From what I've read, the salts in use are not corrosive. Proliferation risk is on the order of 1% as high as light water reactors. I would argue that the reason chemical plants are more accident prone is that there is less care being taken. On site processing of the liquid is considered much more straightforward and easier than what is presently required at light water plants.
A major advantage of LFTRs, and (I speculate) a major reason why the commercial companies haven't pursued them to date is that Westinghouse and GE nuclear divisions' major revenues are from manufacturing and reprocessing the very expensive fuel rods. That business goes away when the raw material is essentially a simple commodity. LFTRs could be the death knell of the nuclear fuel business. LFTRs are expected to be able to 'burn up' all of the existing high level nuclear waste, fissionable material in spent fuel rods, etc. - greatly reducing the present problem with spent fuel rods getting stacked at every power plant now. Would we still need Yucca Flat? Open question.
Considering that freight cars of red fuming nitric acid and other much more nasty chemicals are routinely shipped around the country and the world in train car loads on a daily basis, I don't think the chemistry in the LFTRs is at all a signficant issue - and the LFTR runs at under 100 PSI.
I don't recall if the LFTR liquid is solid at room temp. I did read that pure Thorium tetrafluoride melts at 1100C, but the liquid is not pure ThFl4.
My recollection from quite a bit of reading in this area was that the new head of AEC whose name I forget, besides actually disliking the guy running the MSR experiment, also did not like the fact that the MSR did not produce enough bomb material, while the liquid metal fast breeder reactor (LMFBR) did. They had a budget cut (Nixon) and decided to put all the money into the LMFBR. Disagreements ensued and the MSR guy was actually fired by AEC. The LFTR is projected to produce less than 1% as much highly radioactive waste, and is generally considered a useful system for burning up all that stuff and getting rid of it.
I believe that theoretically an LFTR could run as high as 1500C, but there are limitations due to having to actually build something that could withstand that temperature. Pure thorium tetrafluoride melts at 1100C and boils at 1600C (according to wikipedia, of course).
The fuel expands as it gets hot, reducing the density and fission rate - it's self moderating, and without a continued source of trigger neutrons the reaction automatically damps out.
Nice thing about Thorium is it essentially doesn't do that. There's a bit of that going on inside the reactor but it's self-damping. Thorium by itself is very faintly radioactive, releasing alpha particles. The LFTR creates less than 1% as much waste as a light water reactor - or at least according to theory. See this article for more info on advantages and disadvantages.
The nice thing about the LFTR is that the system is under only about 15-50 PSI pressure (same as household water systems), the Thorium is not very radioactive (by itself it just puts out alpha particles, but there is harder stuff going on inside), the molten salt formula can be relatively stable (although the most common plan at present does include Beryllium which is nasty stuff). the reaction doesn't generate explosive gases, and the reaction stops on its own when you remove the power. So the accident potential is a couple orders of magnitude smaller than the classic light water fission reactors. This article covers most of the topics, and has links to several more.
Another nice thing - Thorium is essentially 100% fuel, where Uranium is naturally only about 1% fuel and has to be enriched by an expensive and dangerous process, such as the gas centrifuges being used by Iran. So it's said that 500 tons of Thorium could provide all of the US electrical needs for a year, and the US has 64000 tons of known reserves - that would be 128 years worth of fuel. (Thorium is, in fact, a rather problematical waste product from mining and refining rare earth elements, with which it's often found.)
Actually there's a fairly simple fusion reactor that you can build on your tabletop. It even works, but it doesn't produce more energy than it consumes. The Philo T. Farnsworth mentioned is also regarded as the best candidate as the original inventor of TV. The Wikipedia article also has links to some other methods.
Approximate quote from a guy whose name I forget, at Siggraph 1980. He was at JPL at the time, later went to work at the newly-formed Pixar (or was it Industrial Light and Magic? I forget), got bored and went back to JPL. He was the first person I know of to create and demonstrate what he called 'inbetweening', now called morphing, used in various JPL CG videos: "Computer graphics, the industry where the technology gets better while the hair gets shorter."
