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New Small Fission Reactor For Deep-space Missions Demonstrated
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."
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
This is the most beautiful poetry I have ever seen. Oh my God.
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!
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...
You must be a Vogon.
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...
Yes, I love it that they use a device called a "DUFF which "is a sort of lab bench nuclear reactor". ;-)
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.
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.
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.
"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
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!
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.
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.
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...
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.
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.
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.
A thermonuclear hot pocket???
Perhaps a hot neutron enema???
No, that's the bean burritos.
I said - don't look Ethel!..., but it was too late..., she'd already looked.
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
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.
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.
It's a HaiKKKu
Table-ized A.I.
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
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
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.
Wouldn't Hydarzine mustle just burn in an explosion?
bickerdyke
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.
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...
...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 !
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
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.
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.
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
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.
The radiation from the blast itself and just after it can be very intense, much more intense than from the fallout.
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.
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.
How do you get a sustained fission reaction without critical mass? Critical mass is defined as the mass required to sustain fission.
Sterling engines ... not very efficient.
???
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
Wow - someone can expect a visit from the USSS pretty soon!
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.
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
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
...the Pu-238 contained within USA's existing U-233 stockpile is being destroyed along with it. http://www.youtube.com/watch?v=-p49Sq7mbpE
...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.
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/
'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
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!
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.
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
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.
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?