Do you have any idea how long a few thousand years is?
The oldest pyramids are what, ~4000 years old? Those are primitive human structures. Some cave paintings are several times as old and still holding up.
If we are trying to get rid of a bunch of nasty isotopes with half-lives up to 30 years (strontium 90), putting them away for a mere thousand years reduces them to about one ten-billionth of their original abundance. 3000 years is both overkill and not very difficult.
Batteries do not come close nor does anything else that I remember hearing about.
Batteries with the requisite performance are already here, and there is already a car running on them. I've been unable to find out exactly how much production we have at the moment, but at the standard 20% price cut for every 2x increase in cumulative production it looks like the adoption of batteries for cars could be the thing that makes them economical.
practical tests have shown that reactor grade plutonium, with all its isotopes, can be still be used to make one. It will be dirty, it will have a lower yield, it will use more plutonium, it will still explode.
You've got three misconceptions going there.
The spontaneous fission rate listed for PWR plutonium by your first reference is more than twelve times as high as weapons-grade. This makes the requirements for the implosion mechanism more than 100 times as steep (12 times the implosion velocity means 144 times the kinetic energy).
It's actually worse than that. The isotope abundances listed by your reference reflect a slightly lower burnup than the 33,000 megawatt-days/ton listed for mine. I understand that current PWR practice is to use a burnup of 50,000 MW-d/t or more, which would make the isotope composition even worse for the hypothetical proliferator.
There's more to a bomb than just the fission elements. The implosion mechanism has to work correctly and not pre-trigger, and the more heat and radiation emitted by the "pit" the more stress it's going to put on the explosive mechanism. Your bomb is not going to work if the explosive lenses have turned to jelly, and it's going to be mighty hard to hide a bomb if it requires a huge cooling system to avoid melting itself.
Those factors make it so difficult to make bombs out of recovered PWR plutonium that not one proliferator, not India or Pakistan or Iraq or Iran or North Korea, has even tried to make a bomb that way. Not even one; they all used small research reactors designed for (surprise!) irradiating materials for testing or making specialty isotopes (Co-60 for medicine counts, but Pu-239 is just another "speciality product"). The Russians designed the RMBK reactors for continuous refuelling so that they could make weapons materials; PWRs have no such features.
Add to this the niggling detail that we are talking about a US nuclear program, we'd be keeping the stuff within our borders, and the US could easily add a bit of some nasty isotope to any recovered fissonables to make diversion both difficult to do and easy to detect. That makes it a non-issue.
you could (with some slight of hand) swap some unspent pellets for spent pellets, and process the spent pellets yourself for plutonium.
Ah, yes. You're going to take a spent PWR fuel rod bundle, with the fuel pellets swelled from crystal damage and the expansion of the fission products, un-weld the zirconium cladding, substitute fake pellets (which will not have any of the radioisotopes characteristic of the pellets removed), and weld them up again. You're going to do this to enough rods (in what hot cell?) to steal the materials for at least one, and preferably several, bombs. And nobody's going to notice the disturbance in the cladding, the difference in isotope loading, or any of the other details that you'd alter in the process?
If that's so easy, why has every proliferator thus far taken another route?
Separating plutonium from uranium is a reasonably easy chemical process.
Separating the problematic (238, 240, 241) isotopes of plutonium from Pu-239 is not a chemical process. Not only is there about 1/3 of the mass difference between the isotopes as between U-235 and U-238, but you need to strip both the lighter and heavier isotopes from the desired one.
Bomb makers get rid of this problem by very short irradiation of a depleted uranium element; if the Pu-239 is not allowed to build up it cannot be transmuted. On the other hand, building up fuel is the purpose of a power-producing breeder reactor.
An excellent summary with a table of typical isotopic compositions for weapons-grade Pu and spent reactor fuel is here. It was the first hit I got with the search string "PWR fuel plutonium isotopes" in Google; what's your excuse?
