7 ms·

Could you elaborate on the economics? My internal model has always been "1 Joule -> Water -> Hydrogen -> Fusion Reactor -> (1 + epsilon) Joules" was a money pri

by nmca 7y ago

Could you elaborate on the economics? My internal model has always been "1 Joule -> Water -> Hydrogen -> Fusion Reactor -> (1 + epsilon) Joules" was a money printing machine for obvious reasons, but I can see that there are lots of hidden assumptions there.

pfdietz 7y ago
Fusion reactors will be much larger and more expensive than fission reactors. Yes, the fuel is potentially cheaper, but fuel is only a minor part of the cost of power from a fission reactor. The cost of the power plant and non fuel operating costs (like, replacing substantial radioactive components of a fusion reactor every few years due to neutron damage) will be much more important. The usual mistake people make in thinking about fusion is to focus on fuel cost and assume, incorrectly, that fuel cost determines the cost of power. The equipment has to be financed and paid for and maintained, and the cost of doing that will dominate.
- nmca 7y ago
  This sort of thing? https://ieeexplore.ieee.org/document/4323282 https://ieeexplore.ieee.org/document/4323282 My physics is fairly limited, but I'm not familiar of many cases where induced radioactivity has ever been a concern, or neutron bombardment has caused physical damage? Hoping for pointers :)
  - pfdietz 7y ago
    Vaguely, but at much higher radiation doses. Every atom in the first wall of a DT fusion reactor will be knocked out of position by a neutron about once every three days, on average. The material properties will progressively degrade. Metals will swell and become brittle. Some of the atoms will be transmuted, producing new radioactive ones and sometimes hydrogen or helium atoms that will diffuse into defects, forming high pressure gas bubbles. Even in so-called "advanced fuel" reactors, burning a mixture other than DT, there will be enough neutrons to render the reactor structure too radioactive for hands-on maintenance. This will greatly complicate the problem of fixing the reactor if it breaks.
- sandworm101 7y ago
  Much (most?) of the costs associated with current fusion reactors stems from the fact they are essentially large science experiments. They have wider operational parameters. They are riddled with sensors. Commercial reactors will be built for very specific narrow operating regimes. They will not need all the sensors. They will not be science experiments. They will be far far cheaper than current reactors.
  - opportune 7y ago
    Producing the parts would also become commoditized. A major cost factor in lots of high tech research (see also: spacecraft) is that the parts are made individually, so they need to be designed/engineered/tested roughly individually and built from essentially scratch.
  - pfdietz 7y ago
    If ITER had a turbine and generator attached, and ignoring that it doesn't have a breeding blanket, it would cost about $100/W. This is an order of magnitude higher than fission power plants, and a factor of 30 more than PV (adjusted for capacity factor).

by nmca 7y ago

pfdietz 7y ago

Fusion reactors will be much larger and more expensive than fission reactors. Yes, the fuel is potentially cheaper, but fuel is only a minor part of the cost of power from a fission reactor. The cost of the power plant and non fuel operating costs (like, replacing substantial radioactive components of a fusion reactor every few years due to neutron damage) will be much more important. The usual mistake people make in thinking about fusion is to focus on fuel cost and assume, incorrectly, that fuel cost determines the cost of power. The equipment has to be financed and paid for and maintained, and the cost of doing that will dominate.

nmca 7y ago
This sort of thing? https://ieeexplore.ieee.org/document/4323282 https://ieeexplore.ieee.org/document/4323282 My physics is fairly limited, but I'm not familiar of many cases where induced radioactivity has ever been a concern, or neutron bombardment has caused physical damage? Hoping for pointers :)
- pfdietz 7y ago
  Vaguely, but at much higher radiation doses. Every atom in the first wall of a DT fusion reactor will be knocked out of position by a neutron about once every three days, on average. The material properties will progressively degrade. Metals will swell and become brittle. Some of the atoms will be transmuted, producing new radioactive ones and sometimes hydrogen or helium atoms that will diffuse into defects, forming high pressure gas bubbles. Even in so-called "advanced fuel" reactors, burning a mixture other than DT, there will be enough neutrons to render the reactor structure too radioactive for hands-on maintenance. This will greatly complicate the problem of fixing the reactor if it breaks.
sandworm101 7y ago
Much (most?) of the costs associated with current fusion reactors stems from the fact they are essentially large science experiments. They have wider operational parameters. They are riddled with sensors. Commercial reactors will be built for very specific narrow operating regimes. They will not need all the sensors. They will not be science experiments. They will be far far cheaper than current reactors.
- opportune 7y ago
  Producing the parts would also become commoditized. A major cost factor in lots of high tech research (see also: spacecraft) is that the parts are made individually, so they need to be designed/engineered/tested roughly individually and built from essentially scratch.
- pfdietz 7y ago
  If ITER had a turbine and generator attached, and ignoring that it doesn't have a breeding blanket, it would cost about $100/W. This is an order of magnitude higher than fission power plants, and a factor of 30 more than PV (adjusted for capacity factor).