Nuclear Museum Logo
Nuclear Museum Logo

National Museum of Nuclear Science & History

Irénée du Pont, Jr.’s Interview (2003)

Manhattan Project Locations:

Irénée du Pont, Jr. is a member of the storied du Pont family and the son of the President (1919 to 1925) of the the DuPont Company’s predecessor, E. I. du Pont de Nemours and Company. The DuPont Company played a crucial role in the Manhattan Project; in 1942, DuPont was enlisted to design and build the project facilities at Hanford, including the B Reactor. Du Pont served as a member of the company’s Executive Committee. His second oldest sister, Margaretta, also married Crawford Greenewalt, a famous Manhattan Project scientist and chemical engineer who served as liaison between the Met Lab physicists and the DuPont engineers working on the B Reactor. In this interview, Du Pont discusses how Greenewalt first became involved with his sister and his family, and recounts stories of his father and the secrecy of the Manhattan Project.

Date of Interview:
November 1, 2003
Location of the Interview:


Tell us your name.

Irénée du Pont, Jr.: My name is Irénée du Pont, Jr. That’s spelled I-R-E-N-E-E D-U-P-O-N-T, comma junior. It’s like the girl’s name, Irene, which means peace, and Irénée is the French equivalent of the male Irene. Means peace.

Tell me how you are related to Crawford Greenwalt.

Du Pont: Crawford Greenwalt married my older sister—my second oldest sister. I had eight older sisters and she was number two in the lineup. Margaretta du Pont married Crawford Greenwalt.

How old were you when you first met him?

Du Pont: Well, he was part of a fixture around the house from my earliest memories. Yes, he drove a Model T Ford with a hole in the roof. That was very impressive at the time.

Was he in college when he started coming around?

Du Pont: He had met my sister at age twelve when they were both spending some time in Atlantic City. His mother and Margaretta and my aunt were sisters. So there was a family connection there. But I, of course, was not present when she was twelve years old. But I remember him, I guess, about at age four or five. 

How many years were there between you and your sister?

Du Pont: She is eighten years older than I.

He was the same age?

Du Pont: Yes, I think there was thirty days difference in their age. She was thirty days older than he. 

You were about four when you remember him?

Du Pont: I would say about four.

What else do you remember about him?

Du Pont: Well, he was very physically active. They would play hare and hounds on Saturday afternoons when work was out. He would come with the other group of young men that surrounded my sisters, and they would go running off on foot, playing a game or two. Would run away leaving blotches of torn-up papers where they’d been littering, and the hounds would try to find them. And they’d probably run five miles in an afternoon doing that. 

Was he through MIT at that point?

Du Pont: Yes. Crawford had graduated in the class of 1922 from MIT. I think he took an additional year to get a Master’s degree. So he came to work for the Du Pont company in 1923. He was working as an engineer at the plant in Philadelphia.

Tell us about his courtship of your sister.

Du Pont: Well, Crawford quite early in meeting my sister decided he wanted to marry her. But he had a great deal of competition, because there were many other Du Pont company engineers on the scene, and a young doctor and an older man who was my father’s contemporary. And so Crawford had to develop a strategy. So early on he decided he would get Margaretta aside from the group and say, “Gret, will you marry me?” 

And Gret would of course, “Oh, Crawford, don’t give me that nonsense. Forget it. Go away.” 

And then the next time they met he would say, “Margaretta, would you marry me?” 

And she’d say, “Oh, no.” Or some equal—put him off. And this went on for the best part of a year. 

And one day he said, “Margaretta, would you marry me?” 

And Margaretta said. “Yes.” 

“What did you say?!”

And then of course, the camera was cut off and we don’t know what happened after that. But in Crawford’s older years he used to tell that story about how he was totally surprised when she suddenly said, “Yes.”

What kind of marriage did she have?

Du Pont: Well, that courtship produced about as successful of a marriage as I’m sure could happen. They were devoted to each other throughout their entire life. I’m sure there were probably no misadventures of any kind involving a third party. They had a lot of fun, they knew a lot of contemporary couples of their own age. But they just had a wonderful marriage. And when my sister Margaretta came down with Alzheimer’s, Crawford was her nurse and he would not only take care of her twenty hours a day, 24/7, he did the cooking because she just liked the way he cooked better than what a hired cook would provide .

Can you talk about his diverse interests?

