skip to main content
Home  /  Interviews  /  Marianne Walck

Marianne Walck

Marianne Walck

Deputy Laboratory Director for Science and Technology and Chief Research Officer at Idaho National Laboratory

By David Zierler, Director of the Caltech Heritage Project

May 18, 2022

DAVID ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It's Wednesday, May 18, 2022. I'm delighted to be here with Dr. Marianne Walck. Marianne, it's great to be with you. Thank you so much for joining me today.

MARIANNE WALCK: Thank you. Happy to be here.

ZIERLER: To start, would you please tell me your title and institutional affiliation?

WALCK: I am at the Idaho National Laboratory, INL, and I am the Deputy Laboratory Director for Science and Technology and Chief Research Officer.

ZIERLER: How long have you been in that role, and what are some of your major roles and responsibilities at INL?

WALCK: I've been here for almost three and a half years. I started in January of 2019. I am one of two deputy lab directors, and along with the lab director, we run the laboratory, so we have that internal role of organizational things. And in fact, today, we announced an organizational change, and those things are always fun. I also run our internal research and development program, which is called Laboratory Directive Research and Development. I run our program with the DOE Office of Science at the Laboratory. As you know, the DOE Office of Science is a $7-billion-a-year organization that funds a great variety of things, including some things at INL. And I am responsible for our overall laboratory technical strategy and for documenting that and our annual laboratory plan, which we have to submit to DOE, which just went in in April this year, then we'll be presenting it with DOE. And I represent the Laboratory in a variety of functions both internally and in the community, as well as in the national laboratory community. I'm a member of the National Laboratory Chief Research Officers group. I'm a former chair of that group, I was the chair in 2020, so I have a variety of things I do on an ad hoc basis across the entire national laboratory system with the chief research officers. Most national laboratories have a director who's in charge of the whole laboratory, and our laboratory's about 5,400 employees right now. And I believe we're the fifth-largest from an employee perspective. There are 17 labs. And most labs also have a deputy for management and a deputy for research. That's how I fit in.

ZIERLER: What are some of the most exciting science and technology endeavors happening at INL these days?

WALCK: We actually have, I think, a pretty good range of things we do at Idaho National Laboratory. We don't do everything. We're relatively well-focused for a national laboratory. We're an applied energy national laboratory. There are three of those. INL for nuclear, so we're sponsored by the Office of Nuclear Energy and DOE. There's also National Renewable Laboratory, or NRL, which does renewable technology, such as wind and solar, then the NETL, National Energy Technology Lab, which does fossil primarily, and now is focusing on carbon capture and sequestration with fossil as a potential clean energy source. We've got three applied energy labs, three national security labs, and one focused on environmental management, which is Savannah River. We fit into the ecosystem in the more applied energy area, focusing on nuclear, but we also focus on integrating nuclear and other energy technologies into things we're calling integrated energy systems right now that can produce both heat and electricity at the same time or orchestrated such that we could have a very flexible energy supply for both electricity and creating chemicals, desalinating water, all those types of things all within a geographical area. That's a focus we have, and I think it's very exciting because the type of thing we need to do for the future clean energy system to be able to meet flexibility demands and use our resources appropriately.

Right now, nuclear energy is usually produced by very large light-water reactor plants that are around the order of a gigawatt each. They're not very flexible. They're great for base-load power, but it's difficult to turn them on and off quickly. We use natural gas peaking plants for that in this country, so we need clean ways to peak power, and then we throw away a lot of energy through thermal heat. How can we use that? Those are the big-picture things we're trying to think about. From a nuclear perspective, the Laboratory is focused on advanced nuclear technologies. Right now, we are looking mostly at smaller reactors, either small light-water reactors, which are technologically similar to what we do with the big ones, or else micro-reactors or some other small modular reactor technologies that are not light-water. They used different types of fuels, but they have advantages in terms of inherent safety characteristics. They're much less complex, they typically do not operate at high pressures like light-water reactors do, and they have longer fuel cycles so that you do not need to refuel the reactor so frequently.

The big plants we use now have to be shut down every 18 months to two years to be refueled. And then, the smaller ones give you some flexibility in terms of potentially using them for load-following but also for different applications like remote cities or a big mine somewhere in a very uninhabited region that you're currently powering via diesel, places that you can't get infrastructure to easily, so we could potentially use these very small nuclear plants for those applications. The Department of Defense is very interested in them. We are trying to move those technologies forward in order to create the potential for nuclear energy as part of the national energy solutions in the future. That's a huge focus for our lab, integrated energy systems. The third thing we do that is very important is cybersecurity for control systems. This may sound a little different, but we've been doing this for a long time here at INL, and it's very important for all our energy systems to make sure that we've got the appropriate protections to keep us safe from cyber attack. Those are sort of the big three things we do at INL.

ZIERLER: A current events question. As Europe is scrambling for new energy supplies, given the war in Ukraine and the Russian embargo, what leadership role can INL and the United States play generally in demonstrating that civilian nuclear energy can and should be part of the equation, both from a global-warming perspective and from an international-security perspective?

WALCK: Yeah, I think the international security role of nuclear has been neglected. If we retreat from nuclear energy in this country–and we still have 93 operating reactors that produce almost 20% of our electricity and more than half of our carbon-free electricity–we lose our place at the table internationally. Russia and China are both eager to build additional nuclear power plants across the world, and we really want US technology, safety standards, fuel cycle standards, and nonproliferation standards to be part of that mix because it's all wrapped up together in terms of people's perceptions about nonproliferation. And the other thing, with different fuel cycles, you have the potential to use fuels that are much less attractive as far as proliferation potential. Current light-water reactor fuels do produce plutonium, so you have to very careful about how you deal with the spent fuel. How can we do this? We have to engage in the conversation, and I know that the US DOE right now has a big effort on trying to address the uranium shortage we could be facing due to the fact that we're not purchasing uranium from Russia right now, and typically about 20% of our uranium for our power reactors comes from Russia. That's not to mention the issues with European natural gas dependence on Russia and other things. We're working very hard right now with the Department of Energy to develop a strategy, and we have some experts from INL who are working with them on that strategy.