Breeder reactors produce an abundance of weapons-grade materials.
A common lie of anti-nuke activists. Weapons-grade uranium is concentrated to over 70% U-235, and weapons-grade plutonium is > 93% Pu-239. PWR-grade uranium is about 3% U-235, and neutron capture in breeders contaminates the plutonium with much more than 7% of Pu-238, Pu-240 and Pu-241. You can't make a bomb out of 3% U-235 (it cannot go prompt-supercritical because it needs a moderator) and the high spontaneous-fission rate of the higher isotopes of plutonium makes it impractical to make bombs from them (too much heat generation, little chance of the implosion system getting its job done before the chain reaction starts and takes the mass sub-critical again).
"How much energy is required to replace our fossil fuel consumption?
Depends on the definition of "fossil fuel consumption". It would take around 200 GW plus losses to replace the US consumption of petroleum-based motor fuel, according to my analysis. (Yes, I know, the EIA has broken the important links. Worse, they've split the data which used to be on one page over several.)
What are the initial costs of the program, and just how cheap could the electricity be?
The problem comes in two parts, generating the power from nuclear and then transforming it to something which can be put aboard a vehicle. As a quick BOTE calculation, if you need 250 GW of generation at $1110/KW, that's $275 billion dollars. The most efficient way of getting it aboard vehicles is to use batteries. Add 20 KWH of batteries for 100 million vehicles at $100/KWH and I get an additional $200 billion. Over ten years that would be about $50 billion per year.
How expensive would it be for our industries to convert?
Industries which need oil as a chemical feedstock would be largely impractical to convert to non-fossil, though non-petroleum is much easier. Industries which simply consume electricity would require no conversion. Industries which use process heat would pay a lot more if they used electricity instead, or perhaps less if they were close to a nuclear plant and could get spent steam.
How expensive for home and auto conversions?
It's not going to be practical to convert most cars; they will be replaced. Neither are you going to convert a home to nuclear. Converting to electric is cheap, converting natural gas appliances to hydrogen would also be cheap if it could be made safe enough (which I doubt). Cost of energy would be much higher; it would be cheaper to re-insulate, change building codes and use e.g. solar water heaters.
How much of this cost should be picked up by the government?
Do you mean paid out of increased taxes or added to the deficit? (The question betrays stupidity.)
Bottom line: is nuclear power cheaper than our current oil-driven middle-east policy, with all of its blowback?
When we could do it for $100 billion/year or less over 10 years? Absolutely.
Your questions are easy. We could easily set up a bunch of thorium-breeder reactors and start them with our surplus fissionables from decommissioned nuclear weapons, and the fission products (the real "nuclear waste") needs to be isolated for only a few thousand years, save for a few troublesome isotopes. It's not our chemists and engineers who have trouble with this, it's the politicians and activists.
That's fine if you intend to live, work, grow your crops etc. in a cave (and your water supply is still going to be affected by rainfall). I don't think that this describes too many people.
If you go searching for data on borehole temperature measurements, you'll find that annual temperature cycles are measurable for some years as they propagate into the earth. It's true to a degree that "the temperature is always the same underground", but only to a degree; think about what "frost line" means for an example.
So... we'll schedule the Global Cooling panic for what, 2030-ish? That good for everyone?
By that time we ought to be able to control the radiative balance to our specifications... if we get started now. We can't be certain that the solar "constant" (there's a misnomer) is going to decrease as projected, so we may still have to take measures to deal with destructive levels of warming.
Save your Global Cooling books from the 70s, they'll be invaluable in showing how long it has been a problem even as the Global Warming hysteria is quietly, but thoroughly, whitewashed out of existance (just as the Global Cooling panic has been, as of today).
We still don't know why we're apparently late for the next glacial period, and the answer could surprise us. If the old cooling books turn out to be right, it will probably be for all the wrong reasons. This means that authors will still have employment prospects in the field.;)
(PS: I would expect the Earth's temp, if it is affected significantly by the Sun, to lag behind it by several years, because it has one hell of a lot of "thermal inertia".)
