the personal fission device

[bwanaaa]

Why cant we have a self regulating fission reactor.

For example, a uranium-plutonium suspension in a carbon matrix gel sitting over a powerful magnet. As the fission reaction cascades and it gets hotter, the heat causes mixing of of radioactive fuel with the moderator thus slowing down the reaction (fission). As the reaction slows and cools, the heavy uranium-plutonium is concentrated towards the magnet which then accelerates the reaction. Regulation of the magnet would allow fine tuning.

Make this reactor the size of a basketball encased in stainless steel. Put one in your basement instead of a gas fired or oil fired boiler-presto-personal nuclear fission.

If apple made this it would be white and in the shape of an apple.

It would last a long time, be impossible to steal (think tons), impossible to blow up (think tamper monitoring over internet (which can be done over power lines also), and be clean and sustainable.

Reminds me of Mr. Fusion in the DeLorean in 'Back to the Future'.

 

[herm0016]

we could use these. http://en.wikipedia.org/wiki/R...ermoelectric_generator

i don't think having a small rector in every home would be a good idea, what happens when people start to get rad. sickness from their heating system? or it has a little melt down?

 

[PottedMeat]

Originally posted by: bwanaaa
Why cant we have a self regulating fission reactor.

For example, a uranium-plutonium suspension in a carbon matrix gel sitting over a powerful magnet. As the fission reaction cascades and it gets hotter, the heat causes mixing of of radioactive fuel with the moderator thus slowing down the reaction (fission). As the reaction slows and cools, the heavy uranium-plutonium is concentrated towards the magnet which then accelerates the reaction. Regulation of the magnet would allow fine tuning.

Make this reactor the size of a basketball encased in stainless steel. Put one in your basement instead of a gas fired or oil fired boiler-presto-personal nuclear fission.

If apple made this it would be white and in the shape of an apple.

It would last a long time, be impossible to steal (think tons), impossible to blow up (think tamper monitoring over internet (which can be done over power lines also), and be clean and sustainable.

Reminds me of Mr. Fusion in the DeLorean in 'Back to the Future'.

Is uranium/plutonium even affected by a magnetic field? And if it is, what if the magnet is disabled, what happens in an external field? This has to be some high temperature gel too.
How is it better than one of those pebble bed reactor things?

A ball sized reactor would be easy to steal, easy to blow up, easy to tamper with ( heh what kind of reliability is monitoring over powerline/internet - you gonna send the cops in every time the signal is lost? ).
Every household having a ball of plutonium/uranium probably isn't a very good idea...

 

[silverpig]

It won't ever work because it's nu-q-lar and that's bad.

 

[QuixoticOne]

That's just ... scary.

Actually some of the very general principles of your ideas for making 'cheap' 'intrinsically safe' generators
are being implemented on industrial scales to generate power. I'm sure if you research various
modern designs being planned/used in Europe you'll find some information about the ways they're trying to make major accident-proof designs.

I don't think we're ever going to see neighborhood scale or home scale generators that work according to
any such principle for political reasons. Even syria and iran and n. korea can't get power plants in place to power their domestic needs without a lot of political / military pressure to stop.

As the previous poster mentioned you can have compact intrinsically safe RTGs like are used on some spacecraft, and there's no reason you couldn't put a steam turbine on a sufficiently hot running unit either for more generation efficiency.

Besides the environmental impact of large scale generation with that technology is bad. What is more interesting is if they can come up with cheap / relatively clean fusion power sources that are practical at any industrial scale. What would be more interesting is if they could be scaled down to community scale to help reduce the need for long distance transmission grids which waste a fair amount of money / resources / energy.

The magnetic bit wouldn't work for lots of reasons mostly relating to various reasons why the material is non-magnetic. One reason even a ferromagnetic material wouldn't be magnetic above several hundred degrees centigrade is the curie temperature limit at which point a substance loses ferromagnetic properties. Actually I'm not sure those metals are strongly magnetic at any temperature room temperature or moderately above it. Lots of metals like aluminium, copper, brass, various grades of steel, nickel, zinc, et. al. are not strongly magnetic (they're not ferromagnets).

Anyway it would also be the case that you wouldn't necessarily use pure metals anyway, they would possibly be various oxides or whatever instead of base metal, again, usually diminishing any magnetic properties that the pure metals might have (excepting the case of the perovskite style YBaCuO2 type superconductors).