ZIERLER: To get a sense of where your portfolio fits in in terms of the overall national policy, in Washington, what are the federal agencies, the offices, or even the individuals you have direct interface with?

WALCK: All the people at the Office of Nuclear Energy. There's an assistant secretary who reports to the secretary of energy, who is Katie Huff, who was just confirmed. I have interaction with her and with various deputy assistant secretaries as well in her office. She reports up through what we call S4, the undersecretary for science and innovation, which used to be called the undersecretary for Science and Energy. That's Geri Richmond. She's from the University of Oregon, and she just started several months ago. I've interfaced with her and known her for a number of years. Then, from a defense perspective, the National Nuclear Security Administration is run by Jill Hruby, who I know very, very well from Sandia. She was my direct supervisor for about seven years. She is the S5 undersecretary for national nuclear security. I don't have a programmatic need to talk with Jill all the time, but I have access to her because she's a friend of mine. And we do a lot of work also with–and this is a bit of an oddity with the Department of Energy–an organization called Naval Reactors, which is a part of NNSA, National Nuclear Security Administration, NA30, but it is also associated very closely and part of the Department of Defense to some extent. It's interwoven.

And we run a facility called the Advanced Test Reactor out here at INL, which does thermal irradiation of the fuels that the Navy is considering for the submarines and aircraft carriers, so we at INL do have a big connection to NNSA through NA30. We also do some work for nonproliferation. Then, in the Office of Science, I don't know the newly confirmed head of the Office of Science personally, although she is, I think, a geobiologist, so an earth scientist. She must be good. But I do know the principal deputy associate director, Steve Binkley, and I also know Harriet Kung, who is a S3, the head of the Office of Science research programs very well also. I talk with them occasionally. It's mostly people in the Department of Energy. In my past, I worked with the Nuclear Regulatory Commission quite a bit, I worked locally with DTRA and a few other agencies, but I would say those contacts are sort of on the old side.

ZIERLER: At INL, what are some opportunities for collaboration, both with academia and private industry?

WALCK: We do a lot of both. We have a couple of academic collaborations, official ones, that are run out of my office. We have one with Idaho universities that the state of Idaho invests in. They want to have their universities working with Idaho National Laboratory in a symbiotic way. Idaho's a small state from a population perspective. We have about 1.8 million people. We've got three research universities, one national laboratory. I believe we're the sixth or seventh largest non-governmental employer in the state, and we're certainly the largest employer in Eastern Idaho as we're located in Idaho Falls. We have a consortium with the state schools, called the Center for Advanced Energy Studies, and we work very closely with them. We try to work on things like joint proposals for research funding and development of future employees for the national lab system and for high tech anywhere.

Then, we have another consortium we run with five universities across the nation that all have nuclear engineering programs and nuclear research reactors on their campuses, and we call that the National University Consortium, or NUC, which I think is sort of cutesy, but I didn't name it. We have a lot of collaborations with them. We do joint appointments, so we have faculty exchange and staff exchanging with faculty, we do joint research. Our internal research program, our LDRD program, allows us flexibility on funding universities, those types of things. There's quite a bit of academic collaboration. With regards to industry, DOE NE, Nuclear Energy, funds a number of programs that are very industry-focused with lab participation. We can put together proposals with industrial partners to the Department of Energy to be funded together. There's actually a mechanism for industry to come to a national laboratory and ask us to do work for them that we're uniquely qualified to do, so we can do that through cooperative research and development agreements or through projects where they just pay us to do R&D. And at INL, we have a number of really interesting and unique particularly nuclear facilities that aren't available elsewhere in the country.

ZIERLER: I can appreciate at Sandia where a seismology and geophysics background would be relevant in terms of nuclear weapons testing and explosions. Is there also a place for this course of study, analysis, at INL?

WALCK: Yeah. Although, there is not a focus on seismology. We have a few seismologists on staff here. I'm a seismologist, and I think I got this job because I have a long career of leadership in the national lab system. Although, the guy who hired me, Mark Peters, by the way, was a post-doc at Caltech. I can't remember who he worked with, but he's a geochemist. I'm sure he appreciated the glories of being an earth scientist when looking at who to hire for this job. But we do have seismic hazard in our area. Idaho Falls is on the Snake River Plain, flood basalts from a Yellowstone hotspot, etc. We have a network of seismometers out across the site. We have a lot of government land, 890 square miles of it, that starts about half an hour west of Idaho Falls. We call it The Site. And we have a network of both micro-earthquake-type seismometers, but also strong-motion accelerometers, that we monitor, and of course, we record regional, local, and teleseismic seismicity with those networks. We don't do a lot of programmatic stuff in seismology. We also have a program in geothermal. We're a great location for geothermal, and we've worked on geothermal projects for many years at INL. I would say we're not at a high point on that now, but given the potential for geothermal, especially with enhanced geothermal systems where you actively fracture the rock below the surface and pump water into it to extract hot water, we can have the potential to do more with geothermal as a renewable and clean energy source, so we're certainly trying to think about how we can best do that at INL. There are other labs that do geothermal as well, of course.