If you expect that, how do you reconcile it with the rapid changes in temperature due to sunlight variations from Earth's axial tilt? The oceans may take years to adjust fully but we'd feel the effects much more quickly on land.
The Sun is approximately 4.5 billion years old. An increase in the average brightness of 30% over that time is equal to 6.7% per billion years, or.00000067% per century. If you think that this will become a measurable change in the next century, you obviously never learned anything worthwhile from a lab course (and nobody should trust you with numerical methods, either).
even in cernobyl, there was 'only' chemical explosion (spreading radioactive material)
Actually, Chernobyl was a steam explosion driven by the heat from the runaway fission reaction; there was no chemical contribution to the initial incident (though the "radioactive charcoal grill" which ensued did involve chemical reactions).
Expanding on what hawkeye said, concerns about radiation in the atmosphere are ameliorated by not starting the reactor until you're out of the atmosphere. All you need is a chemical first-stage booster for this, to throw to 40 miles or so (not even as high as Space Ship One). If the booster cuts out too soon or the reactor fails to start, you could always break it into sub-critical pieces or scram the control rods (preferably designed so that they're swaged into place if the assemblage is deformed significantly).
... would you have enough thrust in the lower gravity of Mars to lift off again with a full payload, say, of people and Mars rocks?
Bob Zubrin (yes, the Mars Society guy) proposed a rocket to do just that. It was called NIMF (Nuclear rocket using Indigenous Martian Fuel) and would have used liquid CO2 as the propellant. I have a copy of his paper somewhere. I could not find the original paper on-line but you will find multiple references to it with a Google search.
The two RTGs in the Apollo 13 LEM appear to have gone into the Pacific ocean. No radiation was detected from them; the Pu-238 oxide ceramic was wrapped in multiple layers of material which would have had to burn off before it could be affected, and the ceramic itself would go straight to the bottom of the ocean.
Once it got there it wouldn't hang around long; Pu-238 decays into U-234 with a half-life of less than a century. Ten thousand years would see it gone.
The misconceptions in the parent are legion, and I can only address a few.
... you'd need two sub-critial lumps separated enough so the radiation engendered by their proximity wouldn't simply vaporize the engine before a chain reaction could take off.
Bombs typically use spherical shells, not separate lumps. To be critical, each splitting atom has to emit neutrons which have a probability of splitting ~=1 other atoms. To be prompt supercritical requires the prompt neutrons to have probability of splitting >1 other atoms (there are also delayed neutrons from the fission products; if I understand correctly, these usually take too long to be significant in a bomb explosion). It doesn't matter how you arrange the fissionables so that they're sub-critical until you want them otherwise, anything will do.
The two-sub-critical masses have to be brought into close proximity quickly
Which depends on the spontaneous fission rate of the material you're using. U-235 is low enough that you can just fire a slug into a sub-critical tube and it's very likely that nothing will happen until after they've finished coming together (half-life of 700 million years means low fission rate). Pu-239 requires a rapid spherical implosion (24,000 year half-life) and higher isotopes of Pu will drive the requirements even harder (or cut the likelihood of a successful "boom" even lower).
It's pretty safe to say that the likelihood of a nuclear reactor crushing into a critical configuration despite the normal measures taken to keep it "off" (neutron-absorbing control rods inserted, etc) is vanishingly small. In that you are correct.
You'd fire both shotgun shells down the tube to meet each other.
In a gun design you only need to move one mass. This only appears to be feasible with U-235.
The temperature and the radiation caused by their increasing proximity tries to vaporize the assemblage
Faulty thinking; the temperature and radiation (which turns the bomb core into high-pressure gas and pushes it apart again) are caused by the reaction; they are not separate from it.
