Published: June 8th, 2012 at 11:33 am ET
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The Protection Platform Added on Unit 4 Spent Fuel Pool at Fukushima Daiichi Power Station
Tepco
June 8, 2012
1. Purpose
The protection platform was added on the existing protection float to prevent debris falling into the spent fuel pool and ensure a higher level of safety.
The protection platform is assembled on the ground and then installed on the spent fuel pool utilizing large heavy machinery.
- Size (Approx.): 11.0m (length] x 13.7m (width)
- Weight: Approx. 60 tons
See also:
- April 23, 2012: White sheets covering surface of Spent Fuel Pool No. 4 seen during top official's tour of Fukushima Daiichi (PHOTO)
- April 16, 2012: Report: Tepco will start covering No. 4 Spent Fuel Pool tomorrow
Published: June 8th, 2012 at 11:33 am ET
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sending...
let's add 60 tons of weight onto a shaky broken structure watson. and lets cover the pool so we cannot access the rods sherlock.
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OT- for Saturday Night visitors to this thread
tonight SAT 6/9 10pm is the 'Fukushima special' with Gunderson, Blume, Apsley and Dale, on CoasttoCoastam radio. First national radio discussion I've seen during the 14 months, going to 550 stations nationwide, and there usually is a call-in hour for direct questions to the guests. If you can get your call in, and talk to Arnie or the others, you will have 20-some million mostly Fukushima-unaware listeners who may benefit in various ways from your questions and comments, and the following discussion:
http://www.coasttocoastam.com/show/2012/06/09
thanks for the heads up jump-ball.
One More Saturday Night All … Cheers to Fuku & everyone
http://www.youtube.com/watch?v=OWPBgg9i3Mc&feature=fvwrel
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60 tons of addition weight?
Shield your eyes from the madness..folks.
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Planning to, or already did? ..are live cameras showing this?
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It's not clear from that handout, if they already installed it. In one sentence, they say "Protection float covering the spent fuel pool (current condition) [!]" and in another one they say "The protection platform was [!] added [...]"… no timelines, no dates, no clear information.
But what is it good for – except for keeping debris from falling into the pool? Which as it turns out is not necessary, because "Area to be removed [pretty soon i guess]", is the only source for debris from above… and therefore it won't be of any danger for very much longer.
If the pool _collapses_ on the other hand, it will further complicate the situation for TEPCO if they want to spray their announced "concrete mixture" (see archive) on it to prevent overheating and the ignition of a circonium fire. It also makes it more difficult to remove fuel or the fallen crane, if a 60 tons shielding plate is atop of the pool, right? So… assuming, that the whole "protection" is not simply a PR measure: What is that (metal, as it seems) plate REALLY good for? Maybe they hope, that it will hinder gamma radiation skyshine, if the pool _doesn't collapse_ but simply _fall dry_ due to major water leakage (without the risk of a circonium fire in that case – as reported by Asahi TV).
But would that guarantee sufficient protection for workers against the overall gamma radiation dose coming through the pool walls in that situation to stay on site for a reasonable length of time? I'm…
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… sceptical about that.
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The Japanese language does not have a future tense naturally, so it often translates into present or sometimes past tense. I think this MIGHT explain why the article is so unclear.
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"Stupid is as stupid does." Probably some pro-nuclear MIT engineer who came up with this idea…brilliant!
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Wait-they can place a 60t cover but cant lift a fuel rod assembly? BS meter is goin off again.You cant see shit from tempco live cam,its pointing at #1-http://blog.alexanderhiggins.com/TEPCO-TBS-JNN-Fukushima-Live-HD-Video-Stream-Webcam-Feed.html
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That was my though. If they can lift 60 tons, why not lift the 35 ton crane that fell onto the rods out?
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Great question why not lift crane off stacks? Well maybe not sure but watched sumthin about the spacing in the pool being critical. That is the rods without their control rod inserts are extreemly dangerous if moved as if 2 rods get too close the reaction will start melting the cladding witch has sum metal that helps with insulation zirc? anyway my bet is that the rods are all scrambled and half cooked by the fire they had for 2 weeks in the pool per cam and of course the crane sitting on all these supper time bombs if they so much as start to lean again near each other- Cant move um cant cover them with anything cept a lite tarp–wait this just in… correction make that a 60 ton ELE coffin. Tea i need tea
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Seems like a lot of weight to add to one side of an already unstable building.
