Why You Cannot Build a Nuclear (Fission) Reactor At home

June 16th, 2013

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What a nuclear reactor is:

In order to continue, it is important to first qualify exactly what a nuclear reactor is.  In some sense, one could consider any device in which a nuclear reaction occurs to be a reactor, regardless of the type of reaction.   By this definition, combining an alpha emitting isotope with aluminum or beryllium would be a nuclear reactor, since some of the particles will be absorbed and produce a simple nuclear reaction.

Within most context, however, the term “nuclear reactor” is understood to mean a fission reactor.  That is, a device which produces a sustained fission chain reaction using a material like uranium or plutonium.  This normally means that the reactor must achieve critical mass.  However, fission can also be achieved in a sub-critical mass by producing neutrons from an external source such as an accelerator in what is known as a subcritical reactor.

Nuclear fusion reactors are completely distinct from nuclear fission reactors.  Although a nuclear fusion reactor could be called a “nuclear reactor,” doing so, without qualification, is likely to cause confusion.  Nuclear fusion reactors come in a variety of types and it is possible for advanced amateurs to build simple electrostatic fusion reactors, such as the Farnsworth Fusor using commercially available materials.   While these fusors are indeed true fusion reactors, in that they can produce nuclear fusion, the amount of fusion they produce is very small and the neutron radiation generated is low enough to make them relatively safe to operate.   They do not require any radioactive materials for construction or operation.

Once in a while you will see a story in the news about an amateur building a “nuclear reactor” for a science fair or demonstration.   This generally means that they have constructed a fusion reactor, usually in the form of a Farnsworth Fusor.  While doing so is certainly an accomplishment and a very advanced amateur science project, it is not a “nuclear reactor” in the sense of a fission reactor.   It produces no usable energy and only limited neutron flux.

Building a fission reactor is something else entirely.

Why this is just a bad idea:

First of all, if you were to build a nuclear reactor at home, you could very easily kill yourself from radiation poisoning.  Real nuclear reactors require a substantial amount of shielding, usually in the form of water and a material like concrete.   Without enough shielding, exposure to the core neutrons could be fatal, even from a relatively small reactor.  Unshielded nuclear reactions have occurred during criticality accidents, and have caused serious injury or death.   Any reactor that produces more than about a watt of power should be, at the very least, operated at the bottom of a pool of water.   Thankfully, no amateur is likely to get this far.

Many of the other materials used in attempts to build amateur nuclear reactors are quite dangerous.

Uranium is toxic, though only mildly so.   However, extracting uranium from ores or other materials requires a strong acid or base solution, which can be dangerous to handle outside of properly controlled settings.  Am-241, the isotope found in smoke detectors, is highly radioactive.  It is extremely safe, as long as it is kept in the form of a ceramic embedded in gold foil, but if it is extracted, even small amounts can be very hazardous if inhaled.

Some amateurs have used radium-226 in their reactor experiments.  It’s a powerful alpha emitter which can be obtained with relative ease from the luminous paints found on old clocks, aircraft instruments and gauges.   Radium-226 is extremely radio-toxic and is easily absorbed.  It is rapidly incorporated into bones and teeth.  The radium salts found in radium paint also have a nasty tendency to stick to surfaces, making decontamination difficult.  Flaking radium paint can produce dust that is easily inhaled.   Hence, working with radium is dangerous and should be avoided by amateurs.

One of the reasons radium is desired is that it is a high energy alpha emitter, which can be used to produce neutrons when combined with beryllium.  Beryllium is yet another dangerous material that should not be handled by those who lack the proper experience and equipment.  Beryllium is highly toxic, especially when inhaled.  Beryllium dust is easily kicked up into the air and inhaling even small amounts can be extremely harmful.

Examples of those who have tried to make homemade reactors:

David Hahn David Hahn gained fame as “The Radioactive Boyscout” when in 1994 he attempted to build a nuclear reactor in his parents tool shed. Hahn was only 17 at the time and managed to build an impressive amount of material, given that he built his device before sites like eBay were widely available.

Hahn’s materials included antique clocks, smoke detectors, lantern mantels, uranium mineral samples and small amounts of uranium, which he obtained from a chemical supplier.  In order to extract and purify the materials, Hahn also used lithium, derived from lithium batteries, household bleach, saltpeter and other common chemicals.   Hahn managed to conduct some pretty complex and advanced chemical reactions including the synthesis of nitric acid, which he used to extract and concentrate uranium.

He was almost entirely self-taught, relying on library books on chemistry and nuclear energy along with advice he received from the NRC and other government agencies.  Hahn posed as a professor and wrote letters asking for advice on how to conduct small-scale classroom demonstration experiments.

Hahn’s “reactor” was basically a neutron source which he created by collecting radium from antique clocks and americium from smoke detectors, which he combined with aluminum. The neutrons were produced when high energy alpha particles struck the aluminum creating a tiny number of fusion reactions  He started off with a simple “neutron gun” consisting of the alpha emitting material in a lead block with a piece of aluminum foil on one end.  He later upgraded his neutron source by securing a strip of beryllium, a more potent producer of neutrons than aluminum.

Using this simple neutron source, Hahn was able to irradiate materials with enough neutrons to produce a detectable increase in radioactivity.   By focusing his neutron source on thorium, which he had extracted from lantern mantles, he was able to create a tiny amount of uranium-233.   Based on the success of his initial experiments, Hahn hoped to create enough uranium-233 to produce a true nuclear reactor.

The next step was to convert the neutron gun into a kind of “core” by combining the alpha emitting material and beryllium and surrounding the neutron source with moderating material, which he constructed out of tritium-based paint, amongst other material. (whether or not this worked better than a cheaper moderator seems suspect.) He used this neutron source to irradiate thorium, which he had extracted from lantern mantels and uranium, which he had ordered from a chemical supply company. His hope was that the neutron radiation would convert the thorium into fissionable uranium-233 and the uranium into plutonium.