One point you appear to be missing is that the nuclear reaction takes a certain amount of time; neutrons are not infinitely fast, nuclei do not fission instantaneously, the exponential change rate of the reaction (whether growth or decay) is controlled by the composition of the material and its geometry. The geometry controls whether a splitting atom has a > 1 or < 1 probability of causing another fission. If the probability is >>1, you've got an explosion in progress; if it is <.5, you've got a lump.
The goal of the bomb designer is to turn the sub-critical mass into a prompt-supercritical mass before a chain reaction can begin and take the mass apart again; to this end they design implosion mechanisms and neutron generators to make everything happen when desired and not a microsecond before.
The goal of the reactor designer is to make certain that the chain reaction is always under control. We can see that this isn't overly difficult; even Three Mile Island had a nicely-controlled reaction (its problem was lack of coolant), and only the Russians appear to have been careless enough to have a major incident (and without any containment building either, tsk tsk).
How does the reader know that without going back to primary sources? Cite the primary sources instead. Wikipedia is good for illustrating general concepts but not as a reliable source.
The poster even misquoted his own cite, implying that microturbine systems can reach 90% efficiency despite the fact that "combined heat and power" is completely irrelevant to a system for powering a computer. He appears to make a habit of such things.
Gas turbines are inefficient by design[1], because they use combustion to produce power[2], and the combustion process is inherently inefficient from an energy transfer point-of-view.[3]
No they aren't. Gas turbines can be considerably more efficient than steam turbines, because they aren't subject to the temperature limits of a system which has to work with steam (steam pressures go through the roof and steam itself becomes corrosive). Higher temperatures mean greater efficiency.
Combustion engines can be quite efficient. Large gas turbines and over-the-road (high speed) diesel engines can hit 40%. Low-speed diesels can reach 50%.
Combustion implies an increase of entropy, but the rest of your statement makes no sense to me.
I'm an environmental econ major
I'm an electrical engineer with a lot of side study in other areas. If you want to argue thermodynamics with the numbers and equations, bring it on. One of us cannot help but become enlightened.
The size doesn't matter...
What makes you say this? Losses affect efficiency, and size affects many things which influence losses. Heat transfer and viscous friction are two things which decrease in importance as size increases.
The only way to make gas turbines more efficient is to pump the excess heat from the exhaust into a steam turbine and gain a bit more bang for your buck...
Any kind of vapor turbine would do. So would a Stirling engine, Ericcson-cycle engine, or Peltier junction system (these would require larger radiators with much more cooling air than the turbine itself would... though you'd probably need a heat diffuser for the turbine just to keep case temperatures safe). The generic term for the use of the exhaust heat from one engine to run another is a "bottoming cycle".
I mostly agree with you on your last statement, though I question whether this microturbine represents any kind of breakthrough at all. I just don't see what kind of application is served by a high power-density, high energy-density, low-efficiency, high-temperature device; most of the cybernetic applications appear to be incompatible with characteristics like the heat output. This is not to say that there are not applications out there, they just don't seem to be any of the familiar ones.
The microturbines the authors appear to be talking about are in the neighborhood of 30 kilowatts and bigger, not 15 watts. A non-micro turbine would have an output of megawatts; some are capable of hundreds of megawatts.
Neither "reference" (they aren't worthy of the term) mentions a thing about efficiency.
This matters a lot, because small turbines suffer much more from viscous flow losses and heat-transfer losses than large ones. If a 50 W microturbine is 10% efficient, its waste heat will amount to 450 watts; if it is 5% efficient, the waste heat will be 950 watts! This could easily lead to them being banned from commercial aircraft, because the extra heat load and oxygen consumption would drive A/C loading too high (not to mention the discomfort of adjacent passengers).
The US could do the same as the EU, and prohibit export of personal data to jurisdictions which do not have equal or better privacy protections as ours. That would stop a lot of outsourcing in general, and probably be a vote-winner among unemployed geeks.
