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Clean nuclear for my starship.


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#1 silverslith

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Posted 07 April 2007 - 03:36 AM

I've mentioned proton activated fission of lead but I wonder if theres some alternatives that might be nicer.:)

Like a gamma throttled alpha reactor based on U236. With its half life of 23million years its pretty cool. You could stimulate it to decay to thorium232 which is the most stable actinide known by hitting it with tuned gamma photons. Even once you'd burnt it all you could do it all again with the Thorium if you needed to. . U238 would be OK and is given away by the nuclear industry.It may be possible to do this with any decent sized atoms that are prone to alpha decay, not just the actinides

Alpha throttled fission is potentially possible too but i'm just not keen on hundreds of fission products and the critical mass problem.

#2 silverslith

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Posted 09 April 2007 - 02:29 AM

QUANTUM NUCLEONICS is looking darn interesting.:hot:

Researchers move closer to switching nuclear isomer decay on and off

Public release date: 6-Apr-2007
Contact: Anne Stark
stark8@llnl.gov
925-422-9799
DOE/Lawrence Livermore National Laboratory

Researchers move closer to switching nuclear isomer decay on and off
LIVERMORE, Calif. -- Livermore researchers have moved one step closer to being able to turn on and off the decay of a nuclear isomer.

The protons and neutrons in a nucleus can be arranged in many ways. The arrangement with the lowest energy is called the ground state and all others are called excited states. (This is analogous to the ground and excited states of electrons in an atom except that nuclear excited states are typically thousands of times higher in energy.) Excited nuclear states eventually decay to the ground state via gamma emission or to another nucleus via particle emission. Most excited states are short-lived (e.g., billionth of a second). However, a few are long-lived (e.g., hours) and are called isomers.

Turning the decay on and off is key to using isomers as high-energy density storage systems such as batteries.



Gamma-ray laser

The advance of technology makes ever increasing demands upon high powers. At present the highest are EXAWATT POWERS (10^18 Watts), which are encountered in concepts for advanced propulsion technologies, directed energy beams, sterilization countermeasures against biological weapons, photothermal countermeasures against chemical weapons, full-scale nuclear simulators, and laser fusion reactors for commercially competetitive power generation.


Hafnium-178m, the isomer studied by Becker’s team, has a long half-life of 31 years and a high excitation energy of 2.4 megaelectronvolts (MeV). As a result, 1 kilogram of pure 178mHf contains approximately 1 million megajoules (10^12 joules) of energy. Some estimates suggest that, with accelerated decay, 1 gram of 100-percent isomeric 178mHf could release more energy than the detonation of 200 kilograms of TNT.


The 31-yr half-life for the gamma decay of a sample of 178Hf isomeric nuclei
has been accelerated 2% by irradiating it with x-rays from a small device
normally used in dental medicine. There are very significant implications
of this work.


A survey of 19 isotopes conducted with the four U.S. accelerators over a fairly coarse mesh of bremsstrahlung endpoints confirmed the existence of giant resonances for transferring K in the region of masses near 180 as shown in Fig. 4. Activation edges continued to support the identifications of integrated cross sections for pumping and dumping of isomers that were of the order of 10,000 times greater than usual values.


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#3 GAHD

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Posted 09 April 2007 - 09:47 PM

Other than the weight, something like lead cooling for your reactor might be nice. circulating radioactive coolant as a protection vs cosmic rays. yay!

#4 silverslith

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Posted 10 April 2007 - 01:08 AM

Other than the weight, something like lead cooling for your reactor might be nice. circulating radioactive coolant as a protection vs cosmic rays. yay!


I'm trying to steer clear of neutron technologies so my coolant doesn't get activated. The Lead fisson reactor is becoming less attractive to me for this reason as alternatives look promising. Neither Hafnium isomer or photoalpha would suffer this problem.

On the subject of charging our hafnium batteries, the attached pic from Gamma-ray laser shows that the energy release from hf178m2 is in several separate photons of sub gamma energy. This is a clear indication that several intermediate quantum nucleonic states are traversed by the nucleus in transitions between ground state and the stable higher energy isomers. While charging hf178 to hf178m2 has been so far done by huge and inefficient high energy gamma sources with low efficiencies, I'm speculating that the best way of doing it may be with a rapid succesion of sub gamma photons of precise quanta equal to each rung in the ladder.:hyper:

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#5 Larv

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Posted 15 April 2007 - 10:08 AM

Hi, silverslith,

I'm not really sure how to reply to your OP question. I am supposing that nuclear fuels would empower your starship to make deep-space voyages...that clean nuclear fuels would serve especially well for that purpose. Here's what I thing about it.

