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Comparison
D–³He vs p–¹¹B Fuel
Both are advanced low-neutron fuels. D–³He is the achievable commercial baseline; p–¹¹B is truly aneutronic but harder — the gated endpoint of the Kronos roadmap.
- Neutrons
- D–³He low-neutron (~5.25%); p–¹¹B aneutronic
- Difficulty
- p–¹¹B needs higher temperature still
- DEC optimum
- D–³He (³He-rich) η ≈ 0.60; p–¹¹B η ≈ 0.52
- Kronos role
- D–³He baseline → p–¹¹B gated endpoint
Both deuterium–helium-3 and proton–boron-11 are "advanced" fuels chosen to minimize neutrons — but they sit at different points on the difficulty/cleanliness curve, and Kronos treats them as sequential stages rather than alternatives.
| Property | D–³He / p–¹¹B |
|---|---|
| Neutron output | D–³He low-neutron (~5.25%, from side D–D); p–¹¹B truly aneutronic (no primary neutron) |
| Ignition difficulty | D–³He hard; p–¹¹B harder still (even higher temperature, more radiation) |
| Conversion optimum | D–³He peaks ³He-rich at η ≈ 0.60; p–¹¹B lower at η ≈ 0.52 |
| Kronos status | D–³He is the commercial baseline; p–¹¹B is a gated research endpoint |
Counterintuitively, the fully aneutronic p–¹¹B endpoint has a lower conversion optimum than the ³He-rich D–³He regime (analysis S71), which is why Kronos's economic operating point is ³He-rich D–³He, with p–¹¹B reserved as a destination on the staged fuel cycle.