At the museum site for the EBR-1 reactor are the two experimental nuclear jet engine reactors. These were intended to develop a way to operate nuclear-powered bombers that would not have to land for days at a time.
View of HTRE 3 Nuclear jet engines
So what’s going on here?
The reactor is the big white blocky structure on the left, while the exhausts of the twin jet engines can be seen sticking out to the right.
Normally a jet engine has a compressor, a combustion chamber, and a turbine driven by the exhaust which also provides the thrust. The turbine is on the same shaft as the compressor stage, and powers it.
On the HTRE 3 we can see how the compressor stage feeds into a large pipe that runs up to the reactor, at about a thirty degree angle, and then another larger pipe going straight down carries the heated air to the turbine and exhaust nozzle. Functionally, the reactor is inserted into the jet’s power path as a sort of outside ‘combustion’ chamber for heating the air.
HTRE 2 and 3
HTRE 2 was rebuilt from HTRE 1, and then HTRE 3 was an entirely new construction. The display says that the experiments reused the one pair of jet engines, currently mounted on HTRE 3. However I have more recently heard (December 2023) that the engines from HTRE 2 were too contaminated for the display, and rather than those having been reused, new ones were built for HTRE3.
One might speculate that rising radioactivity in the turbojets would have led to a redesign to limit the problem.
Rumours persist that an actual plane was built, and lies elsewhere at the INL site, but certainly nothing ever flew with these engines.
The rumour may be based on the Convair NB-36H, which was powered by conventional engines, but carried a small reactor in its bomb bay for purposes of testing crew shielding and other technologies.