I believe there are some newer theoretical reactor designs based around this concept! In essence, they are designed such that the fuel is not in itself capabl

I believe there are some newer theoretical reactor designs based around this concept! In essence, they are designed such that the fuel is not in itself capable of sustaining a chain reaction. It is only with the active addition of neutrons that you can get the fission reaction underway. So if you halt that supply of neutrons from the neutron generator, the reaction dies off, greatly enhancing passive safety.