'Super Steel' Sought For Fusion Reactors 421
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."
Current record holder (Score:4, Informative)
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.
Re:Current record holder (Score:3, Informative)
Sorry, tungsten (pure) is not very thought. You can drill it and cut it with standard tools. Tungsten-carbide alloy is really thought.
I know because pure tungsten is used to stop radioactivity (it's 50% better than lead), and I work on that field.
Re:If it doesn't work... (Score:5, Informative)
Popular Mechanics [popularmechanics.com] explains this. Not that I think it will matter to the conspiracy crowd.
Re:If it doesn't work... (Score:5, Informative)
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.
Re:If it doesn't work... (Score:2, Informative)
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?
Re:Steel not the only material out there... (Score:4, Informative)
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.
Re:If it doesn't work... (Score:5, Informative)
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.
Re:Steel not the only material out there... (Score:1, Informative)
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.
Re:Current record holder (Score:5, Informative)
The point of this article eludes me.
You aren't the only one. If you want something that can retain it's strength at high temperatures, don't use steel. I recommend some sort of engineered ceramic, [wikipedia.org] like tungsten carbide [wikipedia.org] (which I believe is what you meant).
The article seems to ignore the fact that engineers see steel becoming weaker with heat as a benefit. If steel was always super strong at any temperature, how would you make anything out of it? Engineers currently utilize the "irregularities" (we call them dislocations) in steel to manufacture things. One such process is known as work hardening. [wikipedia.org] When certain materials, like steel, are formed (bent, rolled, etc.) at low temperature, the dislocations propagate and move. The dislocations interact with each other, like tangling up a ball of yarn, making the material stronger. The component can then be heated to make further manufacturing easier, or left in it's cold worked state to make the finished part stronger. This property of steel is utilized around the world to make very strong, and inexpensive parts. A variety of other heat treatments [wikipedia.org] are available to perform similar tasks.
In summary, the thermal properties of steel are considered a asset, because it allows us to manufacture things with high strength inexpensively. Using a material that is strong at all temperatures will increase costs. Such materials do exist but steel isn't one of them.
Disclaimer: If you find anything above factually incorrect, I was a C student in material science.
Re:I'm confused. Would steel even work? (Score:2, Informative)
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.
Re:If it doesn't work... (Score:5, Informative)
Re:If it doesn't work... (Score:4, Informative)
Re:It's Certainly a Strange Coping Mechanism (Score:3, Informative)
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
Re:If it doesn't work... (Score:3, Informative)
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.
Re:Steel not the only material out there... (Score:3, Informative)
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.
Re:Current record holder (Score:5, Informative)
What you say is largely true, but for nuclear applications you usually have a few more constraints that make steel look more attractive again.
The core of a fast breeder reactor, or the structural components of a fusion reactor, will unavoidably be exposed to a very intense flux of high energy neutrons. These neutrons can cause all kinds of defects in the material you use, ranging from dislocating atoms to changing their elements due to nuclear transmutations, and whatever material you use must be able to withstand the irradiation. Many nickel alloys fail for this reason.
Also any material which absorbs a lot of neutrons, or reduces their energy, is going to cause issues. If you use Nitrogen in a ceramic it may need to be enriched to prevent excessive Carbon-14 production as an example. Some elements, like Lithium, Cobalt and Bismuth, produce very troublesome radioactive isotopes when irradiated. Carbon is quite good, and carbon based ceramics are heavily researched, but it is a rather light nucleus, and will slow neutrons that scatter against it. This may be desirable in a thermal reactor, but for fusion reactors and fast breeder reactors you want a very high neutron energy to enable the destruction of long lived waste isotopes, and this means you need to limit the amount of carbon present in your core and structural materials.
Furthermore materials to be used for a reactor need to go through very time consuming and thorough testing program , and this is why steels are very attractive candidates since much of the necessary data already exists. Sure, using something like Silicon Carbide may be worth investigating ( and it is indeed being investigated for a number or reactor designs ) , but even thou it has good thermal conductivity, corrosion resistance and thermal stability, it is not immediately clear that it will withstand the radiation environment, it's fracture hardness is less than ideal, and you need to be able to reliably produce it to the strict standards required by the nuclear industry. To develop and test a material for nuclear applications is a very expensive procedure, so if you can use materials that you already have data for, it will dramatically reduce the necessary research and development costs.
Also, as usual there is a cost issue of the material itself. Tungsten, with its high melting point, good strength at elevated temperatures, and low neutron absorption is very attractive from technological aspects, but building an entire reactor from it will hurt your bank account.
gw bush doesn't purposefully kill civilians (Score:3, Informative)
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
Re:If it doesn't work... (Score:3, Informative)
http://www.youtube.com/results?search_query=9%2F11+molten+metal&search_type=&aq=f [youtube.com]
Re:If it doesn't work... (Score:3, Informative)
Re:If it doesn't work... (Score:3, Informative)
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.
Re:Why are they not using Carbon Composites? (Score:3, Informative)
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.
Re:If it doesn't work... (Score:3, Informative)
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/ [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