Work at Unit Two are considered the most pressing as the radioactive water, which was used to urgently cool the reactor and fuel storage facilities when the plant's cooling systems failed after the March earthquake, has been leaking into the turbine building and adjacent facilities.

The water, containing high concentrations of radioactive cesium and iodine, is now being pumped out with an 800-meter hose into a nuclear storage facility. Under the schedule, workers will have to pump up to 10,000 cubic meters of highly contaminated water from the reactor building by April 26.

Japan's Fukushima Daiichi Nuclear Power Plant was seriously damaged by the powerful earthquake and tsunami that hit Japan on March 11. Fukushima's operator has since been struggling to stop radioactive leaks from the plant's crippled reactors.

According to most recent reports, the death toll from the 9.0-magnitude earthquake and tsunami stood at 13,949 as of Tuesday morning, with 13,678 still listed as missing.