Structure:
Introduction: (up to 30 words) Start by giving information about Thorium reserves in India and explain why Thorium cannot be directly used in Nuclear Reactors
Body: (up to 100 words) Explain India’s 3-stage Nuclear program to exploit Thorium in the future
Conclusion: (up to 30 words) Conclude by saying how Thorium may be the answer to meet India’s energy requirement.
Supporting Points:
Thorium is a naturally-occurring, slightly radioactive metal discovered in 1828 by the Swedish chemist Jons Jakob Berzelius. It is found in small amounts in most rocks and soils, where it is about three times more abundant than uranium.
Thorium is a basic element of nature, like Iron and Uranium. Like Uranium, its properties allow it to be used to fuel a nuclear chain reaction that can run a power plant and make electricity (among other things). However, Thorium itself will not split and release energy. Rather, when it is exposed to neutrons, it will undergo a series of nuclear reactions until it eventually emerges as an isotope of uranium called U-233, which will readily split and release energy next time it absorbs a neutron. Thorium is therefore called fertile, whereas U-233 is called fissile.
Since, Thorium is not Fissile, it cannot be directly used in a Nuclear Reactor
India’s three stage nuclear programme:
The long-term goal of India's nuclear program has been to develop an advanced heavy-water thorium cycle.
Stage 1- Pressurized Heavy Water Reactor (PHWR)
PHWRs are fuelled by natural uranium, and light water reactors, which produce plutonium incidentally to their prime purpose of electricity generation.
- Heavy water is used as moderator and coolant.
- U-238 → Plutonium-239 + Heat
Stage 2-Plutonium fuelled Fast Breeder Reactor
- It uses fast neutron reactors burning the plutonium-239 with the blanket around the core having uranium as well as thorium, so that further plutonium (ideally high-fissile Pu) is produced as well as U-233.
Stage 3- Advanced Heavy Water Reactors (AHWRs)
- It will burn thorium-plutonium fuels in such a manner that breeds U-233 which can eventually be used as a self-sustaining fissile driver for a fleet of breeding AHWRs.
- An alternative stage 3 is molten salt breeder reactors (MSBR), which are firming up as an option for eventual large-scale deployment.
India has modest uranium reserves, whereas it has one of the largest thorium reserves in the world. The country has long been eager to exploit its estimated 300,000 to 850,000 tonnes of thorium – hence, quite probably the world’s largest reserves found in the monazite sands of coastal regions of South India. Thorium, despite its greater abundance in nature and a number of superior characteristics, lags behind use of uranium as it does not have any fissile content. The fertile thorium-232 has to be converted into uranium-233 first for use in a nuclear reactor.
Considering the country’s vast thorium resources, the long-term nuclear energy policy of India has been focused on utilization of thorium early on. A three-stage nuclear power program was drafted already in the 1950’s.
The Indian nuclear establishment estimates that the country could produce 500 GWe for at least four centuries using just the country's economically extractable thorium reserves.
