The Manhattan Project

C. N. Gross's Interview

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A native of the West Virginia mountains, C. N. Gross came to Hanford in January, 1944, from Wilmington, to be a reactor consultant. He and his wife decided to stay after 1946 when Du Pont left and General Electric took over. They liked the atomic energy business as well as the Eastern Washington sunshine, and GE offered a good job at a time when Du Pont management people were stacked four deep on the East Coast. In this interview, Gross elaborates on his role in the building of the Hanford reactors as a contact man between operations and construction. He discusses the mechanics of the reactors, and also describes his reactions to the bombs being dropped on Hiroshima and Nagasaki.
Manhattan Project Location(s): 
Date of Interview: 
July 3, 1986
Location of the Interview: 

[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:

When I came I was working as contact man, liaison, between operations and construction. I think I was called construction consultant for operations at all three reactors. I made sure construction followed the blueprints. The teletype between Hanford and Wilmington was going 24 hours a day on design changes. You have to give credit for a lot of the original ideas on construction of the reactors to the Met Lab. They did a whale of a good job, and Du Pont picked it up and it is almost unbelievable to me today that Du Pont did what they did in two years.

I was aware of what was going on. I was told in Wilmington in '43. I spent about nine months there working with the design people. I looked at blueprints and suggested ideas on how best to build a plant we could operate. I remember helping with the design of the control rods, that moved in and out on racks, and were water-cooled. The control rods were horizontal and controlled the reaction. The vertical rods, the safety rods, were used if we had an electrical outage. The safety rods would automatically drop. The safety rods were not used to control the reaction because they would not withstand the heat. They were not water cooled. The nine control rods had tubes inside them, connected with water. When the rods were pulled out of the reactor they were radioactive so there had to be a shielded control room.

We had fuel elements that ruptured. After a fuel rupture, the reactor may or may not shut down automatically. But you would know you had a rupture. The fuel tube itself would overheat and each tube was monitored. That was a main reason for shutdown, except for shutdown for unloading of fuel elements.

Unloading was done with computers, although they weren’t like the ones we have nowadays. You would figure that certain tubes at certain temperatures that had been operating so long had produced so much plutonium and they were ready for discharge. The Tubes on the fringe would take a year or so to get ready. The ones in the center might take only three months because of greater neutron availability.

The design level for plutonium production per reactor was 250 grams a day, when the power level was 250 megawatts. Each megawatt was supposed to produce a gram of plutonium per day. But that was ideal, and the reactors did not produce that much a day in operation. What came out of the separations area was far less than that a day.

The bombs, well, I more or less took the news as what is to be will be. I felt like, when they were dropped, that the war was effectively over. I don’t’ know it was really necessary to drop them on cities, but they did what they were supposed to do, end the war.


Full Version: 

S. L. Sanger: Charlie Gross, July 3, 1986 in Richland. You were reactor supervisor?

C.N. Gross: Well, I had several jobs. But the first job that I had in the reactor area was being the chief supervisor of D Area.

Sanger: That was when?

Gross: December of 1944, I believe. I do not remember positively.

Sanger: Is that when you came here?

Gross: I came here January 1 of 1944, from Wilmington.

Sanger:What did you do when you first came out here?

Gross: I was really working as a contact man between operations and construction.

Sanger: Is that kind of like what [W.K. “Mac”] MacCready was doing with the separations?

Gross: Yes, right.

Sanger: Kind of a construction consultant?

Gross: Right.

Sanger: For operations?

Gross: I think that was what I was called.

Sanger: Is that at all the reactors, or just the one?

Gross: No, all of them.

Sanger: All of them.

Gross: But when the time came to start up the D Reactor, I took over the job as chief supervisor of D. I gave up the construction liaison.

Sanger: During the construction phase, what status were the reactors in—B, 100-B in—when you got here?

Gross: 100-B was coming out of the ground under construction. It was fairly well along. I mean the walls were pretty high. D was coming along. F, I think, we were just talking about getting it started.

Sanger: But the graphite had not been laid down yet in B, probably?

Gross: No. I do not know when it actually started. But the graphite work machining, mockup for the graphite layout, was at Hanford.

Sanger: What were you doing mostly? Just making sure that the construction was following the blueprints?

Gross: Right, right. But even so, most of the dealings actually did not go through me. The teletype was going twenty-four hours a day between Wilmington and Hanford. The construction people got their information from Wilmington on whatever design changes there were to be made.

Sanger: Do you know if there were very many design changes?

Gross: Oh, there were design changes all the time.

Sanger: All the time.

Gross: Yes. But you have to give credit for a lot of the original ideas for the construction or the building of the reactor to the Met Lab. If you read the feasibility report, a lot of the ideas that were put into practice actually were suggested by the Met Lab people. They did a whale of a good job.

But DuPont picked it up. It is almost unbelievable even to me today, having gone through it, that DuPont did what they did in two years. Of course, Ray Genereaux and the other design people, construction people, that you have talked with have told you the same thing.

Sanger: I talked with Frank Mackie, too.

Gross: Yes.

Sanger: He is in his eighties now. He lives in a retirement center outside of Wilmington. He was quite helpful. He was not here all the time, of course, because he was in charge of other projects too. But this was the biggest.

So you did that for about one year, the consulting or the liaison, from January until December or so, ’44?

Gross: I guess that must be right. But I never thought of it being that long.            January of ’44 and D Reactor – well, of course, I left the liaison work much earlier than December, because we went into the actual working, the loading of the reactor. I am having trouble remembering all of the details. So it must have been the middle of the year or August/September when I was moved from that position to where I was chief supervisor of D Reactor.

Sanger: Did you take part in the loading of B?

Gross: Not really, because at that time, when B was being loaded, I was still working as a liaison for construction. I am trying to think who the chief supervisor was at B. I do not remember.

Sanger: You would have helped, I suppose, with the loading of D, though?

Gross: Yes. Examination, seeing that it was done according to the way we understood that it should be.

Sanger: D would have started up about then?

Gross: December.

Sanger: In December.

Gross: I think that is right.

Sanger: I can look that up. By then, you had overcome the problems of the Xenon poisoning. I suppose that you knew how to do it?

Gross: They got got around it in B [inaudible]. A lot of thanks goes to the DuPont people, Dr. [Monte] Evans in particular, where they filled in the corners of the reactor, to overcome the Xenon poisoning.

Sanger: You were at D then, until the end of the war?

Gross: No, after chief supervisor in D, I was promoted to the production superintendent. But I do not know the dates on that. I have some things that we could look it up. But I do not think the dates make much difference.

Sanger: No, they are not too important. That was the 300 Area, you mean?

Gross: No. The production superintendent had the 300 Area.

Sanger: Oh, I see what you mean. You had the reactors.

Gross: Right. I was supervisor of the P Department—that is “Pile.” Then I was supervisor of both separations and P&S Department. That is “Pile and Separations.” The years, I cannot tell you. But ’44, ’45, ’46, ’48, year of the flood.

I think manager of manufacturing at that time, the flood time. But Bill Johnson and I did not agree. He put Emmet Baylor, I think it was Emmet, in charge of manufacturing. And I became manager of employee and public relations.

Sanger: That was long after the war though, right?

Gross: Yeah, ’55. I think it was around ’55.

Sanger: When you say you were supervisor of D, that means the entire plant there?

Gross: Yes. No, because maintenance is with a separate organization, but they did not report to me. But the operating people that operated the reactor reported to me.

Sanger: Did you have much direct connection with say the operation of the reactor itself? As far as having done it yourself, say, in the control room?

Gross: Not really. I did not start up the reactor. I did start up C Reactor, when it was started up.

Sanger: That was after the war?

Gross: Yes, but that was just more of a gesture than actual operation, because they had already started it, I mean, tried it out to see if it would work and all, before we were in town and we went out there and started up it some morning.

