Director, UMD Nuclear Reactor & Radiation Facilities
From 2013 to 2019, Tim Koeth served as Director of the University of Maryland Nuclear Reactor and Radiation Facilities, overseeing the 250-kW Maryland University Training Reactor (MUTR), Cobalt-60 gamma irradiation facilities, and electron linear accelerators. Tim did not merely administer an existing reactor facility; he helped preserve it when its future was uncertain and broadened its mission into a multidisciplinary research, education, and training resource.
For Tim, the opportunity also had unusual personal significance. From the age of ten, he had dreamed of building a nuclear reactor. Decades later, taking responsibility for UMD’s reactor and helping to revitalize its facilities became, in a sense, the fulfillment of that boyhood ambition. Rather than building a reactor from the ground up, he had the opportunity to metaphorically “rebuild” an existing one—renewing its purpose, modernizing its capabilities, and helping secure its future for another generation of students and researchers.
A major achievement of Tim’s tenure was securing the long-term future of the MUTR. The reactor’s relicensing was itself a generational undertaking: the process had begun in 1999 under Tim’s predecessors, many years before he became director. Tim inherited their work and had the honor of bringing the long regulatory effort to completion. Following the extensive Nuclear Regulatory Commission review process, the MUTR received a renewed operating license for an additional 20 years, preserving one of the relatively few university research reactors remaining in the United States.
Tim has likened the experience to the generations of craftsmen who built the great cathedrals: most labored knowing that others would someday complete what they had begun, while one fortunate generation ultimately had the satisfaction of placing the spire on top. Tim’s role in the MUTR relicensing was much the same. He did not begin the effort, and its success rested upon years of work by the directors, reactor staff, university officials, and others who came before him. But as director, he had the privilege—and responsibility—of carrying that accumulated work across the finish line and seeing the reactor’s future secured.
Giving the Reactor New Fuel—and New Life
Securing the reactor’s license, however, solved only part of the problem. The MUTR was still operating with essentially the same TRIGA fuel that had been loaded into its core in 1974. By Tim’s directorship, that fuel was nearing the end of its useful operating life. Although the reactor was licensed for 250 kW, the depleted original core could reach only about 180 kW, and could do so only intermittently. The increasingly ambitious research, teaching, and operator-training programs being developed at Maryland required the reactor to operate at full power and with much greater regularity.
The obvious solution of buying new fuel was not available. At the time, new TRIGA fuel simply could not be purchased. Instead, Tim and UMD worked with the U.S. Department of Energy on an unprecedented alternative. Lightly used TRIGA fuel existed in storage at DOE’s Idaho Nuclear Technology and Engineering Center. Rather than leave this still-useful material consigned to waste storage, DOE proposed recovering suitable fuel elements and returning them to productive reactor service at Maryland.
It became a first-of-its-kind fuel replacement. A new policy initiative was created within DOE’s Office of Nuclear Energy and approved by the Nuclear Regulatory Commission, allowing lightly used TRIGA fuel to be taken out of storage and placed back into service. DOE had identified the University of Maryland as the research reactor in the United States with the greatest need for fuel. In March 2017, the MUTR was refueled with the recovered fuel from DOE’s Idaho site.
Tim described the solution as a form of nuclear “recycling,” but its significance went beyond simply obtaining fuel for one university reactor. For the first time, DOE had established a pathway for usable research-reactor fuel that had been placed into storage to be recovered and returned to productive service. In Maryland’s case, the result helped give an aging reactor a renewed operational life and provided the capability necessary to support the expanded research and educational mission that Tim and his colleagues were building.
Tim and his team also expanded the reactor’s experimental capabilities, including development of a neutron-imaging facility that opened new applications ranging from materials research to studies involving the preservation of cultural artifacts. The investments in the reactor during this period specifically supported new research capabilities, including neutron imaging, as well as classes and undergraduate reactor-operator training.
This image above records the first neutron radiograph produced during the inaugural neutron-imaging session at the University of Maryland Research Reactor (MUTR) in 2015. As a demonstration of neutron radiography’s unusual imaging properties, a collection of everyday objects was mounted on a ¼-inch-thick sheet of lead: plastic letters spelling “UMD MUTR 2015,” a nylon gear, nylon bolt, nylon zip-tie, and a section of stranded copper wire clad in PVC insulation.
