# The Azimuth Project Thorium

Thorium (Th) is a transition element in IVB group of the periodic table with atomic number 90. The natural isotope is thorium 232 with half-life of $1.4 \times 10^10$ years (14 milliards, or 14 US billions) decaying via $\alpha$-decay; other isotopes (228, 230, 231, 234), are found only in traces and 229 only synthesized in the laboratory. Thorium 232 is more abundant (by factor of 4-5) in Earth’s crust than all the isotopes of uranium combined and it does not require isotopic separation; 25% of the world reserves are estimated in India.

## Thorium reactors

Thorium reactors are based on the fact that thorium 232 absorbs slow neutrons released by uranium 233. India plans to build a thorium-based Advanced Heavy Water Reactor and already uses thorium as a substitute for depleted uranium in Kakrapar-1 to achieve power flattening across the reactor core (Kakrapar_Atomic_Power_Station). There is an ongoing construction in Texas (wikipedia: HT3R).

Thorium reactors have better efficiency, consume some of the usual nuclear waste (cf. Nuclear power), and thorium is more abundant than the uranium 235; they operate at higher temperature (around 700 C) and have to be cooled by liquid lead rather than with water. Yacine Kadi, an applied physicist at CERN in Geneva is developing a new generation of thorium reactors which would consume much nuclear waste.