A government which is abiding by the law would be firing and prosecuting the Secret Service agents and police officials responsible for these outrages, rather than institutionalizing the violation of civil rights under color of law. A government which abuses the power of arrest to "protect" the President from seeing people who disagree with his policies is not a government which is abiding by the Constitution, and to allow it to remain in office one day longer is to place all rights in jeopardy. The bastard has violated his oath of office (so much for his claim of "keeping his word"), and voting him out is the duty of everyone who holds the Constitution to heart.
Which, unfortunately, isn't all that many people these days.
Actually, there are large differences with prior "crowd dispersal" techniques. The police in recent times have invested lots of money and time into 'less than leathal' weapons for dealing with crowds.
... which makes it that much easier for the government to use them to squelch political discourse and peaceful (if noisy) protest, because the consequences are so much less likely to create martyrs (tin soldiers and Nixon coming, anyone?). Notice how much anti-speech action we're seeing?
And what's with the epithet? I never even met Kenny!
I did miss the 60's, but the tactics detailed in TFA remind me of the firehoses used against the civil rights activists in the old South or King Dailey I's police abuses at the Chicago Democratic Convention of 1968. Our government has already gone too far in that direction.
Which is not to praise the Weathermen or any of the leftist nutcases of the time, but I'm talking about what the people in the government do with the power they're supposed to be using on my behalf.
I remember speeches by pols where protest signs held up in the auditorium were taken in stride. Hell, I attended a speech by President Ford which was punctuated by cries of "What about Nixon?" from somewhere off to my right. (This was before I was able to vote, natch.)
I have never, ever seen anything like the reflexive hostility of this administration to normal political opposition. This Bush should expect it; he got into office on a hugely controversial court decision and with fewer votes than his opponent, and has proceeded to embark on an extreme right-wing program targetting access to and even information about birth control, gutting of pollution regulations and the doctoring of scientific information on government websites to conform to a partisan agenda.
Nothing can excuse this. Nothing. And then we read about the arrest and harassment of people whose only act is to register their discontent with the acts of the President, over and over and over.
I have few beefs with the President over the most controversial of his actions, over in a hot, tired and dusty land far away... but the rest of this stuff threatens the very soul of America if it is allowed to continue. So the only thing I can do is to vote the rascal out, as a lesson to him and any who would follow him:
Thou shalt not abridge the freedom of speech, or of the press, or tell falsehoods about the conclusions which our taxpayer-financed research has given us, or let anyone contaminate my air and water for the bonuses of the corporate executive class. Not In My Name.
(And that goes for anyone pandering to the postmodern PC idiotarians on the other side too; throw sops to them, and you've declared yourself my enemy.)
Sex-changing in fish is sufficiently unusual that discoveries of species which do it make the scientific literature. If it was normal in bass, we'd certainly have learned about it long before now.
In this case, it's much worse than that. The fish's testicular tissue is claimed to have produced eggs, but you might notice that the article didn't mention anything about the morphological changes required to become a functioning female. If you began producing ova in your nuts would that make you female in any meaningful sense of the word, or just ill?
This phenomenon needs to be analyzed, the cause identified and stopped. If we don't do this, we're going to lose things starting with the fish, and continuing up to ourselves - and if this doesn't worry you, spend some time looking up the literature on hormone mimics, phthalate and the other disturbing stuff that gets to us in eerie ways like leaching out of baby bottles.
What I was trying to suggest regarding the parent comment If you have any process which can generate enough hydrogen cheaply enough... is that if we had such a process we could use the hydrogen directly in the generator.
Ah. The meaning I had in mind was that you could use hydrogen to capture CO2 (from whatever source) and convert it to a form which would allow its indefinite storage. Heavy waxes allow storage over geologic time; for examples, look at Venezuela's "oil" fields, oil shale and Canada's tar sands.
