Eben Mulder

Ep 160: Eben Mulder - Senior Vice-President & Chief Nuclear Officer, X Energy
00:00 / 01:04


Q1 - South Africa’s Atomic Energy Corporation

Bret Kugelmass: What is your personal history and how did you get into nuclear?

Eben Mulder: Eben Mulder is originally from South Africa, where he was proficient and interested in pure mathematics and theoretical physics. After serving his two required years in the nation’s army, Mulder became interested in the mechanics of explosions. Mulder started working at the Council for Scientific and Industrial Research where he transitioned from scientific to industrial work. Part of the Council had spun off to form the Atomic Energy Corporation; the Corporation sponsored Mulder’s education and Mulder started working on the reactor development program. The nuclear proliferation treaty was signed during Mulder’s time at the Corporation, which had previously developed a nuclear weapon. They tried to pursue fuel enrichment through centrifuges, but could not find the right combination of materials. South Africa also attempted laser enrichment. Mulder’s background is physics-based, but his PhD is in nuclear engineering.

Q2 - Challenges of Scaling Nuclear

Bret Kugelmass: When it comes to fluids work, is it easier to scale in size as there are inherently less boundary conditions?

Eben Mulder: All of the phenomena manifested in large fluids system, happen in small systems but may not necessarily be noticed or impactful. South Africa intended to develop a pressurized water reactor. As reactors are scaled down, the system should become simpler and a number of safety systems should be closed down. Nuclear energy works well in a submarine because it is surrounded by a natural heat sink. Eben Mulder doesn’t see economic benefits of smaller reactors, but is excited to see a reactor design that is intrinsically safe, which brings cost benefits. The Atomic Energy Corporation closed down the enrichment facility and many of the engineers went to Eskom, the state-owned utility. The utility, which is run by a majority of coal power, was confronted with looking at future supply side options including nuclear. However, the nation’s two nuclear plants were built 1000 miles apart, requiring massive transmission systems. Sixty-five percent of Africa’s utilities come from South Africa. The gold industry was very energy intensive and funded the start of the utility company, Eskom. The company comprised of three businesses: generation, transmission, and distribution.

Q3 - Mulder’s Introduction to Pebble-bed Reactors

Bret Kugelmass: How has the environment in South Africa changed over the years?

Eben Mulder: South Africa has vast population differences, which was effectively ruled by Europeans for many years due to its strategic location at the Southern tip of the continent. South Africa was vehemently against communism, as Russia was interested in the ocean transportation advantages of the country. Over 60% of all the asphalt roads in Africa are all in South Africa, but within the country, there is a huge contrast between the first world living and the developing side of the population. Usually, first world technology gets developed in first world countries, but Eben Mulder’s dream was to bring nuclear technology to the country. He viewed the only way to get South Africa freed from continually following the trends and bad habits of other African countries was to take nuclear technology in hand. Mulder studied nuclear energy in Germany, whose nuclear experts looked at South Africa’s enrichment processes. Their system had a fixed wall centrifuge which used turbines or compressors to blow hydrogen (carrier gas) into the cascading system to get the same effect as a spinning centrifuge and was able to separate the material. The helium isotopes and the uranium isotopes separated and were funneled upward. Once South Africa signed the nuclear proliferation treaty, the country eliminated all of its weaponry that it had developed. South Africa was not aware of pebble-bed and prismatic graphite-moderated reactors, but Mulder learned about the technology while in Germany.

Q4 - Cooperation Between Germany and South Africa

Bret Kugelmass: What is the TRISO particle?

Eben Mulder: TRISO particles are a type of micro fuel particles. Pebble-bed reactor technology was developed in the U.S. by Farrington Daniels. He suggested that the technology be coupled to a Brighton cycle, one method of converting energy into electricity using helium as an alternative to a steam cycle. South Africa had experience with turbines for the fuel enrichment program and had developed their own compressors. Germany was impressed with the technology, which used helium as a working medium, and suggested coupling a direct cycle to the equipment. Mulder was intrigued with the pebble-bed technology, and realized that the round spent fuel pebbles could be transported in pipes. Mulder worked at the research institute on the AVR reactor on-campus in Munich. The group agreed to allow Mulder to transfer the technology to South Africa. He wanted to understand the physics of the system and Germany sent some financial support to South Africa to get the program going. Mulder met the head of Exelon during a trip to the U.S., who visited South Africa and was intrigued by the technology. Eskom, at the time, was very open-minded about innovation, including installing 1000 kV transmission lines and built the first dry-cooled power station at Matimba. The dry-cooled technology was need due to the arid climate and the plant was built with over 280 fans for a 4,500 MW plant.

