The Manhattan Project

Alvin M. Weinberg's Interview

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Alvin Weinberg was an American nuclear physicist who was in charge of the multiplication factor estimates for reactors in the Manhattan Project. He served as an assistant to Eugene Wigner, with whom he began to work at the University of Chicago in 1941, while taking frequent trips to Oak Ridge. Along with Wigner’s team, Weinberg assisted in designing reactors. He also contributed to the development of peaceful applications of nuclear power. Weinberg discusses Wigner’s rush to create the reactor due to the threat of a German atomic bomb, highlighting both the conflict and cooperation with DuPont.
Manhattan Project Location(s): 
Date of Interview: 
1986
Location of the Interview: 
Chapel Hill
Collections: 
Transcript: 

[At top is the edited version of the interview published by S. L. Sanger in Working on the Bomb: An Oral History of WWII Hanford, Portland State University, 1995.

For the full transcript that matches the audio of the interview, please scroll down.]

Book version:

I was working in mathematical biophysics at the University of Chicago. One of my professors asked me to help him out for six months at half-time on the uranium project which he had got involved in, and I began in 1941. We both were rather skeptical it would amount to very much. He asked me because it turned out there was quite a bit of analogy between the mathematics used in calculating how nuclear reactors would work and how cells work. So, with my biophysics background, I had a little bit of a head start.

Eugene Wigner came to Chicago as head of the theoretical group and I became one of his assistants. The job he gave me was to estimate and keep track of the value of the neutron multiplication factor in the reactors. You must realize since we were trying to make a chain reaction with natural ura­nium and graphite that it was a very close thing whether it would work at all. It wasn't until May, 1942, that the experiments were sufficiently successful to demonstrate quite clearly you could make a chain reaction.

It was simply this. If everything absolutely went in the very best possible way, then the multiplication factor that we calculated was about 1.08. But things would never be that good. There would be impurities, which captured neutrons, and you would have to put coolant in and have cladding on the fuel elements and so on, all of which absorbed neutrons, and the multiplication constant might turn out to be 1.01. If it were only 1.01 the reactors would have to be miles big, the bigger the multiplication the smaller the reactor. In a bomb, the multiplication is around 2.0 and so the bomb is small. The bomb, of course, had a high multiplication factor because it was made of almost pure U-235 (or Pu-239). In a reactor, we were working with natural uranium, of which fissionable U-235 is only 1/140 of the whole.

But Wigner was very confident it would work. He played the absolutely central role in the Hanford reactors. He was really the inventor of the Hanford reactors. The original direction was to use helium as the coolant. Wigner objected because he said the materials problem would be difficult to solve in a short time. The helium-cooled reactor was a very high temperature device and he said you should shift to a lower-temperature reactor and cool it with water and clad the uranium with aluminum. By the spring of 1942, long before the first chain reaction was demonstrated, he had begun design studies on a plant with water cooling. I was doing the estimates of the multiplication factor, the theoretical work, and Herb Anderson, among others, was involved in the experiments.

Wigner convinced Arthur Compton it was a good idea to pursue water cooling seriously and it became more and more important. When the Du Pont Company was brought in, later in 1942, they made a study of the differ­ent possibilities of helium and water and decided Wigner was right.

Wigner and I decided what the lattice spacing would be. I remember clearly doing the calculations and going into his office one day and we looked at the numbers, and we said, "Well, should we make it this or that? Let's make it more like that." The lattice spacing was 83/8 inches, that was close to the optimum and happened to be the size the graphite blocks came in. We did all the details, how the slugs would look, how they would fit in the tubes, every single one of these details was essentially controlled by Wigner, and some very able people helped him.

The Hanford design culminated in a report, called process design for a water-cooled plant, and the number was CE-407, January, 1943. It was prob­ably the second-most important report of the Manhattan Project, the first being the report on the first chain reaction. The remarkable thing was that Wigner had the nerve to design a big reactor, and had the design essentially complete before the first chain reaction was established. In fact, Wigner would sometimes say, he wasn't quite serious about it, that he was so confident the chain reaction would work that he wouldn't attend the first one. But he did, and he broke out the bottle of Chianti to celebrate.

The unique thing about Wigner was that he was the only one on the project, and in this he actually exceeded Fermi, who had such a complete understanding and interest both in the physics and the engineering. Fermi was mostly interested in the physics but if need be would get involved in engineering. It was Wigner who did both. In any design, you have to make compromises, you have to be very confident of your knowledge.

Du Pont, with Crawford Greenewalt as contact man, took Wigner's preliminary process design and made it into the actual engineered device. It was very close to Wigner's design. The Du Pont blueprints were sent back to Chicago and examined in detail by Wigner. One of the foremost theoretical physicists in the world during the war did the most detailed kind of engineer­ing. It was that sense of responsibility he had that was so extraordinary and important.

