http://www.asahi.com/english/TKY201104250125.htmlKeiji Miyazaki, professor emeritus of nuclear reactor engineering at Osaka University, said that filling the containment vessel with water would cool the pressure vessel from the bottom, which would likely prevent it from being destroyed by melting fuel.
However, he added that the method is not an effective way to cool the fuel rods.
Also, from the article, they suspect 2 and 3 are still leaking. That's been going on how long now? Any updates on groundwater testing there?
Well. here's an update on the ground, though not groundwater:
High radiation levels detected at Fukushima grounds a month after explosions
http://www.asahi.com/english/TKY201104250130.html2011/04/26
High levels of radiation were detected on the grounds of the Fukushima No. 1 nuclear power plant one month after hydrogen explosions spewed radioactive materials, according to Tokyo Electric Power Co.
The findings were shown in a map depicting radiation levels that TEPCO released for the first time on April 24.
Radiation levels in the air around the No. 1 and No. 3 reactor buildings were especially high, mainly because the hydrogen explosions damaged the buildings and spread radioactive materials.
I notice they refer to the piles of rubble starting to be removed, though no mention is made of radioactive materials that were reported earlier to be bulldozed on the grounds.