Planet earth is reeling under an unprecedented threat of our time, the climate crisis. Change in weather pattern – that affects farm produce and causes rise in sea level – and destruction of natural resources top the list of ten biggest problems in the world. Though the eight billion people on earth are divided by borders, culture, language, ethnicity and so on, humanity is getting united by emotions largely for climate crisis. While environmentalists and policy makers are busy in advocating life style changes (such as minimal usage of electricity, travelling by public transport, ways to reduce individual carbon footprint, etc.) to hold back temperature issues, the scientists and engineers across the globe are into technological innovations (such as carbon-free electricity generation, pollution-free transportation, green industries, etc.) to reverse the changing climate.
Towards that goal, world countries are vowing to cap the carbon dioxide emission, a gas which is responsible for earth’s temperature rise, and religiously focusing to reach net zero, a state when a balance between emission of greenhouse gases and removal of atmospheric pollution is attained. While many developed countries like USA, UK, Japan and Australia are targeting to achieve net zero by 2050 or before, China, the biggest emitter of CO2 in the world, is aiming it by 2060. India too has sworn to reach net zero by 2070.
Burning of fossil fuels for human needs such as electricity, heat and transport is regarded as one of the largest sources of carbon dioxide and other greenhouse gases. There are many other sectors like industries and agriculture that emit greenhouse gases, nevertheless, these three, according to the findings of the Intergovernmental Panel for Climate Change (IPCC), account nearly 40% of world emission.
The nuclear push
To begin with, if this 40% is kept in check, as climate scientists believe, global warming can be restrained. And for that very reason, a big push to nuclear power generation is being given worldwide. In its December 28, 2022 editorial titled “Net zero isn’t possible without nuclear,” The Washington Post reckons that the world can’t decarbonise without nuclear power. Nuclear power plants produce electricity by 24×7 with almost zero or insignificant emission. Worldwide there are 422 operating nuclear power reactors, which are capable of generating over 378 Giga Watts of electricity per hour. And presently nuclear contributes about 11% in world electricity generation. And 57 new nuclear power plants with an installed capacity of 58 GWe are being built.
Going compact
Given the ferocity of the prevailing situation, climate scientists and advocates of clean energy production across the world ponder that the current nuclear share is not just enough.
According to the International Energy Agency, nuclear output should at least be doubled by 2050 to bring the global emissions down. So, interest in small modular reactors is growing globally in a rapid manner. Worldwide, attempts are being made to develop small modular reactors of about 60 MWe to 300 MWe capacity. Although SMRs were thought of long ago, until Russia commissioned world’s first floating SMR (35MWe capacity), named as Akademik Lomonosov, in 2020 no small modular reactors have been built.
Why SMRs are better?
SMRs have a slew of advantages over the conventional nuclear power reactors. First, as the name suggests, they are physically small. Somewhat, the height of a normal nuclear power reactor ranges from 50 to 70 metre while its diameter is of 50 meter on an average. Comparatively, the small modular reactors are expected to be nearly half of this physical size or even less. Therefore, the conundrums being faced by nuclear engineers while dealing with over-dimensional buildings and components will diminish.
Until now, nuclear power reactors are built in-situ. Means, they are constructed in their original place – and nuclear components are placed in the building at their respective positions. But SMRs are going to change the way nuclear power plants are built. Like automobiles or computers, SMRs can be factory built. It is quite possible to fabricate the systems and components of these miniature reactors in a factory and to assemble the parts into a reactor. Such prefabricated units can be transported to any appropriate location and installed. There are two notable benefits here: One, small reactors can be built in bulks, leading to cost savings. Two, it saves time. The construction delays in conventional reactors that usually lead to cost overruns can very well be averted in SMRs owing to the simplicity in design.
As space requirement is comparatively very less, these plug-and-play units can be setup anywhere and connected to the grid. In its definition to SMR, the International Atomic Energy Agency (IAEA), states that they can be deployed as a single or multi units in a place. If demand arises in the future more SMRs can be added in the same space to increase the capacity, it adds. Besides, SMRs offer great flexibility: where large power plants are not needed (like isolated places, smaller grids, islands and hill stations) these are the best solution to provide power applications. And contrary to the large capacity nuclear reactors that are to be shutdown once in a year or two years for refuelling, SMRs can run continuously for two to three years. Another notable plus of SMRs is that they can go well with other power generation technologies. They can be deployed along with windmills or solar farms or even with thermal power plants.
Fortified safety
In his study report “An overview of the safety of case for small modular reactors”, Mr. Daniel T. Ingersoll, a researcher of Oak Ridge National Laboratory, USA argues that that the SMRs which are presently in the making – like NuScale, mPower and W-SMR – have enhanced safety features and robustness. He corroborates this with a rationale that unlike the conventional reactors, the SMRs have a simplified design in which most of the primary system components (that makes heat energy and subsequently the steam) are contained within a single vessel. Such an integral feature rules out accidents owing to pipe-break loss-of-cooling. According to IAEA, since SMRs relies more on passive systems (that works on its own based on gravity, natural circulation, convection, etc.) and inherent safety aspects, they are much safer. These increased safety margins, IAEA adds, ensures no or negligible radioactivity release to the environment and public even in case of an accident.
Status of SMRs
Currently only two SMRs (35 MWe each and floating type), belonging to the Russian Federation, are in operation worldwide. Besides that, over 70 commercial SMRs are being developed and countries such as USA, Russia, Canada, China, South Korea and Argentina are at the forefront in the race.
India sees SMRs as a promising technology in decarbonisation. SMRs will be in addition to the existing fleet of traditional nuclear power plants and their expansion plans. In his presentation at the IAEA in Vienna, in 2019, Shri. Alok Chaurey of Bhabha Atomic Research Centre (BARC), a premier multi-disciplinary nuclear research institution of India, has stated that the conceptual design of such innovative reactors is in progress and the research and development in this regard have already been kick started. According to India’s largest power producer the National Thermal Power Corporation (NTPC), a joint report by BARC and NTPC on design, development and deployment of SMRs has already been submitted. Like it is being attempted in America, India also is reportedly planning to establish SMRs in the old or retired thermal power plants where the basic necessities such as infrastructure, grid etc. exist.
Like the world moved from big television sets to small flat screens, like the world moved from room-sized massive computer systems to thin laptops, and like the world moved from 10-inch-long mobile phones to slender smart phones, the nuclear power industry, too, is gearing up to go through a miniature revolution to meet the carbon reduction goal. And the nuclear community is hastening to bring SMRs into use.
J. Devaprakash is the Deputy General Manager at the Tarapur Atomic Power Station in Maharashtra, India. He writes about nature, nuclear energy, communication and management…