Firstly, I'd much rather see robots venturing out into deep space than torporated humans. The idea of deep-space travel by humans is romantic and foolish. Secondly, nuclear fuels may not be necessary or worth the risk of launching. Robotics could endure time-consuming propulsion schemes using gravitation slingshots and other means that would otherwise impose temporal constraints on biological life. Time would be the biggest issue for your deep-space starship, not its propulsion system. (I'm assuming there is already plenty of external energy available for propulsion, but my assumption is speculative.)

And one more thing about nuclear fuels in space rockets: Didn't SNAP-9A prove that the launching risk is unacceptable with nuclear fuels are on board? BTW: Do they still launch rockets with nuclear fuels on board? I frankly don't know.

—Larv

#6 InternationalSpaceAgency

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Posted 15 April 2007 - 10:04 PM

A starship would be best to use antimatter for its fuel source, as this would be the most propulsion for the mass and weight of fuel.

Also, for some intersteller missions, and intersolar missions, a liquid mass cytrifical propulsion system powered by a nuclear reactor would be the best system, as you do not need to carry fuel around.

#7 silverslith

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Posted 16 April 2007 - 12:02 AM

A starship would be best to use antimatter for its fuel source, as this would be the most propulsion for the mass and weight of fuel.

Also, for some intersteller missions, and intersolar missions, a liquid mass cytrifical propulsion system powered by a nuclear reactor would be the best system, as you do not need to carry fuel around.


Certainly matter antimatter reactions are the most energy per mass. While antiproton creation and storage are advancing and the best yet known in this field, the best that can be achieved is still a fraction of a seconds worth of fuel for a starship. The most achievable system is currently saltwater nuclear rockets which are so dirty they cannot be acceptable inside the orbit of jupiter and antimatter reactions are just as dirty.

#8 InternationalSpaceAgency

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Posted 16 April 2007 - 12:05 AM

?? What!

Is the #5 married or single!?

:piratesword:


Certainly matter antimatter reactions are the most energy per mass. While antiproton creation and storage are advancing and the best yet known in this field, the best that can be achieved is still a fraction of a seconds worth of fuel for a starship. The most achievable system is currently saltwater nuclear rockets which are so dirty they cannot be acceptable inside the orbit of jupiter and antimatter reactions are just as dirty.



#9 silverslith

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Posted 16 April 2007 - 12:09 AM

Hi, silverslith,

I'm not really sure how to reply to your OP question. I am supposing that nuclear fuels would empower your starship to make deep-space voyages...that clean nuclear fuels would serve especially well for that purpose. Here's what I thing about it.

Firstly, I'd much rather see robots venturing out into deep space than torporated humans. The idea of deep-space travel by humans is romantic and foolish. Secondly, nuclear fuels may not be necessary or worth the risk of launching. Robotics could endure time-consuming propulsion schemes using gravitation slingshots and other means that would otherwise impose temporal constraints on biological life. Time would be the biggest issue for your deep-space starship, not its propulsion system. (I'm assuming there is already plenty of external energy available for propulsion, but my assumption is speculative.)

And one more thing about nuclear fuels in space rockets: Didn't SNAP-9A prove that the launching risk is unacceptable with nuclear fuels are on board? BTW: Do they still launch rockets with nuclear fuels on board? I frankly don't know.

—Larv


Unfortunately snap pu 238 is very common now. If starwars goes ahead they plan to put 2+ tonnes of pu in near earth orbit per unit. Robots- fine but they are only an advantage if superhuman accelerations are required and as relativistic time dilation is available at far lower accelerations than superhuman in a few months I'd rather go myself for many reasons.
Thought you'd jump at the chance to show that HRW is useful as clean nuclear fuel:hihi: .
Nuclear is the only way to use reaction mass effectively enough for interstellar. Since clean technologies are basically available now, I say we go.:piratesword:

#10 ronthepon

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Posted 16 April 2007 - 03:56 AM

How do you use nuclear fuel to propell rockets anyway? Heat can be produced, but for the thrust, you'll need some mass to be ejected right?