The device did indeed produce some uranium-233 and plutonium, but only in microscopic quantities. It could be described as a “breeder reactor” in this sense, as it did breed some fuel, albeit far too little to be a viable fuel source. It was not a true reactor in the conventional sense, however, because it never achieved a fission chain reaction or even came close.   That said, he had managed to concentrate enough radioactive material to be detected some distance away and, based on some reports, the neutron flux may have been high enough to increase the total radioactivity of the material through neutron activation, and therefore, would presumably have been producing a steady stream of U-233 and Pu-239, although in tiny quantities.   This is a pretty impressive achievement for a 17 year old.

Still, he managed to create quite a mess with his experiments. After being questioned by police for the routine complaint of “loitering” the material was discovered in his car, leading to an investigation, ultimately resulting in his shed being torn down and declared low level radioactive waste. Whether this was necessary might be debated, but clearly his activities were not safe from either a radiological or chemical standpoint.   All things considered, it’s pretty amazing that the authorities did not overreact and evacuate the whole town, but this was in 1994, before paranoia had reached its current levels.

Hahn’s device, which I hesitate to call a reactor, was truly a testament to backyard ingenuity and an accomplishment for someone of his limited means.  Still, it was not the safest thing to do, from an industrial hygiene perspective and certainly is not recommended.

Richard Handl – If David Hahn’s experiments seem a bit dangerous, Richard Handl’s are just plain stupid.  Mr. Handle, of Sweden, seems to have come up with the idea of building a nuclear reactor in the kitchen of his small apartment. Like David Hahn, Richard Handl tried to build his reactor using a small amount of uranium as well as americium (from smoke detectors) combined with radium and beryllium, creating a makeshift neutron source.

You can read about his experience on his blog “Richard’s Reactor.“   He was apparently doing this entirely in public (at least on his blog) but didn’t seem to get the attention of any authorities, until he eventually decided to ask the Swedish government whether what he was doing was legal.  The result was a visit from the police and the confiscation of his materials.  He was charged with illegal possession of hazardous chemicals, impersonation of another person and violation of radiation safety law.   At least word, the first two charges were dismissed. It’s unlikely he’ll end up in prison, but his actions were still amazingly stupid.

The materials Mr. Handl acquired are safe on their own, but he certainly did not handle them safely.   Americium is perfectly safe, as long as it remains in the stable form of a smoke detector tablet.  Radium-226 is generally safe in the form of antique luminescent paint, as long as the paint remains relatively intact is not scraped or dissolved from things like clock faces.  Beryllium is a toxic metal – relatively safe as long as it remains in a solid mass, but should never be ground, machined or otherwise worked without proper precautions.

The image to the right shows what happened when Richard Handl tried to cook the materials on his kitchen stove! Note the large number of cigaret butts, a bottled soft drink and what appear to be candies or gift boxes – this was not a sterile and controlled laboratory!

Here is what he had to say about the spill:

A meltdown on my cooker!!!
No, it not so dangerous. But I tried to cook Americium, Radium and Beryllium in 96% sulphuric-acid, to easier get them blended. But the whole thing exploded upp in the air…

Of cource I thrown away my pills at the left side, and I didn’t drink the juice-syryp in the right.

WHAT? NOT DANGEROUS? Sorry, but I do not think that not drinking the juice-syrup and not taking the pills qualifies as being judiciously cautious. Radium, beryllium and uranium should be absolutely nowhere near a food preparation area. The microscopic amount of radium in paints may not be dangerous externally, but can be extremely harmful if ingested.

I’m not even sure what substance listed I’d consider the most idiotic to cook on your stove – probably 96% sulfuric acid!

But, even if you happen to do things a lot smarter and in a much more controlled manner than Richard Handl or David Hahn, building a fission reactor is a losing proposition.  The biggest problem is the fuel required and the quantity you would need.

Potential Fuels:

Plutonium - Unobtainable to anyone outside of a government agency or a large industrial company.   Plutonium must be produced artificially and then separated from uranium chemically.  It is both very well secured and very expensive.  The only way an ordinary person might be able to obtain a quantity of plutonium would be by tracking down a sample of material that was somehow contaminated with plutonium.   For example, trinitite, a glass produced by the first nuclear weapons test contains microscopic amounts of plutonium.

Such samples contain microscopic levels of plutonium.  Any material which contained more than traces was always sequestered and removed from the site.  Today, these samples are primarily of interest to element collectors, since it is the only legitimate source of plutonium.  The quantity would be far too low for consideration for a nuclear reactor.

Americium-241 -This is the most familiar of all artificially-produced elements as it is the only one available in consumer products.  Ionization smoke detectors use a small amount of Am-241.  Certain industrial equipment may use larger amounts.   Americium-241 is fissile, with the critical mass for a bare sphere of the material being about 60 kg. If Am-241 were used to fuel a reactor where it would be placed in an efficient moderator, substantially less would be needed, possibly as little as a few kilograms.

Such quantities would be impossible to accumulate from sources like smoke detectors, which only contain a fraction of a microgram per unit. In fact, it would take more than a billion smoke detectors to acquire enough Am-241 to create a nuclear chain reaction. The amount that could be recovered from a more practical number of smoke detectors (perhaps several thousand) would be nowhere near enough to create a reactor.

Highly Enriched Uranium – Highly enriched uranium, like that used in nuclear weapons, military reactors and some research reactors would allow for creation of a small nuclear reactor with relative easy.  However, it is extremely expensive and very closely guarded.  There is no way that HEU could be obtained by the average person and certainly would not be legal to purchase or own.

Low Enriched Uranium – Low enriched uranium has concentrations of U-235 up to a few percent and is used in most commercial nuclear power reactors.  It is certainly not something the average person could ever purchase.   Although it is not guarded with anywhere near the kind of security that plutonium or HEU is, it is still not something that would ever be legally obtainable in any quantity.

There are some accounts that have circulated about LEU uranium pellets being available outside of the normal supply channels for reactor fuel.  For example, pellets which do not meet quality control standards might be available to employees of fabrication facilities.   Such stories are hard to confirm and the legality of private ownership of LEU is difficult to determine.  However, even if a person could acquire several LEU pellets, this would not help get them very close to building a nuclear reactor.

Even highly efficient moderators, neutron reflectors and other measures were implemented, one would need a minimum of several tons of LEU to achieve critical mass.  Such quantities are not obtainable to any individual.

