Kakodkar Urges Thorium-HALEU Fuel in PHWRs as NPCIL Begins Fuel Loading at RAPP-8

The news

New Delhi and Rawatbhata, Rajasthan. Two developments reported by The Indian Express on 21 September sit side by side. First, the Nuclear Power Corporation of India Limited (NPCIL) began initial fuel loading at Unit 8 of the Rajasthan Atomic Power Project (RAPP) at Rawatbhata at 15:18 hours on 19 September 2026, after permission from the Atomic Energy Regulatory Board (AERB) following, in NPCIL’s words, “rigorous safety evaluations, major system integrity audits and site readiness reviews”. RAPP-8 is a 700 MWe indigenous pressurised heavy water reactor (PHWR) — a reactor that burns natural uranium and uses heavy water to slow neutrons — and the fourth of a series of 16 such units. Kakrapar Units 3 and 4 in Gujarat began commercial operation in 2023-24 and RAPP-7 in April 2025. The next step is the First Approach to Criticality, when a controlled chain reaction starts; fuel loading to commercial operation typically takes six to eight months, and NPCIL expects it this financial year. NPCIL has eight other reactors under construction — two each at Gorakhpur in Haryana and Kaiga in Karnataka, and four at Kudankulam in Tamil Nadu. Second, in an interview, Anil Kakodkar, former Chairman of the Atomic Energy Commission and now Chancellor of the Homi Bhabha National Institute, argued for introducing thorium into the PHWR fleet early, in parallel with Homi Bhabha’s three-stage programme conceived in the 1950s. His reasoning: global uranium resources can sustain only about 550-750 GWe in once-through mode over a 60-year reactor life, against about 1,400 GWe of capacity projected by the World Nuclear Association for 2050, so a uranium supply squeeze could hit India in 10-15 years. Fast breeder reactors are, in his estimate, two to three decades from fleet-mode deployment. Using HALEU-thorium fuel — thorium blended with high-assay low-enriched uranium — in PHWRs “without any significant design change” would, he said, open an earlier path to thorium irradiation at scale, cut spent-fuel inventory and save uranium, and could allow the third stage with thorium molten salt reactors to begin in about 15 years. He expects domestic PHWRs to take a major share of the 100 GWe nuclear mission up to 2047, with imported light water reactors making up most of the rest. Asked about the sector’s opening after the SHANTI Act, he stressed that fuel recycling must remain with the government.

Static syllabus linkage

1. The three-stage programme exists because India’s geology is lopsided. India has modest uranium reserves and one of the world’s largest thorium resources, found mainly in the monazite sands of the Kerala, Odisha, Tamil Nadu and Andhra Pradesh coasts. Thorium-232 is fertile, not fissile: it cannot sustain a chain reaction by itself and must first absorb a neutron to become uranium-233. Bhabha’s plan therefore has three stages — PHWRs burning natural uranium and producing plutonium, fast breeder reactors burning that plutonium and breeding more fuel, and finally reactors running on the thorium-uranium-233 cycle. The Prototype Fast Breeder Reactor at Kalpakkam, built by BHAVINI, is the flagship of the second stage.
2. A PHWR is India’s own reactor, not an imported design. A pressurised heavy water reactor uses natural uranium as fuel and heavy water (deuterium oxide) as both moderator and coolant, which is why it needs no enrichment plant. India began with the Canadian CANDU design at Rawatbhata and developed indigenous 220 MWe, 540 MWe and now 700 MWe versions. In 2017 the Union Cabinet approved ten 700 MWe PHWRs to be built in fleet mode — standardised design, bulk procurement and parallel construction — to cut cost and time. Light water reactors, by contrast, need enriched uranium and are the type India builds with foreign partners, as at Kudankulam with Russia.
3. HALEU sits between reactor fuel and weapons material. Ordinary power-reactor fuel is enriched to under 5% uranium-235, while high-assay low-enriched uranium is enriched to between 5% and 20%. Above 20% uranium is classed as highly enriched. HALEU’s higher fissile content lets it act as the ‘driver’ that supplies neutrons to thorium in a mixed fuel, which is the role plutonium plays in the original three-stage design. Because enrichment capacity is concentrated in a few countries, HALEU availability is itself a supply-security question.
4. AERB is the regulator, NPCIL the operator — and the separation is statutory. The Atomic Energy Regulatory Board was constituted in 1983 under the Atomic Energy Act, 1962 to carry out regulatory and safety functions, and its consent is required at each stage — siting, construction, commissioning, fuel loading and criticality. NPCIL, a public sector enterprise under the Department of Atomic Energy set up in 1987, designs, builds and operates the reactors. The Department of Atomic Energy reports directly to the Prime Minister, and the Atomic Energy Commission, set up in 1948, frames policy.

