Q. To meet its rapidly growing energy demand, some opine that India should pursue research and development on thorium as the future fuel of nuclear energy. In this context, what advantage does thorium hold over uranium?

1. Thorium is far more abundant in nature than uranium.
2. On the basis of per ton mass of mined mineral, thorium can generate more energy compared to natural uranium.
3. Thorium produces less harmful waste compared to uranium.

Which of the statements given above is/are correct? (UPSC Prelims 2012)
Answer: 1, 2 and 3
Notes: The correct answer is [D] 1, 2 and 3. Thorium is considered the "holy grail" of India's three-stage nuclear power program, primarily because India possesses some of the world's largest reserves of thorium (found in monazite sands in coastal regions). Analysis of the Advantages:

• Abundance (Statement 1 is Correct): Thorium is estimated to be about three to four times more abundant in the Earth's crust than uranium. For India, this is a strategic necessity, as the country has limited high-grade uranium reserves but nearly 25% of the global thorium reserves.
• Energy Efficiency (Statement 2 is Correct): In a closed fuel cycle (using breeder reactors), thorium is highly efficient. Because nearly all of the mined thorium is the fertile isotope ²³²Th (which can be converted into fissile ²³³U), it can technically yield more energy per ton than natural uranium, which contains only about 0.7% of the fissile isotope ²³⁵U.
• Reduced Waste (Statement 3 is Correct): Thorium-based fuel cycles produce significantly less long-lived transuranic waste (like Plutonium, Americium, and Curium) compared to the Uranium-Plutonium cycle. The waste generated by thorium also drops to safe radiation levels much faster—in hundreds of years rather than the tens of thousands of years required for traditional nuclear waste.

Key Comparison Table

Feature	Uranium (235U / 238U)	Thorium (232Th)
Availability	Scarce (requires enrichment)	Abundant (Monazite sands)
Fissile Nature	Naturally fissile (235U)	Fertile (needs a "trigger" to become fissile)
Weaponization	Easy to divert for weapons	Difficult to weaponize (232U contamination)
Waste Profile	High transuranic waste	Lower long-term radiotoxicity