4 ms·

How is it "not the solution". Having 50MW of base load being able to be deployed anywhere could allow for everything else covered by renewables. If I were a po

How is it "not the solution". Having 50MW of base load being able to be deployed anywhere could allow for everything else covered by renewables. If I were a poor remote county and I wanted to make sure that 1) my residents emergency needs were covered hospital, sanitation, water, emergency heating, etc 2) also had access to cheap power Having one of these provide the base load for critical infra allows one to shop around for cheap renewable power wherever it may come from.

Manuel_D 4y ago
Nuclear reactor output scales with volume but cost scales with surface area. So a larger plant is more efficient. If the smaller reactors can take advantage of easier fabrication and logistics they might be cheaper, but that is an unknown.
- sitkack 4y ago
  Efficiency is only one dimension, these reactors can be distributed to the point of use. Efficiency should be measured in its local universe.
  - Manuel_D 4y ago
    Electricity is pretty easy to transport over 50-100 miles. One big plant servicing a whole metro is as efficient as smaller reactors distributed around. It's only when you have to transport electricity over 300+ miles where more exotic things like HVDC lines become necessary.
  - jillesvangurp 4y ago
    You are forgetting about security. One of these things and some explosives could do a lot of damage. Think dirty bombs. Each and every one will need 24x7 security for the duration of it's life. They simply can't be left unattended. Not impossible to do but it adds a lot of cost One of these things falling into the hands of extremists would be very bad. The sensible way to deploy these would be in groups close to existing infrastructure in places that can be easily secured. For example de-commissioned coal plants or nuclear plants. Security also raises the cost of operation of course. Just because it is small physically does not mean the risk is smaller. So, same level of security as with a big nuclear plant. Same level of cost. But less energy. Co-locating allows you to reduce that cost.
- pfdietz 4y ago
  How could cost scale with surface area? The mass of a nuclear power plant scales proportionally to volume. The thickness of a pressure vessel or pipe increases as you scale it up, at constant pressure.
  - deleted 4y ago
    [deleted]
  - Manuel_D 4y ago
    The pressure vessel is not a solid mass of steel, it's a hollow container. The thickness of the walls remains the same for the same pressure (it does need to increase slightly because it needs to support the weight of the pressure vessel itself) but the volume increase is cubic. Cubic volume increase vs. quadratic surface area increase means larger sizes are more effective.
    - pfdietz 4y ago
      No, that's wrong. For a pressure vessel made of the same material, the same geometry (scaled), and operating at the same safety factor, the thickness of the wall is proportional to the linear dimensions of the vessel. Here's a simple argument about why that's true: https://yarchive.net/space/launchers/fuel_tank_scaling_laws.html https://yarchive.net/space/launchers/fuel_tank_scaling_laws.... > Take any plane that slices through the pressure vessel, and consider the problem of trying to prevent the vessel from separating at that plane. The pressure load trying to cause such a separation is proportional to the surface area of the slice. The wall length available to resist it is the outer edge of the slice. The load scales with the square of size, the wall length only linearly... so as the size goes up, the wall thickness must grow as well. Chase it through the math, and wall mass is simply proportional to volume. It's also a consequence of the virial theorem of mechanics. Below a certain size you run into code minimums, but nuclear power plants will be well above that size.
      - deleted 4y ago
        [deleted]
      - 4y ago
- sitkack 4y ago
  You are talking past the point I made to only focus on raw scaling efficiency, I am talking about capabilities, both technical as well as economic. You are arguing big-o.
panick21_ 4y ago
I am not against that in general, but your never gone do that seriously with PWRs. There are designs where this does make some sense. However that is not the backbone of your infrastructure. I makes much more sense to start with one large scale design 500MW+ and deploy that as many times as you can and then you can see the places where that is overkill and you develop smaller reactors for those regions. But in most countries with ~500MW design you can reach 80-90%+ of the population and since the design would be so well known and so mass produced it might make sense to just build more of those rather then some 50MW reactor that might be only be 25% the cost but 10% the production.

Manuel_D 4y ago

Nuclear reactor output scales with volume but cost scales with surface area. So a larger plant is more efficient. If the smaller reactors can take advantage of easier fabrication and logistics they might be cheaper, but that is an unknown.

sitkack 4y ago
Efficiency is only one dimension, these reactors can be distributed to the point of use. Efficiency should be measured in its local universe.
- Manuel_D 4y ago
  Electricity is pretty easy to transport over 50-100 miles. One big plant servicing a whole metro is as efficient as smaller reactors distributed around. It's only when you have to transport electricity over 300+ miles where more exotic things like HVDC lines become necessary.
- jillesvangurp 4y ago
  You are forgetting about security. One of these things and some explosives could do a lot of damage. Think dirty bombs. Each and every one will need 24x7 security for the duration of it's life. They simply can't be left unattended. Not impossible to do but it adds a lot of cost One of these things falling into the hands of extremists would be very bad. The sensible way to deploy these would be in groups close to existing infrastructure in places that can be easily secured. For example de-commissioned coal plants or nuclear plants. Security also raises the cost of operation of course. Just because it is small physically does not mean the risk is smaller. So, same level of security as with a big nuclear plant. Same level of cost. But less energy. Co-locating allows you to reduce that cost.
pfdietz 4y ago
How could cost scale with surface area? The mass of a nuclear power plant scales proportionally to volume. The thickness of a pressure vessel or pipe increases as you scale it up, at constant pressure.
- deleted 4y ago
  [deleted]
- Manuel_D 4y ago
  The pressure vessel is not a solid mass of steel, it's a hollow container. The thickness of the walls remains the same for the same pressure (it does need to increase slightly because it needs to support the weight of the pressure vessel itself) but the volume increase is cubic. Cubic volume increase vs. quadratic surface area increase means larger sizes are more effective.
  - pfdietz 4y ago
    No, that's wrong. For a pressure vessel made of the same material, the same geometry (scaled), and operating at the same safety factor, the thickness of the wall is proportional to the linear dimensions of the vessel. Here's a simple argument about why that's true: https://yarchive.net/space/launchers/fuel_tank_scaling_laws.html https://yarchive.net/space/launchers/fuel_tank_scaling_laws.... > Take any plane that slices through the pressure vessel, and consider the problem of trying to prevent the vessel from separating at that plane. The pressure load trying to cause such a separation is proportional to the surface area of the slice. The wall length available to resist it is the outer edge of the slice. The load scales with the square of size, the wall length only linearly... so as the size goes up, the wall thickness must grow as well. Chase it through the math, and wall mass is simply proportional to volume. It's also a consequence of the virial theorem of mechanics. Below a certain size you run into code minimums, but nuclear power plants will be well above that size.
    - deleted 4y ago
      [deleted]
    - 4y ago
sitkack 4y ago
You are talking past the point I made to only focus on raw scaling efficiency, I am talking about capabilities, both technical as well as economic. You are arguing big-o.

panick21_ 4y ago

I am not against that in general, but your never gone do that seriously with PWRs. There are designs where this does make some sense. However that is not the backbone of your infrastructure. I makes much more sense to start with one large scale design 500MW+ and deploy that as many times as you can and then you can see the places where that is overkill and you develop smaller reactors for those regions. But in most countries with ~500MW design you can reach 80-90%+ of the population and since the design would be so well known and so mass produced it might make sense to just build more of those rather then some 50MW reactor that might be only be 25% the cost but 10% the production.