Slashdot Mirror
'Super Steel' Sought For Fusion Reactors
Smivs writes "New research shows how
steel will fail at high temperatures because of the magnetic properties of the metal.
Scientists say an understanding of how the Twin Towers collapsed will help them develop the materials needed to build fusion reactors.
The New York buildings fell when their steel backbones lost strength in the fires that followed the plane impacts.
Dr Sergei Dudarev told the British Association Science Festival that improved steels were now being sought.
The principal scientist at the United Kingdom Atomic Energy Authority (UKAEA) said one of the first applications for these better performing metals would be in the wall linings of fusion reactors."
The highest performing 'steel' currently seems to be what's called '"maraging steel', but calling it steel seems a bit odd since the alloy contains next to no carbon.
Tungsten is a lot tougher than just about any steel, and it's often used the coating alloys of for example drill bits used in industrial CNC applications.
The point of this article eludes me.
All rites reversed 2010
Popular Mechanics explains this. Not that I think it will matter to the conspiracy crowd.
See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
Yeah. The Twin Towers should have toppled over, but instead, they blew up like a building that was being imploded for demolition.
It figures that today of all days would bring out the conspiracy theories. So you're saying that a building weighing probably millions of tons could topple over a specific and single pivot point?
Also, the melting point of the steel used in the Twin Towers is actually about 400 degrees HOTTER than the temperature at which jet fuel burns.
If the jet fuel is out in the open, where heat can dissipate, that would be true. But this was a whole LOT of fuel in an enclosed space, so as the fuel burnt, the steel could keep getting hotter and hotter. Burning fuel = energy released. If the energy cant escape, it builds up in the form of heat.
The Twin Towers would also be the first example in history of a steel building where the steel failed due to fire.
And the thousands of tons that slammed into it at high velocity had nothing to do with it? (Actually, I'm guessing that had something to do with it, but not sure.) If you're spinning theories here, you need to stick to WTC building 7, the collapse of which was thoroughly studied, and concluded that fire alone was the result of it's collapse.
$7.95/mo, 200 GB disk, 2TBxfer, MySQL, PHP, RoR.
Also, the melting point of the steel used in the Twin Towers is actually about 400 degrees HOTTER than the temperature at which jet fuel burns.
The steel doesn't need to melt to cause catastrophic failure... which is why, for instance, steel support beams on a bridge can collapse when a fuel tanker explodes.
The Twin Towers would also be the first example in history of a steel building where the steel failed due to fire.
Yeah... well, it was a bit more than a normal fire, wasn't it?
Actually iron is less abundant than aluminum, but it has the advantage of being readily mined, refined, and made into structural steel.
The earth's crust is 61% silica, 16% alumina, 7% rust (iron oxide component of iron ore), 6% line, 5% magnesia, and 5% other stuff. The reason aluminum alloy does not predominate in the structures we build has more to do with the difficulty of smelting, refining, alloying, and heat treating it than its suitability. The mirror image is the great ease of producing ready to use steel I-beams from raw iron ore.
And the thousands of tons that slammed into it at high velocity had nothing to do with it?
NOVA recently did a special about this. Apparently the NIST investigation concluded that the impact of the jets stripped away a lot of the fire-proofing material that should have protected the steel.
Once the steel was exposed to all that heat it was only a matter of time before it failed. It never melted either -- it became flexible and eventually failed as a result.
I want peace on earth and goodwill toward man.
We are the United States Government! We don't do that sort of thing.
The reason they want to use steel, is that to most of the world outside of civil engineering, there is only 1 material to make things out of (steel). In civil engineering there is steel and steel reinforced concrete. There is no other reason to use steel.
Back in 1983, I did a literature survey on technical ceramics (SiC, Si3N4, ...) which included fusion reactor use. A first wall of carbon in the event of a loss of coolant accident (LOCA) would see no temperature excursion. A first wall of SiC would see a temperature excursion that would not exceed the melting point. A first wall of steel would flash to vapour in its temperature excursion. We do not need steel for a fusion reactor first wall.
