Question

Q83) Which of the following statements are true about Indian 3 stage Nuclear Programme?

1.The first two stages are natural uranium-fuelled heavy water reactors and plutonium-fuelled fast breeder reactors respectively.

2.Uranium is replaced by thorium as the fissile material in the third stage.

3. The shortage of thorium is hindering the deployment of the third stage.

• A. a) 1 and 2 only
• B. b) 1 only
• C. c) 2 and 3 only
• D. d) All of the above

Answer 1

The correct option is B

b) 1 only

Answer 83: B

Explanation: A fissile material is one that can sustain a chain reaction upon bombardment by neutrons. Thorium is by itself fertile,
meaning that it can transmute into a fissile radioisotope [U-233] but cannot itself keep a chain reaction going.
In a thorium reactor, a fissile material like uranium or plutonium is blanketed by thorium. India has very modest deposits of uranium
and some of the world’s largest sources of thorium. It was keeping this in mind that in 1954, Homi Bhabha envisioned India’s nuclear
power programme in three stages to suit the country’s resource profile. In the first stage, heavy water reactors fuelled by natural
uranium would produce plutonium [U-238 will be transmuted to Plutonium 239 in PHWR];
the second stage would initially be fuelled by a mix of the plutonium from the first stage and natural uranium. This uranium would
transmute into more plutonium and once sufficient stocks have been built up, thorium would be introduced into the fuel cycle to
convert it into uranium 233 for the third stage [thorium will be transmuted to U-233 with the help plutonium 239]. In the final stage, a
mix of thorium and uranium fuels the reactors. The thorium transmutes to U-233 which powers the reactor. Fresh thorium can replace
the depleted thorium [can be totally done away with uranium which is very scares in India] in the reactor core, making it essentially a
thorium-fuelled reactor [thorium keeps transmuting into U-233. It is U-233 that generates the energy].