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Putting the Axe to the ‘Scram’ Myth

The NRC glossary defines a “scram” as “the sudden shutting down of a nuclear reactor usually by rapid insertion of control rods.” But where did the word come from? One deeply engrained legend about the origin of the word dates to the first sustained chain reaction on December 2, 1942, at the Chicago Pile (CP-1), the first atomic reactor developed for the Manhattan Project. According to the legend, Enrico Fermi created the acronym, Safety Control Rod Axe Man, for Norman Hilberry. It was Hilberry’s assignment that day to kill a possible runaway reaction by using an axe to cut a rope to allow the backup safety control rod to drop into the pile.

The axe-man story now has a life of its own. A search on Google for “scram” and “axe” yields 124,000 hits. Even the NRC’s glossary attributes scram’s etymology to the axe man story. Eleven years ago, Oak Ridge National Laboratories reported a fanciful variation of this story where Fermi, presumably unimpressed with the physical prowess of his fellow physicists, recruited a lumberjack from the Pacific Northwest to do the job. That version has now spread on the internet, and the acronym itself has mutated into Super-Critical Reactor Axe Man and Start Cutting Right Away, Man.

Hilberry, as it turns out, only learned the story second-hand years later, which lends doubt to the axe-man version, and Hilberry’s own recollection of the event didn’t accord with the memories of several other participants. Leona Marshall Libby, the only female physicist present that day, wrote in her memoir that it was Volney “Bill” Wilson who called the safety rods “scram rods.” She didn’t explain why, but her crediting the term’s invention to Wilson was supported by others involved in CP-1, including Warren Nyer.

I contacted Nyer recently, and he was eager to tell the “scram” story, one that squares well with Wilson’s reported version of events. Nyer’s job that day was to be Hilberry’s backup. If all safety systems failed, he and the other members of the “suicide squad” were to dump a liquid cadmium solution on CP-1 to poison the reaction. The axe-man story is, he recalls, “a bunch of baloney.” But he did offer another explanation for the word. His recollection was that Wilson was assembling a panel that included a big red button. According to Nyer, someone asked Wilson the reason for the red knob. Wilson replied you’d hit it if there was a problem. “Well, then what do you do?” he was asked. Wilson reportedly replied “You scram … out of here.” The word appears to have stuck.

And so it seems likely that scram switches all over the world owe their names not to the nuclear industry’s later penchant for acronyms, but to the slang of twentieth-century America.

Tom Wellock
NRC Historian

28 responses to “Putting the Axe to the ‘Scram’ Myth

  1. George Fredlund (@GeorgeFredlund) April 9, 2013 at 2:10 pm

    I remember reading a book about Rickover where the Chalk River story is told. But I also remember Ens. Pulver kicking the Captain’s hatch open and asking “What’s all this crud I hear about no movie tonight?” That happened after Mr. Roberts death.

  2. Dean Dillinger May 19, 2011 at 10:14 am

    Will: It is claimed that the term “crud” originally stood for “Chalk River Unidentified Deposit”, used to describe the radioactive scaling that builds up on internal reactor components, first observed in the NRX facility.[5] However, crud can also stand for “Corrosion Related Unidentified Deposit” and similar expressions. However, origin of the word “crud” is a Middle-English term from the word “curd” that is from about the 12th-13th century, so it’s use as a description for radioactive scaling is at-best a “backronym.”

    • Moderator May 19, 2011 at 1:07 pm

      As you point out, the word “crud” existed well before Chalk River. In the 1920s it was a slang expression for venereal disease. G.I.s in World War II commonly used the word for many diseases. The word was also used to denote corruption during World War II. So it seems likely that the nuclear industry appropriated the word, and the acronym followed.

      Tom Wellock

    • Will Davis May 19, 2011 at 7:19 pm

      Dean, that’s exactly the story I’d heard behind the acronym… it makes it even hard to use the term “crudburst” without a smile now and again. However, it does seem now that the term isn’t a true first-generation acronym, but an appropriated one. Still, the fact that one of the two acronym stories I learned early on is probably true is interesting in itself.

    • Anonymous March 22, 2013 at 6:25 pm

      I don’t know if you are a nuke or not but crud is officially defined in one of the many T- manuals used. I’d tell you what it is but is Confidential-NOFORN.

