Reddit Engineering “Ask Me Anything” Event Recap

Earlier this week, Phoenix held its second-ever AMA (“Ask Me Anything”) session on Reddit! Read a recap of how it went.


Earlier this week, Phoenix held its second-ever AMA (“Ask Me Anything”) session on Reddit! CEO Ross Radel and President Evan Sengbusch joined engineering manager Chris Leyen, nuclear engineering manager Eli Moll, research engineer Brandon Jackson, and R&D test engineer Ben Johnson to field questions from Reddit’s engineering, fusion, and nuclear communities live during a two-hour block on Tuesday, September 15. Questions ran the gamut from the practical to the theoretical, from the general to the nitty-gritty. We answered Reddit users’ questions about the current and future role of nuclear technology, the steps we’re taking toward fusion energy, career paths in the nuclear industry, and what it’s like to work at Phoenix.

Here are a handful of the interesting questions and answers from the AMA:

I’m not a nuclear engineer, so maybe this is a silly question, but one thing that’s always baffled me about the concept of nuclear fusion as a feasible energy source is the high temperatures required for the atomic reactions to occur. Is it even possible to create a structure that can contain such high levels of heat? It's my understanding that very large atomic bombs (such as Царь-бо́мба) require the use of a nuclear fission reaction to produce enough heat to cause the next set of fusion reactions to occur. Given the absolute destructive power of that level of energy, how is it proposed to be harnessed in a productive way?

Ross: This is a great question, and the destructive aspect is a matter of energy density. Any fusion energy production system will have energy densities many orders of magnitude below that of a weapon, so there won’t be the concern about the destructive nature.

To the first part of the question, the keys to fusion energy is finding a way to simultaneously maintain sufficient temperature, density, and confinement time. There are many approaches to achieving these three elements, but the most common involve the use of RF or electrostatic methods to heat a plasma, magnets to confine those charged particles away from any physical wall, and good design (stability) to keep that system in equilibrium as long as possible. One of the key enabling technologies for practical fusion systems is stronger magnetic fields, and recent advancements in superconducting magnets is getting the world closer to making fusion a reality.

Once heat is released (in the form of energetic ions and neutrons mostly), there is a heat flux hitting the walls that the materials need to withstand. That’s not a fundamental challenge from a heat flux perspective, but the neutrons make it really tricky since they will change the material properties of the wall over time. That material science research is an area where Phoenix is contributing by developing a “test stand” with intense neutrons to evaluate potential materials.

What is the biggest use for nuclear technology globally? Is the power industry still larger than medical (or other industries)?

Evan: Energy production is still by far the largest use of nuclear technology, both in terms of dollars and in terms of people that work in the nuclear field. That is likely to remain true for the foreseeable future. Even if fission-based nuclear energy production stagnates or decreases, it will be supplemented by fusion-based energy production efforts, all of which are currently still in a development phase.

Other major uses of nuclear technology include healthcare (diagnostic imaging, radioisotope therapy, etc.) and industrial inspection, among others.

I was wondering if you guys had any recommendations or advice for a recently graduated mechanical engineer trying to break into the nuclear field? What sort of qualities do you usually look for in your engineers? Also, you mentioned using fusion technology primarily for medical and testing applications, but is Phoenix also looking at the application of fusion towards energy?

Chris: Thanks for your interest! I, too, am a BSME, but I did not enter this industry until several years ago. Aside from targeting a graduate degree in Nuclear Engineering or Physics, you could establish expertise in one of the ME-based contributing technologies such as heat transfer, vacuum technologies, or structural modeling and analysis. Another angle is to look for a position as a manufacturing engineer with Phoenix. My route happened through software development balanced with project management. If you are driven, curious, and have an appetite for learning, I would recommend you apply to one of our open positions.