That was the same period when the Harvard computer graphics gurus could be depended on to be wearing three-piece suits and tennis shoes. And one of the hottest geeks at Tektronix was believed to essentially never wash his t-shirt - singular! He was on the international Pascal standards committee, IIRC.
I might also include the remark from Richard Stallmann, about how in the 1960s at MIT there were a dozen or two computer science students, of which 10 were really good; and years later there were a couple hundred computer science students, of which about 10 were really good.
Neither of these is an exact quote; hopefully the gist survives.
I'm reminded of my high school chemistry class. One whole side of the classroom was glass with floor to ceiling drapes, which were peppered from top to bottom and the full length with tiny little holes from some experiment that didn't go according to plan. Wish I had been there!:D
Indeed. Try to find a chemistry set that contains potassium permanganate and glycerin these days, much less the ingredients for gunpowder. We had science fair experiments in sixth grade that today would get you into the newspapers and black SUVs showing up. And going back before my time, my somewhat older neighbor built a pipe cannon back in the 1940s that fired rocks over a mile.
But there's always the Internet, where you can find the free e-book "Ignition" by John Clark. Very funny history of liquid rocket propellants from the 1940s through to the early 1970s. Any discipline where red fuming nitric acid is considered one of the more stable, tractable ingredients is going to be interesting. (compare with Chlorine Trifluoride)
Much like reading your posts, along with that pathetic signature of yours
Actually the sig does have an arguable point. There is a substantial, and I would say, growing minority, mostly libertarians, who think that Lincoln was not the grand hero that we are taught in school. For starters, he suspended Habeus Corpus, despite believing he had no legal right to do so. It is apparent that he himself believed that the states had a right to secede. And various of his acts were the first step toward the diminution of the importance and sovereignty of the individual states, including instituting the first federal income tax. Others than myself could argue this point, I'm really not up on the details.
I don't agree with that position. For myself, I feel that, like all humans, Lincoln had his good and bad aspects. I do regret that this was the period when the Northern banking and financial establishment essentially took control of the direction of the nation. While it was being misused at the time, the concept of States' Rights is an important one, that has been continuously whittled away until today when the Commerce Clause is used to basically get federal priority over everything including what crops I can grow or not grow (if I had a farm) and whether I wear a seatbelt and how fast I can drive.
There is yet another point of view. I once read a book called "The Lincoln Conspiracy", which asserted that the assassination (originally planned as a kidnap and impeachment) was planned by a cabal lead by Edwin M. Stanton to prevent what they saw as overly liberal plans for the reconstruction period. This is probably closer to fiction than fact, but it was fascinating to read.
There are numerous historical precedents for that sort of thing during wartime. Entire companies were created out of thin air for the purpose of deceiving the enemy. In this case, if in some future time the truth came out the defense that it was pursuant to a federal court order would be a legitimate defense. And since no liability could accrue and no financial loss to investors could be shown there would be no effect on share prices IMHO.
Folks have been doing this lately, and now it's a 'movement'. I suspect it is all in vain. It seems to me that the secret court would simply interpret removing the tag as informing de facto, and requiring you to leave the tag in place even though it is no longer true. So I think it's a pointless gesture at best, and most likely a deceptive error that is possibly worse, since folks might depend on its veracity / correctness.
And that is a valid concern. Most folks don't know that the word 'Aspirin' was originally a trademark of Bayer. In the 1930s the courts said that Bayer hadn't sufficiently defended the term against generic use, and ruled it was no longer a trademark in the US. But for a long time (still?) it was still a valid trademark in Canada. And Xerox Corp. spent $millions defending the word xerox as a term for photocopying. This is kinda the converse of 'use it or lose it': 'make sure nobody else uses it _except to describe your product specifically_, or lose it'.
Long ago there was an Apple Music store in San Luis Obispo CA, complete with an apple logo. I DK if it's still there. I suspect it predated Apple Corps.
