Most of my life I have thought this myself. I did not know that it was extremely heavy. The dirty bomb part I knew in my late 20's. That part became even more obvious after 9/11 and went down a rabbit hole of the USSR nucking on of their own villages/towns to have a war game. I mean seriously, if we sent all of our nuclear waste to the sun it would add a whole .000000135 seconds to the life of the sun. Now I just learned, reading the responses to this query, about delta V, whatever the hell that is, is an issue.