From the NYT:

Leak Found in Steel Tank for Water at Fukushima

http://www.nytimes.com/2013/06/06/world/asia/tepco-says-water-at-fukushima-is-contaminated.html?src=rechp

This problem seems pretty minor, but it does raise the question: do we really think TEPCO can store hundreds of olympic-swimming pools full of radioactive water for decades w/o any spills into the groundwater?     The fact that they are considering the expense of freezing some of the water indicates that they know that liquid water is hard to contain.