Unlike conventional X-ray imaging, neutron radiography does not simply highlight the densest or heaviest materials. Neutrons interact strongly with certain light elements—particularly hydrogen—while penetrating many dense metals comparatively well. Consequently, the hydrogen-rich plastics and nylon components are readily visible, even though they were imaged through the lead sheet. The PVC insulation surrounding the stranded copper wire is also clearly delineated.
Beyond being a useful first test of the imaging system, the radiograph marked an important expansion of MUTR’s experimental capabilities: the reactor was now being used not only as a neutron source for irradiation and research, but as a tool for nondestructive neutron imaging.
The Rose Inside a Lead Can — Neutron Imaging
Tim Koeth holds the rose and ¼-inch-thick lead container immediately before placing the experiment into the neutron-imaging station at the University of Maryland Research Reactor (MUTR). The rose would be inserted inside the lead cylinder and positioned in the neutron beam to demonstrate a striking property of neutron radiography: neutrons can penetrate the dense lead while strongly revealing the hydrogen-rich organic material of the flower concealed within it.
Visible in the foreground is the shielded neutron-imaging station where the experiment would be positioned for exposure. The resulting radiograph fulfilled a long-standing personal “bucket-list” experiment for Tim—using the reactor’s neutron beam to quite literally see a rose through lead.
These three images provide a striking demonstration of one of the unusual capabilities of neutron radiography. At left, a rose is placed inside a cylindrical container surrounded by approximately ¼-inch-thick lead walls. The center image shows the assembly radiographed using a conventional 150 kVp X-ray source. The dense lead strongly attenuates the X-rays, leaving essentially only the silhouette of the container—the rose hidden inside cannot be seen.
The neutron radiograph at right produces a dramatically different result. Neutrons penetrate the lead comparatively readily while interacting strongly with the hydrogen-rich water and organic material of the flower. The result is almost the reverse of the X-ray image: the lead container becomes relatively transparent, revealing the rose concealed within it, including the flower head, stem, and portions of its leaves.
Hands-On Nuclear Education
Tim worked to make the Radiation Facilities useful well beyond the traditional boundaries of nuclear engineering, with hands-on education becoming a particularly important part of his vision for the facility. During his directorship, Tim established UMD’s Undergraduate Reactor Operator Program, creating a pathway for undergraduate students to move beyond classroom instruction and learn the operation of an actual nuclear research reactor.
Students could gain practical experience with reactor physics, instrumentation, radiation protection, operating procedures, and the disciplined safety culture required for reactor operations, with the opportunity to progress toward reactor-operator qualification and licensing. The program embodied Tim’s belief that some aspects of nuclear science and engineering are best learned not simply from equations or textbooks, but by giving students meaningful responsibility for real scientific equipment. The contemporary account of the reactor’s revitalization specifically identifies infrastructure upgrades supporting the undergraduate reactor-operator training program alongside classes and new research capabilities.
More broadly, undergraduate and graduate students gained hands-on experience with reactor operations, neutron and gamma irradiation, electron accelerators, radiation measurement, and experimental nuclear science. At the same time, the facilities supported researchers from multiple disciplines within UMD as well as collaborations with outside organizations.
The facility also became an important foundation for Tim’s own research. Using its electron accelerators, he developed research into radiation effects on materials, work that grew into a broader program investigating the behavior of materials in extreme radiation environments.
After completing his term as director in 2019, Tim remained closely involved with the Radiation Facilities and today serves as Director of Research, as well as Chair of UMD’s Radiation Safety Committee and Reactor Safety Committee.
Preservation and Transformation
Tim’s directorship ultimately represented both preservation and transformation: preserving a unique piece of UMD’s nuclear infrastructure at a time when its continued future was not assured, while transforming its mission from that of a traditional university training reactor into a broader multidisciplinary resource for radiation science, materials research, education, and hands-on experimentation.
In several important respects, the pieces reinforced one another. A 20-year NRC license secured the reactor’s regulatory future; the first-of-its-kind DOE fuel recovery helped secure its operational future; and new capabilities, including neutron imaging and the Undergraduate Reactor Operator Program, helped secure its scientific and educational future. The contemporary Nuclear News account captured the objective Tim had been given when he became director: to transform the facility into a “world-class research and teaching facility,” even though UMD’s nuclear engineering program had gone dormant.
In doing so, the ten-year-old who once dreamed of building a nuclear reactor ultimately found himself responsible for something perhaps more consequential—helping ensure that an actual university reactor would continue operating, teaching, and enabling discovery for decades to come.
