ZERO HEDGE reports http://www.zerohedge.com/article/tepco-knew-radiation-seawater-75-million-above-normal-it-started-dumping-radioactivity-sea-m
The story can also be found at NHK news http://www3.nhk.or.jp/daily/english/05_27.html
NHK also reports that radioactivity levels cannot be measured at the plant because they are so high and workers cannot enter some reactor buildings:
"Plant radiation monitor says levels immeasurable A radiation monitor at the troubled Fukushima Daiichi nuclear power plant says workers there are exposed to immeasurable levels of radiation.
"The monitor told NHK that no one can enter the plant's No. 1 through 3 reactor buildings because radiation levels are so high that monitoring devices have been rendered useless. He said even levels outside the buildings exceed 100 millisieverts in some places. Pools and streams of water contaminated by high-level radiation are being found throughout the facility..."