Initially, we didn’t think we’d have time to visit Oak Ridge – our planned route took us on a comparatively leisurely drive from New York to Chicago with a stop in Pittsburgh for a night. But as the recommendations began to pile up, first from John Haggerty and the other physicists at Brookhaven, then Cindy Kelly of the Atomic Heritage Foundation, we realized that the additional visit to Tennessee would probably be worth it.
Oak Ridge was the site of the first nuclear reactor after Enrico Fermi’s successful chain reaction at the University of Chicago. Constructed during the early stages of the Manhattan Project, the Graphite Reactor was used to process plutonium for the first atomic bombs. A self-contained museum now, the reactor was never truly decommissioned – just ceremonially turned off about six months after a flood damaged it beyond reasonable repair. Myriad plans for the Reactor surfaced and dissolved as decades passed: a company was supposed to come in and fill the whole thing with concrete a few years ago; and there was a proposal to move the reactor face to a museum in the town of Oak Ridge. But today it sits as it ever did, still in cooldown phase, only intermittently accessible to the public since post-September 11th security measures limited access to the lab as a whole.
No radiation has been detected in the building for fifteen years, but in principle the reactor could be turned back on at any time. Of course, as our guide Fred Strohl put it, “technology has changed a little since then.” The reactor functioned on the barest of nuclear principles: workers would push rod-shaped chunks of uranium through holes in the reactor face with long sticks, a process not unlike the loading of an 18th century musket, until the critical mass of uranium was reached deep in the machine and the famous chain reaction would begin.
Amusingly enough, the first time that this happened at Oak Ridge was almost an accident. The bosses, M. D. Whitaker and R. L. Doan, had gone home for the night, not expecting the reactor to go critical until the next day. But they had overestimated the amount of uranium required and underestimated the zeal of their workers, who added fuel rods more quickly than the program had called for. Woken in the middle of the night, they gathered with their subordinates at the plant as the reactor burst into life.
After spending time in RHIC’s Main Control room, the control room for the graphite reactor was beautifully antiquated:
After the war, the Graphite Reactor was used to produce radioisotopes for basic physics research, medicine, agriculture, and industry. This periodic table indicates all the radioisotopes it was capable of producing:
While the Graphite Reactor is now firmly a part of physics history, another old machine is still contributing to science at Oak Ridge: the Oak Ridge Isochronous Cyclotron, or ORIC for short. While most cyclotrons were decommissioned long ago and turned into sculptures or scrap metal, ORIC has operated in various forms since 1962. It is currently part of the Holifield Radioactive Ion Beam Facility (HRIBF), helping to supply radioactive ion beams to several experiments.
The cyclotron room was the first area we’d visited that could potentially have exposed us to harmful radiation. One of our guides, Carl Gross leaned in as we approached the room, and said with a gentle seriousness that commanded particular attention: “try not to touch anything while you’re in there.”
To enter the room, we passed through the most intimidating door we’d ever seen. Metal, twenty feet tall and six feet thick, hung on hinges the size of a man’s chest, with the following message inscribed on the inside:
In the event that you are locked in
this room, depress red button
on this door or any of the
red buttons on the walls
This cuts off power
Leave red buttons all the way in
until cyclotron operator
opens the door
The cyclotron cannot be
operated while red buttons
After ORIC does its job, the already fast-moving particles are sped up even more by the tandem accelerator, a 100-ft. tall version of the Van de Graff generators that make your hair stand on end at science museums. This one would do much more than ruin your hairstyle if you went inside while it was turned on, however, so we didn’t get to ride the tiny elevator that takes one person at a time inside for maintenance.
We rode a far larger elevator up the outside of the tandem’s enclosure to take a look at the top of the accelerator — and the view of the lab from its roof.
The fully accelerated particles travel down several beam lines, one of which ends at the Recoil Mass Spectrometer. By running the beam through a momentum separator and a mass separator, the RMS team can isolate specific products of nuclear reactions and study the structure and behavior of atomic nuclei.
Other particles from the HRIBF are used to study the nuclear reactions that take place in novae and other stellar explosions. The experimental astrophysics group recently rescued the Daresbury Recoil Separator from the scrap pile in England to make precision measurements of certain products of such reactions.
(Incidentally, Michael S. Smith, the leader of the experimental astrophysics research group, also heads the Nuclear Data Project, a totally cool effort to collect and evaluate the latest research on nuclear structure and astrophysics. Its open source ethos encourages data sharing and tries to address the many problems that accompany secrecy in science by emphasizing the free and efficient flow of information. Since Nick wrote his undergraduate thesis on commercially imposed secrecy in biotechnology, we were particularly excited to hear about the issue in another field of science.)
Not everything at Oak Ridge is charmingly old, however. The lab is home to the National Center for Computational Sciences, and Jaguar, the second fastest supercomputer in the world. It also houses a stunning visualization wall that brings the lab’s research to life, allowing scientists to showcase their work and make connections that they might otherwise miss.
The Spallation Neutron Source is on the cutting edge of materials science, using neutrons to probe the structure of many different kinds of matter. Like the National Synchrotron Light Source, it is a user facility, and thus fundamentally interdisciplinary. It even helped disprove the hypothesis that President Zachary Taylor was assassinated.
Oak Ridge was an impressive mix of old and new, focused on preserving its history, adept at recycling machines that might otherwise have gone to waste, and dedicated to being a player in the interdisciplinary science that may well be the future of the National Labs. Thanks to Vince Cianciolo, Fred Strohl, Cindy Kelly, Jim Beene, Carl Gross, Alan Tatum, and Michael Smith for making our visit possible and for showing us their amazing work.
Next stop: Fermilab!
-text by Lizzie and Nick, photos by Nick