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See: http://www.ibiblio.org/lunar/school/Int … ...ms.HTML
for: " For example: Bussard fusion reactor with a radius of about 2.5-3 meters burning P+11B (hydrogen and Boron-11) produces 4500-8000 megawatts (4.5-8 E9 watts) of electricity and weighs about 14 tons (.00174 kg per KWe (575 KWe/Kg)). That's enough electricity per reactor to power a couple of big cities, and will be the standard power plant of most of our support craft. This isn't nearly enough power for the drive systems of one of the Explorer ships of course, but the system can be scaled up and retain its efficency.
This design is Bussard's variation of the Farnsworth/Hirsch electrostatic confinement fusion technology. Whats important to us is that it makes such a fantasticly small light power plant, that it can be used as part of a high thrust to weight ration propulsion system for space craft and aircraft. Bussard and associates have designed propulsion versions with a specific impulse of between 1500 and 6000 sec. (Best chemical specific impulse is 450.) I'll discus the rocket applications below. " ... and more!
also --http://www.focusfusion.org/symposiumfinal.htm
and somev google-ing for investigation about the feasibility of overwhelming the X-ray plasmic bremsshalung and the possibility for net-gain aneutronic reactors.
Also wiki or google for "collision beam fusion reactor".
They seem VERY good for interplanetary trips. Two months to Titan, two-three weeks to Mars...
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Ehhhh falls under the catagory of "too good to be true"
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Aren’t the problems with nuclear powered vehicles mostly to do with getting rid of a large amount of heat. The reactors of JIMO are only the size of a bucket and they produce a fair amount of power. I know some nuclear propulsion designs keep the core cool by cooling it with the exhaust stream. I wonder how much solid core propulsion could be improved before more exotic techniques are tried.
In the case of a 4500-8000 MW reactor even at 99% effeciency that is 45-80 MW of heat that the system must get rid of. How much will the radiator weigh?
Dig into the [url=http://child-civilization.blogspot.com/2006/12/political-grab-bag.html]political grab bag[/url] at [url=http://child-civilization.blogspot.com/]Child Civilization[/url]
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Well, the higher the temperature you operate the reactor at, then the less radiator area you need per-watt that you need to reject. For reactors with gas (usually He or Ar) radiator cooling, you can't run these all that hot, requiring big radiators like JIMO. Reactors with liquid metal running through the radiators, they can be pretty small, like the SP-100 reactor. The tradeoff being, liquid metal cooled reactors with thermoelectric converters (like big RTGs) instead of gas turbines like JIMO have lousy efficency (~5% versus 33%). SP-100 makes up for this by having a really powerful reactor (two megawatts versus three hundred kilowatts), since its easier to make a bigger reactor then a bigger radiator... Why NASA is going the gas cooled route I don't know, probobly to make bigger reactors later or somthing.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I know there are terrestrial reactors which use liquid metal (usually sodium) yet have good-excelent effeciency. But they require a secoundary cooling loop, which adds to the mass of the system.
He who refuses to do arithmetic is doomed to talk nonsense.
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The original SP-100 wouldn't have had such a loop I don't believe and would pump liquid metal reactor coolant into the radiators directly, which made them very very small compared to JIMO and such.
The exotic vapor-core reactor would also run at least part of its primary coolant through the radiators, which makes a reactor of that high power (tens of megawatts up to a quarter gigawatt) practical by keeping the radiator dimensions under control.
I don't know what NASA is thinking, but I worry that the radiator size will kill a Mars base reactor.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I don't know what NASA is thinking, but I worry that the radiator size will kill a Mars base reactor.
I suppose there are reasons to reactor efficiency for size and power. A smaller reactor will appease the enviro nazzi’s and reduce the amount of crew shielding required. Also for scientific missions like JIMO it is probably better to trade efficiency for thrust/power. Anyway I think JIMO has several different types of reactors it is testing and some may be better suited for other cooling systems.
Dig into the [url=http://child-civilization.blogspot.com/2006/12/political-grab-bag.html]political grab bag[/url] at [url=http://child-civilization.blogspot.com/]Child Civilization[/url]
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The enviros won't be happy any which way... launching 1,100lbs of HEU versus 1,400lbs of HEU doesn't make much difference to them. (the masses of Uranium needed for a NASA DRM type mission w/ 100lbs for each NTR engine and 100 vs 200lbs for each power reactor). There must be a technical reason.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Yup it is called where will we get the uranium.
With all the recent Los alamo problems of security and even the Horizon mission to Pluto being down sized with regards to the available energy levels from the uranium that can be supplied.
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Not quite. The Pluton mission or future NASA missions that use RTGs or DIPS units use Plutonium-238, not the Uranium-235 (which is fairly plentiful) that a nuclear engines or nuclear reactors use.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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If there is a shortage in plutonium, then this might be a good time to try out the new RTGs that project Prometheus is developing. By using more efficient Stirling heat engines instead of the less efficient thermocouples, the new RTGs will reduce the amount of plutonium that is needed by at least 2/3.
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