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Richard McCardell’s Interview

Manhattan Project Locations:

Richard McCardell was a nuclear engineer at the National Reactor Testing Station in Idaho. In this interview, McCardell explains the path he took towards his involvement in the Special Power Excursion Reactor Test, or “SPERT,” which was a series of reactor tests in Idaho Falls.

Date of Interview:
September 15, 2004
Location of the Interview:


Cindy Kelly: We’ll start with a very simple question, which is what is your name and spell it.

Richard McCardell: Okay. Richard McCardell. Last name is spelled M-c-C-a-r-d-e-l-l.

Kelly:  Great.

McCardell: I’m from Pocatello, Idaho. I was born, raised, and educated there. I moved to a farm from the city, because I pestered my parents because I wanted a horse. I pestered my parents from the time I was about three years old, until we finally moved on a farm when I was seven. I didn’t realize how much work there was going to be on a farm. I just knew I wanted a horse.

I worked on a farm as a youngster, and found that I just got my board and room for working on a farm, so I started working at a job when I was really quite young. I was about thirteen. I sold subscriptions to a newspaper for a year, and I worked in the Bannock Hotel. Now, there’s a memorial there, to the Bannock Hotel in Pocatello. I worked in the kitchen there for a year, and then I went back and sold subscriptions for a year all over Utah. Actually, I was in Las Vegas when there was almost nothing there, in 1951. I was there for about five weeks. We were selling Sunday-only Salt Lake Tribunes.

That summer I came back to high school as a junior, and went to work for the railroad in a forty hour-a-week job. I was around farm equipment when I was really young, and then I was around steam engines. At the time that I went to work for the railroad in 1952, they were changing from steam engines to diesel-electric units. I got to work on both as a laborer and then eventually, I became an electrician helper, which means you do all the work and the electrician signs all the papers. At least, that’s what it meant on the night shift, because I worked night shifts all the time because I was going to school.

I worked at the railroad four years. I dropped out of high school. I decided I had enough education after I went to work for the railroad, and I was making a big salary, almost as much as my father, and I was fifteen. I dropped out of high school. I didn’t like some of my teachers. I worked there for a year and decided I didn’t want to do that the rest of my life, so I went back to high school. I worked at the railroad nights for two more years, until I graduated from Pocatello High School.

I got married when I was eighteen. I was madly in love, but I married a young lady who had two children, so by the time I was going through college, four children. She and I had a boy and a girl. I worked at the railroad through my freshman year of college almost to the end, and then I got laid off because they moved the back shops from Pocatello to Salt Lake City. Most of the electricians moved to Salt Lake City, or a lot of them. Those who stayed in Pocatello could, what they call, “bump down.” That means that the one who was the youngest ended up without a job, eventually, as they bumped down.

Then I worked for Kraft Foods Company as a cleanup person. For my sophomore and junior years, I found I couldn’t take seventeen to nineteen credit hours after a year or so, and I dropped back to twelve credit hours. It took me five years of undergraduate school. Of those years, my final year, my parents were able to help me. I worked two jobs in the summertime, so I could make enough money for my tuition and books. Then I worked just forty hours a week and went to school during my undergraduate years.

One year, I drove a school bus and worked twenty-eight hours a week. I had some very wonderful people who helped me along the way. Paul Wilike, who was the manager at the Kraft Foods Company, worked around my college schedule. He let me work around my college schedule. Sometimes I had to take night classes, because we didn’t have anybody to teach theoretical physics at ISU and only had people come from the Site. They had a person come from the Site to teach theoretical physics at night, so I had to move my work schedule around. He was very good to help me. My senior year of college, my parents were able to help. They paid my tuition, and they gave us $100 a month. Then I worked part-time, twenty-eight hours a week, for my senior year.

My first year of graduate school, same thing. I had a graduate assistantship, and I also had a job taking care of an all-sky camera for the International Geophysical Year, which kept going on year after year. They were looking for auroras, the aurora borealis, so we had an all-sky camera. We had a parabola at the bottom that reflected the light to a mirror on the top, that then reflected it down to a camera. The camera had to be covered in the daytime, uncovered at night, and the film had to be changed once a week, or something like that. I had that job, besides being a graduate assistant, and I taught sophomore physics laboratories.