Besides a few square meters of sun exposed wall/roof will get you a killowatt or two of solar thermal or photovoltaic energy which is more or less enough (and then some) for a typical US household averaged over seasons / day / night et. al. Much cleaner / better, ditto for small windmills.

 

[Peter]

Why not:

* The world's Uranium supply is far from infinite.
* Plutonium isn't just radioactive, it is also hugely poisonous - you don't want the stuff around people.
* The #1 unanswered question of nuclear power: Where do we put the waste?

 

[bwanaaa]

Originally posted by: QuixoticOne

The magnetic bit wouldn't work for lots of reasons mostly relating to various reasons why the material is non-magnetic. One reason even a ferromagnetic material wouldn't be magnetic above several hundred degrees centigrade is the curie temperature limit at which point a substance loses ferromagnetic properties.

encasing uranium in steel jackets is trivial. the technology is already used to cost effectively jacket palladium103 and iodine192 for implanting into cancers. these 'seeds' are known as radioactive implants and their decay products cause double stranded dna breaks which cancer cells cannot repair as efficiently as normal cells, so they preferentially die. someone who has been implanted is safe to sit next to as the decay products have a short mean path length.

also, the temperature at which the core is operated does not have to be above the curie point.

also failure of the magnet will result in dispersion of the pellets with resulting shut down of the fission due to moderation.

i am all in favor of photovoltaics, but am perplexed at the glacial pace at which it is being developed. The same technolgy hasnt really advanced in 25 years. in fact, the guy that invented nimh batteries came up with an amorphous crystalline pv panel that looks like roof shingles. you can put nails through it and it just keeps working. it's just nt as efficient, but they are using them in africa

http://home.att.net/~africante...orphous/amorphous1.htm

ultimately the chinese will produce these in mass quantities and undercut even our utilities. i can imagine all of china as one giant pv generator.

how do you spell 'economic hostage'?

 

[Cogman]

Do you really want the average joe to have a nuclear power plant in his back yard?

 

[lxskllr]

Originally posted by: Cogman
Do you really want the average joe to have a nuclear power plant in his back yard?

For real. People can't even handle the simple task of taking care of their computers, and you expect them to take care of a nuclear reactor?

 

[KIAman]

I seem to give this same answer to all of these "why not" posts but its true, even though kinda sad.

Cost. The average person cannot afford a multimillion dollar device even if it gives them unlimited hot water.

Regardless of all the other reasons given, if there was a way to make a personal basketball sized nuclear reactor at a reasonable cost, we would find a way to legalize and use them.

 

[Modelworks]

The words dirty bomb comes to mind.

 

[QuixoticOne]

You're sort of wrong. The real problem is political and cost effectiveness, not absolute cost.

Do you know what the crowning capstone of the washington monument is made of?
Pure Aluminium. It was (not so long ago) more valuable than gold and was basically a status symbol of
rarity, value, and technological prowess owing to the great difficulty in refining it. It is never found free
in nature and must be elaborately refined from ores at one of the hugest energy costs out there for
a commodity substance.

For many metals or precious stones it is not uncommon to have to mine and process literally TONS of
ore to get just a few grams of end product.

So if sensible economic cost (taking into account natural capital) had any bearing we'd never be
throwing out aluminium cans and aluminium foil and steel ('tin') cans and generally wasting all the
elaborately refined metals that we (sadly) do. They'd sensibly all cost 'millions'.
We see the cost of Copper skyrocketing already because of limited supply and great demand
(and great waste).

In this case it is just a matter of a difficult refining process of a naturally occurring substance; there's no
reason that the economy of scale could make it cheaper.

And the mechanism doesn't have to be elaborate, after all there are *naturrally operating* reactors
including the ones heating the earth's core keeping it molten. That should suggest something about
the scale of power available compared to the small demands of human industry. Basically at a minimum
it is not much more than a pile of hot rocks with a few thermocouples thrown in, certainly less complex
than your modern air conditioner likely is.

The reasons not to do it are environmental, political, and cost effectiveness compared to other
alternatives like solar / wind and larger community scale power generation technologies.

Generally the bigger the scale of a power generator the more efficient it is due to simple thermodynamics.
At some point it is more economical to have something the size of a city block operating at
90% efficiency providing power for 50,000 homes rather than having something the size of a refrigerator
in each and every home operating at 2% efficiency providing power for just that home. There is an
economy of scale.

