The Spectrum of Nuclear Energy Innovation

12 Pages Posted: 7 Aug 2023

See all articles by Florian Metzler

Florian Metzler

Massachusetts Institute of Technology (MIT)

Jonah Messinger

University of Cambridge; The Breakthrough Institute

Date Written: June 1, 2023


After many years of stagnation, a new wave of nuclear energy innovation is well underway. Numerous public and private research groups are putting forth a variety of fission and fusion concepts, typically advertising their particular approach as the most superior one, most suitable for large-scale deployment. It can be difficult for observers to evaluate such claims and to situate the promises and remaining uncertainties of each approach in relation to others. Here we propose a "spectrum of nuclear energy innovation" as a framework to compare and contextualize different nuclear innovation efforts. The spectrum is defined by a variable that captures the amount of radioactive materials involved and its release potential, which decreases across approaches as associated physics and engineering uncertainties increase. One end of the spectrum is marked by existing nuclear fission concepts, where innovation efforts are focused on improved cost and safety. The other end of the spectrum is marked by proposed small-scale fusion approaches with the promise of little or no radioactive products but with substantial remaining physics and engineering uncertainty. We suggest that all fission and fusion approaches can be situated along this spectrum. Since to date no clear convergence has occurred toward any particular project or region along this spectrum, we call for a portfolio approach to nuclear energy innovation. Stakeholders should support – and prepare for – a broad range of possible outcomes – as physics, engineering, and economic uncertainties reduce over time and reveal optimal solutions for different nuclear energy applications.

Keywords: nuclear energy; innovation; fission; fusion; energy policy

Suggested Citation

Metzler, Florian and Messinger, Jonah, The Spectrum of Nuclear Energy Innovation (June 1, 2023). Available at SSRN: or

Florian Metzler (Contact Author)

Massachusetts Institute of Technology (MIT) ( email )

77 Massachusetts Avenue
50 Memorial Drive
Cambridge, MA 02139-4307
United States

Jonah Messinger

University of Cambridge ( email )

Trinity Ln
Cambridge, CB2 1TN
United Kingdom

The Breakthrough Institute ( email )

Berkeley, CA
United States

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