Six more employees of Tokyo Electric Power Co. working at the Fukushima No. 1 nuclear power plant were exposed to more radiation than allowed even under the relaxed limits put in place to deal with the critical accident.
Six more employees of Tokyo Electric Power Co. working at the Fukushima No. 1 nuclear power plant were exposed to more radiation than allowed even under the relaxed limits put in place to deal with the critical accident.
In addition, 102 workers have been exposed to more radiation than allowed for nuclear power plant workers. Such workers are subsequently prohibited from working at nuclear power plants for up to five years under normal circumstances.
If more workers are discovered to have exceeded radiation exposure levels, TEPCO may face a serious shortage of workers even while the situation at the Fukushima plant is far from under control.
The government raised the upper limit for workers dealing with the Fukushima accident to 250 millisieverts. However, TEPCO announced June 13 that six additional employees had been exposed to more than that level of radiation. The company had previously announced that two employees had been exposed to more than 250 millisieverts.
What makes the situation serious for those six is that all have been exposed to more than 250 millisieverts through internal contamination by which they have inhaled the radiation.
The normal upper limit for workers at nuclear power plants is 100 millisieverts. TEPCO announced that a total of 102 employees had been exposed to more than that level.
TEPCO submitted a report to the Ministry of Health, Labor and Welfare on June 13 of a study into the 3,726 workers at the Fukushima No. 1 plant who worked between March 11, when the Great East Japan Earthquake struck, until March 31.
Of those workers, radiation exposure levels for 2,367 workers who were tested were reported to the labor ministry. The results of the study for the remaining workers will be submitted by June 20.
The eight workers found to have been exposed to more than 250 millisieverts were all male TEPCO employees.
The six employees who were added to the list in the latest report worked to restore equipment at the Fukushima plant as well as measure radiation levels.
The worker found to have the highest radiation exposure level was found to have been exposed to 497.6 millisieverts.
The labor ministry instructed TEPCO to remove a total of 12 workers exposed to more than 200 millisieverts from all emergency work at the Fukushima plant.
Of workers who were not exposed to more than 250 millisieverts, 23 were exposed to more than 100 millisieverts through internal contamination alone. A total of 94 workers were exposed to more than 100 millisieverts when internal and external contamination levels were combined.
Including the workers covered in the latest study, a total of about 7,800 individuals have been working at the Fukushima No. 1 plant through late May to restore operations.
The labor ministry has asked TEPCO to submit a report on total radiation exposure levels, including internal contamination, for all those workers by the end of June.
However, a problem for TEPCO is that the March 11 quake and tsunami devastated the systems to measure external and internal contamination levels.
Dosimeters at the Fukushima plant were damaged by the disasters so TEPCO had to borrow dosimeters from other nuclear plants. While that was completed in April, the company still has not installed enough equipment to test for internal contamination.
The local labor bureau has instructed TEPCO to improve its practices, and the Nuclear and Industrial Safety Agency has also issued a warning.
TEPCO officials and workers admit that internal contamination may have spread because all workers were not given clear instructions to wear face masks when working at the plant.
Another problem is that the emergency work station on the grounds of the Fukushima plant was damaged by hydrogen explosions at two reactors. That created cracks that allowed radioactive materials to leak into the work station, even though it is designed to prevent such leakage.
Because workers believed that radiation would not leak into the work station, they removed face masks when in the station, leading to the internal contamination.
Moreover, the whole body counters at the Fukushima plant used to measure internal contamination were exposed to radiation during the nuclear accident so there was no way of differentiating if measurements reflected contamination of workers or contamination of the equipment.
Workers had to be measured for internal contamination using two whole body counters at a facility in Iwaki, Fukushima Prefecture, away from the nuclear plant.
Labor ministry officials are caught in a bind because even with the relaxed upper limit for radiation exposure at the Fukushima No. 1 plant there could emerge a situation in which TEPCO does not have enough workers.
The labor ministry may be asked to further relax the radiation exposure levels if the work at the Fukushima plant becomes prolonged.
The labor ministry has also asked the Ministry of Economy, Trade and Industry, which oversees TEPCO, to compile a new structure to foster individuals capable of working at nuclear plants.