Eli: I’ll piggyback on Chris’ answer here a bit. Nuclear engineers (and plasma physicists) are far fewer than mechanical, electrical, software, and production engineers here at Phoenix. Our company couldn’t survive without balancing all of our engineering needs and disciplines! The best advice I could give you is to learn about what interests you (and also learning a bit of coding never hurts).

What’s the future look like for the industry in the next five years? 10? 50? I want to believe that people are becoming more open to the technology as a resource for power generation, but unsure. What are major technical limitations right now that people are trying to solve?

Eli: Great question. The application of fusion technology is rather wide, so I’ll attempt to address the question in a couple of ways. For the long term there are still several difficult hurdles to pass prior to utilizing fusion reactions as a primary power source (magnet design, first wall design, etc.). As Ross mentioned, material degradation via radiation damage is just one of the key problems that must be solved, but this requires testing environments in which such damage may be observed in the presence of high energy neutrons. IFMIF (International Fusion Materials Irradiation Facility) is an example of a high energy material testing site utilizing D-Li reaction that could potentially be online by 2030, but this facility would be required for material testing and design prior to the successful design and operation of a fusion power facility assuming all other scientific hurdles were crossed by that point. However, in the shorter term there is certainly a balance of attempting to deploy lower intensity testing facilities in shorter time frames and at lower cost. All of this is part of an iterative approach to design which will be required to move the supporting technologies for nuclear fusion forward.

Taking a step away from nuclear fusion as power, the future of nuclear fusion as a source of neutrons for the aerospace, medical, fission power, and defense fields is incredibly bright in both the near and far term. The ability to generate high intensity and high energy neutron fields is incredibly important for neutron imaging, non-destructive testing, medical isotope production, nuclear fuel testing, etc. Many previously existing systems which utilized radioactive sources or nuclear reactors may be replaced with accelerated driven nuclear fusion systems which are inherently safer and can be tailored to the desired performance. This is the trade space in which Phoenix operates and excels. If you have more specific questions please don’t hesitate to ask!

What does the typical day look like for you all? Especially in the physics/mechanical realms.I'd like to get into R&D eventually—what do you look for in candidates for R&D positions Experience? Skills? I feel like a significant majority of these sorts of positions are reserved for those with either higher level education or X years of experience…

Ross: There is a wide “gray area” at Phoenix between R&D and engineering, given the nature of our products. I think that provides more avenues for our engineers to migrate into the R&D realm.

For those looking to get into R&D directly here, we certainly look into the candidate’s experience working on complex projects. We don’t have any hard and fast rules about education or years of experience, but we do look for relevant experience at past companies, graduate or undergraduate research projects, or even outside of work.

What experience is needed for an electrical engineer 2 or 3 position?Would you rather take an engineer with three years’ experience in many different areas of expertise and a fast learner, but none related to the field you are in, or someone with the same three years experience, but in one field, and already stuck in their ways?Does being an MSOE alumni mean anything for you?What are your thoughts on engineers who enjoy volunteering at maker faires to hopefully help bolster a love for STEM at all ages?

Chris: At Phoenix, we are interested in all candidates that have an interest in Electrical Engineering and nuclear technology for our open positions. There are benefits to both of the scenarios you presented. It is worth mentioning since Phoenix is such a unique knowledge space, being a curious and capable learner helps a lot. MSOE is a great school here in Wisconsin! While the balance of our team members are from the University of Wisconsin, Brandon Jackson is an MSOE grad!

Brandon: I received my undergrad degree from MSOE in Mechanical Engineering in 2012. There are at least three MSOE alumni working here.

We are always open to individuals with diverse backgrounds. It brings in new trains of thought. Prior to working at Phoenix my background was in electric spacecraft propulsion.

Jake: Like Brandon mentioned, we have a few MSOE alumnus and we are always happy to bring more onto the team. And we are huge proponents of STEM outreach! We actually have a team directly focused on STEM outreach and education in the community (schools, local organizations/non-profits, etc…). Not to toot our own horn here (but also to toot our own horn), we think we do some pretty cool stuff at Phoenix, so we want to share that and get people interested early. We actually started a partnership with a local non-profit this year called Madym which focuses on providing girls and youth of color in grades 6-12 with skill-based training for the technology sector.