ZIERLER: This has been a great tour of what's going on currently. Let's go back now to the 1970s. As an undergraduate, were you specifically interested at Hope College in seismology and geophysics? Was that on your radar even that early?

WALCK: It was. Actually, not when I started college. When I first started, which was in fall of 1974, I took–Hope is a liberal arts college, and at that time, it had a really substantial core curriculum, so I took a lot of that stuff, and I also enjoyed taking German in high school, so I took some German classes there, too. But I took chemistry, physics, and math, calculus. We didn't have calculus at my high school, so I had to start with Calc 1. Then, after about a semester, I realized that chemistry was not for me. I had a great high school chemistry teacher, and I thought I liked chemistry, but when I took it in college, even though I had a good professor, I realized it wasn't really my thing. But I still liked physics. I thought, "Hey, I've always liked volcanoes, and rocks, and stuff. Let's take a geology class." I didn't do that until, I think, I was a sophomore, when I took Intro to Geology. I started it late, let's put it that way. I took it, and I thought, "Hey, this is fun. I really like this, but it's pretty descriptive. I want to combine it with my physics." And it turned out that Hope already had a composite major for geology and physics they'd developed for a couple previous students. It was described in the catalog and was an official major. That's what I majored in, geology and physics as a composite. Turned out, I was one course short of a double major, and it was the chemistry class I didn't take. But yes, I was always interested in college. And in seismology in particular.

ZIERLER: Were there professors, or did somebody give you a boost of confidence that a place like Caltech was in range for graduate school?

WALCK: I do remember I had a particular geology professor–I was of the generation where there were a lot of women who didn't have long careers. I remember telling this guy, I think I was a junior in college, I thought I'd go to grad school, get a master's, and probably eventually get married and have children. By the way, I did get married and have children. But he said, "Why don't you get a PhD?" And I said, "I've never thought about getting a PhD." And that's interesting because I did have relatives who have PhDs. My dad was a first-generation college student in his family, but my mother's family is very well-educated, and she had a brother who was a chemistry professor at a small college, so I was familiar with PhDs, but it hadn't occurred to me to do it. Once he said that, I was like, "Hm, okay." Then, I don't know if they really encouraged me to try to apply to Caltech or not, but Caltech was, like, the place to go for seismology, and I was interested in seismology, so I thought I would give it a shot. I also applied for an NSF graduate fellowship and miraculously was awarded one of those. I got lucky on that. But they were encouraging, certainly, although I do remember one of the physics professors telling me that I wasn't going to be at little Hope College when I went to Caltech, and I better be ready for the big world.

ZIERLER: When you got to Caltech, first of all, at the Seismo Lab, were there other women graduate students? Were you part of that sort of inaugural class?

WALCK: There were graduate students who were women there ahead of me. One had just graduated before I arrived, and I've never actually met her. Her name was Sue Raikes, and she was British. She went back to Britain, I believe, after she graduated. I have never actually encountered her. There were two women graduate students in the Seismo Lab lab, and there was one geology student, Joanna Vizgirda, who worked with Tom Ahrens, and I believe she was officially a geology student, although I'm not 100% sure, but she's not a seismologist. But we had Pat Scott and Hsui-Lin Liu, who were both in the class right before me. And then, there were two more who came in the class after me, Holly Eissler and Victoria LeFevre. When I arrived, there were three, me, Hsui-Lin, and Pat.

ZIERLER: When you got to the Seismo Lab, what were your impressions?

WALCK: I was completely intimidated. Caltech is a very challenging place, and I came from this little college, and a lot of the people came from pretty impressive schools. And everybody questioned everything that you did. Let's take a look at some of my classmates. There were six of us originally, then one of them left, a guy from Venezuela, after the first year. But my four classmates were Terry Wallace, Thorne Lay, Mario Vassiliou, and Tom Hearn. Terry, of course, had a long career at University of Arizona and eventually became the director of Los Alamos for a year or so. And Thorne is an eminent seismologist at Santa Cruz, and Tom Hearn is still at New Mexico State as a professor. Mario went into industry. It's a pretty intimidating group.

ZIERLER: Did you have a good idea of what you wanted to focus on when you got to the Seismo Lab? Were you wide open in terms of topics and even professors to connect with?

WALCK: I was wide open. I think one of the great things about the Seismo Lab is that they don't force you to pick an advisor before you show up. And I understand from my recent visit to Caltech back in January that they still have this open-funding model, where you can do a variety of things with different professors. I think that's absolutely fabulous. It was a terrific opportunity. I certainly had to focus on my classwork to begin with. I was behind in math compared to a lot of people. Honestly, Hope College did not have some of the classes I should've had in math, so I had to try to pick it up pretty quickly, and that was a struggle for me. I had some self-confidence issues at the beginning, and it took me a while.

There was a female post-doc there, ChristinePowell, who is still working, I believe, and she got me started on a project that I used for one of my propositions for my orals, my first and biggest one. Then, after she left, I sort of transitioned over to Bernard Minster, who then left and went down to SAIC, I believe, and later UC San Diego, and then Don Anderson took me on. But it was sort of an interesting relationship. I didn't start with Don Anderson because I wanted to do Don Anderson stuff, I sort of evolved into it. I did an orals project with Hiroo Kanamori, and my third was with Don. We had to do three at that time. It was an evolution, just trying to get to know people and figure out what I wanted to do. But I was initially interested in earth-structure seismology, and that's what I stayed in.

ZIERLER: Once you got comfortable at the lab and got the lay of the land, what were some of the big debates in the late 70s, early 80s? This is after plate tectonics. What were the professors really excited about at that point?

WALCK: We were really doing synthetic seismograms for the first time, and that was really evolving in terms of doing high-fidelity source modeling.

