The term "most atom-powered" can be used to describe something that is primarily powered by atoms, specifically nuclear energy. However, there are several synonyms that can be used in its place. For example, "nuclear-powered" is another phrase that can be used to describe something that is primarily fueled by nuclear energy. Another possible synonym is "atomic-powered," which carries a similar meaning. Additionally, "radioactive-powered" or "isotope-powered" could be used to describe things that run on radioactive materials. When writing about energy production or technological advancements reliant on nuclear energy, it is important to use these synonyms effectively to convey an accurate and engaging message to readers.