I graduated in 1962, and that’s when I went to work at the Site. I had been on tour at SPERT at the site when I was a senior in 1960. I knew a little bit about it, and I had a friend, who graduated in undergraduate school with me, who went to work at SPERT. He actually is the one who talked to Kurt Hare about me. I had an application in, but Kurt called me at work. It was interesting. I was really busy on my thesis, and they sent me on offer. I thought, “Well, this is a good job. I’ll take it.” But I never did write back a letter to say I accepted the offer for a while, because I was busy. So they sent me another offer, which was higher. I was quite shocked by that.

I went ahead and accepted. When we first started at SPERT, there were a lot of us. They hired quite a few of us, I think on the order of a dozen of us that were fresh out of school. Some with Bachelor’s degrees, some with Master’s degrees, in physics and engineering mostly. At that time, there were no nuclear engineering schools in the country that I knew of. They didn’t hire any nuclear engineers, that’s for sure. That field started later. Not much later, but it started a little bit later. The first school was in Tennessee, because I knew people who went to that school. After they graduated, then they went back to the school at Tennessee in nuclear engineering.

 I started out as a reactor operator on the SPERT-I core. It was a destructed core. They had done several tests on that reactor where they had taken it to lower and lower reactor periods. That means that the test was over faster. The shorter the period—the period is a number that is the number of e-folds that the power increases, and it was measured in milliseconds. They had done tests as short as five milliseconds before I got there, and they had done some damage to a core.

It was a plate-type core they were using. The core was uranium-aluminum fueled, and the plates were very thin. They were thin and wide. They had a thickness of 20 mils—a mil is a thousandth of an inch—so it was .020 inches thick aluminum, and then that thickness of uranium-aluminum. Then on the outside on each side, they had the 20-mil thickness aluminum. For the five-millisecond period test that they had already run, they had melted part of the central part of the core. This core was very small; it was about two feet high and about two feet square. Not very big.

It had four control rods and a central transient rod. The transient rod, for a SPERT-I D core I believe, was forced out. As I recollect, it was not just dropped out of the core. It was forced out of the core, I think pneumatically forced out. It could go out very rapidly, so you could get a fast transient.

The period of the transient was determined by how much excess reactivity you had in the core. The control rods came from the top, so they would bring the control rods out until they got critical. Then, they’d bring the transient rod in from the bottom to make them subcritical, but they’d keep the control rods at the critical location. Then knowing the worth of the control rods, they’d raise them up a delta, and that delta was how much excess reactivity they were going to put in the core when they blew out the transient rod. They’d be subcritical, but they’d have these control rods at a higher position than was critical. They’d blow the transient rod out, and the reactor would take off on a rapid transient.

They were preparing for the SPERT-I D core. I got to train on the SPERT-I D core, myself, and a couple other of the new hires. To me, it was all very interesting. In fact, I thought the people who knew the most about what was going on were the electronics technicians. There were a couple of electronics technicians who were doing the wiring. The core was a half-mile away from the control room, so we were operating a half-mile away from the actual reactor core. It was just a little hole in the ground backed by—I think steel, and I don’t know even think it was stainless, just steel. It had water in it, and it a core in it, and it had a tin shed over it. That was SPERT-I. It was not very impressive.

Having worked on machinery and worked on diesel-electric units as an electrician helper, I wasn’t too impressed with being a reactor operator. It seemed to me like it was like a glorified elevator operator. You had a lot more bells and whistles, but it wasn’t that complicated a thing to do, really, to operate a reactor or even to run a transient, I didn’t think.

I stayed in that job only three months and then got myself transferred. I let them know I was unhappy with that, and they were very good to try and fit you in where you wanted to be.

I got placed in an experimental group on the SPERT-I D core, still, which is good, because this was the most exciting thing that was going on at SPERT at the time. I got to work on the pre-test analysis. After the test was done, I worked on the post-test analysis and on the final report for the SPERT-I D core.

The SPERT-I D core, they did photograph. They photographed the SPERT-I D core from several angles. They took the roof off of the metal shed that was over the core. The core was at the underground level, so the best shots are looking right over the core. 

