< jargon > (From the nuclear power industry) An emergency power-off switch (see Big Red Switch ), especially one positioned to be easily hit by evacuating personnel. In general, this is *not* something you frob lightly; these often initiate expensive events (such as Halon dumps) and are installed in a dinosaur pen for use in case of electrical fire or in case some luckless field servoid should put 120 volts across himself while Easter egging .
SCRAM stands for Safety Control Rod Ax Man. In the early days of nuclear power, boron moderator rods were raised and lowered on ropes. In the event of a runaway chain reaction, a man with an axe would chop the rope and drop the rods into the nuclear pile to stop the reaction.
See also molly-guard , TMRC .
[ Jargon File ]
(2003-05-17)