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The Value and Cost of Fusion Neutrons

J. F. Parisi, K. Schiller

Abstract

Deuterium-tritium fusion reactions produce high-energy neutrons that can transmute materials into valuable isotopes. Over the next ten years, the cost of fusion neutrons is projected to decrease by roughly seven orders of magnitude. Most ($\sim$5 orders of magnitude) is technological overhang driven by the low availability of current experiments; the remaining $\sim$2 orders of magnitude require higher plasma gain and lower capital intensity. We introduce the levelized cost of a neutron (LCON), an economic metric analogous to the levelized cost of energy that gives the minimum neutron value for economic breakeven of a fusion system. LCON depends on plasma gain, capital intensity, availability, and neutron flux, and is offset by revenue from co-produced electricity, precious metals, and radioisotopes. The revenue per neutron spans at least ten orders of magnitude, from electricity and gold ($\sim$\$$10^{-20}$/neutron) to actinium-225 ($\sim$\$$10^{-10}$/neutron), defining a `neutron ladder': a staged, revenue-positive development pathway from current fusion devices to terawatt-scale power plants.

The Value and Cost of Fusion Neutrons

Abstract

Deuterium-tritium fusion reactions produce high-energy neutrons that can transmute materials into valuable isotopes. Over the next ten years, the cost of fusion neutrons is projected to decrease by roughly seven orders of magnitude. Most (5 orders of magnitude) is technological overhang driven by the low availability of current experiments; the remaining 2 orders of magnitude require higher plasma gain and lower capital intensity. We introduce the levelized cost of a neutron (LCON), an economic metric analogous to the levelized cost of energy that gives the minimum neutron value for economic breakeven of a fusion system. LCON depends on plasma gain, capital intensity, availability, and neutron flux, and is offset by revenue from co-produced electricity, precious metals, and radioisotopes. The revenue per neutron spans at least ten orders of magnitude, from electricity and gold (\10^{-10}$/neutron), defining a `neutron ladder': a staged, revenue-positive development pathway from current fusion devices to terawatt-scale power plants.
Paper Structure (1 section, 19 equations, 4 figures, 2 tables)

This paper contains 1 section, 19 equations, 4 figures, 2 tables.

Table of Contents

  1. Appendix: Derivation of LCON

Figures (4)

  • Figure 1: (a) Effective LCON versus $Q$ at $I^\mathrm{cap} = \$2$ B/GW and $\mathcal{A} = 1$. Blue curves: $\mathrm{LCON}^\mathrm{elec}$ at $C_e = \$50$/MWh$_e$ (solid) and $\$100$/MWh$_e$ (dashed), with electricity-only breakeven at $Q \approx 22$ and $\approx 10$, respectively. Orange: $\mathrm{LCON}^{\mathrm{elec+gold}}$ at $\$50$/MWh$_e$, with gold co-generation reducing breakeven to $Q \approx 3$. Green shading: profitable region. (b) LCON and revenue per MWh$_e$ (at $50/MWh$_e$) versus gold price at $Q = 20$; blue lines show $\mathrm{LCON}^\mathrm{elec}$ at both electricity prices.
  • Figure 2: Levelized cost of a neutron for electricity only (LCON$^\mathrm{elec}$, solid) versus plasma gain for six capital intensities at $C_e = \$100$/MWh$_e$ and $\mathcal{A} = 1$. Dashed horizontal lines: value per neutron $v_\mathrm{n}$ for transmutation products. A product is profitable where its $v_\mathrm{n}$ line lies above the LCON$^\mathrm{elec}$ curve. Green shading: profitable region where LCON$^\mathrm{elec} < 0$ (electricity revenue alone exceeds all costs). Standard parameters from parisi2025isotope.
  • Figure 3: Levelized cost of a neutron for $\ce{^99Mo}$ production, LCON$^{\mathrm{elec}+\ce{^99Mo}}$. We used $Q=0.01$, $I^\mathrm{cap}= \$2$B/GW, $\mathcal{A} = 1$, $\sigma = 20$mb. Nominal cost of unenriched ruthenium: $C_\mathrm{feed}=\$12$/g. Green shading indicates the profitable region.
  • Figure 4: Neutrons per dollar versus neutron rate for entire market for a range of transmutation products. ARC Sorbom2015 vertical line assumes 100% availability factor.