Du Pont: Well, Crawford knew a little bit about everything. In fact, you might say he knew a great deal about everything. Starting with music, he was playing the clarinet by the time he got to MIT. And then when they developed a little ensemble and somebody said, Let’s have a string quartet, but we have no cellom” so Crawford volunteered. He studied the cello and became a quite useful member of the quartet. 

He loved music. He loved shows. He loved to go to the theater, and as all the new television systems came on and methods of recording them, he was right there with the latest equipment to capture the shows that he enjoyed most on television. He figured in a show that one of our cousins developed, and made a home movie in which Crawford was the villain. I can remember the pictures of him being stripped of his clothes, down to the BVDs, and punished by the hero. But he loved to take on the difficult part of any event. 

Beyond the arts, he of course was very gifted in the studies for which he was prepared in college. He was a chemical engineer, graduated with a Master’s degree. And then in the nylon program for the Du Pont Company, he was one of the supervisors of the technical work that preceded the commercialization of nylon. His professor, Warren K. Lewis at MIT, would have been very proud of him, because Crawford invented a unit process, which is a step in the chemical engineering, and he made the machine which carries on the reaction where adipic acid is converted to the next step in the program. 

So Crawford invented the machine in which adipic acid in ammoniated to make adipinitrio, the next step in producing nylon. And it was a very clever machine. There were some spinning discs, rather like phonograph records but running very high speed in which molten adipic acid was dripped onto the disc and flung off into an atmosphere of ammonia. And that made a very difficult step quite easy in the process. It became my job when I was working at the plant some years later to maintain the Crawford Greenwalt machine which was—it was a bear but we kept it running and it was still making nylon in the early 50’s. So he could do everything very well in the technical department, extremely well, which was why he was chosen for this work under discussion today.

What type of an engineer was he?

Du Pont: What type of an engineer was Crawford? Why, he was both. He was a hands-on and he was a theoretical, both. You know, he could run an engine lathe up in his shop, and he made models. He could make objects that would be needed in the laboratory at Du Pont, and he also knew the theory from top to bottom. He was a good mathematician. And so he had both sides of the engineering issues covered, both theoretical and hands-on practical.

What type of people manager was he?

Du Pont: I guess the best way to describe the way Crawford managed people was that everybody that ever worked for him thought he was God. He was fun to work with, he could be firm when he had to be firm, and he was quick with praise when there was any excuse to give it.

So you see him as someone who could put those two groups together?

Du Pont: I think the reason he put those two groups together was because he had this gift of being both a thorough theoretical man as well as a hands-on, fix-it engineer. 

Can you talk about the xenon poisoning? 

Du Pont: Well, you’re asking me to talk about something where I was not present, but I did work for the Du Pont Company, and in most of their work they invariably over-engineered everything they did. They, for safety, and for reasons of covering unforeseen difficulties, if you needed a dozen, they’d make eighteen; if you need forty-two they’d make sixty-eight. They always erred on the overproduction side. I had the job of designing machinery when I first came with the Du Pont Company, and the first thing my boss said, “Now, you’re not working for airplanes anymore. You’re working for the Du Pont Company, and make it stout.” 

So apparently this prevailed during the design of the major reactor at Hanford, and in typical fashion, the Du Pont Company designed it with a significant margin of increase over the specified number of fuel rods to be put in the reactor. And of course that’s what saved the day when right after the first start-up, some byproducts were produced within the reactor, which poisoned the operation and caused the reactor to shut itself down. 

And Crawford knew enough about the theory of how this reactor was working that he thought he knew what the trouble was: that they were making this extra byproduct, which was a poison. And he had always wondered why it didn’t shut it down anyway. But fortunately, by utilizing the additional fuel rods that were designed into the reactor because of over-design, the reactor was able to start up and run successfully throughout its useful life.

Do you remember him saying he was more proud of the separations plant?

Du Pont: I wish I could help on that. No, I’m sure Jack Tepe or Bill Neff could easily tell you about that.

But in his older years, you know, he was invited to join the board of directors of the Boeing Airplane Company, which he did for the latter part of his life. And there he witnessed the development of the—help me now.


Du Pont: 707, 727, and then the 737 was the one that was their first real extension into highly technical development of aerodynamics. And they had spent a lot of research money developing the 737. That was after the 747, as it turned out. It didn’t come onto commercialization until after the 747. But when they got to the point of, “Which are we going to commercialize?” Boeing suggested that they shelf the 737 and focus on the 747, which was the big ship, where the 737 was for smaller and shorter flights. 

