The Sound of Science

TCR: Printing the future of nuclear

The Sound of Science - TCR: Printing the future of nuclear

Since 1943, Oak Ridge National Laboratory has built 13 nuclear reactors — now it's preparing for its 14th, the Transformational Challenge Reactor, or TCR. But this one will be quite a departure from the reactors that have come before. It’s going to be 3D printed. TCR aims to revolutionize how a nuclear reactor is built – a process that hasn’t really changed much in the past 50 years. In this episode, you'll hear from some of the lab's nuclear and materials experts, an industry partner using technology coming out of TCR, as well as Rita Baranwal, the assistant secretary for the Office of Nuclear Energy in the U.S. Department of Energy.




DEHOFF: When I first heard we were 3D-printing a nuclear reactor, I was scared to death.

BARANWAL: It is exciting. One thing that needs to change in this industry is to move with a sense of urgency.

ICENHOUR: We're changing the way that you approach building nuclear reactors and that’s pretty cool.



JENNY: Hello everyone and welcome to “The Sound of Science.”

MORGAN: The podcast highlighting the voices behind the breakthroughs at Oak Ridge National Laboratory.

JENNY: We’re your hosts, Jenny Woodbery

MORGAN: And Morgan McCorkle.




JENNY: It’s 1943. The world is at war and the United States has launched a top-secret mission in hopes of ending the conflict.

MORGAN: The Manhattan Project has established sites around the country to support the research and development of the world’s first operational nuclear weapons.

JENNY: In February in a rural area in East Tennessee, ground is breaking on the X-10 Graphite Reactor.

MORGAN: The reactor is modeled after Enrico Fermi’s design of the Chicago Pile, which reached criticality just a few months prior. Its mission is to demonstrate that plutonium could be produced from uranium in a nuclear reactor.

JENNY: Fast forward to Nov. 4, just nine months after construction began. The reactor achieves criticality at 5 a.m., making it the world’s first continuously operated nuclear reactor.

MORGAN: The quick success of the Graphite Reactor established ORNL’s expertise in the nuclear arena.

JENNY: From 1950 to 1965, ORNL built an additional 12 reactors featuring different designs for research in power production, health physics and radioisotopes. Among those was the High Flux Isotope Reactor, which still plays a critical role in scientific discovery and isotope production.

MORGAN: Now – in 2020 – ORNL is looking to build its 14th nuclear reactor. But this one will be quite a departure from the reactors that have come before.

JENNY: It’s going to be 3D printed. That’s right, 3D printed.

MORGAN: The Transformational Challenge Reactor, or TCR, aims to revolutionize how a nuclear reactor is built – a process that hasn’t really changed much in the past 50 years.

KURT TERRANI: TCR, in a nutshell, tries to leverage all the advances in various fields of science and technology, specifically, manufacturing sciences, material sciences and computational sciences, to deliver a nuclear system that’s better than what we could do before.

JENNY: That’s Kurt Terrani. He is the director of the Transformational Challenge Reactor Demonstration Program.

MORGAN: Nuclear energy provides nearly 20 percent of America’s electricity supply. The majority of these reactors were built in the ’60s and ’70s. It’s estimated that by 2055, all current reactors based on light water technology will be ready for retirement due to expiring licenses. 

JENNY: So, the need for advanced reactor systems, like TCR, has never been greater.

KURT TERRANI: Nuclear is the one industry that magically got everything right in the ’50s and ’60s, so everybody else has to continuously improve, but not us. We're just this chosen community and field of technology that's completely peaked and there's no room for improvement. Obviously, I'm being nefarious characterizing it that way; clearly, there's room for improvement.  And so, we want to bring in technologies that are available to us, advanced manufacturing, artificial intelligence, computational sciences, major advances in material sciences. All these things allow us to realize a better system.  




MORGAN: 3D-printing, known more commonly as additive manufacturing in the scientific realm, is the process of making a part by adding layer upon layer of material.

JENNY: This can be done with a range of materials – wood, bamboo, plastic, metal and even ceramics.

MORGAN: As additive manufacturing has become increasingly popular over the past few years, the lab has emerged as a leader in the field.

JENNY: Despite having printed houses, cars and boats, the prospect of printing a nuclear reactor was a little shocking, even to a materials science expert.

RYAN DEHOFF: When I first heard we were printing a nuclear reactor, I was scared to death. I know additive manufacturing quite well. I was extremely skeptical that we were going to be able to take this and put it into a nuclear reactor.

MORGAN: That’s Ryan Dehoff. He’s the thrust lead for manufacturing for the TCR program.

DEHOFF: And after interaction with the nuclear guys, they came back to me and they explained what it was and what we were doing. And it's, oh, I'm just building the big heat exchanger. And they're like, yeah, basically, it's just a big heat exchanger. Oh, well, we can print heat exchangers, that's something additive is really, really good for . So, it kind of helped put things in context about what we were trying to do. It wasn't trying to tackle the world. It was, you know, how can we use this where it makes sense to make a really, really big impact in the nuclear space.