But that's not to say it'd intrinsically cost millions any more than your soda can costs $1000.

Originally posted by: KIAman
I seem to give this same answer to all of these "why not" posts but its true, even though kinda sad.

Cost. The average person cannot afford a multimillion dollar device even if it gives them unlimited hot water.

Regardless of all the other reasons given, if there was a way to make a personal basketball sized nuclear reactor at a reasonable cost, we would find a way to legalize and use them.

 

[wwswimming]

Toshiba sells a model of nuclear reactor about the size of a full size truck (20' x 6')

http://www.toshiba.co.jp/nuclearenergy/english/

http://www.nextenergynews.com/...ro-nuclear-12.17b.html

i wonder for how much, $$ wise ?

 

[futuristicmonkey]

Originally posted by: Peter
Why not:

* The world's Uranium supply is far from infinite.
* Plutonium isn't just radioactive, it is also hugely poisonous - you don't want the stuff around people.
* The #1 unanswered question of nuclear power: Where do we put the waste?

Waste is not an issue, nor should have ever been one.

In Canada, our answer is the DUPIC cycle. Scroll down a little, to CANDU/LWR Synergism. Spent fuel from typical reactor can bred to make more fuel in a variety of ways (while producing electrical power at the same time). The waste issue is only an issue due to government bureaucracy. Unfortunately, your average voter is apparently more intelligent and more versed, in these matters, than the engineers who design and build these things.

 

[wwswimming]

Originally posted by: futuristicmonkey

Originally posted by: Peter
Why not:

* The world's Uranium supply is far from infinite.
* Plutonium isn't just radioactive, it is also hugely poisonous - you don't want the stuff around people.
* The #1 unanswered question of nuclear power: Where do we put the waste?

Waste is not an issue, nor should have ever been one.

In Canada, our answer is the DUPIC cycle. Scroll down a little, to CANDU/LWR Synergism. Spent fuel from typical reactor can bred to make more fuel in a variety of ways (while producing electrical power at the same time). The waste issue is only an issue due to government bureaucracy.

actually it's an issue for anyone who lives in a country America has
used military force against since about 1991, the first Iraq war.

the US transfers depleted uranium to companies like ATK and makes
various size munitions out of it.

the net result - hundreds of tons of nuclear waste blowing around
Iraq, Yugoslavia, and Afghanistan - to be inhaled by civilians and
American and coalition troops.

all this talk of terrorists & "dirty bombs" ... if just one of those
devices was used on American soil, it would be a Very Big Deal.

the American nuclear industry has a clear policy about nuclear waste -
turn it into dust and let foreigners breathe it.

http://www.google.com/search?h...ium&btnG=Google+Search

 

[dkozloski]

Originally posted by: wwswimming
Toshiba sells a model of nuclear reactor about the size of a full size truck (20' x 6')

http://www.toshiba.co.jp/nuclearenergy/english/

http://www.nextenergynews.com/...ro-nuclear-12.17b.html

i wonder for how much, $$ wise ?

Toshiba is working on a project with the remote Alaskan town of Galena to install a Toshiba packaged powerplant buried underground. It looks very attractive economically.

 

[ajaidevsingh]

Tough this is possible but the safety term is not fixed.

Even a small nuclear rector can cause a huge meltdown the only difference would be falout rate and distance....!!

Other than this mild radiation effects can be trouble "Sperm are the first to die in mild radiation"

 

[dkozloski]

A rough number for the extent of a meltdown is that the heat liberated would be about equal to the capacity of the plant. In other words, a 10MW plant would have about a 10MW meltdown. A meltdown is actually a pretty good result. The fissionable material would be encased in molten rock which would turn to glass when it cooled. The Toshiba plant at Galena would actually have the reactor and cooling system buried 30 meters deep in the ground. Plant capacity would be 10MW. The initial fueling would last 30 years and then the reactor would be dug up and traded for a replacement unit.

 

[bwanaaa]

tnx for the toshiba llinks. this makes me feel good and bad. Good because a REAL business like toshiba has made it a reality and effectively eliminated all of the luddites in this thread who said it cannot be done. BAD because I thought I had an original idea but in fact it was conceived, planned and executed already by someone else. I think there was an article in the Atlantic or was it Wired- that google is making us stupider. Effectively, anything you can think of, has already been done by the japanese/chinese/koreans.

