4 ms·

>So any research results about hydrogen-boron fusion are far more important than the results about easier fusion reactions. That's like saying research results

>So any research results about hydrogen-boron fusion are far more important than the results about easier fusion reactions. That's like saying research results in exhaust filters was much more important than research into combustion engines back when we had none - how does that make any sense ? Disposing radioactive waste isn't impossible, it's just not trivial, if that was the only downside of fission plants I doubt many people would have a problem with them. Pollution produced by coal plants is categorically worse and yet we have those all over the place.

adrian_b 5y ago
It is not just the problem of disposing the waste. Any neutron shield will be destroyed in a relatively short time, so it will have to be replaced and processed for the separation of the radioactive waste. This is certain to greatly increase the cost of operation for a fusion reactor. Also the fusion energy carried by the neutrons will be recovered only partially, because it will be transformed in heat in the shield and taken away by a coolant and then the heat will be used in electric generators, like the heat produced by fission or by fossil fuel burning. Because the products of an aneutronic fusion reaction are high-speed charged particles, it is theoretically possible to make a direct electric generator, without using heat as an intermediate, which could have a much higher efficiency. Making a small fusion reactor that produces neutrons would be always impossible if living beings are close, due to the need for a neutron shield. So you will never have e.g. a car with such a fusion reactor. There are no known size limits for a fusion reactor with hydrogen-boron, so it might be possible to make reactors small enough to power a house or a vehicle. So if it would be possible to control a fusion reaction like hydrogen-boron, it would be possible to make fusion reactors that could produce much cheaper energy than it is possible with the easier fusion reactions, for which it remains to be proven if they could become economically viable, even long after the technical problems needed to enable the production of more energy than consumed will be solved. However, many real breaktroughs would be needed to discover how to do aneutronic fusion reactions, at the scale needed for energy production. The easier fusion reactions, like deuterium-tritium or deuterium-deuterium, have so many intrinsic disadvantages and so little advantages over fission reactors that it does not seem likely that they could ever become the main method for energy production.
- Retric 5y ago
  Billion degree partials produce very high energy photons. Thus it’s still producing ionizing radiation so scaling down to a car sized reactor isn’t going to practical. Further, Hydrogen born is also only aneutronic if the chamber is kept free from everything else to an impractical standard. So, yes in theory you don’t need neutron shielding, but in practice you very much need shielding at useful sustained power outputs. In the end you will still produce radioactive waste, just less of it.
  - adrian_b 5y ago
    There are negligible chances that a fusion reaction like hydrogen-boron will ever be achieved by thermal means. If such fusion reactions will ever be used, some means to accelerate the nuclei will have to be used, so that they will have a directed movement not a random thermal movement. So there will be no billion degree plasma in thermal equilibrium, radiating gamma-ray photons. Some high-energy photons will be produced in secondary reactions, but that cannot be compared to standard fusion, where producing neutrons is the intended result of the reactions. It cannot be predicted yet how much shielding might be needed, but in any case that would not be comparable with the needs of standard fusion. The real problem of the hydrogen-boron fusion is that, for now, there is no known method that could ensure a high-enough probability of collisions between accelerated nuclei and a solid target or other accelerated nuclei, so that the rate of collisions would be high enough to generate more energy than consumed.
    - Retric 5y ago
      > It cannot be predicted yet how much shielding might be needed It’s not magic, you can set useful lower bounds knowing an actual reactor would be worse.
    - DennisP 5y ago
      HB11 Energy's method is non-thermal. They use a petawatt picosecond laser, which is so intense that it shoves the target nuclei sideways into the nuclei behind them.
southerntofu 5y ago
> Disposing radioactive waste isn't impossible, it's just not trivial Source? To my knowledge, all radioactive waste disposal systems we have tried to this day have profoundly failed... and some even have failed years before they were scheduled to store any nuclear waste (eg. deadly gallery collapse in Bure, France).
- delecti 5y ago
  Most radioactive waste disposal schemes I've heard of have been shelved because of NIMBYism. But it hasn't even been an issue, because most radioactive waste is so benign that just leaving it in storage containers on-site is fine anyway.
- u320 5y ago
  There are today 0 long term waste facilities in the world, so none have failed obviously. There are a lot of (non-military) medium term waste facilities (since that is all we need right now) and none of them have experienced any radiation leak.