Uranium-233 – Uranium-233 is the fuel used for thorium cycle reactors.  It is produced from the neutron irradiation of thorium.  Limited stockpiles of U-233 exist and are impossible to obtain of in any quantity, as it is generally regarded as being potentially weapons material.

Thorium is obtainable, and it is possible to generate neutron radiation by combining available alpha radiation emitters and beryllium or even by building a very small fusion reactor.  This seems to be what David Hahn was attempting to do with his small neutron source and thorium.  However, one would never be able to produce enough U-233 for a reactor or even anything close to it.  The neutron flux that is obtainable from a homemade source is trivial and thus would produce only miniscule quantities of U-233.  Even milligram levels of production would be out of the question without a nuclear reactor as a neutron source, and critical mass would require a minimum of more than a thousand kilograms.

Natural Uranium – This is the ONLY material that the average person would have any chance of acquiring and which could be used to build a nuclear reactor.  Uranium can be purchased as a metal or a compound, but very few suppliers exist, and, because it is such a specialty product, it tends to be expensive.  Most uranium used in laboratory chemicals and consumer products is depleted uranium, which would not be usable as reactor fuel on its own.

The most straightforward way of obtaining large quantities of natural uranium would be to extract it oneself from uranium ore.   Uranium ore is readily obtainable and rock containing high concentrations of uranium can be found in locations around the world.  The process of extracting uranium is not terribly complicated and can be demonstrated using readily obtainable materials.   First, the uranium ore is crushed and pulverized then the resulting material is placed in an acid solution.   Even the hydrochloric acid solutions available from hardware stores are sufficiently acidic for this purpose.   Nitric acid will work even better and is obtainable from any chemical supplier.  The acid solution will dissolve the uranium out of the rock while leaving behind the bulk of the rock material, which can be screened out.

There are a few ways of removing the uranium from the acid solution.   The simplest is to just add a base to neutralize the solution, which will cause the uranium to precipitate out.  The result is a mixture of uranium salts.   This material can be further processed by other methods to obtain uranium oxide.   Converting it into uranium metal is more difficult but not impossible.  For use in a reactor, the uranium must be of a very high purity, so regardless of which technique is used, there will have to be a final solvent-solvent extraction step to remove any contaminants from the uranium and produce material pure enough to be used in a nuclear reactor.

The acid extraction method works well with many common ores such as uranite, but will not work with carnotite or other uranium ores that are too alkaline for this method.  An alternative method is to use an alkaline extraction method or various types of solvent extraction.

Basic information on how to preform uranium extraction demonstrations can be found from United Nuclear’s website.   Preparing uranium compounds of relatively high purity is certainly not beyond the capabilities of any advanced amateur with access to uranium ore and the desire to do so.   However, what makes this an unrealistic source of reactor fuel is the sheer amount of uranium that would be required.   Using a small ballmill and laboratory flasks would never be sufficient to produce enough fuel for a reactor.  In fact, doing so would require nothing less than an industrial-scale operation.

How much uranium will be required:

How much natural uranium will be required depends on the moderator being used in the reactor and the design of the reactor.  If natural uranium is the fuel, only the most efficient moderators, with the lowest neutron capture cross-sections will work.   Regular water or “light water” is the most common moderator in nuclear power reactors, but it will not work at all in a reactor fueled by natural uranium.  Only enriched uranium, and many tons of it, can be used with light water.  Natural uranium will require a much more efficient neutron moderator.

The simplest, most easily available and low cost moderator suitable for a natural uranium fueled reactor is graphite.   Not all graphite will work for this purpose.  A good example of a “small” graphite-moderate natural uranium reactor is Chicago Pile-1, which is also the first nuclear reactor ever successfully demonstrated.  CP-1 was designed by Enrico Fermi using calculations from smaller subcritical experiments.   It was intended to be only barely large enough to achieve a sustained chain reaction.   In fact, the reaction was so small that no radiation shield was needed and very little heat was generated.   The only way of even knowing that the reaction was occurring was by the readings on instruments measuring the radiation produced by the reactor.

CP-1 used about forty short tons of natural uranium, in the form of uranium oxide and uranium metal.  It also contained four hundred short tons of graphite, milled into 45,000 blocks. It’s possible that the size could be reduced slightly by making some design changes, such as distributing the uranium in smaller fuel elements, and thus increasing the moderation effect of the graphite, but not by very much.  CP-1 is approximately as small as a graphite-moderated, natural uranium reactor can get.  Still, it weighed hundreds of tons and required a great deal of labor to construct.   The high purity graphite blocks had to be machined to fit perfectly together and construction was laborious.

It is possible to reduce the amount of natural uranium required by using an even more efficient moderator than graphite.   Deuterium oxide, also known as heavy water, is another option for moderating a natural uranium fueled reactor.   It is even more efficient than graphite and therefore requires less uranium to achieve critical mass.  Heavy water is chemically identical to light water, but it has been isotropically separated and contains mostly deuterium, an isotope of hydrogen that occurs in only trace amounts in natural water.  Because of energy and effort required to separate the isotopes, it is very expensive.

According to information from the Oak Ridge National Laboratory, it is theoretically possible to build a natural uranium-fueled reactor, moderated by heavy water and containing as little as about three and a half metric tons of uranium oxide.  However, such a reactor would require a very large amount of heavy water to act as both the coolant and as a neutron reflector.  In total, well over 20 metric tons of heavy water would be required.  It is possible to use less heavy water in a reactor, if larger amounts of natural uranium are used.  For example, CP-3, the first heavy water reactor, used substantially less heavy water but required substantially more natural uranium.  CP-3 only used 6.5 short tons of heavy water – about 7 metric tonnes.

While 3.5 tonnes of natural uranium might seem more reasonable than 40+ tonnes, it’s still a lot of uranium to acquire.  The bigger problem will be the cost of the heavy water.  Heavy water can be purchased from most major chemical suppliers, as it is used as an isotopic tracer and for certain spectrographic applications.   The cost ranges from 300 to 600 US dollars per kilogram wholesale, but is likely to be more if purchased retail by an end user.   Therefore, the heavy water in a reactor would be millions of dollars by itself.   That is not even to mention the cost of the precision, high purity cladding required, the uranium or the construction of the reactor vessel.    Not only is cost a problem, but buying thousands of kilograms of heavy water would put a run on supplies of the material, as it is only used for special applications and rarely would be purchased in such large quantities, except for nuclear reactor use.

