New Small Fission Reactor For Deep-space Missions Demonstrated

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New Small Fission Reactor For Deep-space Missions Demonstrated

Posted by samzenpus on Thursday November 29, 2012 @03:07PM from the in-space-nobody-can-hear-you-split-an-atom dept.

cylonlover writes "Exploring the regions of deep space beyond Mars means sending probes where solar power isn't practical. Since the 1960s, NASA has equipped its Apollo missions and unmanned explorers with Radioisotope Thermal Generators (RTGs). These have worked very well, but they run on plutonium 238, which is currently in short supply. Therefore, the Los Alamos National Laboratory is developing a new small nuclear reactor for spacecraft that uses uranium instead of plutonium to power Stirling engines and generate electricity. At the Nevada National Security Site's Device Assembly Facility near Las Vegas, engineers from Los Alamos, the NASA Glenn Research Center and National Security Technologies LLC conducted a Demonstration Using Flattop Fissions (DUFF) experiment that produced 24 watts of electricity using a pair of free-piston Stirling engines."

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What could possibly go wrong by Anonymous Coward · 2012-11-29 15:15 · Score: 0

launching a critical mass of U235 on a rocket.
1. Re:What could possibly go wrong by Anonymous Coward · 2012-11-29 15:25 · Score: 0
  
  Are you serious? This isn't dangerous at all.
2. Re:What could possibly go wrong by Nostromo21 · 2012-11-29 15:26 · Score: 1, Funny
  
  I love the smell of nu-cu-lar power in the morning!
  http://www.youtube.com/watch?v=hORaebYWDwk
  Critical mass of U235 is around 52kg (100lbs), so just keep two halves as far away from each other as possible i.e. opposite ends of the ship.
  Of course, even a fizzout isn't going to be real pleasant in space, but hey, at least half the crew still have a chance of crash landing on Mars! :)
3. Re:What could possibly go wrong by cbhacking · 2012-11-29 15:39 · Score: 4, Informative
  
  Only critical if combined. If the rocket breaks apart or the engines explode, the core would fall apart; it lacks the explosives necessary to bring the Uranium to super-criticality. Worst likely case would be that the control rod gets jammed but the housing stays intact, but the cooling system is destroyed, leaving the core at critical and causing a meltdown. The odds of that seem extremely low, though.
  It'd be a very nasty "dirty bomb" if it blew up in the atmosphere, but no more than that, and a slug of Plutonium hot enough to run a spacecraft for a few years or even decades is a nasty thing to blow up in the atmosphere too. We've been launching those for decades, though.
  
  --
  There's no place I could be, since I've found Serenity...
4. Re:What could possibly go wrong by Whatsisname · 2012-11-29 16:20 · Score: 5, Insightful
  
  It's wouldn't be objectively any nastier than the other toxic substances such as hydrazine that would be sprayed all over the place in an explosion. "Dirty bombs" are not something to be taken seriously. Blowing up an equal mass of mercury would be more dangerous than the uranium, and the damage uranium would pose is more that it is a heavy metal than due to it being radioactive.
5. Re:What could possibly go wrong by LordLucless · 2012-11-29 16:28 · Score: 4, Insightful
  
  "Dirty bombs" are a true terrorism weapon - they cause far more terror than is actually justified, just like the 9/11 attacks did for air travel. Radiation is all scary and mysterious and dangerous and Chernobyl and Fukushima and OMG we're all gonna die!
  That's their purpose, more than actually causing fatalities.
  
  --
  Just because you're paranoid doesn't mean there isn't an invisible demon about to eat your face
6. Re:What could possibly go wrong by DNS-and-BIND · 2012-11-29 16:46 · Score: 1
  
  Yes, lots of people protested NASA's risky space launch of a nuclear reactor but failed to stop the launch. The cops treated them just like they treated OWS. Sigh.
  
  --
  Shutting down free speech with violence isn't fighting fascism. It IS fascism!
7. Re:What could possibly go wrong by Anonymous Coward · 2012-11-29 17:10 · Score: 0, Informative
  
  No, the boron in the control rod stops the reaction when inserted. If the control rod comes out then you would have a critical mass. I assume that thermal expansion of the core gives this a negative coefficient reactivity which probably makes it safe. This still seems somehow more problematic than launching an RTG with a sub critical mass of Pu.
8. Re:What could possibly go wrong by Sussurros · 2012-11-29 17:37 · Score: 5, Interesting
  
  My father was is the first lot of troops into Nagasaki and he stayed there for as part of the Japanese Occupation Force. They were given no warnings about radiation, no protective equipment, and allowed to pick and pry wherever they wanted among the ruins. HIs photos were taken from pretty much every part of the city.
  
  He had no health problems that could be attributed to radiation. Those of his friends and shipmates who were there also were the same. In every case when they suffered serious ill health it was due to smoking or drinking.
  
  What I have noticed though is curious congenital conditions occasionally popping up in their children, about 1 child in 4 or 5, when there was no history of it previously. This may or may not be coincidence but while these conditions may be awkward for those that have them, no-one has died from one yet.
  
  I myself have worked with radioactive materiels and while they creep the bejesus out of anyone who has anything to do with them the radiation is not overly dangerous at low levels except over long periods, say taking x-rays every day. Even spending six months in Nagasaki starting two weeks after they dropped a plutonium bomb on it didn't cause any problems among the people I know who did it.
  
  --
  I said - don't look Ethel!..., but it was too late..., she'd already looked.
9. Re:What could possibly go wrong by Anonymous Coward · 2012-11-29 17:59 · Score: 0
  
  "It'd be a very nasty "dirty bomb" if it blew up in the atmosphere,"...
  not even, I think. If the reactor isn't operational until it's left the atmosphere (no reentry possible, that is), then it's just a bunch of uranium metal with no radioactive fission daughter nucleids. Uranium metal is problematic (see DU uranium weapons toxicity), but it's not anywhere near a dirty bomb problem.
10. Re:What could possibly go wrong by cyn1c77 · 2012-11-29 18:30 · Score: 3, Informative
  
  No, the boron in the control rod stops the reaction when inserted. If the control rod comes out then you would have a critical mass. I assume that thermal expansion of the core gives this a negative coefficient reactivity which probably makes it safe. This still seems somehow more problematic than launching an RTG with a sub critical mass of Pu.
  Removing the control rod starts the reaction, but it is a sub-critical mass so there is no explosion.
  Just because it is enriched Uranium doesn't mean that it is enriched to weapons grade.
11. Re:What could possibly go wrong by Sussurros · 2012-11-29 18:48 · Score: 2
  
  No, that's the bean burritos.
  
