Comparative feasibility of deuterium–tritium versus alternative fusion fuels

Determine, through quantitative comparison of engineering requirements and commercialization challenges, whether achieving commercially viable controlled fusion energy is easier via deuterium–tritium fuel—addressing tritium breeding, high‑energy neutron damage to first‑wall and blanket materials, and associated costs—or via alternative fuels such as deuterium–deuterium, deuterium–helium‑3, or proton–boron‑11, which avoid tritium and reduce neutron production but require substantially higher temperatures and stricter radiation management.

Background

The book outlines that deuterium–tritium (D–T) fusion has the lowest ignition temperature and largest low‑energy cross‑section, making it scientifically the easiest to ignite. However, D–T presents serious engineering and commercialization hurdles: tritium’s short half‑life and scarcity necessitate breeding (e.g., via lithium), global tritium production is minimal, and 14‑MeV neutrons cause severe materials damage that current first‑wall structures cannot withstand.

Alternative fuels (D–D, D–3He, p–11B) avoid or greatly reduce tritium use and neutron production, but require significantly higher temperatures, face stronger radiation losses (bremsstrahlung and synchrotron), and demand challenging plasma conditions. The text explicitly states uncertainty about which path is ultimately easier to commercialize, motivating a rigorous comparative assessment.

References

“It is currently uncertain whether it is easier for deuterium-tritium fusion to overcome these engineering and commercialization challenges, or if fusion energy can be achieved more easily through fuels other than deuterium and tritium.”

— Introduction to Fusion Ignition Principles: Zeroth Order Factors of Fusion Energy Research  (2410.18054 - Xie, 2024) in Chapter 2 (Fusion Nuclear Reaction Basics), Section “The main advantages and disadvantages of several fusion fuels”, Subsection “Deuterium-Tritium”

We conclude: rather than the commonly addressed challenge of achieving $dt$-burn, in our opinion the central unsolved challenge of the $dt$-based nuclear fusion reactor energy economy is harnessing the $dt$-reaction energy from the ultra-fast 14 MeV neutrons and simultaneously breeding the replacement tritium fuel.

— Science Of Nuclear Fusion: Insights and Ideas  (2609.01366 - Rafelski et al., 1 Sep 2026) in Section 1, subsection “Bottling weapon-grade fuel burn,” paragraph “Energy partition and tritium consumption”