Even in a simpler system that trades a steam turbine for a simple heat engine, excess thermal energy must still be shed, which a combustion engine does as part of its normal operation.
“For an ICE, much of the waste heat is disposed of via the exhaust gas, and what is left is handled by the radiator,” continued Dr. Thomas. “Since the nuclear reactor’s working fluid is not exhausted, but rather recycled (think of your home or auto air conditioner), the waste heat must be dumped via one or more radiators.”
“It is all these other elements of the system to handle the energy conversion and dispose of waste heat, which present the challenges to use of a nuclear reactor in a personal vehicle.”
For these reasons, nuclear power on the scale of a personal vehicle simply wasn’t possible back in the day, and at any scale of production the likes of Ford entertain today, it still isn’t.
“Mobile nuclear power on such a small scale was not feasible in the ’50s,” Dr. Thomas concluded. “And not due to the small reactor itself, which we do now understand how to construct and control—refer to NASA’s KRUSTY project—but rather the thermal-to-mechanical energy conversion and disposal of waste heat within the geometrical envelope of a personal vehicle. Also, with the Department of Energy‘s Small Modular Reactor Program, the nuclear industry is figuring out how to mass-produce nuclear reactors.”
“[Ford] likely optimistically assumed that energy conversion technology would improve significantly (we’re still chasing energy conversion breakthroughs today), and the geometry of the concept vehicle leads me to speculate that they [would have] had a lot of radiators stashed under that sheet metal.”