ORNL Research Profile: Leonardi Tjayadi
As a participant in the Nuclear Engineering Science Laboratory Synthesis Program at Oak Ridge National Laboratory, Leonardi Tjayadi performed experiments to investigate different materials for fission and fusion reactors.

Leonardi Tjayadi wants to do his part to ensure the safety and reliability of nuclear energy.

With that goal in mind, the doctoral student from North Carolina State University (NC State) is focusing his research efforts on improving the structural components of nuclear reactors.

To complement his research in nuclear materials at NC State, Tjayadi recently interned at Oak Ridge National Laboratory (ORNL) through the Nuclear Engineering Science Laboratory Synthesis (NESLS) Program. The NESLS program provides nuclear engineering research opportunities for undergraduate and graduate students.

Under the guidance of Xunxiang Hu, Ph.D., a staff scientist/Wigner Fellow in ORNL’s Materials Science and Technology Division, Tjayadi helped investigate the retention of deuterium, an isotope of hydrogen, in the advanced steels of fusion reactors. Fusion happens when two atoms slam together to form a heavier atom. For his research, Tjayadi focused on the fusion of deuterium and tritium, another hydrogen isotope. This reaction leads to a helium nucleus and massive amounts of energy. The extremely hostile fusion environment, characterized by high heat flux, high temperature and high flux of particles, imposes tremendous challenges to the materials. 

“The retention of large hydrogen isotopes in the structural materials of fusion reactors is not desired, since it results in safety issues and increases the difficulty of realizing the fusion fuel cycle,” Tjayadi explained. “Therefore, our experiment serves to understand the trapping capability of various defect features in advanced steels used in fusion reactors.”

In addition to his research on deuterium in advanced steels, Tjayadi evaluated the hermeticity of silicon carbide (SiC) for use in containing fuel in light water reactors. Hermeticity, in this case, refers to the state of something being airtight. Silicon carbide is being considered to replace the current cladding material, Zircaloy, but researchers must first assess the potential for corrosion and cracking. 

ORNL Research Profile: Leonardi Tjayadi

Leonardi Tjayadi chats with Bredesen Center Director Lee Riedinger following Riedinger’s talk at Career Connections Day. (Credit: Carlos Jones)

When not conducting research, Tjayadi enjoyed many professional development opportunities during his NESLS internship. Among them was Career Connections Day, an event in which ORNL staff members and others discussed their career paths and offered guidance to aspiring researchers. Tjayadi also participated in Professional Organizations Day at ORNL, which gave him the chance to connect with various organizations and learn which group best suited his research field. Additionally, he attended several seminars related to the nuclear field throughout his appointment.

“The NESLS internship experience was more than just daily experiments to produce research results,” Tjayadi said. “It also expanded my professional network and gave me a bigger picture of research life from the sharing of other professionals in the field.”

Tjayadi will continue to pursue his doctoral degree in nuclear engineering at NC State, and he hopes to join ORNL one day as a full-time staff member. 

“I would recommend the NESLS internship program to others as it gives students the opportunity to perform world-class research, gaining new skills and experiences, while the research results benefit the nuclear community and the U.S.,” he said. “This is a win-win solution.”

The NESLS program is administered by the Oak Ridge Institute for Science and Education (ORISE) for the U.S. Department of Energy.

ORNL Research Profile: Leonardi Tjayadi
At the end of his appointment, Leonardi Tjayadi presented his research findings during a poster session for participants in the Nuclear Engineering Science Laboratory Synthesis Program. (Credit: Carlos Jones)