MyndkryM
SOC-3
Unless you want the ships to have hilariously-large radiators (and nobody wants that -- even Discovery from 2001, a Space Odyssey, which was pretty hard SF, had the heat radiators deleted because they'd've looked too much like wings and nobody would believe a hard-SF spaceship with wings...) And even then... nah.
I pretty sure most here are familiar with Atomic Rockets, http://projectrho.com/public_html/rocket/ If not....definitely check it out, because making real life atomic rockets has some challenges to say the least.
As you pointed out...heat, lots of and lots of heat. One of the interesting solutions is something called a Curie Point Liquid Drop Radiator.
Heat Radiators - Atomic Rockets
I could see something in Traveller using gravtics instead of magnetics, thus resulting in a smaller size device.