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If we are trying to get rid of a bunch of nasty isotopes with half-lives up to 30 years (strontium 90), putting them away for a mere thousand years reduces them to about one ten-billionth of their original abundance. 3000 years is both overkill and not very difficult.
- The spontaneous fission rate listed for PWR plutonium by your first reference is more than twelve times as high as weapons-grade. This makes the requirements for the implosion mechanism more than 100 times as steep (12 times the implosion velocity means 144 times the kinetic energy).
- It's actually worse than that. The isotope abundances listed by your reference reflect a slightly lower burnup than the 33,000 megawatt-days/ton listed for mine. I understand that current PWR practice is to use a burnup of 50,000 MW-d/t or more, which would make the isotope composition even worse for the hypothetical proliferator.
- There's more to a bomb than just the fission elements. The implosion mechanism has to work correctly and not pre-trigger, and the more heat and radiation emitted by the "pit" the more stress it's going to put on the explosive mechanism. Your bomb is not going to work if the explosive lenses have turned to jelly, and it's going to be mighty hard to hide a bomb if it requires a huge cooling system to avoid melting itself.
Those factors make it so difficult to make bombs out of recovered PWR plutonium that not one proliferator, not India or Pakistan or Iraq or Iran or North Korea, has even tried to make a bomb that way. Not even one; they all used small research reactors designed for (surprise!) irradiating materials for testing or making specialty isotopes (Co-60 for medicine counts, but Pu-239 is just another "speciality product"). The Russians designed the RMBK reactors for continuous refuelling so that they could make weapons materials; PWRs have no such features.Add to this the niggling detail that we are talking about a US nuclear program, we'd be keeping the stuff within our borders, and the US could easily add a bit of some nasty isotope to any recovered fissonables to make diversion both difficult to do and easy to detect. That makes it a non-issue.
Ah, yes. You're going to take a spent PWR fuel rod bundle, with the fuel pellets swelled from crystal damage and the expansion of the fission products, un-weld the zirconium cladding, substitute fake pellets (which will not have any of the radioisotopes characteristic of the pellets removed), and weld them up again. You're going to do this to enough rods (in what hot cell?) to steal the materials for at least one, and preferably several, bombs. And nobody's going to notice the disturbance in the cladding, the difference in isotope loading, or any of the other details that you'd alter in the process?If that's so easy, why has every proliferator thus far taken another route?
Bomb makers get rid of this problem by very short irradiation of a depleted uranium element; if the Pu-239 is not allowed to build up it cannot be transmuted. On the other hand, building up fuel is the purpose of a power-producing breeder reactor.
An excellent summary with a table of typical isotopic compositions for weapons-grade Pu and spent reactor fuel is here. It was the first hit I got with the search string "PWR fuel plutonium isotopes" in Google; what's your excuse?
- "How much energy is required to replace our fossil fuel consumption?
- Depends on the definition of "fossil fuel consumption". It would take around 200 GW plus losses to replace the US consumption of petroleum-based motor fuel, according to my analysis. (Yes, I know, the EIA has broken the important links. Worse, they've split the data which used to be on one page over several.)
- What are the initial costs of the program, and just how cheap could the electricity be?
- The problem comes in two parts, generating the power from nuclear and then transforming it to something which can be put aboard a vehicle. As a quick BOTE calculation, if you need 250 GW of generation at $1110/KW, that's $275 billion dollars. The most efficient way of getting it aboard vehicles is to use batteries. Add 20 KWH of batteries for 100 million vehicles at $100/KWH and I get an additional $200 billion. Over ten years that would be about $50 billion per year.
- How expensive would it be for our industries to convert?
- Industries which need oil as a chemical feedstock would be largely impractical to convert to non-fossil, though non-petroleum is much easier. Industries which simply consume electricity would require no conversion. Industries which use process heat would pay a lot more if they used electricity instead, or perhaps less if they were close to a nuclear plant and could get spent steam.