The Du Ponts also did something which was relatively important. The question was how big to make the reactor. We said 1,500 fuel tubes was okay, which meant the reactor was like a big cylinder with a circular cross-section. But it was built with corners and the Du Pont engineers, who were rather conservative, said, "Let's fill in the corners with fuel tubes." We didn't make a big fuss, so they made the actual reactor with 2,004 tubes, which turned out to be really quite helpful because of the xenon poisoning, which occurred with the first reactor at Hanford. We didn't think the poisoning would happen, although John Wheeler had looked at all the fission product possibilities. It was theoretically possible, but it was a sheer fluke it turned out to be xenon, which decays with a rather short half-life, so it didn't screw up the whole project.

Wigner likes to say I designed by myself the X-10 reactor at Oak Ridge in early 1943, but it really wasn't much of a thing. There really wasn't much design that had to be done there. I was responsible for deciding what the lattice spacing was (the geometry of the nuclear pile). You see, the multiplication constant depends on what that lattice spacing is. That really was what he meant by design.

The X-10 at Oak Ridge was simpler than Hanford because X-10 was air cooled. The question of the multiplication was much less sensitive. Wigner objected to the X-10's air cooling because he said it wouldn't be an adequate prototype for the Hanford reactors because Hanford's were to be water cooled.

The significance of the X-10 to Hanford was that nobody had ever extracted plutonium on a large scale, separation had always been done on a micro-scale. This was the first time in human history that mankind was han­dling radioactivity on this enormous scale. That was what Oak Ridge was set up for, to see if this whole thing would work when you had this intense radio-activity. X-10 was the first reactor that produced significant amounts of heat, a thousand kilowatts. Secondly, it was the first reactor in which sizeable amounts, meaning gram quantities, of plutonium were produced, about one gram a day. The Hanford reactors each one initially produced about 250 grams a day.

Side by side with the X-10 was an elaborate chemical plant quite a bit like the Hanford chemical plant. It was more like the Hanford chemical plant than the X-10 was like the Hanford reactors. Clinton Labs (Oak Ridge) was mainly set up to practice extracting plutonium. Du Pont people destined to go to Hanford stopped in Oak Ridge for several months or as long as a year, learning the chemical plant and practicing on the reactor.

There was always a bit of tension between Wigner's group and the Du Pont people. Wigner at the time thought Du Pont wasn't moving fast enough. He was wrong on that. He was wrong to think the scientists could build the reactors themselves. Wigner threatened to leave the project. On one occasion, he was like Achilles, sulking in his tent. But when he sulked in his tent, that didn't mean he wasn't working. He stayed home and worked three times as hard.

You see, Wigner and his friend Leo Szilard really had more or less first-hand contact with the Nazis. They lived in mortal terror of them. One interesting sidelight is that at Christmas time, 1943, Arthur Compton asked Fermi, Wigner and myself to come to his office. What we were supposed to do was estimate when we thought the Germans might have an atomic bomb. This estimate would be passed on to James Conant, who was in the White House as a presidential adviser. Wigner always hedged his estimates in the most pessimistic way. If it turned out better he would feel good. Wigner wrote on the blackboard it would take the Germans two months to build a reactor, three months to take the plutonium out, two months to make the bomb, by Christmas of 1944, they would have the bomb. That scared us shitless, I guess you would say.

Szilard was always sort of the gadfly. He was always marvelously imagi­native. He really didn't have the scientific power that Wigner had. Szilard had a certain kind of genius in that he was extraordinarily imaginative and original. Wigner had that, but he also had enormous scientific power. I mean by this, that any problem that was solvable, Wigner could solve. Szilard didn't have that capacity. Wigner is not known well by the public because he is rather retiring. Among physicists he is known totally. Fortune magazine described Wigner as the quiet genius who singlehandedly invented much of modern physics. So much of modern physics' structure and so on goes back to Wigner. His role in the Manhattan Project is not fully appreciated and the entirely central role he played. You would not have had Hanford on the time schedule you did had it not been for Wigner.

When it comes to my own ideas on nuclear weapons, I wrote a paper which appeared in the Bulletin of the Atomic Scientists (Dec., 1985) about what I called "the sanctification of Hiroshima." What I said, although I signed the Franck Petition suggesting that a demonstration be made of the bomb in an uninhabited area, was that I never have been concerned about dropping the bomb because I tended and still tend to believe that on balance you probably saved lives by dropping the bomb. The point of my article was that the 40th anniversary of Hiroshima was almost what one could describe as a reli­gious outpouring of concern over the Hiroshima incident. It seemed to me the bomb at Hiroshima was beginning to acquire a kind of transcendent significance which can almost be described as having semi-religious overtones. I think that is a very important, very proper and desirable development. We're going to live with nuclear weapons forever, or the next 50 years, 100 years, 1,000 years.

The significance of Hiroshima is being made somehow part of the myth of mankind, in somewhat the same sense that the Holocaust is becoming a myth among Jews today or the crucifixion, if you like. I said I did not believe a test of the bomb could ever be made into a religious myth. Only because 100,000 people or more were killed can that event be mythologized, or canonized.

I don't think the second bomb, the Nagasaki bomb, was necessary. No, that was strictly General Groves. In fact, I was drinking whiskey with Groves one night in a hotel bar in New York after the war and he more or less agreed the second bomb was not needed. He didn't say why. Groves was first of all a military man.

 

Full Transcript:

S.L. Sanger: This is an interview with Alvin Weinberg on March 15, 1986 at his room at the Europa Hotel, Chapel Hill, North Carolina. 

Anyway, why don’t you just tell me about how you got into the [interruption]?

Alvin M. Weinberg: Well, you see, I was working in mathematical biophysics at the University of Chicago in 1940. And one of my professors there, Carl Eckart, asked me to help him out six months half-time on the uranium project, which he had gotten involved in. And we were both rather skeptical that it would amount to very much, and so I said sure, I would help out. The reason he asked me was because it turned out that there was quite a bit of analogy between the mathematics that was used and calculating how nuclear reactors would work and how cells would work. So I had a little bit of a head start in this respect.

Eckart then left shortly after Pearl Harbor. Eugene Wigner came to Chicago as the head of the Theoretical Group and put all the work together at Chicago, as you may remember, and I became one of Wigner’s assistants. The job that he had me take charge of was to estimate and keep track of the value of the multiplication factor in the reactors. You must realize that since we were trying to make a chain reaction with natural uranium and graphite, it was a very close thing whether it would work at all. And it was not until May of 1942 that the experiment was sufficiently successful to demonstrate quite clearly that it could make a chain reaction.

Sanger: Is that why you were skeptical originally, that you did not think it would work?

Weinberg: That is right. Well, it was simply this. That if everything absolutely went in the very, very best possible way, then the multiplication factor that we calculated was about 1.08. But things would never be that good because there would be impurities and you would have to put coolant and you would have to put cladding on the fuel elements and so on. And so the multiplication constant might turn out to be only 1.01 and if it were only 1.01, then the reactor would have to be miles big. The bigger the multiplication, the smaller the reactor. In a bomb, the multiplication is around 2 and so the bomb is just about like this—it is very small. The bomb, of course, had a high multiplication factor because it is made of pure U-235. This was only one part in 140 of those, U-235.

But Wigner was very confident of it and he played the absolutely central role in the Hanford reactors. I do not know if you were aware of that.

Sanger: Yeah, I spoke with—

Weinberg: He was really the inventor of the Hanford reactor. And the original direction of the project was use helium as the coolant, but Wigner objected to that because he said that the materials problem would be too difficult to solve in a short time. Because that was a very high temperature kind of device, and he instead said you should cool it with water and clad the uranium with aluminum. And by spring of 1942—this was before the first chain reaction, you understand, that had been demonstrated. He had already begun design studies on a plant with water cooling, as it was called, and I did the estimates of the multiplication factor for that system.

Sanger: For the water-cooled design.

Weinberg: Well, for all of the reactors. I was sort of in charge of the multiplication factor for the Project so whatever they were working on, I would make those estimates. And Herb Anderson, of course, was involved in doing the experiments but I was doing theoretical work. 

Well, then Wigner convinced Arthur Compton that it was a good idea to pursue this seriously and within the Project, the gas cooled reactor was continued but rather at a low level and so water cooling gradually became more and more important. And then when the DuPont Company was brought in—I think they were brought in, I have forgotten now exactly—it was about September of 1942. I think that was about the date. They made a study of different possibilities and DuPont decided that Wigner was right, that it should be a plant with water cooling

Now in the meantime, Wigner and his little group, which consisted of Gale Young, who was sort of his engineering assistant, who is still alive and lives in Oak Ridge.

Sanger: Oh, he does? I did not know that.

Weinberg: Yeah. He was Wigner’s engineering assistant. I was his sort of multiplication constant assistant. There was a fellow from Belgium by the name of Wasserbaum who worked with us, he was an engineer. There was an engineer, Miles Leverett, who is still alive. Very  prominent engineer. He was in charge of all the work on reactor safety, General Electric.

Sanger: But on this, he was involved in the design of the mechanism.

Weinberg: Yes, that is right. And then there was another engineering assistant of Wigner’s. Young was more than an engineering assistant. He was really Wigner’s primary assistant. I was sort of a secondary assistant. And then there was a fellow, Lee Ohlinger, who eventually went to the Northrop Company. And Ohlinger was the fellow who actually drew the pictures and did some of the design of the details of the Hanford reactors.

Sanger: How do you spell his name?

Weinberg: O-H-L-I-N-G-E-R.

Sanger: Is he still alive?

Weinberg: I do not know. I lost track of him. He was about five or six years older than I, so he must be about 76 or 77 years old now.

Sanger: How old are you?

Weinberg: I am going to be 71 in April.

Sanger: I spoke to Professor Wigner on the telephone some time ago and he said that he gave you the credit for almost designing singlehandedly the X-10.

Weinberg: Well, he likes to say that but that really was not much of a thing. I mean, there was not very much to design, that had to be done there. I was responsible for deciding what the lattice spacing was because the multiplication constant depends on what that lattice spacing is. And that really was what he meant by it, the design. But the engineering details were worked out by others. Henry Newsom, for example, a fellow who is on it, his lecture was given—was very much involved in designing the X-10 reactor.

Sanger: Was it simpler because it was air cooled?

Weinberg: Yes, much simpler. So the question of the multiplication was much less sensitive.

Sanger: It was totally air, it was not cooled by anything else.

