UPSC Essentials brings to you its initiative for the practice of Mains answer writing. It covers essential topics from both the static and dynamic portions of the UPSC Civil Services syllabus across various GS papers. The questions are carefully selected on the basis of their relevance to the UPSC examination and current developments, helping aspirants focus on themes that matter most for Mains. This answer-writing practice is designed as a value addition to your UPSC CSE Mains preparation. Attempt today’s GS-3 questions and check your progress. Click Here to read the UPSC Essentials magazine for July 2026. Share your views and suggestions in the comment box or at manas.srivastava@indianexpress.comQUESTION 1India’s pursuit of 100 GW of nuclear power by 2047 marks a significant shift in its energy strategy. Discuss how nuclear energy, including Small Modular Reactors (SMRs), can contribute to India’s energy security and the growing electricity demands of emerging technologies. Also examine the challenges involved in scaling up nuclear power in India. QUESTION 2Indian Railways is moving closer to its goal of becoming a net-zero carbon emitter. Discuss the measures being undertaken by Indian Railways to achieve this objective and examine the challenges in its transition towards cleaner energy.QUESTION 1India’s pursuit of 100 GW of nuclear power by 2047 marks a significant shift in its energy strategy. Discuss how nuclear energy, including Small Modular Reactors (SMRs), can contribute to India’s energy security and the growing electricity demands of emerging technologies. Also examine the challenges involved in scaling up nuclear power in India.Relevance:The question is relevant to GS Paper III (Science & Technology, Energy and Environment). It connects current developments in India’s nuclear energy sector with core themes such as energy security, clean energy transition, indigenous technology, SMRs, nuclear fuel self-reliance and the growing energy requirements of emerging technologies such as AI, semiconductors and data centres. It also allows aspirants to link the three-stage nuclear programme, fast breeder technology and India’s thorium resources with contemporary policy initiatives.Note: This is not a model UPSC answer. It only provides you with a thought process which you may incorporate into the answers.Introduction:Story continues below this ad— Prime Minister Narendra Modi has set a target of expanding India’s nuclear power capacity to 100 GW by 2047 and commissioning five new nuclear reactors in this decade, as the country faces rapidly rising electricity demand from emerging sectors such as semiconductors, artificial intelligence (AI) and data centres. In his Independence Day address, Modi said the growing adoption of future technologies would drive a sharp increase in electricity demand. “It will be difficult to run this new world without energy, and therefore, whether it is chips, AI or data centres, we will need very large amounts of electricity,” he said. “We are working towards a target of 100 GW of nuclear power by 2047. In this decade itself, we have set a target of commissioning five new nuclear reactors,” he added. (File)Body:You may incorporate some of the following points in your answer:Why nuclear power is important— Growing adoption of future technologies will drive a sharp increase in electricity demand.Story continues below this ad— Nuclear energy offers baseload power and can give grid operators flexibility, particularly with the large-scale integration of renewables.— It offers a more carbon-neutral baseload generation option compared with thermal generation.— Nuclear energy can also contribute to industrial decarbonisation.India’s nuclear expansion strategy— India is pursuing a two-pronged approach: large-capacity reactors and Small Modular Reactors (SMRs).— Indigenous PHWRs will continue to form the backbone of nuclear expansion.Story continues below this ad— India is developing three types of indigenous SMRs: BSMR-200, 55 MWe SMR and a 5 MWt high-temperature gas-cooled reactor.— The government aims to have at least five indigenously designed and operational SMRs by 2033.— The Nuclear Energy Mission has a budgetary outlay of Rs 20,000 crore.Present status and long-term strategy— India currently has 25 operational nuclear reactors totalling 8.7 GWe, with 10 reactors under construction and another 10 in the pre-project stage.— India has developed and mastered indigenous PHWR technology.Story continues below this ad— The three-stage nuclear power programme aims at long-term fuel self-reliance.— The first stage uses natural uranium-based PHWRs, the second involves fast breeder reactors, and the third aims to use U-233 derived from thorium.— The first indigenous fast breeder reactor at Kalpakkam attained criticality, marking a major milestone.Challenges— High project costs of large light water reactors (LWRs) raise questions about their large-scale deployment.Story continues below this ad— India is seeking foreign expertise and investment for developing a domestic SMR ecosystem.