26 Octobre 2015
October 26, 2015
THE ASAHI SHIMBUN
Thirty-eight percent of emergency personnel who worked in the immediate aftermath of the Fukushima nuclear disaster received radiation doses exceeding the 1-millisievert annual safety level for ordinary people, a survey showed.
But none of 167 police officers and firefighters or the 2,800 members of the Self-Defense Forces surveyed received a dose of 100 millisieverts, the acceptable limit for nuclear plant employees and emergency workers.
In fact, the highest dose found in the survey was 10.8 millisieverts for an SDF serviceman, according to the Cabinet Office’s survey released on Oct. 26.
The survey is the first to disclose the actual values of radiation exposure among those who worked outside the Fukushima No. 1 nuclear power plant after the Great East Japan Earthquake and tsunami struck the plant on March 11, 2011, a Cabinet Office official said.
The surveyed workers were engaged in evacuation, rescue and cargo transfer operations within 20 kilometers of the nuclear plant between March 12 and 31 that year.
According to the findings, 62 percent of the surveyed workers were exposed to less than 1 millisievert of radiation during the period.
Nineteen percent received a radiation dose of between 1 millisievert and 2 millisieverts, and 5 percent were exposed to 5 millisieverts or higher.
Those exposed to at least 5 millisieverts were all SDF personnel, whose work included dismantling off-site structures and setting up camp for other activities.
The Fukushima prefectural government has estimated the average radiation exposure level for local residents at 0.8 millisievert and a maximum dose of 25 millisieverts.
Employees of Tokyo Electric Power Co., operator of the nuclear plant, received an average dose of 21.57 millisieverts in March 2011, with one worker exposed to a maximum 670.36 millisieverts in the month.
Firefighters who dumped water on the site to cool the damaged reactors were exposed to up to 29.8 millisieverts of radiation, according to the measurements.
Nearly 40 percent of roughly 3,000 police officers, firefighters and members of the Self-Defense Forces (SDF) who helped rescue residents near the Fukushima No. 1 Nuclear Power Plant after the outbreak of the nuclear disaster in March 2011 were exposed to at least as much radiation in about 20 days as the yearly limit for ordinary citizens (1 millisievert), a government survey has found.
The cumulative limit for police officers, firefighters and SDF members working during an emergency is 100 millisieverts, and external radiation exposure of all workers fell under this level. The same upper exposure limit as ordinary citizens is applied to bus drivers and local government workers who joined police officers at the scene to guide evacuees, however -- and the latest survey results may influence future measures to protect workers.
While radiation exposure levels among people working on the grounds of the Fukushima No. 1 plant operated by Tokyo Electric Power Co. have been released in the past, the latest survey results mark the first time that radiation doses for those working around the plant have come to light.
The government decided to hold a working group meeting on Oct. 26 to consider how to lower radiation exposure among local government employees in the future by using the results of its survey.
The survey covered about 2,800 members of the Self-Defense Forces who worked within a 20-kilometer radius of the Fukushima No. 1 plant between March 12, 2011 -- the day after the outbreak of the disaster -- and March 31 of that year, along with roughly 170 police officers and firefighters. Their tasks included guiding evacuees, performing search and rescue operations, and transporting injured people. Since all of them were wearing full-body radiation suits and masks, their internal radiation exposure was presumed to be zero in the survey. Data was collected from individual dosimeters measuring external exposure.
The survey found that 62 percent of Self-Defense Force members received a dose of less than 1 millisievert of radiation, while the remaining 38 percent registered levels upwards of 1 millisievert. The highest figure was 10.8 millisieverts.
Among police officers and firefighters, 12 percent were exposed to a dose of 1 millisievert or more, while the maximum dose was 2.2 millisieverts. Overall, 36 percent received a dose of 1 millisievert or more.