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Robert Kupp’s Interview

Manhattan Project Locations:

Robert Kupp received mysterious orders to report to Knoxville, Tennessee just before he was shipped out to the Pacific Theater, and joined the Manhattan Project at Oak Ridge. He was assigned to work as a supervisor in the Line Recorder Department at the K-25 Plant. He discusses life at Oak Ridge and the security and secrecy involved in working on the project. Kupp went on to a prestigious career as a nuclear engineer.

Date of Interview:
June 17, 2006
Location of the Interview:


[Interviewed by Cynthia Kelly and Tom Zannes.]

Robert Kupp: My name is Robert William Kupp. Did you say spell it?

Yes. [Laughter.]

Kupp: Robert William K-U-P-P. And the age is eighty-two. I’ll be eighty-three next month in July.

So, Mr. Kupp, I wanted to know, what were you doing before you came to the Secret City?

Kupp: Well, I was in the Army in Texas taking and giving medical basic training, and I got there through a very strange route. In college, I originally enlisted in the Navy, in my first semester there, in the Naval Reserve program, to be, eventually, a deck officer in the Navy.

Well, after a year and a half in the Navy, still going to school—that was Wayne [State] University in Detroit—the Navy decided that I’m slightly colorblind, red-green. I could not past the Ishihara test to read the numbers. And therefore I was given a choice in the Navy of either taking a Navy discharge, or an apprentice seaman in the Seabees, six weeks of bulldozer, then off to a South Pacific island to run a bulldozer, which I did not join the Navy for.

So I collected the Navy discharge. I was eventually drafted, with one semester to go for my degree in chemical engineering. At the reception center—or at the induction center, —the lieutenant said, “Oh, chemical engineer, huh? Chemistry, that’s pretty close to medicine!” And so I was sent to Camp Barkeley, Texas, to the medical basic training.

At that time, medical basic, first part of that was, you were given military rifle training, because you were shooting at people in the South Pacific. And so we took that first, and then medical basic training. And I went on that way and then volunteered for a leadership school there, which was a pre-cadre.

In the meantime, I had been going to the various boards for Officer Candidate School, which I finally got to the bottom line of that, and got accepted to Officer Candidate School. Except—there’s always a “but”—except that the camp was closing, Camp Barkeley, and therefore they had no further quota for Officer Candidate School from that camp. 

Well, I was on orders for shipment with a buddy of mine who I’d been in the Army with ever since we were in Texas, and all of a sudden I got cancelled from the shipping order. My buddy, he left for the South Pacific, China Burma [India] Theater, a couple days later. And the captain or the sergeant said, “I don’t understand these cancellation orders. You’re healthy; everyone goes overseas if they’re healthy.”

So notwithstanding that, a couple days later, some orders come through, and the sergeant said, “I’ve never seen orders like these. You’re supposed to go from here, take all your papers with you, no dependents, and go to Knoxville, Tennessee, and call this telephone number. And when you get to there, you’ll find out where to go from there, I guess,” which I did of course. I was in the Army. 

And at the railroad station, the Army picked me up in a car. There were two other men also from Texas in the same shipment. I don’t remember their names. And we came out to Oak Ridge, which was brand new. The sergeant, by the way, said, “There’s no Army camp near Knoxville either, so I don’t understand this!”

In any case, the next morning we got the security interview by a lieutenant. And the lieutenant, paraphrasing only a little bit, said, “What you do here, what you see here, will stay here, or you’ll be shot here.” And that was standing a little bit of an exaggeration there. We understood we were in a very serious security operation for the government. And they said, “You’ll be assigned somewhere here, probably on this project.” And that was my introduction to Oak Ridge. 

How soon was it before you started actually going to work?

Kupp: Okay, well then, that same day we filled out the security questionnaires, of course, for the FBI clearance. And, of course, I heard later from my parents, who were in Detroit, Michigan, how all my neighbors were saying, “What’s the matter with Robert? The FBI’s been calling here, wondering, ‘What’s his problem? What’s his problem?’” And they didn’t know either, of course.