Weinberg: Yes, yes. Now Wigner rather objected to that because he said it would not be an adequate prototype for the Hanford reactors, because Hanford was water cooled and this was air cooled. But the DuPont Company said, well, the main purpose was to get enough plutonium so you can test out the chemical plant.

Sanger: Could you tell me just in general terms what the importance of that X-10 was to the Hanford Project?

Weinberg: Well, the main significance was that they had never extracted plutonium on a large scale. It had always been done on a micro scale. And there were all sorts of questions. This was the very first time in human history that mankind was handling radioactivity on this enormous scale. And really, that is what Oak Ridge was set up for, to see whether the whole thing would work when you had this intense radioactivity. And so the significance of X-10 was that it—well, it was the first reactor that produced significant amounts of heat and so you actually had a reactor that was producing 1,000 kilowatts actually. 

Secondly, it was the first reactor in which sizeable amounts—meaning gram quantities—of plutonium were produced. It produced about one gram of plutonium per day. The Hanford reactors, each one initially produced about 250 grams of plutonium per day, each reactor. 

So side by side with the X-10 reactor was this elaborate chemical plant, which was quite a bit like the Hanford chemical plant. It was more like the Hanford chemical plant than the X-10 reactor was like the Hanford reactors. 

Sanger: Is it still there, the chemical plant?

Weinberg: Oh yes, oh yes.

Sanger: Because I visited the reactor once but I do not recall the—

Weinberg: Well, that big oblong building that is right next to that was the whole—

Sanger: That is not open, I guess.

Weinberg: No, it is not open. It is still used as a pilot plant.

Sanger: Oh yeah?

Weinberg: Yeah. 

Sanger: Do you remember how many cells it had in it?

Weinberg: Oh, about five, I think, yeah.

Sanger: But it was fairly sizeable.

Weinberg: Oh yes, it was a big installation but nowhere near as big as the Hanford installation.

Sanger: Yeah. Go ahead.

Weinberg: Well, so at Clinton Labs, that is mainly what the laboratory was set up for, to practice “how do you extract the plutonium.” That involved dissolving uranium, doing precipitation, and so-called bismuth phosphate method of extracting the plutonium.

Sanger: Did people come to Oak Ridge then? They passed through there sort of on their way to Hanford, I guess.

Weinberg: Well, there were two groups. There were the people who came down from the University of Chicago. It was kind of amusing because the DuPont Company was a subcontractor to the University of Chicago. The University of Chicago ran the laboratory and DuPont was a subcontractor and they managed the laboratory in the sense of did the engineering. And then there were any number of DuPont people who were destined to go to Hanford. It was the first stop then Oak Ridge for several months, though, perhaps as much as a year learning how to do the chemical plant and also, practicing on the reactor. Because that was the only reactor that was in the system, large reactor.

Sanger: And were you at Oak Ridge for quite some time during that period?

Weinberg: No, no, no, no. During the war, I was at Chicago but I would visit Oak Ridge regularly. Mmy first visit to Oak Ridge was in 1943.

Sanger: So you began with the Project when, did you say?

Weinberg: In 1941.

Sanger: And you were actually a PhD at Chicago then?

Weinberg: Yeah, I was in mathematical biophysics.

Sanger: Okay.

Weinberg: Well, then to get back to the Hanford story, so in something like three months between September and January of 1943, Wigner and his little group worked at feverish pace. You would not believe. Well, we would work every single day, including Sundays, actually working out the detail design on the Hanford reactor. And when I say “detailed design,” I really mean that. We thought of how the connections would go, bringing the water in, and how to remove the radiated slugs, whether to be vertical or horizontal or what the size reactor was. 

And actually, it was Wigner and I who decided what the lattice space in the Hanford reactors were. And I remember it clearly. I did the calculations and then I went into his office one day and we looked at the numbers and we said, “Well, should we make it like this or maybe like that?” And we said, “Well, we will make it like that.” It was eight and three-eighths inches was the lattice pitch because that was close to the optimum, and that happened to be the size that the graphite blocks came in.

All of the details—how the slugs would look, how they would be put into tubes—every single one of those details were essentially controlled by Wigner. But there were some very able people who, of course, helped them. And one of them who is not generally mentioned very much is Ed Creutz. I do not know if Wigner mentioned him to you. He was a physicist who became a metallurgist during the war and he eventually became the Acting Director of the National Science Foundation.

Sanger: Is that E-C-R?

Weinberg: E-U-T-Z.

Sanger: Yeah, I think I have heard his name. He was a metallurgist?

Weinberg: Well, he was a physicist who, because they needed metallurgists, he learned metallurgy of uranium and he did a great deal in the metallurgy of uranium. He is a remarkable guy. He became head of the Physics Department at Carnegie and then he went to General Atomics and was the head of their laboratory. Then he went to the National Science Foundation and became the active Director of the National Science Foundation. And after he retired, he was always interested in Polynesia so he became the curator of the Bishop Museum in Hawaii.

Sanger: Oh, he did?

Weinberg: Yeah, he still lives in Hawaii. No, I guess he moved back to the mainland.

Sanger: Oh, I did not know that.

