Schellhase 2025 Midwest & Southeast: 21 Aug 2025 - Oak Ridge and the Manhattan Project (long)

Today we visited Oak Ridge TN and the surrounding area. I knew Oak Ridge had ties with the Manhattan Project and our nuclear history, but I did not know how all the pieces fit together. I had identified several sites here to possibly visit, but we kind of hit the jackpot today. The Department of Energy offers a tour of the various sites here but when I checked on it there were no available seats. The tour leaves from the American Museum for Science and Energy (AMSE) which is one of the places I wanted to visit anyway. So we went a bit early this morning, driving 17 miles to Oak Ridge TN just in case a couple seats opened on the tour. Well it just so happened there was one no-show and they "created" another seat so the two of us could go. Yes!

Disclaimer: The following is my understanding based on what we saw and what we were told. I gave up on getting a nuclear physicist degree right after I gave up on becoming a brain surgeon!

To understand the significance of Oak Ridge, we need to understand the Manhattan Project: In 1939 Albert Einstein wrote a letter to President Roosevelt about Germany developing an "extremely powerful bomb of a new type" and advised the US to accelerate research on nuclear chain reactions. The Manhattan Project resulted and was a top-secret effort during World War II to develop the first atomic bombs. J. Robert Oppenheimer was appointed as the Scientific Director overseeing the entire project. It involved the smartest scientists, engineers, and military personnel across multiple locations, including Los Alamos NM, Hanford WA, and Oak Ridge TN, and resulted in the creation of the world's first nuclear weapons. The project's culmination was the bombing of Hiroshima and Nagasaki in Japan in 1945, which brought about the end of World War II.

Oak Ridge TN was created because of the Manhattan Project, and it was built unbelievably fast starting in 1942, but why Oak Ridge TN? Actually the location started as the Clinton Engineer Works. This location was home to a few farm communities. On display was a letter from the War Department to one of the local farmers, dated 11 Nov 1942 directing them to move by 1 Dec 1942! They were compensated, but that was less than a month!

The Tennessee Valley Authority had constructed dams providing ample electrical power. There were two railroads to transport materials and long with roads supporting buses, trucks and other vehicles. Water was abundant from the Clinch River. Most importantly the geographic location provided natural security and isolation in case of a large scale nuclear disaster.

Oak Ridge was considered :The Secret City". In just over 2-1/2 years it was built and over 75,000 people worked round the clock at classified sites throughout the city. We visited some of those sites today. Security was extremely tight. No one knew what anyone else did. Oak Ridge TN was not on any maps until 1949. The construction scope and speed were beyond comprehension. Massive housing was needed. Schools were needed. Stores, pharmacies, recreation, etc, not to mention the huge enrichment facilities to create the nuclear materials.

What did they do here? What was the goal? To enrich uranium for use in a nuclear weapon. Specifically, Uranium contains two isotopes: U-235 and U-238. “Enrichment” meant increasing the proportion of U-235, relative to U-238, in a uranium sample. This required separating the two isotopes and discarding U-238. They figured out primary ways to do this, and they built facilities here to accomplish this:

K-25 Gaseous Diffusion (the most efficient)
-- Uranium hexafluoride gas was forced through a series of porous barriers. The lighter U-235 molecules diffused through the barriers slightly faster than the heavier U-238.

Y-12 Electromagnetic Separation using Calutrons
-- Uranium was vaporized and ionized, then passed through a magnetic field. The lighter U-235 isotope was deflected more by the magnetic field, allowing for separation.

S-50 Liquid Thermal Diffusion (least efficient)
-- This method involved heating uranium hexafluoride gas and separating the isotopes based on their tendency to move towards the hot or cold side of a container.

X-10 Graphite Reactor
We also visited the Oak Ridge National Laboratory where the X-10 Graphite Reactor was. It is in the process of being cleaned up so we could not visit the reactor. It was the first continuously operated nuclear reactor

We departed the AMSE about 0900 hrs and headed about 12 miles southwest to the K-25 History Center. This facility was built and was the largest building in the world at the time (I hope I got that right)!

In K-25, as explained above, they used a process called "Gaseous Diffusion" to extract the U-235 isotopes. The facility is gone, but the footprint remains. They are constructing a new building that will allow visitors to see the huge footprint of K-25 and learn more about the process. The current K-25 History Center has many displays and information.

From here we moved to the Oak Ridge National Laboratory, where the X-10 Graphite Reactor was. The building we stopped at houses the Frontier exascale Super Computer. Exascale computing refers to computing systems capable of calculating at least 10 to the 18th power IEEE 754 double precision (64-bit) operations (multiplications and/or additions) per second. This computer occupies 7300 SF and is one of the most powerful in the world. It is water cooled.

We also saw a timeline of projects worked by the Oak Ridge National Laboratory. Amazing!

Next stop was the Y-12 Welcome Center. The facilities at Y-12 used the electromagnetic separation process to enrich the Uranium. A device called a Calutron accomplished this. These devices were operated typically by females who were never told what they were doing, only to watch the gauges and adjust the knobs accordingly.

There was a lot more information presented in here which a lot more pictures, but we will move on, actually back to where we started at the American Museum of Science and Energy.

This museum offers many educational, hands-on and visual displays. They had a movie that further explained the various facilities and the processes here. They also had 3D printed items such as a beautiful World War II-era Jeep and a car: