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posted by janrinok on Thursday May 03 2018, @12:26PM   Printer-friendly
from the can-it-recharge-my-'phone? dept.

NASA's Kilopower nuclear reactor with Stirling converters (not an RTG) has passed key tests:

The Kilopower team conducted the experiment in four phases. The first two phases, conducted without power, confirmed that each component of the system behaved as expected. During the third phase, the team increased power to heat the core incrementally before moving on to the final phase. The experiment culminated with a 28-hour, full-power test that simulated a mission, including reactor startup, ramp to full power, steady operation and shutdown.

Throughout the experiment, the team simulated power reduction, failed engines and failed heat pipes, showing that the system could continue to operate and successfully handle multiple failures.

"We put the system through its paces," said Gibson. "We understand the reactor very well, and this test proved that the system works the way we designed it to work. No matter what environment we expose it to, the reactor performs very well."

The Kilopower project is developing mission concepts and performing additional risk reduction activities to prepare for a possible future flight demonstration. The project will remain a part of the STMD's Game Changing Development program with the goal of transitioning to the Technology Demonstration Mission program in Fiscal Year 2020.

The full system will generate 10 kW of power, but the prototype tested from November to March was designed to produce just 1 kW. The solid uranium-235 core is safe to handle.

The Kilopower Reactor Using Stirling Technology (KRUSTY) prototype exceeded almost all performance metrics.

Multiple units could power missions on the Moon, Mars, or other destinations:

"Kilopower's compact size and robustness allows us to deliver multiple units on a single lander to the surface that provides tens of kilowatts of power," NASA Associate Administrator Steve Jurczyk said in January.

Also at Beyond Nerva. 3m8s video.

Previously: NASA's Kilopower Project Testing a Nuclear Stirling Engine
Initial Tests of NASA's Kilopower Nuclear System Successful


Original Submission

Related Stories

NASA's Kilopower Project Testing a Nuclear Stirling Engine 23 comments

A NASA project will test a small nuclear fission power system that could provide kilowatts or megawatts of power for space missions:

In preparing for possible missions to the Red Planet in the near future, NASA's Space Technology Mission Directorate (STMD) has been given the go-ahead to test a small nuclear reactor that could one day run equipment on the Martian surface.

The Kilopower project[PDF] is working to advance a design for a compact, low-cost, and scalable nuclear fission power system for missions that require lots of power, such as a human mission to Mars. The technology uses a fission reactor with a uranium-235 reactor core to generate heat, which is then transferred via passive sodium heat pipes to Stirling engines. Those engines use that heat to create pressure, which moves a piston – much as old coal-powered ships used steam pressure to run their pistons. When coupled to an alternator, the Stirling engine produces electricity.

"What we are striving to do is give space missions an option beyond RTGs [radioisotope thermoelectric generators], which generally provide a couple hundred watts or so," Lee Mason, STMD's principal technologist for Power and Energy Storage at NASA Headquarters in Washington, D.C., said in a NASA news release. "The big difference between all the great things we've done on Mars, and what we would need to do for a human mission to that planet, is power."

Mason said the new technology could provide kilowatts of power and even be upgraded to provide hundreds of kilowatts or even megawatts of power. "We call it the Kilopower project because it gives us a near-term option to provide kilowatts for missions that previously were constrained to use less," Mason said. "But first things first, and our test program is the way to get started."

Stirling engine.

Also at World Nuclear News.


Original Submission

Initial Tests of NASA's Kilopower Nuclear System Successful 53 comments

Initial tests of NASA's Kilopower nuclear power system have been successful, and full-power testing will be done in March. Each Kilopower unit is expected to provide between 1 kW to 10 kW of electric power:

Months-long testing began in November at the energy department's Nevada National Security Site, with an eye toward providing energy for future astronaut and robotic missions in space and on the surface of Mars, the moon or other solar system destinations.

A key hurdle for any long-term colony on the surface of a planet or moon, as opposed to NASA's six short lunar surface visits from 1969 to 1972, is possessing a power source strong enough to sustain a base but small and light enough to allow for transport through space. "Mars is a very difficult environment for power systems, with less sunlight than Earth or the moon, very cold nighttime temperatures, very interesting dust storms that can last weeks and months that engulf the entire planet," said Steve Jurczyk, associate administrator of NASA's Space Technology Mission Directorate. "So Kilopower's compact size and robustness allows us to deliver multiple units on a single lander to the surface that provides tens of kilowatts of power," Jurczyk added.