Actually the parent is not quite right. Wikipedia has a good summary. The first litigation began in 1978, when Apple Corps. sued Apple over the trademark. This was long before iTunes. The 1981 settlement involved a payment (later found to be $80,000) to Apple Corps by Apple Computer, Apple Computer agreed not to get into the music business and Apple Corps agreed not to get into the computer business.
This led to a series of additional litigation when Apple Computers began to support music and later video publishing with a synth card in the Apple IIGS (effectively ending that product's lifecycle). And again when Apple included a sampled system sound in the OS, and a couple more times over various ways to distinguish what the two companies do, and most recently when the iTunes project reared its head.
Some of these suits were settled, others went to trial. To at least some extent it is necessary - boundaries sometimes need to be set. Ideally this would be done by negotiation, arbitration, and litigation in that order. IMHO this process is just a way of establishing boundaries and testing the other party's willingness to defend their turf. It is just like kids in the playground establishing which part is 'owned' by which clique, and similar to what nations do - today the Russians are flying bombers over the border between Sweden and Russia, basically testing Sweden's resolve and response time. The Russians/Soviets and the US have done that with each other for years. And the US Navy regularly sails their ships through areas like the China Sea, maintaining the 'right of innocent passage' in territorial waters.
No, I take it back. MVS is definitely scanning the lasers. The output of the three laser diodes is modulated, then merged into one beam, then run through the MEMS scanner. So the beam is scanned across the retina.
Followup: from This it appears that MVS is now (always was?) using a MEMS scanner - basically a DLP. So I think I'll stand corrected.:) But this also makes me wonder if the topic of this thread is going to have to deal with the MVS patent portfolio.
My brother worked for MicroVision Systems back in the 1990s - I'm almost certain they were scanning one (monochrome) or three (RGB) laser diodes. These were for head-up displays on some military flight hardware - $400K each. I think DLPs were not technically capable at that time. The product was based on work done at U Washington (IIRC) in the late 1980s, about the same time as DLPs were being developed. I'm too lazy to find out what they were using back then though, so I could be way off.
Not to mention those ubiquitous four-wheeled vehicles that burn extremely flammable and poisonous petrochemicals, and move at speeds several times as fast as the fastest animal alive - and are built using materials refined in mile-long fiery furnaces or cooked out of more petrochemicals! Did you know that the of intelligence to momentum of that vehicle plus its herder is lower than almost any animal?
When these vehicles were first introduced, laws in some places required they be preceded by a person carrying a flag, to warn oncoming horse and buggy traffic of the fire-snorting beast. Perhaps we should have kept that law in place!
A system much like this has been in use in military applications since the mid-1990s - see Micro Vision Systems. I don't recall if they use micromirrors but I think not.
There are laser systems out there (AFAIK only for military applications) - see Microvision Systems. I don't think they use micromirrors, rather they use a single scanning mirror, but I don't know for sure. I'm not sure how the micromirrors are used - is each one fixed, and the laser scanning across? That's basically a fancy Fresnel lens. Or is each micromirror used as a shutter, analogous to the LightValve projectors? In that case the laser output is first expanded via a lens, so the maximum product of light * time is fixed and there are no high density time-dependent pulse as below.
Using a point-output laser and a scanning mirror (analogous to how a laser printer works), I think there may still be a potential problem. If scanning a laser across your retina, an individual retina cell only receives light for a tiny fraction of the frame time - say 1/960000 of the total frame time for 1200x800 pixels. So the brightness has to be high enough to provide a sufficient amount of energy for that cell to perceive the proper level of illumination. If the laser were to stop moving, then that same brightness might be hundreds or thousands of times too bright for continuous (even for one full frame time) use, and could cause damage.
By way of analogy, if the sun suddenly comes out from behind a tree or cloud, your eye reflexively closes the iris, and you reflexively close your eye and/or turn away. The short duration of that brightness doesn't cause significant damage. But if you continue to look at the sun and don't close your eye or turn away, you'll fry your retina.
Slashdot Mirror
Yes indeed, I've read some of his stuff - highly amusing! :)
LFTRs mean the death knell of the fuel rod manufacturing and delivery industry - costing Westinghouse and GE zillions of dollars in revenue. Hmmm.
