SoylentNews is people
SoylentNews
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 Runaway1956 on Sunday July 23 2017, @06:29PM (9 children)
Interesting idea. I wonder if it's possible, and if it's feasible. Of course, it's not enough just to make it submergible - it has to withstand the impact of tens of thousands of tons of moving water. Submarines generally don't suffer such an impact. Offhand, I'll say it's probably possible. But, I think it's probably more feasible to build further from the water, than to build a structure strong enough to remain water tight after impact.
Someone might have fun doing a computer simulation to see how your idea could be made to work!
(Score: 2) by kaszz on Sunday July 23 2017, @07:18PM (7 children)
Submarines have batteries and snorkels. Concrete can be made watertight. Water ramming can be handled using concrete blocks or rocks.
The risk with far away facilities is pipe maintenance and rupture.
(Score: 3, Informative) by Runaway1956 on Monday July 24 2017, @01:45AM (6 children)
In Winter Harbor, Main, there is a road built out to the point. It goes through the park, past the gates to the Navy installation, and out onto the point. The point has no "beach", as most people think of it. Instead, the shore is littered with huge rocks, ranging from some small enough to fit into a dump truck, up to thousands of tons. It's an awesome place to be, during a storm. You can hear the rocks moving from far off, you can feel the vibrations as they hammer against each other. Of course, you can't sit there and watch during the worst storms, because your car is likely to be thrown into the hillside behind the turnaround, or even sucked into the sea by receding water.
It isn't unheard of for a few of those huge rocks to be thrown up onto the parking area, after a bad storm. Unusual, yes, but not unheard of.
I wonder, Kaszz, if you have ever witnessed just how powerful the water is. Personally, I can't trust concrete or rocks to turn a hammerblow from the ocean.
(Score: 2) by kaszz on Monday July 24 2017, @06:33AM (5 children)
If this is a problem. Then anchor any protection as far deep down into the ground as needed. Or simply bury the facility such that a flat plane is presented horizontally towards the sea. Besides this application is mainly about tsunami and not so much wave hammering.
Btw, regarding Winter Harbor, Main. How high are the wave maximum? how fast is the wind speed?
(Score: 2) by Runaway1956 on Monday July 24 2017, @08:16AM (4 children)
The highest waves I ever saw coming in to the point were about 15 feet high. There was evidence of higher waves than that. Wind? I can't even guess, but local wind conditions have little effect on the sea conditions. I sat here for a minute, trying to figure how to convey how it feels to stand on that shoreline during a storm. Let's try this - https://en.wikipedia.org/wiki/1991_Perfect_Storm [wikipedia.org] More specifically, down the page, you'll find https://en.wikipedia.org/wiki/1991_Perfect_Storm#New_England_and_Atlantic_Canada [wikipedia.org]
Elsewhere in New England, waves up to 30 ft (9.1 m) reached as far north as Maine,[1] along with tides that were 3 ft (0.91 m) above normal.[20] Significant flooding was reported in that state, along with high winds that left areas without power. A total of 49 houses were severely damaged, 2 were destroyed,[1] and overall more than 100 were affected.[25] In Kennebunkport, the storm blew out windows and flooded the vacation home of then-President George H. W. Bush.[2] The home sustained significant damage to its first floor.[26] In Portland, tides were 3 ft (0.91 m) above normal, among the ten highest tides since record-keeping began in 1914. Along the coast, damage was worse than that caused by Hurricane Bob two months prior.[25] Across Maine, the storm left $7.9 million (1991 USD) in damage,[1] mostly in York County.[25] More than half of the damage total was from property damage, with the remainder to transportation, seawalls, and public facilities.[25] Although there were no deaths, there were two injuries in the state.
I wasn't there in '91, it's hard to say how the storms I witnessed compared to the Perfect Storm. Thirty foot seas on top of an especially high tide, and 75 mph winds hitting the shoreline have got to be pretty damned awe inspiring. People probably heard the noise, and felt the vibrations pretty far inland. Five to ten miles? Much less severe storms could be felt through the ground about two to three miles inland. At some point, of course, the sounds and vibrations of a distant shoreline phenomena is going to be drowned out by more immediate weather conditions.
(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.
(Score: 3, Informative) by TheLink on Monday July 24 2017, @06:39AM
There was another plant where they spent more and built it right: http://www.oregonlive.com/opinion/index.ssf/2012/08/how_tenacity_a_wall_saved_a_ja.html [oregonlive.com]
Thing is, it cost a president's job to do so: