On the Next Frontier

Like every college campus, there are official and unofficial routes around the Grainger Engineering campus. Marked by worn lines in the grass, one of these unofficial paths borders an unassuming parking lot at the back of the Materials Research Lab. It’s a shortcut for students traveling between the Grainger Engineering Library and their Urbana apartments. Few take a moment to read the placard that informs them that they are walking over history.

Spring 2021

Meeting a Nuclear Moment

What is now one of the few empty spaces on a booming campus was once the site of a nuclear reactor. While this storied TRIGA reactor might have lost its physical place, it’s place in Illinois and nuclear research history is forever etched into campus history.

Officially known as the University of Illinois Advanced Teaching Research Isotope General Atomic (TRIGA Mark II) Reactor, it was used to train students in nuclear engineering and to provide a place for onsite nuclear research.

At the October 22 dedication in 1960, David D. Henry, president of the university at the time, called TRIGA’s addition to the campus “both a compliment to the past record and a promise for the future.”

Futuristic it was. The campus newspaper “The Daily Illini” described it in December 1960 as looking “like something from a science-fiction movie.”

TRIGA was accessed from a room deep below ground. A catwalk ran atop an eight-sided structure. A 16-foot-deep tank of water was covered by a grate. Under all that water was the reactor’s core, a cylinder about 15 inches high and 15 inches in diameter. The tank holding the core was also surrounded by 7 and a half feet of cement.

Safety topped the community’s concerns about installing a nuclear reactor meant to train students. Because TRIGA was built with the relatively inexperienced user in mind, the risks were low.

As only the second such reactor on a college campus, this TRIGA reactor served as model for other universities looking to install their own.

Cornell University’s D.D. Clark was on hand for the TRIGA dedication as he began planning the installation of a similar reactor on his home campus and said the only way harm would come to the Illinois campus by way of the TRIGA reactor would be “nothing short of sabotage or dynamite.” The fuel elements of the reactor were self-limiting, so whenever output rose above normal, it was automatically cut back.

“This type of reactor has the moderator (which slows the neutrons) built into the reaction material. This, with the general ‘fail-safe!’ design makes it impossible for the students working with the reactor to hurt anyone,” Clark said to The Daily Illini.

Clark was right. Generations of students went on to use the reactor without incident and became leaders in the nuclear field with a jump start on their peers from other institutions.

“The reactor facility was vital in the masters’ and/or doctoral theses of approximately 600 NPRE graduate students, and was a teaching tool for a host of the department’s undergraduates,” said former Reactor Administrator Rich Holm. Holm was a student in the college’s nuclear program and was a senior active reactor operator while earning his NPRE master’s degree in 1990.

“Virtually every NPRE student between 1960 and 1998 used the TRIGA reactor,” Holm told the college in 2011.

The prospect of working on TRIGA was enticing for prospective students and faculty alike. A tour of the reactor was one of the most popular stops for visitors to Engineering Open House, an annual event that invites community members to see the innovations happening at the college.

Access to TRIGA sparked Emeritus Professor George Miley’s more than four-decade career at the University.

“The existence of the new TRIGA reactor… was an important factor that convinced me to join the Nuclear Engineering faculty in 1961,” Miley said. “Indeed it worked out that I was able to do considerable research that was enabled by having the TRIGA on campus.”

As time went on, access was not limited to students and academics. Scores of nuclear industry reactor operators trained on the facility, and thousands of visitors touring the TRIGA learned first-hand about the importance of nuclear energy and safety.

Research Advances

Training was not the reactor’s sole use. The University’s TRIGA reactor was fundamental in numerous discoveries in fields that went on to improve the functioning of existing fission reactors, advancements in medical diagnostics and procedures, and general fundamental understanding of the field.

More specifically, researchers used the reactor for a decade of work on fission fragment physics and added fundamental data on this fundamental process.

Several decades of studies of nuclear-pumped lasers accomplished the discovery of the second such laser reported. This was followed by six additional new types of lasers. Separate studies also demonstrated a kV level nuclear battery.

Researchers also used the reactor for studies of nuclear reactor kinetics including the first experimental study and associated theory for rapid repetitive pulsing by a TRIGA. Additionally, TRIGA research resulted in state-of-the-art neutron activation analysis for ultra low concentration of airborne radioisotopes and other contaminants. It also allowed for the production of radioisotopes for use in animal studies by members of the College of Veterinary Medicine.

The University’s TRIGA reactor was also home to plenty of firsts, including the first experimental theoretical study of neutron pulse propagation through the graphite thermal column.

This groundbreaking research was made possible by consistent and considerable upgrades on the reactor during its active years.

The original reactor core was capable of 30-40 ms pulses of 1,000 megawatts, with a 100 kW licensed steady operating power. This was a good amount for basic education and some research, but additions and increased power over time allowed for more influential research.

The addition of a cooling tower a few years after the facility’s commissioning allowed an increase in steady-state operation to one megawatts. This, combined with the internal core flux trap, allowed the highest steady-state neutron flux operation of a university TRIGA.

In 1968, the University approved upgrading the reactor and increasing its steady peak power to 1.5 megawatts or more, while making it capable of pulsing up to 6,000 megawatts.