As posted above, I don't know about vanadium. I've certainly not seen a lot of talk about it. The last I heard, ITER will have a main chamber first wall of beryllium, and a divertor made from graphite and tungsten (i think tungsten, maybe moly). Vanadium is relatively low-z for a metal and has a high melting point - score. But isn't it soft? So it would probably be used in some alloy.
Mind you, nobody wants an 'all metal machine'. Steel, tungsten, moly, or anything else. Performance isn't that good. While the vacuum vessel and other structural components will be built out of fancy steel alloys, steel, inconel, etc, the plasma facing components are usually something else. Graphite is quite popular. JET uses beryllium coatings on something. ITER is going to have (at the moment) beryllium tiles for most of the interior, with a smattering of tungsten and graphite in key locations. More cutting edge research is looking into using liquid lithium, which I think is very promising (I'm biased).
Impurities are the name of the game. We want to dump energy into the fuel, deuterium and tritium, not into whatever comes off the first wall. Refractory materials have lower sputtering coefficients, so less impurities enter the plasma, *but* plasmas a very intolerant of high-z impurities. So the lower the atomic number, the better. High-Z materials have a lot more electrons to ionize, so you end up just dumping all your energy into the impurities and letting it radiate away instead of getting your D+T up to 10's of keV in temperature.
The jet fuel had almost nothing to do with the collapse other than it was a big match that set everything else on fire. The vast majority of the fuel was consumed in the initial fireaball or within a few minutes of the crash. The critical part was the removal of fire protection and the severing of the sprinkler stack. The solution is a more robust and adhesive fire coating (like foam bead containing cement with polymer binders added to the liquid portion) and redundant sprinkler stacks. NIST estimates the cost increase to be between 2 and 5 percent for ALL of their building code enhancement guidelines including the biggest cost of increase emergency stairwell size. To me this seems like a small price to pay for general emergency preparedness and can most likely be offset over the lifetime of the building through decreased insurance premiums.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
Yes, while it won't melt at the temperatures it was exposed to in the twin towers, it is at less than 50% strength because of the heat.
http://en.wikipedia.org/wiki/World_Trade_Center#Structural_design
"The core of each tower was a rectangular area 87 by 135 feet (27 by 41 m) and contained 47 steel columns running from the bedrock to the top of the tower.[6] The columns tapered with height, and consisted of welded box sections at lower floors and rolled wide-flange sections at upper floors."
there is a citation in this block of text on the wikipedia page.
remember, mods, it's only insightful if it's true
(1.21 gigawatts) / (88 miles per hour) = 30 757 874 newtons
If those beams were significantly superior
Strength is not the only consideration: cost is a large part of it. And steel costs way, way less than timber for equivalent strength.
[ home ]
After a tour I was given of the MIT Tokamak, the professor indicated that the problem with fusion reactors wasn't heat, or even fusion. it was neutrons.
Apprently, the reactor is flooded with neutrons during the fusion 'events', and over time it will turn whatever 'steel' the reactor cell is made of into a porous sponge, that may collapse. If it didn't (maybe engineered to stay standing while highly porous) it would be next to impossible to dispose of the neutron-bombarded material.
He indicated that the ideal material was silicon carbide (SiC). the problem? no one knows how to machine it yet.
the funniest thing he said? I asked him when he thought we'd have fusion reactors. He said (I paraphrase) the he started in fusion energy in the early seventies - we were 25 years from a commercial reactor. now, 30-odd years later, we're 50 years away...
an aside - the tokamak is powered by a mind-bogglingly huge flywheel. several megawatts (i think) awe. some.
he certainly mistakenly kills civilians with his policies, certainly. and for this there is remorse and attempt at restitution. do you see al qaeda feeling sorry for killing innocents?
