If North Korea is not testing nuclear warheads what are they doing that is picking up radaition signals?

Question

A couple days ago we thought to believe that North Korea has been testing there nukes underground. When Japanese airplanes came by there were no radiation signals what so ever. When are they testing that is making the big boom?

Answer 1

First you say they are picking up radiation, then you say they are not. I heard they is no radiation, which may imply an explosion with dynamite made to seem like a nuke. Either way, the N. Korean leaders are crazy

Answer 2

they are humping each other too hard which in result gives off radiation.