  --
  I said - don't look Ethel!..., but it was too late..., she'd already looked.
12. Re:What could possibly go wrong by bickerdyke · 2012-11-29 20:36 · Score: 1
  
  Wouldn't Hydarzine mustle just burn in an explosion?
  
  --
  bickerdyke
13. Re:What could possibly go wrong by Anonymous Coward · 2012-11-29 21:11 · Score: 1
  
  Nagasaki wasn't a dirty bomb.
  It was a atomic explosion from a nuclear weapon, and relatively clean as a result. A dirty bomb is a conventional explosive with radioactive material mixed in - small blast covering everything nearby in radioactive dust.
  But the risk is relatively small - unless you're near the blast you'll have no problems. If you're nearby and not hurt by the conventional blast itself as long as you get a shower and destroy your clothing quickly you'll probably be just fine.
  The real problem is how to get rid of the dust that's then covering everything. Avoiding the area until it's been washed away is a start, but it'll be blown around a bit too.
14. Re:What could possibly go wrong by AmiMoJo · 2012-11-29 22:43 · Score: 2
  
  Strange because the majority of Japanese casualties, let along people who just got sick, were from radiation in the fallout rather than the blast itself.
  
  --
  const int one = 65536; (Silvermoon, Texture.cs)
  SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
15. Re:What could possibly go wrong by Anonymous Coward · 2012-11-29 22:58 · Score: 1
  
  I hate to be the one to break this to you, but if the core cannot be supercritical, then it cannot reach self-sustaining criticality. What actually keeps it from exploding is fuel dispersion.
16. Re:What could possibly go wrong by tp1024 · 2012-11-29 23:31 · Score: 2
  
  There is no heat that could cause a meltdown in the first place. The reactor will not have run for any significant amount of time at any significant enough power level to release enough heat to melt anything that isn't made of butter ... and even that might be a close call that depends on outside temperatures.
  The fuel rods will consist mostly of U-235, which is much less radioactive than the Pu-238 that is commonly used and doesn't release any heat by itself. The radioactivity only comes into play once the reactor has been started up. But hopefully that will only happen after the probe is on its way away from earth.
17. Re:What could possibly go wrong by Anonymous Coward · 2012-11-30 00:42 · Score: 1
  
  The soldiers probably ate food and water brought from other areas, lessening the chances of ingesting those hot particles. The locals likely weren't so lucky.
18. Re:What could possibly go wrong by kyrsjo · 2012-11-30 00:52 · Score: 1
  
  The radiation from the blast itself and just after it can be very intense, much more intense than from the fallout.
19. Re:What could possibly go wrong by jonnythan · 2012-11-30 01:27 · Score: 1, Interesting
  
  How do you get a sustained fission reaction without critical mass? Critical mass is defined as the mass required to sustain fission.
20. Re:What could possibly go wrong by Anonymous Coward · 2012-11-30 02:56 · Score: 0
  
  I believe the causalities you are referring to are what is sometimes referred to as "the walking dead", people who were close enough to the blast to get a nasty dosage of direct radiation from the flash but far enough away to survive the heat & concussion. Sadly they are already dead, their bodies just haven't realized it yet. The radiation flash from I believe the first 10-30 seconds of the blast has already fried their DNA, and while they may feel fine for a while, as time goes on and their body's are no longer able to produce healthy blood and tissue cells they slowly waste away.
21. Re:What could possibly go wrong by nitehawk214 · 2012-11-30 03:03 · Score: 3, Interesting
  
  Yes, lots of people protested NASA's risky space launch of a nuclear reactor but failed to stop the launch. The cops treated them just like they treated OWS. Sigh.
  From the link:
  
  The Cassini rocket will be powered by 72 pounds of plutonium -- the most ever rocketed into space. Protesters say that if the rocket explodes it could sprinkle deadly poison for hundreds of miles.
  Winds can blow (plutonium) into Disney World, Universal City, into the citrus industry and destroy the economy of central Florida," said Michio Kaku, a protesting physics professor from New York. He claimed that casualties could run as high as a million people if there were an accident.
  What? If you split it up into 1 million 30 milligram doses and had people directly inhale it or inject it into your blood, yeah that would do it. You could injest that much and survive (cancer risk goes up, but it is well under the LD50 of 500mg for ingestion, cyanide is more lethal) But exploding it over the ocean where people are very unlikely to encounter any at all? Maybe that is the kind of science you get form a TV physicist. Make up a scary story to get yourself headlines.
  As far as the OWS quip goes, some of these people did break into a secure facility by jumping the fence. Though they deserve to be arrested it is no reason for police brutality. However the article only says that there were only arrests.
  
  --
  I'm a good cook. I'm a fantastic eater. - Steven Brust
22. Re:What could possibly go wrong by MichaelDelving · 2012-11-30 04:09 · Score: 2
  
  Bzzt.
  Your 52kg figure is for a naked sphere of U235. This article mentions a reflector. This article also makes no mention of a second mass, or that the reactor ever reaches criticality. Sub-critical assemblies can still multiply the flux from a static neutron source, so plenty of power with no potential of runaway reactions. Also, the article is about deep-space missions and mentions probes. So I'm guessing no crew, no halves, and no fizzouts.
23. Re:What could possibly go wrong by Chris+Burke · 2012-11-30 04:29 · Score: 1
  
  No, it isn't strange that radiation exposure at and immediately after a nuclear blast would be deadly, and not long afterward a small, even negligible effect.
  
  --
  
  The enemies of Democracy are
24. Re:What could possibly go wrong by whitroth · 2012-11-30 06:52 · Score: 1
  
  Have you ever actually looked up the construction of an RPG? Even with the rocket blowin up, the odds were that it would come down in one lump.
  And considering I heard about it during the demonstrations by idiots by my late ex, who worked as an engineer at the Cape for 17 years, and was in charge of the propellent systems on Cassini-Huygens, I'd belive her.
  And just to aggravate more people, I also am strongly against nuclear power plants. You're for them... have you contacted your Congresscritters and local government, to let them know that you want nuclear waste storage facilities near you?
  mark
25. Re:What could possibly go wrong by cusco · 2012-11-30 07:50 · Score: 1
  
  'risky' my pale pink ass. No one ever protests when the military launches RTGs, and they've had several of them fail to reach orbit. The things are designed to deal with a few hundred tons of explosive blowing up under them. Some of them have been fished out of the ocean, refurbished, and relaunched on a later mission.
  
