Two men have been hospitalized after they were exposed to radioactive liquid while cleaning a water filtration facility at the wrecked Fukushima nuclear plant, the plant's operator said Thursday.

The incident on Wednesday highlights the dangers Japan still faces in decommissioning the plant that was knocked out by an immense tsunami in 2011 in the world's worst atomic disaster since Chernobyl in 1986.

The two workers, one in his 20s and the other in his 40s, are employees of a partner firm of Tokyo Electric Power Company Holdings and have been admitted to the Fukushima Medical University's hospital to be decontaminated and put under observation, though they did not sustain any visible injuries or complain of ill health.