But, eventually, it was only three weeks later that the secret security clearance came through. It was much faster in those days. I had an interesting experience at that time, though, while I was waiting for clearance. Again, the Army looked at my record and said, “Oh, you’re a medic, huh? Instead of building boardwalks, we’ll assign you to the hospital.” So, for the next three weeks, I worked in the hospital. And that was an interesting experience, which I discuss a little more detail on in my book [A Nuclear Engineer in the Twentieth Century].

Then, three weeks later, I was interviewed at K-25, and apparently I passed the interview, so I was accepted to be a supervisor in what was called the Line Recorder Department. It was a mass spectrometer that determined the concentration of various materials in the cascade while it was being processed.

What did you do on a daily basis, or on an hourly basis?

Kupp: You mean, well, at the plant, you mean?

Yes, at the plant.

Kupp: Well, the plant, as you well know, is a mile long, and is divided into multiple buildings. Well, when I got there, which was basically January 1945, it was just being started up. They started the plant by sections, and in these various sections of the plant, in the middle of each building of the plant, there were multiple buildings, each roughly 300, 400 feet long, and about maybe 100-200 feet wide. 

There was a—called a line recorder station. And this station was an area which was enclosed in a, just sort of, rail fence, not a barrier fence at all, just a divider fence, and there was some equipment in it. And it had four mass spectrometers in this station, and it was operated by an individual operator in that station.

And, as a supervisor in that department, I would be in charge of the operators running in several of these buildings, maybe four or five buildings, or four or five of these line recorder stations. And this line recorder itself was a unique development.

As I said, it was a mass spectrometer, and, prior to this time, the only mass spectrometers that were used by anyone were used in universities by knowledgeable professors or very scientific-type people. And, in this particular case, the mass spectrometer, and its readout, and the maintenance of it, and the valving to get the samples to it, had to be done by a local Tennessee operator, who probably had a high school education. And, as such, it had to be relatively simple.

And there were minor hazards involved in one of these stations. A mass spectrometer requires a very, very high vacuum in it. And to make that vacuum, you use something called a mercury diffusion pump. And for the mercury diffusion pump, you need a very cold source to condense the gases and mercury coming out of it, and for that you use a mixture of dry ice, powdered; liquid nitrogen; and something like—no, the liquid nitrogen was not in that—but dry ice and trichloroethylene. It’s a minor toxic solvent, toxic if you drink it, not in the form that’s there, so that you had to be careful with it.

In addition to that, these stations were also used for sampling of the uranium-235, UF6, that was in the cascade. And in the sampling process, you had to dip a small sample tube, a steel, stainless, a nickel tube, which had a valve on top of it, and valve it in, and then you put the bottom of this tube in liquid nitrogen, which is—I’ve forgotten the temperature, but minus umpteen a hundred-something degrees Fahrenheit, minus. And you had to be very careful with that because it would freeze anything solid as a rock. If you put a banana in it and threw the banana on the floor, it would shatter like glass. So it was very cold.  

My job was then to see what problems existed in each of these stations, if the operators had problems. The line recorder itself, the output from it, scanned a whole series of different possible chemicals or gases that would be in the cascade.

And they were printed out on a strip chart, a printed chart, which showed the concentration of that particular item, particular gas. That printout was also duplicated for that particular station in the central control room of the plant, which I subsequently worked in.

So this was my first experience there. Of course, on all sides of us, both above and below the plant, construction was still going on, so there were wire barriers where the construction was going on, and where the operations were going on. 

Must have been difficult conditions to work under.

Kupp: They weren’t difficult because most of the construction was—well, you’d have the fences, and the building you were in was perfectly clean and operable, and you didn’t have to go to the lower floors. 

By the way, this line recorder station was on the top floor of the plant, the fourth floor. All of that process equipment, of course, the barriers and the pumps and everything, were on the second floor of the plant, well below us. And that’s where most of the construction was going on.

Were there ever any emergencies in the plant while you were there? Do you recall?

Kupp: Yes. Yes there was, in fact. One that I remember—it was sometime in 1945, but I can’t remember the date. I don’t know whether it was before or after the bomb was dropped, in fact.

I came on—this work was shift work, of course—and I came on the four to twelve shift, the afternoon swing shift. This was when I was later in the central control room. And I came in the central control room and looked at this array of fifty line recorder stations and the other instrumentation that’s there and said, “What has happened?!”

