Sunday, February 26, 2012

#Fukushima I Nuke Plant: High-Radiation Leak from the Welded Pipe in SARRY

A small leak was found in one of the two lines of Toshiba/IHI/Shaw's cesium absorption system "SARRY" on February 25, 2012. SARRY is housed inside the Miscellaneous Solid Waste Volume Reduction Treatment Building (so you don't need to scream "another frozen pipe!). TEPCO says the leak was about 10 liters.

TEPCO says the leak was at the welded part of the pipe, but looking at the second photograph it is from below the weld. The water is shooting out as if from a pinhole:

As TEPCO put it on their unofficial English handout for the press (2/25/2012):

[2nd Cesium adsorption apparatus (SARRY)]
・At 8:30 am Today (Feb. 25), TEPCO worker and partner companies’ worker found water leakage at welded part of piping at B line of 2nd Cesium adsorption apparatus (SARRY) placed on the 1st floor in Miscellaneous Solid Waste Volume Reduction Treatment Building (High Temperature Incinerator Building) of Fukushima Daiichi Nuclear Power Station. The leakage is just a drop per second and the amount of water leaked is approx. 10 litters [sic] (2m X 5m X 1mm). Those leaked water are stayed in barrier in the building and it did not leaked to out of the building. At 10:44 am, we stopped operation of SARRY and closed valve positioned in the upstream of leaked point to prevent further leakage of the water. We confirmed that the leakage was stopped at 11:10 am. Surface radiation is approx. 4-5mSv/h (2mSv/h in the back ground). We sampled the leaked water and analyzed the radioactivity concentration. The result is that I-131 was lower than the detectible limit, Ce-134 was 1.3×10^5 Bq/cm3 and Ce-137 was 1.8×10^5 Bq/cm310. The treatment of accumulated water is not affected by suspending the SARRY and there is no effect to the water injection to the reactor since there is a lot of purified water in the buffer tank.

("litters" is very cute.)

Luckily, since the once-highly contaminated water from the turbine buildings is not so highly contaminated like it used to, as it gets diluted by 500 tonnes/day groundwater that keeps coming every day into the basements of the reactor buildings and the turbine buildings. Still, the radioactivity of the leaked water was:

  • I-131: ND

  • Ce-134: 1.3 x 10^5 Bq/cubic centimeter

  • Ce-137: 1.8 x 10^5 Bq/cubic centimeter

  • Surface radiation: 4 to 5 millisieverts/hr in the 2 millisievert/hr background

When the water treatment started in June last year, the radioactivity was in the order of 10 to the power of 6 per cubic centimeter. The radioactivity is now low enough so that TEPCO doesn't need to use AREVA's co-precipitation and condensation system any more for daily operation.

TEPCO is doing what it is good at, which is small maintenance here and there for the smooth operation of a plant. The difference now is that the plant is totally broken as you see in the photos in my previous post. But tending to a bad weld that is leaking is totally within TEPCO's comfort zone, minus radiation. Strange, desolate calmness about the whole thing.


Atomfritz said...

Looks like pinhole corrosion from the tube's inside.
I also had the impression that the hole must be below the weld, but it's difficult to tell for sure from the two-dimensional photo.
Bad quality weld? Or water more aggressive than anticipated?

Anyway, this is probably not a big issue, as minor drip leaks up to 1 liter/hour are permisible in nuclear plants heat exchangers like San Onofre.

I'd be curious whether Tepco does any patrolling outside to check for any leaks in this makeshift network of plastic tubes.
I think it would be quite miraculous if no leaks to be found there.

Remember, when the trenches flooded with highly active water were discovered, it was said that was the first patrol after seven months or so.

Anonymous said...

Well, TEPCO is stuck with this mess for the next thirty years, minimum. Barring recriticality or a massive pipe failure inside the RPV in the coming few months, there will not be much of a rush to do anything anymore.

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