(Idaho National Laboratory Press Release, December 22, 2025; Cover image credit: INL FB)
At approximately 12:55 p.m. Wednesday, May 14, operators and onlookers at the Transient Reactor Test (TREAT) facility control room witnessed history. With an odd, almost kazoo-like sound coupled with a loud beep emitting from instruments in the control room, TREAT completed the United States’ first accident test on spent next-generation nuclear fuel from a commercial reactor. The experiment, over ten years in the making, marks the beginning of a new era in nuclear fuels research.
Overseeing the reactor operations for the pivotal experiment was Ellen Jenkins, a reactor operator training to qualify as a senior reactor operator. Jenkins managed each phase of the experiment, demonstrating a thorough understanding of the process. To Jenkins and her colleagues, this was just another day in the control room.
“The senior reactor operator is communicating back and forth with the reactor operator on the functions and actions that are being performed,” said Jenkins. “You have to be focused on many different indications to make sure the reactor runs as you intend and be ready to take action whenever something happens that isn’t intended.”
On Sept. 15, Jenkins passed her qualifying oral exams, becoming TREAT’s first ever female senior reactor operator.
Revitalizing TREAT: A new mission for a historic reactor
TREAT is a powerful test reactor designed to push materials to their breaking point. It applies controlled-short term bursts of intense neutron flux, called transients, toward fuel and material specimens to simulate accident scenarios.
Since it began operations in 1959, researchers have used the reactor to test the performance of fuels and materials in a variety of projects and experiments. The reactor was placed in standby mode in 1994, but in 2014, laboratory leadership decided to restart the reactor with a more specific mission: to test spent advanced commercial nuclear fuel.
To that end, managers assembled a world-class team of engineers, researchers and operators to run the reactor. By 2017, TREAT officially resumed operations, and Jenkins joined the team in 2023.
Making it to the TREAT control room
Jenkins is the youngest senior reactor operator at TREAT. “It’s a fallacy that some people have – if you’re young, you can’t lead a group of people,” said TREAT operations manager Anthony Maestas. “She’s already becoming a natural leader.”
Born and raised in Rexburg, Idaho, Jenkins grew up on a family farm and attributes her hard-working nature to her upbringing. “It gave me a lot of qualities that, looking back, I really cherish,” said Jenkins. “I learned how to work hard, how to fight for what’s important, and that I’m the only one who can get things that I want through the efforts that I put in.”
As a student, Jenkins had an interest in nuclear science and did well in school, but she didn’t have a career path in mind. However, a high school field trip to the Experimental Breeder Reactor-I Museum changed that. “There were some interns there that were talking about the EBR-I fuel and the program there, and I remember being so inspired,” she said. “At that moment I decided that I’m going to get into this industry.”
From then on, Jenkins focused on courses and leadership roles to build her skill set for the field. In May 2023, she earned an associate degree in energy systems nuclear operations technology from Idaho State University, where she also received the Outstanding Student Award for the College of Technology. During her studies, Jenkins obtained a Nuclear Regulatory Commission reactor operator license in August 2022, allowing her to operate the university’s research reactor. There she gained enough experience to teach underclassmen to operate the reactor. In May 2023, she began an internship at INL with the TREAT organization.
Mastering the role of senior reactor operator
Jenkins recalls her first time running an experiment. “My first transient was a little overwhelming,” she said. “It’s very scripted. There are ways you have to dictate and communicate in the control room, and it’s a lot to remember. So that was a bit of a learning curve in the beginning.”
However, Jenkins rose to the challenge, obtaining her reactor operator and senior reactor operator certifications. “We’re very particular on who can qualify as a senior reactor operator,” said Maestas. “Normally, it’s someone a lot more senior, but Ellen shows the same level of knowledge. Experience will come, but she can command. She knows what she’s doing and can lead small teams.”
As a certified senior reactor operator, “You get to do more than just control room operations,” Jenkins said. “You get to do the entire evolution, from the experiment assembly to taking it out of the core and shipping it for analysis. So, I don’t think I’ll ever be bored here.”
According to Maestas, one of Jenkins’ more complex responsibilities is leading core changes, which are among the most technical processes at the facility. “It’s pretty complicated with many moving parts, like lifting 17,000-pound blocks with cranes,” he said. “People know she’s in charge and she backs it up with the right words and the right knowledge.”
A bright future
Looking to the future, Jenkins hopes to stick around INL. “I definitely see a career here at the lab, hopefully at TREAT, specifically.”
This sentiment is shared by Maestas and TREAT staff members. “One of the things that makes her unique is that no matter who you are or what you do, every person who interacts with Ellen always walks away a better person because of it,” said Maestas.
By Amy Kelley, INL Communications
About Idaho National Laboratory
Battelle Energy Alliance manages INL for the U.S. Department of Energy’s Office of Nuclear Energy. INL is the nation’s center for nuclear energy research and development, and also performs research in each of DOE’s strategic goal areas: energy, national security, science and the environment. For more information, visit www.inl.gov. Follow us on social media: Facebook, Instagram, LinkedIn and X.
