7 ms·

Could this be used to create a nuclear power generator without moving parts? Some radioactive material in the center, some coating to absorb the radiation, and

Could this be used to create a nuclear power generator without moving parts? Some radioactive material in the center, some coating to absorb the radiation, and a shell of these cells to generate electricity.

rkagerer 3y ago
Are there already solid state ones that use the heat from radioactive decay and the Peltier principle? I assume your idea, if feasible, might be more efficient?
- 20after4 3y ago
  Yes they exist, though I don't think they are Peltier devices: https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...
  - brucethemoose2 3y ago
    If you want a "zero moving part reactor," what you are really looking for is: https://en.m.wikipedia.org/wiki/Fission_fragment_reactor https://en.m.wikipedia.org/wiki/Fission_fragment_reactor And its spaceflight cousin: https://www.projectrho.com/public_html/rocket/enginelist2.php#id--Nuclear_Thermal--Fission_Fragment_Type https://www.projectrho.com/public_html/rocket/enginelist2.ph... Though they are not peltier devices either.
deleted 3y ago
[deleted]
fsh 3y ago
There are betavoltaic generators [1] that directly produce electricity from decay electrons using p-n junctions (similar to photovoltaic cells). However, in the vast majority of applications, they get outperformed by modern lithium batteries (i.e. coin cells). [1] https://en.m.wikipedia.org/wiki/Betavoltaic_device https://en.m.wikipedia.org/wiki/Betavoltaic_device
- throwaway20304 3y ago
  How can you compare a generator to a battery? How do you charge the battery without a generator?
  - spoiler 3y ago
    A bettery, from the viewpoint of a circuit, is just another source. So we could call them chemical electricity generators, if we're brave enough to indulge the confusion
    - throwaway20304 3y ago
      I still don't quite understand it. Where does the battery get the energy? I understand that there's no difference in a circuit, but why is this comparison relevant? Many power sources are way less efficient that using a battery, but we need to charge the battery.
      - QuarterReptile 3y ago
        For low-enough-power applications and sufficiently long-lasting batteries, charging is just another step in production.
      - fsh 3y ago
        Betavotaic generators usually produce extremely low power. A similarly sized battery can last for decades at the same power output.
      - regularfry 3y ago
        Alkaline batteries are never charged, per se. The energy comes from the one-way chemical breakdown of cathode and the anode.
  - dukeyukey 3y ago
    Betavoltaics aren't really either - they provide a constant, slowly-over-years declining flow of power. They can't be recharged, they _could_ be refueled (don't know if it's economic though), and are mostly used when you need a small flow of power and a long period of time between maintenance (think pacemakers, weather buoys, some satellites or probes).
goodpoint 3y ago
We already have a fusion reactor at a relatively safe distance called the sun.
- svantana 3y ago
  This looks like it has about 100x higher power density than what solar PV gives at peak. Combine that with 100% uptime and deployment pretty much anywhere, that are some pretty compelling advantages.
  - hedora 3y ago
    How could that possibly be the case? The current best commercially-available solar panels are 20% efficient. Last-gen stuff is 10-15%.
    - jjk166 3y ago
      Well if you put those solar panels right up against the sun, they'd be much more power dense. But for the moment building a nuclear reactor on earth is a significantly easier engineering challenge than building a solar plant on the sun.
- kgabis 3y ago
  We also have this thing called night, as well as weather and seasons.
  - awestroke 3y ago
    And we also have this looming thing called climate emergency, which should conceivably motivate us to forge ahead with renewables and adjust our energy usage patterns to match production peaks, lest we doom humanity to extinction
    - badtension 3y ago
      I feel like this is one of the biggest missed opportunities. Why do we insist on our energy system to be infinitely flexible and full power available 24/7? Is a habit of doing the laundry at night worth more than additional millions of tons of CO2 in the atmosphere? I understand convenience, laziness and inertia (resisting change) but I also think changing the times when we click "power on" is a simpler solution than mining millions of tons of more lithium, no?
Dennip 3y ago
Isn't the thing running the Voyager space probe one of these? https://en.wikipedia.org/wiki/Voyager_2#Power https://en.wikipedia.org/wiki/Voyager_2#Power