Slightly better efficiency and thus smaller fuel requirements could likely be reached through the use of an aqueous homogenous reactor, although this would still require milli0ns of dollars of heavy water and tons of uranium.  Furthermore, the nature of aqueous homogenous reactors necessitates special materials be used to resist corrosion, complicating construction further.

To Sum Up The Fuel Problem:

Plutonium - Unavailable
Highly Enriched Uranium – Unavailable
Low Enrichment Uranium – Difficult to Impossible to get.  Perhaps small samples could be obtained, but nowhere near what is needed
Uranium-233/Thorium Cycle – Unavailable and too high a neutron flux is required to breed it on ones own
Americium-241 – Available, but only in microscopic quantities
Natural Uranium – Available in small quantities.   Large quantities would require refining of ore, which is a major undertaking on a large scale.

Reducing the size necessary:

Unfortunately for would-be reactor builders, there is very little you can do to reduce the size necessary to achieve critical mass.  Using a large neutron reflector, composed of high purity graphite, beryllium or heavy water can help, but only slightly.   Adding a more potent fission fuel, such as Am-241 could also reduce critical mass.  However, since only microgram quantities can be obtained, it would have an insignificant impact.

One approach that was used by both David Hann and Richard Handl was to generate supplemental neutrons in order lower the critical mass needed to keep the reaction going by reducing the need for fission-derived neutrons. The way both tried to do this is by using a homemade mixture of beryllium and radium-226. When beryllium is bombarded by alpha particles, it will occasionally absorb an alpha particle and undergo fusion, releasing neutrons in the process. It seems both chose radium-226 as their alpha source because it’s readily available in the form of antique luminescent paint.  (Technically, one could argue that the use of beryllium-derived neutrons makes it a “subcritical reactor”)

The problem with this approach is that it just does not produce enough neutrons to make a difference in a nuclear reactor.   For every million alpha particles that strike beryllium, only thirty neutrons will be produced.  Homemade neutron sources can be produced by combining americium or radium with beryllium (NOTE: This is not recommended or condoned) but the neutron flux will be extremely low.  It will have no significant effect on the amount of uranium required for a reactor to actually function.

Conclusion:

Those who have tried to build fission reactors in their homes generally seem oblivious to what is actually required and commonly engage in extremely unsafe activities.  The reality is that a nuclear fission reactor requires either materials that are entirely unavailable to the individual or many tons of expensive natural uranium and high quality graphite or heavy water.  The size is irreducible because critical mass must be achieved.


This entry was posted on Sunday, June 16th, 2013 at 9:15 pm and is filed under Bad Science, Misc, Not Even Wrong, Nuclear. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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42 Responses to “Why You Cannot Build a Nuclear (Fission) Reactor At home”

  1. 1
    DV82XL Says:

    A heavy water aqueous homogeneous reactor might achieve criticality with natural uranium dissolved as uranium sulfate apparently with only a few kilos of fuel if the reactor vessel is made of a good neutron reflector like beryllium or tungsten carbide – at least in theory.


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  2. 2
    drbuzz0 Says:

            DV82XL said:

    A heavy water aqueous homogeneous reactor might achieve criticality with natural uranium dissolved as uranium sulfate apparently with only a few kilos of fuel if the reactor vessel is made of a good neutron reflector like beryllium or tungsten carbide – at least in theory.

    I’ve read that heavy water aqueous homogenous reactors can achieve much lower critical mass. In principle, they would need to have a very very good reflector and a near perfect design, with good circulation to keep the fuel very uniformly dissolved and high grade materials.

    Near as I can tell, while that may be theoretically possible, nobody has ever made it work with anything less than a few hundred kilos of natural uranium.


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  3. 3
    Jason J Says:

            DV82XL said:

    A heavy water aqueous homogeneous reactor might achieve criticality with natural uranium dissolved as uranium sulfate apparently with only a few kilos of fuel if the reactor vessel is made of a good neutron reflector like beryllium or tungsten carbide – at least in theory.

    Um… maybe, but that still might be beyond the capabilities of an amateur working alone.

    Sounds like a bare minimum of tens of thousands of dollars of heacy water.

    And that is forgetting about the tolerances and having materials that are proper and keeping everything pure enough.

    BTW: The exploding acid on the guy’s dirty kitchen stove is epic. What the **** was he thinking?


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  4. 4
    DV82XL Says:

            drbuzz0 said:

    In principle, they would need to have a very very good reflector and a near perfect design, with good circulation to keep the fuel very uniformly dissolved and high grade materials.

    Yes, and such a task is well outside the casual DIY envelope for any number of reasons, but if someone, or a small group, was set on making a fission reactor an AHR would give them the best shot. It wouldn’t be easy, but I think it’s doable.


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  5. 5
    Anon Says:

    If you try to buy tonnes of heavy water it’s likely that people will start asking question of you and they may not be very comfortable ones.

    I wonder if seawater extraction of Uranium would be doable by small groups.

    An AHR if you can get the heavy water does seem like it’d be the way to go for a small group and hope no one figures out what the strange alloys they’d buy will be used for.

    In some ways I’d say the fact that individuals can’t build their own reactors is a bit sad, if it were possible we’d have a nice easy way around the anti-nuclear movement.


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  6. 6
    Matte Says:

    I may get myself into some serious problems here…but what about building a small scale Farnsworth Fusor or polywell and mantle it with uranium? Think about it?! Pu from electricity (and lots of time)…


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  7. 7
    DV82XL Says:

    Apparently Israeli nuclear designers have designed small homogeneous reactors based on americium that requires only 0.7 kg of fuel. This reactor is estimated to weigh 4.95 kg and the radius of the reactor case is 9.6 cm.

    Now mind you as the lead article states, collecting even 700g of this material from readily available sources is next to impossible but americium is also used as a neutron source in industrial gauges. While these are usually licenced and closely tracked in most countries, as we have seen with medical sources like cobalt, things are far more relaxed in the Third World.


