Labor, secrecy culminated with Graphite Reactor's 1943 startup.
Sunday, Nov. 4, 2018, is the 75th anniversary of the Graphite Reactor, as it came to be known, reaching criticality for the first time on a morning in 1943. The Graphite Reactor is the first nuclear reactor facility built as such -- its predecessor, where the first controlled nuclear reaction occurred, was essentially a stack of graphite blocks carefully arranged by Enrico Fermi in a University of Chicago squash court.
Legend has Louis Slotin racing into the new settlement of Oak Ridge to notify Clinton Laboratory managers Martin Whitaker and Richard Doan that the moment had arrived. In 2003, the 60th anniversary year of "critical reached," Steve Stow interviewed Manhattan Project veterans Art Rupp and John Gillette, who were present in Bldg. 3001 on the historic day, for ORNL's oral history series.
STOW: I think both of you gentlemen were present on November 4th of 1943, when the Graphite Reactor went critical. Did you have special feelings at that moment when you recognized what was going on or were you so busy with the control rods that you didn’t know what was happening?
GILLETTE: That was the end when it went critical. We knew it was gradually building up energy. It was no surprise when it went critical. There was a question of whether it would go critical. I had the feeling that the guys who designed the reactor knew what they were doing. There might have been some untoward thing that would stop it but I was confident it was going to go.
RUPP: Yes, I was there.
STOW: Art, tell me a little bit about what your thoughts were, and whether you realized the magnitude of that event.
RUPP: Yes, I did recognize the magnitude of the event, and it was almost one of total amazement. But, I had a great deal of faith in the team of nuclear physicists under Enrico Fermi, who were doing all the physics work for the Graphite Reactor. [Fermi led the team that achieved the world’s first sustained chain reaction at the pile under Stagg Field in December 2, 1942.] I was fairly sure that it was going to work. But, actually, there was a little incident, right at the beginning, after John and the other fellows had put all the rods in the channels. They tried to start the critical reaction, to make the reactor go critical, but the reactor didn’t start. There was a great deal of confusion about that for a short time. Then, it was realized that the reactor had retained some moisture. And, water, of course, is a great absorber of neutrons. We couldn’t get the reaction going, so we ran the reactor with some heaters to get it all dried out. It was an air-cooled reactor. Finally, we got the moisture all cleared out and down to a satisfactory level. When we retried starting the reactor, it did begin to produce neutrons and heat. That was a great relief.
STOW: I'm sure it was. John, what were your thoughts when all this was going on?
GILLETTE: Well, the technical group in the chemical separations area was told that we were going to load the reactor [with uranium fuel]. We were split up into two groups -- two twelve-hour shifts. The first group started at 8:00 in the morning, loading the slugs [of uranium] that the reactor group had in boxes. All of the slugs had been tested for leaks, and all had been numbered. They had programmed which slug was going into which channel ...
STOW: Yes.
GILLETTE: ... and where in the channel. So, they told us how to load the thing. All we did was to take the slugs and they said, “Okay, we’re working on this, and you’re going to work on this particular channel.” To put them in, they pulled the plug out from the shield. There was a channel that went through the plenum chamber into the graphite. The slugs then were put in a little channel on the outside so that we could put a rod behind them and push them through, into the reactor. The reactor group again measured the reactor gain. Somebody said, “Okay, that’s where it should go.” They knew how many feet into the reactor each slug should go. And, the loading started very slowly. As Art says, there was a point where things didn’t look right, and they had to dry the reactor out. So, the first shift loaded, I guess, only two or three tons of fuel. And, when I came in at eight o’clock at night, they were still loading a few slugs, stopping, and taking measurements to make sure everything was going okay. Eventually, the reactor went critical in the morning [around five o’clock].
STOW: Were you aware of the fact that you were trying to produce plutonium for an atomic bomb?
GILLETTE: Yes.