Why UPSC loves this

1. Nuclear energy is asked as energy security, not as physics. The GS3 syllabus lists ‘infrastructure: energy’ and ‘indigenisation of technology and developing new technology’. UPSC Mains has asked about the relevance of nuclear energy in India’s energy mix given its costs and fuel constraints, and the three-stage programme with thorium is the standard spine of such answers. Kakodkar’s proposal gives a current, named expert argument that modifies that spine.
2. Prelims tests the stages, the moderator and the regulator. Prelims questions on nuclear power have turned on which element is fertile and which fissile, what moderator a reactor uses, which reactor belongs to which stage, and which body regulates safety. The 2026 news adds HALEU and molten salt reactors as terms the examiner can now reasonably use in a statement.
3. The 100 GWe target makes every capacity addition examinable. Once a numerical national target is set, the examiner asks whether it is achievable. RAPP-8, the 16-unit PHWR series and the eight reactors under construction are the building blocks against which the target can be judged, and a candidate who can name them writes a better answer than one who repeats the target.

Analysis

1. Kakodkar is conceding, politely, that stage two has become the bottleneck. The original design assumed that fast breeders would multiply plutonium fast enough to seed a large thorium stage. His estimate that fleet-mode fast reactors are two to three decades away, and that they must first pass through oxide-fuelled, metallic-fuelled and new fuel-cycle transitions, amounts to saying the second stage cannot carry the timetable alone. Proposing a HALEU-thorium route in existing PHWRs is a way of running the third stage’s fuel physics without waiting for the second stage’s hardware. It is not an abandonment of Bhabha’s plan, but it is a significant change in its sequencing, and it comes from its most senior custodian.
2. The proposal swaps one dependency for another. Thorium in a PHWR needs a fissile driver, and in this scheme the driver is HALEU. India’s enrichment capacity is limited and the global supply of HALEU is concentrated. So the route reduces dependence on natural uranium imports while creating a need for enriched uranium, either produced at home at scale or bought abroad. Whether it improves self-reliance depends entirely on which of the two India can secure more reliably, and the interview does not settle that. An honest answer presents it as a trade-off, not a free gain.
3. Fleet mode is the real achievement and it is still slow. RAPP-8 is only the fourth of 16 700 MWe units, several years after the first two at Kakrapar reached commercial operation in 2023-24. Standardisation clearly works — each unit is described as strengthening the design — but the pace of one unit every year or two will not add up to the major share of 100 GWe by 2047 that Kakodkar expects. The bottlenecks are site acquisition, heavy components and construction management rather than reactor physics, which is why the opening of the sector matters: it is a bet that capital and project capacity, not technology, are the binding constraints.
4. Keeping recycling with the government is a non-negotiable, and it shapes the market. Kakodkar’s insistence that fuel recycling must remain within government reflects both non-proliferation obligations and the logic of the three-stage plan, where reprocessed fuel is the bridge between stages. The consequence is that any private or foreign participant will operate reactors inside a fuel cycle it does not control. That is a sound safeguard, but it means investors carry fuel-supply risk they cannot manage themselves, and the government’s reliability as fuel supplier becomes part of the investment case.
5. The counter-view: the uranium squeeze may be overstated. Projections of a uranium shortfall have been made before and have repeatedly been softened by new discoveries, higher prices bringing marginal mines into production, and slower-than-projected reactor building worldwide. If the World Nuclear Association’s 1,400 GWe figure is not reached, the pressure Kakodkar describes eases. The stronger version of his argument therefore does not rest on scarcity alone but on the spent-fuel and safety advantages he also lists, which hold whether or not uranium becomes scarce.

Administrator's brainstorm