Advancing Nuclear Reactor Safety and Innovation — Drs. Masahiro Kawaji and Taehun Lee

by Malina Seenarine

For the past 60 years, nuclear power has contributed to provide almost 20% of the electricity generated in the United States. 

Although relatively safe, any severe damage caused to the current design of the nuclear reactor — which uses uranium fuel to produce heat and, ultimately, electricity — in nuclear power plants can harm communities and disrupt power supply.  

At the forefront of research to improve the safety of future nuclear reactors is City College’s Masahiro Kawaji and Taehun Lee from the Mechanical Engineering Department at The Grove School of Engineering. 

The nearly 440 nuclear reactors in the world are mostly Light-Water Reactors, meaning that they use water to remove heat from the reactor core. If the coolant, the water, is lost from the reactor system, the nuclear fuel will heat up, increasing the risk of an accident. If electricity is lost at a plant, safety equipment, such as the pump used to inject water into the reactor, will no longer work. This is what happened in the Fukushima Nuclear Disaster in 2011 due to the Tōhoku earthquake and tsunami in Japan.

The U.S. government has spent more than 20 years trying to create advanced nuclear reactors; Generation Four reactors that are more sustainable, safe, efficient and cost-effective than the previous generation. 

The U.S. Department of Energy provides funding to universities to research advanced nuclear reactors. In the past 12 years, CCNY has received six grants ranging from $800,000 to $1.5 million to perform research and train master’s and doctoral students over several projects. The goal is to train the younger generation of engineers who will have a lot of knowledge about new advanced nuclear reactors.

Kawaji, Lee and their students are focused on developing a high-temperature gas reactor that uses helium as a coolant. This is due to its properties of being nonreactive at high temperatures and its efficiency in transferring heat away from the reactor core. Furthermore, these new gas reactors use TRISO fuel, designed to withstand extremely high temperatures, and can potentially facilitate the process of using high temperature heat to split water into hydrogen and oxygen. Produced in large quantities, hydrogen can be used as a new fuel source, which emits water vapor rather than the carbon dioxide that conventional power plants emit. 

Dr. Masahiro Kawaji

Students working with Kawaji, whose focus is on experimental work, participate in constructing basic and advanced apparatus and performing experiments to obtain data. A final report is written and sent to the DOE for publication and the important results are published in journals and presented at conferences. That research is then used to help industry and the National Labs develop advanced nuclear reactors. 

Lee’s focus is more computational and uses advanced computer codes to simulate the experiments. If the simulation matches the experiments accurately, then it is reliable and can eventually be used to predict the performance of an actual nuclear reactor.

The team has to constantly come up with new ideas for research proposals as the grants awarded by the DOE are highly competitive, according to Kawaji. They also collaborate with other universities and the National Labs. 

“We’re collaborating with them so that we’re not sort of stuck to our own ideas alone,” Kawaji said in an interview. “It’s important for our work to be relevant to the industry and what we’re doing is complementary to the National Labs’ reactor development work.”

The team is collaborating with Idaho National Lab, Argonne National Lab and Oak Ridge National Lab. 

In October, Kawaji and Lee will begin a new project funded by DOE and focused on numerical simulations of the experimental data collected in the lab. They will be training new Ph.D. students from the Mechanical Engineering Department in Exascale Computing using an advanced computer program, Nek5000/RS, and the newest supercomputer system at Argonne National Lab. They will also be collaborating with Purdue University and the University of New Mexico, where their students will also be running simulations based on the data from CCNY’s lab.

Kawaji noted that after the students graduate, their skills will be in great demand by the industry, DOE and National Labs.

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