4 ms·

"Clean"? Less dirty than fission, absolutely. Enough less dirty to make it manageable in a way that fission doesn't seem to be, more than likely. But not cl

"Clean"? Less dirty than fission, absolutely. Enough less dirty to make it manageable in a way that fission doesn't seem to be, more than likely. But not clean. Any material in and around the reactor becomes nuclear waste in the same manner as it does for fission: by getting blasted with high-energy particles until it becomes radioactive. And while there wouldn't be any spent fuel rods to deal with, one of the products of hydrogen fusion, tritium, is also a source of concern.

DennisP 14y ago
Tritium is part of the fuel for this type of fusion reactor. Since tritium basically doesn't exist in nature (due to its twelve-year half-life), the reactor will produce it by absorbing as many neutrons as possible in a blanket of lithium.
danielweber 14y ago
The first fission plants will involve neutrons, but aneutronic fission would be the next step after that. It would require getting the fire hotter/denser. Isn't tritium a nuclear fuel?
InclinedPlane 14y ago
Clean, yes. By any measure, cleaner than what else is out there. Already a fission nuclear power plant will produce less leakage of radioactivity into the environment than many coal plants, fusion drops that level several orders of magnitude more. First off, no fission products, which are typically the most dangerous radioactive waste from fission reactors. Second, the materials used in the reactors don't have the same engineering constraints that fission reactors do and so can be chosen to produce far lower quantities of hazardous radioactive isotopes bred from intense neutron flux bombardment. Also, Tritium is a fuel, and of enormous value so it would be handled very carefully. More so, it would be bred specifically in custom built containment vessels within the reactor. On top of all that you have the fact that a fusion reactor cannot be made to undergo a meltdown or overload the way a fission reactor can. If something bad happens in a fusion reactor the immediate result is usually that fusion stops, which compares very favorably to the what happens in a fission reactor: fission chain reactions continue, temperatures build as the heat from fission products decaying builds up, etc. And you don't have weapon proliferation concerns. Overall what you have with nuclear fusion reactors is no chance of a meltdown, very much less hazardous waste generated (by orders of magnitude) and a very clean energy profile.
- jpxxx 14y ago
  ^ -intact- fission nuclear power plant ^ should ^ might ^ dramatically greater engineering constraints than fission reactors ^ (if you exclude engineering and manufacturing and plant construction costs) Sorry for the highlighter attack, but fusion still means building extraordinarily complex and expensive reactors that are going to have one hell of a carbon footprint and shed tons of radioactive waste in normal operation. Let's roll it back to "potentially cleaner in some key ways".
  - deleted 14y ago
    [deleted]
  - InclinedPlane 14y ago
    This is just plain FUD with no backing in reality. Let me make it as clear as possible. Fusion energy is fundamentally safer and cleaner than fission energy, period. Firstly, it is simply not physically possible for fusion energy to generate even a tenth as much of the radioactive waste as an equivalent fission power plant. Secondly, it is not possible to have a dangerous power excursion at a fusion plant. When a fusion plant malfunctions it doesn't experience a runaway reaction, it stops working. If a fusion plant experiences some sort of catastrophic structural failure everything stops. This is in stark contrast to fission reactors which can undergo continued fission chain-reactions even if, and perhaps especially if, the reactor vessel is disrupted and the fuel melts down and also produce fission byproduct isotopes which continue to generate enough heat after the fission reactions have stopped to melt the reactor core if it is not continuously cooled. Also, there is little evidence that the construction of a fusion reactor would entail a higher energy-usage footprint than a fission reactor, and the lack of a need for massive reinforced concrete structures in a fusion reactor tends to argue that the footprint would be rather less. Let's roll it forward back to: undoubtedly cleaner if it can be made to work.
    - jpxxx 14y ago
      I hear how passionate you are on this issue and I understand the enthusiasm. I'm not here to strangle the baby in the cradle. But my concerns are real. Granted: Fusion energy is a conceptually simpler process that is virtually impossible to runaway by its very nature. That alone is a massive plus any way you look at it. Granted: the total bulk volume of radioactive waste products is dramatically lessened. Granted: the radionuclides created by a fusion reactor are likely to be less problematic than those from a fission reactor. My points: There is still radioactive waste: magnetic confinement reactor liners will handle so much corrosive flux they'll essentially be disposable and replaced frequently - possibly on the order of weeks or months. Same (but lessened) story for inertial confinement reactor liners and the metallic waste products. Those have to go somewhere safe. They're not small. Same story for the electrical generation system. Regardless of the final reactor type, it's still going to involve managing heat-exchange fluids with neutron exposure. Then there's the environmental + carbon load from building a reactor complex, which is not going to be quantifiable until there are working reactor designs and working fuel flows and a working understanding of how much staffing and security and land and ancillary support is needed. NIMBY is going to be just as strong for fusion as it is for fission, and that's going to mean compromises. Then there's going to be the cost of purifying the fuel source, which won't be negligible when it literally involves boiling the seas. Then packaging it. Then shipping it. Then handling the waste products. Then planning for the plant's functional lifetime, which won't be forever. The conceptual clarity of fusion is wonderful and I fully support the research, but the execution is going to be quite a bit less sexy and come with some well-known downsides.