[...] Lee Mason, NASA's principal technologist for power and energy storage, said Mars has been the project's main focus, noting that a human mission likely would require 40 to 50 kilowatts of power. The technology could power habitats and life-support systems, enable astronauts to mine resources, recharge rovers and run processing equipment to transform resources such as ice on the planet into oxygen, water and fuel. It could also potentially augment electrically powered spacecraft propulsion systems on missions to the outer planets.

NASA's next Mars mission is InSight, a stationary lander scheduled to launch in May. It will use two MegaFlex solar arrays from Orbital ATK. NASA's Mars 2020 rover is scheduled to launch in July 2020. It will use 4.8 kg of plutonium dioxide to provide no more than 110 Watts of power.

The Juno mission is the first mission to Jupiter to use solar panels. Juno uses 72 square meters of solar panels to generate a maximum of just 486 Watts at Jupiter. Mars receives about 12 times more solar radiation per m2 than Jupiter. The New Horizons mission to Pluto and Cassini–Huygens mission to Saturn both used radioisotope thermoelectric generators (RTGs). Cassini used three RTGs originally rated for 300 W each. A spare Cassini RTG was used for New Horizons, which provided 245.7 W at launch (~200 W by the Pluto encounter).

The Fission System Gateway to Abundant Power for Exploration

Also at NASA and Popular Science.

Previously: NASA's Kilopower Project Testing a Nuclear Stirling Engine


Original Submission

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  • (Score: 4, Funny) by c0lo on Thursday May 03 2018, @01:09PM (4 children)

    by c0lo (156) Subscriber Badge on Thursday May 03 2018, @01:09PM (#675025) Journal

    N/T

    (grin)

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    • (Score: 1, Touché) by Anonymous Coward on Thursday May 03 2018, @05:09PM (3 children)

      by Anonymous Coward on Thursday May 03 2018, @05:09PM (#675151)

      It's a nuclear reactor, it's supposed to go critical. Maybe you meant prompt critical.

      • (Score: 2) by HiThere on Thursday May 03 2018, @05:29PM (2 children)

        by HiThere (866) Subscriber Badge on Thursday May 03 2018, @05:29PM (#675160) Journal

        Not necessarily. There are designs and designs. Many nuclear-thermal designs just use the heat generated by decay. (Think the Pluto probe.)

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        • (Score: 3, Informative) by takyon on Thursday May 03 2018, @05:54PM (1 child)

          by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Thursday May 03 2018, @05:54PM (#675185) Journal

          Many nuclear-thermal designs just use the heat generated by decay. (Think the Pluto probe.)

          That is a radioisotope thermoelectric generator [wikipedia.org] (RTG), and as is specifically noted in the summary, Kilopower is NOT an RTG. A nuclear reactor [wikipedia.org] initiates a nuclear chain reaction, while an RTG does not. An RTG is not a nuclear reactor.

          A thermionic converter—an energy conversion device which relies on the principle of thermionic emission—can achieve efficiencies between 10–20%, but requires higher temperatures than those at which standard RTGs run. Some prototype 210Po RTGs have used thermionics, and potentially other extremely radioactive isotopes could also provide power by this means, but short half-lives make these unfeasible. Several space-bound nuclear reactors have used thermionics, but nuclear reactors are usually too heavy to use on most space probes.

          Kilopower is a nuclear fission reactor that converts heat to electricity using Stirling engines.

          https://en.wikipedia.org/wiki/Kilopower [wikipedia.org]

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          • (Score: 2) by c0lo on Friday May 04 2018, @12:21AM

            by c0lo (156) Subscriber Badge on Friday May 04 2018, @12:21AM (#675401) Journal

            It still doesn't automatically mean the reactor works in the critical area - a very risky regime, small fluctuations and you can go supercritical/in meltdown easy.
              You can still have a hot reactor using enough mass of "short" life elements using the natural rate of decay (238Pu - 87years half-life) without even using chain reaction.
            Yes, using long life isotopes is likely to require a chain reaction (thus the use of 'sub-/super-/critical regimes', they don't make sense outside the 'chain reaction' condition), but it's not necessary; for instance, if you use a controllable source of thermal neutrons, you can control the rate of reaction without requiring a chain reaction.

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  • (Score: 2) by JoeMerchant on Thursday May 03 2018, @01:14PM (25 children)

    by JoeMerchant (3937) on Thursday May 03 2018, @01:14PM (#675029)

    with the heat being converted to electricity by Stirling engines.

    I know it's one of the best things we have at the moment, but the idea of bearings and seals and similar moving parts being in a primary path between your power source and all of your life support, navigation and communication capabilities, in space... doesn't sound like anything I'd want to use on a long-term mission.

