4 Janvier 2013
January 4, 2013
Fukushima No. 1 nuclear plant workers who struggled to bring the nuclear crisis under control in its first few months were only checked for radiation exposure to the torso despite the presence of highly radioactive rubble, according to former employees of plant operator Tokyo Electric Power Co. (TEPCO) and other sources.
If nuclear plant radiation doses to the arms, legs and head are higher than to the torso, the law requires plant operators to instruct workers to wear dosimeters on these parts of their bodies in addition to their chests.
TEPCO maintains that it initially measured radiation doses for workers through chest scans. But experts question TEPCO's argument, saying the giant utility should quickly produce estimates of radiation doses to the affected workers' arms and legs.
One TEPCO employee who was in charge of monitoring radiation at the time of the nuclear accident stepped in puddles near the nuclear plant's No. 1 reactor building several times while working to restore electricity to the disaster-stricken station. His shoes and socks were soaked.
Radiation dosages around the area were 10 to 20 millisieverts per hour, but radiation dosages from some rubble under his feet topped 100 millisieverts. Several hundred people were working around the building at the time, the onetime TEPCO employee says.
Workers normally wear ring badge dosimeters on the arms and legs when radiation dosages at hand and under foot are high. But the former employee says he only wore an APD dosimeter in his chest pockets.
''I had numbness in my toes for several months but I did not go to hospital because I thought it was due to the unsanitary environment,'' he recalls.
Another radiation monitoring official says TEPCO did not measure radiation doses to fingertips and the lenses of the eye even when workers disposed of highly radioactive rubble. There are manyfold differences in radiation dosages even between hands and chest. He also says there are cases in which a chest APD for gamma rays cannot properly measure radiation dosages from other forms of radioactive materials that emit a massive amount of dangerous, cell-destroying beta rays.
Ring badge dosimeters were distributed to workers two or three months after the onset of the nuclear crisis, and one of the former TEPCO employees says he and his colleagues were concerned about how much radiation they had in fact been exposed to in the course of their jobs.
A TEPCO spokesman says the Fukushima nuclear plant operator properly monitored radiation dosages with chest APDs because gamma ray levels were initially higher than beta ray levels. As gamma ray levels stabilized due to the introduction of equipment to treat contaminated water, beta ray levels became more apparent, prompting TEPCO to order its employees to wear ring badge dosimeters, he says. Employees had their entire bodies examined for radiation exposure after work and this procedure led to the discovery of three workers who were irradiated with highly contaminated water in March 2011, the spokesman says, adding TEPCO does not see any need for an additional investigation.
But Ikuro Anzai, a professor emeritus of radiation protection at Ritsumeikan University, says workers at the stricken Fukushima plant must have been exposed to fairly heavy beta ray doses from the start of the nuclear disaster. Radiation monitoring can measure contaminants on the body's surface but cannot track radiation dosages to the extremities and head. He says the central government and TEPCO should immediately survey the workers' duties and where they did their jobs to help catch any cancers they may develop early, potentially saving their lives.