Q5 - Mulder’s Impact on Nuclear Education

Bret Kugelmass: What was the duration of the pebble-bed project and what happened?

Eben Mulder: South Africa worked together to design the plant and make the fuel pebbles. When Eben Mulder went to Germany the first time to develop code for safety of light water systems, he went to visit the THTR (thorium high temperature reactor). He was attracted to the technology, went to Eskom with a future supply side option, and returned to Germany where he met the gentleman who led the pebble development program at the research center in Munich. One attractive feature of the technology is that a majority of the components could be manufactured in South Africa and it could be built small enough to be placed near the areas of need. Strategic studies showed the companies being out of energy by 2008. Development was completed and the country put over $1.2 billion dollars into the program, but it became too much of a social program involving untrained individuals from Eskom. In 2006, Mulder left the pebble-bed reactor to look at the succession plan. He started the postgraduate school for nuclear science and engineering at North-West University, the only one of its kind in Africa. Student exchanges took place and the teams built test models in cooperation with the plant for $50,000. The cold critical facility consisted of reflector blocks with pebbles and could predict when the plant would go critical. Contour rods could be modeled with different code. Mulder sees success in new technology development with better people management and resolved issues with obtaining licenses, which complications the relationship with the client.

Q6 - Politics and Pebble-bed Technology

Bret Kugelmass: How did you get involved with X Energy?

Eben Mulder: In 2010, there was a new government transition and the pebble-bed reactor was abandoned to provide funding for the World Cup soccer stadium. Between 2006 and 2012, Mulder’s nuclear program at North-West University produced 150 PhD’s and Master’s degrees. Mulder handed over his code to the university program and assembled a team of experts to work together on a small 30 MW concept pebble-bed reactor. In 2013, the team came to the U.S. to complete a design review. Dr. Kam Ghaffarian, the founder of X Energy, reached out to Eben Mulder and invited him to work in the U.S. on the project. At the time, Mulder was director of a rare earth mine in South Africa that produced thorium as a byproduct of the mining operation. Mulder formed Steenkampskraal Thorium Limited (STL) which got a license to take the thorium that was separated and put it in the mine again to create a bank of thorium. Mulder’s families, along with seven others, moved to the U.S. to pursue the pebble-bed reactor technology.

Q7 - Licensing Challenges of New Nuclear Technology

Bret Kugelmass: What stage of technological development is the pebble-bed reactor at right now?

Eben Mulder: Eben Mulder is familiar with and confident about the capabilities and functionality of pebble-bed technology. Dr. Kam of X Energy pursues projects that make financial sense, looking forward to the impact on climate change the technology can provide. The clientele has been put off by challenges of obtaining a license for this specific technology. However, it is difficult to get traction in the licensing process without having a committed clientele. Mulder aims to demonstrate the capabilities of a full-scale plant in the U.S. first before spreading across the globe. If fuel pebbles are only passed through the system once, there would be a very high power peak and the top and very little utilization. Instead, the reactor is designed as a multipassing system in which the pebbles are passed through multiple times. Fuel can be withdrawn and refilled while the plant is online. The original design was a 30 MW once-through reactor.

Q8 - Evolution of X Energy’s Pebble-bed Reactor

Bret Kugelmass: What changed with the pebble-bed reactor technology?

Eben Mulder: X Energy’s marketing division completed a study of the market focused on which states are pro-nuclear and where replacements would be required. The current design is a 200 MW thermal unit. The designer must show that the materials are not being challenged in the power plant; designers use ASME standards to design within material limits. The plant’s inlet temperature of helium was prescribed at 300 degrees Celsius and outlet temperature at 750 degrees Celsius, still in a steam cycle conversion. A heat exchanger then takes the hot Helium gas and turn it into steam, resulting in a temperature of 550 degrees Celsius, a temperature adequate for processed applications. During construction and initial operation of new technology plants, some design considerations not made in initial stages are discovered and must be addressed. Mulder suggest sticking to the standard supply chain and what is known, instead of experimenting with new components.

Q9 - Value of Nuclear Energy for Future Generations

Bret Kugelmass: Why is nuclear technology important to you?

Eben Mulder: Eben Mulder believes that nuclear technology is a sustainable source of energy. If it can be made available to future generations, they can solve the world’s remaining challenges. Energy they need can be produced without the legacies that the world is generating in today’s energy production.

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