One of the most important topics both from the point of view of prelims and mains.
India envisages A Three Stage Programme based on the optimum utilisation of the indigenous limited uranium and abundant thorium resources. It was formulated by Dr. Homi Bhabha in the 1950s to secure the country’s long term energy independence.
STAGE 1 » Pressurised Heavy Water Reactor
STAGE 2 » Fast Breeder Reactor
STAGE 3 » Breeder Reactor
Why the 3 stages?
Although we have around 25% of the world’s thorium reserves, it itself is not a fissile material. It needs to undergo transmutation to U-233 in a reactor fuelled by other fissile material.
The sequential 3-stage programme is based on a closed fuel cycle, where the spent fuel of one stage is reprocessed to produce fuel for the next stage.
The diagram below should explain that.
STAGE 1: PRESSURIZED HEAVY WATER REACTORS(PHWR)
- Natural Uranium is used as a fuel and heavy water as a coolant and moderator
- The 0.7% U-235 undergoes fission to release energy. As the remaining 99% U-238 is not fissionable, it undergoes transmutation and forms Plutonium-239(Pu-239).
Working of the reactor –
- The heat is removed from the reactor by water flowing in a closed pressurised loop
- The heat is transferred to a second water loop through a heat exchanger.
- The second loop is kept at a low pressure allowing the water to boil and create steam, that is used to turn the turbine-generator
- Then the steam is condensed into water and returned to the heat exchanger
VVER – Reactors
Two Russian-built VVER-1000 reactors have been in commercial operation in Kudankulam, southern India, since 2014 and 2017 respectively.
STAGE 2: FAST BREEDER REACTORS(FBR)
- The reactor is fuelled by a mixed oxide of U-238 and Pu-239 which have been recovered by reprocessing the spent fuel in the first stage
- Pu-239 undergoes fission producing energy and more Pu-239 through the transmutation of U-238.
Working of the reactor –
- Why fast? The neutrons are not slowed down. There is no need of a moderator
- Why breeder? More fissionable material(Plutonium) will be present after the reaction than what was present before the reaction. It breeds fissile material.
- In FBR, the fission chain reaction is sustained by fast moving neutrons.
- India and Russia are the only two countries that are constructing commercial scale breeder reactors.
- Solves 5 problems — safety, competitiveness, shortage of fuel, reprocessing and refabricating the used nuclear fuel and radioactive waste. Enforcing non-proliferation of fission materials and weapon technologies
The multipurpose fast reactor project, known by the Russian acronym MBIR, is coming up at the International Research Centre in Dimitrovgrad located in the Ulyanovsk region in Russia.
It is a fast reactor project follows the closed fuel cycle.
Transitioning to closed fuel cycle which is based on fast neutron reactors can solve five essential problems:
safety, competitiveness, shortage of fuel, reprocessing and refabricating the used nuclear fuel and radioactive waste.
It also addresses the non-proliferation of fission materials and weapon technologies.
The main purpose of the MBIR is to conduct large no. of reactor studies of Generation-4 nuclear systems.
MBIR’s design includes three independent loops that can be used to test different coolants like gas, lead, molten salt and others.
STAGE 3: THORIUM BASED REACTORS
- It is based on the Thorium Uranium-233 Cycle.
- Naturally occurring Thorium-232 is not a fissile material. It needs to be converted to a fissile material, U-233, by transmutation in a FBR
- In the second stage, once sufficient Pu-239 is built up, Thorium-232 is introduced as a blanket material to be converted to Uranium-233.
KAMINI (Kalpakkam Mini reactor) in Kalpakkam is the world’s only thorium-based experimental reactor. It achieved criticality on 1996. Designed and built jointly by the Bhabha Atomic Research Centre (BARC) and Indira Gandhi Centre for Atomic Research (IGCAR), it produces 30 KW of thermal energy at full power.
Sites with Nuclear Power Plants
- As of 2017, India has 22 nuclear reactors in operation in 7 nuclear power plants with an installed capacity of 6780 MWe.
- With a total capacity of 1400 MWe, Tarapur is the largest nuclear power station in India
- Kundankulam Nuclear Power Station started its commercial operation in March 2017
Department of Atomic Energy(DAE)
- It is under the direct charge of the Prime Minister.
- Engaged in the development of nuclear power technology and applications of radiation technology.
Atomic Energy Commission(AEC)
- It is the governing body of the DAE.
- It organises and promotes atomic research and train atomic researcher in the country.
- It is the main policy making body.
International Thermonuclear Experimental Reactor(ITER)
- It is an international nuclear fusion research and engineering mega project which will be the world’s largest magnetic confinement plasma physics experiment
- What is Plasma Physics? It is the study of charged particles and fluids with interacting with self-consistent electric and magnetic fields
- It is being built next to the Cadarache facility in Southern France
- India is a part of ITER.
International Atomic Energy Agency(IAEA)
- It seeks to promote the peaceful use of nuclear energy and inhibit its use for any nuclear purpose, including nuclear weapons.
- HQ located in Vienna, Austria.
- India is a member of the IAEA.
Convention on Supplementary Compensation(CSC)
- It seeks to establish a uniform global regime for compensation to victims in the unlikely event of a nuclear accident.
- India has ratified the convention.