Factors that augur well for small modular reactors


India’s geology poses a limitation on acquiring a large number of sites for setting up high capacity nuclear power plants (NPPs), which makes the case for installing small modular reactors (SMRs) in the country, notwithstanding the fact that Indian policymakers opted for large reactors in the initial phase of development to benefit from the economies of scale, according to a leading expert.

Speaking at a recent webinar organised by the New Delhi-based India Energy Forum, Sunil Ganju, who is Member of the Nuclear Controls and Planning Wing in India’s Department of Atomic Energy, said that the driving forces for introducing SMRs are the possibility of their “incremental deployment” in a context where “incremental demand can be closely matched with moderate financial commitment, especially for countries with smaller electricity grids”. The much lesser cost of setting up SMRs, as compared to large NPPs, provides a major rationale for opting for small modular reactors.

Elaborating on the current driving forces for SMRs, Ganju said these include their wider applicability in non-power applications like for district heating and industrial operations, besides the SMR’s higher safety quotient, as compared to large reactors, involving their passive and inherent safety features. “The lower core power density of SMRs and the large volume of water in the reactor power vessel delays all accident progression”, Ganju said.

Chancellor of the Homi Bhabha National Institute and former AEC Chairman, Srikumar Banerjee, said that there are currently two basic designs worldwide for SMRs, which are mostly of the Light Water Reactor (LWR) variety. These are the “Block”-type SMRs where the major components such as the steam generator, pressuriser and the water pumps are welded directly on to the reactor, and the “Integral’-type in which these components are all placed inside a single reactor pressure vessel (RPV) and weighs around 400-500 tonnes. According to Banerjee, the compact character of such small reactors allows mass production at a factory and easy transportation, instead of having to erect large reactors at a land site which involves much more civil engineering activity, a much longer gestation period, as well as huge costs and capital investment.

“The capital investment on every single SMR unit will be much cheaper than large capacity reactors. These SMRs can be set up at locations of thermal power plants being retired which take up a lot of space. SMRs can also come up in places which use off-grid power, especially in remote areas. Moreover, SMRs are useful in areas that depend on solar power, because they can provide the base load continuous power required on cloudy days” Banerjee said. In line with India’s target to reduce carbon emissions, it is estimated that most of its coal-fired thermal power plants would be retired by 2050.

Describing the origins of the small reactor nomenclature, Ganju said that while those of up to 300 MW capacity were referred to as “small”, others of up to 700 MW were called “medium”-type, and both categories together were known as Small and Medium Power Reactors (SMPRs). Noting the limitations of the current commercially proven nuclear technology such as the need to acquire large land sites, large project costs and delays, and safety issues, Ganju said that SMRs in the Indian scenario “are driven by and definitely congruent with India’s 3-stage nuclear programme, while SMRs of molten salt categories can use our vast thorium resources. The 500 MW Prototype Fast Breeder Reactor (PFBR – being developed at Kalpakkam in Tamil Nadu) can also be classified as a small reactor.”

At the Madras Atomic Power Station (MAPS) at Kalpakkam (Tamil Nadu), where work started in the early seventies and the first unit went on stream in 1983, everything has been built by India. The MAPS is India’s first fully indigenously constructed nuclear power station, with two units each generating 220 MW of electricity. The complex also houses the indigenously built prototype FBR – Bhavini – under construction, which will add 500 MW of electrical power to the national grid, and is likely to be operationalised in October 2022. By the early 1980s, India was able to design and build its own reactors and had achieved a high degree of self-reliance. The country subsequently designed and built pressurised heavy water reactors (PHWRs) at other locations, scaling up from 230 MW to 500 MW, and now up to 700 MW, the first one of which has been made functional in Kakrapar Unit 3. In July 2020, India achieved criticality with its first indigenously built 700 MW PHWR for the Kakrapar unit 3 in Gujarat state.

Russian state atomic energy corporation Rosatom arm Rusatom Overseas’ SMR Project Division Head, Svyatoslav Pikh said that Russia has a depth of experience in SMR projects since Soviet times, especially in its Far East and Polar regions, and is currently elaborating new SMR designs. “The world’s first Floating Nuclear Power Plant (FNPP), Akademik Lomonosov, is powered by an SMR and a site has been approved for setting up Russia’s first land based small reactor”, Pikh said.

The latest Russian SMR design – the RITM-200 – is the result of 400 reactor-years’ worth of combined experience operating small reactors on ships in country’s fleet of nuclear-powered icebreakers. Rosatom has already manufactured six reactors of the RITM series and installed these on three new icebreakers, while a total of 20 reactors have been fabricated for powering such icebreakers, according to Pikh.

The RITM-200 is an integrated generation III+ pressurised water reactor (PWR) designed to produce 55 MW electricity. The design is an improvement on the previous generation KLT-40S reactor that powers the FNPP Akademik Lomonosov, which can supply electricity to a town of more than 50,000 people and has already supplied to the Arctic city of Pevek, Pikh said. “The RITM series SMRs incorporate all the best features of the time proven PWR technology. It measures 45 percent less in dimension and 35 percent less in mass compared to the KLT-40S reactor”, he added. The RITM-200 has a compact integrated layout placing equipment within the steam generator casing, halving system weight compared to earlier designs and an improved ability to operate in rolling seas.

Pikh also elaborated on Rosatom’s land-based pilot SMR project involving the RITM 200, the design for which is in progress. In November 2020, Rosatom announced plans to place a land-based RITM-200 SMR in the isolated Ust-Kuyga town in Yakutia. The reactor will replace current coal and oil based electricity and heat generation at half the price. According to Rosatom, the construction of the SMR power plant will nearly halve the costs of electric power compared to the current prices in Ust-Yansky district in Far Eastern Russia. “The SMR project based on RITM-200 reactors features compact design, modularity, short construction period and high safety standards with the service life exceeding 60 years. The SMR construction in Yakutia will be completed by 2028”, a Rosatom statement said.

Describing the factors behind the success of SMRs, French state-run nuclear operator EDF’s Head of Technologies and Strategy, Sandro Baldi, said these include their modular design that helps to lower both cost and gestation periods, thereby, easing financing as well as international market access, and their “standardisation and series effect.” “The simplication will offset the scale effect of moving from large to a series of small reactors”, Baldi said, making a presentation of its “Nuward” small modular reactor that was unveiled at the International Atomic Energy Agency’s (IAEA) general conference in 2019 by EDF and its project partners – the French Alternative Energies and Atomic Energy Commission (CEA), Naval Group and TechnicAtome.

The Nuward – with a capacity of 300-400 MW – has been jointly developed using France’s experience in PWRs. The partners aim to complete the basic design of the Nuward between 2022 and 2025, while construction of a demonstration Nuward SMR is scheduled for 2030. According to Baldi, EDF have already started discussions with US major Westinghouse to explore potential cooperation on SMR development.