- How expensive for home and auto conversions?
- It's not going to be practical to convert most cars; they will be replaced. Neither are you going to convert a home to nuclear. Converting to electric is cheap, converting natural gas appliances to hydrogen would also be cheap if it could be made safe enough (which I doubt). Cost of energy would be much higher; it would be cheaper to re-insulate, change building codes and use e.g. solar water heaters.
- How much of this cost should be picked up by the government?
- Do you mean paid out of increased taxes or added to the deficit? (The question betrays stupidity.)
- Bottom line: is nuclear power cheaper than our current oil-driven middle-east policy, with all of its blowback?
- When we could do it for $100 billion/year or less over 10 years? Absolutely.
Your questions are easy. We could easily set up a bunch of thorium-breeder reactors and start them with our surplus fissionables from decommissioned nuclear weapons, and the fission products (the real "nuclear waste") needs to be isolated for only a few thousand years, save for a few troublesome isotopes. It's not our chemists and engineers who have trouble with this, it's the politicians and activists.If you go searching for data on borehole temperature measurements, you'll find that annual temperature cycles are measurable for some years as they propagate into the earth. It's true to a degree that "the temperature is always the same underground", but only to a degree; think about what "frost line" means for an example.
The Sun is approximately 4.5 billion years old. An increase in the average brightness of 30% over that time is equal to 6.7% per billion years, or .00000067% per century. If you think that this will become a measurable change in the next century, you obviously never learned anything worthwhile from a lab course (and nobody should trust you with numerical methods, either).
The temperature variations have been tracked over centuries using heat-flow measurements in boreholes.
Once it got there it wouldn't hang around long; Pu-238 decays into U-234 with a half-life of less than a century. Ten thousand years would see it gone.
It's pretty safe to say that the likelihood of a nuclear reactor crushing into a critical configuration despite the normal measures taken to keep it "off" (neutron-absorbing control rods inserted, etc) is vanishingly small. In that you are correct.
In a gun design you only need to move one mass. This only appears to be feasible with U-235. Faulty thinking; the temperature and radiation (which turns the bomb core into high-pressure gas and pushes it apart again) are caused by the reaction; they are not separate from it.One point you appear to be missing is that the nuclear reaction takes a certain amount of time; neutrons are not infinitely fast, nuclei do not fission instantaneously, the exponential change rate of the reaction (whether growth or decay) is controlled by the composition of the material and its geometry. The geometry controls whether a splitting atom has a > 1 or < 1 probability of causing another fission. If the probability is >>1, you've got an explosion in progress; if it is < .5, you've got a lump.
The goal of the bomb designer is to turn the sub-critical mass into a prompt-supercritical mass before a chain reaction can begin and take the mass apart again; to this end they design implosion mechanisms and neutron generators to make everything happen when desired and not a microsecond before. The goal of the reactor designer is to make certain that the chain reaction is always under control. We can see that this isn't overly difficult; even Three Mile Island had a nicely-controlled reaction (its problem was lack of coolant), and only the Russians appear to have been careless enough to have a major incident (and without any containment building either, tsk tsk).
"Water? Fish copulate in that stuff!"
The poster even misquoted his own cite, implying that microturbine systems can reach 90% efficiency despite the fact that "combined heat and power" is completely irrelevant to a system for powering a computer. He appears to make a habit of such things.
- No they aren't. Gas turbines can be considerably more efficient than steam turbines, because they aren't subject to the temperature limits of a system which has to work with steam (steam pressures go through the roof and steam itself becomes corrosive). Higher temperatures mean greater efficiency.
- Combustion engines can be quite efficient. Large gas turbines and over-the-road (high speed) diesel engines can hit 40%. Low-speed diesels can reach 50%.
- Combustion implies an increase of entropy, but the rest of your statement makes no sense to me.
