Iran nuke spill coverup?

This article alleges that a nuclear spill at the Ayatollah Ruhollah Khomeini airport is the reason that the airport has been closed. According to the story the nuclear material came from North Korea (where else) and was cleaned up by Iranian scientists working only at night. The airport remains closed because the Iranians are afraid that radioactivity might still be detected there. I don't know if this story is true or not. I am sure that Iran wants to be a nuclear power, they are engaged in clandestine programs to achieve that goal, and they will eventually succeed unless something causes them to change their goal.