perihelions 3y ago
Sure, on paper. One of the proposed ideas for nuclear rocket propulsion would contain a fissioning gas cloud inside a fused-silica glass blub. At a temperature of several thousand degrees (5,000 - 20,000 K), incandescent light escapes the glass, and gets absorbed by the hydrogen propellant (with bits of solid dust flowing through it as an opacifier). That's one-half of your idea: there's no photovoltaic component, but it does examine the "nuclear fission reactor as an optical light source" half. https://en.wikipedia.org/wiki/Nuclear_lightbulb https://en.wikipedia.org/wiki/Nuclear_lightbulb https://sci-hub.se/10.2514/6.1991-3512 https://sci-hub.se/10.2514/6.1991-3512 (pdf) ("Summary of nuclear light bulb development status" (1991)) excerpt: - "The gas core Nuclear Light Bulb (NLB) propulsion system could provide both the desired thrust and specific impulse. Initial gas core nuclear rocket (GCNR) investigations started in the 1950s when two somewhat different concepts emerged; an open-cycle GCNR and a closed-cycle GCNR (named the Nuclear Light Bulb). The open cycle configuration (Fig. 1) isolates hot fissioning gas from the chamber walls by flowing cooler propellant around the hot gas. Although some nuclear fuel will diffuse into the propellant and exhaust into space, the theoretical amount was considered too small to be of consequence. NASA-Lewis pursued the open cycle by both analysis and laboratory experiments from the ’50s through the early ‘70s.’" - "At the same time, United Technologies Research Center, then United Aircraft Research Laboratory, explored the closed cycle NLB concept (Fig. 2).[2,3] Hot fissioning fuel in a gaseous state is confined within a transparent wall of fused silica by a vortex of tangentially injected buffer gas that is also transparent to thermal radiation. Hydrogen propellant, seeded with micron-size tungsten particles to absorb the thermal radiation from the hot fuel, flows axially outside the fused silica wall and is exhausted through thrust nozzles. Complete fuel containment requires continuous withdrawal of a small fraction of the mixture of fuel and buffer gas for reprocessing and reinjection into the vortex flow."
discordance 3y ago
Yeah, that’s a radioisotope thermoelectric generator: https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_generator https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_... There’s a story about some loggers finding an abandoned RTG in Siberia and sleeping next to it for warmth. They woke up with severe radiation burns.
- rich_sasha 3y ago
  That's different, isn't it? An RTG only produces heat via radioactive decay. A nuclear reactor is a controlled chain reaction.
  - mcpackieh 3y ago
    Yes, those aren't nuclear reactors. However nuclear reactors with thermoelectric converters for power generation have been built before. There were the Soviet TOPAZ reactors and the US SNAP-10A reactor.
- shepherdjerred 3y ago
  You'll find a similar story (minus the burns) in The Martian! https://www.amazon.com/Martian-Andy-Weir/dp/0553418025 https://www.amazon.com/Martian-Andy-Weir/dp/0553418025
lambdatronics 3y ago
No-moving-parts is probably not realistic - the core would be much hotter than the radiating surface due to the thermal resistance of the shielding. More likely, you would have a working fluid to transfer the heat. Most nuclear reactors operate at much lower temperatures where TPV wouldn't be efficient or cost-effective. It's certainly possible to go much higher. Nuclear-thermal rocket propulsion tests ran with exhaust temperatures up to ~2200 C [0]. Whatever fluid is used, you would need to avoid radioactivity in it, b/c that would probably degrade the TPV. Also you would probably want to avoid having heat exchangers because each one incurs a temperature drop. So helium would fit that bill. That's what the "high temperature gas reactors" use [1]. IDK if helium-compatible plumbing/pumping could be made to work at >2000 C though. Edit: BTW, there are radioisotope thermoelectric generators used for space applications primarily, but they are not true nuclear reactors - they produce short-range radiation that doesn't require much shielding. Nuclear reactors produce neutrons and gammas that require thick shielding. [0] https://en.wikipedia.org/wiki/Project_Rover#Kiwi_A https://en.wikipedia.org/wiki/Project_Rover#Kiwi_A [1] https://en.wikipedia.org/wiki/High-temperature_gas_reactor https://en.wikipedia.org/wiki/High-temperature_gas_reactor

rkagerer 3y ago

Are there already solid state ones that use the heat from radioactive decay and the Peltier principle? I assume your idea, if feasible, might be more efficient?