Weinberg: Yeah. He would be a good one to get a hold of.

Sanger: Where might he be?

Weinberg: I do not know his present address but the way you would find that out is in the directory of the American Physical Society. Just call them up and they would get—

Sanger: Where are they located?

Weinberg: In New York City. American Institute of Physics is the holding company. American Physical Society is the subsidiary. And he would be a good one to talk to because he was—although he was not quite part of the Wigner group, he interacted very strongly with us. Because whenever we made some judgment on how to make the slugs and so on, he was the metallurgist who said, “Well, let’s do it this way, let’s do it that way.” And the actual cooling arrangement of the slugs was proposed, as I recall, by Ed Creutz.

Sanger: Was there a great deal of water treatment involved?

Weinberg: Oh yes, yes. But we were not involved very much in that aspect of the plant. That, Dupont took it over. You might say that during those days when the design—well, then, the Hanford design culminated in this report. I think it was called “Process Design for a Water Cooled Plant of 500 Megawatts.” I think that was the name of the report. And the number was CE-407. And the date of that, I believe, was January 1943.

Sanger: The number? What do you mean? 

Weinberg: Pardon?

Sanger: What do you mean the number? 

Weinberg: Well, all the reports had numbers.

Sanger: Oh, that were sent to DuPont you mean?

Weinberg: Well, all the reports that were produced at the Chicago Metallurgical Lab were numbered so they can keep track of them and this number was CE-407, which I suppose was the second most important report of the Project, the first one being the report on the first chain reaction. And the remarkable thing, of course, was that Wigner had the nerve to design a 500 megawatt reactor and had the design essentially complete before the first chain reaction had been established.

Sanger: Well, that is what I was going to ask. That was remarkable.

Weinberg: Yeah. In fact, Wigner sometimes would say—he was not quite serious—but he was so confident that the chain reaction would work that he was not sure he would go to the first chain reaction but he did. And he is the one that broke out the bottle of Chianti.

Sanger: Now that could be done because he could make a reasonable assumption that such and such would happen.

Weinberg: Right. And you see, the unique thing about Wigner was that he was the only one on the Project and in this, he actually exceeded [Enrico] Fermi, who had such a complete understanding and interest both in the engineering and in the physics. Fermi was mostly interested in the physics although if need be, he would get involved with the engineering. But it was Wigner who did the engineering, as well as the physics. He was the only person who controlled both of these.

So you see, in any design, you have to make compromises—engineering compromises, physics compromise—and you have to be very confident of your knowledge in order to be willing to make those compromises. Sometimes I think well, you look at the whole shuttle thing and you somehow have a feeling that you do not quite have the giants of a magnitude of Wigner or Fermi today who have the entire thing completely under their intellectual control and who have this total sense of responsibility for everything.

Well, then what happened, of course, was Crawford Greenewalt, who later became the Chairman of the Board of DuPont, he was the head of what is called the TNX Division. Well, there was always a bit of tension between Wigner’s group and the DuPont people. And Wigner, at the time, always felt that DuPont was not moving fast enough. For a while, he changed his mind but the last time he commented on how he reverted to his old position. But Wigner was wrong on that.

Sanger: In the sense that he thought the scientists could build it themselves?

Weinberg: Yeah, he was quite wrong about that. 

Sanger: I have heard several stories about that. I had spoken to Norman Hilberry, who told me that Wigner threw a tantrum almost—

Weinberg: Oh yeah, sure.

Sanger: --at times. 

Weinberg: Yeah, yeah. Wigner would always threaten to leave the Project and several—well, there was one occasion when he acted like Achilles sulking in his tent, so to speak. 

Sanger: Why was he doing that, do you suppose?

Weinberg: Well, he felt that they were not moving fast enough. And when he sulked in his tent, that did not mean he did not work. I mean, he just stayed home and worked three times as hard.

Sanger: Is that, do you suppose, partly because he was so conscious of the German threat?

Weinberg: Yeah, yeah, sure. You see, he and his friend [Leo] Szilard really had more or less firsthand contact with the Nazis, and we lived in mortal terror. 

And in fact, one of the interesting sidelines, at Christmastime in 1943, Arthur Compton asked Fermi, Wigner, and Alvin Weinberg to come to his office. And what we were supposed to do then was to make some estimate, which was then passed onto James Conant, who was in the White House, when we thought the Germans might have an atomic bomb. And I do not know if Wigner told you this incident but well, Wigner always hedged his estimates in the most pessimistic way so that if it turned out better, then he would feel good. If it turns out bad, you know. And so Wigner put down on the board, well, it would take two months for them to build a reactor, three months to take the plutonium out, two months to make the bomb. By Christmas of 1944, they would have the bomb. And that, of course, scared us shitless, I guess you would say. But in retrospect, one realizes that he was leaning over terribly backward. 

But that was the intensity with which he worked on the matter and he conveyed then to—of course, everybody on the Project worked with that intensity.

Sanger: And that was mainly because of the German fear.

Weinberg: Yeah, yeah.

Sanger: Fear of the Germans. Do you remember what the estimate was of this group? Or was that it—Wigner’s estimate?

