Hisashi Okazaki is seen doing diving work at the Fukushima Daiichi Nuclear Power Plant’s No. 3 reactor in May 2006, in this image provided by Okazaki.

October 11, 2020

Have you ever heard of atomic divers? Hisashi Okazaki, 58, who has worked at nuclear power plants as a diver while being exposed to radiation, wants people to know that professional divers like himself work in dangerous conditions for nuclear reactors to run, as the 10-year anniversary of the Fukushima nuclear disaster approaches.

Among the places he has worked in his 33-year career as a professional diver is the Fukushima Daiichi Nuclear Power Plant, which would later go on to enter a meltdown following the Great East Japan Earthquake and resultant tsunami in March 2011.

Hisashi Okazaki is seen in Ehime Prefecture on Sept. 18, 2020.

After graduating high school, Okazaki, a resident of Seiyo in the western Japan prefecture of Ehime, entered the Japan Ground Self-Defense Force. Four years later he left, and got his professional diving license. Since then, he has worked primarily as a self-employed diver taking on jobs both at home and abroad, fulfilling tasks including laying oil pipelines and tetrapod sea defenses, as well as fixing sea walls damaged after the 1995 Great Hanshin Earthquake. He keeps illustrations of his dives as a record of what he’s done, and in all he has amassed more than 3,670 so far.

In 2006, a diver Okazaki knew invited him to work nuclear jobs. It was his first time working inside nuclear power facilities and being exposed to radiation, but he agreed to do it. Looking back, he said he did it because “I thought I wanted to experience anything I could. I had no fears.” His daily pay was 47,000 yen, almost twice the regular pay of around 25,000 yen for a day’s normal diving work.

Ahead of the job, 20 divers came together to train at a facility belonging to a heavy machinery maker situated in Kanagawa Prefecture south of Tokyo. They had on special heavy helmets weighing around 15 kilograms, and wore dry suits altered to stop water from entering them. They were hooked up to six cables, including for an air hose, photography, and radiation measurements. Both of their arms and legs as well as their chests were fitted with dosimeter equipment. After a week of training, the divers were dispersed to a number of nuclear plants across the country. Okazaki was dispatched to the Fukushima Daiichi Nuclear Power Plant’s No. 3 reactor.

There, he dived into the plant’s suppression chamber, which cools the reactor containment vessel in the event that the release of steam causes its pressure to rise. The chamber is a doughnut-shaped facility in the lower part of the vessel, with water about 3 meters deep in it. The maintenance work Okazaki undertook had to be done while it was filled and he did the work with another diver to exchange equipment in the facility.

An illustration of a diver replacing equipment underwater is seen in this image provided by Hisashi Okazaki.

The area where they worked had high doses of radiation, and in a single day’s diving they could work for about two hours. When they approached an area with a particularly high dosage, they would be instructed via a voice cable not to proceed further. The divers stayed in Fukushima Prefecture for about a month. Legal occupational exposure limits to radiation for a worker are set at 50 millisieverts per year, but in just the 12 days Okazaki worked at the plant, he was exposed to a total of 7.34 millisieverts. At the end of the job, the contaminated equipment they’d used was all put into a drum and disposed of.

“I couldn’t feel satisfied doing a job that leaves no trace of it behind,” Okazaki said. On his way back from Fukushima to Tokyo, Okazaki asked himself while in a car the purpose of his work that exposed him to radiation, and the younger diver who worked with him on the job said, “We did this for that view (of the city) at night, didn’t we?” Okazaki felt a little bit relieved by what they’d said, and after that he went on to do underwater cleaning work at the Onagawa Nuclear Power Station in northeast Japan’s Miyagi Prefecture.

Then, in March 2011, the Great East Japan Earthquake struck. Okazaki watched images of the hydrogen explosion at the Fukushima Daiichi Nuclear Power Station’s No. 3 reactor from a TV on a work barge in the sea off the Muroto Misaki cape in Kochi Prefecture, western Japan. “I’d never imagined the power would be lost and it would explode,” he said.

The use of divers for the decommissioning of the crippled nuclear reactor, such as in removal work and other tasks, is being considered. Even now, around 4,000 people are working at the Fukushima Daiichi plant each day. The decommissioning work, which is expected to take decades from now to finish, is employing robots to complete some tasks, but still the role of radiation-exposed human workers is vital. Okazaki said, “Even at the reactors that use the most technologically advanced equipment, there are sections which only human hands can deal with, and divers are part of the group of workers who take up such jobs.”

(Japanese original by Shunsuke Sekiya, City News Department)

https://mainichi.jp/english/articles/20201009/p2a/00m/0na/020000c