  --
  "Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin
26. Re:What could possibly go wrong by mcgrew · 2012-11-30 08:31 · Score: 1
  
  He had no health problems that could be attributed to radiation. Those of his friends and shipmates who were there also were the same. In every case when they suffered serious ill health it was due to smoking or drinking.
  They blame everything on smoking and drinking. You got cancer? Smoking! Oh, you didn't smoke? Second hand smoke! My uncle died of lung cancer in his seventies, and he attributed it to the cigarettes he'd stopped smoking 20 years earlier. No mention of the chemicals he was exposed to in his landscaping business, or any of the toxic stuff he was exposed to as a career miltary man.
  As to drinking, what health problems are caused by drinking, aside from chirrosis, which you pretty much have to drink hard liquor from as soon as when you get out of bed to when you pass out at night to catch (yes, I know several people with that disease).
  One child in 4 or five having birth defects when there was none previously in the family, after being exposed to something that's been proven to change DNA and you're still skeptical it was the radiation?
  How old was your dad when he died, and what did he die of? If he's still alive, you have a damned good point, all the WWII vets I've known are dead, my drinking buddy Ralph having died at age 86 a few years ago when his appendix exploded and teh ornery old bastard refused to go to the doctor. Yet, 86 is a pretty good run; I've had quite a few friends a lot younger than me die from cancers and heart disease.
  As to radiation, yes, we are exposed to low levels of it daily.
  
  --
  Free Martian Whores!
27. Re:What could possibly go wrong by The_Laughing_God · 2012-11-30 08:52 · Score: 2
  
  No, "critical mass" is defined as the amount that can create sufficient runaway escalation of the fission rate by capturing the energetic byproducts of fission to stimulate more fission in a positive feedback loop.
  I'll tell you what: I'll give you 1 gram of the radioactive isotope of your choice, if you can stop its fission. You can't. You can only moderate its rate somewhat. Clearly it's self-sustaining on every level down to the individual atom
28. Re:What could possibly go wrong by Anonymous Coward · 2012-11-30 11:23 · Score: 0
  
  An exponential decay is a wonderful thing; most everything is gone after a couple of weeks.
29. Re:What could possibly go wrong by Sussurros · 2012-11-30 12:01 · Score: 1
  
  My sample is very small, only four people. but none of them ever had any kind of cancer. The three whose deaths I know about were caused by strokes or a heart attacks.
  
  Smoking is a cause of both heart attack and emphysema - I once imitated my father's emphysema cough at work to get an afternoon off and so scared my bosses that I was immediately rushed to sick bay and had to admit to the medic what I'd done to avoid being sent to the hospital for tests.
  
  Drinking is linked in these men's cases with Korsakov's syndrome, getting drunk and being run over and probably the strokes. My Old Man never got over having to clean up the remains of his friend who was killed half an hour after reliving my father as gun-layer in 1944. At one point he drank so much that the soles of his feet were two masses semi-supporating disgustingness. He was left by a woman who had no further use for him, found himself a woman who needed him, got his house and himself in order, lived for another quarter century drinking very little and smoking a lot. He died at the age of 77 of a stroke.
  
  As for being sceptical, well, let's just say that I've seen a lot of genuine coincidences and I've learned to never discount the possibility, It's my personal belief that the two are a straight cause and effect situation but I'm not going to discount the possibilty of a series of coincidences.
  
  --
  I said - don't look Ethel!..., but it was too late..., she'd already looked.
30. Re:What could possibly go wrong by Nostromo21 · 2012-12-02 17:05 · Score: 1
  
  Whoosh!
  Were you under the impression that I was a nuclear physicist or claimed to be...?
  Opening with a Bush video on the topic should have been the first (and final) clue ;-p.
  In any case, I agreed, if indirectly - no matter what radioactive material you use, it shouldn't be that hard to keep it sub-critical in a decent sized ship, manned or unmanned (yes, probably less chance of human error in an unmanned one!). The greater issue would be radiation leakage or exposure for long flights.
  And testing fission drives on unmanned probes would only be a first step - how long do you think before they stick humans in there ffs? Why even do tests without the intention, seriously?
Plutonium upgrade by Anonymous Coward · 2012-11-29 15:20 · Score: 0

Great to see development in this area, although surprising to learn that we are sending so many deep space probes that plutonium supply is an issue
1. Re:Plutonium upgrade by cbhacking · 2012-11-29 15:30 · Score: 4, Informative
  
  It's probably less the number of probes we're sending, and more the general decrease in amount of Plutonium. PU hasn't been manufactured much since the end of the cold war; everybody is busy stepping down their weapon programs instead. Now, some of that former-warhead material is great for RTGs, but the stuff degrades. It has a moderately short half-life (it has to, or it wouldn't be active enough to passively generate the heat needed for an RTG) and a lot of the stuff that was viable for spacecraft 30 years ago is pretty cold now (see the Voyager probes, for example, which are running on extremely low power).
  They can't just fix the problem by sending more, either; not only is it in short supply in general, but it's too heavy to send much on a spacecraft. Instead, they send enough to run the mission at full capacity for a few years, scaling back over time. That requires a supply of pretty fresh / pure Plutonium though, and that means making and separating more of it... except doing runs into a serious political problem. We *could* keep using RTGs (although they aren't perfect by any means, they get the job done) if we could convince people to let us manufacture their fuel source...
  
  --
  There's no place I could be, since I've found Serenity...
2. Re:Plutonium upgrade by Anonymous Coward · 2012-11-29 16:02 · Score: 3, Informative
  
  It is a common misconception that weapons grade plutonium can be repurposed for RTGs. However weapons grade plutonium is Pu-239, and has a long half life, 24000 years making it unsuitable for an RTG. The plutonium used in RTGs is Pu-238, with a half life of just 88 years, and is specially made for RTG purposes.
3. Re:Plutonium upgrade by necro81 · 2012-11-30 00:56 · Score: 3, Informative
  
  a lot of the stuff that was viable for spacecraft 30 years ago is pretty cold now (see the Voyager probes, for example, which are running on extremely low power).
  The halflife of Pu-238 is 88 years. The Voyagers' Pu is only about a half-of-a-halflife old. The falloff in power for a Pu RTG is due largely to material degradation in the thermocouples that generate electricity, not due to a drastic falloff in heat.
The US is actively destroying it's Plutonium by SampleFish · 2012-11-29 15:22 · Score: 2

