**8.6. External neutron sources for reproduction coefficient increase in thermal reactor**

External neutron sources can be included in neutron balance if it is linked somehow with reactor work. There are schemes, where neutrons, which are formed in reactions between accelerated protons and nuclei of heavy metals, are emitted to the reactor's core. This scheme has significant lack of reactor work reliability because of use less reliable source – electric nuclear installation. When autonomic electric nuclear installation is used only for 233U formation by neutron absorptions in thorium, reactor work almost is not depending on work reliability of electric nuclear installation. Work [21] demonstrates that raw uranium usage can be increased up to 100 % with use of comparatively small energy expenses (less than 2,5 % of produced energy).

Note, that modern thermal reactors, which use less than 1% or raw uranium, about 1% of produced energy spent for fuel enrichment.

Possible characteristics of joint work of fission reactor and neutron source based on fusion reactor are shown [22].
