"Radiation expert says outcome of nuke crisis hard to predict, warns of future dangers."
Mainichi Daily News, Sept. 13, 2011.
Hiroaki Koide, radiation metrology and nuclear safety expert at Kyoto University's Research reactor Institute.
"The nuclear disaster os ongoing.   with radioactive materials yet to be contained, we've remained in the unsettling state of not knowing how things are going to turn out. ..... I believe that rthere is a possibility that massive amounts of radioactive materials will be released into the environment again."
"At the No. 1 reactor, there's a chance that melted fuel has burned through the bottom of the pressure vessel, the containment vessel, and the floor of the reactor building, and has sunk into the groung. From there, radioactive materials may be seeping into the ocean and groundwater."
He believes containment water is still leaking underground. He calls for "immediate action must be taken to build underground water barriers that would close off the nuclear power plant to the outside world..... The important thing is to stop any further diffusion of radioactive materials."
He outlines other problems, and ends, "Recovering the melted nuclear fuel is another huge challenge. I can't even imagine how that could be done."
(italics mine).

It is worth going to the Mainichi Daily News website and reading the whole article.
http://mdn.mainichi.jp/perspectives/news/20110909p2a00m0na016000c.html