Ph.D. student conducts research in nuclear reactor modeling, simulation at ORNL, leading to full-time role
In high school, Yuqiao “Joy” Fan, Ph.D., developed a passion for science as well an appreciation for the environment. Around this time, she learned about the impact of emissions from coal power plants in her community on air quality and human health. This increased awareness inspired her to choose nuclear engineering as her major in college, with the goal of helping advance efforts to reduce emissions and create a safe and green future through nuclear energy.
Connecting with ORNL
While pursuing her doctoral degree in nuclear engineering at North Carolina State University, Fan grew familiar with the U.S. Department of Energy’s Oak Ridge National Laboratory (ORNL) through the university’s involvement in the ORNL-led Consortium for Advanced Simulation of Light Water Reactors (CASL) initiative. Based at ORNL, CASL was an integrated research center that worked to predict the performance of existing and next-generation commercial nuclear reactors through comprehensive, science-based modeling and simulation. The consortium wrapped up its 10-year mission in June 2020.
Through CASL, Fan began a collaboration with W. David Pointer, Ph.D., head of ORNL’s Advanced Reactor Engineering and Development Section. Looking to continue her research in computational fluid dynamics in nuclear reactors, Fan applied and was accepted for an internship appointment at ORNL in fall 2019.
Studying heat transfer in reactors
In light water nuclear reactors, if severe accidents happen, the water in the reactor core will boil and generate steam, Fan explained. One of CASL’s goals was to develop computer simulation capabilities to better predict these boiling conditions, improving both efficiency during normal operations and safety during extreme events.
To this end, the consortium developed a suite of models to help predict the heat transfer in boiling flows, which then inform if the reactor can be cooled down. Prior to Fan’s internship, CASL constructed and validated models for applications in the low-steam fraction flows found in light water nuclear reactors. CASL hoped to extend these models to higher-steam fraction flows, and Fan focused on these during her internship.
Under Pointer’s mentorship, Fan developed an understanding of the CASL boiling models, learned about the code for implementing these models in simulations, improved the simulation setups and conducted simulations with the models. After comparing the simulation result with existing experimental data, she quantified the uncertainty of the model predictions. She also improved the code to be more physically and mathematically accurate to represent boiling flows, and documented the first user guide of CASL boiling models for potential future users.
For Fan, the ORNL internship opened her eyes to the real-life applications of her doctoral research.
“It was the first time that I had escaped from the metaphorical ivory tower, and it was the first time that I began to have a big picture of CASL’s work,” she said. “It was also the first time I felt my Ph.D. research was valuable. The experience of diagnosing research problems as well as looking for solutions was a great adventure.”
Joining ORNL full-time
After her internship, Fan returned to North Carolina State University to complete her doctoral degree and, in February 2022, joined ORNL’s Fusion Energy Division as an associate R&D staff member. In this role, she will focus on fusion reactors, helping develop new and applying existing models and simulation tools to understand liquid metal flows in the fusion blanket and fusion fuel cycle processes, and their design optimization.
Fan credits her internship experience in large part with helping her land the full-time position, and she encourages other students to explore similar research opportunities at federal facilities such as ORNL.
“I gained lots of confidence during my ORNL internship, and I realized that I have the ability and perseverance to conquer any problem in my research,” she said. “This internship experience strengthened me, and I used it as a huge motivation to complete my Ph.D. and to start a new career path.”
The ORNL Educational Programs are managed by Oak Ridge National Laboratory and administered by the Oak Ridge Institute for Science and Education (ORISE).