Apparently, about an hour or thereabouts before—I’m not sure of that timing—there was an absolute, complete, total power failure in the plant. I understand the circumstances was that Alcoa [Aluminum Company of America], who was on the TVA system and uses a huge amount of electricity in their aluminum processing, had been hit by lightning—there was lightning storms going through at the time—and they dropped their whole electrical load.

And that surge went through the whole system, including to the Oak Ridge Power Plant. And Oak Ridge Power Plant tried to pick up the extra load. And, in the electrical circuitry and switching, some of the switches, some of the breakers got overloaded, and they kicked out.

There was supposed to be a sequential failure mode, where the least critical goes out, you know, the local lighting, and then the process equipment, then instrumentation equipment, and finally the emergency lighting and equipment. And apparently, as I understand it—I wasn’t in the plant at the time—everything was black, absolutely black; no lights, emergency or whatever.

Well, they got some of the lights on fairly soon, and then some of the others, but it took a long time to. And all of the individual buildings in the plant were then isolated, so that you didn’t screw up the process, foul up the process. And it took a while then after that to get the plant running because when you try—you have to start up the plant in series, and there were only so many people who were capable of starting up the plant, so you had to go through the plant in a sequence.

In addition to that, one of the issues is, the seals of the blowers, on starting up, have a certain percentage probability of failure because, when they’re running, they’re in a different condition than when they’re starting up. They rub each other when they’re starting up, the seals do, but when they are running, they don’t touch each other. And, as such, whenever you start up a plant or a section of the plant, you will maybe get some failure, if there’s the least bit of particle of dust in these seals. So that created quite a problem for about a month or so.

For a whole month?

Kupp: Yes. I mean, part of the plant was running fairly immediately, but, you know, the overall effect was quite a while. That was the only major emergency that I know of there. No terrorist attacks or anything like that! 

That’s a good thing! So if you were going to preserve one artifact or maybe a memory from K-25, what would you think would be important to preserve? 

Kupp: Well, you know, I’ve been listening the last couple days to the discussion of the top of the plant at the bottom of the “U”—not the top of the plant, but the bottom—the “U” section of the plant, the north end of the plant, where the three buildings there were going to be preserved or proposed to be preserved. That’s a good idea.

By the way, right at the corner of that “U” was the plant’s central control room. And that was an impressive array at the time. With the automated controls and control rooms that are capable of being built today, it wasn’t too great by comparison. But, at the time, this half-circle of array of instruments were quite impressive, and the desks there, and the other instrumentation and so forth, would be nice to see. 

The fact that the line recorder stations and that type of instrumentation was the first of its kind—actually, there would have been a line recorder station in these three buildings also, so that should be part of the preservation, certainly. 

I was pleased to hear yesterday that, on the second floor of the plant where all the blowers exist, the Allis Chalmers blowers, that they plan to have at least one of the cells with either a glass front or an open front so that you could see the piping and the outside of the barrier vessels, so that you could see what was happening there.

Was it noisy when you worked there, at the plant? What was the sound like?

Kupp: Well, you know, we were quite a ways away from the motors. If you ever went down to the motor bay, it was noisy. On the fourth floor, though, it was not particularly noisy, you know, not nearly as noisy as many places I’ve been in or worked in before.

As I recall, the central control room had a little bit of air conditioning, as opposed to the—I’m not positive of that, but I don’t recall being uncomfortable in the central control room. The rest of the plant, of course, only had ventilation on the fourth floor.

It was an exciting time. In addition to my work in the central control room, actually, I worked at the very top of the cascade, just above where they took out the product, and helped start up that particular section. It was a somewhat different tech—same basic philosophy or technology, but altogether different kinds of equipment up there at the very top.

They didn’t have blowers; they had a different kind of compressor, and so forth. So I helped start up that particular section of the plant for, again, the line recorder department. And they had a different kind of instrument to measure the materials up there than was in the rest of the plant. 

