Japan's Ministry of Health, Labor and Welfare is investigating a report that workers at the nuclear plant in Fukushima were urged to cover up unsafe radiation levels, CNN reported.
Workers for a subcontractor working at the Fukushima Daiichi nuclear plant were allegedly told to use lead covers to hide radiation levels on December 1, nine months after the earthquake and tsunami damaged the plant, CNN said.
A ministry official said, "We'll firmly deal with the matter once the practice is confirmed to constitute a violation of any law."
Agence France Presse said an executive at Build-Up, a construction firm, told around 10 workers to cover their dosimeters – devices used to measure radiation exposure – so the firm could continue to work at the site.
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In a recording the workers had of their meeting with the executive, he said, "Unless we hide it with lead, exposure will max out and we cannot work," according to Japanese daily Asahi Shimbun, said AFP.
According to Japanese public broadcaster NHK, nine workers wore the lead plates over their devices, said Reuters.
Japanese law sets the annual radiation exposure threshold at 50 millisieverts for nuclear plant workers during normal conditions, according to Reuters.
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The Fukushima plant's cooling systems were knocked out during the earthquake and tsunami in March 2011, leading to meltdowns and the release of radioactive material, the BBC reported.
Workers from Build-Up were working in the plant from November to March to restore the facilities, said the BBC.
A spokesman from Tokyo Electric Power, the company that owns the plant, told Reuters that the company was aware that Build-Up made the lead shields, but not that they were ever used.
A Japanese parliamentary panel earlier in July found that the disaster at Fukushima was "profoundly manmade," said the BBC.