Greg Piefer

Founder and CEO SHINE Technologies

Last Reviewed: September 24, 2026

Executive Summary

Greg Piefer is the founder and CEO of SHINE Technologies, a Janesville, Wisconsin company that builds fusion-based neutron sources and sells what they make possible today, from medical isotopes to materials testing, while working toward fusion energy. His premise, set out in the company’s founder’s letter, is that fusion can grow organically through commercial applications the way semiconductors and solar did, rather than waiting on a single moonshot breakthrough. SHINE employs nearly 400 people across the United States and Europe and on 1 January 2026 completed its acquisition of Lantheus’ SPECT nuclear medicine business. Piefer holds a PhD in nuclear engineering from the University of Wisconsin-Madison.

Career Highlights

• Founded SHINE, incorporated in 2010 as SHINE Medical Technologies; he signed its 2011 Form D as Chief Executive Officer, Secretary and a Director.
• Agreed in May 2025 to acquire Lantheus’ SPECT business, including a manufacturing facility in North Billerica, Massachusetts; Lantheus reports the sale closed on 1 January 2026.
• SHINE says it was the first non-utility since 1985 to reach completion of the Nuclear Regulatory Commission’s technical review of an operating licence application, in 2023.
• Served as a director of Phoenix Nuclear Labs, according to its 2015 Form D.
• Holds a PhD in nuclear engineering and BS degrees in physics and in electrical and computer engineering from the University of Wisconsin-Madison.

Professional Journey

Piefer’s interest in nuclear fusion began in childhood, and he pursued it through the fusion technology programme at the University of Wisconsin-Madison, where he earned BS degrees in physics and in electrical and computer engineering and a PhD in nuclear engineering.

He founded SHINE, incorporated in 2010 as SHINE Medical Technologies, and as chief executive signed its 2011 Form D, reporting $1.4 million raised. The founding idea, as he describes it, was to treat fusion not as a distant energy source but as a technology that could earn its way forward: choose products where fusion has a real advantage, that solve important problems at scale, and that move the company closer to fusion power, and rank them by unit economics rather than market size. The first such product was medical isotopes, notably molybdenum-99, the parent of the most widely used diagnostic imaging isotope, and lutetium-177 for cancer therapy. SHINE has since added neutron testing services, work on nuclear fuel recycling, and a fusion energy programme. The company says that in 2023 it became the first non-utility since 1985 to reach completion of the NRC’s technical review of an operating licence application.

Piefer has also been connected with Phoenix Nuclear Labs, a Wisconsin neutron-generator company: its 2015 Form D lists him as a director alongside Ross Radel, then Phoenix’s president and now SHINE’s chief technology officer. SHINE’s site links to Phoenix’s neutron imaging business.

In May 2025 SHINE agreed to buy Lantheus’ SPECT business, which makes diagnostic imaging agents and includes a manufacturing site in North Billerica, Massachusetts. Lantheus reports the sale closed on 1 January 2026, and SHINE now runs the business as SHINE SPECT with its own chief executive. SHINE’s operating company is a subsidiary of Illuminated Holdings, Inc., whose April 2025 Form D reported $122.5 million raised in a $125 million offering, and on which Piefer serves as an executive officer and director.

Education

University of Wisconsin-Madison

PhD, Nuclear Engineering

University of Wisconsin-Madison

BS, Physics; BS, Electrical and Computer Engineering