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

Why Does The NRC Have an Official Historian?

Historial photo of President Carter
Historical photo

As the relatively new historian for the NRC, I am interested in blogging so I can talk directly with the public about the history of nuclear power regulation. In this first post, I’ll introduce you to the agency’s history program, give a little of my background, and offer my plans for future posts.

Established in 1977, the NRC’s history program is almost as old as the agency itself. Many federal agencies employ historians for a variety of archival and public outreach tasks, but the NRC set itself apart by committing its historians primarily to research and writing accurate, scholarly histories of the agency and its predecessor, the Atomic Energy Commission.

To meet the standards of the history profession, the Commission made it clear early on that its historians were to “be free to express scholarly opinions.” It is a commitment that has worked well. Under my predecessor, J. Samuel Walker, the history program produced numerous well-regarded articles and five books, including a widely popular account of the Three Mile Island accident.

The NRC historian also provides historical background for reports, responds to Commissioner, staff, and public inquiries, and is available for public presentations on agency history.

Although new to the position, I’m not new to history or nuclear power. After receiving my B.S. in mechanical engineering, I tested nuclear reactors on submarines for General Dynamics in Groton, Connecticut, and worked as an engineer at the Davis-Besse Nuclear Power Station near Toledo, Ohio.

My career then took a different, but not unrelated, professional direction. I earned a Ph.D. in U.S. history from the University of California, Berkeley in 1995. To understand the citizens protesting outside of the power plant fence, I wrote my first book on the history of the antinuclear movement, Critical Masses: Opposition to Nuclear Power in California, 1958-1978 (University of Wisconsin Press, 1997). Before coming to the NRC, I was a history professor and wrote on the history of nuclear power and environmental issues.

I am currently researching the history of the AEC and NRC in the 1970s. In future blog posts, I’ll mark the anniversaries of key agency events, discuss material from my ongoing research, and respond to reader inquiries. Let me know if you have a topic you’d like me to address by commenting on this post.

Tom Wellock
NRC Historian