A transition to hydrogen alternative to fossil fuel awaits decades of technological and infrastructural developments. As a soft switchover from the present carbon based fuel resources, nuclear energy in electricity generation is being widely favored with no GHG emissions. Nuclear power comes from Uranium and Thorium, the latter being more abundant worldwide. This paper outlines the special features associated with a thorium burning molten salt (fluoride)/ breeder reactor (MSR/MSBR) to produce electricity.

On exposure to neutrons Th-232 transmutes to Th-233 which changes to Pa-233 in a few minutes. Pa-233 decays to U-233, a fissile isotope. Pa-233 has an undesirable affinity for capturing another neutron. Hence Pa-233 is isolated from neutron flux so that it decays as per planned to U-233, which is reintroduced in the neutron flux to undergo fission releasing atomic energy and additional neutrons to continue consumption of Th-232 in a cycle as before. The cycle of ‘expose-isolate-expose’ is accomplished satisfactorily in a MSR reactor. A solid core reactor is unsuitable. The lost neutron is sufficed by ‘priming’ to sustain a chain reaction.

In MSR/MSBR reactors, the coolant is air, not water. There is no danger of core meltdown. The U-233 fuel is gamma-emitter which is detected easily. The waste disposal problem is easily handled because the activity becomes nearly zero after 500 years of storage as against several thousand years from a U-235/Pu-239 reactors. Thus in one package a thorium burning reactor system addresses environmental, waste disposal, and security concerns. It is thus nuclear green with thorium.