As you blow the transient rod out, the core gets hotter and hotter because the temperature is increasing very rapidly. What happens is, you get a molten fuel coolant interaction. We had aluminum, which melts at quite a low temperature, around 615 degrees Centigrade. A large portion of the core melted, and you got a molten fuel coolant interaction, which means: you break this aluminum up into fine particles, and the finer the particles, the more heat transfer you get. If you have large plates, you get heat transfer much slower than if you broke those plates up into tiny pieces because you have a much higher surface area. The higher the surface area you have, the more rapidly you can transfer the heat from the aluminum and the uranium-aluminum fuel to the water.

What really occurred then was a steam explosion. The molten fuel coolant interaction causes a steam explosion, and the water turns to steam and is blown out of the core. It took quite a bit of the core with it. There was one large camera that was over the core.

Then looking down into the core, the first thing you see when the core begins to come apart and the molten fuel coolant interaction begins, is that camera starts to raise up. The camera is being blown up, and the hardware over the top of the core is moving up. Then it blew the steam and water out of the core, and it took some fuel with it. It went like fifty feet in the air, way above the roof of the building. It actually bent the beams in the building, as it went up. It kind of looked like Old Faithful. If I can think of a simile, that’s the best one I can think of.

Prior to the SPERT-I D core, the SL-I accident had occurred about a year before. That’s why they really did the SPERT-I D core tests, to try and figure out what happened in SL-I.

The same sort of thing happened in SL-I. They believe an operator pulled a control rod out rapidly, and at that time, that particular core could go critical on one rod. Since that, they never made a core that that could occur in. The job they had to do was to connect the control rods to the control rod drives. They had to be taken loose, because they’d been working on SL-I. They believed that the operator was trying to get the control rod up to connect it, and he pulled it out too far. It went on a transient. It was almost completely closed at the top. It had some openings in it, but not very many.

The molten fuel coolant interaction that occurred in SL-I, the force was great enough that it caused a water hammer. When the steam explosion occurred, it pushed water up from above. It turned out the water level wasn’t full; it would have been better if it had been full. It was only partially full, but it was above the core. It made a water hammer. It pushed that water up with such force that when it hit the top of the reactor vessel, Vessel-I, it raised it completely up out of the ground clear to the ceiling of the building, because there were control rods sticking in the roof of the building. Then it fell back down. It was connected by big heavy pipes, the water pipes going through the sides of that vessel. It sheared them off, as SL-I went up.

They had SL-I up at the north end at the big hot cell up there, getting ready to examine it at the same time as we were doing the SPERT-I D core tests.

After the SPERT-I D core reporting was finished, then I worked on the nuclear design of a prototype power burst facility called the capsule driver core. This was a core that had oxide fuel in it. They were fuel rods with stainless steel cladding and uranium-oxide fuel inside, in a ceramic form.

Well, the capsule driver core was a kind of a prototype PBF [Power Burst Facility]. PBF in the center, it was made to test bundles of fuel rods, or single or some fuel rods. Around the center of core, it had a very heavy—for PBF, I think it was zircaloy—zircaloy in pile tube, which was about a half-inch thick. The purpose of that was to decouple what went on in the experiment from what went on in the core.

The difference between the capsule driver core and the PBF is that PBF had water flow through the capsule, like you have flow in a pressurized water reactor or a boiling water reactor. It also could be pressurized, so you could have conditions that simulated what actually went on in a nuclear reactor.

We did forty-seven experiments in that reactor over a period from about 1977 to 1985. We did experiments on accidents called power cooling mismatch accidents, on reactivity initiated accidents, on loss of coolant accidents. We were doing blow-down tests inside of that pressurized container with fuel in there, several years before LOFT [Loss of Fluid Test] ever did any tests.

I consider LOFT as a PBF-confirmatory test, because we did lots of coolant accident tests. We did a test for Canada where we did a transient experiment on their fuel, so that they could have an idea of how their fuel would behave to a transient. Then we did operational transient tests, another type of accident that can occur.

We did severe fuel damage tests. After TMI-II [Three-Mile Island] occurred, then we did tests on what we called severe fuel damage tests, where we had a very large bundle. It was either 5×5 with the corners removed, so that would have been 21 rods. I think that’s what it was. It could have been 6×6 with the corners, but I think it was 5×5 with the corners removed.

