A radiation camera developed at U-M may be poised to sweep the field of radiation protection, and its inventor believes it could help to make the areas around Fukushima Daiichi safe once more.
Last December, the young U-M spinoff company H3D, led by Zhong He, professor of Nuclear Engineering and Radiologcal Sciences (NERS), sold its first commercial prototype of their gamma ray imager to the Cook Nuclear Plant near St. Joseph, MI. Since then, it has redefined clean for Robert Hite, the plant’s radiation protection director.
“We’re able to find radioactive materials at levels we couldn’t easily find before,” said Hite. “Literally, we can find radioactive dust with this.”
Hite is careful to point out that the radiation risk that these small contaminations pose is insignificant, many times lower than acceptable dose rates in controlled areas. It’s about preventing a build-up of radioactive material, he explained.
The camera overlays an image of radiation hotspots with an optical image of the room, allowing Hite’s team to quickly identify and clean up any radioactive traces. “All of our technology that we have, that I’ve worked with for 30 years, doesn’t touch what this shows us,” said Hite. “We can find things now in 30 minutes that could take weeks to find.”
Last month, He and Hite both presented at an international conference on radiation safety in Tokyo, Japan. Hite has become accustomed to a degree of skepticism when he shares his experiences using the gamma camera. A real-time radiation imager that operates at room temperature is unheard of in the world of nuclear power plant operation. “It’s so new and so different, people don’t have any idea that this is possible,” he said. “They’re shocked. It leapfrogs our mentality.”
During the conference, He and Hite toured the Fukushima site. An hour-long bus tour took the attendees into the 20-kilometer exclusion zone and the plant grounds. Security remains tight within the Daiichi plant, so Hite left the radiation imager behind along with the cameras and phones of other passengers.
Detectors on the bus measured varying levels of radiation on the journey. Hotspots could deliver the maximum annual dose for US radiation workers in anywhere from a few days, outside the site, to a few hours next to the damaged reactor buildings.
Zhong He noticed that while the tour guide was aware of radiation hotspots, these areas had not yet been cleaned up. “It’s not easy to identify what is emitting radiation because if you send people with current equipment, what they can do is test one by one,” said He. “You don’t want to get close to something like that.”
An imager would allow the workers to pinpoint the radiation quickly from a relatively safe distance, focusing the use of expensive robotic devices or allowing human workers to quickly contain the radiation source and minimize their exposure.
Although the exclusion zone was relaxed last month, allowing residents to visit their former homes and businesses, the radiation levels remain high enough that they aren’t allowed to stay overnight. “It is devastating to see all the houses empty of people,” said He. “The damaged roofs they covered with plastic, just temporary so the rain doesn’t get in.”
Hite believes that the radiation camera would be most useful in places like those, outside the plant grounds but inside that zone, identifying the hotspots for a focused clean-up effort. “They should have numerous cameras,” he said.
Zhong He visited Japanese ministers and nuclear scientists last year with the NERS chair and Chihiro Kikuchi professor Ron Gilgenbach and assistant research scientist Yugo Ashida, demonstrating the camera and offering collaboration, but nothing came of those initial meetings.
After seeing the disaster site and surrounding area in person, He said, “Now I will take a more active attitude trying to share our technology with the Japanese. They tried many cameras, they told me – none of them really worked well. I hope that this time we can give them a different kind of instrument that will work better.”