DennisP 14y ago

Tritium is part of the fuel for this type of fusion reactor. Since tritium basically doesn't exist in nature (due to its twelve-year half-life), the reactor will produce it by absorbing as many neutrons as possible in a blanket of lithium.

danielweber 14y ago

The first fission plants will involve neutrons, but aneutronic fission would be the next step after that. It would require getting the fire hotter/denser. Isn't tritium a nuclear fuel?

InclinedPlane 14y ago

Clean, yes. By any measure, cleaner than what else is out there. Already a fission nuclear power plant will produce less leakage of radioactivity into the environment than many coal plants, fusion drops that level several orders of magnitude more. First off, no fission products, which are typically the most dangerous radioactive waste from fission reactors. Second, the materials used in the reactors don't have the same engineering constraints that fission reactors do and so can be chosen to produce far lower quantities of hazardous radioactive isotopes bred from intense neutron flux bombardment. Also, Tritium is a fuel, and of enormous value so it would be handled very carefully. More so, it would be bred specifically in custom built containment vessels within the reactor. On top of all that you have the fact that a fusion reactor cannot be made to undergo a meltdown or overload the way a fission reactor can. If something bad happens in a fusion reactor the immediate result is usually that fusion stops, which compares very favorably to the what happens in a fission reactor: fission chain reactions continue, temperatures build as the heat from fission products decaying builds up, etc. And you don't have weapon proliferation concerns. Overall what you have with nuclear fusion reactors is no chance of a meltdown, very much less hazardous waste generated (by orders of magnitude) and a very clean energy profile.

jpxxx 14y ago
^ -intact- fission nuclear power plant ^ should ^ might ^ dramatically greater engineering constraints than fission reactors ^ (if you exclude engineering and manufacturing and plant construction costs) Sorry for the highlighter attack, but fusion still means building extraordinarily complex and expensive reactors that are going to have one hell of a carbon footprint and shed tons of radioactive waste in normal operation. Let's roll it back to "potentially cleaner in some key ways".
- deleted 14y ago
  [deleted]
- InclinedPlane 14y ago
  This is just plain FUD with no backing in reality. Let me make it as clear as possible. Fusion energy is fundamentally safer and cleaner than fission energy, period. Firstly, it is simply not physically possible for fusion energy to generate even a tenth as much of the radioactive waste as an equivalent fission power plant. Secondly, it is not possible to have a dangerous power excursion at a fusion plant. When a fusion plant malfunctions it doesn't experience a runaway reaction, it stops working. If a fusion plant experiences some sort of catastrophic structural failure everything stops. This is in stark contrast to fission reactors which can undergo continued fission chain-reactions even if, and perhaps especially if, the reactor vessel is disrupted and the fuel melts down and also produce fission byproduct isotopes which continue to generate enough heat after the fission reactions have stopped to melt the reactor core if it is not continuously cooled. Also, there is little evidence that the construction of a fusion reactor would entail a higher energy-usage footprint than a fission reactor, and the lack of a need for massive reinforced concrete structures in a fusion reactor tends to argue that the footprint would be rather less. Let's roll it forward back to: undoubtedly cleaner if it can be made to work.
  - jpxxx 14y ago
    I hear how passionate you are on this issue and I understand the enthusiasm. I'm not here to strangle the baby in the cradle. But my concerns are real. Granted: Fusion energy is a conceptually simpler process that is virtually impossible to runaway by its very nature. That alone is a massive plus any way you look at it. Granted: the total bulk volume of radioactive waste products is dramatically lessened. Granted: the radionuclides created by a fusion reactor are likely to be less problematic than those from a fission reactor. My points: There is still radioactive waste: magnetic confinement reactor liners will handle so much corrosive flux they'll essentially be disposable and replaced frequently - possibly on the order of weeks or months. Same (but lessened) story for inertial confinement reactor liners and the metallic waste products. Those have to go somewhere safe. They're not small. Same story for the electrical generation system. Regardless of the final reactor type, it's still going to involve managing heat-exchange fluids with neutron exposure. Then there's the environmental + carbon load from building a reactor complex, which is not going to be quantifiable until there are working reactor designs and working fuel flows and a working understanding of how much staffing and security and land and ancillary support is needed. NIMBY is going to be just as strong for fusion as it is for fission, and that's going to mean compromises. Then there's going to be the cost of purifying the fuel source, which won't be negligible when it literally involves boiling the seas. Then packaging it. Then shipping it. Then handling the waste products. Then planning for the plant's functional lifetime, which won't be forever. The conceptual clarity of fusion is wonderful and I fully support the research, but the execution is going to be quite a bit less sexy and come with some well-known downsides.