TRIGA was equipped with a “through port” that passed by the end of the reactor core and penetrated the shield of the opposite sides. This later allowed important studies of nuclear-pumped lasers, since beam alignment was enabled. TRIGA provided access to a central core pump trap (enabling experiment requiring high neutron fluxes during either steady state or pulsing) and a “rabbit tube” passing through the core to provide rapid insertion and removal of samples for irradiation studies.

A graphite thermal column led from the TRIGA core into the “bulk shielding tank,” a large water tank located next to the main TRIGA water tank. This enabled studies of both steady-state and pulsed neutron studies of objects located in the bulk shielding tank. Most notable was the Low Power Reactor Assembly (LOPRA) reactor core. This facility allowed a series of coupled core reactor experiments that provided basic data for large-power reactor kinetics.

The reactor was not limited to use by students and researchers in the nuclear engineering program.  Departments like chemistry, chemical engineering, physiology, biophysics, physics, and others from around engineering took advantage of the research and educational possibilities.

This heavy interest in the reactor made it a true campus hot spot for nearly 40 years.

Decommissioning and Legacy

The university’s TRIGA reactor’s fate was tied to attitudes about nuclear power and research in the country.

Its rise came as the world was just beginning to dip its toe into the waters of potential for nuclear power.

As the country entered the 1990s, the tides began to turn on nuclear energy. As a result, enrollment in nuclear engineering programs dipped and federal support for nuclear research projects was rolled back.

Many universities decided to pull the plug on their reactors. Illinois was no different. In 1998 the beloved TRIGA Mark II was shut down. The fuel was removed in 2004, and physical reminders of the reactor began to fade into the campus shadows.

Although faded, the TRIGA reactor was far from forgotten. In 2015, the American Nuclear Society gave it a National Nuclear Landmark designation for its impact on both education and research.

“Generations of NPRE students were able to enjoy the unique experience of operating and experimenting with our TRIGA reactor,” said Professor Jim Stubbins, former head of the Nuclear, Plasma, & Radiological Engineering Department when the designation was announced. “Our TRIGA was really unique since many of the features were designed by our faculty to provide major experimental and operational features not available with other TRIGA reactors.”

The Nuclear, Plasma, & Radiological Engineering Department has maintained its reputation as one of the nation’s best that it gained when TRIGA was running. In the more than 20 years since its decommissioning, there has been a renewed interest in adding a reactor to the campus toolbelt once again.

It has been nearly 30 years since a new nuclear reactor has been built on any college campus, but the push for research into clean, sustainable energy solutions and for campus carbon neutrality in higher education could provide a needed push to begin a new generation.

The next generation of reactors on university campuses can target a broad research portfolio, focused on synergistic technologies for a clean and sustainable energy future, according to Caleb Brooks, a professor in the Grainger Engineering Nuclear, Plasma, & Radiological Engineering Department.

“We’ve already identified many opportunities across campus, including work on clean water, instrumentation and control, micro-grid technology, cybersecurity, hydrogen production for transportation and energy storage, and many others,” Brooks said. “The number of great, world-changing projects that a micro-reactor could make possible over the coming years though leveraging these strength areas of UIUC is enormous. “

The University of Illinois Urbana-Champaign is committed to becoming carbon neutral by 2050, and The Campus Master Plan and Illinois Climate Action Plan in 2015 identified that Advanced Small Modular Reactors are one potential clean energy solution for campus. The latest 2020 version of the plan also alludes to the possibility of harnessing nuclear power.

In 2015, such reactors were not available commercially. In the nearly six years since, the technology has matured rapidly, and the possibility of bringing what is now known as a micro-reactor to campus seems a much more reasonable reality.

“Beyond the research potential we plan for this reactor to demonstrate clean and sustainable 

power production through integration with our campus power plant, and provide a training and education resource to train the future clean energy workforce,” Brooks said. “It would be a win for energy-related education and research campus wide, and for campus sustainability efforts.”

What is TRIGA

TRIGA (Training, Research, Isotope Production General Atomics) reactors were conceived in the late 1950s. Developed by General Atomics, the first TRIGA reactor went critical in 1958 in San Diego at the company’s campus, and 66 were eventually built in 23 countries. Initially popping up mainly in the US and Europe, they were later used in Asia and Latin America as well. Like the TRIGA reactor on the Illinois campus, many were used for training and education, but some were also used in hospitals for radioisotope production.

The concept was devised at a large international conference in 1955 in Geneva, Switzerland. One of the American organizers of the conference was Frederic de Hoffman, a nuclear physicist who worked at General Dynamics Corporation. He returned to the states and convinced his bosses of the need to develop commercially available nuclear reactors.

Over the years, three versions of the TRIGA reactor were developed. The TRIGA Mark I was below-ground and extremely simple to construct. Special containment or confinement was not necessary, and they could even be installed in existing buildings.

Over the years, three versions of the TRIGA reactor were developed. The TRIGA Mark I was below-ground and extremely simple to construct. Special containment or confinement was not necessary, and they could even be installed in existing buildings.

TRIGA Mark III reactors provided a movable reactor core, supporting both steady-state and pulsing operations, but with greatly increased operational flexibility.

Since the 1990s, many TRIGA reactors have been decommissioned. Worldwide 38 TRIGA reactors remain operational, and while they are considered “senior age” they’re still going strong.

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