Bob Higgins wrote:
What about the waste products from a hybrid fusion-fission reactor using natural U fuel? Would the neutron source drive the fission products to be either stable elements or to radioisotopes with shorter half life?
Not with small (desktop) accelerators as the basis of a makeup-neutron generator. That is asking too much. There needs to be a high multiplication ratio which limits the excess.
Basically, there are too few neutrons to spare and maintain instant shut-down capability. The idea is to have "just enough" flux, so that reactor goes into shut-down immediately on loss of accelerator power. No control rods. However, because a proper design would have a much reduced neutron flux to begin with (an order of magnitude less) the refueling time is greatly extended and may never be needed.
Thus, the inventory of U per watt is high, but comparatively - when you include enrichment losses necessary for the LWR the lifetime usage of U per watt is half as much with natural U, and without reprocessing - resulting in fuel cost which is one fourth - since operators pay a premium for enrichment.
What about using LENR as the neutron source? Some LENR fuels are reputed to cause "undesirable" neutron emission. Suppose that were harnessed.
Researching that possibility is one reason why I joined vortex back in the previous century but the question remains unanswered - unless you have an ace up your sleeve. What LENR fuels produce copious neutrons? Certainly a hybrid reactor with natural U would be a prime market. Remember that Miley, who used to know more about this than anyone, built his neutron generator around a Fusor... not exactly LENR.
