&quot;That much nuclear material&quot; as in &quot;enough to visit nearby star systems&quot;. Perhaps you&#x27;ve underestimated the literally astronomical distances involved, and how much power is required to get there in anything close to a reasonable time-frame. It would be required to accelerate at full speed for centuries, then turn around and decelerate for centuries more.  It&#x27;s easy to imagine that taking enough nuclear material to be able to cause a non-negligible nuclear disaster on a scale that meets or exceeds past nuclear disasters.  Fukushima and Chernobyl weren&#x27;t exactly trying to travel to another star system, after all.<p>Then again I might be completely wrong, but seeing as it&#x27;s <i>literally</i> rocket science, I think you can forgive my ignorance and I can forgive your condescending tone.