Given its limited reserves of natural uranium and its
abundant supply of thorium, India has chalked out a
unique three-stage
nuclear program. In the first stage,
pressurized heavy water reactors (PHWRs)—similar to
those used in advanced industrial countries—burn
natural uranium. In the second stage, fast-breeder
reactors, which other countries have tried to
commercialize without success, will burn plutonium
derived from standard power reactors to stretch fuel
efficiency. In the key third stage, on which India's
long-term nuclear energy supply depends, power reactors
will run on thorium and uranium-233 (an isotope that
does not occur naturally).