Fukushima Daiichi NPS Prompt Report 2013

This is follow-up information of the incident announced earlier today (on June 29) where one in-station service vehicle (a concrete mixer truck) at Fukushima Daiichi Nuclear Power Station went out of the station premises (outside from the main gate) with contamination attached to the upper part of the rear bumper and without having been decontaminated.

We measured atmosphere radiation doses along the travelling route of the vehicle. The measurement resulted in approximately the same levels as these in the Distribution Map of Radiation Dose, etc, provided by the Ministry of Education, Culture, Sports, Science and Technology, whereby it was verified that there are no influences of the travelling of the vehicle.

Further, the contaminated part was such that concrete having a contaminated substance attached was solidly attached to the upper part of the rear bumper. Therefore, we consider the contaminated substance to have been unlikely to fall off easily when the vehicle was travelling.

We also confirmed that the radiation exposure of the driver was 0.012mSv as a result of radiation exposure measurement, which was not a particularly noticeable value.

We are implementing measures for preventing a recurrence of such an incident. The measures include requiring contamination inspectors to more clearly instruct the driver of a contaminated vehicle about the necessity of decontamination through posters, and thoroughly reeducating contract workers who check the completion status of the contamination inspection at the main gate.