    Also:

    The solid uranium-235 core is safe to handle.

    Really? For what definitions of "safe" and "handle"?

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    • (Score: 2, Interesting) by suburbanitemediocrity on Thursday May 03 2018, @01:21PM (13 children)

      by suburbanitemediocrity (6844) on Thursday May 03 2018, @01:21PM (#675031)

      "doesn't sound like anything I'd want to use on a long-term mission."

      It's all about mtbf and reliability. With proper engineering you can make anything as safe as you want or need. There is nothing intrinsically wrong with mechanical systems.

      • (Score: 5, Informative) by VLM on Thursday May 03 2018, @01:59PM (12 children)

        by VLM (445) Subscriber Badge on Thursday May 03 2018, @01:59PM (#675050)

        Well, I'll try to explain it without any bad SN automobile analogies.

        With a RTG, heat flows across a bulk solid material just like a boring heatsink. The heat-resistance crosses sort of a back-EMF like, um, force, such that its a slightly worse conductor in exchange for a like amount of electrical power generated. It turns out to be pretty easy to size the parts such that short circuiting the RTG won't melt the reactor (as semiconductors are usually not-terrible heat conductors) and open circuiting the RTG obviously means no "force" holding back the heat so if a fuse blows the reactor runs colder than usual, which is usually really good news. Like dumping the load off a series wound motor, nothing too scary happens (usually). Maybe this is a really bad non-technical analogy if I'm talking about series-wound electric motors and stuff.

        With a Stirling, heat flows thru a gas and no engineer has ever made anything that can contain a gas forever, at least relative to nuclear waste length lifetimes, so someday the core will not be cooled at all by the Stirling. Also its like a shunt-wound motor in that the reactor will pump out constant watts of heat (more or less) while shutting off the generator means no gas movement means no cooling, so life gets exciting even if the gas doesn't leak out, if a fuse blows.

        There are engineering solutions to prevent stirling engine meltdown. On the earth we use two, four, six, maybe more coolant loops so none ever fail simultaneously and then put in triple redundant backup emergency coolant systems. And we have smart humans on the ground. Of course you kill lots of the population and destroy all the infrastructure in an earthquake and tsunami like happened in Japan, you're still screwed. Or if the sorcerers apprentice starts pulling levers in a fun experiment like Chernobyl, it goes poorly. Or if something really freaking weird happens and the ops misinterpret the wrong gauges thru a long chain of bad luck, you get three mile island which none the less was pretty safe outcome compared to Chernobyl or Japan's events, so in some ways TMI wasn't a total failure. In space you could hook the reactor up to enough solid metal boring heatsinks such that if the electric stuff totally failed it would still have maybe 25% cooling maybe enough to prevent a meltdown.

        Oh and this is before other fun... The worst thing solids do when you abuse them is crack or melt so RTGs can have the crap beaten out of them, even re-enter the atmosphere, and it'll be "OK" for some value of "OK". However gas/liquid stuff explodes nicely even for strictly speaking non-nuclear explosion reasons. See Japan, Chernobyl, etc. You could build hardware so incredibly strong that the buildings in Japan wouldn't pop or the pipes at Chernobyl wouldn't pop and that would ... more or less work until the fuel melted. But a solid block of a RTG is much more inherently safe.

        Might look like I'm anti-reactor pro-RTG but there are various engineering tradeoffs where one is better than the other despite comments above. A RTG might be a thousand times less likely to create a nuclear superfund site, but it might take ten thousand times the mass of radioactive junk. So seemingly paradoxically a reactor is a thousand times more likely to fail the mission while on average being ten times easier to clean up which superficially appears impossible but its actually consistent. A less reliable reactor sounds like a bad idea for a mars mission unless you have like 10-way redundancy in which case losing one isn't a biggie and we don't have the lift capacity to launch a RTG large enough. Or another fascinating engineering tradeoff, I suspect the total predicted environment damage over time of launching small reliable tested complete reactors into space would be much lower than launching individual components of RTGs and assembling a freakin' huge RTG in orbit before a mission, not to mention a reactor built on the surface MIGHT be more reliable than a RTG built in space, at least until we have substantial space infrastructure.

