It's one thing after another at Fukushima I Nuclear Power Plant. Today, it's the floating ponds.
Remember those in-the-ground water storage ponds that leaked back in April? They were originally constructed for storage of treated water. But as TEPCO was running out of above-the-ground steel tanks, TEPCO consulted with the then-regulator Nuclear and Industrial Safety Agency bureaucrats and experts in August 2012. NISA officially allowed the use of these in-the-ground water storage ponds for highly contaminated, post-RO (reverse osmosis) waste water with high beta.
The ponds were lined with thin liners, as if they were garden ponds, and the water leaked. That was not what the elites at TEPCO and NISA were expected. TEPCO was forced to move the waste water into above-the-ground steel tanks.
These ponds have stood empty since May/June. Well of course they float.
Now, TEPCO announced that they found two of these ponds "floating", or bulging in the center. TEPCO doesn't say why, but Asahi Shinbun (8/13/2013) speculates it may be from the groundwater pressure:
In-the-ground water storage ponds float 40 centimeters [max] at Fukushima I Nuke Plant, probably due to buoyancy from groundwater