  3. Will Davis May 18, 2011 at 6:50 pm

    Well this helps put that old story to bed… doesn’t it? I first heard the story of how this came about in my first Navy school, I think.

    Please tell me that my favorite acronym… CRUD … is what I think it is. That would be shattering if it were not. (Chalk River Unidentified Deposits.)

  4. Moderator May 18, 2011 at 9:19 am

    Thank you so much for reading and responding to my post! I do have the sources Mr. Dunlap mentioned. Murray’s article, “The Etymology of ‘Scram,'” is the key source for the axe-man version of the word. It relies on Hilberry’s letter where he recalls his version of events many years later. However, people are often not aware that Nyer wrote a letter in response to Nuclear News disputing Hilberry’s story. Admittedly, this is a battle of memories, but I believe Nyer’s version for two reasons:

    1) Nyer confirmed his recollection of events with two other CP-1 veterans, including Bill Wilson.

    2) Nyer and Wilson worked alongside each other daily in the construction of CP-1, and Nyer recalls being present when Wilson made the “scram” comment. Hilberry, according to Nyer, worked in administrative tasks on the project in a building away from the stadium and was unaware of the inside jokes that developed among the students, such as Nyer, working in the squash courts to assemble the pile. Hilberry only learned that he was called the “scram man” a number of years later.

    I should add that Hilberry did hold an axe that day (that part of the story is true), but the word scram has nothing to do with it.

    Tom Wellock

  5. J. M. Floyd May 18, 2011 at 8:00 am

    I need to know whether I have been living a (SCRAM) lie! I pray the NRC Historian will review these comments, conduct additonal research, and post an update soon.

    As Mark Twain (sorta) said:
    Those who do not read newspapers (and blogs) are uninformed.
    Those who do….. read newspapers (and blogs) are misinformed.

  6. duxx May 17, 2011 at 10:19 pm

    I have been amused by the use of acronyms in this industry. ATWS (Anticpipated Trip Without Scram)
    was an acronym built in part with a (now debunked) acronym.

  7. Larry Dunlap May 17, 2011 at 2:07 pm

    I have electronic copies of a document called “The First Pile” which is a reprint of an official AEC document USAEC Report TID-292 original printing in March 1955 written by Corbia Allardice and Edward R Trapnell which describes the Axe Man. Additionally several Nuclear News articles, specifically “CP-1: The story of the first nuclear reactor” from the November 1992 issue of Nuclear News and “The etymology of “scram”” by Raymond L. Murray from the August 1988 issue of Nuclear News both of which discuss the “Axe man”. As of August 2010 Mr Murray was currently a resident of Springmoor Retirement Center in North Raleigh NC. In his article he cites a reference to a personal letter from Mr Hilberry to himself tha may corroborate the Axe Man. If you like I can send pdf versions of all three of these documents to you for your research.

  8. Gary Callaway May 17, 2011 at 2:07 pm

    When part of a license class at Palo Verde in ~ 1984, Arizona Public Service contracted fundamentals training to Memphis State University. They povided a doctor Vogel (sp?) to teach us the biological effects of radiation. The good doctor had spent his carreer at Oak Ridge studying this and had performed many of the experiments that led to our current understanding. He regaled us with wonderful stories from his long carreer and then tested us as if we were medical students. I wouldn’t have traded the experience for an easier class.
    I would estimate his age to be at least 70 when he taught our class. He said he was part of the team that achieved the original criticality. On a break, I asked him about the axe man and he said that there was, indeed, an axe man. He told me the person’s name, but i did not recognize it, so I forgot it. He also said that the provision was useless. They did not know that a “runaway” reactor would not have allowed time for such a crude intervention, but it seemed like a reasonable precaution at the time.
    I didn’t know him well enough to know if he was pulling my leg, but his response seemed to be serious.

  9. Mark Twain May 17, 2011 at 12:24 pm

    Yeah, I had Dr. Norm Hilberry for an NE course in 1982 at the University of Arizona. I seem to recall (I can probably dig up my class notes) him telling us about the cadmium solution. OTH, another NE prof. called him the “Axe Man”. Hmm, time to find those class notes…

  10. William Tucker May 17, 2011 at 12:21 pm

    I guess I’ll have to go back and edit my book, Terrestrial Energy. I put the swining axe story in there.

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