Sanger: You had mentioned, when I talked to you before, that you had worked with or you had met [Enrico] Fermi, right? That was at the Met Lab around here?

Gross: Not out here. It was on a trip back east to the Met Lab. One morning, we went into the reactor they had at Argonne. Up on top of the reactor were Fermi and – not [John] Wheeler. John Wheeler was one of the physicist professors at Princeton, I think. But he was on the project. Fermi’s mathematician lady—

Sanger: Oh, I know who you mean. Was that [Leona Marshall] Libby?

Gross: What?

Sanger: Not Libby?

Gross: No.

Sanger: I know whom you mean.

Gross: I want to say Wheeler, but that is not right. Anyway, they were up there. They introduced us around. They were all excited, thrilled, that they had just reduced the speed of the atom to almost zero that night. Someone asked if we were physicists. We told them no, we were chemical engineers. Well, they did not have much to do with us after that.

Sanger: Is that right? Yeah, I think you mentioned they did not.

Gross: Oh, did I?

Sanger: Yeah, you did mention, they did not think that chemical engineering was much of a profession, as far as physicists were concerned.

Gross: That is correct.

Sanger: You had a degree in chemical engineering, then

Gross: Yes.

Sanger: From where?

Gross: North Carolina State University.

Sanger: Oh, that is right. Yeah, you told me that. And you had worked for DuPont. Where did you go to work for them originally?

Gross: At the Belle, B-E-L-L-E, Plant in West Virginia, there at Charleston.

Sanger: Now what did they do there? Was that ammonia?

Gross: Ammonia. Well, that was just one of several, dozens of products that they made there. They also synthesized alcohol, mostly methyl. But there were some ethyl side products, isobutanol and some of the other alcohols.

Sanger: Where were you living during the war time period? In Richland? Were you living in town?

Gross: Yes, here in Richland. We lived, for two or three months when we first came out here in January of ’43, in Yakima. Well, my wife was in Yakima. But we would come to Richland and live in the dormitories.

Sanger: What was it like out there at the reactor sites when you first got there? Was it really a busy, busy place?

Gross: Oh, it was very busy, with people all over the place. But it was also very dusty.

Sanger: Was it?

Gross: We had some real dust storms in those days. But sometimes you wonder how people knew what to do. I mean, it was just a lot of activity.

But one of the things where it was so crowded was even in Hanford, where there were hundreds, thousands of workers. Sears came in with a store. I understand it was sold out on the first day.

Sanger: Oh, yeah?

Gross: Yeah.

Sanger: Somebody told me that the construction workers tended to wear their overalls until they could not stand it, and they would just buy a new pair because there was not a—

Gross: I do not remember anything like that.

Sanger: Of course, there are all kinds of stories.

Gross: That is right.

Sanger: You were aware, I suppose, of what was going on?

Gross: I was told in Wilmington in ’43. I spent about nine months in Wilmington working with the design people, the engineers, the design people to give us something that we could operate. 

Oh, about nine months in Wilmington, and then we came out here.

Sanger: Did you go to Oak Ridge at all?

Gross: Only on visits. A lot of the people were down on the training sessions. But we were in Oak Ridge once in a while, but on visits only.

Sanger: You did not go there to learn much from that reactor?

Gross: No.

Sanger: Because you were, I suppose, basically interested in making sure that the construction was following the operation, the design?

Gross: That is right.

Sanger: That is why you had spent a lot of time in Wilmington looking at blueprints?

Gross: That, and giving ideas as to how to design a thing that we could operate. I remember working with a fellow by the name of Petrescu, one of the engineers, and a fellow by the name of Smith, where we actually helped with the design of the control rods, that moved in and out on racks, water-cooled. Just giving ideas as to what might work, so they could design it. The vertical rods, I remember working on ideas on how to get the vertical rods to work.

Sanger: Were the verticals rods referred to as safety rods?

Gross: Yes.

Sanger: The control rods were horizontal? Those were the ones that they used to control the reaction?

Gross: Right.

Sanger: When would they use the other ones, the verticals?

