The Collaborative International Dictionary of English v.0.48:

nuclear explosion \nuclear explosion\ n.
   The explosion of an atomic bomb or atomic device; --
   sometimes also used of fusion-powered explosions.

   Syn: atomic explosion.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

nuclear explosion
    n 1: the explosion of an atomic bomb [syn: nuclear explosion,
         atomic explosion]