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New images show what is likely to be melted nuclear fuel hanging from inside one of Japan's wrecked Fukushima reactors, a potential milestone in the cleanup of one of the worst atomic disasters in history.
Tokyo Electric Power Co. Holdings Inc., Japan's biggest utility, released images on Friday showing a hardened black, grey and orange substance that dripped from the bottom of the No. 3 reactor pressure vessel at Fukushima, which is likely to contain melted fuel, according to Takahiro Kimoto, an official at the company. The company sent a Toshiba-designed robot, which can swim and resembles a submarine, to explore the inside of the reactor for the first time on July 19.
"Never before have we taken such clear pictures of what could be melted fuel," Kimoto said at a press briefing that began at 9 p.m. Friday in Tokyo, noting that it would take time to analyze and confirm whether it is actually fuel. "We believe that the fuel melted and mixed with the metal directly underneath it. And it is highly likely that we have filmed that on Friday."
(Score: 2) by kaszz on Monday July 24 2017, @10:27AM (3 children)
15 feet high = 4.6 m
Assuming a sine wave 0..pi and a attack surface at half height that would mean something like 39 kPa on the half ballpark with a fighter jet engine running full throttle. Surely a structure can be built to handle that?
A 1 meter width wave would have the mass of circa 9200 kg, that is a lot but impossible to handle?
The load case would be pushing a specific pressure upon a structure and then relying on that the foundation would not fracture due to opposite forces horizontally. Don't recall the math for this. Maybe someone else have the ballpark for concrete.
75 mph = 33 m/s
That is something like 694 Pa (71 kg on one square meter). Possible to handle too?
(Score: 2) by Runaway1956 on Monday July 24 2017, @12:23PM (1 child)
Maybe the structure can handle it. But, something that needs to be factored in, is the entire front will be hit. If you have half a mile of bulwarks, all of that half mile will come under the same pressure, and probably all at the same time. If there is any difference in timing, it will be slight.
And, I have to bring up the canal that failed in New Orleans, after Katrina. The wall didn't have to withstand a frontal assault, and there should have been no reason for it to fail. Except, water and sewer department crews had performed maintenance some years earlier. They lifted some sections of retaining wall out of the canal, then replaced them, without removing the soil and repacking that soil. The wall was undermined by the pressure going under the wall.
If concrete is the solution, then that wall must be dug in deep, and the earth stabilized around the wall after it is poured. I suspect that the structure should look something like a buttress dam, when finished - https://en.wikipedia.org/wiki/Buttress_dam [wikipedia.org]
Personally, I don't have the formulas or the math skills to figure out just what is needed here. All I can do, is bear witness that water can, and does, defeat some of man's best laid plans. As often as not, those defeats are the responsibility of bean counters, rather than the engineers. If accountants tell you that you CANNOT build to the specs you want, then what? If you don't build to the specs approved by the money-counters, then someone else will.
One thing I know for sure is, the further from the shore, the less force the water will carry when it finally reaches the structure. And, the higher you build, the less likely that the water will even reach your structure. Distance and elevation are almost free - I would take advantage of them, as much as possible.
TheLink supplied this link in his comment: http://www.oregonlive.com/opinion/index.ssf/2012/08/how_tenacity_a_wall_saved_a_ja.html [oregonlive.com] You are correct, in that walls work. But, the article is all about the fight to have the wall built RIGHT, rather than cheaply.
(Score: 2) by kaszz on Tuesday July 25 2017, @04:39PM
It won't matter if the entire front is hammered. As long as each surface of it is supported by a proper anchor. It should preferably have some wave break ahead which can have slightly less horizontal load bearing capacity.
The walls in New Orleans (re Katrina) had insufficient foundation due to insufficient maintenance.. ie bean counters in high government.
Concrete or rock, structural integrity and anchoring as per strict calculation is everything more or less.
Bean counters can be exposed to the public to make them do the right thing. Not that the public is that bright..
The Japanese tsunami made it obvious that distance is not much of a protection. But elevation on solid foundation is. The alternative being solid foundation and water tight compartment.
Onagawa plant proves that stubborn engineering is the way ;)
The hard thing is to repeat that feat.
Anyway Yasuzaemon Matsunaga [ndl.go.jp] (1875 - 1971) trained Yanosuke Hirai (1902 - 1986), that trained Tatsuji Oshima (1930 - ).
So true!
(Score: 2) by Runaway1956 on Monday July 24 2017, @12:28PM
Also, scroll down to the links supplied by requerdanos. Elevation and distance played a role at Fukishima, in that the generators were placed in the basements.