not that i agree with gw bush. not that i don't think gw bush is a complete moron
but to equate what gw bush does with what a group that tries to kill complete innocents on purpose and by surprise is not intellectually honest of you
let's put it this way:
1. guy falls asleep behind a wheel of a truck and crashes into a school bus, killing 10. he feels absolutely awful about it
2. guy purposefully tracks school buses coming and going, carefully calculating and planning for months when to strike and kill as many kids as possible, but he only kills 5
guy #1 kills 2x more than guy #2. but who is more evil? it is why in most societies there is a legal difference between murder and manslaughter. one is evil, the other is stupid. gw bush most certainly is not a terrorist, just a retard
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
Really? I thought it was pretty common knowledge. A quick search for '9/11 molten metal' on youtube returned quite a few results. I didn't bother to watch them all to find a 'particularly good' one, but there's lots to see if you're interested.
http://www.youtube.com/results?search_query=9%2F11+molten+metal&search_type=&aq=f
Check out my lame java blog at www.javachopshop.com
The most convincing argument for a conspiracy to me was the guy who did the math and basically showed that the floors below the impact provided practically zero resistance to the fall because the top of the building accelerated as if it were in free fall. You can fairly simply do the time calculations yourself by analyzing any of a dozen videos of the collapse and looking up how tall the building was. This would lead a conspiracy theorist to believe that the lower floors were 'detonated'. If they were largely intact (which they should have been) then the pancaking effect would've slowed the fall quite a bit.
Check out my lame java blog at www.javachopshop.com
1. No steel builing has ever collapsed due to a fire.
The WTC is by a huge margin the tallest man-made structure ever to collapse. There's a huge difference between a 10-story steel building and a 100+ story one.
2. The WTC 7 was not hit by a plane and collapsed, according to NIST 'due to a fire'.
See above. It had significant structural damage from falling debris, which contributed (along with fire) to the collapse.
1. The government explicitly forbit independent investigation of ground zero basically shipping most of the evidence on the site to be smelted - possibly to make the burden of proof on conspiracy theorists to be especially burdensome.
The words "these are facts" should never, ever be followed by the word "possibly."
2. Several witnesses report hearing loud explosions on the WTC before any planes hit.
Okay so if the explosions happened before the planes hit, why didn't the buildings collapse immediately? I thought the bombs supposedly went off after the planes hit and caused the collapse? Were these first bombs duds?
3. The opinions ( not fact, cause I can distinguish between those two ) of many engineers and scientists - none paid by the government, in stark contrast to 'not all paid by' - that it looked the textbook case of controlled demolition.
I'd call it "several." But sure, call it "many" if you like.
4. The 9/11 Comission report didn't even acknowledge WTC 7's existence. In a healthy democracy, that would be as admission of guilt, in my opinion. Since it's obvious that that part of the disaster DID NOT go according to plan.
But you're suggesting that WTC 7 was intentionally demolished with explosives. Which obviously worked. So how did this "NOT go according to plan"? Jesus effing Christ, at least keep your crackpot theories consistent with each other.
I do agree with a previous post I saw which suggests engineered ceramics. Ceramics are very good refractory materials, as they retain much more strength and oxidation resistance at high temperatures than steel, or for that matter, nearly all metals. They're also most likely going to be much, much cheaper than any metal engineered for this application. Steel doesn't fit the bill yet, and it would probably take a lot of research to figure out new heat-treatment methods to get it there. Some more exotic metals like some in the platinum group might look attractive until you see the price tag.
OTOH, as someone else pointed out, WTC 7 was NOT hit by a plane, and IT imploded right after its new owner was overheard on a cell phone by several people and a television news crew saying the words 'pull it', which is construction industry jargon for 'ignite the explosives'.
Alternatively, the guy could have been talking about pulling out the teams of firefighters that were trying to put out massive fires in WTC7, in order to avoid the kind of fatalities that happened in the two main towers.
I highly recommend looking at this site: http://911myths.com/. It's got a /lot/ of extra info on top of the crap you get fed in things like Loose Change, including many many snippets of video footage, pictures (taken from different angles to the ones shown by most of the conspiracy theorists), and lots and lots of examples of 911 conspiracy theories being based on highly selective evidence, dubious editing and egregious misquoting of people. Well worth the couple of days of intermittent reading it takes to go through the site.
himi
My very own DeCSS mirror.