From the central control room, I was also vacation relief in the air plant, which produced the dry air that was in these cells where all the equipment was, where the barriers were. They were steel cells, steel walls. And in that steel—in the enclosure was absolutely dry air, one hundred percent dry, not just dehumidified, dry. And this air plant dried that air. In addition to that, I worked in the compressor plant and also in the cooling water plant as vacation relief. 

So I had a good perspective of the whole operation, or much of the operation. And, of course, at the top of the plant, in the line recorder station at the top of the plant was where the product was removed, the final product from K-25, the enriched uranium-235. Our operators were responsible for that operation also.

When did you figure out what project you were working on, that you were actually working on producing uranium-235?

Kupp: In my book, I describe that. It is interesting that another GI and myself in the SED [Special Engineer Detachment], we had Pollard and Davidson’s book, Particles of Modern Physics, I think was the name of it—I’m not sure of the name, but Pollard and Davidson were the authors.  It was published in 1941. And, of course, fission was discovered in 1938 in Germany, and, you know, all subsequent developments and so forth.

Well, Pollard, in this book, about in a page and a half, two pages, described a situation where, summarizing it in a short paragraph, he basically said, “If you sometimes hear of an explosion that is inconceivably large, much larger than you could possibly conceive of from any chemical explosion, you can assume that someone has separated the isotopes of uranium and produced a high concentration of uranium-235, which they have assembled quickly into a chain reaction. And this chain reaction, being so rapid, would cause an incredibly large explosion.”

And that was published in 1941. It was taken out of print, of course, but there were a few copies around at that time. And so, being in the line recorder department and knowing the technology of what we were doing, even though it wasn’t uranium hexafluoride that was running around in the plant, it was Tuballoy [refined natural uranium] hexafluoride, TF6.

And there weren’t many materials that had a molecular weight of uranium, of 235 and 238. You could look up in a Mendeleev chart and find that 235 and 238 were uranium. Now, knowing we’re separating uranium-235 and 238, and with this two pages of the book, it was obvious we were making the material for an atom bomb. 

Now, I didn’t know anything about—I knew zero about Hanford, never heard of it. Although, I had picked up a rumor someplace or other, and I have no idea where, that there was a site somewhere in southwestern United States that was doing something on the project. But that’s all I knew of the rest of the project.

I knew there was a Y-12 section but I didn’t know quite what they did there. I mean, I knew they were doing something there related to the project, but I didn’t know it was a calutron, or what should be called a super, super mass spectrometer, because that’s basically what it is.

Dr. [Alfred] Nier, by the way, of University of Minnesota, I think, was the brains behind much of the mass spectrometer development on the project, from the helium detector, which was the simplest of the mass spectrometers, used to make the whole plant leak-tight, to the line recorder, which I’ve described already, to the more deluxe mass spectrometer that was used to measure the concentrations of uranium-235, 238, which are much more difficult to measure because they’re close together, and then finally to the calutrons in Y-12. I didn’t know much about what was happening at X-10 either. I knew there was an X-10 area, that’s all. 

The GIs, the SED, were generally kept together. Like the dormitory I was in were all K-25 kind of people. The man I shared the room with, Fred Hargess, he was in the instrument department in K-25.

And where was your dormitory? Where did you actually live?

Kupp: It was out in the western part of the Oak Ridge. Jefferson Area, I think it was called.

And how did you get to the plant every day?

Kupp: Bus. 


Kupp: Bus, of course. Yes.


Kupp: Full, yes. [Laughter.] But it was easily manageable.

By the way, one of the things related to my early comment that—the story on my Officer Candidate School application. The sergeant said, “You take these to your next station and turn them in, and you go onto their officer candidates list, or quota, because you’ve been approved already.”

Well, on arriving in Oak Ridge and understanding that I was going to be a professional engineer, if you like, or do engineering work, I decided that that would be more productive than me becoming an officer in the medics, so I didn’t bother turning those papers in.

I think they can understand that.

[Tape Switch.]

Kupp: Okay. I put this thing together for this event in Oak Ridge, and it has a very little bit of the history, starting with when we first got here, of course, we only wore the service department star on our uniforms. But after the bomb was dropped, we got the atom bomb patch, which, of course, has a lightning going into the nucleus of something or other, probably uranium, and creating a mushroom cloud. Or that’s sort of the impression that it gives, in any case.

