Staff likely failed to follow safety regulations at a nuclear research facility in Ibaraki Prefecture where five workers were exposed to radioactive materials in June, a Nuclear Regulation Authority (NRA) inquiry has revealed.
While just after the accident the Japan Atomic Energy Agency (JAEA) stated that there was no way that such a serious incident could have been predicted, the NRA's on-site investigation has revealed that, regardless of whether the accident could have been predicted, the facility staff were working without conducting proper safety procedures.
The accident occurred at the JAEA Oarai Research and Development Center in Oarai, Ibaraki Prefecture, at roughly 11:15 a.m. on June 6, when a worker opened a stainless steel container to inspect the powdered nuclear fuel materials within. The plastic bag inside the container ruptured, exposing the worker and four other staff to plutonium and other radioactive materials. The container had been sealed in 1991, and not opened once since.
"There was no way to know the state of the vessel's contents, so the work was done extremely carefully," the JAEA had initially explained. It had also stated that the workers had been aware that the plastic bag around the materials had degraded over the 26 years it was in storage. The JAEA had also been aware since January of a similar case at another facility where the plastic bag in a container had swelled up.
However, the recent inquiry found that the workers at the Ibaraki facility decided that the item on the inspection safety checklist stating "risk of explosion, rupture or dispersal" was non-applicable before beginning their task, which their supervisor also approved. Furthermore, though there were five sealed workstations in the room, the workers chose to open the container at a simple, unsealed workstation instead. No work plan had been put together prior to the task.
"If the workers had used a sealed workstation, it is clear that this accident could have been prevented," lamented a JAEA representative.
Also, after the accident, it took three hours to set up a temporary decontamination tent for the effected workers. The survey found that the building where the incident occurred was not equipped with the materials necessary to construct the decontamination tent, and no drills for the setup had ever been carried out. In addition, a shower meant to wash away radioactive materials was also found to be broken.
"When handling plutonium, we cannot afford to make inexperienced or groundless decisions," declared NRA Chairman Shunichi Tanaka at a regular meeting of the authority on July 5. "(The JAEA's) safety culture is lacking."