From what I've read, the salts in use are not corrosive. Proliferation risk is on the order of 1% as high as light water reactors. I would argue that the reason chemical plants are more accident prone is that there is less care being taken. On site processing of the liquid is considered much more straightforward and easier than what is presently required at light water plants.
A major advantage of LFTRs, and (I speculate) a major reason why the commercial companies haven't pursued them to date is that Westinghouse and GE nuclear divisions' major revenues are from manufacturing and reprocessing the very expensive fuel rods. That business goes away when the raw material is essentially a simple commodity. LFTRs could be the death knell of the nuclear fuel business. LFTRs are expected to be able to 'burn up' all of the existing high level nuclear waste, fissionable material in spent fuel rods, etc. - greatly reducing the present problem with spent fuel rods getting stacked at every power plant now. Would we still need Yucca Flat? Open question.
Considering that freight cars of red fuming nitric acid and other much more nasty chemicals are routinely shipped around the country and the world in train car loads on a daily basis, I don't think the chemistry in the LFTRs is at all a signficant issue - and the LFTR runs at under 100 PSI.
I don't recall if the LFTR liquid is solid at room temp. I did read that pure Thorium tetrafluoride melts at 1100C, but the liquid is not pure ThFl4.
My recollection from quite a bit of reading in this area was that the new head of AEC whose name I forget, besides actually disliking the guy running the MSR experiment, also did not like the fact that the MSR did not produce enough bomb material, while the liquid metal fast breeder reactor (LMFBR) did. They had a budget cut (Nixon) and decided to put all the money into the LMFBR. Disagreements ensued and the MSR guy was actually fired by AEC. The LFTR is projected to produce less than 1% as much highly radioactive waste, and is generally considered a useful system for burning up all that stuff and getting rid of it.
I believe that theoretically an LFTR could run as high as 1500C, but there are limitations due to having to actually build something that could withstand that temperature. Pure thorium tetrafluoride melts at 1100C and boils at 1600C (according to wikipedia, of course).
The fuel expands as it gets hot, reducing the density and fission rate - it's self moderating, and without a continued source of trigger neutrons the reaction automatically damps out.
Nice thing about Thorium is it essentially doesn't do that. There's a bit of that going on inside the reactor but it's self-damping. Thorium by itself is very faintly radioactive, releasing alpha particles. The LFTR creates less than 1% as much waste as a light water reactor - or at least according to theory. See this article for more info on advantages and disadvantages.
The nice thing about the LFTR is that the system is under only about 15-50 PSI pressure (same as household water systems), the Thorium is not very radioactive (by itself it just puts out alpha particles, but there is harder stuff going on inside), the molten salt formula can be relatively stable (although the most common plan at present does include Beryllium which is nasty stuff). the reaction doesn't generate explosive gases, and the reaction stops on its own when you remove the power. So the accident potential is a couple orders of magnitude smaller than the classic light water fission reactors. This article covers most of the topics, and has links to several more.
Another nice thing - Thorium is essentially 100% fuel, where Uranium is naturally only about 1% fuel and has to be enriched by an expensive and dangerous process, such as the gas centrifuges being used by Iran. So it's said that 500 tons of Thorium could provide all of the US electrical needs for a year, and the US has 64000 tons of known reserves - that would be 128 years worth of fuel. (Thorium is, in fact, a rather problematical waste product from mining and refining rare earth elements, with which it's often found.)
Actually there's a fairly simple fusion reactor that you can build on your tabletop. It even works, but it doesn't produce more energy than it consumes. The Philo T. Farnsworth mentioned is also regarded as the best candidate as the original inventor of TV. The Wikipedia article also has links to some other methods.
Approximate quote from a guy whose name I forget, at Siggraph 1980. He was at JPL at the time, later went to work at the newly-formed Pixar (or was it Industrial Light and Magic? I forget), got bored and went back to JPL. He was the first person I know of to create and demonstrate what he called 'inbetweening', now called morphing, used in various JPL CG videos: "Computer graphics, the industry where the technology gets better while the hair gets shorter."
