A Nuclear Career Spanning from Egypt to North Carolina (0:48)
0:48-11:11 (Mohamed Bourham’s path to a career in nuclear from Egypt to Europe to North Carolina State University)
Q: When did you first arrive at NC State?
A: Mohamed Bourham first arrived at NC State in Raleigh, North Caroline in 1987. He was born in Egypt, growing up there and starting his career there. Mohamed also spent a lot of time in Europe before coming to the U.S. He received his B.S. in from Alexandria University in Egypt, where all of Egypt’s nuclear professionals get their degree. He then got his Master’s degree from Cairo University and his PhD from Ain Shams University. In June 1965, Mohamed graduated with his B.S. and, by July, was in the Nuclear Research Center of Egypt, a part of the Atomic Energy Authority established in the 1950’s. In October, he was officially appointed as a research engineer in the Department of Plasma Science and Ion Sources. At that time, there was a 2 MW Russian-type research reactor in the Nuclear Research Center. Mohamed was involved in future fusion energy research. A couple years later, the Nuclear Power Plant Authority was created to look into the future production of electricity from nuclear power plants. A site was set aside for the reactor, but the plan was never implemented. The Nuclear Research Center updated their nuclear facilities to a 22 MW research reactor, built under Argentina, and is also used for isotope production for medical uses.
In Europe, Mohamed did plasma and diffusion research in England, Germany, and other countries. When Mohamed came to NC State, they were heavily involved in developing all the techniques needed to support the future of fusion energy. The international system started to show up under ITER and Mohamed became involved with the Department of Energy (DOE). In this program, Mohamed’s students studied problems such as the effect of very high heat flux on components and materials. They became involved with electrothermal plasma sources, which was started with the Department of Defense. This concept allows for propulsion systems and was considered as a pre-injector for rail-guns. He became highly involved in research for the concept and materials needed to survive in this environment, working alongside the Ballistic Missile Defense Organization, Strategic Defense Command, Army Research Laboratory, and the Office of Naval Research.
Mohamed’s Research at NC State (11:11)
11:11-25:21 (Mohamed reviews his many areas of research, including electrothermal propulsion, radiation, waste, and material science)
Q: What is the research, exactly? Are you trying to understand how materials behave or the behavior of the plasma itself?
A: Mohamed and his team understood the impact of the sources and its performance on the integrity of the materials, since it is subject to very high heat, pressure, and exit velocities, up to 7 km/s. This research was taken into the fusion arena because, it they could achieve very high propulsion, it could be used as a fueling mechanism for fusion reactors by accelerating a frozen deuterium to 2-3 km/s so the fuel can get to the core of the fusion reactor before it evaporates. NC State has developed a lot of codes for this, doing all sorts of experimentation and computation. One of Mohamed’s PhD students shuttled between NC State and Oak Ridge National Laboratory, which has an operational electrothermal gun. This student also went to San Diego to go to General Atomics to run experiments on their Tokamak reactor. He was eventually chosen to be a postdoctoral student at ITER, the single individual chosen from the U.S.
Mohamed also took another branch into radiation and waste. NC State got into this research by providing techniques like various codings that provide various barriers and different forms of concrete. Mohamed and his students now have plasma, shielding, and coating as different areas of research. A new contract with the Department of Energy (DOE) looks at non-intrusive sensors that can be used in a nuclear environment, including reactors. The sensors are not inside the reactor, but are outside the reactor and the piezo crystal launches a surface wave which propagates to another exterior detector. Through this pass of the surface wave, measurements of phase change and signatures are detected which are a function of the interior temperature and pressure. The internal conditions being measured are temperature, flow and level of the coolant, and pressure. This project is under a DOE program called NAUP, Nuclear Engineering University Programs. The university can also submit a grant application for equipment, which they have done in the past for a dual ion beam irradiation system and an autoclave stress corrosion.
NC State is also doing a lot of research in materials science. Additional materials, such as lead, could be added to concrete. This has the potential to achieve the same attenuation with a smaller thickness, leading to a reduction in the mass and the cost. Radiation protection is a matter of the specific density of the material. Linear attenuation coefficient is a material-related characteristic, highly dependent on the material. This is transferred into the mass attenuation coefficient, which incorporates the specific density. Mohamed has recently seen a lot of research going on into adding glass components to concrete because of the element of composition. The coefficients are functions of how interactions with the materials take place.
