3 ms·

I've always thought if the reactor was so small then why can't we just by default build the reactors underground? Isn't the underground a more stable area to be

I've always thought if the reactor was so small then why can't we just by default build the reactors underground? Isn't the underground a more stable area to begin with? Even during earthquakes? Reactor waste could be stored at the location permanently and if the reactor gets the 1 in a million accident then the whole place is already basically built in a cement/rock containment vessel. If a serious meltdown occurs then it would be easy to just start pouring lead or cement into the facility. Even if there was a small nuclear explosion we already know the impacts of underground nuclear explosions.

jabl 8y ago
Many of the current small reactor concepts are indeed designed to be installed below grade.
JumpCrisscross 8y ago
> why can't we just by default build the reactors underground? It would appear to carry an increased risk of hidden problems and groundwater poisoning. There might also be issues with corrosion and accessibility for maintenance. That said, I'm not ruling it out. A lesson these new approaches to nuclear engineering is that we never figured out the right defaults the last time around. We were too focussed on making bombs and submarines. > we already know the impacts of underground nuclear explosions Nuclear plants should never fail by way of nuclear explosion. If this is a possibility it is a bad reactor design.
- pfdietz 8y ago
  > Nuclear plants should never fail by way of nuclear explosion. If this is a possibility it is a bad reactor design. Fast reactors have always had this potential problem, since they require a much higher density of high enrichment material. A larger fast reactor might have a ton of plutonium in it; in an accident where fuel is melting and moving around unpredictably it's hard to prove that a prompt supercritical mass of Pu won't assemble somewhere. Edward Teller famously warned about this in 1967. This is one advantage of MSRs as fast reactors: the fuel is already dispersed in salt, so such rearrangement is less plausible.
  - donttrustatoms 8y ago
    "Fast reactors have always had this potential problem" - Not really. Check out the dramatic experiments at EBR-II (fast reactor) demonstrating unprotected loss of coolant at full power. It shut itself down. Without damage. And started back up later that day, and operated that year, as a research reactor, with better uptime (capacity factor) than the fleet at the time.
    - pfdietz 8y ago
      That just shows that in that particular accident scenario the situation would not arise.

jabl 8y ago

Many of the current small reactor concepts are indeed designed to be installed below grade.

JumpCrisscross 8y ago

> why can't we just by default build the reactors underground? It would appear to carry an increased risk of hidden problems and groundwater poisoning. There might also be issues with corrosion and accessibility for maintenance. That said, I'm not ruling it out. A lesson these new approaches to nuclear engineering is that we never figured out the right defaults the last time around. We were too focussed on making bombs and submarines. > we already know the impacts of underground nuclear explosions Nuclear plants should never fail by way of nuclear explosion. If this is a possibility it is a bad reactor design.

pfdietz 8y ago
> Nuclear plants should never fail by way of nuclear explosion. If this is a possibility it is a bad reactor design. Fast reactors have always had this potential problem, since they require a much higher density of high enrichment material. A larger fast reactor might have a ton of plutonium in it; in an accident where fuel is melting and moving around unpredictably it's hard to prove that a prompt supercritical mass of Pu won't assemble somewhere. Edward Teller famously warned about this in 1967. This is one advantage of MSRs as fast reactors: the fuel is already dispersed in salt, so such rearrangement is less plausible.
- donttrustatoms 8y ago
  "Fast reactors have always had this potential problem" - Not really. Check out the dramatic experiments at EBR-II (fast reactor) demonstrating unprotected loss of coolant at full power. It shut itself down. Without damage. And started back up later that day, and operated that year, as a research reactor, with better uptime (capacity factor) than the fleet at the time.
  - pfdietz 8y ago
    That just shows that in that particular accident scenario the situation would not arise.