        Another odd reactor vs RTG issue is total activity at launch time (in case of a launcher accident). Activity of a reactor thats shutdown and hasn't been run at full power for a long time is actually ridiculously low and real reactors on earth need high-activity sticks to safely and predictably boot them up from cold start because there's not that many thermal neutrons floating around randomly. Initiators of implosion a-bombs are non-trivial design problem for same reason, how to make the thing go nuke-mode at maximum density and not too early or late is actually quite a classified puzzle. RTGs of course have both way more material and its hot hot hot no off switch active as hell at launch time. So in terms of "disintegrations per second" I suspect a brand new reactor is vastly staggeringly cleaner than a RTG. AND after long years at full power, its the other way around, RTGs have worn out and a couple half lives have gone by and they're slightly less than at launch time, but reactors are a smoking stinking ruin of almost random extremely radioactive isotopes from U-235 split in half (and some neutron activation but lets keep this simple, etc).

        • (Score: 2) by HiThere on Thursday May 03 2018, @05:40PM (5 children)

          by HiThere (866) Subscriber Badge on Thursday May 03 2018, @05:40PM (#675169) Journal

          I *think* the slug of uranium in the reactor is small enough that even without active cooling it wouldn't generate enough heat to melt. Or at least that's the way I read the summary.

          That said, a closed mechanical system makes me nervous too, but for the use case of this thing, I think that failure would just translate into "mission failure". They don't seem to be planning to use it on man-rated missions. And even if it were to melt, that would just cause it to change into a less heat-retaining shape if there were any gravity present. It's quite unlikely there would be a solvent (like water) to spread it around, and even if there were, it's only a small amount, and so heavy it wouldn't easily spread far.

          So my nervousness has more to do with mission failure than anything else. But out past the orbit of Mars there really isn't much other choice. Mirrors + solar cells could work in free-fall, but that would be more complex.

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          • (Score: 2) by dry on Friday May 04 2018, @05:15AM (4 children)

            by dry (223) on Friday May 04 2018, @05:15AM (#675507) Journal

            Eventually we will need something like this for manned missions. a Mars mission for example can't rely on solar as there are dust storms that can last months.

            • (Score: 2) by HiThere on Friday May 04 2018, @04:44PM (3 children)

              by HiThere (866) Subscriber Badge on Friday May 04 2018, @04:44PM (#675726) Journal

              Yes, but eventually isn't now, and a manned mission had better have a repair tech available.

              That said, Stirling engines are among the most reliable mechanical engines. For one thing, they can be sealed against contamination. So for the manned mission you'll need multiple generators, the ability to make parts, and the tools to open and repair individual failures. And those are going to be rare, so that can't be anybody's main job.

              This thing, though, reminds me of vacuum tube computers. Just barely good enough. What the equivalent of transistors is, though, I have no idea. As you say, solar power looks dubious. MHD hasn't ever really panned out. Etc. Of course, I could be excessively pessimistic, but moving parts wear.

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              • (Score: 2) by dry on Friday May 04 2018, @10:59PM (2 children)

                by dry (223) on Friday May 04 2018, @10:59PM (#675901) Journal

                I'd guess by the time something like this is needed for manned missions, it'll be the mark 3 or so version. As well a Mars mission is going to use a mixture of solar and nuclear and may not usually depend on the nuclear.

                • (Score: 2) by HiThere on Saturday May 05 2018, @05:57PM (1 child)

                  by HiThere (866) Subscriber Badge on Saturday May 05 2018, @05:57PM (#676097) Journal

                  Well, you need to remember that solar power falls off as the square of the distance from the sun. It's true that Mars' atmosphere is thin, and usually rather transparent, but solar power will be weaker than at earth's orbit even so.
                  earth orbit radius = 93 million miles (approx.)
                  mars orbit radius = 142 million miles (approx.)
                  93^2/142^2 = 0.43 (approx.)
                  So figure you'll need twice as many solar cells to generate a given amount of power on Mars than on Earth. This is *quite* rough, of course, but it should be in the ballpark.

                  IOW, it's quite likely that given that you're going to need nuclear power, adding the solar power wouldn't be worth it. Better to have redundant nuclear power, so if one goes down you can fix it. I just wish there were something better than a steam engine to extract the power with. OTOH, the lower average temperature on Mars should mean the steam engine is more efficient, and at least with a Stirling engine you don't need to keep replacing the working fluid.

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                  • (Score: 3, Interesting) by dry on Saturday May 05 2018, @06:26PM

                    by dry (223) on Saturday May 05 2018, @06:26PM (#676106) Journal

                    Have to consider things like power distribution. Probably going to be a shortage of wire at first and a real shortage of poles. Then there's how long it'll take the nuclear plant to come on line. Then any power needs far from camp.
                    Needing twice the solar panels as Earth isn't that bad. With lack of cloud cover and a higher flux of UV should boost that 43% up a bit.