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  8. 8
    I'mnotreallyhere Says:

    All this just reminds me of the brilliant reviews for the Uranium ore samples you can order from Amazon.

    For anyone who’s forgotten : http://www.amazon.com/gp/product/B000796XXM/ref=cm_cr_dpvoterdr#R3JUIEGFUTUWMI.2115.Helpful.Reviews


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  9. 9
    Ray Says:

            DV82XL said:

    Apparently Israeli nuclear designers have designed small homogeneous reactors based on americium that requires only 0.7 kg of fuel. This reactor is estimated to weigh 4.95 kg and the radius of the reactor case is 9.6 cm.

    Now mind you as the lead article states, collecting even 700g of this material from readily available sources is next to impossible but americium is also used as a neutron source in industrial gauges. While these are usually licenced and closely tracked in most countries, as we have seen with medical sources like cobalt, things are far more relaxed in the Third World.

    Still not likely, I would think.

    A home smoke detector uses about 1-20 microcurries of Am-241. Industrial ones can use 50-100. Moisture gauges and other test equipment can be 50 millicuries.

    The largest sources of Am-241 you are ever likely to find are 1-3 curie well logging or soil probe neutron sources. Note that there are not a lot of these floating around. You’d be lucky to get your hands on a few of them.

    Am-241 is 3.4 curies per gram.

    Do the math. The largest you can get is less than one gram, but that is rare and atypical. Most will be less. And mind you, regardless of regulations, it’s not like 3 curie well logging sources are being discarded left and right without concern, because they are damn expensive too


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  10. 10
    DV82XL Says:

    Oh well, there goes my plans for a personal reactor.


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  11. 11
    drbuzz0 Says:

            Matte said:

    I may get myself into some serious problems here…but what about building a small scale Farnsworth Fusor or polywell and mantle it with uranium? Think about it?! Pu from electricity (and lots of time)…

    That could be done (and I believe Fusor builders have even experimented with neutron irradiation of uranium) but it would not get you anywhere.

    The neutron flux of an amateur Fusor is very low. No fusion reactor, short of the largest tokomak’s produces anywhere near the neutron flux of a fission reactor. If you expose uranium to that neutron flux you will get a tiny bit of fission and produce a tiny bit of plutonium, but not much at all. I doubt you could make a milligram even if you ran it continuously for years.

    In the early days of nuclear weapon production, one option for producing plutonium and/or uranium-233 was to use large accelerators to produce neutrons. It’s the same basic idea as using a fusor. Actually, a fusor is really an accelerator-driven fusion system. This option was investigated, but they came to the conclusion that it was a terribly inefficient way of doing it. Thus it was abandoned. It would be huge, use lots of electricity and have a tiny amount of production.

    The idea of a “subcritical reactor” has been proposed many times as well. Basically it would be a reactor that did not quite reach critical mass, but kept going because supplemental neutrons are provided by a neutron source (fusion, spallation etc). The problem with this is that for these reactors to be stable and produce energy, it seems they have to run very very close to their critical mass, which basically defeats the purpose.

    Producing neutrons via accelerator-driven fusion is highly inefficient. The majority of energy is lost driving the system.

    About the only thing that producing plutonium with a Farnsworth Fusor would be good for would be as a classroom demonstration or something like that. With a large enough Fusor, you could probably produce enough plutonium that it would be detectable, at least by sophisticated enough spectroscopy. The practical amount still is going to be microscopic.


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  12. 12
    drbuzz0 Says:

    BTW: I think of all the plans for a personal reactor, the most realistic one is the heavy water AHR, using uranium sulfate and some high grade materials along with a reflector.

    Still… not easy by any means. You’ll need quite a bit of heavy water and a fair amount of uranium, which would need to be in the sulfate form and very pure and well prepared.

    A bit issue with sulfate AHR’s has been corrosion. You’d need to find some special materials that were resistant to that kind of corrosion and would not contaminate the mixture and they would also have to be very neutron-transparent to allow the neutrons to pass through to reflect off the neutron reflectors.

    There are some other issues with AHR’s, which are not insurmountable to professional environments, but can be a problem for someone working in their garage. They tend to produce hydrogen through dissociation of hydrogen from water and this can be an issue for safety and because the bubbles can reduce moderation. They need systems to collect the hydrogen safety. The fission byproducts need to be removed (the fact that this can be done is a feature, but it does need to be done for ones that are running with low neutron economy)

    The mixture must be controlled very precisely and be very uniform.

    These are not a huge problem to a professional nuclear laboratory. They might be an issue for a Swedish dude working in the kitchen of his apartment, or an American boyscout in his mom’s potting shed.


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  13. 13
    Anon Says:

            DV82XL said:

    Apparently Israeli nuclear designers have designed small homogeneous reactors based on americium that requires only 0.7 kg of fuel. This reactor is estimated to weigh 4.95 kg and the radius of the reactor case is 9.6 cm.

    That would use a different isotope (242m to be precise) which is not at all easy to get (it won’t last long in a reactor).

    Main promise with that would be in fission fragment rockets where it could be very nice, probably too expensive to make for any other use (assuming we can figure out a way to make it in quantity and it has a low enough thermal neutron critical mass).


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  14. 14
    DV82XL Says:

            drbuzz0 said:

    There are some other issues with AHR’s, which are not insurmountable to professional environments, but can be a problem for someone working in their garage. They tend to produce hydrogen through dissociation of hydrogen from water and this can be an issue for safety and because the bubbles can reduce moderation. They need systems to collect the hydrogen safety.

    They produce both hydrogen and oxygen together and in all designs this is recombined on a platinum wool catalytic column. Corrosion is the big issue though, and is one of the big reasons development on this type is stalled in the West.

    Techniques of radioactive isotope production are being developed at the Kurchatov Institute in Russia on an AHR called the ARGUS reactor. This reactor, with 20 kW thermal output power. Its core volume is 22 liters of UO2SO4 solution containing. 1.71kg of 90% enriched uranium. The reactor has been in operation since 1981 and it is claimed to have shown high indices of efficiency and safety. Feasibility studies to develop techniques for strontium-89 and molybdenum-99 production and conversion to LEU are still underway. However recent success producing these isotopes in commercial quantities with particle accelerators may make this technology redundant.


