[HN Gopher] Book Review: The Future of Fusion Energy
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Book Review: The Future of Fusion Energy
Author : bschne
Score : 36 points
Date : 2022-01-03 20:03 UTC (2 hours ago)
(HTM) web link (martin.kleppmann.com)
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| spekcular wrote:
| What is the practical advantage of fusion power over newer
| fission reactor designs? If we desire nuclear energy, why not
| just build out, say, a bunch of molten salt reactors?
|
| It seems that the primary reasons we don't see more nuclear power
| are 1) it's highly capital intensive (big upfront investment for
| uncertain reward), and 2) it's expensive to comply with safety
| regulations. How does fusion solve these problems?
| ncmncm wrote:
| There is no practical advantage of fusion power over anything,
| because it has no practicality of any kind.
|
| We don't see more fission power because whenever a new fission
| project is started, the majority of the money is siphoned off
| for political patronage. Construction stretches out over a
| decade, because once it is finished, the money stops flowing;
| nobody actually involved wants that ever to happen. If it must
| happen, it is somewhat better to have a working power plant at
| the end, but with enough money involved, that is dispensable,
| as we see in South Carolina.
|
| This contrasts with solar and wind projects. They can start
| producing almost immediately. It is easy to multiply the cost
| of a unit of generating capacity (panel, wind turbine) times
| the number of units, and see what it should cost. There is just
| too little scope for corruption. (That might be solved, in
| time.) So, costs keep going down, year over year, driven by
| healthy competition.
| deeviant wrote:
| > We don't see more fission power because whenever a new
| fission project is started, the majority of the money is
| siphoned off for political patronage.
|
| However bad an over budget nuclear plant is, an under budget
| one would be worse.
| ChrisMarshallNY wrote:
| Much, _much_ less long-term radioactive waste.
|
| It's a lot more energy, for less fuel, but that may be
| mitigated by the cost of the reactor.
| pfdietz wrote:
| There really isn't an overall practical advantage, at least for
| DT fusion, and this has been known for decades.
|
| http://orcutt.net/weblog/wp-content/uploads/2015/08/The-Trou...
| Symmetry wrote:
| > Fusion will almost certainly have a lower power density
| than fission and therefore will require a larger plant to
| produce the same output. Suppose a fusion plant had to be ten
| times as big and therefore likely ten times as costly -- as a
| present-day fission plant to produce the same amount of
| power.
|
| I don't see how that follows. Different forms of power
| generation have orders of magnitude differences in costs on a
| per volume basis. If you're comparing within a type it might
| make sense, a coal plant 10 times larger probably does cost
| between 5 and 20 times more. But I don't see any reason to
| expect a fusion plant to have comparable per volume costs to
| a light water fission plant. And why is he assuming the cost
| is per volume rather than per mass?
| Symmetry wrote:
| 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 wrote:
| > 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 wrote:
| Only 10? Do you have a source for that? I seriously thought
| it's more like 20.
| cogman10 wrote:
| You 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/
| ncmncm wrote:
| The problem is that even if they were to get it working, it would
| still be several times as expensive to operate as the equivalent
| fission plant, which is not now competitive, and gets less so
| each year. So, at this stage there is no expectation of practical
| energy output, and thus only academic interest.
| 2OEH8eoCRo0 wrote:
| Why? Fission is expensive partly because of the safety
| requirements- and for good reason. Fusion is far safer.
| cogman10 wrote:
| Fission is expensive because of the ungodly amount of red
| tape that needs to be cut before groudbreaking can happen.
|
| Fusion will face much the same amount of red tape without
| changes to the law. Doesn't matter that it is safer, it's
| "nuclear" which is what most laws target.
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