Workers at the Fukushima Daiichi nuclear power plant have found that the newly-installed Advanced Liquid Processing System (ALPS) designed by Toshiba, the system which is supposed to be filtering 62 different radioactive substances out of the contaminated water being generated daily at the crippled nuclear power plant, is leaking contaminated water from a welded part of a storage tank. Officials have been unable to determine the exact amount of liquid and radioactive materials which leaked.
Discoloration found at welded edges of a leaking tank at the Fukushima Daiichi nuclear power plant.
The utility is testing the ALPS system this month, but has now been forced to halt the test-run of the system to investigate the cause of the leak. Some officials did note that faulty welds may be the cause of the problem.
Source: TEPCO
Source: NHK
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metal worker
June 17, 2013
This is simply negligent. It’s obvious that the leak was adjacent to the weld and that it’s the result of very poor practice and procedure. Where was that vaunted Japanese quality control management on this one? Can’t there be one bright spot in all this mess?
metal worker
June 20, 2013
It’s been reported at ex-SKF and Fukushima Diary that Tepco did a dye test and found two pinholes in the weld. While I can see the discoloration on the left side of the weld, just what is that on the right side? By the way, it seems to me, though I may be wrong, that this weld is ground just because of cosmetics. I would imagine it was a pretty ugly thing to begin with. The weld material itself is the area that is shiny without the pitting (pretty normal surface conditions in stainless products due to a number of circumstances and the weld isn’t exposed to those circumstances) and even in this picture the weld is uneven and not in a very straight line. Stainless (and just about all weldments) are subject to what’s called contraction craters. When one abruptly extinguishes the arc, the molten puddle solidifies at the outside edges in toward the center of the puddle. The metal, as it cools, contracts, and so will pull the molten or more mobile material (because it is hot and soft) out, leaving a void at the center. But, again, even in what’s seen on the left of the weldment in the picture, it’s hardly where one would think it would be, in the center of the weld. Then, too, I wonder if the same grinding was done on the inside, as sometimes a welder will ‘butter-up’ the crater, when in fact it still exists on the inside, gives a crevice for corrosive material to accumulate, and it will generally have oxidation on the edges of the hole, also leaving the material there in a less that ideal state. Areas such as these will eventually show up on the opposite side of the weld because of the reasons above and the fact that the material at the crater are simply thinner. The fact that the weld doesn’t appear too straight just takes it back to my first comment.