I'm an electrical engineer with a lot of side study in other areas. If you want to argue thermodynamics with the numbers and equations, bring it on. One of us cannot help but become enlightened. What makes you say this? Losses affect efficiency, and size affects many things which influence losses. Heat transfer and viscous friction are two things which decrease in importance as size increases. Any kind of vapor turbine would do. So would a Stirling engine, Ericcson-cycle engine, or Peltier junction system (these would require larger radiators with much more cooling air than the turbine itself would... though you'd probably need a heat diffuser for the turbine just to keep case temperatures safe). The generic term for the use of the exhaust heat from one engine to run another is a "bottoming cycle".I mostly agree with you on your last statement, though I question whether this microturbine represents any kind of breakthrough at all. I just don't see what kind of application is served by a high power-density, high energy-density, low-efficiency, high-temperature device; most of the cybernetic applications appear to be incompatible with characteristics like the heat output. This is not to say that there are not applications out there, they just don't seem to be any of the familiar ones.
This matters a lot, because small turbines suffer much more from viscous flow losses and heat-transfer losses than large ones. If a 50 W microturbine is 10% efficient, its waste heat will amount to 450 watts; if it is 5% efficient, the waste heat will be 950 watts! This could easily lead to them being banned from commercial aircraft, because the extra heat load and oxygen consumption would drive A/C loading too high (not to mention the discomfort of adjacent passengers).
The US could do the same as the EU, and prohibit export of personal data to jurisdictions which do not have equal or better privacy protections as ours. That would stop a lot of outsourcing in general, and probably be a vote-winner among unemployed geeks.
A government which is abiding by the law would be firing and prosecuting the Secret Service agents and police officials responsible for these outrages, rather than institutionalizing the violation of civil rights under color of law. A government which abuses the power of arrest to "protect" the President from seeing people who disagree with his policies is not a government which is abiding by the Constitution, and to allow it to remain in office one day longer is to place all rights in jeopardy. The bastard has violated his oath of office (so much for his claim of "keeping his word"), and voting him out is the duty of everyone who holds the Constitution to heart.
Which, unfortunately, isn't all that many people these days.
And what's with the epithet? I never even met Kenny!
Which is not to praise the Weathermen or any of the leftist nutcases of the time, but I'm talking about what the people in the government do with the power they're supposed to be using on my behalf.
I have never, ever seen anything like the reflexive hostility of this administration to normal political opposition. This Bush should expect it; he got into office on a hugely controversial court decision and with fewer votes than his opponent, and has proceeded to embark on an extreme right-wing program targetting access to and even information about birth control, gutting of pollution regulations and the doctoring of scientific information on government websites to conform to a partisan agenda.
Nothing can excuse this. Nothing. And then we read about the arrest and harassment of people whose only act is to register their discontent with the acts of the President, over and over and over.
I have few beefs with the President over the most controversial of his actions, over in a hot, tired and dusty land far away... but the rest of this stuff threatens the very soul of America if it is allowed to continue. So the only thing I can do is to vote the rascal out, as a lesson to him and any who would follow him:
Thou shalt not abridge the freedom of speech, or of the press, or tell falsehoods about the conclusions which our taxpayer-financed research has given us, or let anyone contaminate my air and water for the bonuses of the corporate executive class. Not In My Name.
(And that goes for anyone pandering to the postmodern PC idiotarians on the other side too; throw sops to them, and you've declared yourself my enemy.)
In this case, it's much worse than that. The fish's testicular tissue is claimed to have produced eggs, but you might notice that the article didn't mention anything about the morphological changes required to become a functioning female. If you began producing ova in your nuts would that make you female in any meaningful sense of the word, or just ill?
This phenomenon needs to be analyzed, the cause identified and stopped. If we don't do this, we're going to lose things starting with the fish, and continuing up to ourselves - and if this doesn't worry you, spend some time looking up the literature on hormone mimics, phthalate and the other disturbing stuff that gets to us in eerie ways like leaching out of baby bottles.