Gross: If we had an electrical outage, the vertical rod would automatically drop.

Sanger: But they were not used to control a reaction at all?

Gross: No, they were not.

Sanger: Up or down?

Gross: That is right. They would not have been able to withstand the heat to put them, in because they were not water coolant.

Sanger: Oh, I see.

Gross: The control rods were water-cooled.

Sanger: How many control rods were there?

Gross: Nine.

Sanger: Nine?

Gross: Yes.

Sanger: And they ran through water-cooled tubes?

Gross: They had tubes inside of them that had water connected to them. The hose were wound up on reels. When they were withdrawn, they would wind up on reels, so that the hose would come on out, because they had to go through what they called inner rod drum.

Because when you pulled rods out of the reactor, they would be radioactively hot. So you had to have a room where the rods would be pulled into, out of the reactor, and would be shielded then from the people that were around.

Sanger: What if something broke down? How could you fix that?

Gross: They had to shield the rods. I do not remember exactly how they did that. But we did have to replace them from time to time. They would have a cask that they would pull the rods into, a steel cask. They would seal the ends and then put a new one in.

Sanger: Was there much trouble mechanically with the reactors?

Gross: So-so. I do not remember having too much trouble, until the graphite started to expand.

Sanger: That was later, though?

Gross: Yes. Then we had lots of trouble with the rods.

Sanger: Is that what interfered with the control rods, the expansion?

Gross: I do not remember ever having trouble with the control rods themselves. But they must have had some trouble. The tubes would expand like the fuel [inaudible], and then come back down. Later, they got them hot enough so that they could cure that. There would be two of them, so they had the contraction.

Sanger: Yeah. I guess the reactor did have quite a few mechanical aspects to it.

Gross: Oh, yeah.

Sanger: Inert gas was put in, too.

Gross: Helium.

Sanger: That was because it did not capture neutrons?

Gross: That is correct. It was to have a positive atmosphere that would not absorb neutrons. But if they had air, they would absorb neutrons. But I think it would also become radioactive.

Sanger: I see. Because helium was inert, so it would not—

Gross: Right.

Sanger: —react to it. Then there was a special section, wasn’t there, that performed that duty of keeping helium in the reactor? Because somebody was telling me they worked in a part of the reactor operation that was the helium gas.

Gross: That is true. An extension from the reactor building itself, the helium lines circulated through the reactor, went out to a helium building, the helium operations, where they added helium and circulated it through filters. I do not know why. I do not remember what all was there. But it was a separate building, from the reactor building itself.

Sanger: Did you have much—at least, do you remember in the early days—much trouble with fuel element breaks or ruptures?

Gross: We had fuel elements that ruptured. And we had – I am forgetting things. But most of the time, we were able to discharge them into the pool of water.

Sanger: Far—on the other side?

Gross: Far side, yeah, the far side of the reactor. Then we would pick them up off of the floor, put them in casks, and send them to the 200 areas.

Sanger: Would you have to shut down for that?

Gross: Oh, yes. For a rupture, it may or may not shut down automatically. I am trying to remember how you would know that you would know you had a rupture.

Sanger: Could you tell from that bank of fuel tube lights?

Gross: Not that you would have a rupture.

Sanger: You could not. Would it overheat?

Gross: Yes. The tube itself would overheat. Every tube was monitored, of course.

Sanger: Would that be one of the main reasons for a shut down—

Gross: Yes.

Sanger: —that was unwanted, a fuel rupture?

Gross: Yes. But the main reason for a shutdown would be the discharge of fuel elements. It would ship to the 200 areas, separations area, for the separation of plutonium from the—

Sanger: Do you remember, would you have to unload the entire reactor? Or would it just be part of it?

Gross: Just part of it.

Sanger: And then you would load new in that, and then you would go on.

Gross: That is correct, yes. That was all done through computers, although we did not have computers in those days like we have today.

Sanger: Yeah, calculators, maybe or something.

