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Safety is a lot easier to achieve with fusion because it stops producing power instantly when containment fails and the amount of energy in the plasma isn't tha
by Symmetry 5y ago
Safety is a lot easier to achieve with fusion because it stops producing power instantly when containment fails and the amount of energy in the plasma isn't that high. It's hard to make a fission reactor both large enough for commercial scale and safe without cooling.
The second benefit is not producing high level radioactive waste. With fission you can't really get away from the decay products of your fissile materials, they're intrinsic to the process. With DT fusion you get He4 which is stable and neutrons. The neutrons are dangerous but will either quickly decay or be absorbed by something. By controlling what gets exposed to the neutron flux you can in principle achieve arbitrarily low levels of radioactive waste. That's a serious engineering challenge to get as low as possible but my understanding is that it's not hard to produce much less than with fission. You also want to produce Tritium which will later get consumed in the fusion process leaving only a moderate amount stored at any time so if things go well its not a long term problem. If the storage ruptures in a gentle then it escapes high up into the atmosphere. In the event of a containment breach you're probably going to get super heavy water steam which is an issue.
The regulatory framework is a real concern, depending on how many rules carry over from fission reactors. Back in the 1970s the term "fallout" carried connotations of people dying painfully in hours after exposure which is a different association than people born after the Cold War have. Also electricity generation back then was done on a cost plus basis so the people running the fission plants had every incentive that their costs were increased as much as possible. That isn't how we run our electricity grids any more so there aren't strong forces on the industry side fighting for tighter regulations.
- cogman10 5y ago> It's hard to make a fission reactor both large enough for commercial scale and safe without cooling. Gen IV reactors all fit that bill. They all have passive safety properties (so, cut the power and the plant shuts down, no nuclear meltdowns) and they have very large outputs (2GW in the largest plants). > The second benefit is not producing high level radioactive waste. With fission you can't really get away from the decay products of your fissile materials, they're intrinsic to the process. Again, Gen IV reactors are much better than previous reactors in this aspect. While they do produce radio active waste, it's generally far more used (producing less waste) and radioactive for a far shorter time (hundreds of years vs 1000s). > The regulatory framework is a real concern, depending on how many rules carry over from fission reactors. This is the big sticking point that hurts the bottom line of fission reactors and will hurt fusion reactors. Without changes to the laws, nuclear power plants are going to have a rough time turning a profit. They mostly aren't unprofitable because of construction cost, but rather regulatory overhead. It takes over 10 years to construct and turn on new reactors in the US, which is a major problem.
- baq 5y agoOnly 10? Do you have a source for that? I seriously thought it’s more like 20.
- cogman10 5y agoYou are probably right. I'm relying on my fuzzy memory for that number (I've looked it up in the past). This article [1] says 5 years to license, 5->7 years to build, and then the verification time with the electric company before it can be switched on. [1] http://large.stanford.edu/courses/2017/ph241/park-k2/ http://large.stanford.edu/courses/2017/ph241/park-k2/