Beat of the drone - measuring radiation at disaster sites

Materials World magazine
,
1 Feb 2014

In the event of a nuclear disaster, ascertaining the extent of the problem is usually the first task. But in instances such as the 2011 Fukushima Daiichi nuclear incident, it is difficult to know the extent of the danger until workers are already too close to the source of radiation.

Sikorsky UK-60 Black Hawk helicopters are usually deployed in such situations, but cost around £10m each and once exposed to dangerous levels of contamination, this kit would need to be contained and possibly even disposed of.

Specialists working in the aftermath of the Töhoko earthquake and subsequent tsunami were exposed to significant levels of radiation, as there was no alternative testing method available. A semi-autonomous drone could be a solution to this problem. Jointly funded by the EPSRC and Sellafield, both in the UK, a team of researchers at the University of Bristol, UK, has unveiled the ARM system.

Dr Tom Scott, Director of the Bristol Interface Analysis Centre, who led the project, explains the materials science behind the drone. ‘The device’s frame is made from carbon fibre. The lighter you can make the frame, the longer you can stay in the air,’ he says. Weighing just 5kg and powered by six motors that run on lithium-ion polymer batteries, the system can remain in the air for around one hour, giving time to cover a disaster area and conduct tests.

Scott explains that in creating the device, the team had stumbled across problems with radiation detectors. ‘Semiconductor-based models stop working at certain levels of radiation,’ he says. Adding insulation to protect the device’s delicate electronics from radiation damage would create too much extra weight, so instead, the team made use of a diamond-based system originally developed at the University, which can withstand extremely high levels of radiation. The device also uses a cadmium zinc telluride gamma spectrometer, thermal sensors and video-imaging to map radiation remotely.

‘In a disaster scenario, this system could be deployed at the touch of a button,’ Scott says, adding that this would not only save time and money but potentially lives, too. Costing 100 times less than the manual tests currently used, and easily destroyed in the event of contamination, the device offers significant advantages over existing test methods.

Dr James Macfarlane, who co-invented the device, adds, ‘There are many advantages to mapping remotely, not least in that it de-risks the activity in that the operator does not have to be within the active region. It also allows for data to be collected from areas that would not be able to be monitored otherwise.’ A prototype is undergoing final beta testing and the team aims to have the drone ready for use in six months.