| CPC F02K 9/42 (2013.01) [G21C 1/06 (2013.01); G21D 5/02 (2013.01)] | 20 Claims |
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1. A method comprising:
during a first time period at a nuclear rocket engine:
by a pump, pumping a propellant:
from a propellant reservoir at a supply temperature;
through a cold side of the pump;
to a set of moderator coolant channels, extending axially within a moderator, to cool the moderator;
to a hot side of the pump to operate the cold side of the pump;
through a set of fuel elements to heat the propellant to a first outlet temperature, the set of fuel elements extending axially within the moderator and isolated from the set of moderator coolant channels; and
out of a thrust nozzle to produce a first thrust; and
locating a reflector, arranged about the set of fuel elements and the moderator, at a first closed position to reflect neutrons toward the set of fuel elements to maintain a fission rate of the set of fuel elements above a threshold fission rate;
during a second time period:
locating the reflector at a second open position to release neutrons from the nuclear rocket engine and to reduce the fission rate of the set of fuel elements to below the threshold fission rate;
by the pump, pumping the propellant:
from the propellant reservoir at the supply temperature;
through the cold side of the pump;
to the set of moderator coolant channels to cool the moderator;
to the hot side of pump to operate the cold side of the pump;
through the set of fuel elements to cool the set of fuel elements and to heat the propellant to a second outlet temperature less than the first outlet temperature; and
out of the thrust nozzle to produce a second thrust less than the first thrust.
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