Research Highlights

Fuel for thought

Biplab Das

doi:10.1038/nindia.2008.268 Published online 31 August 2008

Balanced use of nuclear fuels in thorium breeder reactors could enhance their efficacy dramatically, new research suggests1. The results of the research could help design nuclear reactors with faster fusion growth.

When a neutron hits a heavy atom (uranium-235), the latter splits into two atoms releasing energy in the process. Uranium-235 is said to be fissile (fissionable). But by hitting a uranium-238 atom, it is unlikely to cause splitting (fission). Instead, uranium-238 and neutron combine. So, uranium-238 is said to be fertile.

Though the mechanical and thermal properties and irradiation behaviour of thorium are better than that of uranium, economic viability and hazards of handling limit the use of thorium. To avert this, the researchers devised a novel concept.

Loading of seedless fertile rods (thorium) has been used as the central principle to maximize fertile to fissile conversion in the thorium breeder reactor. According to the concept, at fresh state the seedless thoria rods will produce practically no fission power, or nearly thousand times less fission rate compared to the seed fuel rods. The researchers say by judicious choice of the rod dimensions and their relative locations, a degree of balance in the fission rate is achieved in the fresh state of seeded rods.


  1. Pal, U. et al. Physics principles to achieve comparable fission power from fertile and fissile rods of the conceptual ATBR/FTBR reactors. Ann. Nucl. Energy. 35, 1636-1641 (2008) | Article |