Small Modular Reactors: Explained, pointwise

Introduction

The Paris Agreement goals and SDG 7 has prompted an overhaul in worldwide energy supply technologies. With the advent of clean energy transition, there has been a great thrust towards adopting cleaner energy options to move towards the net zero emissions scenario by the respective countries. Apart from Renewable Energy, nuclear is also being explored as a clean energy option. Conventional Nuclear Powerplants have generally suffered from time and cost overruns. As an alternative, several countries are developing small modular reactors (SMRs) to complement conventional Nuclear Powerplants. India is also taking steps for development of SMRs to fulfill its commitment to Clean Energy transition.

Note: A clean energy transition refers to the process of shifting from conventional, fossil fuel-based energy sources to cleaner and more sustainable alternatives.

Why nuclear power is needed to supplement renewable energy?

The transition from coal-fired power generation to clean energy poses major challenges. Solar and wind energy alone will not suffice to provide affordable energy for everyone.

In decarbonised electricity systems with a significant share of renewable energy, the addition of at least one firm power-generating technology can improve grid reliability and reduce costs.

The grid integration costs of nuclear powerplants are lower than those associated with variable renewable energy (VRE) sources like solar and wind, because NPPs generate power 24×7 in all kinds of weather.

What are Small Modular Reactors?

As per the International Atomic Energy Agency (IAEA), the SMRs are advanced nuclear reactors with a power generation capacity ranging from less than 30 MWe to 300 MWe. SMRs are:

Small – physically a fraction of the size of a conventional nuclear power reactor.

Modular – making it possible for systems and components to be factory-assembled and transported as a unit to a location for installation.

Reactors – harnessing nuclear fission to generate heat for electricity production or direct application.

At present, nearly 80 SMR designs are under development and licensing stages, and a few of them are at deployment and operational stages globally.

Broadly, SMRs are classified as:

1. Land based water cooled SMRs: SMRs in this category include the water cooled SMR designs having different configurations of Light Water Reactor (LWR) and Pressurized Heavy Water Reactor (PHWR) technologies for on-land applications.
2. Marine based water cooled SMRs: SMRs in this category include the water-cooled SMR designs for deployment in a marine environment.
3. High-temperature gas-cooled SMRs (HTGRs): SMRs from this category can provide very high temperature heat of more than 750 degrees Celsius and thereby higher efficiency in electricity generation.
4. Liquid metal-cooled fast neutron spectrum SMRs (LMFRs): 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.
5. Molten salt reactor SMRs (MSRs): SMRs in this category are based on molten fluoride or chloride salt in the role of coolant.
6. Microreactors (MRs): MRs are very small SMRs designed to generate electrical power typically up to 10 MW(e). Different types of coolant, including light water, helium, molten salt and liquid metal are adopted by microreactors.

Both public and private entities are actively engaged to realize Small Modular Reactor (SMR) technology’s implementation before the end of this decade. As of now, two SMR projects have reached at operational stage globally: (i) The SMR named Akademik Lomonosov floating power unit in the Russian Federation (ii) The SMR named as HTR-PM demonstration SMR in China.

How Small Modular reactors are different from conventional nuclear powerplants?

SMRs are designed with a smaller core damage frequency (the likelihood that an accident will damage the nuclear fuel) and source term (a measure of radioactive contamination) compared to conventional NPPs.

SMR designs are also simpler than those of conventional NPPs and include several passive safety features, resulting in a lower potential for the uncontrolled release of radioactive materials into the environment.

The amount of spent nuclear fuel stored in an SMR project will also be lower than that in a conventional nuclear power plant.

What are the benefits of Small Modular Reactors?

SMRs are adaptable and scalable: SMRs are adaptable and can be scaled up or down to supply more or less power. It can also be used to supplement existing power plants with zero-emission fuel or to help repurpose ageing thermal power stations.

