Tokyo Electric Power Company says radioactive substances that leaked into the sea at the damaged Fukushima plant over six days from April 1st are estimated at 4,700 terabecquerels. This is 20,000 times more than the annual allowable limit at the complex.
http://www3.nhk.or.jp/daily/english/21_35.html
http://www3.nhk.or.jp/daily/english/21_35.html