Crawford said to them, “Now look. You spent all this money on your research. Is it any good or isn’t it? You better go for both of them.” And they mortgaged the farm, as they say out there in the aircraft industry, and they did indeed develop both of them. 

Well, the 737 was Boeing’s nylon. That was the one that really made money for the Boeing Company. And after the 700th copy was made, Crawford by that time had retired from the board, but they invited him to come back and celebrate the 700th copy of the 737, which was their real financial success in the company.

Can you sum him up?

Du Pont: I don’t think Crawford would admit that he was conservative. He just wanted to be damn sure it succeeded [chuckle], which was the way he worked. He did his homework, and he determined ahead of time whether it would work or wouldn’t. And when he decided it would work, the forces of evil couldn’t stop him.

That’s what he was working against. Did he ever talk about the feeling people had during the Manhattan Project?

Du Pont: Yes, Crawford—among all of the people I’ve known that ever worked on the project—agreed that in their minds, the Germans were going to drop the bomb any minute. 

And of course, as you already know, he spent June 6th, 1944 listening to the news to see whether the Germans were going to drop the bomb on the invaders at Normandy. They didn’t. But it was—no question about it—the motivation behind the whole Hanford effort was patriotism. They didn’t for one moment think of whether they were going to get paid or not. It was purely a matter of, this is what we’ve got to do to support the people that are out there fighting this war. 

Can you tell the story about when he was absent that Thanksgiving?

Du Pont: Well, yes, I was a senior in college and I came home to my parents’ place in Delaware from Massachusetts to have Thanksgiving with the family. And I think we had to go to school that Friday following, but I cut classes so as to be with my family. And there was a nice gathering with most of my seven older sisters present and some of their husbands who weren’t away fighting. 

And someone said, “Well, where’s Crawford?” And this, you realize, was the fall of 1942 when the Du Pont Company had just been called upon to investigate and work with the Manhattan Engineer District. 

And my father said something that he certainly shouldn’t have but he didn’t know any better. My father said, “Oh, Crawford is out working on a bomb so terrible that it will end the war.”

And there was sort of silence. And my sister Margaretta didn’t react, that I could see, I wasn’t looking at her, but the subject wasn’t discussed. 

So again, I came home for Christmas a few weeks later and I said, “Hey, Dad, what about this bomb you mentioned that’s so bad that it would stop the war?”

My father looked sort of blank. “I don’t know what you’re talking about.”

“Well, you said something at Thanksgiving.” 

“No, I did not.” 

And I could tell by his expression that that ended the subject. So I figured maybe I had dreamt it or something. And it wasn’t until after the war, of course, that what Crawford was doing was cleared up.

Your theory was that he told your sister and your sister told your dad?

Du Pont: Yeah, I think maybe you can speculate very definitely what happened. When my father made this mistake, my sister Margaretta heard it and told Crawford what my father had said. And so Crawford said, when he got back to Wilmington he went to my father’s older brother, Pierre Du Pont, and he said, “Pierre, I’ve got a problem.” He said, “If Mr. Bus,” as they called my father, “has broken the secrecy agreement, somebody ought to tell him that he shouldn’t do that. And I’m not going to tell my father-in-law, so maybe you’re the one that ought to.”   

And the bigger brother had words with my father between then and Christmas, so that by Christmastime there was full secrecy exerted.

Was there any debate about leaving Hanford after the war?

Du Pont: Well, that was about the time I was being hired by the Du Pont Company. I had worked for an aircraft engine company prior to that time, and so I really wasn’t in the position to hear any of the strategy, or what the executive plans were doing. I was working in North Jersey somewhere and not tuned in.

Anything about his ability we’ve left out?

Well, Crawford spoke with a very deep resonant voice, so you could tell who was talking a long way off. 

I remember my father had a special kind of pneumatically operated thermostat to control the temperature of the house. This was because the house was built before the days of the usual Honeywell-type thermostats that we’re all familiar with, and it would release a little hissing sound of air. And the house got cold one Sunday when there was a family gathering, and so Crawford and I went down in the basement to look at the air pump. And we traced all the pipes and we did everything to see why the house wasn’t getting warm when the furnace was running, and so he came back up and explained to my father and he said, “My diagnosis is.”


Copyright 2013 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.