I found it odd that this little blip state that Plutonium is in short supply. The reason we don't have a lot of it is because the US is actively destroying it's Plutonium reserves. There are countless patents for machines that destroy Plutonium. Here is an article about how the DOE is considering alternatives to destroying Plutonium, like using it for something constructive instead of making bombs. http://www.world-nuclear-news.org/ENF_Alternative_route_for_plutonium_destruction_1507091.html
1. Re:The US is actively destroying it's Plutonium by Anonymous Coward · 2012-11-29 15:33 · Score: 2, Informative
  
  The usual plutonium bomb/reactor fuel is Pu 239, which is not exactly common (consider how hard Iran tries to get its hands on some). Pu 238 is much rarer than Pu 239, because of its short half life (87.7 years compared to 1000's of years). That higher radioactivity is also why it's usable in an RTG (thing that generates power by the heat of radioactive decay). With a fission reactor they could use Pu 239 which is (to nuclear countries like the US) plentiful, relative to small uses like this.
2. Re:The US is actively destroying it's Plutonium by Anonymous Coward · 2012-11-29 15:35 · Score: 2, Informative
  
  It is truly an irrational pursuit that only sees these materials as weapons. It is our most valuable resource. Actually that would be U-235. We could be using it a lot more efficiently in a new generation of molten salt type reactors.
3. Re:The US is actively destroying it's Plutonium by Anonymous Coward · 2012-11-29 16:18 · Score: 0
  
  Because they use Pu-239 and the other types (Pu-240, Pu-238, etc.) are considered waste from nuclear bomb standpoint. Hence they are "using" them by mixing them with depleted fuel and using it as fuel for nuclear reactors.
  So yes, US maybe destroying plutonium, but only the stuff they can't use to make bombs. The superenriched (95+% enrichment) Pu-239 warheads are what US is concentrating their nuclear arsenal in. Dial-a-yield type of nukes you put on cruise missiles.
  Anyway, back to watching football.
4. Re:The US is actively destroying it's Plutonium by rubycodez · 2012-11-29 16:42 · Score: 4, Insightful
  
  even depleted u-238 can be used in the right type of reactor, and thorium too. we have millenia of fission fuel supply, we just need to start using smart designs rather than the primative and dangerous gen i and ii
5. Re:The US is actively destroying it's Plutonium by Anonymous Coward · 2012-11-29 16:56 · Score: 0
  
  You can't deduce that plutonium is in short supply from the fact that plutonium-238 is in short supply anymore than you can deduce that turtles are endangered from the fact that leatherback turtles are endangered. (But I wouldn't expect that level of logical thinking from someone who types "it's Plutonium".)
6. Re:The US is actively destroying it's Plutonium by Anonymous Coward · 2012-11-29 19:42 · Score: 0
  
  For fission energy production, we must start with a fissile resource (we need the neutrons!), and the only natural fissile element in any feasible quantity is U235. Of course, once we start there we can create more fissile material from U238 and Th232 (with breeders or converters, fast or thermal reactors). So let me repeat my earlier assertion: U235 is currently the most valuable energy resource we have.
7. Re:The US is actively destroying it's Plutonium by Anonymous Coward · 2012-11-29 22:58 · Score: 0
  
  For fission energy production, we must start with a fissile resource (we need the neutrons!), and the only natural fissile element in any feasible quantity is U235.
  I don't like processes that are too autonomous and have a mind of their own. That's how you get Chernobyl and Fukushima. Why don't we just use Farnsworth fusor or similar to generate needed neutron flux to stimulate fission of U238 or Thorium, and do away with chain reaction completely? That would make process more controllable and eliminate possibility of runaway.
8. Re:The US is actively destroying it's Plutonium by khallow · 2012-11-30 02:08 · Score: 1
  
  For fission energy production, we must start with a fissile resource (we need the neutrons!)
  You can also start with a fusion source for those neutrons. Farnsworth fusor seems to generate a bunch of neutrons with sufficient energy to induce fusion in U-238 (Wikipedia currently is claiming that the fusor can generate neutrons of almost 2.5 MeV and simultaneously claims that neutrons of 1 MeV are the minimum needed to induce fission of U-238.
9. Re:The US is actively destroying it's Plutonium by Anonymous Coward · 2012-11-30 02:22 · Score: 0
  
  I don't like processes that are too autonomous and have a mind of their own. That's how you get Chernobyl and Fukushima.
  This is nonsense. You get Chernobyl by designing poorly and short circuiting every process you have. You get Fukushima by having multiple once-in-a-lifetime disasters happen at once. It's not because the U238 decay chain has a 'mind of it's own', like it's going out and doing shit.
10. Re:The US is actively destroying it's Plutonium by John+Hasler · 2012-11-30 02:24 · Score: 1
  
  > I found it odd that this little blip state that Plutonium is in short supply.
  Plutonium 239, used in weapons, isn't in short supply. Plutonium 238, used in RTGs, is.
  
  --
  Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
11. Re:The US is actively destroying it's Plutonium by Waffle+Iron · 2012-11-30 02:56 · Score: 0
  
  It is truly an irrational pursuit that only sees these materials as weapons. It is our most valuable resource. Actually that would be U-235. We could be using it a lot more efficiently in a new generation of molten salt type reactors.
  When will all the pro-nuke dorks on this site get it through their heads that the problem with fission power is NOT TECHNICAL. And that therefore, no newfangled fission technology will accomplish anything.
  The problem with fission power is human nature. If this species were competent enough to obtain the majority of its power from nuclear fission, we wouldn't be drawing up war plans right now over Iran's nuclear "power" program.
12. Re:The US is actively destroying it's Plutonium by Anonymous Coward · 2012-11-30 03:29 · Score: 0
  
  Time is actively destroying the US' plutonium supply. The US is just not replenishing it.
13. Re:The US is actively destroying it's Plutonium by Teancum · 2012-11-30 04:59 · Score: 1
  
