4 ms·

What kind of waste do fast reactors produce?

credit_guy 4y ago
Reactors in general produce 3 types of waste: - fission products: after a Uranium or Plutonium atom splits, the daughter atoms are virtually always radioactive; the vast majority of these atoms have a half life of less than 100 years - actinides: Uranium and Plutonium absorb a neutron but don't undergo fission. The resulting atoms, heavier than U or Pu, are part of the Actinide group, and they are quite nasty - unburned fissile material: no reactor has a 100% efficiency, a part of the U235 or Pu239 is left unburned - low and intermediate level waste: various materials inside and around the reactor, which either absorb neutrons and become "activated", i.e. radioactive, or simply get mixed up with particles of the first 3 categories. Fast reactors produce very little actinides. Maybe 1-2% of what regular reactors produce. They also burn much more of their fuel, so there's less waster of the third category. The coolant in various fast reactors is sometimes Sodium. Sodium very rarely becomes activated, and when it does, it transmutes into an element with half life of 15 days, which then decays into a stable isotope. So, after a few years, what's left is not radioactive anymore. If however, the coolant gets contaminated with particles from the nuclear fuel, then it becomes more complex. For modern reactors, the Department of Energy envisions using Triso fuel, which they consider to be virtually indestructible [1]. If that is so, then the coolant in sodium-cooled fast reactors can be considered a very law level waste. Another type of waste is the structural steel around the core subjected to the neutron bombardment coming from the core. That steel, when activated, transmutes into some isotopes that have a half-life of decades, so that's a bit nasty. That's not specific to fast reactors, it's something in common with regular reactors. [1] https://www.energy.gov/ne/articles/triso-particles-most-robust-nuclear-fuel-earth https://www.energy.gov/ne/articles/triso-particles-most-robu...

Reactors in general produce 3 types of waste: - fission products: after a Uranium or Plutonium atom splits, the daughter atoms are virtually always radioactive; the vast majority of these atoms have a half life of less than 100 years - actinides: Uranium and Plutonium absorb a neutron but don't undergo fission. The resulting atoms, heavier than U or Pu, are part of the Actinide group, and they are quite nasty - unburned fissile material: no reactor has a 100% efficiency, a part of the U235 or Pu239 is left unburned - low and intermediate level waste: various materials inside and around the reactor, which either absorb neutrons and become "activated", i.e. radioactive, or simply get mixed up with particles of the first 3 categories. Fast reactors produce very little actinides. Maybe 1-2% of what regular reactors produce. They also burn much more of their fuel, so there's less waster of the third category. The coolant in various fast reactors is sometimes Sodium. Sodium very rarely becomes activated, and when it does, it transmutes into an element with half life of 15 days, which then decays into a stable isotope. So, after a few years, what's left is not radioactive anymore. If however, the coolant gets contaminated with particles from the nuclear fuel, then it becomes more complex. For modern reactors, the Department of Energy envisions using Triso fuel, which they consider to be virtually indestructible [1]. If that is so, then the coolant in sodium-cooled fast reactors can be considered a very law level waste. Another type of waste is the structural steel around the core subjected to the neutron bombardment coming from the core. That steel, when activated, transmutes into some isotopes that have a half-life of decades, so that's a bit nasty. That's not specific to fast reactors, it's something in common with regular reactors. [1] https://www.energy.gov/ne/articles/triso-particles-most-robust-nuclear-fuel-earth https://www.energy.gov/ne/articles/triso-particles-most-robu...