Gross: But it was figured—you would figure, I never did—that certain tubes at a certain temperature after operating for so long would have produced so much plutonium, and they were ready for discharge. So they discharged the various tubes in the various sections of the reactor. The ones on the fringe would maybe take a year or so.

Sanger: Oh, but the ones in the center—

Gross: Center would be ready sooner.

Sanger: What would it be? A couple months? Do you remember?

Gross: No, I do not. It seemed like three months to me.

Sanger: Yeah, for the ideal, I mean, the quickest. Because the ones out at the ends did not get the neutron production?

Gross: No, that is right. You have done a lot of work on this.

Sanger: Well, I have read about it. Yeah, you pick up a lot talking to people and reading, of course. Did the cooling system seem to work pretty well?

Gross: Yes. We did not need a demineralization plant. It was only built at B – no, at D, I guess it was.


Sanger: And you did not use it?

Gross: No, we did not have to.

Sanger: That was the beautiful pipes and all that?

Gross: Rubber-lined. Or neoprene-lined.

Sanger: That would cost quite a bit of money, I guess.

Gross: You are not kidding.

Sanger: And they never had to use it?

Gross: No.

Sanger: That is because the river was pretty clean?

Gross: Yes, I think that is part of the answer. But the water did not get so radioactive that we would have to use it, because it did not have the material in it that would become radioactive, as much as it could.

Sanger: Yeah, I have heard somebody talk about it. I guess Norman Hilberry. I talked to him, too. He was talking about that demineralization because he said, “If you did not need it, you did not need it. But if you did need it, it would not work otherwise.” So they decided to be on it.

Gross: It was just insurance.

Sanger: So in other words, there were not too many problems, mechanically, at least, with the reactors after they solved that Xenon problem. I talked to [John] Wheeler. Did you know him at all?

Gross: Yes.

Sanger: Well was he a fairly well-liked guy?

Gross: From the way I read it, yes. He was a professor at Princeton. DuPont picked him up as a consultant.

Sanger: He had a very early important role in fission.

Gross: Yes.

Sanger: As a very young man.

Gross: I did not know that.

Sanger: Yeah, he had wanted to be an engineer once. I guess that is one of the reasons he got along well with the engineers, because he thought like them. He could talk their language. He apparently was not as arrogant as some of the physicists were.

Gross: I always liked him. He was very nice to me.

Sanger: I talked to him. He is at Texas now.

Gross: Texas.

Sanger: University of Texas. He left Princeton quite a number of – eight or nine years ago. But he was probably at retirement age, practically. Texas is incredibly rich. So they would pay these people huge sums to come. He is the director of the Theoretical Physics Department or whatever.

He was actually quite charmed with Hanford. I mean, he liked it out here. He was kind of romantic about it, even. That was one the reasons I talked to him, because you can read about most of what he did. But I wanted to ask him what it was like and what his recollections were. He had some pretty good stories about it. He was here for about a year I, guess.

Gross: Yes, that is what I would have guessed.

Sanger: I guess he was the leading physicist who was in residence.

Gross: I think so.

Sanger: He was an interesting guy to talk to.

Gross: Very much so.

Sanger: I guess he is in his mid-seventies.

Gross: Johnny [John Wheeler]?

Sanger: Yeah.

Gross: You think he was younger than I am? I thought he was older.

Sanger: Maybe he is seventy-six or so. How old are you?

Gross: Seventy-eight.

Sanger: Yeah, I think he is a little younger, although I could be wrong. He is mid-seventies.

Gross: In all of the people that you have met, have you talked with Thor Hoff?

Sanger: No, but his name came up yesterday. Now he was what

Gross: Well, I do not know. Mostly, from what I remember, he was connected with the security. But he was not a security officer, but the classification of the papers.

Sanger: Oh, he was, yeah. [W.K.] MacCready said that this man had been working on a – he collected documents for a history, years and years ago for DuPont.

Gross: Oh. Thor Hoff?