Refueling interval: SMR-based power plants might only need to refuel every three to seven years, as opposed to every one to two years for traditional plants. Some SMRs have a 30-year without refueling operating life expectancy.

Compact design: Land requirements in the case of SMRs are less as compared to land requirements for large reactors and renewable energy sources. SMRs are anticipated to reutilize parts of ageing/decommissioned fossil fuel based power plants.

Safety features: Extensive use of passive safety features in SMR designs, which rely on the laws of physics to shut down and cool the reactor under abnormal circumstances, provide inherent safety. In most cases, these technologies don’t need a power supply and can handle accidents without the assistance of a person or a computer.

Economical: SMRs require a low capital outlay and/or a phased capital expenditure. They have the adaptability to allow co-generation, supply heat for desalination and manufacturing etc.

SMRs are flexible: SMRs can be integrated with Renewable Energy to fulfill the need for flexibility, producing energy services, and low-carbon co-products. These can include electricity, hydrogen, synthetic fuels, hot process gases or steam. When coupled with variable energy sources SMRs can mitigate fluctuations on a daily and seasonal basis.

What are the challenges associated with Small Modular Reactors?

Technology choice issue: A large number of SMR technology alternatives are evolving at present, which are too many for sustained growth of SMR industry. A large number of technologies, if adopted for deployment at the same time, could not only create regulatory challenges for the nuclear industry but also take away some degree of cost optimization. The choices must narrow down to a few SMR designs.

Finance: The SMR industry is yet to realize fully developed operational fabrication facility for large scale serial manufacturing of SMR components. Such facility may necessitate a very large investment. There are also challenges in mobilizing finance for technology development, licensing and construction of prototype plants.

Licensing challenges: Newly developed SMR technologies may find it difficult to accommodate in the existing licensing process. The lack of experience with innovative designs within the nuclear safety regulatory organisations presents a substantial problem in examining and approving the safety standards.

Radioactive waste: SMRs also produce radioactive waste from spent fuel and require spent fuel storage & disposal facilities. Apart from the technological and cost aspects of such a requirement, this requirement can also lead to socio-political resistance.

Safeguards challenges: There is also a need to have a robust safeguards approach in place for novel technology.

Public perception and engagement: Nuclear power has faced traditional opposition due to the potential consequences of a nuclear disaster. Creating awareness is a challenge.

What are the legal and regulatory changes required for Small Modular Reactors?

The Atomic Energy Act will need to be amended to allow the private sector to set up SMRs.

To ensure safety, security, and safeguards, control of nuclear fuel and radioactive waste must continue to lie with the Government.

The government will also have to enact a law to create an independent, empowered regulatory board with the expertise and capacity to oversee every stage of the nuclear power generation cycle.

The Department of Atomic Energy must improve the public perception of nuclear power in India by better disseminating comprehensive environmental and public health data of the civilian reactors.

What should be the way forward?

Standardization of designs of components and modules will facilitate adoption of SMRs at large scale.

The existing safety assessment methodology should be updated for the concept of multi-module designs and emergency planning zones of SMRs.

Availability of low-cost finance, inclusion in green taxonomy and utilization of innovative financing instruments such as blended finance, green bonds, etc. are required to catalyze private investment.

Availability must be ensured of required skilled personnel across the value chain (engineering, design, testing, inspection, construction, erection and commissioning) for multi-module plants.

Strategic partnerships will be the key to successful technology development and deployment of SMRs on a large scale. Collaboration among national laboratories & research institutions, academic institutions, private companies and government departments is necessary.

These collaborative efforts would be required to be extended at the International Atomic Energy Agency level to coordinate with respective countries for developing an ecosystem for greater benefits.

Conclusion

SMR may complement large-size reactors to increase the nuclear share in energy mix and achieve Net Zero Emissions goals. The government will have to play a major role in consensus building towards nuclear energy by engaging relevant stakeholders.

Sources: The Hindu, Niti Aayog, IAEA