Japan probes alleged radiation cover-up

Japanese authorities are investigating subcontractors on suspicion that they forced workers at the tsunami-hit nuclear plant to under-report the amount of radiation they were exposed to so they could stay on the job longer.

Labour officials said an investigation had begun over the weekend following media reports of a cover-up at the Fukushima Dai-ichi plant, which suffered multiple meltdowns following the Mar 2011 earthquake and tsunami disasters.

A subcontractor of plant operator Tokyo Electric Power Co (Tepco) acknowledged having nine workers cover their dosimeters with lead plates late last year so the instrument would indicate a lower level of radiation exposure.

The probe marks the first time the government has examined the case, believed to be part of a widespread practice at the plant.

The government more than doubled the emergency radiation exposure limit soon after the accident, but lowered it back to the previous level in December.

Dosimeter readings determine how much longer a worker can stay on a plant job.

The issue reflects growing concern among the government and Tepco about how to secure a continuous flow of workers to finish cleaning up the plant. Officials say it will take about 40 years to decommission its four wrecked reactors.