A collaboration between two companies has developed a device for detecting radiation-contamination food. After an earthquake and tsunami damaged Japan’s Fukushima nuclear plant in 2011 and caused a significant leak of radioactive material, RIKEN Global Research Cluster and G-Tech began researching methods for detecting radioactive cesium in food.

The detector system on display.
Nearby farmers have struggled with consumer fears about contamination. Current methods of detecting radiation require food to be ground up, so any radioactivity that may be in food on store shelves can’t be measured. The companies are developing the Large Food Non-Destructive Area Sampler (LANFOS) so that food can be tested before consumption. The technology incorporates a silicon photomultiplier, which was developed for space stations. Its low power consumption and low cost are optimal both for outer space and for a food tester designed to be used by non-professionals in homes and schools. One of the challenges of the work was to create a device sensitive enough to distinguish the harmful radiation from background levels of naturally occurring potassium. “This is a problem because official regulations set the maximum level of cesium at near the level of natural potassium 40,” said team leader Marco Casolino of RIKEN. “Fortunately, we were able to develop a mathematical algorithm to separate the two, taking advantage of the initial difference in photon energy, and now we are able to reliably detect the level of cesium in a large container without harming the materials,” he said. A prototype of the device was tested on potatoes, cabbage and Japanese pears at a festival in Minamisoma City, Fukushima, one of the areas contaminated by the accident. “The local people were impressed at the machine’s ability to rapidly give them a read-out of levels of radiation in the food, and this gave them hope that consumers might become more confident about buying their products,” Casolino said. The system will be presented March 24 at the 70th Annual Meeting of the Physical Society of Japan.