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  15. 15
    Q Says:

            DV82XL said:

    They produce both hydrogen and oxygen together and in all designs this is recombined on a platinum wool catalytic column. Corrosion is the big issue though, and is one of the big reasons development on this type is stalled in the West.

    Techniques of radioactive isotope production are being developed at the Kurchatov Institute in Russia on an AHR called the ARGUS reactor. This reactor, with 20 kW thermal output power. Its core volume is 22 liters of UO2SO4 solution containing. 1.71kg of 90% enriched uranium. The reactor has been in operation since 1981 and it is claimed to have shown high indices of efficiency and safety. Feasibility studies to develop techniques for strontium-89 and molybdenum-99 production and conversion to LEU are still underway. However recent success producing these isotopes in commercial quantities with particle accelerators may make this technology redundant.

    BUT…

    Can you build it in your kitchen or garage?

    I think that is the crux of the argument here.


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  16. 16
    Shafe Says:

            Q said:

    BUT…

    Can you build it in your kitchen or garage?

    No, that would be silly. The garage is best suited to fusion reactors, and experimentation in the kitchen has proven to be a contamination hazard for the heart meds you keep on the back burner.

    The tool shed is the place. There are buckets there and a paint mixer for preparing the solution. And dust masks in case there is a containment failure.


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  17. 17
    Ray Says:

    Did not mention, but reading this I am taken by the weapons grade stupidity of Richard Handl.

    David Hahn’s experiments were not advisable either, but he was a teenager, so you expect stupid things to be done, and as far as stupid things teenagers do, at least what he did had a lot more ambition and was more interesting.

    An adult “cooking” radium paint, smoke detector sources and beryllium in glassware filled with acid on his kitchen stove absolutely boggles my mind… then he declares it’s “not dangerous” as if that was not enough…


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  18. 18
    DV82XL Says:

            Q said:

    BUT…

    Can you build it in your kitchen or garage?

    I think that is the crux of the argument here.

    One would have to make a number of assumptions concerning the availability of HEU on some black market given 1.71kg is not that huge an amount, and to the best of my knowledge there has been no credible instances where HEU has been trafficked that way. Other than that it wouldn’t be that technically difficult to get a crude AHR to go critical, indeed there have been a few occasions where such a reactor has been made accidentally, in one case in an 80 gal steel drum. The resulting excursion was energetic enough to roast the poor devil who did it with enough radiation that he died a few hours after.


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  19. 19
    Anon Says:

    AHRs can get a breeding ratio greater than one (even in light water form) so once you got it started you could keep it going just on DU and even make more fuel to start up other reactors.


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  20. 20
    Matte Says:

            drbuzz0 said:

    With a large enough Fusor, you could probably produce enough plutonium that it would be detectable, at least by sophisticated enough spectroscopy.

    The practical amount still is going to be microscopic.

    You are most likely correct. Unless if it is true that the power output of the fusor increases with the 5th power of the radious. Scaling may be a bit of an issue for the average garage builder but it is an interesting thought, no?


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  21. 21
    drbuzz0 Says:

            Matte said:

    You are most likely correct. Unless if it is true that the power output of the fusor increases with the 5th power of the radious. Scaling may be a bit of an issue for the average garage builder but it is an interesting thought, no?

    I’m really not an expert on this, but my understanding of the fusor is that it does not necessarily scale well to large sizes. Most of the fusors built have been pretty small, and as you get larger and larger, it becomes harder to make it work. The grid in the center becomes larger and there’s more space for the ions to miss each other. You need much higher voltage to accelerate them etc. Higher voltages increase collisions with the grid and degradation.

    There are some variations on electrostatic confinement fusion that can be scaled much larger. For example, the Polywell reactor can apparently be scaled to much larger sizes. It’s been claimed that the polywell could be energy producing if it were large enough, but again, I’m no expert.

    Producing plutonium is certainly possible with a very large fusion reactor, such as the largest tokomaks. Some have even said it’s a proliferation hazard, but if you make your plutonium that way, you’re doing it the difficult and expensive way.


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  22. 22
    Ray Says:

            DV82XL said:

    One would have to make a number of assumptions concerning the availability of HEU on some black market given 1.71kg is not that huge an amount, and to the best of my knowledge there has been no credible instances where HEU has been trafficked that way. Other than that it wouldn’t be that technically difficult to get a crude AHR to go critical, indeed there have been a few occasions where such a reactor has been made accidentally, in one case in an 80 gal steel drum. The resulting excursion was energetic enough to roast the poor devil who did it with enough radiation that he died a few hours after.

            Anon said:

    AHRs can get a breeding ratio greater than one (even in light water form) so once you got it started you could keep it going just on DU and even make more fuel to start up other reactors.

    The point we keep coming back to is that you can pretty easily build a reactor if you can get a significant amount of highly enriched uranium or plutonium or something else fissionable.

    Of course, that’s true. It can even happen by accident.

    The question is whether someone like Handl or Hahn, working as an ambitious amateur but only having access to things freely available at hardware stores, chemical suppliers, yard sales and eBay.

    You can’t do it. Unless you happen to cross paths with some Russian Mafia member who will sell you HEU, likely for millions of dollars. If that should happen, you will probably have bigger problems on your hands, like, for example, if you blog about it, you’ll end up in deeper trouble than you can imagine.

    In any case, even considering that would clearly be a rare and very exceptional circumstance.

    That brings us back to the main point which is that the only materiel workable in a reactor that the average person MIGHT be able to get is natural uranium, which needs quantities so large as to be unworkable, not to mention the need for massive amounts of high grade graphite or heavy water.

    AHR’s are not going to be much easier for Joe Schmo in his apartment kitchen.


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  23. 23
    Anon Says:

            Ray said:

    The point we keep coming back to is that you can pretty easily build a reactor if you can get a significant amount of highly enriched uranium or plutonium or something else fissionable.
    [...]
    The question is whether someone like Handl or Hahn, working as an ambitious amateur but only having access to things freely available at hardware stores, chemical suppliers, yard sales and eBay.