JENNY: Ryan and his colleagues are in charge of manufacturing components for the reactor’s core – which are printed out of stainless steel and silicon carbide.

MORGAN: They’re using two 3D-printing techniques at the Manufacturing Demonstration Facility to accomplish the complex designs within the core. One is called laser powder bed fusion. In this process, you start with a fine metal powder. A laser is used to melt an individual layer of the powder. Those layers add up to form a three-dimensional structure. This technique is being used for a lot of the stainless steel components within the core assembly.

JENNY: The other technique is called binder jet additive manufacturing, which also starts with a fine powder. But instead of using a laser to melt it into a three-dimensional shape, a binding agent is used to essentially glue those powder particles together in a complex geometry.

DEHOFF: The really unique aspect about this process is we're actually able to do this with silicon carbide, which is a really unique material for nuclear. It gives a lot of very interesting properties that the nuclear engineers like. But we actually have figured out a way to process this material at scale that will go into the core of the reactor, and so that's a really exciting development that's come out of TCR.
MORGAN: One of the advantages to additive manufacturing in any industry is how it dramatically reduces the time it takes to produce a part.

JENNY: In the nuclear space, Kurt says this is allowing engineers to design reactor core components and print them in a matter of days and weeks.

TERRANI: Instead of doing six months, one year, two years of design, and then hoping everything's going to be everything's going to work out, how other nuclear projects are being done today, we have these iterations where we go ahead and in a matter of not months and years, but in a matter of days and weeks, we produce a design. We build it, we test it, we learn from it, we measure its properties, we feed it back into our design cycle. And that's how we continuously improve.

MORGAN: Additive manufacturing not only speeds up the design and build process, it also can also offer cost savings – something that’s greatly needed in the nuclear industry.

JENNY: We talked to Rita Baranwal, the assistant secretary for the Office of Nuclear Energy in the U.S. Department of Energy, about the value of additive manufacturing in nuclear.

BARANWAL: I do want to add that it's not just about cost. The beauty of some of these advanced manufacturing techniques is that it allows you to make very complex parts, very unique shapes and geometries that just would not even be possible with our current traditional manufacturing techniques. And there's such a value that needs to be recognized for the ability to make this type of complex component. The value that's seen there may not manifest itself in a lower cost per se, but it creates a more valuable part in the end. And so, we talked a lot about lowering cost, but I think also we should talk more about adding value as well. And advanced manufacturing techniques certainly do that.




MORGAN: You may be wondering, what exactly does a 3D-printed reactor look like?

TERRANI: I can give you dimensions in inches, feet or meters. My favorite size is that it's somewhere between a keg of beer and a cask of wine.

JENNY: TCR is designed to be a microreactor. So, while it’s not that big, it will be very powerful.

MORGAN: To put Kurt’s comparison in perspective, that amount of energy could power about 1,000 homes in the U.S.

JENNY: Inside the reactor, the core’s complex geometries look something like a honeycomb. This intricate design is something that could only be achieved with additive manufacturing.

BARANWAL: I think one of the key attributes of TCR is the use of advanced manufacturing techniques. And what this does when you start to look at those techniques is open up a whole new world of opportunities that we did not necessarily have using standard manufacturing techniques. I remember several years ago leading a team and we were looking at different fuel concepts and we started to get confined to what our manufacturers could fabricate in their shops. And I said, “Let's clean sheet the whole design and forget for a moment what our constraints are. What would you design the fuel to do? What geometry would it look like? And that's what a technology class like additive manufacturing allows for.




MORGAN: The TCR program is more than just producing a single reactor – it aims to provide innovative techniques that can move the nuclear industry forward.

TERRANI: One of the most important things to notice is that we are not building a reactor and saying, “Hey, here's a commercially available-now power unit that a power customer can come and purchase.” No, we are showing how these advanced technologies can be used to rapidly build a safe and reliable and advanced system. These tools in the toolbox can be used by a number of reactor designers.

JENNY: Industry partners are already taking advantage of the advances coming out of the program.

TERRANI: One of our partners is for instance, Kairos Power, they're building a very different type of reactor, they're building a salt-cooled reactor, whereas TCR is a gas-cooled reactor. They fundamentally different reactor types, but the tools are the same – how do you use advanced manufacturing? How do you use artificial intelligence? How do you use things like that to build a system like this?

ED BLANDFORD: My name is Edward Blandford. I'm a co-founder and chief technology officer here at Kairos Power. The Transformational Challenge Reactor program has created an opportunity for Kairos to leverage some of the additive manufacturing capabilities that Oak Ridge is trying to bring into advanced reactor development. And there's actually a lot of overlap between what the TCR program is trying to do and what Kairos is trying to do with our technology in terms of rapid development.