20after4 3y ago
Yes they exist, though I don't think they are Peltier devices: https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...
- brucethemoose2 3y ago
  If you want a "zero moving part reactor," what you are really looking for is: https://en.m.wikipedia.org/wiki/Fission_fragment_reactor https://en.m.wikipedia.org/wiki/Fission_fragment_reactor And its spaceflight cousin: https://www.projectrho.com/public_html/rocket/enginelist2.php#id--Nuclear_Thermal--Fission_Fragment_Type https://www.projectrho.com/public_html/rocket/enginelist2.ph... Though they are not peltier devices either.

deleted 3y ago

[deleted]

fsh 3y ago

There are betavoltaic generators [1] that directly produce electricity from decay electrons using p-n junctions (similar to photovoltaic cells). However, in the vast majority of applications, they get outperformed by modern lithium batteries (i.e. coin cells). [1] https://en.m.wikipedia.org/wiki/Betavoltaic_device https://en.m.wikipedia.org/wiki/Betavoltaic_device

throwaway20304 3y ago
How can you compare a generator to a battery? How do you charge the battery without a generator?
- spoiler 3y ago
  A bettery, from the viewpoint of a circuit, is just another source. So we could call them chemical electricity generators, if we're brave enough to indulge the confusion
  - throwaway20304 3y ago
    I still don't quite understand it. Where does the battery get the energy? I understand that there's no difference in a circuit, but why is this comparison relevant? Many power sources are way less efficient that using a battery, but we need to charge the battery.
    - QuarterReptile 3y ago
      For low-enough-power applications and sufficiently long-lasting batteries, charging is just another step in production.
    - fsh 3y ago
      Betavotaic generators usually produce extremely low power. A similarly sized battery can last for decades at the same power output.
    - regularfry 3y ago
      Alkaline batteries are never charged, per se. The energy comes from the one-way chemical breakdown of cathode and the anode.
- dukeyukey 3y ago
  Betavoltaics aren't really either - they provide a constant, slowly-over-years declining flow of power. They can't be recharged, they _could_ be refueled (don't know if it's economic though), and are mostly used when you need a small flow of power and a long period of time between maintenance (think pacemakers, weather buoys, some satellites or probes).

goodpoint 3y ago

We already have a fusion reactor at a relatively safe distance called the sun.

svantana 3y ago
This looks like it has about 100x higher power density than what solar PV gives at peak. Combine that with 100% uptime and deployment pretty much anywhere, that are some pretty compelling advantages.
- hedora 3y ago
  How could that possibly be the case? The current best commercially-available solar panels are 20% efficient. Last-gen stuff is 10-15%.
  - jjk166 3y ago
    Well if you put those solar panels right up against the sun, they'd be much more power dense. But for the moment building a nuclear reactor on earth is a significantly easier engineering challenge than building a solar plant on the sun.
kgabis 3y ago
We also have this thing called night, as well as weather and seasons.
- awestroke 3y ago
  And we also have this looming thing called climate emergency, which should conceivably motivate us to forge ahead with renewables and adjust our energy usage patterns to match production peaks, lest we doom humanity to extinction
  - badtension 3y ago
    I feel like this is one of the biggest missed opportunities. Why do we insist on our energy system to be infinitely flexible and full power available 24/7? Is a habit of doing the laundry at night worth more than additional millions of tons of CO2 in the atmosphere? I understand convenience, laziness and inertia (resisting change) but I also think changing the times when we click "power on" is a simpler solution than mining millions of tons of more lithium, no?