        • (Score: 2) by choose another one on Thursday May 03 2018, @06:13PM (5 children)

          by choose another one (515) Subscriber Badge on Thursday May 03 2018, @06:13PM (#675196)

          There are other non-technical tradeoffs too:

          1. RTGs are no longer a viable option because NASA doesn't _have_ much more Plutonium (3 missions left I think), no one is making large quantities of it for weapons any more and restarting production for space exploration alone is challenging (and requires a reactor with all the disadvantages listed, albeit not on top of a rocket) - see e.g. http://spacenews.com/plutonium-supply-for-nasa-missions-faces-long-term-challenges/ [spacenews.com]

          2. At-launch activity/toxicity level of RTGs has already become a fairly large political / environmental issue

          3. For reactors, at-launch is much cleaner, and failure in deep space or on another planet is a _mission_ problem, but not a political / environmental issue - yes, the reactor is a smoking stinking ruin of almost random extremely radioactive isotopes, but by that time it is in deep space or at worst it is on the moon/mars, and hardly anyone gives a shit, really. The _only_ issue would be if there is a live reactor on a sample-return mission or an earth-slingshot, which isn't proposed and probably wouldn't fly for exactly that reason...

          So, yeah the tradeoff is exactly as you describe, IF we (well NASA) had plenty more Pu, AND was intending to stick reactors in earth-return missions.

          • (Score: 2) by JoeMerchant on Thursday May 03 2018, @09:33PM (4 children)

            by JoeMerchant (3937) on Thursday May 03 2018, @09:33PM (#675327)

            NASA doesn't _have_ much more Plutonium

            The French could fix that for you, they're not afraid of breeders.

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            • (Score: 2) by dry on Friday May 04 2018, @05:23AM (1 child)

              by dry (223) on Friday May 04 2018, @05:23AM (#675510) Journal

              The problem is that Pu-238 is harder to make/separate and if IRC needs more then a simple breeder reactor. Basically neutron irradiation of neptunium-237 or Americium.

              • (Score: 2) by JoeMerchant on Friday May 04 2018, @03:04PM

                by JoeMerchant (3937) on Friday May 04 2018, @03:04PM (#675689)

                We, the French, the Canadians (probably not the French Canadians), and many other countries have had the technology for over 50 years. What we lack is the will to use it.

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            • (Score: 2) by VLM on Friday May 04 2018, @03:13PM (1 child)

              by VLM (445) Subscriber Badge on Friday May 04 2018, @03:13PM (#675694)

              One of the plutonium isotopes is literally thermally hot in bulk which makes for crappy bombs because of fizzle danger (self triggered at the wrong instant resulting in bad yields) and great RTGs, the other isotope is the opposite. So you need a military bomb focused breeder program along with a bomb-focused processing plant.

              You can make a-bombs that are not isotopically clean, they just work better if cleaned up (much hand waving about engineering effort vs manufacturing effort removed). Likewise already big RTGs would be immense if they used mixed or a-bomb grade Pu.

              AFAIK the French are not into RTG generation but thats political and has varied from decade to decade.

              • (Score: 2) by JoeMerchant on Friday May 04 2018, @04:02PM

                by JoeMerchant (3937) on Friday May 04 2018, @04:02PM (#675708)

                AFAIK the French are not into RTG generation but thats political and has varied from decade to decade.

                It is all VERY political, and has been from the beginning.

                I'd like to see the US take a Space 1999-esque style leadership role on the moon - build breeder reactors there, preferably not on the "dark side", and keep them open from day 1 for true international inspection and verification of activities. Load the "bad" isotopes on rockets to the sun (WCGW?), and distribute/sell the good ones for the betterment of mankind. I know, the 1999 plot was just a waste dump, and this one would require full-court-press to be running by 2099, but it seems like a good use for the real-estate, and I'd rather put the resources into something like that than bashing each other for control of the remaining oil reserves.

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    • (Score: 2, Interesting) by suburbanitemediocrity on Thursday May 03 2018, @01:34PM (4 children)

      by suburbanitemediocrity (6844) on Thursday May 03 2018, @01:34PM (#675039)

      " For what definitions of "safe" and "handle"?"

      It used to be used as a color in glazing for ceramic plates. It's not very radioactive, but if you wanted to kill a bunch of people with it, it would be more effective to dump it in the water supply as it is very poisonous.