adrian_b 5y ago

It is not just the problem of disposing the waste. Any neutron shield will be destroyed in a relatively short time, so it will have to be replaced and processed for the separation of the radioactive waste. This is certain to greatly increase the cost of operation for a fusion reactor. Also the fusion energy carried by the neutrons will be recovered only partially, because it will be transformed in heat in the shield and taken away by a coolant and then the heat will be used in electric generators, like the heat produced by fission or by fossil fuel burning. Because the products of an aneutronic fusion reaction are high-speed charged particles, it is theoretically possible to make a direct electric generator, without using heat as an intermediate, which could have a much higher efficiency. Making a small fusion reactor that produces neutrons would be always impossible if living beings are close, due to the need for a neutron shield. So you will never have e.g. a car with such a fusion reactor. There are no known size limits for a fusion reactor with hydrogen-boron, so it might be possible to make reactors small enough to power a house or a vehicle. So if it would be possible to control a fusion reaction like hydrogen-boron, it would be possible to make fusion reactors that could produce much cheaper energy than it is possible with the easier fusion reactions, for which it remains to be proven if they could become economically viable, even long after the technical problems needed to enable the production of more energy than consumed will be solved. However, many real breaktroughs would be needed to discover how to do aneutronic fusion reactions, at the scale needed for energy production. The easier fusion reactions, like deuterium-tritium or deuterium-deuterium, have so many intrinsic disadvantages and so little advantages over fission reactors that it does not seem likely that they could ever become the main method for energy production.

Retric 5y ago
Billion degree partials produce very high energy photons. Thus it’s still producing ionizing radiation so scaling down to a car sized reactor isn’t going to practical. Further, Hydrogen born is also only aneutronic if the chamber is kept free from everything else to an impractical standard. So, yes in theory you don’t need neutron shielding, but in practice you very much need shielding at useful sustained power outputs. In the end you will still produce radioactive waste, just less of it.
- adrian_b 5y ago
  There are negligible chances that a fusion reaction like hydrogen-boron will ever be achieved by thermal means. If such fusion reactions will ever be used, some means to accelerate the nuclei will have to be used, so that they will have a directed movement not a random thermal movement. So there will be no billion degree plasma in thermal equilibrium, radiating gamma-ray photons. Some high-energy photons will be produced in secondary reactions, but that cannot be compared to standard fusion, where producing neutrons is the intended result of the reactions. It cannot be predicted yet how much shielding might be needed, but in any case that would not be comparable with the needs of standard fusion. The real problem of the hydrogen-boron fusion is that, for now, there is no known method that could ensure a high-enough probability of collisions between accelerated nuclei and a solid target or other accelerated nuclei, so that the rate of collisions would be high enough to generate more energy than consumed.
  - Retric 5y ago
    > It cannot be predicted yet how much shielding might be needed It’s not magic, you can set useful lower bounds knowing an actual reactor would be worse.
  - DennisP 5y ago
    HB11 Energy's method is non-thermal. They use a petawatt picosecond laser, which is so intense that it shoves the target nuclei sideways into the nuclei behind them.

southerntofu 5y ago

> Disposing radioactive waste isn't impossible, it's just not trivial Source? To my knowledge, all radioactive waste disposal systems we have tried to this day have profoundly failed... and some even have failed years before they were scheduled to store any nuclear waste (eg. deadly gallery collapse in Bure, France).

delecti 5y ago
Most radioactive waste disposal schemes I've heard of have been shelved because of NIMBYism. But it hasn't even been an issue, because most radioactive waste is so benign that just leaving it in storage containers on-site is fine anyway.
u320 5y ago
There are today 0 long term waste facilities in the world, so none have failed obviously. There are a lot of (non-military) medium term waste facilities (since that is all we need right now) and none of them have experienced any radiation leak.