#11 Turtle

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Posted 16 April 2007 - 04:03 AM

How do you use nuclear fuel to propell rockets anyway? Heat can be produced, but for the thrust, you'll need some mass to be ejected right?



I'm a nube to all this, but here's something that caught my interest. (OK, so I googled 'nuclear rocket design' and picked the first non-wicki article; sue me:hyper: ):lol:

Dumbo Nuclear Rocket Reactor Design

#12 ronthepon

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Posted 16 April 2007 - 05:38 AM

Apparently, the access is restricted to the site. I cannot seem to access it.

BTW, look who's got te devil's number as a rep power.

#13 ronthepon

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Posted 16 April 2007 - 05:50 AM

After some googling myself, I also found this link.

From what I read, te procedure eventually used a stored amount of hydrogen. The hydrogen is suddenly heated using nuke power, and ejected. Which does not make it aeons better than the other methods though. The hydrogen still would be limiting.

#14 Boerseun

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Posted 16 April 2007 - 06:15 AM

I read about an idea once (have no idea where) of using helluva strong inertial plates outside the spaceship against which conventional nuclear bombs are exploded. You'll have a heck of a lot of thrust, but almost everything will be spent in a small fraction of a second, most likely ripping everything inside the spaceship to shreds.

Another interesting idea is to create a very strong magnetic field (as big as you want, depending on your equipment - which still needs to be invented) and explode a nuclear bomb *inside* this magnetic bubble. A small opening in the magnetic "bubble" would be left open, and the plasma will escape through there, creating thrust in the opposite direction. The thrust can be controlled by altering the shape of the magnetic field, and the size and direction of the opening will determine the direction and amount of thrust required.

Do not, however, ask me how they intend to create such a strong magnetic field...

...but it seems like a good idea, and a very good application of the nuclear weapons currently lying idly around making the militarily-inclined's collective trigger fingers itch like a naked, sweaty fat man in a mosquito infested swamp with his hands tied behind his back and no insect repellent in a ten mile radius, at about 40 degrees Celcius with humidity at 99% and no movement in the air, save for the incessent buzzing of millions of hungry blood-thirsty mosquitoes rising in timbre and fortissimo, coming closer, closer, ever closer, the noise rising to the point where the faint buzzing is replaced by a dull roar which is suddenly silenced by a drop of sweat clogging up his eardrums. But I digress.

It's a good idea, but how to build such vast magnetic fields? And what kind of power would you need to magnetically contain a nuclear explosion?

#15 ronthepon

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Posted 16 April 2007 - 06:33 AM

The good concept, however, we still need to do some thinking on it. Unfortunately, a magnetic bubble can, at the most prevent the particles from escaping, but I'd expect te radiation to leak out nevertheless.

About the solid idea, I found myself explaining to someone that tantalum halfnium carbide melts under 5000K, and it has the highest MP for a known solid. Yet, it's much lower then the temperatures a nuke blast would produce.

However, suppose we allowed the gases to leave so rapidly, that the walls don't actually get the time to seriously heat up, this could be viable.

Suppose we contaminate the nuke fuel to an extent where it actually is spent somewhat slowly?

#16 ScottKreiger

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Posted 16 April 2007 - 07:40 AM

My 1rst Q is what do you want the Nuke energy for, exactly?
My 2nd Q is, do you know about the gyro scopic space drive? I have a paper model that I am VERY sure will work.

#17 Boerseun

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Posted 16 April 2007 - 07:50 AM

My 1rst Q is what do you want the Nuke energy for, exactly?
My 2nd Q is, do you know about the gyro scopic space drive? I have a paper model that I am VERY sure will work.

Info? Links? Pics?

Can you explain this gyro space drive?

I assume the only good reason for a nuclear drive will be the vast amount of energy locked up in fuel weighing very little. All other fuels are way too heavy when compared against nuclear. The ideal, of course, would be antimatter, but to produce a gram of the stuff would consume something like twice the entire world's GDP. Nukes, on the other hand, are two a penny, when compared to antimatter. Only problem with nukes is how to unleash the energy slow enough, ironically. I think Ron might have a point in contaminating the fuel, but that's also a dodgy proposition, seeing as contamination might actually prevent fission from taking place.