Weinberg: Yeah, that was the estimate. Now I do not know what finally happened with that estimate. I do not know if Compton really took it seriously, but that was the result of that little meeting that we had.

Well, then I was saying, so then what happened—getting back to Dupont—Crawford Greenewalt was the contact man. He was the head of what was called the TNX Division. He would oscillate between Wilmington and Oak Ridge—Wilmington and Chicago—and some of us would go to Wilmington, and I went to Wilmington either once or twice as I recall. And the DuPont people then took Wigner’s preliminary process design, which was in that report, CE-407, and then they made it into the actual engineering device, three of which were built at Hanford. There were three reactors, remember.

Sanger: Was it close to what his—?

Weinberg: Oh, very close, yeah. It was almost the same. And then the blueprints were sent back—the actual construction blueprints were sent back—they were sent back to Chicago. And the blueprints were examined in detail. Every single important blueprint was examined in detail by Eugene Wigner. One of the foremost theoretical physicists in the world [break in sound], the most detailed kind of engineering. It was that sense of responsibility that he had, which was so extraordinary and important. 

The DuPonts actually did do something, which was relatively important. The question was how big to make the reactor. We said, “Well, 1,500 tubes was okay.” Which meant that the reactor was a cylinder with a circular cross-section, which meant that there were corners.

And the DuPonts, who were rather conservative engineers, said, “Well, let’s fill in the corners.” 

And we said, “Well, we do not think it is necessary,” but we did not make a big fuss about it. And they made it so the actual reactor has 2,004 process tubes, as they call it.

Sanger: Which turned out to be—

Weinberg: It turned out to be really quite helpful, because you probably have heard this story about the xenon thing being discovered. 

Sanger: You did not have any idea, of course, that that would happen I guess.

Weinberg: No, although John Wheeler, whom you ought to talk to—

Sanger: Yeah, I talked to him, in fact, the other day.

Weinberg: Before the reactor was built, he looked at all of the fission products to see whether there might be any that would cause this kind of trouble. And it was theoretically possible that it was just a sheer fluke that it turned out that there was xenon, and that xenon decays with a rather short half-life, so it did not screw up the whole project.

Sanger: Yeah, most of the people I have talked to, I guess, view that as the main dramatic incident after they started

Weinberg: Well, that is right. And you know, I recently looked into the question of what would have happened to the project if it were only 1,500 tubes rather than 2,004. Well, it would not have been as big a catastrophe as one might think. See, the reactors were designed for 250 megawatts and if it were only 1,500 tubes, then you probably could not operate more than about 200 megawatts to produce the grade of plutonium. It would not mean that the project was dead but—

Sanger: I mean, would it have been possible to put enriched uranium in or not at that time?

Weinberg: Did not have enough enriched uranium.

Sanger: It would not have worked.

Weinberg: Well, we just did not have it.

Sanger: Would not have it.

Weinberg: Yeah, did not have it, yeah.

Sanger: I guess if you had that, you would have had enough for a bomb quicker, I suppose.

Weinberg: Well, the Hiroshima bomb, of course, was enriched uranium, yeah.

Sanger: Well, why don’t you go on then with—

Weinberg: Well, our contact with the Hanford project then was really quite peripheral after that.

Sanger: After you worked through the design.

Weinberg: Yeah, although we were informed, you know, what was going on there and Wigner used to go out to Hanford. I do not know how many times he went out during the war.

Sanger: Several, I guess. 

Weinberg: Yeah.

Sanger: He told me he did not remember too much about it, because he thought it was mostly out of politeness they invited him. 

Weinberg: Yeah.

Sanger: They were working. He designed it so it was not anything new to anybody.

Weinberg: Yeah, yeah. And the first time I was at Hanford, I think it was—oh, I guess it was 1946 or so. 

Sanger: So you were not there during the war?

Weinberg: No, no. 

Sanger: Let’s see. 

Weinberg: No, you understand that the DuPont people did all of the standard process design—sizing of the pumps and well, the de-mineralizers, because it had to be very pure water that you put in. We were involved a little bit in the question of the choice of the site.

Sanger: Oh, you were?

Weinberg: Well, we were not the ones who decided but we did, for a while, look at maps and try to see where was the best place. And the place we liked was Lake Superior.

Sanger: Oh, was it?

Weinberg: Yeah, because it was very cold, very clean water. 

Sanger: Where in Lake Superior?

Weinberg: Well, there were two places, one near Houghton, Michigan, which is in the upper peninsula of Michigan. I do not know whether that is out in Lake Michigan or Superior. I think it is on that little branch of Lake Superior. And the other was near Duluth.

Sanger: I have never heard that. But were they ever taken seriously?

Weinberg: Not really. We called it “Site S” for Superior. And then when DuPont came in, the DuPonts, of course, had a much more realistic impression of what it really took to do something that size. And we were amateur engineers, although Wigner, he never studied physics. The only thing he studied was chemical engineering.

Sanger: Well, that is what I thought, yeah.

Weinberg: Yeah. But he was more or less self-taught as a physicist and won the Nobel Prize in Physics.

Sanger: Was there plentiful electricity at these sites in Michigan?

