A team of Korean scientists say it might be possible to detect radiation up to a kilometer (0.6 miles) away thanks to a novel technique. The research was published in Nature Communications.

Detecting radiation is not easy. At Fukushima, for example, it’s taken years just to locate some of the fuel from the meltdown there in 2011, and the actual clean-up operation is still years away.

The main issue is the range limit of Geiger-Muller counters, used to detect radiation. They measure amongst other things Cobalt-60, which with a half-life of about 2,000 days is a clear indicator of man-made radiation. However, they can only make a reasonable detection at up to 3.5 meters (11.5 feet).

Instead, this team of scientists from the Ulsan National Institute of Science and Technology (UNIST) in Ulsan, South Korea propose using pulsed electromagnetic waves to detect radiation, and say the range can be greatly increased. The idea was first proposed by scientists at the University of Maryland in 2010.

"The proposed technique suggests that detecting the existence of radioactive material at a long distance can be possible," lead author Dr EunMi Choi from UNIST told IFLScience. "[For example], in a high radiation field that human beings and robots cannot access, dirty bomb detection, and any nuclear related activity."

How it works is two-fold. First, a high-powered electromagnetic wave source known as a gyrotron is fired into an antenna, which reflects the waves towards a source. If there is radioactive material present, this creates a plasma that is then broken down by the radiation, producing detectable free electrons, those not attached to an atom.

^{A diagram of how the technique works. Kim et al/Nature Communications}

In their research, the team only performed a demonstration experiment that detected a source about 1.2 meters (4 feet) away. However, they say that it can be scaled up to make a much further detection.

“Owing to the laboratory space and licence, and the electromagnetic power of the source, we were limited to doing the experiment up to a few meters at most,” said Choi. “However, the experiment clearly shows that it is surely possible to extend the detection range to about one kilometer in the same frequency that we used.”

There is clearly still a long way to go with the research. But there are some exciting prospects, particularly for hazardous sites that are difficult for humans or robots to access.

“The authors present an exciting opportunity to remotely detect the presence of radioactive sources,” Dr Ben Britton, Director of MSc in Advanced Nuclear Engineering from Imperial College London, who was not involved in the research, told IFLScience.

“They demonstrate a laboratory device that detects the presence of relatively small amounts of radioactive material (equivalent to approximately 300 grams of highly enriched uranium) by following the breakdown of an electromagnetic field.

“[It] has great potential to assist in detecting the presence of nuclear materials.”