Pulsed nuclear thermal rocket

A pulsed nuclear thermal rocket is a type of nuclear thermal rocket (NTR) concept developed at the Polytechnic University of Catalonia, Spain, and presented at the 2016 AIAA/SAE/ASEE Propulsion Conference for thrust and specific impulse (I_sp) amplification in a conventional nuclear thermal rocket.^[1]

The pulsed nuclear thermal rocket is a bimodal rocket able to work in a stationary (at constant nominal power as in a conventional NTR), and as well as a pulsed mode as a TRIGA-like reactor, making possible the production of high power and an intensive neutron flux in short time intervals. In contrast to nuclear reactors where velocities of the coolant are no larger than a few meters per second and thus, typical residence time is on seconds, however, in rockets chambers with subsonic velocities of the propellant around hundreds of meters per second, residence time are around ${\displaystyle 10^{-2}s}$ to :${\displaystyle 10^{-3}s}$ and then a long power pulse translates into an important gain in energy in comparison with the stationary mode. The gained energy by pulsing the nuclear core can be used for thrust amplification by increasing the propellant mass flow, or using the intensive neutron flux to produce a very high specific impulse amplification – even higher than the fission-fragment rocket, wherein the pulsed rocket the final propellant temperature is only limited by the radiative cooling after the pulsation.