While SMRs (small modular reactors) are a natural choice for localised grid applications, smaller reactors would mean larger number of reactor units, leading to bigger risk of a major accident, unless their safety is at a correspondingly higher level. Not all SMRs would meet this criteria, according to the country’s top nuclear scientist ANIL KAKODKAR.Now that India is able to build large PHWR (pressurised heavy water reactor) capacity with imported uranium (as fuel), the country has the possibility of using this reactor capacity for conversion of thorium to fissile uranium through irradiation of thorium along with HALEU (a fuel variant called high assay, low enriched uranium) in the country’s PHWRs at scale. This enables the launch of the thorium phase (the third phase of India’s three-stage nuclear programme) earlier, without having to wait for build up of required fast breeder reactor capacity.Also read | Putin’s N-power hard sell: SMRs, new-gen large nuke reactors, serial production in IndiaThe used fuel from these PHWRs – the mainstay of India’s nuclear power programme – can then be recycled to set up additional power generation capacity, including through the new-age molten salt reactors or MSRs as part of the third stage of India’s three-stage nuclear power development programme. This will enable faster energy independence from imported nuclear fuel, Kakodkar, who is now the Chancellor of the Homi Bhabha National Institute and the Chairman of the Rajiv Gandhi Science & Technology Commission, and was former Chairman, Atomic Energy Commission, told The Indian Express. Edited excerpts:Q. The new overarching atomic power legislation — SHANTI Act 2025 — among other things, does away with the key provisions of right of recourse in the Civil Liability for Nuclear Damage Act, 2010 and opens the door for private operators and possible foreign participation. What are your views on these specific provisions of the new legislation?A. The provisions for right of recourse were modified during parliamentary discussion on the earlier Civil Nuclear Damage Act, 2010, perhaps driven by the Union Carbide experience. This meant large residual liability that would remain on the books of suppliers. This led to blocking of further nuclear build activity. While solutions could be found in case of domestic technology and extension of ongoing programmes, entry of new suppliers remained a challenge. Hopefully this would get resolved with right of recourse provisions getting aligned back to global practice in the new act.Aspect of who would eventually bear the responsibility for damage arising due to latent defects in design or equipment would be a question to be settled between operator and supplier with the operator holding that responsibility in any case.Q. The view in Delhi’s policy circles is that this move to look outwards (internationally) for nuclear has been triggered by two issues: a need for baseload power to rebalance the growing renewable portfolio in the grid and a requirement for capital for scaling up nuclear power. But it was also underlined that this pursuit is not driven by a need for technology. How viable is our own PHWR-based capacity addition programme, given the scalability has been cited as a constraint?A. Home grown PHWR technology, is fully mature and has competitive advantage in terms of economics, safety and uranium utilisation. Moreover, PHWRs are flexible in terms of fuel cycle and are an ideal platform for large scale conversion of thorium into fissile uranium and launch the thorium based power generation at scale. Scale up of PHWR capacity is a new opportunity for quicker transition to thorium based nuclear power generation in India.Also read | SHANTI Bill: How India is overhauling its nuclear power sectorScaling up PHWR capacity to the required level ( say around 50 to 80 GW) as well as mobilising the necessary financial resources, by the year 2047, requires bringing in a number of additional players. Constructive mentoring by NPCIL with enabling provisions of the new act would hopefully facilitate this process.Renewable energy sources as have evolved thus far, are primarily variable. Significant additional investments are needed to maintain the mandated stable frequency and voltage in the grid. Without the grid having a significantly large fraction of base-load sources, these investments become prohibitively large leading to high electricity tariff for end consumers. Nuclear power not only provides such baseload supply but also is the only clean energy source with large enough potential to support the needs of ‘Viksit Bharat’.Story continues below this adQ. Given that for imported Light Water Reactors, India will have to look externally for technology, does that present some challenges in the wake of someone like US President Donald Trump simply turning the tap off on either tech or fuel in the future?A. While PHWRs would necessarily constitute the mainstay of Nuclear Energy Mission, Well proven LWR technology could provide useful additionality. Hopefully, legal contracts once established would be respected. Even so, we must be prepared to deal with such challenges, should they arise. Given the present technological capability of the country and diversity of supply chain, we should be able to deal with such situations though with some cost and time penalties.The real answer to such vulnerabilities lies in becoming technology and energy independent through leveraging thorium at the earliest.Also read | India moves towards unlocking nuclear energy. The hard work begins nowQ. You’ve said earlier that the private sector, while it needs to be mobilised to scale up the programme, has, at best, “a secondary role”. And that nuclear power today is competitive without any subsidy, and so be given must-run status, and be backed up by a clean energy fund, just like for renewables. This new legislation essentially places primacy on fostering the private sector role in nuclear energy. How do you see this policy pivot?A. Nuclear power is indeed competitive without any subsidy. However, it is important that since nuclear energy brings in larger potential for clean energy supply, it should be treated on a level playing basis.Also, apart from significantly enlarging share of nuclear energy in the grid supply through large nuclear power plants, there are niche areas for small nuclear power plants such as, to meet captive clean energy requirements of industries as well as to leverage brown field opportunities at retiring coal plant sites. Private sector can effectively participate here.Story continues below this adQ. How do you see the viability of SMRs for localised applications, such as data centre operations, in India?A. SMRs are a natural choice for localised applications. However, their viability would be a question till their order books become large and value addition locally becomes near 100%. Further, smaller reactors would mean larger number of reactor units leading to larger risk of a major accident unless their safety is at a correspondingly higher level. Not all SMRs would meet this criteria. Deploying SMRs should be done keeping these aspects in mind.Q. Given the impediments being faced in the large-scale deployment of Fast Breeder Reactors, does a solution lie in looking at fuel cycle options instead of reactor options. Can the solution lie in irradiating thorium along with low enriched uranium in the PHWRs at scale? Can we skip the second stage entirely then?A. We need to be able to establish, as early as possible, self-sustaining (or near enough) thorium based nuclear power generation capacity sufficient enough to meet the needs of ‘Viksit Bharat’. This, in turn, requires reactor capacity large enough to convert required quantity of fissile uranium from thorium in time. Earlier this reactor capacity was envisaged to be built through breeding in fast reactors as uranium availability was limited. Now that we are able to build large PHWR capacity with imported uranium, we have the possibility of using this reactor capacity for conversion of thorium to fissile uranium through irradiation of thorium along with HALEU and launch the thorium phase earlier without having to wait for build up of required fast reactor capacity. This will enable faster energy independence from imported nuclear fuel.Fast reactor development would however remain important to produce fissile material through breeding if it becomes necessary to support further growth when uranium import faces challenges. An important factor for self reliance or energy independence.