    How close could someone come though? Probably not an individual (unless very wealthy).

            Ray said:

    You can’t do it. Unless you happen to cross paths with some Russian Mafia member who will sell you HEU, likely for millions of dollars. If that should happen, you will probably have bigger problems on your hands, like, for example, if you blog about it, you’ll end up in deeper trouble than you can imagine.

    Plutonium and HEU on the black market would be a law enforcement sting (and the Russian mob is rather closely connected with the state security apparatus).

            Ray said:

    That brings us back to the main point which is that the only materiel workable in a reactor that the average person MIGHT be able to get is natural uranium, which needs quantities so large as to be unworkable, not to mention the need for massive amounts of high grade graphite or heavy water.

    Yes, seawater extraction would seem to be the way to go to get that U, moderator material is likely to be a bigger problem.


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  24. 24
    drbuzz0 Says:

            Anon said:

    Yes, seawater extraction would seem to be the way to go to get that U, moderator material is likely to be a bigger problem.

    Really?

    Seawater extraction isn’t currently economical on an industrial scale. I can’t imagine an amateur pulling significant uranium from sea water.

    Last I heard the best method yet developed was a Japanese technology that used enormous mats made of chemically-impregnated fibers. They would be left to soak in sea water for months and then brought back to extract uranium. They were estimating a few thousand dollars per kilogram.


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  25. 25
    Anon Says:

    Last I heard was that the cost would be low enough to still be economical even if it couldn’t compete with conventional mining.

    Main advantage I could see would be that such a process could be less labour intensive than conventional mining (or maybe in situ leeching would be the way to go).


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  26. 26
    Ray Says:

    If you want to produce uranium in your backyard or garage, I think ocean extraction is going to be a problem. First off, you need to be near the ocean, which I guess would not be a problem for everyone, but would be one if you lived in Kansas.

    The problem is that while the technique is straight forward enough, the materials and scale necessary preclude amateurs. The Japanese developed a process of soaking large amounts of chemically treated fibers in the ocean. These become coated with uranium. Then material is pulled from the ocean and brought to a facility where it is washed with chemicals to free the uranium.

    The resulting solution contains high concentrations of urnanium, but also everything else in the sea (calcium, magnesium, potassium, sodium, chloride, little bits of seaweed) As a result it must go through a process of purification and concentration.

    The problem is the amount of uranium in the sea is low and so the process must be big to get any. You can’t do this in your bathtub. You will get nowhere.

    A hundred kilos of uranium means hundreds of tons of absorbers to soak and process. Maybe economical on an industrial level, but certainly not in your kitchen.

    IF an amateur wanted the best shot at making some uranium from natural sources, I am sure the best option would be to obtain uranium ore of the highest grade possible. There is some uranium ore that is so high grade, when you look at it, it does not look like rock but solid black uranium oxide. It’s the densest type of uranite pitchblende. It is rare, unfortunately. Veins of such high grade uranium are known to be found in Canada and Australia and elsewhere, but few and far between and the near surface ones have been mined.

    They sometimes pull big chunks of uranium out of Great Bear Lake in Canada, but that whole area is now a private uranium mine, so you can’t just walk in.

    There is one place in the world known for having large amounts of ultra high grade uranium in nature. Large deposits of super grade uranium are found in Congo. This is where Marie Curie got her pitchblende and it’s where some of the earliest harvesting of uranium for radium production was done.

    Again, large, near surface deposits located near civilization are either being mined or were mined to exhaustion. If you want to find large amounts of this grade of uranite, be prepared to trek into the jungle.


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  27. 27
    Ray Says:

    One other thing nobody has mentioned that could be a deal killer: If you process uranium or with acid or alkaline extraction, you get uranium concentrate. This is only the first step in the nuclear fuel production process.

    Uranium for reactor use (especially if you want to use natural uranium) would have to be very pure. The concentrate of uranium salts that comes from the ore processing is not nearly pure enough. Uranium always occurs with other material, even in the highest grade deposits, because it produces daughter products. Also, commonly has magnesium, bismuth, phosphorus, copper etc etc.

    You need to get this out, especially some of the minor constituents which, even at trace levels, have high neutron cross sections. In practice this means multiple steps of selective solvent extraction or electrorefining.

    Possible on a laboratory scale, but difficult for an amateur to do at a rate that will produce a reactor core quantity of fuel.


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  28. 28
    Anon Says:

            Ray said:

    They sometimes pull big chunks of uranium out of Great Bear Lake in Canada, but that whole area is now a private uranium mine, so you can’t just walk in.

    Somehow I doubt they bother much with security over much of the area (and given that building your own nuclear reactor is almost certainly illegal if you’re going to do that you probably won’t care about trespass), of course serious mining would probably require more equipment than a trespasser could bring in.


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  29. 29
    Robert Sneddon Says:

    The estimate I saw for the Japanese experimental seawater extraction method was about $300 per kilo of uranium although they didn’t say if this was the cost of producing the metal or of an oxide like UO2 or U3O8. Spot price of yellowcake from various mines around the world is about $90 per kilo at the moment.

    However the experimenters were working in the fast Kuroshio current which runs close to the shore of Honshu, an advantage many coastal areas elsewhere don’t have, which allowed their mat collectors to be swept by a lot of seawater per day. Other coastal areas with lesser currents would probably need pumps etc. to optimise the utility of the fibre deposition systems.


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  30. 30
    I'mnotreallyhere Says:

            Robert Sneddon said:

    The estimate I saw for the Japanese experimental seawater extraction method was about $300 per kilo of uranium although they didn’t say if this was the cost of producing the metal or of an oxide like UO2 or U3O8. Spot price of yellowcake from various mines around the world is about $90 per kilo at the moment.

    However the experimenters were working in the fast Kuroshio current which runs close to the shore of Honshu, an advantage many coastal areas elsewhere don’t have, which allowed their mat collectors to be swept by a lot of seawater per day. Other coastal areas with lesser currents would probably need pumps etc. to optimise the utility of the fibre deposition systems.

    The price is pretty meaningless without a scale too. It’s one thing to hit $300/kg for an annual production of a million tonnes (random figure, not at all accurate) but tooling up just to produce 3kg is going to cost a LOT more than $300/kg.


