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
TEPCO announced on August 13 that the in-the-ground water storage ponds at Fukushima I Nuclear Power Plant which leaked contaminated water in April were found floating maximum 40 centimeters. It is probably due to buoyancy created by groundwater flowing around the ponds. The contaminated water has been transferred to the above-the-ground tanks, and the ponds are empty. TEPCO says there is no fresh leak of contaminated water.
According to TEPCO, the Pond No.3 (56 x 45 x 6 meters) that contained highly contaminated water is floating maximum 40 centimeters, and the Pond No.4 (40 x 25 x 6 meters) that contained low-contamination water from the basements of Reactors 5 and 6 buildings is floating maximum 15 centimeters.
The Pond No.3 and the Pond No.4 are located west (mountain-side) of the reactor buildings. According to TEPCO, 1,000 tonnes of groundwater is flowing there per day, and the groundwater levels in the area where the in-the-ground ponds are located have risen by 1 meter or so since April.
As a countermeasure, TEPCO will put a 50-centimeter layer of gravel at the bottom of the ponds as weights. If the groundwater levels suddenly rise due to heavy rain, TEPCO will draw groundwater from the wells around the ponds and move the water to different ponds.
Uh... musical ponds?
Why don't they simply pump up the groundwater there and put it in these ponds?
It was just too bad and extremely short-sighted for TEPCO and NISA to use these ponds for highly contaminated waste water. They could have used these ponds to store clean groundwater before it goes anywhere near the reactor buildings and from there released into the ocean.
From TEPCO's handout for the press, 8/13/2013, Pond No.3: