20 ms·

Traveling Wave Reactor

76 points by jonbaer 7y ago

zamadatix 7y ago
After watching the Bill Gates Netflix documentary I was wondering what HN would think of the nuclear safety debate in regards to TerraPower's traveling wave design.
- cagenut 7y ago
  I am very wishful but its still stuck in the wishful thinking phase. Obviously the 'trade war' derailing it is a travesty, but I think its important at this point (post SR15) to recognize that wishful thinking for future tech is a form of soft/self-delusional climate change denialism. The graphs are very stark at this point. We need to turn the corner on emissions in 2020/2021. That means anything still in the R&D phase is not going to be part of the first decade of the solution. This is basic project management not even an opinion on nuclear safety/proliferation.
  - DennisP 7y ago
    Yes, but if you believe that going from our current level of wind/solar to 80% wind/solar is a lot easier per gigawatt than going from 80% to 100%, then it still makes sense to develop advanced nuclear for the last part, while still rolling out wind/solar as fast as possible right now. Not to mention, fast reactors like the TWR can destroy the nuclear waste that people claim to be so worried about.
    - bassman9000 7y ago
      And they are not the only kind of reactors than can. Fast breeders can too, as well as MSR, while producing usable isotopes (e.g. medical). Waste is a solvable problem.
    - baq 7y ago
      Solar has a really bad eroi problem and I say it as an enthusiast and an owner of a microinstallation on my roof. New nuclear is absolutely necessary but it just can’t come online for a million reasons.
      - the8472 7y ago
        Some countries manage better than others. Perhaps they'll profit from electricity or hydrogen exports in the future. https://pris.iaea.org/PRIS/WorldStatistics/UnderConstructionReactorsByCountry.aspx https://pris.iaea.org/PRIS/WorldStatistics/UnderConstruction...
      - choeger 7y ago
        Eroi is a red herring. The question should be energy returned on manual labor.
        TeMPOraL 7y ago
        How is EROI a red herring? Energy returned on manual labor may be interesting wrt. profitability, but EROI is literally whether there's any sense of doing it in the first place.
        choeger 7y ago
        The thing is: if you can output (through highly automated processes) a device that yields even just 1% more energy than it required in production over its lifetime, you have the opportunity for an exponential growth in energy production at your hands. Higher EROI might indicate a steeper growth, but you can achieve the same by just scaling up production.
      - pfdietz 7y ago
        EROI of solar is just fine. The notion that it's not is based on well-debunked flawed studies.
      - ZeroGravitas 7y ago
        Solar has a good, and continually rising, eroi. But eroi isn't really a particularly useful metric: http://bountifulenergy.blogspot.com/2018/10/reports-of-low-eroi-for-solar-power-are.html?m=1 http://bountifulenergy.blogspot.com/2018/10/reports-of-low-e...
- james_s_tayler 7y ago
  My theory is the documentary was actually a 3 hour commercial for the Traveling Wave Reactor.
chkaloon 7y ago
Looking at TerraPower's website, they're talking about a prototype by the mid-2020s, and they've already been working for 11 years. Would be nice to see this sped up. The Manhattan Project lasted only 4 years. We spend much more time on the ethical, safety, and proliferation considerations than we did back then, of course, and with good reason. But I wonder if this project could use a little Elon Musk hell-or-high-water drive to move it along. I'll probably get down-voted for that, but seems like a discussion worth having.
- DennisP 7y ago
  In the early days of nuclear power we got things done a lot faster. Now in the U.S. the government makes things unnecessarily difficult; the NRC requires a couple hundred million dollars worth of design work before they'll even take a look at a new reactor. Then they give a flat yes or no, and if it's no then you're out of business. You're pretty much forced to do a big design up front; you can't do a series of experiments and adjust as you go. Things are different in Canada, and that's why reactor startups like Terrestrial Energy are making good progress there. But the U.S. DOE has a lot of infrastructure that could really help.
- mikeyouse 7y ago
  The Manhattan Project also cost something like $40 billion in today's dollars and had the benefit of conscripting some of the most brilliant minds in the world (including many Europeans who fled the war) to work on it for modest salaries.
  - sib 7y ago
    It sounds like a lot to me, but it's worth noting that there are individuals with more money than that (and certainly plenty of tech companies who could invest that much). The Gates Foundation alone could fund that investment.
- Reedx 7y ago
  It's shocking to me that the best solution we have for climate change gets downvoted on a site that's generally pro-science. But it seems to happen with every discussion about nuclear energy. Also surprising how even Bill Gates gets ignored on this issue. He's talked repeatedly about why nuclear[1][2][3], yet doesn't get a lot of traction. 1. https://www.gatesnotes.com/About-Bill-Gates/Year-in-Review-2018 https://www.gatesnotes.com/About-Bill-Gates/Year-in-Review-2... 2. https://youtu.be/d1EB1zsxW0k?t=520 https://youtu.be/d1EB1zsxW0k?t=520 3. https://ourworldindata.org/what-is-the-safest-form-of-energy https://ourworldindata.org/what-is-the-safest-form-of-energy
baybal2 7y ago
An alternative: mix californium and natural uranium and you get a solid state subcritical reactor with no need for regulation. Though, there will be no way to turn it off until Cf burns out.
- rbanffy 7y ago
  I am sure the use of Californium will also generate some extreme NIMBY.
- pfdietz 7y ago
  This is a completely terrible idea. Let's suppose we have a just barely subcritical reactor with k = .99. Then, you're going to need about 1% Cf in the core to sustain a chain reaction. The core of a 1 GW reactor contains about 100 tonnes of fuel, and fissions maybe a tonne of fuel per GW(e)-year. So, at k = .99, it would consume 10 kg of Cf per year. At current market prices this would cost $270 B/year, assuming even that much Cf were available. It would be BY FAR cheaper to provide the neutrons to drive a subcritical reactor by means of an accelerator, rather than with californium. 1 GeV protons on a uranium target will produce about 60 neutrons per proton, from spallation and fast fission. This sort of scheme has been repeatedly investigated, but has no sufficient advantage over conventional reactors to justify the extra cost and complexity.
  - baybal2 7y ago
    Hmm, I think you have a miscalculation about neutronics here, and fission/capture ratios. Cf neutrons are in their majority come nicely in 1MeV-2MeV, so you have much more fission going per neutron, and much less thermal neutron captures. If you have an intense neutron emitter dispersed in fuel + moderation + reflectors you should be able to go with much lower k to generate a meaningful amount of power. You should me able to go down to single grams of Cf per megawatt. Yes, not that economical, but at least possible for things like reactors for space use and such. At that price, that will be cheaper than current RTG material. Correct me if I am wrong.
    - pfdietz 7y ago
yborg 7y ago
Nuclear designs are like quarterbacks, the best one is always the one "in development". The problems with all of these next-generation designs are not going to be with the physics, but the engineering. These reactors will be operating for 40+ years, and are complex collections of machinery that have wear-out and failure mechanisms that may not be discovered until years after full operation commences - when this machinery is now highly radioactive. Remember the pebble-bed reactor? Sound idea in principle, the Germans found out that its main problem was inherent in the engineering of the fuel - it turned out to produce large amounts of radioactive dust in the reactor. The description of this reactor, which involves robotic fuel handling equipment operating within the containment constantly moving around fuel elements immersed in molten sodium metal seems doomed to create difficult repair problems as these mechanisms will fail and now need to be replaced/repaired within the hot zone of the reactor. It's quite easy to build a system which technically works, but ends up being uneconomic. To my knowledge there has yet to be a successful long-term operating power generation design of any kind using sodium coolant; the Monju plant in Japan was a failure largely because of problems with the coolant loop (including a leak and serious fire). Until these basic engineering issues are proven to be solved, the fuel physics seem kind of beside the point.
- ttul 7y ago
  Excellent points. In this case, we have Bill Gates providing essentially unlimited capital to work out the problems - even if that does take decades.
- api 7y ago
  Elon would say that nuclear power has a "high PITA factor." PITA factor is "Pain in the Ass" factor and refers to technologies that look great on paper but explode into a fractal of non-obvious design and operational difficulties when put into practice. He used the term to refer to hydrogen as rocket fuel for example.

76 points by jonbaer 7y ago

After watching the Bill Gates Netflix documentary I was wondering what HN would think of the nuclear safety debate in regards to TerraPower's traveling wave design.

cagenut 7y ago
I am very wishful but its still stuck in the wishful thinking phase. Obviously the 'trade war' derailing it is a travesty, but I think its important at this point (post SR15) to recognize that wishful thinking for future tech is a form of soft/self-delusional climate change denialism. The graphs are very stark at this point. We need to turn the corner on emissions in 2020/2021. That means anything still in the R&D phase is not going to be part of the first decade of the solution. This is basic project management not even an opinion on nuclear safety/proliferation.
- DennisP 7y ago
  Yes, but if you believe that going from our current level of wind/solar to 80% wind/solar is a lot easier per gigawatt than going from 80% to 100%, then it still makes sense to develop advanced nuclear for the last part, while still rolling out wind/solar as fast as possible right now. Not to mention, fast reactors like the TWR can destroy the nuclear waste that people claim to be so worried about.
  - bassman9000 7y ago
    And they are not the only kind of reactors than can. Fast breeders can too, as well as MSR, while producing usable isotopes (e.g. medical). Waste is a solvable problem.
  - baq 7y ago
    Solar has a really bad eroi problem and I say it as an enthusiast and an owner of a microinstallation on my roof. New nuclear is absolutely necessary but it just can’t come online for a million reasons.
    - the8472 7y ago
      Some countries manage better than others. Perhaps they'll profit from electricity or hydrogen exports in the future. https://pris.iaea.org/PRIS/WorldStatistics/UnderConstructionReactorsByCountry.aspx https://pris.iaea.org/PRIS/WorldStatistics/UnderConstruction...
    - choeger 7y ago
      Eroi is a red herring. The question should be energy returned on manual labor.
      - TeMPOraL 7y ago
        How is EROI a red herring? Energy returned on manual labor may be interesting wrt. profitability, but EROI is literally whether there's any sense of doing it in the first place.
        choeger 7y ago
        The thing is: if you can output (through highly automated processes) a device that yields even just 1% more energy than it required in production over its lifetime, you have the opportunity for an exponential growth in energy production at your hands. Higher EROI might indicate a steeper growth, but you can achieve the same by just scaling up production.
    - pfdietz 7y ago
      EROI of solar is just fine. The notion that it's not is based on well-debunked flawed studies.
    - ZeroGravitas 7y ago
      Solar has a good, and continually rising, eroi. But eroi isn't really a particularly useful metric: http://bountifulenergy.blogspot.com/2018/10/reports-of-low-eroi-for-solar-power-are.html?m=1 http://bountifulenergy.blogspot.com/2018/10/reports-of-low-e...
james_s_tayler 7y ago
My theory is the documentary was actually a 3 hour commercial for the Traveling Wave Reactor.

chkaloon 7y ago

Looking at TerraPower's website, they're talking about a prototype by the mid-2020s, and they've already been working for 11 years. Would be nice to see this sped up. The Manhattan Project lasted only 4 years. We spend much more time on the ethical, safety, and proliferation considerations than we did back then, of course, and with good reason. But I wonder if this project could use a little Elon Musk hell-or-high-water drive to move it along. I'll probably get down-voted for that, but seems like a discussion worth having.

