The hard part would be finding a buyer. North Korea already has their own domestic capability, and Iran is using their current situation as a negotiating point.

The hard part would be finding a buyer. North Korea already has their own domestic capability, and Iran is using their current situation as a negotiating point. Beyond that, who would even want black market nuclear fuel? It theoretically could happen at small scales though, eg. The Apollo Affair where Israel's nuclear program was allegedly kick-started by the illicit diversion of nuclear fuel from the US. https://en.m.wikipedia.org/wiki/The_Apollo_Affair https://en.m.wikipedia.org/wiki/The_Apollo_Affair