Founder of SHINE Technologies, pioneering commercial fusion neutron applications from medical isotopes to defense and industrial inspection
Greg Piefer is the founder and chief executive officer of SHINE Technologies, a Janesville, Wisconsin-based company that has built one of the first commercially operating fusion-based facilities in the world. Rather than pursuing electricity generation, Piefer recognized early that fusion neutrons have enormous near-term commercial value in medical isotope production, industrial inspection, and defense applications—markets that could be served by sub-breakeven fusion devices operating reliably at industrial scale.
Piefer developed the foundational concept for SHINE while pursuing his graduate studies in nuclear engineering at the University of Wisconsin–Madison under Gerald Kulcinski, a pioneer in helium-3 fusion and lunar resource utilization. Piefer’s insight was that a deuterium-tritium fusion neutron source, even one far below energy breakeven, could produce neutron fluxes sufficient to transmute targets into valuable isotopes—most notably molybdenum-99 (99Mo), the parent isotope of technetium-99m, which is used in over 40 million medical diagnostic imaging procedures annually worldwide.1
The global supply of 99Mo has historically depended on a small number of aging research reactors, several of which have experienced unplanned shutdowns that caused supply crises affecting hospitals and patients. SHINE’s approach replaces reactor-based production with an accelerator-driven fusion neutron source: deuterium ions are accelerated into a tritium target, producing 14.1 MeV neutrons that irradiate a low-enriched uranium solution to generate 99Mo. This process avoids the proliferation concerns associated with highly enriched uranium targets used in legacy reactor production.2
SHINE’s production facility in Janesville received its operating license from the U.S. Nuclear Regulatory Commission, making it one of the first privately built and licensed fusion-based nuclear facilities. The plant houses multiple neutron-generating units and a full radiochemical processing line capable of extracting, purifying, and shipping medical isotopes to hospitals and radiopharmacies. The licensing process itself was a significant achievement, establishing regulatory precedents for commercial fusion devices.3
Beyond medical isotopes, Piefer has expanded SHINE’s portfolio into industrial non-destructive inspection and defense applications. The company’s neutron sources can image the internal structure of complex assemblies—jet engine turbine blades, munitions, and aerospace components—with a penetrating power that X-rays cannot match. SHINE has also pursued contracts for nuclear waste recycling and material processing using neutron irradiation.4
Piefer’s career demonstrates that fusion technology need not wait for energy breakeven to deliver commercial and societal value. By targeting the neutron rather than the kilowatt-hour, SHINE has built a profitable, operating fusion-based business while the rest of the industry continues working toward net energy.