  The problem with a Fusor is that the energy requirements necessary to get it to produce that neutron flux is quite high. Not only does the Fusor not really produce a net energy gain to sustain fusion on its own, but using those neutrons on Uranium would also be prohibitively expensive in terms of shoveling coal into a boiler to produce the electricity necessary to power the Fusor in order to manufacture the Plutonium. Yes, it could be done, but there are much easier ways to get the job done at far less cost.
  Mainly I'm saying this is an economic rationale where building such a device for making RTGs is sort of lame and expensive. If you were a desperate country like North Korea and didn't otherwise give a damn about power requirements in your quest for making a bomb, I suppose that would be one way to enrich Uranium to manufacture Plutonium. But if you have access to large quantities of Uranium and can write your own regulatory rules, why are you bothering with such silly methods of nuclear alchemy?
  A Fusor is a fun tool to play with in a chemical laboratory if you don't mind just playing with a few atoms of some exotic material, and it has been built commercially for such applications. This isn't a completely cracked up idea, so it does deserve at least thinking about the idea for a bit and understanding what your application might be for generating Plutonium.
14. Re:The US is actively destroying it's Plutonium by rubycodez · 2012-12-04 10:50 · Score: 1
  
  wrong, even depleted uranium can be used ALONE as a sole fission source in the right type of reactor that even a third world country can build (e.g. graphite moderated)
15. Re:The US is actively destroying it's Plutonium by Anonymous Coward · 2012-12-13 20:22 · Score: 0
  
  Pro-nuke dorks? Name-calling, much?
  "Newfangled fission technology" is inherently safer due to passive sophistication: If a core gets too hot in some newer designs, the entire thing collapses without mechanical intervention, thereby inhibiting further reaction. The biggest issues with building new plants are regulation in place because of paranoia. In a logical world, safety should reduce paranoia.
  http://en.wikipedia.org/wiki/Passively_safe
  Iran's leaders say 9/11 was a conspiracy created by the West to justify war on Islam. Nuclear capability is just a convenient justification to remove ridiculous people from positions of power.
  http://en.wikipedia.org/wiki/Mahmoud_Ahmadinejad#United_States
Re:Los Alamos is located in Nevada, a blue state. by Anonymous Coward · 2012-11-29 15:24 · Score: 5, Funny

This is the most beautiful poetry I have ever seen. Oh my God.
Re:Los Alamos is located in Nevada, a blue state. by Anonymous Coward · 2012-11-29 15:30 · Score: 5, Funny

You must be a Vogon.
It's true by Anonymous Coward · 2012-11-29 15:38 · Score: 0

The name of the experiment is a Simpsons reference.
1. Re:It's true by one+eyed+kangaroo · 2012-11-29 15:50 · Score: 2
  
  Yes, I love it that they use a device called a "DUFF which "is a sort of lab bench nuclear reactor". ;-)
2. Re:It's true by Black+Parrot · 2012-11-29 19:36 · Score: 1
  
  Yes, I love it that they use a device called a "DUFF which "is a sort of lab bench nuclear reactor". ;-)
  
  Hopefully none of the researchers will get caught sitting on their DUFF.
  
  --
  Sheesh, evil *and* a jerk. -- Jade
polemic----word of the day by Anonymous Coward · 2012-11-29 15:39 · Score: 0

how can i work this one in here?
1. Re:polemic----word of the day by Anonymous Coward · 2012-11-29 17:23 · Score: 0
  
  how can i work this one in here?
  Well, not asking stupid questions would be a good start.
Pu-238 is not Pu-239. by jeffb+(2.718) · 2012-11-29 15:56 · Score: 5, Informative

It seems like you're confusing Pu-239, which is used in weapons and has a half-life of 24000 years, with Pu-238, which is not used in weapons and has a half-life of around 90 years.
1. Re:Pu-238 is not Pu-239. by Bomazi · 2012-11-29 18:43 · Score: 3, Informative
  
  Pu-238 is not used in nuclear explosives proper but some nuclear weapons use a Pu-238 fueled RTG as a power source (see RCED-97-52, section "ELECTRICAL POWER SOURCES").
  Historically most Pu-238 was produced for security applications. The space program was a minor user. The end of the cold war caused a dramatic reduction in the number of weapons. Thus the existing stockpile plus the Pu-238 recovered from dismantled weapons constituted a more than adequate reserve that rendered continued production unnecessary.
  Today they are comparatively few weapons and most have migrated to different power sources. Hence the space program can no longer count on the nuclear weapons program to "subsidize" production. If it wants more Pu-238 it will have to cover a large portion of the cost of restarting production. We can thus expect RTGs to be used less often than in the past.
Less moving parts by Anonymous Coward · 2012-11-29 16:25 · Score: 0

I was going to ask why they would use moving parts instead of something like cool chips (quantum electron tunneling). But then I realized that there probably isn't anything that is tested and ready yet. Then I realized that posting on Slashdot about things I know nothing about, will probably inflame the pedants and incite comments regarding my lack of knowledge and poor grammar/spelling. But then I posted anyway.
1. Re:Less moving parts by Black+Parrot · 2012-11-29 19:37 · Score: 2
  
  I was going to ask why they would use moving parts instead of something like cool chips (quantum electron tunneling). But then I realized that there probably isn't anything that is tested and ready yet. Then I realized that posting on Slashdot about things I know nothing about, will probably inflame the pedants and incite comments regarding my lack of knowledge and poor grammar/spelling. But then I posted anyway.
  We are indeed inflamed, and our comments are duly incited.
  
  --
  Sheesh, evil *and* a jerk. -- Jade
Fission Reactor by Anonymous Coward · 2012-11-29 16:58 · Score: 0

Fission reactor seems like a poor choice of words. I imagine most people thing of a process that actively accelerates a reaction as a reactor, while this is a heat engine running off of nuclear decay heat. However I don't know what a proper description would be.
1. Re:Fission Reactor by esldude · 2012-11-29 17:23 · Score: 3, Informative
  
  You might want to read a bit about fission reactors. A controlled reaction producing heat to be used. That is what it is. It isn't a pile of hot isotopes. Those have been used in the past. As often the case, reading the article might have helped. Or maybe reading about fission reactors on Wikipedia. Good luck.
2. Re:Fission Reactor by Anonymous Coward · 2012-11-29 17:26 · Score: 1
  
  Fission reactor seems like a poor choice of words. I imagine most people thing of a process that actively accelerates a reaction as a reactor, while this is a heat engine running off of nuclear decay heat. However I don't know what a proper description would be.
  Yeah and what causes that decay heat? That's right, fission.
  
  Thank you for playing.
3. Re:Fission Reactor by Genda · 2012-11-29 18:42 · Score: 1
  
  A thermonuclear hot pocket???
  Perhaps a hot neutron enema???
4. Re:Fission Reactor by Neil+Boekend · 2012-11-29 19:09 · Score: 3, Interesting
  
  It is a fission reactor.
  The reactor speed is controllable with a boron carbide control rod. If it was just nuclear decay then it would not be controllable. The "old" RTG's were just powergenerators running off decay energy.
  
