Physicist leads effort to image melted cores



Haruo Miyadera is spearheading a project to use subatomic particles called muons to peer into the damaged reactors at the Fukushima No. 1 power plant.

“Finding out what is happening inside the reactors will be the first step toward dismantling them,” said the 36-year-old physicist at Toshiba Corp.’s Power and Industrial Systems Research and Development Center.

Tokyo Electric Power Co., which runs the power plant, wants to start removing the reactors’ melted fuel cores in 2020. It plans to install muon detection equipment next year that will help them examine the reactors’ interiors, which are too radioactive to probe by direct means.

“I’m excited because our efforts will finally pay off, but also feel terrified when I think about the gravity of our responsibility,” Miyadera said.

Muons are formed when protons from deep space hit Earth’s upper atmosphere. About 10,000 muons shower every square meter of the Earth every minute. Although they penetrate matter readily, they change direction when they pass by uranium, one of the key elements used in making nuclear fuel.

By using muon detectors to trace the muons’ paths before and after they penetrate the reactors, 3-D images showing the position and shape of the damaged fuel rods can be generated.

Miyadera became fascinated by muons while studying particle physics at the University of Tokyo.

“Since there were only a few scientists in the field of muon research, each of us was able to work more effectively,” he said.

After completing the graduate program, he became a research fellow at the University of California. He then got a call from the Los Alamos National Laboratory in New Mexico, which built the world’s first atomic bomb, and was invited to join its muon program to research and develop ways to combat nuclear terrorism.

“Let’s make a better world together,” a Los Alamos official told him. So he entered the laboratory in 2006.

Following the March 2011 disasters, Miyadera suggested that muons might be of great help in examining the insides of the leaking reactors.

Toshiba, a major maker of gadgets and industrial machinery, showed interest in his research and offered him a post at its power research center.

After joining the center in summer 2013, Miyadera succeeded in imaging nuclear fuel in an experiment that made use of a laboratory reactor about 10 percent the size of the wrecked units at the Fukushima plant.

He then continued his research in the United States, thanks to donations from friends and acquaintances, because little money had been allocated to his research, Miyadera said.

Noting that his Los Alamos co-workers also offered him voluntary support after work and even on weekends, he said, “This project is built on the efforts and expectations of many people.”