  A design concept and characteristics for an epithermal breeder controlled by
variable feedback and external neutron source intensity are presented. By
replacing the control rods with neutron sources, we could improve safety and
perform radioactive waste burning in high flux subcritical reactors (HFSR). To
increase neutron source intensity the HFSR is divided into two zones: a booster
and a blanket operating with solid and liquid fuels. Use of a liquid actinide
fuel permits transport of the delayed-neutron emitters from the blanket to the
booster where they can provide additional neutrons or all the necessary
excitation. With blanket and booster multiplication factors of k=0.95 and 0.98,
respectively, an external photoneutron source rate of at least 10.sup.15 n/s
(electron beam power 2.5MW) is needed to control the HFSR that produces 300MWt.
An inexpensive method of obtaining large neutron fluxes is target-distributed
accelerators (TDA), in which a fission electrical cell (FEC) compensates for
lost beam energy in the thin photon production targets. The FEC is essentially
a high-voltage power source that directly converts the kinetic energy of the
fission fragments into electrical potential of about 2 MV.
