2 ms·

From googling around, most rock melts at around 1000C, so I guess the biggest challenge is making a reactor that will survive heating up to 1000C? The melting p

From googling around, most rock melts at around 1000C, so I guess the biggest challenge is making a reactor that will survive heating up to 1000C? The melting point of uranium is barely 1100C, so seems like an awful thin margin. How would they handle not irradiating (and generating all sorts of isotopes in) the tunnel walls? A 10MW reactor generates a fuckton of radiation. Nobody could come anywhere near the "melting" head, even after shutdown. Wouldn't hitting even a tiny amount of water would be catastrophically bad, causing a steam explosion? Hitting oil deposits, coal...minerals that contain water...

R0b0t1 5y ago
The reactor doesn't need to touch the rock
- ganzuul 5y ago
  I needs coolant though.
acidburnNSA 5y ago
The melting point of uranium metal may be around there, but these reactors would use a much higher temperature fuel form, such as the everyday uranium oxide (UO₂) used in nearly all commercial reactors, which melts around 2900°C. Usually it's the coolant and structural materials that limit temperature in nuclear reactors. These could use exotic materials like SiC for structure. Interesting that they use liquid metal heat pipes in this study to transfer the heat to the rock melting surfaces.
GenerocUsername 5y ago
Not a Nuclear Mechanical Engineer, but I bet you could concentrate the heat of the reactors using a giant nuclear-grade heat pump to concentrate heat well above the point-temperature of the reactor itself. As long as the fuel is generating X Watts of power, you can theoretically concentrate that energy away and down to smaller and smaller areas, increasing temperature as you go.
- davidmanheim 5y ago
  We should probably ask someone who took a heat transfer or other undergrad physics class, but from my basic understanding of the physics, "concentrating heat" isn't really a thing - at the very least, you'd need to extract the energy from a heat differential into some other form to do this.

R0b0t1 5y ago

The reactor doesn't need to touch the rock

ganzuul 5y ago
I needs coolant though.

acidburnNSA 5y ago

The melting point of uranium metal may be around there, but these reactors would use a much higher temperature fuel form, such as the everyday uranium oxide (UO₂) used in nearly all commercial reactors, which melts around 2900°C. Usually it's the coolant and structural materials that limit temperature in nuclear reactors. These could use exotic materials like SiC for structure. Interesting that they use liquid metal heat pipes in this study to transfer the heat to the rock melting surfaces.

GenerocUsername 5y ago

Not a Nuclear Mechanical Engineer, but I bet you could concentrate the heat of the reactors using a giant nuclear-grade heat pump to concentrate heat well above the point-temperature of the reactor itself. As long as the fuel is generating X Watts of power, you can theoretically concentrate that energy away and down to smaller and smaller areas, increasing temperature as you go.

davidmanheim 5y ago
We should probably ask someone who took a heat transfer or other undergrad physics class, but from my basic understanding of the physics, "concentrating heat" isn't really a thing - at the very least, you'd need to extract the energy from a heat differential into some other form to do this.