scram switch

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)