ZIERLER: What does that mean, synthetic seismograms?

WALCK: Creating a seismogram from first principles based on earth structure with a computer. Don Helmberger was huge in this. Cagniard-De Hoop. And then, Dave Harkrider did more of the surface-wave stuff and matrices. Don Anderson was doing normal modes. You could do this at different wavelengths, so body waves, surface waves, but just trying to mimic what the earth had shown you from first principles and saying, "If the earth model is this, this is what my seismograms ought to look like." I still remember Terry Wallace putting together something that I thought looked not that great, but he was very excited about it because it was a strong-motion synthetic. Now, it's quite routine to create models of entire wave fields, and we have magnificent computing power.

When I got to Caltech, they had just bought the Prime mini-computer. My spouse, who graduated from Caltech a year before me, had to use decks of cards and go over to the computing center at Caltech. I didn't have to do that. We had the Prime right there in the building, but we had to go to the computer room to sit down at the computer terminal. Later on, each graduate student office got its own terminal. That was great. I didn't even see a PC until I got to Sandia. It was a different world for computing then. And of course, the fidelity at which we could model seismic wave fields was quite different back then. That's what everybody was excited about. And there were many other things, too, but that's what comes to mind.

ZIERLER: When did you connect with Robert Clayton?

WALCK: Well, when he came to Caltech. I was a fourth-year student. We were already well along, and I'd started doing work on upper-mantle velocities using the Caltech array, but not in the wave field sense. Profiles, profile modeling. I was using WKBJ methods. Rob came the fall when I was a fourth-year student, and I took his class, and we started doing some work together.

ZIERLER: What was his focus at that point? What brought him to Caltech?

WALCK: I think he was more of an exploration seismologist at Stanford, so I think Caltech was interested in broadening their faculty expertise in that area. But what was interesting to me was, once Rob got to Caltech, he started doing earthquakes. Not oil field seismology. It's just that much fun.

ZIERLER: Did you do field work at all as a graduate student?

WALCK: I really didn't. A lot of the graduate students did, but I never really got into that. I would have to check this, but if I was not the first, I was one of the first students whose data for a thesis was all digital. It was very common back in those days to do global network data that was on microfiche, or in some cases, on pieces of paper, that you would have to put at a digitizer and digitize it. I know my husband did that for his thesis, and he was a surface wave guy. But they would actually have to sit there, pick points, and enter it into a computer. The data I used was all from the Southern California Network, and it was all originally digital, which made it easier. It was also already there. I didn't go aftershock-chasing. People who did that, at that time, used smoke paper recorders, where you actually would take a flame and put a layer of smoke, basically, on a piece of paper, and then there would be a stylus that would scratch out your seismogram for you to record aftershocks.

ZIERLER: In analyzing all of this data coming in, what were some of the theories that might've served as intellectual guideposts?

WALCK: I looked at upper-mantle discontinuities. We were looking at differences between the 400-kilometer discontinuity, the 660, 670, 390, 410. Then, of course, Don Anderson was big into Lehmann discontinuity or whether there was a big global discontinuity around 200. That was a big question. I didn't really look at that depth range. For my thesis, I was mostly looking at the Gulf of California and Cascadia. I was looking at the 400 and the 670, then connecting it to the petrology, so what causes these P-wave discontinuities in the upper mantle from a petrologic perspective. Is it chemical changes, phase changes? What happens to make that happen? And trying to understand the seismic wave speeds down there would perhaps provide you with some constraints on what was happening from a composition and pressure perspective, composition perspective in particular.

ZIERLER: Were Clayton and Anderson co-advisors on your thesis?

WALCK: Officially, Don was my thesis advisor. I would say I worked more with Rob the last two years there. But that's the glory of the Seismo Lab, you could do that.

ZIERLER: Is that because what you were doing was more in alignment with what he was doing at that point?

WALCK: Yeah, I think. And then, I would go and talk to Don Helmberger about the modeling, the other graduate students. Steve Grand was doing a lot with S-wave upper-mantle modeling, and he developed some really good, important shear-wave models for tectonically active areas that served as a base or counterpoint to the P-wave models I was using for similar areas. I was very lucky because I got some really good data from the Southern California Network that were unusually good for that time period. Sometimes seismology is being lucky. But I think Don was more into the rock physics stuff at that point. People evolve over their careers, and he had such an illustrious career. He wasn't afraid of controversy, he would go into these areas, and some people would say, "What does he know about that?" But he could do that. And from a seismic perspective, I think Rob was more aligned with what I was doing. But I sort of was out on my own a little bit, too. And you did that once you were a fourth- or fifth-year student.

ZIERLER: Speaking of controversy, did you get involved at all in some of the debates around earthquake prediction?

WALCK: I didn't. They were still talking about it when I was there, but that was more before I arrived. I knew there were some guys going around–one of my co-students, Jeff Given, went around every month taking gravity measurements. They were doing this sort of gravity-over-time stuff to see if that was illuminating in any way. Of course, radon was big at that time. I didn't do that myself.

ZIERLER: Was JPL an asset for you in graduate school?

WALCK: I wouldn't say so for me personally. I think JPL is an amazing institution, and I got to go over there once or twice. A lot of the planetary science students were over there all the time. I didn't really get involved with anything at JPL.

ZIERLER: What would you say some of your contributions or conclusions were in your thesis?

WALCK: It was the first paper I wrote about a little-bit-shallower upper mantle underneath Southern California. It was more about illuminating some of the lateral velocity variations around the Transverse Ranges, and I came to some conclusions that were a little different from what previous people had done using an interesting technique called relative array diagrams from Chris Powell. She was the one who first showed me how to do that. With regards to the upper-mantle structure and profile, I had data that probed essentially the upper mantle beneath the Gulf of California as an active spreading center. That's the paper I've written that has actually been cited a number of times, and it had a very large gradient above the 400-kilometer discontinuity, and I was able to see some fairly fine structure on the 660. And I think the 660 has held up pretty well as the right depth, although I've lost track over the last 20 years what people are thinking these days. And then, I did some cool stuff with Rob on wave-field continuation for the upper mantle, some different ways of looking at these seismic profile data. But it's some good data. I've been pleased that some of my data profiles have been included in some textbooks, which was sort of fun. And then, I did a comparison of the Gulf of California with the Cascadia Zone, and it was a different gradient above the 400. Just some basic knowledge, which I think has held up reasonably well, about the upper-mantle structure.

ZIERLER: By the time you defended, were you looking at industry, academia, and national labs?

WALCK: No, I had decided partway through graduate school that academia wasn't for me. I looked at how hard these guys worked, and I honestly didn't think that was me. I didn't know myself them, but I found out later that management and leadership in the scientific enterprise was something I had more of a distinguishing characteristic and ability for, whereas I think I was an okay scientist. I'm not as brilliant as many of the people who went to Caltech, just being honest. I could tell that. I didn't think academia would be right to do with my life. I looked in industry and at national labs. There was a guy named John Rundle who worked at Sandia who was a visiting scholar at Caltech, so I knew about Sandia from him. And then, my husband got a job at Sandia, so then I became very interested in getting a job at Sandia as well. He graduated in '83, I graduated in '84. I applied to Sandia as well as several oil companies and a post-doc position, and I got several job offers, but I got the one at Sandia, so that was where I was going to go so I could hang out with Eric, so there you have it.

ZIERLER: During the Cold War, was nuclear security, nuclear verification a really important part of Sandia's portfolio?

WALCK: Absolutely. Actually, Sandia had about three different areas where they used geophysicists at that time, always in the treaty verification organization directly, another was in energy organizations, so geothermal, magma, energy things, and I wrote some papers in that area. Also wrote some papers in nonproliferation. But then, we also had a research geophysics group that was supposed to be more fundamental research, and that's the one I joined. When my husband went, he started with more of the applied energy area, then he migrated over to nonproliferation, where he stayed the rest of his career. He became a distinguished staff member at Sandia and retired in 2016. But then, I went into management fairly early. But we were still doing nuclear testing out at the Nevada test site at that point. Sandia ran a network that recorded the ground motions from the nuclear tests at the 10 to 50 kilometer ranges, so pretty close, but not right on top of it, although they did some close-in instrumentation as well. Then, there were the global networks for nonproliferation that Sandia, Los Alamos, and Livermore all had a hand in analyzing the data and understanding the verification issues.

ZIERLER: What was your first job at Sandia?

WALCK: I was a member of the technical staff in the geophysics department. I got to sort of figure out what I wanted to work on. There were some funding constraints, but I had a project funded by the Magma Energy Program at the time, which is sort of an offshoot of geothermal. Could you put a heat exchanger into a body of magma and extract heat? There were a couple problems. One, getting the heat out. Then, having your heat exchanger survive. Another is finding the magma. By that point, I started working on some tomography stuff with Rob Clayton, so I would go to Caltech periodically to work with Rob on that. And we did a paper on Coso on tomography and looking for low-velocity regions that could be magma. That was fun. But that was only part of what I did.

The other part when I first started was looking at ground-motion data at the test site from a certain set of explosions recorded at a place called Jackass Flats and had very unusual amplifications, and there was about 50 kilometers' distance. I was trying to figure out why this amplification occurred. It was on a very, very small geographic area. They had put a little array of ground-motion instruments out there to try to map out this anomaly, and I did some work on that. I also looked at ground motions from nuclear explosions recorded at Yucca Mountain, Nevada because they were thinking about the potential repository for spent commercial nuclear fuel there. At that point, they were still setting off explosions at NTS, so the question was, how much did that shake the mountain? The answer was, not a heck of a lot.

ZIERLER: Did any of this initial work require a clearance? Was it classified?

WALCK: Everybody at Sandia had to get a clearance, so I got one. I don't think my first work required it.

ZIERLER: When did you start to get more into the national security side of things?

WALCK: Within a year or two, I started working on some of the treaty verification things, and at that point, they had the treaty verification all in a controlled area. They didn't all need to be in there, but it was just easier. And we did things like Hard & Deeply (HDB7) buried targets over the years, ground-penetrating weapons requiring knowledge of geoscience, but a lot of the treaty verification research itself is not classified. But I've used my clearances over the years on a variety of topics, but I never actually worked directly on nuclear weapon design or engineering.

ZIERLER: With the verification, did you work directly with either the State Department or the ACDA?

WALCK: No, this was all DOE. NA22 is the office of research and development for the nuclear nonproliferation part of it. They've had a very longstanding program with the three national security labs, Sandia, Los Alamos, and Livermore on discrimination of earthquakes from explosions using various wavelengths at various distances for various sizes of things. After I went into management, I got out of doing the actual R&D in that area, and some things about it were certainly classified. If North Korea sets off a test, we probably don't want to tell what we know about that to other people, but Sandia and the other labs certainly had people looking at those very carefully and trying to see what they could determine. Then, some of that would be publishable, and some of it wouldn't be.

ZIERLER: Between the R&D and verification, where was there overlap with Los Alamos, and where did Sandia have its own unique portfolio?