  By the way: how did you think a normal fission reactor works? It's just enhanced and controlled nuclear decay that heats up a bunch of water to form steam. This steam dives a turbine that drives a generator: He presto, power! (for a more detailed explanation: just ask. I don't know the details of the reactions but others here do.)
  The main difference here is that they used Stirling engines and scaled it down big time. Sterling engines are probably used because they are incredibly reliable, despite being expensive and not very efficient. There is no way to fix a broken power supply in space, especially if you need to replace parts.
  
  --
  Well, I might have a way, but it only works on a semi spherical planet in a vacuum.
5. Re:Fission Reactor by jgtg32a · 2012-11-30 01:32 · Score: 1
  
  Sterling engines ... not very efficient.
  ???
"DUFF" you say? by Anonymous Coward · 2012-11-29 17:05 · Score: 1

Am I the only one thinking of beef/simpsons when I read this?
One of the things about RTGs is that compared to SRGs, it has no moving parts.
It has been developed for some time and has been proven to be very reliable.
They can always look at other non-Plutonium isotopes for RTGs such as Americium-241 which has a significantly longer life-span (Am-241's half-life is 432 years while Pu-238 is 87.7)
It also looks like there are some organizations working on a more advanced STG
Too bad the article doesn't go into detail as to which isotope of Uranium it uses.
Some can be really power like U-235 which the BES-5 RTG used though it had one downside of generating lots of Beta radiation.
btw, to /. dev team....it would be nice if the comment submission/preview system was more back-button friendly. Losing what I wrote and having to rewrite it from scratch is a pain.
seems like a downgrade by Anonymous Coward · 2012-11-29 17:24 · Score: 1

We are moving from a heat driven passive reactor to a heat driven mechanical generator... seems like step back and a new point of failure for modern space vehicles...
1. Re:seems like a downgrade by Anonymous Coward · 2012-11-29 18:38 · Score: 0
  
  We are moving from a heat driven passive reactor to a heat driven mechanical generator... seems like step back and a new point of failure for modern space vehicles...
  Except for the fact that with a reactor you can regulate the power output, extract more energy out of a given mass of radioactive material, plan for longer mission envelopes/reduce launch mass, I suppose you're right.
2. Re:seems like a downgrade by Genda · 2012-11-29 18:47 · Score: 2
  
  Nah, the younger engineers are just infatuated with steam-punk... Wait till you see the generation of satellites with the brass fittings... woohoo!,/p>
3. Re:seems like a downgrade by funkboy · 2012-11-29 22:40 · Score: 1
  
  We are moving from a heat driven passive reactor to a heat driven mechanical generator... seems like step back and a new point of failure for modern space vehicles...
  Stirling Engines are actually quite reliable. They're often used on things like waste heat recovery systems to power remote oil & gas installations, where they have to run for extended periods in nasty environments.
  The main limitation to more popular use of Stirling-cycle engines vs. the ICE is that they need an external source of motion to get them going (well, ICEs do too), and they take a while to "warm up" before they reach operational efficiency. Ford messed with them for a while in the 70's when the gas crisis hit and managed to get the start/warmup cycle to down to about 30 seconds.
  So not an excellent candidate for applications with a lot of start/stop activity, but very good for generators that just need to sit there & run forever.
4. Re:seems like a downgrade by careysub · 2012-11-30 05:45 · Score: 1
  
  Would be perfect for an advanced hybrid vehicle using all-electric drive. The combustion engine is there just to keep the battery pack charged, a 30 second warm-up (for a 3 minute warm-up for that matter) would be fine.
  
  --
  Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
Re:Los Alamos is located in Nevada, a blue state. by Anonymous Coward · 2012-11-29 18:22 · Score: 0

Ignoring the stupidity of the text, while the assembly was sone in a facility in Nevada, Las Alamos is located in New Mexico.
When do we get them? by evilviper · 2012-11-29 18:57 · Score: 1, Interesting

When do we get them? Electric cars are all the rage... Imagine you had a non-stop range extender! Imagine your car just charges itself when parked anywhere. Better yet, imagine an RV powered by one of these... park out in the middle of nowhere, and still have a decent amount of power. Or in some cases where communities are isolated, how about end-of-the-block SRGs? The best thing about an EV/RV SRG is that the half-life is about 80 years, so just one will last you a couple lifetimes.
A number of years ago, I balparked the cost of RTGs, based on some unverified found info, and decided they were impractically expensive... But with SRGs dramatically improving the efficiency, the cost of the plutonium-238 to power one that'll be a usefully large (for range xextending EV's) would only run a bit over $100,000... a practical sum of money for a very large number of people. So when can we expect to see them on the market?

--
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
1. Re:When do we get them? by dbIII · 2012-11-29 19:27 · Score: 1
  
  Better yet, imagine an RV powered by one of these
  Hmm, 24 Watts.
  Yep, I can imagine it, an RV up on blocks in a yard and not going anwhere :)
  
  There's a bit of an awkward gap between little Stirling engines and a honking great big reactor that can move a submarine. I'm not sure if there's anything in that gap - anyone out there with some ideas?
2. Re:When do we get them? by funkboy · 2012-11-29 22:43 · Score: 1
  
  Hmm, 24 Watts.
  FTFA:
  
  “The nuclear characteristics and thermal power level of the experiment are remarkably similar to our space reactor flight concept,” said Los Alamos engineer David Poston. “The biggest difference between DUFF and a possible flight system is that the Stirling input temperature would need to be hotter to attain the required efficiency and power output needed for space missions.”
  Though successful, the Stirling engine system used in the experiment isn't considered enough for practical purposes. For missions beyond Jupiter, much more power is needed. “The heat pipe and Stirling engine used in this test are meant to represent one module that could be used in a space system,” said Marc Gibson of NASA Glenn. “A flight system might use several modules to produce approximately one kilowatt of electricity.”
  With the right hardware I could build a nice little server farm that runs on a kilowatt... Or even better give me a flywheel that I can charge with the excess mechanical energy generated during off-peak periods and tap during peaks, and double the peak load of the system.
3. Re:When do we get them? by Hentes · 2012-11-29 23:15 · Score: 1
  
  Giving radioactive materials to the general populace can be dangerous. There are bad people out there.
4. Re:When do we get them? by Anonymous Coward · 2012-11-29 23:59 · Score: 0
  
  Worse still, there are stupid people out there.
5. Re:When do we get them? by CanadianRealist · 2012-11-30 01:51 · Score: 1
  
  True, but there are way more stupid people out there than bad people so...
  Hmm, I guess I need to think a bit more about my counter argument. Let me get back to you.
6. Re:When do we get them? by kilodelta · 2012-11-30 03:17 · Score: 1
  
  I thought about this too. You could have community based reactors but then it also occurred to me that you'd also have a ready source of catastrophe every few thousand feet. Knowing the electrical provider in my area, I know it's a disaster just waiting to happen.
  
