Patent Number: 
Section: claims

1. A method of operating a nuclear fission traveling wave reactor, the method comprising:migrating at least one nuclear fission fuel assembly in a first direction from a first location in a nuclear fission traveling wave reactor core to a second location in the nuclear fission traveling wave reactor core, the second location having predominantly nuclear fission reactions and being different from the first location; andmigrating the at least one nuclear fission fuel assembly in a second direction toward a propagating wave burnfront in the nuclear fission traveling wave reactor from the second location to a third location in the nuclear fission traveling wave reactor core, the third location having predominantly nuclear absorption reactions, and the second direction being different from the first direction. 2. The method of claim 1 wherein the operation of migrating the at least one nuclear fission fuel assembly from the first location to the second location further includes crossing the propagating wave burnfront, and the operation of migrating the at least one nuclear fission fuel assembly from the second location to the third location further includes crossing the propagating wave burnfront. 3. The method of claim 1 wherein the first location is radially inward from the second location.