      • (Score: 2, Offtopic) by realDonaldTrump on Thursday May 03 2018, @01:49PM (3 children)

        by realDonaldTrump (6614) on Thursday May 03 2018, @01:49PM (#675046) Homepage Journal

        It's very safe -- so long as we keep Crooked Hillary away from it. (Uranium One) We used to use it in our nuclear arsenal -- our nuclear arsenal has always been the safest in the world. And it is far stronger and more powerful than ever before!!!

    • (Score: 4, Informative) by takyon on Thursday May 03 2018, @01:39PM (3 children)

      by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Thursday May 03 2018, @01:39PM (#675041) Journal

      Really? For what definitions of "safe" and "handle"?

      Worst case scenario for mission planners is that the spacecraft blows up before reaching orbit, spreading nuclear material everywhere. But the uranium scattering is not as bad as an RTG:

      https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator#Radioactive_contamination [wikipedia.org]

      The plutonium-238 used in these RTGs has a half-life of 87.74 years, in contrast to the 24,110 year half-life of plutonium-239 used in nuclear weapons and reactors. A consequence of the shorter half-life is that plutonium-238 is about 275 times more radioactive than plutonium-239 (i.e. 17.3 curies (640 GBq)/g compared to 0.063 curies (2.3 GBq)/g). For instance, 3.6 kg of plutonium-238 undergoes the same number of radioactive decays per second as 1 tonne of plutonium-239. Since the morbidity of the two isotopes in terms of absorbed radioactivity is almost exactly the same,[32] plutonium-238 is around 275 times more toxic by weight than plutonium-239.

      The alpha radiation emitted by either isotope will not penetrate the skin, but it can irradiate internal organs if plutonium is inhaled or ingested. Particularly at risk is the skeleton, the surface of which is likely to absorb the isotope, and the liver, where the isotope will collect and become concentrated.

      https://en.wikipedia.org/wiki/Plutonium-238 [wikipedia.org]

      One gram of 238Pu corresponds to 1/238 moles, which is 2.53×1021 plutonium atoms. Considering its half-life t1/2 = 87.7 years, its activity is

      [formula omitted]

      A is the number of 238Pu decays per second per gram (634 billion). Each of the emitted alpha particles has kinetic energy 5.593 MeV or 8.96×10−13 J which is quickly converted to heat when the particle decelerates in the material. Therefore each gram of 238Pu spontaneously generates 0.568 W of heat.

      https://en.wikipedia.org/wiki/Uranium-235 [wikipedia.org]

      Uranium-235 has a half-life of 703.8 million years.

      It's a similar story for other 238Pu replacements, such as Americium-241 with a half life of 432 years.

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      • (Score: 3, Insightful) by sgleysti on Thursday May 03 2018, @02:01PM (2 children)

        by sgleysti (56) Subscriber Badge on Thursday May 03 2018, @02:01PM (#675053)

        What I can't figure out from the articles: Is this thing a souped up RTG that converts the decay heat of a block of U-235 to electricity with Stirling engines? Or is it a reactor with neutron reflectors/moderators/etc. that uses Stirling engines instead of steam turbines?

        The former seems most likely, although they keep calling it a reactor. And I suppose it is in some sense.

        • (Score: 2) by takyon on Thursday May 03 2018, @02:12PM

          by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Thursday May 03 2018, @02:12PM (#675059) Journal

          It's a genuine™ nuclear fission reactor that uses the Stirling engines to convert heat into electricity. In the video they show you where the boron carbide control rod is.

          This PDF also has some diagrams:

          https://www.nasa.gov/sites/default/files/atoms/files/kilopower-media-event-charts-final-011618.pdf [nasa.gov]

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        • (Score: 2) by VLM on Thursday May 03 2018, @02:27PM

          by VLM (445) Subscriber Badge on Thursday May 03 2018, @02:27PM (#675071)

          They're technically distinct and always described incorrectly as one.

          Part one is the heat source which can be a RTG that has no off switch and is large and heavy and low power and almost infinitely reliable and safe for re-entry, or a fission reactor which is controllable and unreliable and dangerous as heck.

          Part two is the thing that turns a pile of hot heat into colder heat squirting out electricity. There are large heavy inefficient no moving part Peltier-like devices, and there's traditional engineering plant stuff like turbines or slightly more obscure like stirling engine tech.

          Technically there's no reason you couldn't stick a nice no-moving parts chunk of the "bad" plutonium isotope up against a turbine, or bolt a Peltier-like thermoelectric no moving parts generator up to a reactor, although in practice nobodies ever done it for realsies. Might make an interesting detail for a sci fi story.

