Allow me to get pedantic for a bit: What is labeled on the purpose of the car to carry - steam generator, should be steam turbine generator (SSTG). A steam generator (S/G) for a reactor is something completely different; it's large upright, cylindrical heat exchanger, used to isolate the reactor/primary from the steam/secondary side in a pressurized light water reactor. The only time you'd possibly see an S/G on a railcar is in shipment to a shipyard for new construction (Electric Boat in Groton or Newport News in VA), they last the life of the reactor plant, and are disposed with the whole reactor compartment which is cut out of the boat/ship.
Trivia: of the 32 S/Gs on the USS Enterprise, many of them were made by Alco.
Before the newer cask, four truck cars, spent cores were shipped to Idaho in USN depressed center flatcars, two truck, that had a large cylinder, braced with four angled supports /||\
ex-Navy nuke