Photo/IllutrationA ripped plastic wrapping sticks out from a container labeled “1010” in this picture taken on June 6 at the Oarai Research and Development Center in Ibaraki Prefecture after radioactive substances spewed out of the container. (Provided by Japan Atomic Energy Agency)

  • Photo/Illustraion

OARAI, Ibaraki Prefecture--The Japan Atomic Energy Agency on June 15 acknowledged that flaws in its operating procedure for inspecting storing containers led to five workers being exposed to radiation on June 6.

The operating procedure was prepared in May 2017, and it describes the inspection work as a “routine measure.” It never assumed radioactive substances could be spewed into the air because high-pressure gas is “not handled.” No preparations were made for such a scenario.

During the inspection at the agency’s Oarai Research and Development Center in Ibaraki Prefecture on June 6, plastic wrapping inside the container was ripped, and radioactive substances, including plutonium, were released into the room.

The operating procedure says workers should use an unsealed operating space and wear a half face mask covering only the mouth and nose.

The five workers did not deviate from the operating procedure, the agency said.

“The operating procedure itself, which did not assume that the plastic wrapping might be ripped, has problems,” the agency said.

Dosimeters carried by the workers during the accident show they were exposed to 2 to 60 microsieverts of radiation, according to the JAEA. The highest reading is one-800th of the maximum acceptable annual radiation dose for a person.

The accident occurred around 11:15 a.m., when the workers tried to open the container to inspect the storage conditions. The container had not been open since the lid was closed 26 years ago in 1991.

The agency also revealed a picture of the container taken by a worker at 12:55 p.m., based on the camera clock, that day.

The picture shows the ripped plastic and brown discotic objects sticking out of the container.

After taking the picture, one of the workers pushed the objects back into the container and closed the metallic lid.

The contaminated camera has not been taken out of the room, but its data card was recovered on June 14.