Weinberg: We never really looked into that. But of course, the Hanford reactors did not require all that much electricity. It was unlike the fusion plant, which required huge amounts of electricity.

Sanger: I read, and there is a recent book that mentions that one of the reasons Hanford was chosen was because of the electricity, all the electricity there.

Weinberg: I do not think that was an important consideration because Hanford did not use all that much electricity.

Sanger: Yeah, well, they mentioned the helium, this person—I do not know if this is so—the helium cooling would have required more electricity. Is that true?

Weinberg: Yeah, somewhat more because it took more pumping power.

Sanger: Yeah, and I guess some of that, that was still a factor.

Weinberg: Not really. I think the main factor was the remoteness and lots of clear water and the Columbia River.

Sanger: And clean water.

Weinberg: Yeah, clean.

Sanger: That was pretty early.

Weinberg: Clean, cold water, yeah. The DuPont people put in an entire refrigeration plant, which never was used. I think General Groves may have had something to do with it. Because if they could lower the temperature of the water a little bit during the summer, then they could run the reactors at a higher power and get more plutonium. But they never did use the refrigeration plant, but it was a huge refrigeration plant.

Sanger: Yeah, I think that has been mentioned.

Weinberg: Yeah, and I am not sure they built that into all three of the reactors. I think it was in the first reactor.

Sanger: They may have used it on one of them.

Weinberg: Yeah.

Sanger: Or built it at least.

Weinberg: Yeah, but they never did use that refrigeration plant.

Sanger: You know, the B Reactor is still totally intact with the control room still there.

Weinberg: Yeah.

Sanger: And I have been over there a couple times.

Weinberg: So you have seen the reactor?

Sanger: Yeah.

Weinberg: Those pigtails and well, Wigner was the one who made all those things happen.

Sanger: Yeah, it is a national engineering landmark now and they intend to keep it, ugly thing still, just a great big ugly concrete building. But they are over there sort of fiddling around decontaminating the back end where the slugs came out. I imagine it will be there forever. They wanted to make a museum of it, but I guess there is still enough irrational fear of radioactivity that people would not want to be that close to it, even though—

Weinberg: Well, I do not know. People come to the X-10 Reactor.

Sanger: Do they? Yeah.

Weinberg: Yeah.

Sanger: Of course, there really is not anything outside.

Weinberg: Yeah.

Sanger: Let’s see. Were these squabbles with DuPont very serious?

Weinberg: Well, yes and no. I do not think DuPont took them very seriously, but Wigner took them sort of seriously. The most extraordinary thing was this fellow, his name escapes me for the moment but it will come back. There was this fellow physicist who worked with our group for about three months. He was a theoretical physicist from I think it was New York University, or it may have been CCNY. And he got imbued with this anti-DuPont feeling that Wigner projected—somehow the idea that DuPont was dragging its feet or really interested in their future position. All this was really quite incorrect. 

So what this fellow did, he had a contact with somebody who was a close friend of President Roosevelt. And for about a week, this fellow—oh, what was his name, it will come to me. He disappeared from the project. I am wondering where the hell is what’s-his-name. Turned out that he had figured out a way of seeing President Roosevelt at the height of the war personally to complain that the project was not moving as fast as it should have because of the DuPont Company. Most extraordinary incident. He spent fifteen minutes with Roosevelt. Roosevelt did not know what the hell was going on and so he turned to Vannevar Bush, who was his right-hand science man and said, “Look into this.” 

And so Vannevar Bush then got hold of Jim Conant, you know, then became the President of Harvard and so on. And Conant was the liaison between the White House and the Project. And so Conant came storming down to Chicago screaming, “What the hell is going on with this guy?” And so I guess he [background noise] sort of a hard time. But Wigner never quite took Conant all that serious, I do not think. 

Conant was a most remarkable guy, but he was quite wrong on a very central issue. Conant said that as a chemist, he did not believe the chemical plant would work because the radiation would screw up all the chemistry. And he was entirely wrong on that.

Sanger: Well, that is what he thought.

Weinberg: Yeah. But this story, I wish I could recall this fellow’s name. It is on the tip of my tongue. But it was the most extraordinary incident.

Sanger: So he had a mutual friend with a President, huh?

Weinberg: Yeah, uh huh.

Sanger: You know, I was reading that official history and I think that is mentioned in there.

Weinberg: Yeah, it is mentioned.

Sanger: I do not think that the man’s name was in it.

Weinberg: He is dead now. He died—he contracted hepatitis and died at a fairly young age.

Sanger: But did that have any effect on Wigner’s squabble with DuPont?

Weinberg: Not really. And of course, you know, in a way, Wigner made up with the Dupont Company, and Wigner then was the Chief Consultant to DuPont in the construction of the Savannah River reactors. 

Sanger: Oh, he was?

Weinberg: Yeah, he took a year off and worked with DuPont on Savannah River.

Sanger: I believe Norman Hilberry told me that after all this fussing that at the end, Wigner said something to DuPont, which was something like, “Good job.”

Weinberg: Yeah, that is right, although just a few weeks ago, Wigner, who is pretty elderly now and his memory plays tricks on him, reverted to his original dislike of the DuPont Company.

Sanger: Oh yeah?

