NSE - Nuclear Science & Engineering at MIT


Optimizing construction and operation of nuclear energy facilities

female with arms crossed standing on the right side of the photo inside a building at MIT with a brick wall to the right and steel structure to the left

For the United States to meet its net zero goals, nuclear energy needs to be on the smorgasbord of options. The problem: Its production still suffers from a lack of scale. To increase access rapidly, we need to stand up reactors quickly, says Isabel Naranjo De Candido, a third-year doctoral student under the advisement of Prof. Koroush Shirvan.

One option is to work with micro reactors, transportable units that can be wheeled to areas that need clean electricity. Isabel’s master’s thesis at MIT, supervised by Prof. Jacopo Buongiorno, focused on such reactors.

Another way to improve access to nuclear energy is to develop reactors that are modular so their component units can be manufactured quickly while still maintaining quality. “The idea is that you apply the industrialization techniques of manufacturing so companies produce more [nuclear] vessels, with a more predictable supply chain,” Isabel says. The assumption is that working with standardized recipes to manufacture just a few designed components over and over again improves speed and reliability and decreases cost.

As part of her doctoral studies, Isabel is working on optimizing the operations and management of these small modular reactors so they can be efficient in all stages of their lifecycle: building; operations and maintenance; and decommissioning. The motivation for her research is simple: “We need nuclear for climate change because we need a reliable and stable source of energy to fight climate change,” Isabel says.

A childhood in Italy

Despite her passion for nuclear energy and engineering today, Isabel was unsure what she wanted to pursue after high school in Padua, Italy. The daughter of a physician Italian mother and an architect Spanish father, Isabel enrolled in a science-based high school shortly after middle school as she knew that was the track she enjoyed best.

Having earned very high marks in school, Isabel won a full scholarship to study in Pisa, at the special Sant’Anna School of Advanced Studies. Housed in a centuries-old convent, the school granted only masters and doctoral degrees. “I had to select what to study but I was unsure. I knew I was interested in engineering,” Isabel recalls, “so I selected mechanical engineering because it’s more generic.”

It turns out Sant’Anna was a perfect fit for Isabel to explore her passions. An inspirational nuclear engineering course during her studies set Isabel on the path toward studying the field as part of her master’s studies in Pisa. During her time there, Isabel traveled around the world — to China as part of a student exchange program and to Switzerland and the United States for internships. “I formed a good background and curriculum and that allowed me to [gain admission] to MIT,” Isabel says.

At an internship at NASA’s Jet Propulsion Lab, Isabel met an MIT mechanical engineering student who encouraged her to apply to the school for doctoral studies. Yet another mentor in the Italian nuclear sector had also suggested Isabel apply to MIT to pursue nuclear engineering so Isabel decided to take the leap.

And she is glad she did.

Improving access to nuclear energy

At MIT, Isabel is working on improving access to nuclear energy by scaling down reactor size and, in the case of micro-reactors, making them mobile enough to travel to places where they’re needed. “The idea with a micro reactor is that when the fuel is exhausted, you replace the entire micro reactor onsite with a freshly fueled unit and take the old one back to a central facility where it’s going to be refueled,” Isabel says. One of the early use cases for such micro-reactors has been remote mining sites which need reliable power 24/7.

Modular reactors, about ten times the size of micro-reactors, ensure access differently: by modularizing components so they can be manufactured and installed at scale. These reactors cannot just deliver electricity but also cater to the market for industrial heat, Isabel says. “You can locate them close to industrial facilities and use the heat directly to power ammonia or hydrogen production or water desalinization for example,” she adds.

As more of these modular reactors are installed, the industry is expected to expand to include enterprises that choose to simply build them and hand off operations to other companies. Whereas traditional nuclear energy reactors might have a full suite of staff on board, smaller scale reactors such as modular ones cannot afford to staff in large numbers so talent needs to be optimized and staff shared among many units. “Many of these companies are very interested in knowing exactly how many people and how much money to allocate and how to organize resources to serve more than one reactor at the same time,” Isabel says.

Isabel is working on a complex software program that factors in a large range of variables — from raw materials cost and worker training, reactor size, megawatt output and more. It also leans on historical data to predict what resources newer plants might need. The program also informs operators about the tradeoffs they need to accept: for example, “if you reduce people below the typical level assigned, how does that impact the reliability of the plant, that is, the number of hours that it is able to operate without malfunctions and failures?”

And managing and operating a nuclear reactor is much more complex because safety standards limit how much time workers can work in certain areas and how safe zones need to be handled.

“There’s a shortage of [qualified talent] in the industry so this is not just about reducing costs but also about making it possible to have plants out there,” Isabel says. Different types of talent are needed — from professionals who specialize in mechanical components to electronic controls. The model that Isabel is working on considers the need for such specialized skillset as well as making room for cross-training talent in multiple fields as needed.

In keeping with her goal of making nuclear energy more accessible, the optimization software will be open-source, available for all to use. “We want this to be a common ground for utilities and vendors and other players to be able to communicate better,” Isabel says, “they should be able to talk on the same ground of knowledge.” Doing so will accelerate the operation of nuclear energy plants at scale, Isabel hopes. An achievement that will come not a moment too soon.

VIDEO: Improving access to nuclear energy

Written by Poornima Apte. Video by Jason Kimball. Photo by Gretchen Ertl.

June 2023