Dry Cask Storage for Nuclear Waste (25:23)
25:23-37:52 (How dry cask storage for spent fuel has performed so far and why there are different ideas about nuclear waste storage)
Q: How do we think about this attenuation coefficient? Is it just a function of the density of the element?
A: The relationship between the coefficients are part of an exponential relationship. The coefficients are functions of how interactions with the materials take place. Most of the focus for waste storage is focusing on the gamma instead of the neutrons. Gamma also produces heat. In the dry cask, there is the spent fuel with an air gap between the fuel and the concrete. The dose rate outside can be calculated to make sure it is within acceptable units. This topic can go very political. Yucca Mountain is a beautiful site as a repository, with a vertical shaft entrance and tunnels with vaults. Most of the spent fuel remains in a large vault on the nuclear power plant site as it cools down before being transported into the casks. The casks are kept within the premises of the nuclear power plant. The repository provides more safety. Most dry casks are performing very well and are a good technique good for 300, 400, or 500 years. Mohamed Bourham does a lot of modeling for dry casks. In collaboration with some colleagues, one of the dry casks was opened after so many years to check for corrosion. Usually, it will not be opened and once it is sealed, it is sealed. During this one inspection, they found that everything looked good and the dry casks performed very well. Other techniques looked at including different concrete or liners to be heat absorbers inside the dry casks.
There is a mix between science, technology, and politics. As researchers, Mohamed and his team look into best thermal barriers, best concrete compositions, and other endless forms of research. NC State talks with Savannah River, Los Alamos, and others like Hanford to provide solutions. It is time now that the world gives a good focus to nuclear waste. It has not been given this much interest in some time. Over the past three years, Mohamed Bourham spent two years working heavily on electrothermal plasmas. One year Mohamed was heavily involved with corrosion studies and different materials used in canisters. He currently has four students studying topics like concrete and concrete forms, coated materials, electrothermal plasmas, and non-intrusive embedded sensors.
Materials and Magnets in Fusion Reactors (37:52)
37:52-47:26 (Mohamed explains how fusion is controlled with magnetic fields and the impact it has on materials in the fusion reactors)
Q: Let’s talk about fusion and materials. Is the Sun a perfect sphere?
A: The Sun’s shape is almost very close to a perfect sphere because it is a gaseous form of hydrogen and has a huge mass, giving it a huge gravitational force. In fusion research, fusion is controlled by a magnetic field instead of gravity. The magnetic field provides a form of a pressure and squeezes the plasma. It also provides a form of confinement and forces the ionized pieces to rotate around the field so they can’t escape. As the magnetic field is applied, the radius gets smaller and smaller and the particles can be controlled. If there was a sudden failure in the magnetic field, called a disruption, all of the particles will find their way inside and through the walls. Mohamed Bourham studies the impact with the materials and the response of the materials to the high heat flux. There are actually three magnetic fields in the Tokamak reactors and there are some features with which one can suppress the disruption so it is not at a high frequency. These magnets are huge and it is an amazing engineering achievement to create these types of magnets. The materials in the Tokamak are important, from the first wall inside to the bottom where the divertor extracts energy and removes ash.
The JET, Joint European Torus, in England is all beryllium inside because it is a very low z material in the beginning of the table and is light. Beryllium’s vapor is very toxic. The test facility built at MIT had tungsten and the one operated by General Atomics has graphite. The study of materials for fusion reactors spread over decades. The interaction from the heat flux point of view and also the impact of the charged particles factor in to the materials. If the reactor is operating using deuterium/tritium mixture, there will be a production of heavy alpha particles and neutrons produced. It is the irradiation that causes material hardening, cracking, and sweating. This is expected to happen in future fusion reactors because there are neutrons. Most of the material research is conducted under the Department of Energy. General Atomics is one of the companies doing a lot of research related to fusion materials and operates their own Tokamak, called the National Fusion Facility. In ten years, the world will start to see the first test reactor that proves the feasibility is there and it can be run and controlled. It can then move into commercialization in the next ten to fifteen years.