— Wider private participation requires an appropriate framework for licensing, safety oversight and nuclear liability.— Scaling up nuclear capacity while integrating large-scale renewables requires careful attention to grid balancing and deployment choices.Conclusion:— India’s nuclear expansion combines large reactors, SMRs, indigenous PHWR technology and the three-stage nuclear programme.Story continues below this ad— The focus on fuel self-reliance, indigenous technology and newer reactor technologies can support India’s long-term energy requirements while complementing the expansion of renewable energy.(Sources: PM Modi’s 100 GW nuclear target: Why India needs more power for AI, chips and data centres)Points to Ponder— Can nuclear power provide the reliable, low-carbon electricity needed to complement renewables and meet the rising energy demand of AI, semiconductors and data centres?— Can India achieve 100 GW by 2047 while addressing the high costs of large reactors, safety and liability concerns, and the need for indigenous technology and fuel self-reliance?Related Previous Year QuestionsStory continues below this adWith growing energy needs should India keep on expanding its nuclear energy programme? Discuss the facts and fears associated with nuclear energy. (2018)QUESTION 2Indian Railways is moving closer to its goal of becoming a net-zero carbon emitter. Discuss the measures being undertaken by Indian Railways to achieve this objective and examine the challenges in its transition towards cleaner energy.Relevance: This question is relevant to GS Paper III (Environment, Energy and Infrastructure). It connects Indian Railways’ net-zero target with themes such as decarbonisation of transport, railway electrification, renewable energy, energy efficiency and India’s broader climate commitments. It also tests the ability to link a current infrastructure development with the environment and energy sections of the UPSC syllabus.Note: This is not a model UPSC answer. It only provides you with a thought process which you may incorporate into the answers.Introduction:— Indian Railways is moving closer to becoming a net-zero carbon emitter, with its decarbonisation efforts having wider significance for India’s climate goals. The decarbonisation of railways will have a notable impact on India’s climate commitments, energy security, as well as the broader development trajectory.Body:You may incorporate some of the following points in your answer:Measures towards net-zero— Electrification of railway routes as a key component of reducing dependence on diesel.— Increasing use of renewable energy in railway operations.— Measures to improve energy efficiency across the railway network.— Greater use of solar power as part of the Railways’ clean-energy transition.2. Significance— Indian Railways accounts for roughly 2% of the national grid’s output, making its decarbonisation push consequential for India’s climate goals.— The transition can help reduce the carbon footprint of one of the country’s largest transport networks.— The move towards renewable energy can reduce dependence on conventional sources of electricity.3. Challenges— The large scale of the railway network makes the transition towards net-zero a complex and long-term process.— Increasing the share of renewable energy while meeting the Railways’ substantial electricity requirements remains an important challenge.— The transition requires continued progress in electrification, renewable energy adoption and energy efficiency.Conclusion:— Indian Railways’ movement towards net-zero emissions reflects the broader shift towards cleaner and more sustainable transport.— Continued electrification, renewable energy adoption and energy-efficiency measures will be central to sustaining this transition.(Source: How the Indian Railways moves closer to becoming net-zero carbon emitter by 2030)Points to Ponder— Indian Railways’ decarbonisation is significant not only for the transport sector but also for India’s broader climate goals. Discuss.— How can electrification, renewable energy and energy efficiency together accelerate Indian Railways’ transition towards net-zero emissions?Related Previous Year QuestionWhy is Public Private Partnership (PPP) required in infrastructural projects? Examine the role of PPP model in the redevelopment of Railway Stations in India. (2022)Previous Mains Answer PracticeUPSC Essentials: Mains answer practice — GS 3 (Week 166)UPSC Essentials: Mains answer practice — GS 3 (Week 167)UPSC Essentials: Mains answer practice — GS 2 (Week 166)UPSC Essentials: Mains answer practice — GS 2 (Week 167)UPSC Essentials: Mains answer practice — GS 1 (Week 165)UPSC Essentials: Mains answer practice — GS 1 (Week 166)Subscribe to our UPSC newsletter and stay updated with the news cues from the past week.Stay updated with the latest UPSC articles by joining our Telegram channel – IndianExpress UPSC Hub, and follow us on Instagram and X.