Small Modular Reactors: a new approach to generating nuclear energy12 December 2018 Read the article
Quicker to build, smaller and more modular, SMRs are an answer to the need for low- or medium-output zero-carbon energy generation in locations that can, at times, be remote. Reliability and safety obviously remain imperatives, but modularity, flexibility, ease-of-build and digitalisation are also avenues that engineers are exploring in their quest for innovative systems that can offer the best solutions for the future.
SMR – three letters that symbolise the new face of nuclear energy. In Europe, nuclear power plants are generally synonymous with large reactors that have outputs of up to 1,600 MW; but in other parts of the world, a large number of SMR projects are under way. There are two main reasons for the growing popularity of SMRs:
- The construction costs of “large” power plants are high and commissioning lead-times long. The capital outlay for this type of plant is therefore significant, which restricts the number of plants that can be built. SMRs – whose costs and lead-times can be much lower – enable more players to invest in the generation of nuclear energy.
- SMRs are particularly advantageous for countries with energy needs in remote areas but where a conventional high-power reactor would not be suitable.
S for “simplicity”, M for “modularity” and “mass-production” and R for “return on experience”
As SMRs have a lower energy output, their architecture is more straightforward than conventional reactors and they could be built using standardised, mass-produced components and systems. This means that they have the potential for shorter construction times and could be less costly to build due to the economies of scale achieved from their mass production.
In addition, as seen in other industrial sectors (such as aeronautics and ship-building), this type of modular design means that the reactor can be split into sub-assemblies that are manufactured and then tested in-factory. As the modules are easily transportable, by road, rail or sea, they can then be rapidly assembled on site.
At Assystem, we have studied the design of condensers in turbine halls by separating them into several modules. This design provides the additional benefit of simplifying maintenance operations as one of the modules can be replaced if it breaks down rather than having to replace the whole condenser. It also results in optimising inventories of spare parts.
Experts in the field agree that the first commercialised SMRs will use PWR technology (Pressurised Water Reactors) so as to leverage the return on experience available from the many reactors that are already based on this technology. For example, it is the case for both EDF in France and Rolls Royce in the UK. These solutions not only simplify the construction of the reactors but also make it easier to incorporate passive safety systems and provide a significant period of grace in the event of an accident.
Making the most of digital solutions
SMRs are an ideal opportunity for putting to use digital solutions such as Building Information Modelling (BIM), which has already been used for constructing complex infrastructure such as Doha airport. Until only recently, digital solutions were hardly used in the design of reactors whereas today we can develop 5D models. The first three dimensions are obviously spatial. The fourth is the time factor – thanks to new technologies we can even simulate the delivery lead-time of a reactor. And the fifth dimension is the financial factor which enables the project’s overall cost to be controlled. All of these parameters mean that we can now anticipate potentially critical moments in each project and therefore more effectively meet investors’ expectations and ward off future problems. For instance, by using digital technologies, we can detect in advance if there is an interface problem between two pieces of equipment and therefore avoid overruns both in terms of costs and deadlines.
These technologies can also create a digital twin of a reactor which is then used to optimise maintenance and refurbishment work as well to prepare for decommissioning when the time comes.
Energy production: an issue for the planet
The ecological potential of SMRs could also be very useful for boosting the image of nuclear power. Because as well as generating electricity, SMRs (PWR technology) could be employed for other purposes such as supplying heat (cogeneration), desalinating seawater or producing hydrogen.
It is also possible to design multi-SMR plants, and because the output of one or more units can be modulated in just a few minutes they can be integrated into a smart grid in order to offset the impact of intermittent supply from renewables without emitting any CO2 (unlike gas power plants).
If we want to commit to no longer producing diesel vehicles by 2040 and meet the undertakings of the Paris climate change agreements by keeping the global temperature rise to beneath 2°C, we need to aggressively pursue energy transition and move towards zero-carbon electricity. SMRs are an excellent backstop for ensuring that by 2030 we will be in a position to switch to clean energy production while being able to meet the higher energy demands that come with rising population numbers.
With the same aim of producing more eco-friendly electricity, SMRs can be used in developing countries which don’t have the electricity grids or consumer demand for higher-level production. SMRs can replace coal or gas-fired power plants to generate zero-carbon electricity.
A further step towards international standardisation
Another advantage of SMRs, especially in relation to the standardised components used in their design, is that it will be easier to introduce a universal set of safety rules applicable worldwide. When a plane takes off from London and lands in Rio de Janeiro, it has to comply with the same aviation regulations throughout the flight, as the aeronautical sector has put in place standardised international rules.
The International Atomic Energy Agency (IAEA) has set up numerous technical thinktanks to address this issue as, for example, UK regulations on fire safety are stricter than those in France. It is high time for everyone to be subject to the same rules.
Such standardisation is important for making the industry simpler – without affecting safety of course –so that SMRs can be developed cost efficiently.
In sum, therefore, SMRs are an excellent opportunity for Assystem to continue to build its skills in the nuclear sector by identifying and creating innovations that will contribute to making the sector more competitive. So, let’s get creative and inventive and draw inspiration from other industrial sectors, such as aerospace, in order to make the dream of new-generation nuclear energy reactors come true.
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