Nuclear Science and Technology

ITER, under construction at Cadarache in France, is a collaboration of the European Union, India, Japan, China, Russia, South Korea and the United States, building a tokamak intended to demonstrate that a burning deuterium-tritium plasma can produce ten times the power injected to heat it. Its purpose is to establish the scientific and engineering feasibility of fusion as an energy source, and India's participation, through the Institute for Plasma Research, brings both technology and eventual access to the design knowledge. If the experiment succeeds, what India gains is the capability to build fusion reactors, giving (d).

• Option (a) confuses fuel cycles: thorium belongs to fission, and India's thorium ambitions run through the three-stage programme and the Advanced Heavy Water Reactor, not through ITER.
• Option (b) is unrelated to nuclear physics of any kind.
• Option (c) commits the same category error in the opposite direction, since success in magnetic confinement fusion tells one nothing about the efficiency of fission reactors, the two processes being physically distinct. The elimination route is complete once the candidate holds fission and fusion apart, since three of the four options describe fission or non-nuclear outcomes.

• Option (a) is the answer the key takes and it is correct in substance. The entire logic of India's post 2005 nuclear arrangements is a separation of the civilian from the strategic programme: designated civilian facilities are offered for safeguards while the military programme stays outside, and it is this bifurcation that made international nuclear commerce possible for a State outside the Non Proliferation Treaty.
• Option (b) is wrong precisely because it inverts that bargain; no instrument brings India's military nuclear installations under IAEA inspection, and had any done so the arrangement would have been politically impossible.
• Option (c) is wrong because uranium purchase rests on the clean waiver granted by the Nuclear Suppliers Group in September 2008 and on the bilateral agreements concluded afterwards with the United States, France, Russia, Kazakhstan, Canada and Australia; safeguards are a precondition for those transactions rather than the source of the entitlement, and the Group is in any event a set of guidelines rather than a seller.
• Option (d) is wrong for the same reason as statement 2 of question 7 in this paper: no safeguards instrument confers membership of the Nuclear Suppliers Group, which is decided by consensus among its participating governments and has repeatedly been withheld from India.

Hence (a).

Under the separation plan that followed the India United States civil nuclear agreement of 2008, India divided its reactors into a civilian list and a strategic list. Reactors that use imported uranium, or that were built with foreign assistance, are placed on the civilian list and accept International Atomic Energy Agency safeguards, which verify that the fuel is not diverted to weapons use. Reactors running on domestically mined uranium remain outside safeguards, preserving freedom of action for the strategic programme. Hence (b).

• Option (a) is wrong because no Indian power reactor runs on thorium as primary fuel; thorium enters only in the third stage of the programme, and safeguards attach to fuel origin rather than fuel type.
• Option (c) is wrong because no reactor in India is operated by a foreign enterprise.
• Option (d) is wrong because there is no private ownership of reactors, operation resting with the Nuclear Power Corporation and Bhavini.

• Statement 1 is correct. Monazite is a phosphate of the light rare earth elements, chiefly cerium, lanthanum, neodymium and praseodymium, and it is the principal rare earth bearing mineral worked in India.
• Statement 2 is correct. Monazite characteristically carries thorium in the lattice, typically of the order of eight to ten per cent as thorium dioxide, which is why India's beach sands underpin the thorium based third stage of the nuclear programme.
• Statement 3 is incorrect, and the word entire is the giveaway. Monazite occurs in economically significant concentration only in particular placer deposits, principally along the Kerala and Tamil Nadu coasts and in parts of Odisha and Andhra Pradesh, where wave and current sorting has concentrated the heavy minerals. Long stretches of the Indian coast carry no such deposits.
• Statement 4 is correct. Monazite is a prescribed substance under the Atomic Energy Act on account of its thorium content, and its processing and export are reserved to government entities, in practice Indian Rare Earths Limited, while private operators may handle the other beach sand minerals.
• Statements 1, 2 and 4 hold, giving (b).
• Options (a), (c) and (d) each admit the overstated distribution claim in statement 3.

• Statement I is correct. Coal supplies roughly seventy per cent of India's electricity generation while nuclear power contributes around three per cent, notwithstanding domestic uranium in Jharkhand and Andhra Pradesh.
• Statement II is incorrect and is the crux of the question. Power reactors run on low enriched uranium of about three to five per cent uranium-235, and India's indigenous pressurised heavy water reactors use natural uranium at 0.7 per cent because heavy water moderation removes the need for enrichment altogether. Enrichment to sixty per cent and above belongs to the weapons and high performance research reactor domain, not electricity generation. Since Statement I is correct and Statement II is false, (c) follows.
• Options (a) and (b) require Statement II to be true, and (d) inverts the truth values.

• Statement 1 is incorrect. An RTG is not a reactor of any size. It contains no chain reaction, no criticality and no control mechanism. It converts the heat of spontaneous radioactive decay directly into electricity through thermocouples using the Seebeck effect.
• Statement 2 is correct. RTGs power onboard systems on missions where sunlight is too weak or intermittent for photovoltaics, as on Voyager, Cassini, New Horizons, Curiosity and Perseverance.
• Statement 3 is correct. Plutonium-238 is produced by neutron irradiation of neptunium-237, itself a by product of the reactor operations and reprocessing associated with weapons programmes, and its 87.7 year half life and alpha emission make it well suited to RTGs. Hence 2 and 3 only, which is (b).
• Options (a), (c) and (d) all retain the fission reactor error.