Drone-based system developed for aerial radiation measurement in Fukushima

10 May 2019

The Japan Atomic Energy Agency has developed a system employing aerial drones that can measure distribution of radioactive substances across a wide area and generate a 3D display, agency officials said May 9. The JAEA aims to put the system into practical use in fiscal 2019 ending next March.

Conventionally, radiation dosage data is collected on foot or from a car using measuring equipment. But the use of drones facilitates low-cost, prompt identification of situations in areas where it is difficult for residents to return home due to high levels of radiation, or hot spots where radiation dosage is relatively higher than in the wider neighborhood, as a result of the 2011 nuclear accident at Tokyo Electric Power Co.’s Fukushima Daiichi plant.

In difficult-to-return zones, decontamination is under way only in places designated as "specified reconstruction and revitalization bases," while almost no clean-up operations are undertaken elsewhere. The JAEA system is expected to be useful for future decontamination work and many other purposes, including as reference data for the permanent return of residents and for ensuring the safety of clean-up workers.

The development project was also joined by Chiyoda Technol Corp., a Tokyo-based company engaged in the development of dosimeters and other products. Local company Sakae Seisakusho in Minamisoma city also cooperated.

A small, light camera capable of capturing radioactive substances and adding color to the display is mounted on the drone. The camera can show such substances on the ground and in the air as gray-scaled images in color.

A test was conducted last January in a difficult-to-return zone. The system identified the distribution of radioactive substances in an area some 7,000 square meters wide in about 30 minutes. A similar experiment undertaken in the same area using conventional measuring equipment took more than half a day, partly because of vegetation left unkempt in some places, according to officials involved.

Aerial monitoring that surveys radiation dosage with helicopters and other aircraft is in operation, but drones can sharply reduce the cost of measurement compared with aircraft surveys, according to the JAEA.

The drone system "enables us to understand conditions of contamination in wide areas promptly," said Yuki Sato, a researcher at the Collaborative Laboratories for Advanced Decommissioning Science in the JAEA’s Sector of Fukushima Research & Development. "It is also expected to be used for other work, including decommissioning of the Tokyo Electric Power Fukushima Daiichi nuclear plant."

Sato and other JAEA officials spoke about the system at a press conference in the Fukushima prefectural government office in Fukushima city on May 9.

"Technology permitting the geographical identification of radiation dosage at a lower cost is indispensable for the decommissioning work which takes a long time," said an official of the prefectural government’s office promoting the robotics industry. "The system, which has been completed by integrating various technologies, can possibly be employed in other new projects."

(Translated by Kyodo News)