Decarbonising Solution: Role of SMRs in energy transition

Being a low-carbon source of electricity, nuclear power plays a significant role in decarbonising the power sector. Small modular reactors (SMRs) present opportunities for the application of nuclear power in power generation. Given their modular nature, low cost and land requirements, SMRs are being considered for providing grid flexibility in addition to base load power.

A recent report by NITI Aayog on “The Role of SMRs in Energy Transition” highlights the role of SMRs in facilitating the energy transition. It also highlights the benefits and challenges associated with SMRs and outlines a potential roadmap for their deployment. Power Line presents the key takeaways from the report…

Key features and benefits of SMRs

As per the International Atomic Energy Agency (IAEA), SMRs are advanced nucl­e­ar reactors with a power generation capacity ranging from less than 30 MWe to 300+ MWe. These reactors are small in size compared to conventional nuclear power reactors. They feature modular sy­s­tems and components and are easy to install, transport and assemble. They utilise nuclear fission to generate heat for electricity production or direct application. Cogeneration SMR systems not only meet the electricity and process he­at requirements but also have the potential to complement variable renewables through flexible operations. Further, they can be installed in remote off-grid locations. Thus, they can play a crucial role in effectively achieving the energy transition goals.

SMRs offer several advantages. They are designed to have their systems, structures and components (SSCs) manufactured in a controlled factory environme­nt, and then transported to the project site for installation, which helps optimise project time and costs. They provide deployment advantages such as re­du­c­ed size of the emergency planning zone and use of passive safety systems. SMRs can also be considered for repurposing decommissioned fossil-fuel-fired power stations. SMR designs require refuelling every three to seven years, while some models can operate for up to 30 years without refuelling during their expected operating lifespan. They can increase the capacity of a power plant by adding more modules at a later stage. The capital investment per reactor is lo­wer, and the capital investment per MW, although higher compared to larger re­ac­tors (LRs), can be improved after the construction of more units.

Global status of SMR technology development and deployment

Governments, regulators, industry grou­ps, academic institutions and compani­es have taken various initiatives to dep­loy SMR technology. Several SMR desi­gns have obtained preliminary regulatory approvals, and are being considered for construction, operation and grid co­nnection. At present, two SMR projects have reached the operational stage globally. These include the Akademik Lomo­nosov floating power unit in the Russian Federation, consisting of two modules of the 35 MW(e) KLT-40S, which was grid-connected in December 2019; and the HTR-PM demonstration SMR in China, which achieved grid connection in December 2021 and is aiming for a full 210 MW(e) power operation in 2023.

Approximately 80 SMR designs are currently in various stages of development, licensing, deployment and operation on a global scale. Some of the popular SMR designs are:

  • Land-based water-cooled SMRs: SMRs in this category include water-co­oled SMR designs with different co­n­figurations of light water reactor and pressurised heavy water reactor (PHWR) technologies such as integral pressurised water reactors (PWRs) and PHWR, compact PWR, loop-type PWR, boiling water reactors and pool type PWR for on-land applications. These designs are built on mature technology used in most operational LRs.
  • Marine-based water-cooled SMRs: These SMRs include water-cooled SMR designs for deployment in mari­ne setups. They can be built on floating units installed on barges or ships.
  • High-temperature gas-cooled SMRs (HTGRs): HTGRs provide very high-temperature heat exceeding 750 deg­r­ees Celsius, resulting in increased efficiency in electricity generation. They are easy to integrate into various in­dus­trial applications and are well-suited for cogeneration.
  • Liquid metal-cooled fast neutron sp­e­ctrum SMRs: SMRs in this category include designs based on fast neutron technology with different coolant options including helium gas and liquid metal coolants like sodium, lead and lead-bismuth.
  • Molten salt reactor SMRs (MSRs): These SMRs use molten fluoride or ch­lo­ride salt as a coolant. MSR designs for both thermal neutron and fast neutron spectrums are under development. These technologies can sustain long fuel cycles that last several years and can be re-fuelled online whe­rein fresh fuel can be introduced in a molten form. The cleaning of fission products can be performed on­line with this method.
  • Microreactors (MRs): MRs are tiny SMRs designed to generate electrical power up to 10 MW(e). They use various coolants like light water, helium, molten salt and liquid metal.

Harmonising the licencing process and regulatory requirements

The NITI Aayog report notes that harmonisation of the licensing process and regulatory requirements will be a crucial step in expediting the development of SMR designs, reducing construction and in­stallation time, and optimising costs. Enabling policy and regulatory framewo­rks, along with legal aid and safety pr­o­visions, are essential for facilitating large-scale SMR manufacturing. The In­ter­national Atomic Energy Agency (IAEA) has played a pivotal role as an enabler in establishing these frameworks through initiatives such as the Nuclear Harmo­nization and Standardization Initiative, SMR Regulators’ Forum and the Coor­di­nated Research Projects.

Challenges in the industry

The report highlights various challenges faced by the SMR industry. It notes that the simultaneous development and adoption of a large number of SMR technologies would create regulatory challe­nges for the nuclear industry and reduce cost optimisation. In order to maintain economies of scale, it is imperative to na­rrow down the choices to a few SMR de­signs. Another challenge is the need for improvement of the Technology Rea­di­ness Levels of available SMR desi­gns, as this is essential for them to be considered for deployment by utilities, inves­tors and governments.  Apart from this, the report notes that the SMR in­dustry has yet to fully develop an operational fabrication facility for large-scale serial manufacturing of components. Estab­li­shing such a facility would requi­re a substantial inves­tment. This poses a challenge for technology developers who must secure fin­an­cing for te­chnology development, li­cen­sing and construction of prototype plants. In­suff­i­­ci­ent private capital further compounds this challenge.

The way forward for SMR deployment

The report notes that the focus on the SMRs is driven by the objective to create a standardised, small sized-reactor that can be manufactured repeatedly in a quality-controlled environment and in a standardised manner. Further, as the industry grows, the learning curve value and the economies of serial production can take effect and reduce the cost of production. Currently, the SMR industry is at a nascent but developing stage with ongoing technological evolution, prototyping of SMR modules, cost optimisation and regulatory clearances. The in­dustry must navigate through challen­ges related to technology demonstration, material availability, manufacturing techniques, project funding requirements and regulatory harmonisation.

The report notes that a sound SMR ecosystem depends on the standardisation of component designs and modules. The existing safety assessment methodology needs to be updated to account for the new technology of multi-module designs and the emergency planning zones of SMRs. It states that the availability of finance at lower rates of return, inclusion in green taxonomy and the utilisation of innovative financing instruments such as blended finance and green bonds can encourage private investment in the sector. Furthermore, the upskilling of personnel across the value chain, encompassing engineering, design, testing, inspection, construction, erection and commissioning for multi-module plants, is a necessity.

The report highlights that establishing strategic partnerships that foster collaboration among national laboratories and research institutions, academic institutions, private companies and government departments will result in optimal technological and economic outcomes. It also adds that these collaborative efforts should be extended at the IAEA level to coordinate with countries in developing an ecosystem that can yield greater benefits.


The SMRs are emerging as a reliable sol­ution for providing clean and reliable power supply, as well as for mitigating the intermittency issue of renewable en­ergy. However, it is crucial to address the challenges related to lack of a policy and regulatory roadmap, shortage of skilled manpower, harmonisation of standards and availability of financing, to ensure the successful development and deployment of SMRs.