There are some other options like aerobraking in the thin Martian atmosphere, and the gravity of Mars helps capture the vehicle at the other end, so not that mu

There are some other options like aerobraking in the thin Martian atmosphere, and the gravity of Mars helps capture the vehicle at the other end, so not that much braking thrust is needed, and it's going to be fired at some complex angle: https://marspedia.org/Earth-Mars_Transfer_Trajectory https://marspedia.org/Earth-Mars_Transfer_Trajectory https://en.wikipedia.org/wiki/Hohmann_transfer_orbit https://en.wikipedia.org/wiki/Hohmann_transfer_orbit These types of rockets ideally shouldn't produce much radiation, as the working fluid (propellant) is just heated up by passage through the reactor, although I don't know if there's a primary coolant loop and a heat exchange or if it's just basically the primary coolant being blown out to space, in which case maybe there'd be some 3H-tritium formed? Probably not much of a concern, though it might be for a Earth-based test firing.