Japan's nuclear safety officials have reprimanded the operator of the country's crippled Fukushima nuclear and demanded an investigation into how two workers were exposed to radiation more than twice the legally
permitted level of radiation.
The government also ordered the Tokyo Electric Power Company [TEPCO] to reduce workers' risks of heat-related illnesses as concerns grow about the health risks faced by the people toiling to get the the plant under control.
The two men with high radiation exposures worked at a central control room for two reactors when a tsunami struck on March 11 and the days that followed.
They are not showing immediate health problems but will need long-term monitoring for an increased risk of cancer, said the National Institute of Radiological Sciences, which examined the men.
Soon after the tsunami knocked out the plant's power and cooling systems, the government raised the radiation limit for men to 250 millisieverts, from the standard 100 millisieverts, so workers could tackle the emergency.
The results of analyses showed the workers' total doses were above 600 millisieverts.
The two men, one in his 30s and the other in his 40s, were confirmed last week as having exceeded that higher limit and were removed from working at the plant.
A third man, a senior control room operator in his 50s, is being tested further after early findings showed high radiation exposure as well, TEPCO spokesman Junichi Matsumoto said.
The Nuclear and Industrial Safety Agency [NISA] reprimanded TEPCO for violating the limit and ordered the company to submit the cause and prevention measures in a report within a week.
TEPCO has already admitted that workers in the earliest, most chaotic, and most dangerous moments of the crisis did not wear masks, possibly other protective gear as well, and lacked dosimeters to monitor their radiation exposures in real time.
The comoany was previously warned for failing to provide a dosimeter for each worker entering controlled areas of the plant.
Some workers have said full-face masks and protective coveralls in high temperatures make their work extremely strenuous.
"The two men worked under an extremely harsh environment. It is truly regrettable that TEPCO put them to work under such conditions," said Nishiyama.
He said NISA may consider a penalty for the operator, but did not elaborate.
The health and labour ministry has ordered TEPCO to check internal exposures of people who worked closely with the two men and to remove them from plant duties.
About 150 people were control room operators, likely to have been working nearby when the two men were exposed.
'Steps to reduced risks'
Nearly 4,000 people worked at the plant during March, when radiation leaks from the reactors were believed to be at their highest.
With two measuring machines available, about half of that group has been checked so far for their internal radiation levels, which involve exposure from breathing or ingesting radioactive particles. Further examination is pending.
The health ministry have instructed TEPCO to take steps to reduce workers' risk of heat exhaustion and heat stroke.
At least a dozen workers have suffered heat illnesses at the plant, according to NISA and the health ministry, which did not give more details.
Health concerns are also spreading outside the plant. The government says several areas outside the current evacuation zone are showing higher-than-expected cumulative radiation levels.
Recent monitoring also detected strontium, an isotope that accumulate in bones and could increase cancer risks.
The government is still considering whether to evacuate residents of tiny "hot spots" outside the 20km no-go zone.
More than 80,000 people have been forced to leave homes in that area.