A worker dismantling tanks at Japan's wrecked Fukushima No. 1 nuclear power plant was found to have been exposed to a small amount of radiation during a routine safety check on Friday, plant operator Tokyo Electric Power Co. (TEPCO) said.

Radiation was detected in nasal cavities of the worker, an unidentified man in his 30s, a TEPCO spokesman said on Friday. The company estimated the amount of radiation at up to 0.010 millisieverts--less than a typical chest X-ray of 0.05 millisieverts--and said it did not pose an immediate health risk.

Reported radiation exposure incidents have been rare during work to clean up the plant, devastated by the March 11, 2011, magnitude 9 earthquake and tsunami that left nearly 16,000 people confirmed dead, with more than 2,000 officially unaccounted for.

The TEPCO spokesman said the last Fukushima No. 1 radiation exposure incident in official records was for a worker exposed to at least 2 millisieverts in January 2012.