          As I think about it, hopefully this isn't some bullshit classified stuff from half a century ago, an old fashioned 40s era plutonium production (as opposed to electricity production) plant technically could use a no-moving parts thermoelectric generator to have a ridiculously reliable source of cooling fan air. Sure they're not efficient but no moving parts is cheap and reliable and even in the 40s it should have generated "enough" power to run the cooling fans. Oh shit I hear black helicopters arriving as I type this best hit Submit while I still ca

    • (Score: 2) by Azuma Hazuki on Thursday May 03 2018, @07:11PM (1 child)

      by Azuma Hazuki (5086) on Thursday May 03 2018, @07:11PM (#675240) Journal

      In theory, any subcritical mass of fissile material is "safe to handle" so long as you have the necessary radiation protection. It's when you get too much fissile material together in one place that nuclear hellfire breaks loose...look up the Demon Core on wiki for an instructive example (*shudder*).

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      • (Score: 2) by JoeMerchant on Thursday May 03 2018, @09:46PM

        by JoeMerchant (3937) on Thursday May 03 2018, @09:46PM (#675339)

        Ah, so "safe to handle" when covered in a lead suit and you don't stay near it for more than a short period of time... yeah, totally safe.

        Side stories:

        In 1988 I met a man whose father worked at Savannah River during the Cold War doing Hot laundry. Dad always wore his dosimeter, followed all the rules, never had an overexposure or accident (at least not that anyone talked about), and the facility took real good care of his wife when he passed away at the ripe old age of 43.

        In 2006 I interviewed for a job at an isotope facility, they kept a hot pile behind a maze and of course always meticulously followed all the safety procedures. The position was open because the 52 year old director of engineering had died recently, of cancer.

        In 2007 I knew a graduate student who did his Masters' thesis on dose measuring devices, mostly in Linac radiotherapy machines ("safe" when off, like an X-ray), and a little around cobalt sources. Not only was he highly trained in all the safety procedures, he was developing methods to better measure dose and improve the safety and therapeutic dose measurements. Died in his early 20s of a rare form of blood cancer, no history of cancer in his family.

        Myself, I have done extensive MRI safety work in and around the bore while scanning is active, I also sat for a couple hours of MRI scanning of myself to help gather reference datasets for our work. All in all, I prefer, and trust, non-ionizing radiation much more than the glow-in-the-dark variety.

        --
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  • (Score: 2, Funny) by suburbanitemediocrity on Thursday May 03 2018, @01:26PM (5 children)

    by suburbanitemediocrity (6844) on Thursday May 03 2018, @01:26PM (#675035)

    and have them mass produce these things for ebay at $500 a pop.

    • (Score: 3, Insightful) by VLM on Thursday May 03 2018, @02:19PM (4 children)

      by VLM (445) Subscriber Badge on Thursday May 03 2018, @02:19PM (#675065)

      We've already done the first part (snicker snicker).

      The only countries on the planet to ever have invented nukes are AFAIK the USA and South Africa. Everyone else spies and steals. There is some local engineering of course such that Russian nuclear products (both power and exploding) are distinctly different while still being hillbilly knock offs from the USA family tree of white male nuclear technology.

      I recently had an amusing discussion with an ex-coworker along the lines of that chick who culturally appropriated a Chinese dress for prom should have asked for the Chinese to stop culturally appropriating white male computer networks, white male electronics, white male nuclear power, white male medical technology, white male science in general, white male invented social media, etc, and then she'd give back the Chinese dress. The reason she hasn't gone after the Chinese that way, is the only people annoyed with her are the usual suspects, white superiority complex leftists, actual Chinese are pretty chill WRT some hot-ish USA chick rockin' "their" dress.

      • (Score: 0) by Anonymous Coward on Thursday May 03 2018, @04:45PM (3 children)

        by Anonymous Coward on Thursday May 03 2018, @04:45PM (#675139)

        The only countries on the planet to ever have invented nukes are AFAIK the USA and South Africa.

        Cough...Israel...Cough...

        • (Score: 2) by bob_super on Thursday May 03 2018, @05:02PM (2 children)

          by bob_super (1357) on Thursday May 03 2018, @05:02PM (#675148)

          Definitely not Israel. They got their plans from the US.

          France, maybe ? The USG at the time wasn't eager to see France with nukes.
          India ?

          • (Score: 0) by Anonymous Coward on Thursday May 03 2018, @08:02PM (1 child)

            by Anonymous Coward on Thursday May 03 2018, @08:02PM (#675275)

            copied from Wikipedia [wikipedia.org]:

            France was one of the nuclear pioneers, going back to the work of Marie Skłodowska Curie. Curie’s last assistant Bertrand Goldschmidt became the father of the French Bomb. ...