DennisP 7y ago
In the early days of nuclear power we got things done a lot faster. Now in the U.S. the government makes things unnecessarily difficult; the NRC requires a couple hundred million dollars worth of design work before they'll even take a look at a new reactor. Then they give a flat yes or no, and if it's no then you're out of business. You're pretty much forced to do a big design up front; you can't do a series of experiments and adjust as you go. Things are different in Canada, and that's why reactor startups like Terrestrial Energy are making good progress there. But the U.S. DOE has a lot of infrastructure that could really help.
mikeyouse 7y ago
The Manhattan Project also cost something like $40 billion in today's dollars and had the benefit of conscripting some of the most brilliant minds in the world (including many Europeans who fled the war) to work on it for modest salaries.
- sib 7y ago
  It sounds like a lot to me, but it's worth noting that there are individuals with more money than that (and certainly plenty of tech companies who could invest that much). The Gates Foundation alone could fund that investment.
Reedx 7y ago
It's shocking to me that the best solution we have for climate change gets downvoted on a site that's generally pro-science. But it seems to happen with every discussion about nuclear energy. Also surprising how even Bill Gates gets ignored on this issue. He's talked repeatedly about why nuclear[1][2][3], yet doesn't get a lot of traction. 1. https://www.gatesnotes.com/About-Bill-Gates/Year-in-Review-2018 https://www.gatesnotes.com/About-Bill-Gates/Year-in-Review-2... 2. https://youtu.be/d1EB1zsxW0k?t=520 https://youtu.be/d1EB1zsxW0k?t=520 3. https://ourworldindata.org/what-is-the-safest-form-of-energy https://ourworldindata.org/what-is-the-safest-form-of-energy

baybal2 7y ago

An alternative: mix californium and natural uranium and you get a solid state subcritical reactor with no need for regulation. Though, there will be no way to turn it off until Cf burns out.

rbanffy 7y ago
I am sure the use of Californium will also generate some extreme NIMBY.
pfdietz 7y ago
This is a completely terrible idea. Let's suppose we have a just barely subcritical reactor with k = .99. Then, you're going to need about 1% Cf in the core to sustain a chain reaction. The core of a 1 GW reactor contains about 100 tonnes of fuel, and fissions maybe a tonne of fuel per GW(e)-year. So, at k = .99, it would consume 10 kg of Cf per year. At current market prices this would cost $270 B/year, assuming even that much Cf were available. It would be BY FAR cheaper to provide the neutrons to drive a subcritical reactor by means of an accelerator, rather than with californium. 1 GeV protons on a uranium target will produce about 60 neutrons per proton, from spallation and fast fission. This sort of scheme has been repeatedly investigated, but has no sufficient advantage over conventional reactors to justify the extra cost and complexity.
- baybal2 7y ago
  Hmm, I think you have a miscalculation about neutronics here, and fission/capture ratios. Cf neutrons are in their majority come nicely in 1MeV-2MeV, so you have much more fission going per neutron, and much less thermal neutron captures. If you have an intense neutron emitter dispersed in fuel + moderation + reflectors you should be able to go with much lower k to generate a meaningful amount of power. You should me able to go down to single grams of Cf per megawatt. Yes, not that economical, but at least possible for things like reactors for space use and such. At that price, that will be cheaper than current RTG material. Correct me if I am wrong.
  - pfdietz 7y ago

yborg 7y ago

Nuclear designs are like quarterbacks, the best one is always the one "in development". The problems with all of these next-generation designs are not going to be with the physics, but the engineering. These reactors will be operating for 40+ years, and are complex collections of machinery that have wear-out and failure mechanisms that may not be discovered until years after full operation commences - when this machinery is now highly radioactive. Remember the pebble-bed reactor? Sound idea in principle, the Germans found out that its main problem was inherent in the engineering of the fuel - it turned out to produce large amounts of radioactive dust in the reactor. The description of this reactor, which involves robotic fuel handling equipment operating within the containment constantly moving around fuel elements immersed in molten sodium metal seems doomed to create difficult repair problems as these mechanisms will fail and now need to be replaced/repaired within the hot zone of the reactor. It's quite easy to build a system which technically works, but ends up being uneconomic. To my knowledge there has yet to be a successful long-term operating power generation design of any kind using sodium coolant; the Monju plant in Japan was a failure largely because of problems with the coolant loop (including a leak and serious fire). Until these basic engineering issues are proven to be solved, the fuel physics seem kind of beside the point.

ttul 7y ago
Excellent points. In this case, we have Bill Gates providing essentially unlimited capital to work out the problems - even if that does take decades.
api 7y ago
Elon would say that nuclear power has a "high PITA factor." PITA factor is "Pain in the Ass" factor and refers to technologies that look great on paper but explode into a fractal of non-obvious design and operational difficulties when put into practice. He used the term to refer to hydrogen as rocket fuel for example.