Etymology of SCRAM

["Carbaugh, Eugene H" <gene.carbaugh@pnl.gov>]

Detailed discussion on the origin of SCRAM in the nuclear reactor world
can be found in an article in Nuclear News (journal of the American
Nuclear Society),  August 1988.  Entitled "The Etymology of "SCRAM," the
author is Raymond L. Murray, professor emeritus of nuclear engineering
at North Carolina State U.  It also engendered a couple of interesting
letters to the editor, published in the December 1988 issue. 

To quote briefly from the article:  

"The best source of information on the derivation of "scram" is Norman
Hilberry, now deceased.  He was a member of Enrico Fermi's team on the
first reactor...In a January 1981 letter, he explains that on the
original pile, there was a shim rod going through the middle of the pile
and two safety rods, plus carboys of cadmium solution to be dumped on
the pile if a blue glow appeared.  A ;third safety rod was attached to a
rope over a pulley.  In the design sketches of the system, there was the
legend SCRAM, standing for Safety Control Rod Ax Man.  Hilberry had the
assignment of standing with the ax, ready to cut the rope if necessary.
He learned much later that his colleagues had called him "Mr. Scram." 

"Hilberry in his letter mused about the situation:  "I don't believe I
have ever felt quite as foolish as I did then.  Clearly if there was any
real reason for my standing there with that ax, we should not be doing
what we were doing - at least not where we were doing it.  The fact that
any misadventure there would almost certainly result in tipping off the
Germans as to what we were doing and how far we had gotten was at least
as worrisome as was any possible amage to our neighbor's health.
Concerned as we were with the absolute need for safety, we none of us
would have been there had we had any doubt as to the outcome."

"...There was no scientific excuse for the ax man.  The possibility of a
power failure, of course, dis exist but as I stood there it sure seemed
remote.  The argument then as now was if the scandalously remote should
occur and you had not taken every conceivable safety precaution, whether
reasonbly justifiable or not, you would certaingly be adjudged to have
been remiss.  The philosophical roots of some of our problems extend way
bact the our very early days."


A responding letter in the December 1988 Nuclear News from Warren E.
Nyer cited his personal correspondance with two members of the CP-1
instrumentation group, Hugh Barton and Volney Wilson.

"The word arose in a discussion Dr. Wilson, who was head of the
instrumentation and controls group was having with several members of
his group.  The group had decided to have a big button to push to drive
in both the control rods and the safety rod.  What to label it?  "What
do we do after we punch the button?" someone asked.  "Scram out of
here," Wilson said.  Bill Overbeck, another member of that group, said,
"Okay, I'll label it SCRAM."

Sorry for the lengthy response but I thought this bit of nostalgia worth
passing on.  

Gene Carbaugh
Internal Dosimetry 
Pacific Northwest National Laboratory
Richland, WA 

gene.carbaugh@pnl.gov