The Collaborative International Dictionary of English v.0.48:

Scram \Scram\ (skr[a^]m), n.
   the rapid shut down of a nuclear reactor, as in an emergency.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Scram \Scram\ (skr[a^]m), v. i. [imp. & p. p. Scrammed; p. pr.
   & vb. n. Scramming.]
   to leave; to go away; used mostly as an impolite command to a
   person to go away from a specific location. [informal]
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Scram \Scram\ (skr[a^]m), v. t. [imp. & p. p. Scrammed; p. pr.
   & vb. n. Scramming.]
   to shut down (a nuclear reactor) quickly, as in an emergency.
   [PJC]

WordNet (r) 3.0 (2006):

scram
    v 1: leave immediately; used usually in the imperative form;
         "Scram!" [syn: scram, buzz off, fuck off, get,
         bugger off]