Sanger: Yeah, and DuPont does have a history of Hanford that they have never published. It is four huge volumes back in Wilmington. It is mostly technical; not much personal data in it at all. They never mention the word plutonium once, of course.

Gross: Yeah, right.

Sanger: They just talked about the process, the product, and so on, never what they were doing. How many people, would you estimate, would have known what was going on? I mean, ten percent of all the thousands that worked out there?

Gross: Steve, I do not know.

Sanger: The DuPont people at your level knew, of course.

Gross: Right. But if you are speaking of ten percent of fifty thousand or so that were out there—

Sanger: Maybe that is too many.

Gross: Yeah, I think that is too many.

Sanger: Yeah, that probably is. Most of all the other fellows below a certain level, they did not have a clue.

Gross: Yeah, that is right.

Sanger: Even the guys in the reactors’ control rooms did not know what they were operating. They claim at least at that time, they did not. I was talking to this guy, Miller. Do you know him?

Gross: Johnny Miller?

Sanger: Jack Miller.

Gross: No. I know a Johnny Miller. I do not remember a Jack Miller.

Sanger: Well, he is down here. Or is he down this way, I guess. He was a reactor operator at B, I think. He said they thought they were making rocket propellant during the war.

Gross: I am surprised that the operators did not know. Well, I guess they were just never told.

Sanger: I suppose maybe the supervisors might have known.

Gross: Yeah. Oh, yeah, I am sure the supervisors knew. But the operators maybe did not.

Sanger: I think when I talked to you before, you said you were coming on a train from Spokane and saw the desert. You said you were from West Virginia?

Gross: That is correct.

Sanger: You thought that maybe they could have used a few more trees around. What made you decide to stay on?

Gross: Mostly because I was certain that the atomic energy business would continue to grow and that we would get electricity from it. But also, we liked the area here. We liked the sunshine. Maybe the important thing was that DuPont would take me back to West Virginia, or some other place. But I was told to remember they were stacked up four deep.

General Electric came in and offered me a nice job. We liked it here, both my wife and I. So the biggest reasons, I think, was the fact that we had a job here. But we also liked it here, as we like it right now. We are trying to look into the possibilities of a retirement home.

Sanger: Here?

Gross: Yes, I would like to be here, yes.

Sanger:Do you remember your feelings, if you had any, in reaction to when the bombs were dropped, when they were announced?

Gross: We just more or less took it as a matter of, what is to be will be.

Sanger: I used to ask people if they ever had any regrets about it. But I have noticed that frankly the only people who even want to discuss that were a couple physicists back East. Generally, and maybe this is not your view, but people here just thought that it was fairly natural, and it was a way to end the war more quickly than perhaps it would have otherwise. Is that your feeling, about the use of the bombs?

Gross: Well, not quite. I felt when it was dropped, that the war was effectively over.

Sanger: The first one, or both of them?

Gross: Well, they were only three days apart.

Sanger: Yeah.

Gross: I think three days apart.

Sanger: The sixth and ninth, yeah.

Gross: So I do not know that it was really necessary to drop them on cities. But it did what it was supposed to do, end the war.

Sanger: Those people have made a career out of that, wondering if they stopped or if they ended the war themselves. The historians, I mean, there have been several books written on that. Apparently, the feeling by a lot of them is that the first one was all that was needed. On the other hand, other historians had noted that the Japanese were not ready to end the war even after the first one.

But the second one came fairly quickly and no one knows. Since it happened, you cannot say, “Well if this had not happened, it would have been this way,” because the Russians entered the war too, the same day the Nagasaki bomb was dropped. That upset the Japanese, the fact that the Russians had come in. That was thought to have to have played some major part in making them decide to quit. Although the Emperor, I had noticed, that in the radio broadcast he made mention of the bombs as being a big reason for ending it.

Gross: I would think so.

Sanger: Because they had a little trouble, I think, absorbing the magnitude of these weapons that quickly. But I think it is clear. It seems to me that they played a very big role in it, that the Japanese probably would not have surrendered without that, or without an invasion.

Gross: That is right.

