The operator of a nuclear research facility north of Tokyo says the 5 workers who were accidentally exposed to radioactive substances had spent 3 hours in the contaminated room.
The workers were inspecting fuel storage containers at the facility of the Japan Atomic Energy Agency in Ibaraki Prefecture on Tuesday when the incident occurred.
Four of them suffered internal radiation exposure when a bag of powdered radioactive substances, including plutonium, ripped and the contents spilled out. One of the 4 was found to have 22,000 becquerels of plutonium 239 in his lungs.
The agency officials said on Friday that a tent was set up outside the room after the accident to prevent radiation from spreading.
They said the workers remained in the room for about 3 hours until the tent was ready.
The officials said they swiftly began preparations to evacuate the workers after instructing them to stay as far away as possible from the ripped bag.
The agency plans to investigate whether the evacuation procedures affected radiation exposure.
Jun. 9, 2017 - Updated 07:07