Article here:
http://www.yomiuri.co.jp/dy/national/T110327002727.htm
"When three workers were exposed to radiation on the basement floor of the turbine building of the plant's No. 3 reactor on Thursday, the radiation level of the water was 400 millisieverts per hour. The level increased to 750 millisieverts per hour Saturday."
Normal exposure is about 1 sievert
per year. They are getting 0.75 sieverts
per hour. Do the math.