WALCK: Sandia was typically focusing on what they called automated data processing. I think Los Alamos had a particular geographic region, Livermore had a different one. My husband knows more about this stuff than me. But Sandia was more in the automated data processing systems. They built one in the 90s for AFTAC out of Patrick Air Force Base in Florida. Eric was traveling back and forth there all the time when we had our first child, so that was interesting. But that was Sandia-led, the system to bring in the data and do processing of the data for identifying events and those types of things.

ZIERLER: How long after you joined Sandia would you say you were already on a management and leadership track?

WALCK: It's hard to say, but I have to admit that within the first week I was there when I sat down with my supervisor, he asked me if I would consider going into management. I think part of that was maybe my experience at Caltech, and that I ran things, like the softball team, ski trips, and stuff. I don't know, certain people like to do that. But he asked me about that early in my career, and I became the manager of the group I was in after six years, which is pretty early for somebody to go from staff to management. Because that same guy left the group at that point. He was actually a mechanical engineer. I thought it would be good if we had a geophysicist running the geophysics group.

ZIERLER: Moving into the 1990s, how did the end of the Cold War change things at Sandia?

WALCK: Quite a bit. We had a lot of budgetary uncertainties, I would say, and no new nuclear weapons programs at the time. There was a bit of a dearth in hiring. That has propagated its way through the workforce as we've gone on. Of course, now, people who were hired at that point are sort of in the prime of their upper-level careers. But I'd say it really affected our ability to bring in new talent, and our emphases changed. At that point, a lot of the labs more aggressively pursued things they hadn't done before because they didn't have as much support from the weapons programs. It was more going after funding from various parts of DOE in order to maintain programs and employment for researchers. We broadened quite a bit.

ZIERLER: At what point did Sandia start to get involved in climate and sustainability issues?

WALCK: I'm not sure I can give you a date on that. I believe that we didn't actually form a climate program maybe until 2010. I became a center director at Sandia in 2009, but I was running the Nuclear Energy and Global Security Center. But I believe Rick Stulen, who was at Sandia, started the climate program. It was either 2009 or 2010, but it was nascent at that point. But these are the big changes in the national labs. First, you had the weapons focus and national security focus. And that's all it was in the old days. Then, the energy crisis in the 70s, so everybody started doing energy. Now, the shift towards climate, if you look at it over a several-decades time scale.

ZIERLER: Another big change, of course, September 11 and the Wen Ho Lee scandal at Los Alamos. How did the security environment change at Sandia?

WALCK: Certainly, 9/11 was huge, and we started working with DHS and a lot of security things. In terms of the operational security environment, Sandia always had good operational security. The big things I remember were when cell phones and Bluetooth devices started coming in, then there was a lot more angst about the ability of somebody to screw up on your security because you couldn't take a cell phone into a limited area, and Sandia was almost entirely a limited area. Turned out that the building I worked in was not. It was what's called a property protection area, so I could have my cell phone there, but if I took my cell phone into the limited area, which there was nothing to stop me from but a turnstile, and you use your badge and a pin to get in there, I would then have had to report that to security and possibly be given some sort of violation or infraction. Those were big changes. There was definitely an increase in the amount of work we did in homeland security that required high security. I wasn't typically incredibly involved in all that, but our organization that did that kind of work got a lot bigger after 9/11.

ZIERLER: What was some of the advisory work you did in Washington and around the country that was important to you personally but also mutually benefitted the national lab system?

WALCK: I think my advisory work started a little bit more recently, within the last 10 to 15 years, in terms of being on panels of various types. I've been on a lot of review boards for–I guess with LBL, I probably started back in 2000, so maybe the last 20 years. I've tried to primarily help other national laboratories with their earth science programs, reviewing the strategy. They always ask you to review the quality of the research. Typically, I think the quality of the research is very good. It's more about how you attract, retain, mentor staff, what you're working on, if what you say you're focusing on makes sense within the DOE ecosystem, those types of things. I got to know a lot of people more across the laboratory system around mid-2010's, when we started doing some laboratory system initiatives around earth science that I was lucky enough to co-lead with Susan Hubbard, who was then at LBNL and is now at Oak Ridge. She has the same job I have here at INL but at Oak Ridge. In 2014 we started a cross-laboratory initiative with the Department of Energy on subsurface science, which was a great tool to really get to know the earth science community across the national laboratory system and try to think about strategic directions for the future, see how much we could convince DOE to see the wisdom in looking at the big things.

The issue there was trying to develop funding streams from the Department of Energy. Because of the way they were funded, it was a tough row to hoe. But I think there were a lot of positives that came out of that, and I made a lot of positive relationships. Now, I'm on various boards. I'm on the Texas A&M Energy Institute board. When I was in Sandia in 2015, I got the opportunity to go out and lead the Sandia, California site, which at the time had 1,300 people. It's bigger now. But in that role, I got to be on the board of directors for the California Council of Science and Technology, which is sort of like AAAS but for California. It's pretty cool. And I enjoyed that. Also, the Bay Area Innovation Board. All of those things give you insights into what other people are doing in the science community and give you ideas that you can hopefully take back to your facility to harvest the best of those and try to implement.

ZIERLER: What was your most recent job at Sandia?

WALCK: That was my most recent job. The title was vice president for the California laboratory. I was also the vice president for the energy and climate program Sandia had at the time, and that was from 2015 to 2017.

ZIERLER: That was dual-hatted or one role with two responsibilities?

WALCK: Every leader at Sandia had a program job and a line job. My line job was the California laboratory, so I lived in Livermore, California for that, and my program role was for energy and climate, which was the smallest program at Sandia, but even so, it was $230 million a year. And most of the work for that program occurred in Albuquerque, so I was back and forth between there and California all the time. In that role, I got to interface with a very wide variety of people in the Department of Energy because Sandia did work for EERE, Energy Efficiency, Renewable Energy, we did work for nuclear energy, we did work for fossil. Our Office of Science work at Sandia was in that program. Any work we did with climate was in that program. It was a very broad-based program. A lot of fun.

