Appointment with... Prof. Christian Reiter

Prof. Christian Reiter is a physicist and has been closely involved with nuclear research at TUM for many years. After his diploma and doctorate at Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II), he deepened his expertise in design and simulations for reactor operation as head of the Reactor Physics department. His transdisciplinary and international focus led him, among other things, to take up a position as an adjunct professor at McMaster University in Hamilton, Ontario/Canada. On 15 October 2025, he was appointed Professor of Applied Nuclear Technologies at the TUM School of Engineering and Design (TUM ED). In the interview, he talks about sustaining expertise in nuclear technology, reactor designs, nuclear medicine, and tritium production for the fusion energy of the future. 

ED: How did you become who you are today?

Prof. Christian Reiter: I have been fascinated by mathematics and physics from an early age. My father is an astrophysicist, so studying the natural sciences seemed like the obvious choice. Mathematics was too abstract for me, so I chose physics. However, by the time I got my diploma, I wasn’t quite sure which research area I would end up pursuing.

Through the Reactor Physics lecture, I joined the fuel group at the FRM II research reactor, which was working on retrofitting the reactor. That was my introduction to nuclear engineering. My diploma thesis on fuel development was experimentally oriented, but for my dissertation, I wanted to explore the other side: simulations of reactors, failure scenarios, and transients, i.e., time-dependent scenarios. This is particularly interesting for research reactors like the FRM II. That’s when I became a “nuclear nerd,” if not before. I’m fascinated by the broad spectrum of scientific questions that can be investigated using research reactors: from simulations and regulatory issues to applied work at the reactor that directly addresses the challenges facing our society. 

How did you reorient after Germany's exit from nuclear energy?

To start with, I’d like to say that I consider basic research in nuclear technology to be immensely important, as it spans the entire spectrum of advanced technologies relevant to the challenges our world faces. I was personally affected by the phase-out of nuclear energy. In my lectures, however, I set that aside and aim to teach students the fundamentals of this technology. It’s perfectly fine to still reject nuclear energy after the lecture. However, you should then have a solid understanding of its potential and limitations in order to make informed decisions about its use, such as for power generation.

The phase-out of nuclear energy has massive consequences for research that we must adapt to: topic-specific third-party funding pools are shrinking, and the range of topics is becoming more limited. Nevertheless, we at TUM continue to train the experts who will drive and further develop research in the future. Another consequence of the exit from nuclear energy is that we must focus more strongly on the international market and join forces with partner organizations and universities in order to succeed as a larger unit. This will allow us to become more versatile in teaching and research.

Throughout your many years at TUM, you have been actively involved in a wide range of research topics in nuclear technology. Which research projects are you currently leading?  

First of all: TUM is the university in Germany with the greatest potential for nuclear research. Nuclear technology goes way beyond just power generation. A large power plant simply wastes 60 percent of its heat – that’s hardly sustainable. At the same time, nuclear fission produces free neutrons that can be used in a wide variety of ways, from archaeology to biology and geosciences all the way to medicine. A key project is the retrofitting of the FRM II to use low-enriched uranium. This is a challenging task, as our team is essentially developing a new reactor within an existing facility. This project is also a unique training program: Our students and doctoral candidates take on tasks that were previously handled by Siemens KWU. They learn everything—from the fundamentals of nuclear fission to the preparation of documents eligible for approval by regulatory authorities. This unique offering is only available at TUM.

Additionally, we are working intensively on medical radioisotopes, such as lutetium-177 for cancer treatment. These radioactive atoms bind to a bioactive molecule. The therapeutic substance travels through the bloodstream directly to the tumor tissue, where it delivers targeted radiation to the malignant cells. Together with TUM Klinikum Rechts der Isar and the company ITM Isotope Technologies Munich SE, we are investigating why therapies work better in some people than in others. To do this, we calculate dose distributions within the tumor and analyze the biological efficiency. Why does this treatment work well for one patient but not for another? When is transport to a tumor more or less effective? It is an extremely interdisciplinary, exciting field that researchers in reactor physics and nuclear engineering can pursue, and it is currently growing exponentially in the market.

Another area of focus for the future is tritium production for fusion research. Future fusion power plants will require enormous amounts of tritium—far more than is currently available worldwide. We are working together with the Karlsruhe Institute of Technology (KIT) on concepts for efficiently generating tritium in fission reactors and establishing a Germany-based supply chain. To put this into perspective: The Karlsruhe Tritium Laboratory (TLK) at KIT currently holds a handling permit for 40 grams of tritium. For a future fusion power plant, we need 100 kilograms. To achieve this scale, we submitted a joint proposal for this major project at the beginning of the year. In the long term, TUM aims to develop tritium expertise that complements the TLK, including its own infrastructure.

What changes are you hoping for in the Future?

For TUM, I wish that interdisciplinary collaboration continues to grow. My appointment to the TUM School of Engineering and Design was an eye-opener — suddenly, many things became pragmatically and easily possible. This “can-do attitude” is incredibly beneficial for core technology. I also hope for less bureaucracy in our society. A lot of energy is wasted when you have to print out digital forms and then scan them back in. More efficient processes and additional administrative staff would be very helpful.

From a societal perspective, I would like to see a genuine, technology-open discussion. In Germany, new technologies are often reflexively met with skepticism. When it comes to fusion, the first thing people talk about is regulation, long before a single plant has even been built. What we need instead is greater pragmatism and a willingness to understand technologies before judging them. In the field of nuclear technology in particular, I often find that communication lacks a solid foundation. After the Chernobyl nuclear disaster, the public was given little explanation of the causes and underlying factors, which eroded trust. If people are engaged at all levels—from casual discussion to expert debate—it becomes possible to talk objectively about opportunities and risks. Only in this way can genuine acceptance emerge.