            ... the first French reactor went critical in 1948 and small amounts of plutonium were extracted in 1949. ...
            ... from 1949 Israeli scientists were invited to the Saclay Nuclear Research Centre, this cooperation leading to a joint effort including sharing of knowledge between French and Israeli scientists especially those with knowledge from the Manhattan Project, the French believed that cooperation with Israel could give them access to international Jewish nuclear scientists. ...

            ...

            The United States began providing technical assistance to the French program in the early 1970s through the 1980s. The aid was secret ... The Nixon administration, unlike previous presidencies, did not oppose its allies' possession of atomic weapons and believed that the Soviets would find having multiple nuclear-armed Western opponents more difficult. Because the Atomic Energy Act of 1946 prohibited sharing information on nuclear weapon design, a method known as "negative guidance" or "Twenty Questions" was used; French scientists described to their American counterparts their research, and were told whether they were correct. Areas in which the French received help included MIRV, radiation hardening, missile design, intelligence on Soviet anti-missile defences, and advanced computer technology.

            • (Score: 2) by bob_super on Thursday May 03 2018, @08:52PM

              by bob_super (1357) on Thursday May 03 2018, @08:52PM (#675302)

              Check your dates
              French A bomb: February 1960
              French H bomb: August 1968

  • (Score: 3, Interesting) by richtopia on Thursday May 03 2018, @04:22PM (4 children)

    by richtopia (3160) on Thursday May 03 2018, @04:22PM (#675134) Homepage Journal

    I could see a massive interest in this reactor for submarines, assuming sufficient shielding is in-place for humans to safely function nearby (the Wikipedia article says a beryllium oxide reflector is used to protect electronics from gamma radiation). From the rest of the description the reactor is passive, with the only moving parts being the stirling engine.

    Nuclear submarines today have an issue that you cannot shut down the reactor to be silent; the noise signature of cooling pumps is small but modern sonar can identify it. This has inspired research into alternative air-independent propulsion systems, with one of the most famous examples being Sweden's Gotland class submarine (https://en.wikipedia.org/wiki/Gotland-class_submarine). This submarine uses a 75kW stirling engine and has been very successful in wargaming thanks to the silent propulsion system, scoring "hits" on other submarines and an aircraft carrier. Now NASA's 10kW reactor is a long way off from 75kW, but the heat pipe technology could be very useful for larger applications too.

    • (Score: 2) by HiThere on Thursday May 03 2018, @05:42PM (2 children)

      by HiThere (866) Subscriber Badge on Thursday May 03 2018, @05:42PM (#675171) Journal

      I think this doesn't produce enough power for submarines. Perhaps submarine drones, though...

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      • (Score: 2) by PiMuNu on Friday May 04 2018, @01:15PM (1 child)

        by PiMuNu (3823) on Friday May 04 2018, @01:15PM (#675630)

        I think submarine drones dont work unless they are fully autonomous. You can't get enough penetration depth with any conventional comms.

        • (Score: 2) by HiThere on Friday May 04 2018, @04:56PM

          by HiThere (866) Subscriber Badge on Friday May 04 2018, @04:56PM (#675733) Journal

          Well, you don't need full autonomy, but you need it to be pretty autonomous, as the communications channels that work have a low bit rate. Even if they didn't, you wouldn't want to automatically reveal your position. So say as autonomous as a Tesla autopilot, or maybe a bit more (and a bit less in other ways: you don't need to worry about pedestrians). IOW, doable, but not easy, and not cheap.

          Still, there are missions for which such devices would be ideal, such as a dynamic sensor net. These would be too expensive to really be considered expendable in normal use, but could be used as highly targeted weapons if need be, where the dispatcher is at an unknowable location. (Well, somewhere within a few hundred miles.)

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    • (Score: 2) by captain_nifty on Thursday May 03 2018, @10:41PM

      by captain_nifty (4252) on Thursday May 03 2018, @10:41PM (#675371)

      liquid sodium + water = a bad day for everyone.

      Liquid sodium reactors have been researched and tested, but it has always ended badly. Space might be better, but most everywhere on earth has a lot of water.

  • (Score: 0) by Anonymous Coward on Thursday May 03 2018, @08:09PM

    by Anonymous Coward on Thursday May 03 2018, @08:09PM (#675279)

    Imagine a Beowulf cluster of these!

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