Sanger: Which would have been—

Gross: A lot of people.

Sanger: —a lot of people killed, including Japanese. More than were killed by the atomic bomb.

Gross: I agree with you, Steve.

Sanger: But it is a fairly complicated question.

Gross: It is.

Sanger: Maybe it does not really mean anything. I mean, because it has happened. The idea was that they were weapons and they were going to use them. They were killing as many people in Tokyo in those big firebombing raids earlier, as either atomic bomb. The only thing about the bombs, of course, is that people are worried about the radiation and the genetic effect.

Gross: Effects, yes.

Sanger: Which apparently were not as major as they had thought.

Gross: That is my impression, too.

Sange: Generally speaking, I guess anybody who would have been affected genetically was killed because they were close. And all of these studies that show leukemia, but not much else.

Gross: Right.

Sanger: That has been a long time now, a generation or more. But some of the physicists were morally upset. Although I have read, even the ones who have certain regrets now, at the time, said that they understood why they were used in the context of the time, which was the war, to get it over.

Gross: Right.

Sanger: I think that some people think that the United States used them to impress Russia. But the thing was that the Russians knew it. So that is why Stalin was not.

Gross: He was not surprised.

Sanger: He was not surprised.

Gross: No, that is right.

Sanger: Particularly impressed. But anyway, that is all moot and academic anyway. But people are interested in that. But people told me, “We did not think about that then. We just wanted to get the thing over with.”

Gross: That is right.

Sanger: And, of course, anybody who was in the Pacific getting ready for the invasion, which was not too far off, they were overjoyed.

Gross: That is right.

Sanger: Somebody said in a book I read, “Now I knew I would live to be an adult.” And people had brothers there.

Gross: Right.

Sanger: In fact, a professor at the university who teaches history of the atomic bomb said that every time—he hears from students a lot, that their older uncles and whoever said they loved the bomb because it ended the war, as far as they were concerned.

Gross: I think most people feel that way about it, that it definitely helped end the war.

Sanger: Yeah. It might be too simple to say it ended it. But people think it did, because the bombs were used and then in a week or so, the war was over. Or even less than that, the Japanese had accepted the terms.

Gross: I did not know at the time. But I understand we would not have had another bomb ready for some period of time.

Sanger: Yeah, well one of the books I read mentioned that they used up all the uranium. So that was gone. But that Hanford was producing enough plutonium that they would have three more ready by, I think, the following month.

Gross: The following month?

Sanger: I think so, yeah. Because by then, they were a real factory. That is what one of these books had said. But the uranium was gone. They had used up every speck of it, apparently.

Gross: That sounds reasonable.

Sanger: Because it was so laborious. I believe they had to use 130 pounds or so in that gun-type bomb with the uranium, and only thirteen – [General Leslie] Groves said 13.5 pounds of plutonium for the Trinity bomb, which was the same really as Nagasaki. The reactors were designed, according to [Dale] Babcock, to turn out 250 grams of plutonium a day, each one.

Gross: Each reactor?

Sanger: Each reactor, when they were going full speed.

Gross: That was the level that we were operating, 250 megawatts. And it took a megawatt to make one.

Sanger: Oh, is that the way it was figured?

Gross: I think so. But that was whole reactor, you see.

Sanger: Yeah, and that was ideal, I suppose.

Gross: Right, but it would not be 250 a day. That is correct if you say, how much did you produce total? It would be 250 grams for a twenty-four hour day. But that would be if you took all of the fuel elements, dissolve them, and separate them out. What came out of the line from the separations area would be far less than that.

Sanger: Far less than that. Well, that is what I figured. By the time they had three of them going—

Gross: Yes, B, G, and F.

Sanger: Yeah, they could make a lot. They only needed about twelve or thirteen pounds of it [for] a bomb.

Gross: I did not realize they needed so many pounds of it.

Sanger: I did not either. But I think it was because it was really inefficient. They probably used more than they would have had to. That is an unofficial figure, which I read in the Washington Post during the anniversary of the Trinity test.