For the first time since the 9.0-magnitude earthquake on March 11 and the ensuing catastrophic tsunami-crippled reactors at Japan's Fukushima Daiichi nuclear facility, workers entered the damaged building, the country's nuclear safety agency reported.
Days after the devastating tsunami, hydrogen explosions at the six-reactor facility blew off roofs and walls in four of the buildings, spewing radioactive debris.
At 11:30 a.m. Thursday, the first team of workers entered the Unit 1 building to install new air ventilation ducts. Three four-man teams had 10 minutes each to work in a narrow space inside the building, TEPCO spokesman Taisuke Tomikawa told reporters.
Tomikawa said data retrieved from robots that entered the building on Friday showed that radiation levels had fallen sufficiently enough to allow workers in protective gear inside. Officials said it will take four to five days to reduce radiation levels enough to work inside for longer periods of time.
Once radiation levels are sufficiently reduced, workers will be able to install a cooling system that will allow a cold shut down of the damaged reactors.
The government imposed a 12-mile restricted zone around the damaged reactors and evacuated about 80,000 people. Many evacuees are living in temporary shelters in community centers and other facilities.
AP contributed to this report.