ZIERLER: Tell me about the opportunity at INL and why that was attractive to you at that point.

WALCK: Well, I left Sandia because of a contract change. Every national laboratory has a contract, and certain people on the contract are named as key personnel. At Sandia, the vice presidents were all key personnel. NNSA decided to re-bid our contract in 2015. Our lab director, Jill Hruby, now the NNSA administrator, asked the entire leadership to bid with her with Lockheed Martin. We put together what we considered to be a really good package, and we submitted it. In December of 2016, we found out that NNSA had chosen not to renew our contract, and they were going to go to Honeywell. That meant I was going to retire or leave the laboratory in May of 2017. I was 60 years old at the time, and the next several months were very busy with all these transition activities. I thought about whether I wanted to try to take a job or not. I looked around at some volunteer opportunities, and I finally decided to retire and just do a few of these boards and activities. I did a little consulting for Los Alamos after I retired, and moved back to Albuquerque. We'd never sold the house, so we moved back in. Went hiking, played my violin, all that sort of stuff. But after a while, it just wasn't…

ZIERLER: You weren't ready yet.

WALCK: I wasn't ready. I didn't get to retire on my own terms. A friend of mine from Sandia, California, who had then gone to work at PNNL, alerted me to this job that I now have, which was very different from my job at Sandia. My job at Sandia has been retitled as associate lab director. It's a program and a line job. In some labs, it's only line, in some, it's program, in some, it's both. Here at INL, it's pretty much both for our ALDs. But that was a big, huge line. Lots of people, lots of program responsibilities. The DLD job for the deputy director and the CRO at INL has got a very small group of people that works with me, and I work on things that are a little bit more global with respect to the laboratory and more general science. And INL is a lab that has had a lot of changes over the years in their mission, and they have had a huge focus on demonstration and very applied stuff, and less on more fundamental science. The Laboratory leadership, Director Mark Peters, really wanted to keep working on developing our fundamental science base, and in 2018 he had to replace his deputy lab director who was leaving the lab.

INL is run by an LLC headed by the Battelle Memorial Institute, which bid on the Los Alamos contract and won. Battelle had to put together a bid team, and the previous INL deputy director for science was on that bid team, so he was obligated, when they won that bid, to go work at Los Alamos, and he did. That opened up the job that I have. When I heard about it, they had this need to develop our research excellence for the laboratory to a level that it had not been at previously. I thought, "Maybe I can help this lab." And it's in a part of the country I've never lived in, and I thought it would be fun. We're an hour and a half from Jackson Hole. That's not bad. I can get to Yellowstone in two hours, I can get to Sun Valley in two and a half hours, if I drive fast. Salt Lake in three hours. It's a nice location. My husband was interested in going north, and my kids were all grown.

ZIERLER: An adventure.

WALCK: Right. An adventure to finish my career out.

ZIERLER: To bring our story right up to the present, what are you currently working on? What are some of the key projects in your portfolio?

WALCK: Let's go back to our LDRD program, Laboratory Directed Research and Development. You're allowed to tax your incoming funds to create a pool of indirect money to do research under this program. All the contractor-run labs, the 16 of them, do this at varying levels. INL has always had a very small program. When I was at Sandia, the LDRD program was $160 million a year, and I know it's significantly larger than that now. When I came to INL, its program was $27 million a year, and it only represented about 2% of the annual budget of INL. What we've been doing very mindfully over the last three years I've been here is improving the management and the focus of the program as well as growing it. This year, we're at $40 million, and next year, we're going to be at $47 million. We have to work that with DOE on the size. And I knew a lot about LDRD from my time at Sandia and how to run an LDRD program, even though I'd never been in charge of Sandia's. That's one thing that we do.

My office also develops our Annual Laboratory Plan, which is a major strategy deliverable for DOE. Another thing we're working on right now is something we're calling a research culture initiative to try to take our research community to the next level.. We have really grown the number of PhD scientists we have at INL, which was not that large. When I arrived, we only had on the order of 30 post-doc associates at INL. We're now up to 100, so I've been working on that. Many of the labs have many more than that. A couple of the labs have 500 or so, so we're still a relatively limited post-doc program, but it's important to help us get new research blood into the Laboratory and to bring in new ideas from elsewhere. It's just a win-win. If you have a good post-doc program, and we provide good experiences for them, we can hire some of them, and the ones we don't hire, if they had a good experience, they'll be an advocate for our laboratory and continue to work with us, say, from a university where they're a professor. Now, we're working on more general concepts of research excellence, like how much of our work we can publish. Some of the national laboratories have a reputation for not getting their work out into the greater community, and I would say that INL can do better in that realm.

We're working on that and just attracting and retaining a diverse workforce. I do work quite a bit on diversity, particularly gender diversity. I am the top female in the Laboratory from a technical perspective or probably any perspective, so I have a responsibility as a role model. I go out and do things, like last Friday, we had an event we call My Amazing Future, which was about 300 or so eighth grade girls from Eastern Idaho who came in, and I did a little keynote for them and participated in a mentor session. I do things like that as well. But the big thing we're working on is really research excellence. How do we take INL to the next level? It got started before I got here. There was no question about it. But what I've been trying to do is to mature those programs and make them really well-integrated into the Laboratory so that everybody understands the importance of research to our community. And I work with our university partners on that a lot, too.

