fissionable

There's one moon, almost solid nickel iron, and fissionable-ore deposits.

Do you know why that planet was so extensively colonized by the Federation, when there don't seem to be any fissionable ores?

The neutron source, the neutron reflector, and one piece of fissionable material were in place.

What makes the whole thing terrible is that the freighter is loaded with fissionable material exported from Ganymede.

Randy and Manuel were already arguing about how much fissionable a freighter like that could carry.