The dual-use nature of nuclear energy, particularly fission, makes it an important component of both India’s vision for low-carbon future and secure through nuclear deterrence. In line with this India’s 3-stage nuclear programme is a strategy for a sustainable, continuous, reliable, and self-dependent supply of nuclear energy. India has about 25% of world’s thorium in the form of monazite sands (9%-thorium) along its coastline.
India’s three-stage nuclear power programme
Thus the 3-stage nuclear programme is developed with the aim of utilizing the vast thorium reserves as India has limited availability of Uranium reserves (about 2% of the world’s uranium reserves).
1st Phase – Natural Uranium-Based Reactor
U-235 being fissile sets up the chain reaction and U-238 being non-fissile gets converted to Pu-239 as a by-product (spent fuel). Essentially it is important for this ‘spent fuel’ which contains mixture of Pu-239 and U-238. The spent fuel is then chemically separated (reprocessed) for use in the second stage. The reactor type used is PHWR.
2nd Phase: Breeder-Reactors
Plutonium reprocessed in stage 1 is used as fuel in the core to produce energy. The extra neutrons produced in the core are used to produce more fuel. These extra neutron are allowed to be absorbed by either U-238 or Thorium-232 to produce more Plutonium-239 or Uranium-233 respectively. U-233 so produced is chemically separated (reprocessed) to act as fuel for the 3rd stage.
3rd Phase: U-233-Breeders
This is most important phase where U-233 obtained from the reprocessed spent fuel from 2nd stage acts as fuel in the reactor core to produce energy. The extra neutrons released are made to be absorbed by Thorium-232 outside the core to produce more U-233.
Smart Modular Reactors
- Also called nuclear battery or 4-S reactors (Super-safe Small and Simple)
- Reactors which produce 300 megawatts of electric power or les are called small modular reactors.
- These are 4th generation reactor design that are just collection of small modules.
- The only difference is because they are small they need very efficient coolant system for which liquid sodium is the idea choice.