  Between utility poles and manhole covers with voltages on them to theft of manhole covers it's getting interesting.
  
  In case you're wondering, it's National Grid.
7. Re:When do we get them? by Plazmid · 2012-11-30 03:31 · Score: 1
  
  When the governments of the world decide it's ok for civilians to own weapon's grade uranium.
  TFA mentions that the reactor uses a 50 lb, which is about half the critical mass of uranium 235. In order for the core to maintain a fission reaction, even with the neutron shield in place, it's probably going to use weapons grade uranium.
  There's been a pretty big effort to cut down on civilian usage of weapon's grade uranium(IE research reactors) and other fun fissile substances for fear of people making bombs from them.
8. Re:When do we get them? by decipher_saint · 2012-11-30 03:39 · Score: 2
  
  I'm sure that in 1985, plutonium is available in every corner drugstore, but in 2011, it's a little hard to come by.
  
  --
  crazy dynamite monkey
9. Re:When do we get them? by evilviper · 2012-11-30 06:27 · Score: 0
  
  Giving radioactive materials to the general populace can be dangerous.
  
  Outlaw smoke detectors!
  I'm sure most radioactive materials are less dangerous than, say, fertilizer or gasoline.
  
  --
  Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
10. Re:When do we get them? by MachineShedFred · 2012-11-30 08:48 · Score: 1
  
  Yeah, so that way when you get a 100-car pileup on a Texas freeway, instead of just having the chemical danger of automotive fluids and lubricants, you also get a nice Nuclear Emergency Response Team showing up and scrubbing everyone down!
  
  --
  Slashdot still doesnâ(TM)t support Unicode after it was added to the HTML standard in 1997.
11. Re:When do we get them? by dbIII · 2012-11-30 10:31 · Score: 1
  
  That's getting a bit of a way from an RV and answering a completely different question to the one asked.
12. Re:When do we get them? by evilviper · 2012-11-30 11:10 · Score: 1
  
  NASA's RTGs are damn near indestructible! They fall from orbit without breaking open.
  
  --
  Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
13. Re:When do we get them? by MachineShedFred · 2012-12-03 02:17 · Score: 1
  
  Yeah, but we're not talking about RTGs. RTGs are a lump of Pu-238 with a thermocouple and really couldn't be simpler. TFA is talking about a miniaturized reactor, with a criticality inside, and a mechanical control system that can bend / break / wear out.
  
  --
  Slashdot still doesnâ(TM)t support Unicode after it was added to the HTML standard in 1997.
Dirty bomb is bullshit - shown by Kosmos by dbIII · 2012-11-29 19:21 · Score: 1

Years ago when a Kosmos satellite broke up above Canada the cleanup showed how stupid a myth the dirty bomb idea is. You could make a few real bombs with the material required for an effective dirty bomb.
Re:Los Alamos is located in Nevada, a blue state. by Tablizer · 2012-11-29 19:23 · Score: 5, Funny

It's a HaiKKKu

--
Table-ized A.I.
It's small by Animats · 2012-11-29 20:26 · Score: 3, Informative

Nuclear reactors have been used in space since the 1960s, by both the US and USSR. They've generally powered thermocouple-type electrical generators, which are inefficient but very reliable. The one US reactor launched massed 290Kg and produced 500 watts. Soviet reactors were bigger and produced more power.
The innovation here is a small unit around 65Kg that produces only 24 watts. Electronics has become so low-power that a 24 watt power plant is useful.
Note that all these reactors are unshielded.
1. Re:It's small by Michael+Woodhams · 2012-11-29 22:27 · Score: 1
  
  Are you conflating RTGs and reactors? I associate thermocouples with RTGs, not reactors, and a cursory wikipedia search didn't find any reactors using thermocouples.
  RTGs rely on the natural decay of the radioactive fuel, whereas reactors use a chain reaction to accelerate the decay of the fuel. Voyager etc. use RTGs with thermocouples. The device here is an actual reactor, with a control rod and neutron reflector. I'm aware that the U.S.S.R. built reactors for space. Wikipedia lists a few NASA reactor projects, but I'm not sure any of them actually flew. I'm not aware of a reactor being used in an interplanetary probe.
  
  --
  Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
2. Re:It's small by Anonymous Coward · 2012-11-29 23:49 · Score: 0
  
  Reactors are inerently far less reliable than RTGs. RTGs have no moving parts, are always self-limited and require absolute no control loops of any sort, just bog standard electric power conditioning. Reactors have moving parts, are not self-limited (and thus have horrible failure modes that destroy the spacecraft. For RTGs, you use multiple units -- voyager had three I believe, and just kick off-bus one that has a critical failure), and if it is using a Stirling engine, it means it has
  always-moving parts which is extremely foolhardy for very long term missions (i.e. anything spaceproble-class).
  It really would be much better to make some Pu-238. The big deal is that the USA does not know anymore how to exactly make it, so restarting production will require some quite expensive engineering to rediscover a few key parts of the production process, etc. It would be better to empower a third-world country which
  signed the non-ploriferation of nuclear weapons world treaty and has no real nuclear warhead dreams (e.g. Brazil) to make the Pu-238.
3. Re:It's small by Animats · 2012-11-30 04:39 · Score: 1
  
  Are you conflating RTGs and reactors? I associate thermocouples with RTGs, not reactors, and a cursory wikipedia search didn't find any reactors using thermocouples.
  No, I'm not The US launched one reactor, and it used a thermocouple-type generator. The USSR launched many radar satellites with reactors in the 1KW to 5KW electrical output range. One crashed into Canada.
We should NOT be using nuclear in space by Anonymous Coward · 2012-11-29 21:58 · Score: 2, Funny

Why contaminate the rest of the Universe? We have ruined our own planet and now we're going to ruin someone else's.
They should only allow green energy in space - solar, or hydro, or wind turbines. Wind turbines would work fine on Mars...
1. Re:We should NOT be using nuclear in space by stiggle · 2012-11-30 00:47 · Score: 2
  
  Quick - shut down that large unshielded nuclear furnace in the sky!
  Oh yeah, thats the sun.
  Properly used - nuclear is a very green energy and no greenhouse gasses or climate change to worry about.
  You need something to provide a constant baseload for the times when the sun don't shine and the wind don't blow.
Is that legal? by Taco+Cowboy · 2012-11-29 22:22 · Score: 1

...while the assembly was sone in a facility in Nevada...Las Alamos is located in New Mexico.
Question: Is it legal to transport radioactive material across state-line?