That was the same period when the Harvard computer graphics gurus could be depended on to be wearing three-piece suits and tennis shoes. And one of the hottest geeks at Tektronix was believed to essentially never wash his t-shirt - singular! He was on the international Pascal standards committee, IIRC.
I might also include the remark from Richard Stallmann, about how in the 1960s at MIT there were a dozen or two computer science students, of which 10 were really good; and years later there were a couple hundred computer science students, of which about 10 were really good.
Neither of these is an exact quote; hopefully the gist survives.
I'm reminded of my high school chemistry class. One whole side of the classroom was glass with floor to ceiling drapes, which were peppered from top to bottom and the full length with tiny little holes from some experiment that didn't go according to plan. Wish I had been there! :D
Indeed. Try to find a chemistry set that contains potassium permanganate and glycerin these days, much less the ingredients for gunpowder.
We had science fair experiments in sixth grade that today would get you into the newspapers and black SUVs showing up. And going back before my time, my somewhat older neighbor built a pipe cannon back in the 1940s that fired rocks over a mile.
But there's always the Internet, where you can find the free e-book "Ignition" by John Clark. Very funny history of liquid rocket propellants from the 1940s through to the early 1970s. Any discipline where red fuming nitric acid is considered one of the more stable, tractable ingredients is going to be interesting. (compare with Chlorine Trifluoride)
Much like reading your posts, along with that pathetic signature of yours
Actually the sig does have an arguable point. There is a substantial, and I would say, growing minority, mostly libertarians, who think that Lincoln was not the grand hero that we are taught in school. For starters, he suspended Habeus Corpus, despite believing he had no legal right to do so. It is apparent that he himself believed that the states had a right to secede. And various of his acts were the first step toward the diminution of the importance and sovereignty of the individual states, including instituting the first federal income tax. Others than myself could argue this point, I'm really not up on the details.
I don't agree with that position. For myself, I feel that, like all humans, Lincoln had his good and bad aspects. I do regret that this was the period when the Northern banking and financial establishment essentially took control of the direction of the nation. While it was being misused at the time, the concept of States' Rights is an important one, that has been continuously whittled away until today when the Commerce Clause is used to basically get federal priority over everything including what crops I can grow or not grow (if I had a farm) and whether I wear a seatbelt and how fast I can drive.
There is yet another point of view. I once read a book called "The Lincoln Conspiracy", which asserted that the assassination (originally planned as a kidnap and impeachment) was planned by a cabal lead by Edwin M. Stanton to prevent what they saw as overly liberal plans for the reconstruction period. This is probably closer to fiction than fact, but it was fascinating to read.
There are numerous historical precedents for that sort of thing during wartime. Entire companies were created out of thin air for the purpose of deceiving the enemy. In this case, if in some future time the truth came out the defense that it was pursuant to a federal court order would be a legitimate defense. And since no liability could accrue and no financial loss to investors could be shown there would be no effect on share prices IMHO.
Folks have been doing this lately, and now it's a 'movement'. I suspect it is all in vain. It seems to me that the secret court would simply interpret removing the tag as informing de facto, and requiring you to leave the tag in place even though it is no longer true. So I think it's a pointless gesture at best, and most likely a deceptive error that is possibly worse, since folks might depend on its veracity / correctness.
And that is a valid concern. Most folks don't know that the word 'Aspirin' was originally a trademark of Bayer. In the 1930s the courts said that Bayer hadn't sufficiently defended the term against generic use, and ruled it was no longer a trademark in the US. But for a long time (still?) it was still a valid trademark in Canada. And Xerox Corp. spent $millions defending the word xerox as a term for photocopying. This is kinda the converse of 'use it or lose it': 'make sure nobody else uses it _except to describe your product specifically_, or lose it'.
Long ago there was an Apple Music store in San Luis Obispo CA, complete with an apple logo. I DK if it's still there. I suspect it predated Apple Corps.
