Photo/IllutrationThe fuel research building of the Japan Atomic Energy Agency's Oarai Research and Development Center in Oarai, Ibaraki Prefecture, where the accident occurred June 6. (The Asahi Shimbun)

The Japan Atomic Energy Agency now insists that none of the five workers exposed to radiation in an accident at a research center in Ibaraki Prefecture several days ago has plutonium in their lungs.

The stunning about-face follows a statement June 7 that a worker in his 50s had internal exposure of 22,000 bequerels of plutonium during a medical check after the accident at the JAEA's Oarai Research and Development Center in Oarai.

The JAEA said June 9 the men were examined at the National Institute of Radiological Sciences in Chiba and had received the all-clear.

No plutonium was detected in the other men, either.

The JAEA said it now suspects the initial reading resulted from the fact that plutonium was detected on the man's skin prior to him undergoing proper decontamination.

However, the JAEA, an organization that has been accused of gross bungling in the past, said “it is not going to rule out the possibility of the workers’ internal exposure to plutonium with the results of the recent examination.”

The JAEA said detecting plutonium is extremely difficult and that the NIRS will conduct further and more detailed examinations in coming weeks.

After the accident, a check of the workers’ intake of radioactive substances involved wiping off such substances from their bodies.

The JAEA said radioactive substances were detected in four of the workers during the examination, and that the remaining worker might have also had internal radiation exposure.

The check at the NIRS on June 7 found that radioactive substances were still present on the skin of at least one of the workers.

An additional examination of all five men conducted after cleansing of their bodies turned up no plutonium, the JAEA said.

The incident occurred when the workers tried to open a metallic canister containing plutonium and uranium for the first time in 26 years. The workers were wearing protective clothing and gloves at the time.