And then, at the time of the bombing, the whole Special Engineers Detachment were awarded the Meritorious Service Award, which was a certificate and an arm patch for your uniform. And, of course, when I first arrived here I was a private and, because of my diligent work certainly, I eventually became a sergeant, I guess. I don’t know why, maybe it just came routinely.

And, you know, when we were here there was tennis, which—I was on the Carbide tennis ladder, which was a good thing to do. There was swimming, there was horseback riding. And here’s a picture of me when I was in the dormitory.

Apparently I was a T/3 [Technician Third Grade] then. That was before—apparently I made some stripes after that too. And this is just a more recent picture so that they could see it was the same person, maybe. And then you had, of course, the emblems for the Corps of Engineers, which we were part of as a Special Engineers Detachment.

So how did the tennis ladder work?

Kupp: Well, a lot of corporations or companies or cities have them. Basically, if you’re interested in playing tennis, you list yourself, and you’re listed in order from one to—I think the Oak Ridge tennis—the Carbide tennis ladder had about twenty-five tennis players on it.

And what you were required to do is, once a week or thereabouts—I’m not sure of the timing—you were to challenge someone who was not more than two notches lower than you on the tennis ladder. So if you were fourteenth, you could challenge someone who was twelve, and if you beat them they became fourteen and you became twelve. So that the best tennis player in Oak Ridge, or in Carbide, was number one, and the lowest one on the ladder was number twenty-five.

I was about the middle of the ladder, ten, twelve kind of area. I remember once when we were—when that whole event was taking place, someone came on—you came on at twenty-five, of course, because they didn’t know whether you played or not. And one week later he was eighteen; a week later he was fourteen; a week later than that he was twelve, which was me. He beat me badly. [Laughter.] And he became number one on the ladder. I don’t even remember his name, but he was good! [Laughter.]

He stayed number one for a long time. [Laughter.]

Kupp: He stayed number one, I think, for a long time. But that’s the way the tennis ladder worked. 

What other sorts of things were there to do in town? What was social life like?

Kupp: Well, there was a, I guess, a couple movie theaters. And then, every once in a while, there would be a party, either at the PX, or sometimes a shift party. All of the people who worked at Carbide would get together at Jefferson Hall or one of the other places and have a dance and drinks and so forth. And it was crude but pleasant, exciting. You know, different, certainly, than you would expect in an Army camp or a new town. It was very exciting times.

And, of course, when the bomb was dropped in August of ‘45, 6th, the town went wild. It was absolutely crazy because, as was generally reported in the papers, very few of the people here knew that we were working on a bomb. And just about no one knew what the status was, because, you know, as relatively young engineers—well, we had to be young then to be here now—it was not possible for us to know how much material was needed for a weapon or anything else. We weren’t sophisticated physicists like Oppenheimer and the rest of them out in Los Alamos.

So when you found out that the bomb had been dropped, what was the reaction?

Kupp: I think most of the people who were in the United States at the time fully supported Truman and the philosophy of dropping the bomb. I mean, we had all been exposed, in the papers, to the Japanese defense of Iwo Jima and all of the other places that were killing thousands of U.S. soldiers, as well as tens of thousands of Japanese soldiers.

And it was clear that the Japanese military, to everyone who has studied it, and most of the history says, that they were all dedicated to fighting to the end. And it was a general conclusion of Truman, certainly, and most of the people in the United States, that the war was ended, and thousands, maybe hundreds of thousands, millions of lives were saved by dropping the bomb.

That’s nearly an oxymoron. And the second-guessers of the more recent—later generations have second-guessed it much more than the people who were there originally and saw the situation. And, in fact, just about everyone also concluded that two bombs would be necessary because the first one could have been a fluke, and how much more we could do was debatable.

And it was finally, I think, the Emperor himself who made the decision that, 

“Now we’ve got to go.” And he overrode—as I understand it, from my reading of the subject, that he vetoed the military even after the second bomb. So it was a very positive end to the war as far as, I think, everyone involved was concerned.

Now, I know that you have a story about being followed by the FBI.