MORGAN: The California-based company has partnered with ORNL to produce a specific part for its own reactor prototype.

JENNY: The part is a closed pump impeller, part of the heat exchanger loop designed to move molten salt through a heat source. The part has to be precisely manufactured to withstand extreme temperatures and fit in seamlessly with the rest of the prototype.

MORGAN: While you could achieve this with traditional manufacturing, the process would be very slow and expensive.

JENNY: The company recognized that this method didn’t work with their timeline or budget.

MORGAN: So, Kairos Power worked with Kurt and his team to additively manufacture the part.

BLANDFORD: What TCR and a lot of the more modern advanced manufacturing capabilities have done, have really brought in this real-time material characterization, and it allows us to boost confidence in the final product’s ability to meet these requirements from the moment a single part is created. Unlike a conventional postmortem style iterative testing to develop a casting process for a new geometry. So, it's really a combination of these benefits and immediate ability to apply these more modern technologies early on the case of additive technology. It's a huge asset to Kairos.




JENNY: One of the unique aspects of the TCR program is that it combines expertise in nuclear, additive manufacturing, materials sciences and computational sciences.

MORGAN: Leaders like Rita Baranwal hope this multidisciplinary approach to building an advanced reactor brings in a new wave of talent to the nuclear industry.

BARANWAL: I think when we look at wanting to bring in a pool of talent that is going to contribute to our industry, we need to make sure that the things that we're working on are attractive to that incoming talent pool. And I think the topics that TCR is addressing are very enticing. They're very exciting. They're very interesting. There are now college undergraduate majors in additive manufacturing. And so that really speaks to the expertise that is being dedicated to these areas and that we could, for example, hire somebody with degrees in this very specific type of manufacturing tells me that we're on the certainly on the right track with TCR.

JENNY: Alan Icenhour, who is the associate lab director for the Nuclear Science and Engineering Directorate at ORNL, sees this as a moment for the next generation to make a lasting impact on the field much like the nuclear pioneers of the lab’s past.

ICENHOUR: I always say when I look around this laboratory, it's easy to point to the foundation that was laid for us. We're still using that High Flux Isotope Reactor, which was conceived in the early 1960s and went critical in 1965. That's an elegant machine that does so much important science and isotope production, as well as helping us advance the materials. Having the foresight to put those capabilities in place are one of the most important things we can do. And having in place projects like a TCR is something that's tremendously exciting to people because they see the opportunity to make an impact today, but I would say it's an impact that’s going to be lasting. We're changing the way that you approach building nuclear reactors. And that's pretty cool. And it's those kinds of things, having projects like that, that I think, are an attractor, to people want to do their work in this area. And so, it's important that we continue to really get these compelling projects, you know, that t can bring in the next generation of scientists and engineers.




MORGAN: We talked a little about the Graphite Reactor at the beginning of the episode. Even at 77 years old, this historic landmark continues to inspire and spur innovation at the lab.

ICENHOUR: I always say, the Graphite Reactor is a reminder to all of us, of what we are actually capable of. What an ambitious undertaking. What a challenge. The foundation of that reactor was to demonstrate you can make gram quantities of plutonium. The only problem was nobody ever built a reactor before. Nobody really knew what it looked like. And so, it's astounding. But it's the kind of approach we still take today. A multidisciplinary team was formed with a really compelling challenge to deliver. That's really a motivator for why we're doing TCR.

ICENHOUR: It is Transformational Challenge Reactor, and each of those words has really substantial meaning to us, from standpoint of we're trying to do something that's transformational, you know, changing the way of working in this area, it's a huge challenge. Okay. And then obviously it's a reactor. So maybe that's goes without saying but those kinds of things are what national laboratory should be doing

JENNY: While it will take longer than nine months to get TCR up and running – due to much more rigorous safety standards that are in place today – the team is looking to complete the demonstration in 2023.

MORGAN: It’s an aggressive timeline, but Rita Baranwal sees tight schedules like TCR’s as key to DOE’s vision for advanced reactor deployment in the U.S.

BARANWAL: The reason for that relatively tight timeline is to maintain our technology leadership around the globe. Our competitors are very, very quickly scaling up and deploying advanced reactor technologies around the world. And we certainly do need to keep pace and so hence the word folks are calling a pretty aggressive timeline of five to seven years. And so to continue to compete, we certainly need to change some of the things in the way that we do some things and certainly the computational science and the advanced manufacturing techniques that are being developed and demonstrated in the TCR project represent and embody what we need to be doing differently.



JENNY: Thank you for listening to this episode of “The Sound of Science.”
MORGAN: Interested in getting updates on the TCR program? Visit

JENNY: If you enjoyed this episode, be sure to leave us a review wherever you get your podcasts.

MORGAN: Until next time!