High-resolution radiation mapping to characterise contamination

The Challenge

Radiological contamination exists at numerous sites worldwide; whether the result of large-scale radiological release events (such as the Fukushima Daiichi Nuclear Power Plant accident in March 2011), following nuclear weapons testing, or associated with power generation and the subsequent reprocessing activities.

Alongside many of the sites requiring characterisation being spatially-extensive, topographically challenging and with access restrictions, there exists the need to protect those performing the works from potentially high levels of radiation dose that may exist, distributed across such sites. A platform is therefore needed to undertake such site-wide characterisation.

The Solution

The research and subsequent platform development that has been conducted at the University of Bristol has widespread applications in environmental remediation, but also to the wider nuclear industry as part of regional and side-wide characterisation.

The lightweight (only 500g) and highly portable radiation detection payload; consisting of a miniaturised gamma-ray spectrometer, GPS receiver, distance ranging LiDAR and associated control electronics is more compact and versatile than traditional systems.

While the unit can also be easily carried by an operator on the ground, work at the University of Bristol has seen this detection capability carried by an unmanned aerial vehicle (UAV) for efficient side-wide monitoring. Unlike ground-based surveys (performed by human operatives working in a regularly-spaced grid pattern), the aerial platform presents many distinct advantages.

  • Fully-autonomous.
  • Pre-programmed GPS way-point flying permits survey repeatability
  • Minimal human dose experienced
  • Surveys free from on-ground obstructions
  • Faster ground coverage than ground-based (human) surveys
  • Survey results free from influence of operator shielding
  • Potential fusion with additional sensors and imaging options

The Impact


Above: (left) a 3D photogrammetry representation of one of the waste storage sites that exists around Fukushima Prefecture. (right) a radiation intensity overlay (obtained using the UAV-mounted radiation detection system) applied to this 3D topographic model.

During development and initial testing, the system was successfully deployed on parts of the Sellafield Ltd. nuclear reprocessing site; accurately identifying numerous radioactive “hotspots” as well as identifying the contaminating radionuclides from the on-board gamma-ray spectrometry system.

The radiation mapping system has also been used on numerous occasions on the vast area contaminated by the Fukushima-Daiichi Nuclear Power Plant (FDNPP) accident in Japan to study the evolving nature of the contamination as well as enabling the successful sampling of material for later particle analysis.

Following the time-resolved analysis of one of the thousands of radiologically contaminated waste storage sites using the UAV, species leakage was observed to have occurred. Working with the facilities construction team, a solution to this issue of through-water transport of radionuclides was achieved.

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