Kupp: That was a funny experience! Yes. I think my only furlough from Oak Ridge while I was working on the project, before the bomb was dropped, I went back to Detroit, my hometown.

And in Detroit, we—my future wife and I—went on a date with a Marine sergeant that we knew in college and his date, who also became his future wife. And we went to the Statler Hotel in downtown Detroit for dinner.

And we had a nice dinner, you know, nice conversation. And we talked very broadly about what we were doing: “Well, I’m in Oak Ridge doing some military training,” and miscellaneous nonsense like that. And it was very strange, by the way, for anyone you talked to in Detroit, or anyplace else for that matter, being in the Army, as to, “What are you doing?” And you had to talk around the subject because obviously you couldn’t talk about the subject!

In any case, what—leading to is, we came back, I came back to Oak Ridge, of course, and Don went back to his Marine barracks. And one time some time later—and I didn’t hear this until after the war when we got together again—Don was in charge of quarters one night, as a sergeant, and so he was in the company headquarters.

And, being somewhat inquisitive, he went to the files, which happened to be open. I guess they didn’t have the security that we had on the site here, so they weren’t locked at night with combinations and so forth. And he went to his security—went to his folder of his career and he pulled it out, and he found there a note saying, “Don Healis and Robert William Kupp”, with my Army serial number, “With their dates went to dinner at the Statler Hotel.” And I don’t know whether they said, “As far as we can tell, nothing classified was discussed.” I don’t think they even said that.

But it was a note saying that we had been to dinner there together. And obviously he or I were followed. I sort of expect it was him, because he was in a very secret radar development project, which was equally as secure as me. I think he was probably more directly involved with critical materials than I was, although we never were able to find out who was being followed.

Do you have any other questions?

Kupp: I might add as a final story the—after my military career here, I came back to the same job in the central control room as a civilian. I did that, one, to get it on my civilian record as being a genuine professional job, as opposed to being an assigned in the Army. I didn’t know how the industry would look at that in the future.

So I came back. I only stayed six months, though, because I was missing my chemical engineering degree by one semester. So I went back to school and got my chemical engineering degree.

And then, rather than come back to—at Carbide, I didn’t get a leave of absence because I was only there six months. But they said I could come back to the same job after graduation.

Well, I looked around and I hired then with the Kellex Corporation, who built K-25. And they were going to be building the materials testing reactor at X-10 at that time. This is now August ’47. And so I hired with them as a process engineer, a process design engineer, and back to Oak Ridge, though I came to build the materials testing reactor.

Well, at the end of ’47, the Army decided that they would build this reactor in Idaho. They were going to open up a new site in Idaho, Idaho Falls. And so they were going to cancel the project in Oak Ridge here. Well, Kellex then, fortunately, were not out of a job; they were out of that job, but they were assigned to build the three nuclear fuel reprocessing plants in Hanford, Washington.

And that was going to be designed, though, built out of New York—designed out of New York. So back to New York—well, not back to New York because I had never been to New York before. So I went to New York and lived there. And we built the—designed the three reprocessing plants in Hanford, Washington: redox, PUREX, and waste-metal recovery.

I spent six months out in Hanford, Washington on that project then. Subsequent to that, Kellex Corporation was then bought by a company called Vitro. And they became Vitro Engineering Company. And with this background there and so forth, I became Vitro’s chief nuclear engineer. I stayed with them a number of years and we formed a separate company later.

And so my full career was in the nuclear engineering after that, and, more recently, in nuclear safety, safety analysis, all with a flavor of process engineering and so forth. Vitro built Indian Point 1, one of the three additional power plants in the United States, and that’s when I was chief nuclear engineer there.

My experience here in Oak Ridge was a birth of a chemical engineer becoming a nuclear engineer. And I subsequently taught nuclear engineering at New York Polytechnic Institute, part-time, and did a lot of consulting for the government, eventually, in the Department of Energy, and in safety review committees both in Hanford and in Savannah River. So it was an incredibly exciting career which started here in Oak Ridge.

Copyright 2014 The Atomic Heritage Foundation. This transcript may not be quoted, reproduced, or redistributed in whole or in part by any means except with the written permission of the Atomic Heritage Foundation.