I wonder how the lithium6 reactor actually works. If the lithium is the moderator which is in a tube at the core, how does it moderate? Does it become a more effective moderator as it liquifies at higher temperatures? I wonder at what temp this reactor operates? 200 kw is enough for a small american neighborhood and the cost of 5 cents per kwh is astounding.

I do not understand the efficiency argument posted above. If someone is knowledgeable enough to prove with REAL numbers how that might be true, I would appreciate it. Please also include in the calculation, transmissive losses from a central powerplant as well as costs of a distribution system and its maintenance.

In terms of dirty bomb/political arguments--the only dirt is the 50 feet on top of the core. even a hardened 2000 lb JDAM dropped onto it could not get to it.

 

[Gibsons]

Originally posted by: bwanaaa
In terms of dirty bomb/political arguments--the only dirt is the 50 feet on top of the core. even a hardened 2000 lb JDAM dropped onto it could not get to it.

The concern isn't someone blowing up the reactor itself - the concern is that it's a relatively easy to get source of uranium/plutonium. ie - get it installed in the back yard of your very remote compound in west middle-of-nowhere, dig it up, remove the fuel and you're ready to go. it might take you a week or a month or a year to dig it up (you can rent a back hoe easily enough), but that's much easier than breaking into a large plant.

 

[QuixoticOne]

http://en.wikipedia.org/wiki/Carnot_efficiency

The theoretical maximum efficiency of any heat engine depends only on the temperatures it operates between. This efficiency is usually derived using an ideal imaginary heat engine such as the Carnot heat engine, although other engines using different cycles can also attain maximum efficiency. Mathematically, this is because in reversible processes, the change in entropy of the cold reservoir is the negative of that of the hot reservoir, keeping the overall change of entropy zero. Thus:
Efficiency Max = 1 - Thot / Tcold ; where temperatures are in Kelvin.

http://en.wikipedia.org/wiki/Curie_temperature

also, the temperature at which the core is operated does not have to be above the curie point.

As you can see, the maximum possible (Carnot) efficiency of any heat engine (given by the laws of thermodynamics) operating with a hot temperature of 1000K and a cold temperature of 298K is approximately 70% with real world values being substantially less.
You're down to 50% at a hot temperature of 600K. It does matter significantly to efficiency that any thermal power plant be operated at as high a temperature as practical at its hot side and as cold a temperature as possible at its cold side.

You really need to learn a lot more about materials science and several branches of physics before you can understand the essential criteria that are in play in making any kind of power plant safe, efficient, reliable, et. al. There are many advanced subjects in many branches of science and engineering. Yes, it would be nifty if we had small, cheap, perpetual, reliable sources of power, but the hard part is in the details, not the in the dream / concept. I think everything that can practically be done with thus sort of power is pretty much already well understood and people are pursuing what is practical, politically acceptable, and economical. I didn't say safe since obviously there have been many cases where it hasn't been done particularly safely, and, actually, a lot of it hasn't been economical either come to think about it.

I suppose it could be an interesting mental / academic exercise to understand the generalities of how some kind of power plant might work in generalities, but really there are no revolutionary ideas in new efficiencies to be had in this area. Even if there were, it'd be pretty unlikely to catch any serious attention, things change at a pretty glacial pace in big industry and government especially in areas like this.

If you really want to make a contribution, I'd say you're studying the wrong branch of engineering concepts; photovoltaic, wind, geothermal, or even fusion are areas where there is a lot of undeveloped potential for industrial development.
This is a dead end politically, environmentally, economically, et. al. AFAICT.

The difference between what is practical and what is insane is just too complex to lend itself to this sort of non-technical discussion, again, there are many complex details and 'almost' doesn't count.

Originally posted by: bwanaaa
tnx for the toshiba llinks. this makes me feel good and bad. Good because a REAL business like toshiba has made it a reality and effectively eliminated all of the luddites in this thread who said it cannot be done. BAD because I thought I had an original idea but in fact it was conceived, planned and executed already by someone else. I think there was an article in the Atlantic or was it Wired- that google is making us stupider. Effectively, anything you can think of, has already been done by the japanese/chinese/koreans.

I wonder how the lithium6 reactor actually works. If the lithium is the moderator which is in a tube at the core, how does it moderate? Does it become a more effective moderator as it liquifies at higher temperatures? I wonder at what temp this reactor operates? 200 kw is enough for a small american neighborhood and the cost of 5 cents per kwh is astounding.

