3 ms·

> Conventional nukes aren't great at going to these temperatures so this is mostly a thing "advanced" reactor people talk about. Are the temperatures too high

> Conventional nukes aren't great at going to these temperatures so this is mostly a thing "advanced" reactor people talk about. Are the temperatures too high or too low?

Analemma_ 7y ago
Too low - water-cooled reactors are designed to bring the water in the secondary cooling system to just above the boiling point, because anything beyond that is wasted energy (the temperature of the steam doesn't really matter as far as driving turbines). So retrofitting a molten-salt system onto these reactors isn't very efficient and you would ideally want a new reactor design intended for that from the beginning.
- jandrese 7y ago
  It seems like a serious materials challenge problem to come up with a molten salt that has the right nuclear characteristics (neutron moderating, etc...) and is not horribly corrosive/flammable/etc... Especially if your usage model is to let the salts heat up to outrageously high temperatures during the day and then draw them down over night.
- SECProto 7y ago
  > (the temperature of the steam doesn't really matter as far as driving turbines) This goes against everything I seem to remember from thermodynamics - superheated steam is exactly what is used for driving turbines, with saturated steam as the cold side outlet of the turbine. It's what makes district heating useful - there is still heat energy left in the saturated steam, too low grade for driving turbines, but still useful for heating apartments etc
  - stickfigure 7y ago
    Indeed, superheaters have been used since the early 1900s to dramatically increase the thermal efficiency of steam engines. https://en.wikipedia.org/wiki/Superheater https://en.wikipedia.org/wiki/Superheater Also, IIRC superheaters are especially important in turbine applications because water droplets damage the blades.
  - mcguire 7y ago
    What's your turbine pressure? Steam at 700°F is apparently 3000psi, which is the highest temperature/pressure I can find. Edit: Best Q/A thread I've seen recently: https://www.researchgate.net/post/At_what_temperature_water_will_decompose_to_Oxygen_and_Hydrogen https://www.researchgate.net/post/At_what_temperature_water_... "We need this value to be more specific numerical form to utilize in design of high temperature and high pressure steam boilers and turbines working at 300 bars."
    - deleted 7y ago
      [deleted]

> Conventional nukes aren't great at going to these temperatures so this is mostly a thing "advanced" reactor people talk about. Are the temperatures too high or too low?

Analemma_ 7y ago

Too low - water-cooled reactors are designed to bring the water in the secondary cooling system to just above the boiling point, because anything beyond that is wasted energy (the temperature of the steam doesn't really matter as far as driving turbines). So retrofitting a molten-salt system onto these reactors isn't very efficient and you would ideally want a new reactor design intended for that from the beginning.

jandrese 7y ago
It seems like a serious materials challenge problem to come up with a molten salt that has the right nuclear characteristics (neutron moderating, etc...) and is not horribly corrosive/flammable/etc... Especially if your usage model is to let the salts heat up to outrageously high temperatures during the day and then draw them down over night.
SECProto 7y ago
> (the temperature of the steam doesn't really matter as far as driving turbines) This goes against everything I seem to remember from thermodynamics - superheated steam is exactly what is used for driving turbines, with saturated steam as the cold side outlet of the turbine. It's what makes district heating useful - there is still heat energy left in the saturated steam, too low grade for driving turbines, but still useful for heating apartments etc
- stickfigure 7y ago
  Indeed, superheaters have been used since the early 1900s to dramatically increase the thermal efficiency of steam engines. https://en.wikipedia.org/wiki/Superheater https://en.wikipedia.org/wiki/Superheater Also, IIRC superheaters are especially important in turbine applications because water droplets damage the blades.
- mcguire 7y ago
  What's your turbine pressure? Steam at 700°F is apparently 3000psi, which is the highest temperature/pressure I can find. Edit: Best Q/A thread I've seen recently: https://www.researchgate.net/post/At_what_temperature_water_will_decompose_to_Oxygen_and_Hydrogen https://www.researchgate.net/post/At_what_temperature_water_... "We need this value to be more specific numerical form to utilize in design of high temperature and high pressure steam boilers and turbines working at 300 bars."
  - deleted 7y ago
    [deleted]