Few cities have a larger quantity of mysterious and cryptic names than the "secret city" of Oak Ridge. Founded in 1942 as the home of the top secret Manhattan Project that enriched uranium for the first atomic weapons during World War II, nearly everything in Oak Ridge was cloaked with code names.
Now more than 60 years after the gates of the secret city opened to outside world in 1949, the legacy of code names remains a prevalent sight for the public. Facilities with names such as K-25, Y-12, and X-10 are commonly used terms for locals throughout East Tennessee.
But why did they name the various plants with these strange combinations of letters and numbers? Do the letters and numbers have any meaning?
You will not find many people with more knowledge about Oak Ridge than resident Bill Wilcox. Wilcox moved to Oak Ridge as a 20-year-old chemist in 1943 and has lived in the city ever since. Through the decades he worked his way up to the rank of technical director of research and development for both Y-12 and K-25. Today Wilcox serves as the official historian of the City of Oak Ridge, an honor bestowed upon him by the city council.
Wilcox remembers exactly when he heard the name "Y-12" for the first time.
"It was in 1943 on the day I came to work. I was excited to finally get to this place in Tennessee that they would not tell us anything about," said Wilcox. "They told us to go to the bus station and to look for a bus that said 'Y-12.' The bus station was full of buses going to places like 'K-25' and 'X-10.' That was a great puzzle."
Wilcox and others did not ask any questions about these military designations. Everything from the main facilities, the chemical compounds, to the employee dormitories had a code-name and the monikers became a normal part of life.
"You get used to it very quickly," said Wilcox. "We didn't know what any of the other plants were doing and they didn't know what we were doing at Y-12. You just focus on the job you have before you and know not to ask questions about or go to places that don't have anything to do with your own task."
What Wilcox and thousands of other scientists were doing is trying to enrich uranium into weapons-grade U-235. Enriching uranium was the task of Y-12 and K-25 while the X-10 plant served as the site of a Graphite Reactor to produce plutonium.
"We knew the uranium was for the war effort but we did not know exactly how the military was going to use it until August 6, 1945. That's when we dropped the bomb on Hiroshima. Out of the 75,000 or so employees in Oak Ridge, I'd bet around 72,000 did not have the slightest idea they were working on a nuclear bomb."
After the war when the secret city was not a secret anymore, people felt comfortable enough to openly guess at what the code names X-10, Y-12, and K-25 stood for.
"The first reaction that almost everybody had is that they must be map coordinates. I actually tried to draw a map and it made no sense at all," said Wilcox.
The letter 'X" in X-10 does not mark the spot for anything on a map of Oak Ridge. In fact, the names for both X-10 and Y-12 do not stand for anything.
"They were intentionally picked as random numbers to give nobody any kind of clue as to where the plants were or what they did," said Wilcox.
Major General Kenneth Nichols attempted to answer the question concerning the X-10, Y-12, and K-25 designations in a letter dated October 17, 1949.
"There is no information anywhere in the Manhattan District History of the origins of the designations of the plutonium, electromagnetic, and gaseous diffusion projects, X-10, Y-12, and K-25," wrote Nichols.
Nichols speculated that the letter designations X and Y "were adopted as the most familiar mathematical symbols for unknowns, but no clue to the numbers '10' and '12' can be imagined."
The same could be said about a fourth plant in Oak Ridge named S-50. Its letter and number designation were entirely arbitrary. Of all of the Manhattan Project facilities in Oak Ridge, only K-25's name has any rational explanation.
"The 'K' stands for the Kellex Company that designed the plant in New York," said Wilcox. "The 25 is shorthand for U-235. They left the three out and just called it 25. This designation really upset some of the Army leaders since it could potentially lend a clue about the origin of the plant. The Army was going to have them change the name, but decided against it because they thought that would just attract more attention to the name and have people wondering what was significant about that designation."
In 1947, X-10 changed its name to the Oak Ridge National Laboratory. K-25 changed its name a few times before it closed. S-50 was torn down shortly after the war. Y-12 is still Y-12.
"Of all the Manhattan Project facilities all over the U.S.A., Y-12 is the only one still called by its wartime name," said Wilcox. "The question about these names keeps coming up because it is so intriguing. I hope that they keep asking the question because it gives us a chance to tell a little bit more about how Oak Ridge helped win the most terrible war in history. Then we directed that technology towards solving the problems of mankind with things like nuclear medicine. That's a great legacy to have."
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