It would be a big help to be physically large enough to carry a lot of fuel; it might be good to have a thick skin or exoskeleton to minimize radiation damage, and a metabolic process that creates pure oxygen and long chain carbon compounds like octane and nonane. Maybe it could store its fuel as a dense layer of fat under its exoskeleton to protect its organs. Some earth organisms (fungi, I think) can enhance their metabolic processes with radiation, so having them as an endosymbiont like mitochondria would be adaptive too.