Actually the parent is not quite right. Wikipedia has a good summary. The first litigation began in 1978, when Apple Corps. sued Apple over the trademark. This was long before iTunes. The 1981 settlement involved a payment (later found to be $80,000) to Apple Corps by Apple Computer, Apple Computer agreed not to get into the music business and Apple Corps agreed not to get into the computer business.
This led to a series of additional litigation when Apple Computers began to support music and later video publishing with a synth card in the Apple IIGS (effectively ending that product's lifecycle). And again when Apple included a sampled system sound in the OS, and a couple more times over various ways to distinguish what the two companies do, and most recently when the iTunes project reared its head.
Some of these suits were settled, others went to trial. To at least some extent it is necessary - boundaries sometimes need to be set. Ideally this would be done by negotiation, arbitration, and litigation in that order. IMHO this process is just a way of establishing boundaries and testing the other party's willingness to defend their turf. It is just like kids in the playground establishing which part is 'owned' by which clique, and similar to what nations do - today the Russians are flying bombers over the border between Sweden and Russia, basically testing Sweden's resolve and response time. The Russians/Soviets and the US have done that with each other for years. And the US Navy regularly sails their ships through areas like the China Sea, maintaining the 'right of innocent passage' in territorial waters.
No, I take it back. MVS is definitely scanning the lasers. The output of the three laser diodes is modulated, then merged into one beam, then run through the MEMS scanner. So the beam is scanned across the retina.
Followup: from This it appears that MVS is now (always was?) using a MEMS scanner - basically a DLP. So I think I'll stand corrected. :) But this also makes me wonder if the topic of this thread is going to have to deal with the MVS patent portfolio.
My brother worked for MicroVision Systems back in the 1990s - I'm almost certain they were scanning one (monochrome) or three (RGB) laser diodes. These were for head-up displays on some military flight hardware - $400K each. I think DLPs were not technically capable at that time. The product was based on work done at U Washington (IIRC) in the late 1980s, about the same time as DLPs were being developed. I'm too lazy to find out what they were using back then though, so I could be way off.
That problem is mentioned in TFA, so you are right on.
Not to mention those ubiquitous four-wheeled vehicles that burn extremely flammable and poisonous petrochemicals, and move at speeds several times as fast as the fastest animal alive - and are built using materials refined in mile-long fiery furnaces or cooked out of more petrochemicals! Did you know that the of intelligence to momentum of that vehicle plus its herder is lower than almost any animal?
When these vehicles were first introduced, laws in some places required they be preceded by a person carrying a flag, to warn oncoming horse and buggy traffic of the fire-snorting beast. Perhaps we should have kept that law in place!
A system much like this has been in use in military applications since the mid-1990s - see Micro Vision Systems. I don't recall if they use micromirrors but I think not.
There are laser systems out there (AFAIK only for military applications) - see Microvision Systems. I don't think they use micromirrors, rather they use a single scanning mirror, but I don't know for sure. I'm not sure how the micromirrors are used - is each one fixed, and the laser scanning across? That's basically a fancy Fresnel lens. Or is each micromirror used as a shutter, analogous to the LightValve projectors? In that case the laser output is first expanded via a lens, so the maximum product of light * time is fixed and there are no high density time-dependent pulse as below.
Using a point-output laser and a scanning mirror (analogous to how a laser printer works), I think there may still be a potential problem. If scanning a laser across your retina, an individual retina cell only receives light for a tiny fraction of the frame time - say 1/960000 of the total frame time for 1200x800 pixels. So the brightness has to be high enough to provide a sufficient amount of energy for that cell to perceive the proper level of illumination. If the laser were to stop moving, then that same brightness might be hundreds or thousands of times too bright for continuous (even for one full frame time) use, and could cause damage.
By way of analogy, if the sun suddenly comes out from behind a tree or cloud, your eye reflexively closes the iris, and you reflexively close your eye and/or turn away. The short duration of that brightness doesn't cause significant damage. But if you continue to look at the sun and don't close your eye or turn away, you'll fry your retina.