Weinberg: Yeah, yeah. And he and Greenewalt are good friends now, of course.

Sanger: [Laugh] What did you do then after the design was completed as far as the project went?

Weinberg: Oh, well, you see, the project then went on and looked at future reactors and we always were concerned with well, where would the business go if something went wrong at Hanford. Do we have a backup? But then we also started looked at nuclear energy for power and I got interested in pressurized water reactors. And I suggested, even during the war, that pressurized water be used for submarines. Then when [Hyman] Rickover came to Oak Ridge, I talked him into using pressurized water and that is how the pressurized water units got started.

Sanger: So you began to slip away from the weapons angle to something else.

Weinberg: Oh yeah, yeah, yeah, sure. Well, submarine was [interruption] when Truman was shown the models, he said, “Well, that is great, we have this peaceful use of nuclear power.” Although, of course, as you know, most of the reactors in the world today are pressurized water reactors. And Wigner was  involved in that in a very central way, also. 

Sanger: You, I take it, keep in touch with him.

Weinberg: Well, I had an interview with him just two weeks ago and something very interesting came up. You remember the Project got started with a letter from Einstein to Roosevelt. And the historians generally say that that letter was written by Szilard and signed by Einstein. Wigner said that was not it at all. He and Szilard went up to Einstein’s summer home on Long Island and Einstein had not heard of fission. Wigner explained it to him and in fifteen minutes, he understood it. Then Einstein began dictating in German the letter.

Sanger: Right then, huh?

Weinberg: Right then. And Wigner wrote it down in German. And Wigner says that he still has that original copy, which I imagine would be very valuable.

Sanger: Where is it, I wonder?

Weinberg: Well, he says it is among his papers and I do not know if he will ever dig them out. And then Wigner translated it into English, and that was the version that went to him.

Sanger: Oh yeah, I talked to him about that. I guess it all says that Szilard is the one who more or less put it together and Einstein signed it.

Weinberg: No, that is not correct, that is not correct. At least Wigner claims it is not correct.

Sanger: Yeah, well, I guess he would know. 

Weinberg: Well, you have to understand that although Wigner and Szilard grew up together and were very close, because Wigner’s views on and Szilard’s views were different, they gradually diverged. And towards the end of Szilard’s life—well, Wigner and Szilard sort of were somewhat estranged at the very end.

Sanger: Oh, were they?

Weinberg: Yeah.

Sanger: I mean, one of them was more what—friendly to the—?

Weinberg: Hawkish than the other.

Sanger: Who was hawk?

Weinberg: Wigner was the hawk.

Sanger: Oh. Yeah, I have heard a lot about Szilard, of course, and talking to these people.

Weinberg: Yeah. Well, Szilard was always sort of the gadfly. Szilard was marvelously imaginative but he did not really have the intellectual power that Wigner had. I mean, Szilard had a certain kind of genius in that he was extraordinarily imaginative and original. But Wigner had that, but he also had enormous scientific power. Meaning by this, that any problem that was sizeable, Wigner could solve it, yeah. Szilard did not have that capacity.

Sanger: Were Wigner and Fermi very close?

Weinberg: Yeah, quite close. I would describe their relation as cordial, although not really terribly close. But very cordial. They both respected each other totally.

Sanger: Wigner is not, would you say, to the general public is not nearly as well known.

Weinberg: That is right.

Sanger: Why would that be, do you suppose?

Weinberg: He is rather retiring and among physicists, Wigner is known totally. Well, Fortune magazine once described Wigner as “the quiet genius who single-handedly invented all of modern physics.” And physicists of that generation recognize that and so much of modern physics’ structure and so on goes back to Wigner. But his role in the Manhattan Project is not fully appreciated and the entirely central role that he played—you would not have had the Hanford on the time schedule that you did had it not been for Wigner. 

Sanger: Okay, one little thing. What was your feeling about—or other scientists’ feeling about—the Hanford Project? Was it mostly just a factory, would you say? Or was there a scientific angle to it?

Weinberg: No, no, it was a factory. But you know, as I say, we worked every single day including Sundays. We realized what the significance of what it was that we were up to.

Sanger: Have your ideas on nuclear weapons changed since then?

Weinberg: Well, I wrote a paper, which appeared in The Bulletin of the Atomic Scientists a couple of months ago, which I called The Sanctification of Hiroshima. What I said was, although I signed the front petition suggesting that when—make a demonstration, I never was all that concerned about dropping the bomb because I tended, and still tend to believe, despite the revisionist testaments of how many people, that it killed—that on balance, you probably saved lives by dropping the bomb rather than—although you can argue about that. It may have been even, Stephen, it may have been that you saved quite a few one way or the other.

But the point of my article was that the fortieth anniversary of Hiroshima is seen—what can almost be described as a religious outpouring of concern over the Hiroshima incident and all these meetings throughout the world. What I said is that it seemed to me that the bomb at Hiroshima is beginning to acquire a kind of transcendent significance, which can almost be described as having semi-religious overtones to them. And I said that I think that is very important and a very proper and desirable development because, as I put it, we are going to live with nuclear weapons forever the next fifty years, hundred years, thousands.