So we had a pretty large bundle of fuel. We did simulate a small break loss of coolant accident, which is what occurred in Three Mile Island. We did four such tests. We had two or three of those done before they ever took the lid off of Three Mile Island. Actually, a report was written by Doug Croucher, using the results we got from the power burst facility, to predict what Three Mile Island was going to look like. He was very close.

Our experiments showed that you were going to get loose debris in the top. You were going to get a ball of previously molten fuel, and it was going to move down. It was going to drain down in the accident. We simulated four of those severe fuel accident tests, before LOFT did one.

Kelly: Just give us a sense of how this whole project, the coming of the government to do this work, had an influence on the area, and on your life in particular. As you say, there was no nuclear engineering—

McCardell: Sure. When I was thirteen selling subscriptions to the Deseret News, they were doing construction at the site. Atomic City was a pretty large place. It was mostly trailer houses. We weren’t allowed on the Site ever, but we could drive by. We could go to Atomic City, and we sold subscriptions. These were mostly construction people, but there were a lot of them because there were a lot of reactors built on the desert. We knew that. Growing up, I knew that. I did have that association with people, who were building reactors at the Site, some of whom lived at what was then Atomic City. Two or three people live there now.

Atomic City was just a very small place. It had been like a midway stop between Blackfoot and Arco. It had been a service station and grocery store. When they started building reactors at the Site, it just expanded into a huge place, where people lived that worked at the Site and lived in trailer houses. There were many trailer houses there. I’m sure that there were over a thousand people living there, probably more like 1500 to 2000 while they were building reactors at the Site.

Then as people came who were going to work on those reactors, the size of that town just shrunk down to nothing, almost. They made the central location in Idaho Falls, and most of the people lived in Idaho Falls or Blackfoot. There were people who lived in Arco, who came, and then there were some of us who lived in Pocatello. I rode the bus from Pocatello for a year.

I met my second wife, Lynn, at the Site. She can tell you about that. She travelled from near Mackay to work at the site.

Kelly: How long a bus ride was that from Pocatello?

McCardell: From Pocatello, it was about an hour. About an hour ride out, and an hour ride back. Not much more than Idaho Falls, really. It might have been an hour and ten minutes. I caught the bus at the very last stop in Pocatello, and I was about the first one off. I made sure of that.  

The job was fun for me. It was that way for thirty years. It was fun to go to the Site, because it was exciting. The things we were doing were exciting. When I would go give a talk on what I was doing, I would know more about what I was talking about than anybody else in the world. You were right on the cutting edge. Made it very easy to give talks, that’s for sure. Because nobody was going to question you, because they didn’t know how.

It was very exciting and fun to go to work. One of the only jobs I’ve ever had that had been that way. Prior to that, my jobs were—well, it was fun teaching. I enjoyed teaching, when I was a graduate student. I spent a lot more hours at the Site than I had to, especially during PBF days, when we would be there for like a week getting ready to do the test before it was finally done, in preparation of doing the test. There were times I’d stay there for a week. I’d take my pickup camper out, and camp out there. Then later, they built bunkhouses for us at PBF.

But it was just a very exciting place to work, because we were doing things that had never been done before. When I first started out there, you could come up with an idea and lay out how you were doing to do the experiment to either prove or disprove that idea. And next week, do the experiment, the next week, write up the results. In a month’s time, you could start from an idea to a finished product, which in today’s environment, takes years and volumes to do anything like that. 

It was a really exciting time. We were given the freedom to do those sort of things, which was just an excellent environment. It was more like a university environment when I first started at the Site.

If it hadn’t been for the Site, I would have had to move to a large city to work. I wouldn’t have been able to stay in Idaho near my people.

Actually, my wife and I have our own little farm that we’ve built up over the years. The Site has made all that possible, that’s true. I could not have stayed in Idaho without the Site. I would have had to leave. My plans were to go to Texas A&M as a teaching assistant and work on my PhD. That was my plan, if I hadn’t have worked at the Site. That’s what I was going to do.

Heaven knows where I’d have ended up. My advisor ended up in Australia.

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