next Cornwall field deployment. If found to be a reliable technique with demonstrated statistically significant correlations in data sets, the novel radiation sensing technology will likely find additional applications in other academic and industrial fields such as agriculture for the investigation of crop and soil health, and even as a method to locating water sources.

Words kindly written by Ewan Woodbridge

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