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This gives new meaning to COVER UP….
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I thought they could not get near the thing with robots or people?…
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Not true.. even reporters were standing next to the pool ~2 weeks ago.
As long, as there is enough water in the pools, the rods are perfectly shielded. If not (anymore), you'll get extreme doses within hundreds of meters if you have no sufficient secondary shielding.
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I believe that they would say reasonably shielded not perfectly shielded. Emissions of even heavily shielded facilities can still be detected by spacecraft.
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That's inside R1-3
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it's a 1000 Cubic Feet of water, so figure about a foot of depth in the pool.
That said it's stupid, because they need to get the fuel out, not cover it up.
Typical Japanese.
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The plan is to keep the fuel rods there for around a decade, so they cool down. Nobody is talking about removing them at this point.
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@patb2009: your statement "Typical Japanese" is offensive and off the mark. I believe most Japanese would agree that TEPCO is f*cked. Perhaps "typical corporation" would be more accurate. It pains me when people get self-righteous and point fingers at other races/cultures. Last time I checked, Americans started this mess and now every "first world" nation has a big piece of this action (nuclear power/weapons, military industrial capitalists, etc.), with "developing nations" lining up for their slice of the nuclear pie.
It seems to be a human problem and I canʻt imagine things going much better if this multiple meltdown happened in the US or the UK. The Japanese nuclear program is inextricably tied to the American nuclear program, which is a major reason the US is complicit in the ʻcoverupʻ.
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+1 hanaloa. It's important to point out these differences.
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We came about a duck's wake from a meltdown in Ft Calhoun that would have lost Iowa, Missouri, Illinois, and others last year.
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I agree and was also struck by the offensive nature of this comment, "typical Japanese".
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We all see how much this specific unit has convected all year. This is likely a lead enforcement / shield. And as mentioned above in no way a debrie shield. As there is. No specific roof / danger threatening the unit at this time. Also the roof would likely take the shape of a pyramid and not a flank if that were actually the case. As they offer more structurally sound enforcement than the latter…
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Reality check: Why install a hard cover? This is going to be a construction project, to add a reinforced concrete Frame to prop up Building4, and to serve as the platform for an overhead crane to finally lift fuel rods out. Needs a cover so men and material don't fall into SFP4 during construction.
Why 60 tons? The cover is 11m X 13.7m, and will weigh 60 tons. Has to be self supporting so as not to disturbe contents of SFP4 with support columns.
Does cover have lead? I'd include lead to protect workers from radiation in SFP4 as they build the Frame. Would be pretty easy to calculate what the weight of a self-supporting steel structure this size would be, the, see how much of the 60 tons is left over for lead. Any engineers out there?
Remaining question is will TEPCO bother to install a system to keep track of water depth in SFP4 while covered, and will they be able to locate the leak that is currently draining the pool?
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phil,
How do you build a house on top of another house whose foundation and walls are cracked?
Engineers, anyone?
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"[The 'Protection Platform' in the above image] is going to be a construction project, to [...] serve as the platform for an overhead crane to finally lift fuel rods out."
I'd rather think, that's what they installed the "Small heavy machinery Platform for heavy machinery (already installed)" for. Stupid name… but… interesting freshly added feature to block #4, i'd say.
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Lead will shield against some, but not all isotopes.
Read more: http://wiki.answers.com/Q/Why_does_lead_block_radioactivity#ixzz1xFHYxNRV
Answer:
Lead is applied as shielding to block (attenuate is the word we prefer) gamma rays. This form of radiation is electromagnetic in nature, and not particulate (composed of particles). Materials of high density (and lead is fairly high) are better at attenuating gamma rays than less dense materials. Additionally, lead is cheap and easy to work with. You've doubtless heard of lead being used to shield against X-rays, which are just a bit lower in frequency than the gamma rays.