I do not understand the efficiency argument posted above. If someone is knowledgeable enough to prove with REAL numbers how that might be true, I would appreciate it. Please also include in the calculation, transmissive losses from a central powerplant as well as costs of a distribution system and its maintenance.

In terms of dirty bomb/political arguments--the only dirt is the 50 feet on top of the core. even a hardened 2000 lb JDAM dropped onto it could not get to it.

 

[dkozloski]

A local resort that features a hot springs has partnered with United Technologies to develope and demonstrate a power plant that is using geothermal energy combined with a turbine that operates off of air-conditioning refrigerant to run a 400Kw powerplant.
http://www.popularmechanics.co...nce/earth/4245896.html

This isn't a pipe dream or a theoretical exercise. It really works and there is no radiation whatever.

 

[bwanaaa]

so quixoticone,

you seem to be quite knowledgeable. how does the lithium6 reactor moderate the cascade without control rods?

 

[Gibsons]

Originally posted by: bwanaaa
so quixoticone,

you seem to be quite knowledgeable. how does the lithium6 reactor moderate the cascade without control rods?

This is weird. I've been googling for bit and can't find one shred of text about this reactor on Toshiba's website. Nothing about microreactors or lithium-6 at all. I find that same blurb (as linked in wwswimmings post) over and over all over the net, but nothing on Toshiba's website.

What's more, it seems Li-6 is an odd choice - if you hit Li-6 with neutrons you get tritium. That doesn't seem good, unless you're using the tritium for something else and that doesn't seem likely.

 

[QuixoticOne]

Off the top of my head I'm not sure, it isn't my field. I could research it but not much more easily than anyone else could. Especially since it seems like the source of the information isn't even able to be traced to any official specifications from the manufacturer, it may be difficult to conclude that that's even what's really going on. It wouldn't be the first time that some scientifically clueless marketing / reporter type tried to "summarize" or "dumb it down" and end up with a statement that is just plain wrong / nonsensical technically.

Anyway the question about "how" it does it is a bit ambiguous too. The basic "how" is pretty obvious (I'd guess), the "why" they chose that specific material and configuration as opposed to some other is probably a much more insightful / complicated one to answer. To really see why something is suitable you'd have to understand all the thermal, chemical, mechanical, material durability, physics related properties of the entire system over a range of temperatures, pressures, chemical environments, physical configurations and see if the result is stable within the desired operating range and how stable it is.

It wouldn't be surprising if even mechanical aspects came into play. Look at the difference between a carbon arc light and the early char / cotton filament incandescent bulbs. The exact mechanical / chemical thickness and level of "charring" was very important for success. The electrodes in a lead acid battery not only have to be made of the right substance but have to have their porosity and micro crystalline structures fabricated in just the right way for optimum efficiency. Semiconductors aren't just hunks of silicon, but all kinds of
material preparations, crystal orientations, atomically thick coatings / impurities, et. al. are all very relevant.

I suspect you're not going to find the level of detail that will let you really totally understand in detail anything but the most gross engineering / materials science aspects how it works or why it was done in such a way and what compromises exist in a given design. I expect that if you did investigate it you'd quickly find a lot more detail than you wanted to learn, and even then there'd be more questions than answers.

To design and model such things for safety and efficiency is why they're building petaflop level clusters with 100,000+ CPUs at the national labs and so on. The generalities may be simple but the specifics of what really happens at a given temperature / pressure / operating point / operating history with a given
probability of X mechanical tolerances or impurities present or whatever is a non-trivial question.

If you'd like to find out more about the engineering aspects, I'd look for some real books on the subject, as well as maybe learning about the published regulatory / safety / approval guidelines, academic papers, et. al.

Originally posted by: Gibsons

Originally posted by: bwanaaa
so quixoticone,

you seem to be quite knowledgeable. how does the lithium6 reactor moderate the cascade without control rods?

This is weird. I've been googling for bit and can't find one shred of text about this reactor on Toshiba's website. Nothing about microreactors or lithium-6 at all. I find that same blurb (as linked in wwswimmings post) over and over all over the net, but nothing on Toshiba's website.

What's more, it seems Li-6 is an odd choice - if you hit Li-6 with neutrons you get tritium. That doesn't seem good, unless you're using the tritium for something else and that doesn't seem likely.