ZIERLER: Now that we've worked right up to the present, for the last part of our talk, a few retrospective questions, then we'll end looking to the future. Obviously, you've moved away from geophysics in the course of your career, but I wonder if you can reflect on some of the things you learned at the Seismo Lab, collaboration, leadership, approach to the science, that have stayed with you and served you so well in your career?

WALCK: I'm going to be maybe a little bit out on the edge here, but I think if you look in the national laboratory system, you will see an over-representation of earth scientists in their leadership. I haven't done a statistical study on this, but even when I was at Sandia, which might've had 100 or so earth scientists, we always had a few in very upper management. Why is that? And I mentioned my friend Susan Hubbard, a geophysicist, who's the CRO at Oak Ridge. Mark Peters was the lab director here, he's a geochemist. Everywhere you look, there's some connection to earth science. My view is that it's the inherent interdisciplinarity of earth science that helps people think broader, systems thinking, and enables people to have a leg-up in leadership. I think that's very important. I also got a lot of help at Sandia from a lot of really good leadership programs that helped develop skills. I think it also helped that I like working with people and always have. I wouldn't have run the Seismo Lab softball team if I didn't enjoy doing that. Maybe I enjoy telling people what to do, I don't know.

I had to do a career story talk when I was the vice president at Sandia few times, and I always showed this picture of the Seismo Lab softball team because when I was there. We were just starting to get students from China. They came, and they'd never played softball or baseball. They had no idea how to do it, but they all wanted to play, to be part of the team. And we played in the Caltech C-league, which was the lowest one at the time. They would let us play 10 people on the field, but everybody batted. When I first got there, we were called the Strike-Slips, but after that, we were called the Tremors, and that was because we had a little bit of a schism after a while. Some of the better players, led by Terry Wallace, wanted to go up and play in the Caltech A-league, which was fast-pitch. But he took some of the good people up, and I think that might be when the name-change happened. But I was running this team, and we had these people who had a wide range of skill. And I would have to say in the skill range, I personally was probably in the bottom third. We had a wide range of skill, and every inning, you could put different people on the field, and you went through your batting order.

Before every game, you had to put together a batting order, and you had to decide, "I've got five people who are really never going to get a hit here. Do I disperse them in the batting order or put them all in the same place and hope we can get through this to the people who can actually get on base?" And where do you put the people who have never touched a softball in their lives and couldn't catch one to save their lives? Usually, you put them in short field and hoped the center-fielder could get over there and help them. That was an easy fix. But I felt that was a good training for management and leadership because I had to get people to go along with me. Of course, there were several types of people. There were people who really wanted to win, there were people who were there to drink beer, and then there were people who sort of wanted to win and help you figure out how to win. You had to work that, work with people, and get them to figure out that what you were proposing might be okay, then get them to do it. Occasionally, we won some games. I honestly don't think we won a lot, but it was still fun. I enjoyed it. I think there were a lot of opportunities in those types of activities to learn how to be a leader.

ZIERLER: Looking over the course of your career at all the ways you've worked to advance the national interests, nuclear security, climate change, diversity in the field, what are you most proud of, and where do you think you've made the biggest impact?

WALCK: I hadn't really thought about that. Scientifically, I didn't have a particularly long research career, so I think probably one of the things I'm most proud of is being able to elevate earth science at Sandia. I was able to convince Sandia upper management when I was sort of a mid-upper-level manager to create what was called a research foundation for earth sciences, which hadn't previously existed there, which brought some attention, funding, and legitimacy to the importance of earth science to the national laboratory system. I think some of the work Susan Hubbard and I did with our DOE subsurface initiative was also impactful across the national lab system in building community and recognition of what earth scientists can do and how important they can be for DOE. Because there are earth scientists at well over two-thirds of the laboratories, and they're always there for a reason. Pretty much all the labs need them for something, but it's never the prime thing.

We don't have an earth science lab. The NETL would be the closest thing we have to that, and they don't have a large research staff. Trying to help people understand the importance of earth science and of course, climate has helped with that a lot. But a lot of the climate stuff is atmospheric, and I'm always thinking solid earth, so you'll have to forgive me for that. But I think that was impactful, and I think I've had an impact on INL in terms of identifying that some of the processes we were doing a few years ago that weren't of very good quality. Somebody has to call them out on that stuff. And if you want to provide critical commentary on something, what better place to be trained at than Caltech? I have a reputation here at INL for being direct. I've been told many times. But I think being direct has helped the research environment here and the research quality of what we're putting out right now, which I think is better than it's probably ever been, and I am proud of that.

ZIERLER: Finally, last question, looking to the future, have you topped out in your career, or is there one more job ahead of this one?

WALCK: There are no more jobs. I'm going to retire in a couple years. After Mark Peters left, I thought for a very short period of time about whether or not I wanted to apply for the lab director job here. I decided not to, and I'm very happy I decided not to. Lab director jobs are very stressful. I think this is the right job for me, and I'm always happy to the try to continue to have some impact on the national DOE labs scene through the chief research offices, and I think I can continue to do that through the next couple of years and hopefully be a mentor for people, and hopefully, a role model, if I can be, for female scientists. One thing I've been a little bit discouraged about, I would have to say, is the low numbers and the research environment for young women scientists, which hasn't changed as much as I would've thought it would've changed in forty years. I think that's probably more true in areas like engineering and geophysics compared with something like geology, geochemistry, geobiology, or some of the life sciences, where we're much closer to parity in numbers, but we're still pretty low in some areas. And I think people are still facing some of the same issues –the overt discrimination things, I believe, have largely abated, but there are a lot of subtle things that still go on.

ZIERLER: Marianne, this has been a terrific conversation. I'm so glad we were able to do this. I'd like to thank you so much.

WALCK: Thank you very much. It's always fun to reminisce.