My apologies if this has alrady been posted:

"As far as I can tell from the announcements made by Tokyo Electric Power Co. (TEPCO), the nuclear fuel that has melted down inside reactors at the Fukushima nuclear plant has gone through the bottom of the containers, which are like pressure cookers, and is lying on the concrete foundations, sinking into the ground below. We have to install a barrier deep in the soil and build a subterranean dam as soon as possible to prevent groundwater contaminated with radioactive materials from leaking into the ocean."
In this photo taken on Thursday, March 31, 2011 by Japan Maritime Self-Defense Force and released by Japan Defense Ministry Friday, April 1, JMSDF personnel all in protective suits are aboard a tugboat towing a U.S. military barge carrying pure water towards the quay of the tsunami-stricken Fukushima Dai-ichi nuclear complex in Okumamachi, Fukushima Prefecture, northeastern Japan. (AP Photo/Japan Defense Ministry)
In this photo taken on Thursday, March 31, 2011 by Japan Maritime Self-Defense Force and released by Japan Defense Ministry Friday, April 1, JMSDF personnel all in protective suits are aboard a tugboat towing a U.S. military barge carrying pure water towards the quay of the tsunami-stricken Fukushima Dai-ichi nuclear complex in Okumamachi, Fukushima Prefecture, northeastern Japan. (AP Photo/Japan Defense Ministry)

His comment captured public interest and when I asked a high-ranking government official about it, the official said that construction of an underground dam was indeed being prepared. But when I probed further, I found that the project was in limbo due to opposition from TEPCO.

Sumio Mabuchi, an aide to Prime Minister Naoto Kan who is dealing with nuclear power plant issues, holds the same concerns as those expressed by Koide and has sought an announcement on construction of an underground dam, but TEPCO has resisted such a move.


[link to mdn.mainichi.jp]