Dennip 3y ago

Isn't the thing running the Voyager space probe one of these? https://en.wikipedia.org/wiki/Voyager_2#Power https://en.wikipedia.org/wiki/Voyager_2#Power

perihelions 3y ago

Sure, on paper. One of the proposed ideas for nuclear rocket propulsion would contain a fissioning gas cloud inside a fused-silica glass blub. At a temperature of several thousand degrees (5,000 - 20,000 K), incandescent light escapes the glass, and gets absorbed by the hydrogen propellant (with bits of solid dust flowing through it as an opacifier). That's one-half of your idea: there's no photovoltaic component, but it does examine the "nuclear fission reactor as an optical light source" half. https://en.wikipedia.org/wiki/Nuclear_lightbulb https://en.wikipedia.org/wiki/Nuclear_lightbulb https://sci-hub.se/10.2514/6.1991-3512 https://sci-hub.se/10.2514/6.1991-3512 (pdf) ("Summary of nuclear light bulb development status" (1991)) excerpt: - "The gas core Nuclear Light Bulb (NLB) propulsion system could provide both the desired thrust and specific impulse. Initial gas core nuclear rocket (GCNR) investigations started in the 1950s when two somewhat different concepts emerged; an open-cycle GCNR and a closed-cycle GCNR (named the Nuclear Light Bulb). The open cycle configuration (Fig. 1) isolates hot fissioning gas from the chamber walls by flowing cooler propellant around the hot gas. Although some nuclear fuel will diffuse into the propellant and exhaust into space, the theoretical amount was considered too small to be of consequence. NASA-Lewis pursued the open cycle by both analysis and laboratory experiments from the ’50s through the early ‘70s.’" - "At the same time, United Technologies Research Center, then United Aircraft Research Laboratory, explored the closed cycle NLB concept (Fig. 2).[2,3] Hot fissioning fuel in a gaseous state is confined within a transparent wall of fused silica by a vortex of tangentially injected buffer gas that is also transparent to thermal radiation. Hydrogen propellant, seeded with micron-size tungsten particles to absorb the thermal radiation from the hot fuel, flows axially outside the fused silica wall and is exhausted through thrust nozzles. Complete fuel containment requires continuous withdrawal of a small fraction of the mixture of fuel and buffer gas for reprocessing and reinjection into the vortex flow."

discordance 3y ago

Yeah, that’s a radioisotope thermoelectric generator: https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_generator https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_... There’s a story about some loggers finding an abandoned RTG in Siberia and sleeping next to it for warmth. They woke up with severe radiation burns.

rich_sasha 3y ago
That's different, isn't it? An RTG only produces heat via radioactive decay. A nuclear reactor is a controlled chain reaction.
- mcpackieh 3y ago
  Yes, those aren't nuclear reactors. However nuclear reactors with thermoelectric converters for power generation have been built before. There were the Soviet TOPAZ reactors and the US SNAP-10A reactor.
shepherdjerred 3y ago
You'll find a similar story (minus the burns) in The Martian! https://www.amazon.com/Martian-Andy-Weir/dp/0553418025 https://www.amazon.com/Martian-Andy-Weir/dp/0553418025

lambdatronics 3y ago

No-moving-parts is probably not realistic - the core would be much hotter than the radiating surface due to the thermal resistance of the shielding. More likely, you would have a working fluid to transfer the heat. Most nuclear reactors operate at much lower temperatures where TPV wouldn't be efficient or cost-effective. It's certainly possible to go much higher. Nuclear-thermal rocket propulsion tests ran with exhaust temperatures up to ~2200 C [0]. Whatever fluid is used, you would need to avoid radioactivity in it, b/c that would probably degrade the TPV. Also you would probably want to avoid having heat exchangers because each one incurs a temperature drop. So helium would fit that bill. That's what the "high temperature gas reactors" use [1]. IDK if helium-compatible plumbing/pumping could be made to work at >2000 C though. Edit: BTW, there are radioisotope thermoelectric generators used for space applications primarily, but they are not true nuclear reactors - they produce short-range radiation that doesn't require much shielding. Nuclear reactors produce neutrons and gammas that require thick shielding. [0] https://en.wikipedia.org/wiki/Project_Rover#Kiwi_A https://en.wikipedia.org/wiki/Project_Rover#Kiwi_A [1] https://en.wikipedia.org/wiki/High-temperature_gas_reactor https://en.wikipedia.org/wiki/High-temperature_gas_reactor