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  31. 31
    Robert Sneddon Says:

    The researchers calculated a sheaf of costs based on different operational cycles — leaving the mats in the current to collect more uranium versus more rapid cycling of the collectors, wear and tear of the mats and lower absorption rates after multiple uses etc. and guesstimated the cost of plant, operations etc. Their ballpark figures suggested the capital costs for a 1200 tonne/year installation, recovering enough uranium to keep six 1GW reactors running would be about $100 million with an operational cost of about $250 per kilo of uranium metal.

    These are research figures though, not forecasts by a company making plans to build and operate such an extraction plant.


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  32. 32
    drbuzz0 Says:

            Anon said:

    Somehow I doubt they bother much with security over much of the area (and given that building your own nuclear reactor is almost certainly illegal if you’re going to do that you probably won’t care about trespass), of course serious mining would probably require more equipment than a trespasser could bring in.

    That may be, but aside from being one of the world’s richest uranium deposits, Great Bear Lake is way the hell up in the northern part of the Northwest Territories of Canada. There are a couple uranium mines there that were closed for lack of any way to get the ore out. They were bringing in equipment via ice road in the winter. There was a very rich mine at Port Radium, but they closed it for lack of any way to get the ore out other than by small aircraft, which was not exactly economical.

    Some of these areas do have very rich deposits, but the only way to get there would be to trek up to Yellowknife and then charter yourself a float plane.

    I suppose that’s not a lot worse than going into the deep Congo.


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  33. 33
    hadr0n Says:

    If Ron Paul became president, wouldn’t we all be able to run our own reactors? ;)


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  34. 34
    DV82XL Says:

            Anon said:

    Somehow I doubt they bother much with security over much of the area

    You might be surprised. The area is patrolled by the Canadian Rangers an almost all native sub-component of the Canadian Forces reserve’s Joint Task Force (North) The area might look like uncharted wilderness to us, but to those guys, who patrol while serving their trap-lines, it’s like your backyard is to you. They also train other elements of the Canadian Armed Forces in such disciplines as wilderness survival using training publications with ominous titles like “Dig or Die.”


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  35. 35
    Anon Says:

            DV82XL said:

    You might be surprised. The area is patrolled by the Canadian Rangers an almost all native sub-component of the Canadian Forces reserve’s Joint Task Force (North) The area might look like uncharted wilderness to us, but to those guys, who patrol while serving their trap-lines, it’s like your backyard is to you. They also train other elements of the Canadian Armed Forces in such disciplines as wilderness survival using training publications with ominous titles like “Dig or Die.”

    Any permanent operation wouldn’t be able to last undetected so it’d be limited to sneaking in, digging some stuff up and getting it out, then leaving, doubt you could get much that way.


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  36. 36
    DV82XL Says:

            Anon said:

    Any permanent operation wouldn’t be able to last undetected so it’d be limited to sneaking in, digging some stuff up and getting it out, then leaving, doubt you could get much that way.

    I don’t even think you could get away with that. I have spent some time North of 60 and it is place where not much goes unnoticed. To start off with there are a limited number of points of entry, and you have to use them as there isn’t an aircraft that can reach any given point up there from the South that wouldn’t light up the rather fine-grained radar monitoring the area gets by NORAD. If you do go in by a regular route everyone will be aware – there is a surprisingly efficient ‘jungle telegraph’ (irony unintended) that spreads news over a vast area with shocking speed.


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  37. 37
    Neil Craig Says:

    So Sheldon could have done it.


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  38. 38
    TZ Says:

    Somebody try the design of a vibratory – vacuum distillation molten UF4 equipment?


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  39. 39
    Glenn Says:

    I’m a bit late to the discussion here, but I found it quite fascinating. It seems clear building a reactor would be extremely difficult to say the least, but I’ve never understood why a home built nuclear battery couldn’t be constructed (think Henry Moseley’s work). The size and power output would be impractical I’m sure, but it would make for an interesting DIY project/demonstration. I’m thinking something like a beta/alpha cell that might charge a capacitor over time to produce a small, periodic burst of power. Any thoughts/links/information you can share? Has this been done before?


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  40. 40
    Anon Says:

            Glenn said:

    I’m a bit late to the discussion here, but I found it quite fascinating. It seems clear building a reactor would be extremely difficult to say the least, but I’ve never understood why a home built nuclear battery couldn’t be constructed (think Henry Moseley’s work). The size and power output would be impractical I’m sure, but it would make for an interesting DIY project/demonstration. I’m thinking something like a beta/alpha cell that might charge a capacitor over time to produce a small, periodic burst of power. Any thoughts/links/information you can share? Has this been done before?

    You might have a hard time obtaining the material needed, ²⁴¹Am would be a workable α emitter and maybe you could do a small demonstration using taken apart smoke detectors (disclaimer: I don’t endorse taking apart smoke detectors).

    Thermal conversion of course isn’t going to work with such small samples so you’ll probably have to directly use the charged particles.


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  41. 41
    Glenn Says:

            Anon said:

    You might have a hard time obtaining the material needed, ²⁴¹Am would be a workable α emitter and maybe you could do a small demonstration using taken apart smoke detectors (disclaimer: I don’t endorse taking apart smoke detectors).

    Thermal conversion of course isn’t going to work with such small samples so you’ll probably have to directly use the charged particles.

    Is there some reason ²⁴¹Am would be necessary versus, for example, using a thoriated welding rod which would also give off alpha particles? The energy density in a welding rod would be much less, but also much safer to handle and a large quantity could easily be obtained. Is a certain decay energy required for that charge separation to occur?


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  42. 42
    Anon Says:

            Glenn said:

    Is there some reason ²⁴¹Am would be necessary versus, for example, using a thoriated welding rod which would also give off alpha particles? The energy density in a welding rod would be much less, but also much safer to handle and a large quantity could easily be obtained. Is a certain decay energy required for that charge separation to occur?

    ²⁴¹Am is considered to be one of the better materials for an RTG so would probably also do better at other ways of turning radiation into energy.

    Though you could get a small current from an α from Th and welding rods are easier to get, whether it’d be enough?


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