The huge storage tanks riveted together in haste at Fukushima I Nuclear Power Plant in mid 2011 to hold highly contaminated waste water after cesium absorption and reverse osmosis treatment continue to be a headache for TEPCO, though not a big one as in August this year when supposedly 300 tonnes of this waste water were suspected to have leaked from one such tank into the surrounding soil (for more, see posts on "RO waste water leak of August 2013").
Leaks found on December 21 and 22 was not the waste water but rainwater accumulated inside the concrete/steel plate barrier that surrounds the concrete pad on which these tanks stand.
How did 225 tonnes of rainwater contaminated with up to 440 Bq/L of strontium leak? From cracks in the concrete barrier and the concrete pad. Looking at the photos from TEPCO, I think I can almost tell which brand of sealants at neighborhood DIY stores that absolutely do not work as promised.
Well, let's just say TEPCO's ingenuity in emergency in April 2011 of using bath salts and saw dusts and shredded newspaper and baby diaper polymer to trace and stop the extremely radioactive water (with more than 1 Sievert/hour radiation) continues to this day.
The legal density limit for strontium in discharge water is 50 Bq/L, and TEPCO's internal standard is 10 Bq/L.
From TEPCO's photos and videos library, 12/22/2013:
and solution (note the two-level metal barriers installed this year to prevent the overflow):
More solutions using waterproof sealant, from TEPCO's 12/24/2013 photos:
Sealant along the crack:
and waterproof paint:
The Asahi article (12/24/2013) says strontium is most likely from the concrete surface. TEPCO says cesium was below detection level.
Still, I'm more optimistic about the plant these days compared to, say the first week of the accident in March 2011 when the reactor buildings were blowing up one after another with no power supply to the plant (which wasn't restored until April 4, 2011) and to the central control rooms to figure out what was going on.
Almost by sheer luck, the Spent Fuel Pool of Reactor 4 was "refilled" when the gate that separated the Spent Fuel Pool and the Reactor Well/DSP partially broke after the explosive event on March 15, 2011 that wrecked the operating floor; the water that was in the Reactor Well/DSP flooded the SFP, restoring the water level in the pool.
Despite numerous declarations and predictions by mostly overseas experts for the past two years, the Reactor 4 building is still standing, and from all measurements done so far, not even tilting or bulging or cracking beyond the design standard. (You are always free to exercise the freedom of speech and declare TEPCO is lying.)
Instead, the disaster that continues to unfold at Fukushima I Nuclear Power Plant has been of slow, whack-a-mole type since the initial explosions in March 2011. No scary enough headlines that would allow experts and bloggers to scream "disaster" and declare the world's end, but it is disheartening (partly because they seem so trivial and made worse by TEPCO's incompetence and lack of hands-on knowledge - or I should say lack of workers with hands-on knowledge and experience) nonetheless and demoralizing.
So much so that it almost makes one want an actual, huge disaster to happen at the plant.