Is Kronos fusion aneutronic?

No. The D–³He burner is low-neutron, with a neutron fraction of about 5.44% — far below D–T's 79.7%, but not zero. Side D–D reactions produce neutrons, so 'aneutronic' would be an overstatement, and Kronos never uses the word for it.

The breeder is deliberately neutron-rich; its neutrons are the product. Only the far-future proton–boron endpoint approaches truly aneutronic operation, and Kronos frames that as a research destination, not its commercial baseline.