It is the "close spacing" of the atoms and the "bigness" of the atomic nuclei of lead that make it good for use in gamma ray shielding. Gamma rays "cut right through" electron clouds around atoms, and only the nuclei of atoms really give the gamma ray something to interact with. As regards particles, lead will stop alpha and beta radiation with ease, but so will a sheet of aluminum foil. Lead isn't that great at stopping neutron radiation. Shielding for neutrons requires atoms with small nuclei, so lead isn't so hot in that application.
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BTW, that's a quote from Wiki Answers, above re: shielding.
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15 months now…
… STILL NO COVER FOR SFP3.
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This is going to take a major undertaking. What is going on now is a bunch of lunitics trying to save what was lost long ago. They have been nickle and dimeing this thing like it was a rental they didn't like and were getting rid of after the lease had expired. This accident is so complex that no man knows what to do with it. Knee jerk reactions is all I'm seeing. The U.S. paid a huge sum for the sarcophagus in the former U.S.S.R. Time to kick down in a big way, don't you think? Move in the Army Corps or someone and lets get moving some mountains.
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OT, but maybe worth listening to is the 'Fukushima special' tomorrow night SAT 6-9 10pm with Gunderson, Blume, Apsley and Dale, on CoasttoCoastam radio. First full radio discussion I've seen during the 14 months:
http://www.coasttocoastam.com/show/2012/06/09
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i read that they were going to removed new fuel racks asap???
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yes they will install the 60 ton cover first to make sure it fits then take it off and remove the fuel racks? hu, say what?
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They are planning to build a building around and over the current one so they can install a new fuel crane. This is to keep building materials out during construction
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60 ton lid to keep building dust out on top of a fatally fractured and advanced radioaging crippled structure? Yea rite ok smokey that makes no sense just kick it over if ur that stupid at least we will all no how long we got Wow friggin brillant
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@sharp2197 Bet they will not only "keep Building materials out" but also any media cameras. Sounds like they are trying to do work. OR maybe just "doing work" and then seem to be proactive (little late huh?). Anyone think this will work?
One picture comes to mind, a 60 ton square projectile being exploded into the atmosphere…a real BIG BANG theory….
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As some have said this is protection for the fuel inside the pool from construction materials as they build a new crane to move fuel. They can not just use any crane to move the bundles because it is a very exacting procedure. The fuel bundles are densely packed into these modified fuel racks that have been installed to allow more fuel bundle storage than the original design.
The original fuel handling machine that was destroyed has many features: underwater camera, locking devices.and limit switches that are essential for moving fuel. To remove a 14 foot long bundle from the fuel racks requires precision with an inch or so.
There is no danger from the pool unless the water level drops. One foot of water reduces a gamma source by 50%.
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Thanks for the assessment. TEPCO wrote about protection against "debris" in their PDF, so i took that for granted. That's why i speculated about a more subtle explanation for the shielding plate, than just physical shielding – because there is not much "debris" left near and above the pool.
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Don't take falling objects as minor. The first nuclear accident was the result of a brick falling on fuel. In the case of the first accident, neutron reflective bricks were placed around a fuel pit so that the reflective material would act as though a much larger mass of fuel was present. In the case of Fukushima, such a large mass of fuel is already gathered that even a small item such as a bolt falling could start a localized criticality that could destabilize the rest of the fuel. Should such an event occur, a heavy mass shield such as lead foil or other materials over steel would reduce the skyshine.
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Given the issues that have been continuously raised lately concerned not only the soundness of the structures that remain at Reactor #4 and that are supporting its fuel pool, but also concerning the levelness/stability of the ground beneath the reactors, isn't putting an extra 60-tons of weight over a fairly small area (relative to the entire building) at the very least kind of risky, if not outright dangerous? Spent Fuel Pool#3 has its fuel crane lying atop the fuel racks inside the pool itself, weighing in at about 30 tons, but its structural integrity seems to be in much better shape by comparison..
Although I can see where this plan would be useful if there weren't all the structural problems, their presence makes this baffling to me. But that could well be due to my ignorance concerning the constructional realities at Fukushima, among other things.
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