What types of technology is Phoenix investing in to develop viable fusion energy? I know there are some big technological hurdles to overcome before we get there, so I'm curious as to how Phoenix's work is contributing.

Evan: One of the key engineering challenges in making fusion energy practical is developing and testing reactor materials that can reliably withstand the intense radiation environments near the core of a fusion reactor. Specifically, components in that region will be subject to incredibly intense neutron fluxes, beyond anything mankind has ever been able to simulate or test. Phoenix is currently being funded through multiple different sources within the US Department of Energy to further increase the yield of our intense beam-target fusion neutron sources to serve as the technology foundation for a “Fusion Prototypic Neutron Source” which will be used to simulate the neutron radiation environment in fusion reactors. We are hoping to be a key contributor to a $100M+ test facility that will serve the global fusion energy development community in the coming decade.

Another area we are indirectly contributing is in the development, testing, and licensing of tritium handling technologies. Many fusion reactor concepts rely upon the DT fusion reaction, meaning they must be able to safely and effectively manage tritium gas, which is radioactive. Our systems also use reasonably large quantities of tritium gas and are in operation today. The experience gained in safely and effectively using tritium in fusion systems, even for non-energy applications like medical isotope production, will greatly accelerate the pathway to commercial fusion energy.

I’m a mechanical engineer just about to move to the medical isotope field. How do you see that industry developing in the near term (especially for domestic supply) and do you hope that that will be the core part of your business?

Evan: You’ve picked a good field, as it will certainly be growing!

The biggest global market trend we foresee is increased use of radioisotopes for therapeutic purposes, specifically cancer treatment. Radioisotopes are already widely used in diagnostic imaging in procedures like Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET). However, the use of radioisotopes for the treatment of disease is still limited to just a few indications like Iodine-131 to treat thyroid cancer.

Just in the last few years, there has been some really promising clinical trial results from radioisotope therapy for very widespread diseases like prostate cancer. Isotopes being evaluated include Lutetium-177 and Actinium-225, beta and alpha emitters, respectively. We predicted that in 5 years from now, these isotopes will be used widely in clinical practice.

In terms of Phoenix’s direct contribution, we are building the fusion neutron sources that will power a US-based medical isotope production facility currently under construction by our sister company, SHINE Medical Technologies. That facility will utilize a subcritical fission-fusion hybrid approach to create diagnostic and therapeutic isotopes that historically had been produced at nuclear reactors.

I’m currently a high schooler with a very loose understanding of nuclear physics, but i am interested in learning more. I can take physics next year but the class doesn’t cover nuclear physics. What are some good resources for me to learn more about this?

Brandon: Check out the following:

  • MIT Open Courseware is great—lots of Youtube lectures
  • So is EdX—Great lectures, you can probably skip over the coursework if its at too high of a level
  • The Great Courses Plus has an excellent series on nuclear physics called “Nuclear Physics Explained”

I actually took advantage of a Great Courses sale just to see that last course, but I bet you can get it through your library.

I’m interested in a job at Phoenix, LLC. I am wondering, what are the chances of being subjected to harmful levels of radiation and, subsequently, receiving superpowers?

Eli: Sadly your chances of being subjected to harmful levels of radiation are zero, and even more sadly, we have no documented cases of superpowers on site.

Ross: I’m still holding out hope that the small, unharmful levels of radiation I receive as a radiation worker will result in superpowers. Fingers crossed.

There is a ring-shaped zone inherent in any nuclear blast, wherein all the frozen pizzas in all the store freezers are cooked to perfection. How would I calculate this zone, just in case?

Chris: Due to the error terms in modeling, the balance of simulations recommend that you should not eat frozen pizza.

See the full Ask Me Anything on r/Engineering

See our previous Ask Me Anything on r/AskScience