I would think Pyongyang would be the last place the North Korean regime would have to worry about using tanks to quell an uprising:

The North Korean Army’s Guard Command, a military unit tasked with protecting leader Kim Jong-il, is hiding scores of tanks in Pyongyang to quell any popular uprising, Radio Free Asia claimed Tuesday.

The U.S.-funded radio station quoted a defector from Pyongyang as saying, “There is a battalion of about 50 tanks from the Guard Command in the Taedong River area in eastern Pyongyang. They stage a field exercise about once a year.”

He said the tanks used to move only at the night to escape public notice. “All are hidden underground. I heard from families of officers of the tank battalion that there are also tanks in an underground near Moranbong,” a hill in downtown Pyongyang.

Kim Kwang-jin, another defector who works for the U.S. Committee for Human Rights in North Korea, said there used to be a battalion of tanks in an underground area beneath the Kumsusan Assembly Hall while Kim Il-sung was alive, but he was unsure whether it is still there.  [Chosun Ilbo]

If a revolt against the regime happens anywhere is would be in North Korea’s northeast rather than Pyongyang.  If anything tanks in Pyongyang would make it easier for someone in the military to launch a coup and an additional reason why I doubt all these tanks are sitting in Pyongyang.