POWER MARKET DEVELOPMENTS | SMALL MODULAR REACTORS


Very high temperature reactors


Gas-cooled fast reactors Molten salt reactors


Supercritical water-cooled reactors Sodium-cooled fast reactors Liquid metal cooled reactors


Right: Temperature (°C) of SMR designs and their corresponding non- electric applications Source: Adapted from IAEA ‘Advances in Small Modular Reactor Technology Developments, 2020 Edition


Water cooled reactors 100


200 300 400


District heating Seawater desalination


Pulp & paper manufacture


Methanol production Heavy oil desulfurisation


Petroleum refining Methane reforming hydrogen production Thermochemical hydrogen production Coal gasification Blast furnace steel making 500 600 700 800 900 1000 1100 1200 (˚C)


V However, whether SMRs will become an important part of worldwide energy supply is not yet known. The challenges that must be addressed if SMRs are to become a game-changing scenario for nuclear energy


globally are: ● A clear demonstration of the safety improvements and other benefits offered by SMRs


● A convincing case for competitive economics — both per kW installed and per kWh produced


● An improved international regulatory system enhancing licensing and oversight while building public and political support


● Credible spent fuel management strategies, including national deep geological repositories, multinational disposal options and options for ‘take back’ of spent nuclear fuel (SNF) by suppliers


● Demand for SMRs (producing electricity, process heat or hydrogen) that is large enough to support ‘production line’ factory fabrication


● Political, financial, regulatory, and organisational support from governments for first of a kind SMRs.


Improvements offered by SMRs The principal technical challenge for any nuclear power reactor is to achieve a very strong safety performance, so that the likelihood of accidents is small and the consequences of an accident can be managed. The new SMR reactor concepts aim to achieve this through a design that is shown to be acceptable based on a combination of experimental evidence, analyses, test performance and operating experience with systems similar enough to provide assurance. There is evidence, based on extensive experience with


operating large reactors, that most of the SMRs will be significantly safer than existing reactors.


20 | April 2022 | www.neimagazine.com


The general broad features enhancing safety are clear.


The SMRs’ smaller size means there is much less waste heat to remove and much less radioactivity to manage during accident conditions. Advances in system configurations and control systems make the SMRs much easier to control. Fewer (and in some cases no) operator actions are required for control. SMR designs typically use passive features to accomplish safety functions, so there are fewer active systems that might fail (and in some designs there are no active systems). In some SMRs, passive systems allow the reactor to achieve a safe shutdown state without active intervention by either hardware or operators. SMR designs take advantage of advanced technologies (better materials, more reliable equipment, advanced sensor technologies for monitoring plant status, artificial intelligence technologies). Finally, SMRs will be more easily inspected and repaired


because convenient inspection and repair are typically among the design criteria; and factory fabrication will provide better quality control, less variability between modules, and hence more predictable operating parameters. What is more, emergency preparedness offsite will be


less difficult because the potential accidents will have offsite impacts that are smaller and more localised. Further advantages that can ease siting requirements


are the smaller facility footprint and the lower radioactivity inventory. For some SMRs, there will be less complex and less costly spent-fuel and radioactive waste storage burdens. An important additional positive feature of SMRs is that, because of their modularity and versatility, they may be more easily integrated into energy systems based largely on renewable energy. When considered together, the numerous different safety


improvements and advantages should ease the public acceptance of these new SMRs in many places.


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