Another article from Kyodo News :
" Work to restore power and key cooling functions was disrupted again Wednesday at the crisis-hit Fukushima Daiichi nuclear plant as black smoke caused workers to evacuate, while the fear of radioactive pollution spread to Tokyo with an alert not to give tap water to infants.
Chief Cabinet Secretary Yukio Edano unveiled estimates that people outside of a 30-kilometer radius of the plant, in which residents have been ordered to evacuate or remain indoors, could be exposed to radiation of 100 millisieverts or more, an annual dose believed to be associated with an increased risk of cancer.
Based on the estimates, the top government spokesman urged residents in areas downwind from the power station to stay inside buildings and avoid exposure to air as much as possible as a precaution.
At the disaster-stricken plant operated by Tokyo Electric Power Co., black smoke was seen rising at the east of the No. 3 reactor building, leading 11 workers to evacuate from four of the six reactors and water-spraying operations by fire trucks to be aborted.
The radiation level was unchanged shortly afterward, meaning the smoke did not result in a massive release of radioactive materials, the government's Nuclear and Industrial Safety Agency said. Smoke was also seen billowing from the No. 3 reactor building on Monday but its cause remains unknown."