Scored Plate Reactor for an Innovative Nuclear Thermal Rocket (SPRINTR)

The Scored Plate Reactor for an Innovative Nuclear Thermal Rocket (SPRINTR) is a novel approach to nuclear thermal propulsion which increases safety and reliability by partially reducing thrust. This is accomplished by altering the fuel from from traditional prismatic geometry into a flat plate geometry. Doing so allows for exposed flow channels to be coated in inert material to avoid midband corrosion, but reduces the the channel length and propellant mass flow. The result is a nuclear rocket that can achieve specific impulse values of >800s but half the thrust of a comparably sized prismatic engine.  Midband corrosion is a phenomenon which is often attributed as the major factor which prevented the NERVA program from producing a flight ready nuclear rocket. Hot hydrogen must be kept away from graphite based fuels, and this is accomplished with a thin layer of inert ZrC. However, that layer erodes over time in the extreme environment inside the reactor core, and minor variations in coating thickness, uncoated areas, or cracks in the layer, will result in exposed fuel which will quickly erode away at an exponential rate. By using a flat plate design, the ZrC coating can be thoroughly inspected before use.  The SPRINTR is assembled by stacking the flat plate fuel elements into a subcore which heats hydrogen gas for propulsion. Each fuel plate can be custom designed for its position to allow propellant flow to reach its maximum temperature based on the heating profile of the subcore. Outside of these subcores, a block moderator is used to allow for use of low enriched uranium. By using a block moderator instead of an in-core moderator, the propellant flow path is greatly simplified and does not require multiple passes of regenerative cooling. Additionally, the subcore design allows for simplified scaling for different sized engines, as subcores can be added or removed to accommodate needs.  No other nuclear thermal rocket design has been successfully flown in space, as the promise of high thrust and high Isp has proven too tempting for any researcher to sacrifice. The SPRINTR project's approach is that a modest decrease in thrust will have negligible effects on mission performance but will allow for a unit to actually fly. Thus, this project will result in the highest thrust and highest Isp nuclear rocket to ever operate in space.