Reply To: Competition from the Thorium reactor

[Brian H]

Axil wrote:

…

The dollar slope is just too steep, and expenses will aggressively seek the lower level.

This is an absolute truth. A low cost/price structure will always rule the day and overcome any resistance. Low cost Conquers All.

But this is only possible is the boron fusion fuel cycle is made to work in a highly productive manner and that is soooo hard to do. A D-D fusion backup plan is prudent to consider.

But the D-D option, as discussed above, carries a HUGE load of costs with it because it is lower yield and produces lotsa neutrons, some very energetic. AND it is a heat engine — back to the big boilers, nothankyewverymuch.

2H + 2H → 3H + 1H
………… → 3He + n
The optimum temperature for this reaction is 15 keV, only slightly higher than the optimum for the D-T reaction. The first branch does not produce neutrons, but it does produce tritium, so that a D-D reactor will not be completely tritium-free, even though it does not require an input of tritium or lithium. Most of the tritium produced will be burned before leaving the reactor, which reduces the tritium handling required, but also means that more neutrons are produced and that some of these are very energetic. The neutron from the second branch has an energy of only 2.45 MeV, whereas the neutron from the D-T reaction has an energy of 14.1 MeV, resulting in a wider range of isotope production and material damage. Assuming complete tritium burn-up, the reduction in the fraction of fusion energy carried by neutrons is only about 18%, so that the primary advantage of the D-D fuel cycle is that tritium breeding is not required. Other advantages are independence from limitations of lithium resources and a somewhat softer neutron spectrum. The price to pay compared to D-T is that the energy confinement (at a given pressure) must be 30 times better and the power produced (at a given pressure and volume) is 68 times less.

Wikipedia