--
Muchas Gracias, Señor Edward Snowden !
1. Re:Is that legal? by NibbleG · 2012-11-30 00:09 · Score: 1
  
  With proper permits yes, You and I will never get those permits approved, but NASA can.
2. Re:Is that legal? by shaitand · 2012-11-30 06:04 · Score: 1
  
  You haven't broken the law until you are convicted. Last I checked NASA hasn't been convicted of anything.
3. Re:Is that legal? by cbhacking · 2012-11-30 07:09 · Score: 1
  
  Nope. Every single nuclear reactor now operating had to be fueled from the ground it was built on. It was even harder for missiles and bombs; they had to be built in border states so that the material could leave the country directly without being flown over another state. Also, all of those previous space probes and rovers with RTGs had to have the plutonium produced right in Florida where they could be launched.
  </sarcasm>
  Yes, of course it's legal. It requires permits, just like it required permits to even possess enriched uranium, but the stuff has legit civilian uses and transporting it can be legitimately arranged.
  
  --
  There's no place I could be, since I've found Serenity...
4. Re:Is that legal? by MachineShedFred · 2012-11-30 08:46 · Score: 1
  
  If it isn't, then a significant portion of the Air Force and Navy would need to be locked up.
  
  --
  Slashdot still doesnâ(TM)t support Unicode after it was added to the HTML standard in 1997.
5. Re:Is that legal? by distilate · 2012-11-30 10:33 · Score: 1
  
  I prefer to transport mine on home built UAVs. non traceable convenient and much quicker than all the paperwork
Reliability? by argStyopa · 2012-11-29 23:46 · Score: 2

IANARS, but it seems to me that while this is a great idea, there's a weak point in the mechanical linkages and the stirling engine.
RTGs use thermocouples which, while never very efficient, have the advantage of being solid state - a huge reliability benefit.
If you have this sort of system powering deep-space probes (or hell, near-space systems) I'd think that aside from all the normal wear-and-tear issues of any linkage (lubrication, debris, even erosion over time) would be exacerbated by the thermal extremes in space. Further, the vibration created through the rest of the craft couldn't be helpful for the lifespan of the other components. Finally, for the sorts of precision needed for space operations (pointing a space telescope comes to mind) the constant oscillation of mass within the craft probably would make other things significantly more difficult.
Again, not a rocket scientist, but from my point of view as 'cool' as this is, and as useful as it may be, it doesn't seem like something very applicable to space operations.
Tinfoil hat bit:
Now...if one needed a long-term power source for something much less precise like earthly drone operations... (I don't know the mass/power here at all)...

--
-Styopa
1. Re:Reliability? by hpa · 2012-11-30 06:36 · Score: 1
  
  The use of Stirling engines has already been planned for future RTG missions, this is just a change of heat source.
I want one! by Sun.Jedi · 2012-11-30 01:22 · Score: 1

Put one of these in my backyard and let me plug in. There, now you have it, I'm willing to go green (nuclear green) for my electricity.
'cause we are dead.Re:What could possibly go wrong by Anonymous Coward · 2012-11-30 03:11 · Score: 0

Yes, lots of people protested NASA's risky space launch of a nuclear reactor but failed to stop the launch. The cops treated them just like they treated OWS. Sigh.
yes, that is sad -- we wouldn't all be dead right now if NASA had been stopped.
Re:Not Impressed nor Worried by kilodelta · 2012-11-30 03:12 · Score: 1

Wow - someone can expect a visit from the USSS pretty soon!
Mod parent up! by Anonymous Coward · 2012-11-30 04:39 · Score: 0

Came for this; was not disappointed.
Launching a reactor is safer than launching an RTG by hpa · 2012-11-30 06:34 · Score: 0

One thing that is not really covered is that launching a reactor (unlike *operating* a reactor in *low-earth orbit* like the Soviets did) is that it is substantially safer than launching an RTG. An RTG is at its maximum activity at the point of launch, and in the case of a low altitude launch failure could spread measurable radiation over an area. In contrast, the reactor isn't (shouldn't be) activated until already on an earth escape trajectory. "Virgin" (never irradiated) U-235 is not very radioactive: the specific activity is some 8,000,000 times less than Pu-238. If the reactor ends up having a failure and a meltdown it is already on its way away from Earth never to return, and there really is no better dump for nuclear waste than deep space.
moving parts. in space. by Anonymous Coward · 2012-11-30 07:01 · Score: 0

well, maybe it will be ok with regular oil changes.
except it wont get any.
because it will be... in space.
Pu-238 is in short supply BECAUSE... by gordm · 2012-11-30 07:50 · Score: 1

...the Pu-238 contained within USA's existing U-233 stockpile is being destroyed along with it. http://www.youtube.com/watch?v=-p49Sq7mbpE

Also, the U-233 could serve as a "nuclear catalyst" in Molten Salt Reactors fed Thorium as fuel. Such reactors could produce Pu-238 in an easily partition-able form since they would be in a liquid state, and there would be no unwanted isotopes to contaminate the plutonium. (Isotopes being harder to separate than other elements.)

If you live in the USA please consider dropping your email in here... http://thoriumpetition.com/

...and you'll be notified when the next petition is launched. Last petition hit ~2500 sigs so there's a ways to go, but by building up the email list should ultimately get there.
I wonder about this by roc97007 · 2012-11-30 08:37 · Score: 1

The difference between this approach and, for instance, the radioisotope thermoelectric generator that is *still* powering two Voyager spacecraft after 35 years, is the inclusion of parts that must move repeatedly to generate electricity. Is this really a good idea?

--
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
1. Re:I wonder about this by DMUTPeregrine · 2012-11-30 13:39 · Score: 1
  
  Yes. The thermocouples powering voyager (the T part of RTG) are degrading, and currently only producing about half their original output. A stirling engine can be made very reliable, more so than a thermocouble.
  
  --
  Not a sentence!
2. Re:I wonder about this by roc97007 · 2012-12-01 05:44 · Score: 1
  
  Right, but there's different kinds of reliable. For instance, there is mean time between failure, and expected lifespan. A mechanism can be less likely to fail at any given moment, but still have a shorter useful lifespan. Motion implies friction, and requires something to reduce same, whether it be a coating or an actual lubricant (which is unlikely in this case considering the environment). Bearings do wear out over time.
  
  --
  Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.