NUCLEAR DEVELOPMENT | SINGAPORE’S PLANS Causes of system failures Design residuals


Testing & maintenance error Main component failure


Local & global support component failures Procedural error


Testing & maintenance unavailability Operator error Safety culture


Other initating events Previous system failure 0% 5% 10% Boiling water reactor 15% Pressurised water reactor 20% 25%


Above: Analysis of reactor failure modes reveals that design flaws are the most common and sheds light on SMR deployment in densely populated areas like Singapore


SMR retrofitting for Singapore


To ensure the continued safety and reliability of nuclear facilities, as well as to gain valuable experience and test new technologies, the implementation of a pilot project to retrofit SMRs prior to the construction of full-scale nuclear facilities is recommended. By retrofitting SMRs with advanced safety features and monitoring systems, we can evaluate their performance in a controlled environment and make any necessary improvements before scaling up to larger facilities. SMRs require an Emergency Planning Zone (EPZ) with a


radius of less than 0.3 km. The existing power stations in Singapore are located in industrial areas away from densely populated residential areas. The approximate distances between the power stations and the densely populated areas show that any of the three power stations can be retrofitted with SMRs while maintaining a safe distance from densely populated areas. Using Hierarchical Clustering analysis, the Senoko Power Station has been identified as the most suitable candidate for the initial conversion, with the potential to retrofit the other two stations in the future.


The selection of the Senoko Power Station as the primary


candidate for SMR retrofitting is based on several factors, including its age of over 30 years and its reliance on oil that emits high levels of carbon dioxide. After a thorough evaluation of the power station’s various plants, the Hitachi 1983 Steam Thermal Plant, specifically either G7-243MW or G8-250MW, has been identified as the most suitable option for retrofitting with SMRs. To ensure the safe and efficient operation of the retrofitted plant, it is recommended to use an Integrated Pressurized Water Reactor (iPWR) for the project. This type of land-based, water-cooled SMR has a power range of 151 MWe to 250 MWe and can be matched


40 | August 2023 | www.neimagazine.com


with either the G7-243MW or G8-250MW oil-based plant for a one-to-one retrofitting capacity. Several models, including NUWARD, W-SMR, or mPower, are suitable for this project. The retrofitting of SMRs may also present several


construction and operational risks, which can be mitigated through the use of digital twin software and machine learning. The implementation of digital twin software and machine learning to simulate and evaluate the performance of SMRs will be an essential component of the SMR retrofitting process, allowing for thorough testing and optimisation of the technology prior to deployment. Digital twin models can help identify and prevent potential safety hazards, such as runaway reactions or loss of containment, by providing a virtual environment to test and optimize the technology. Machine learning techniques, such as supervised learning, can be utilised to ensure the safe operation of SMRs by detecting anomalies and predicting potential failures. Unsupervised learning, on the other hand, can optimise maintenance and life cycle costing of all equipment by analysing patterns and identifying areas for improvement. Incorporating digital twin software and machine learning into the SMR retrofitting process can ensure the safe and efficient operation of these reactors. This approach will allow us to identify and resolve potential issues early on, minimising risk and ensuring the long-term sustainability of the facility.


Inherent safe design of SMRs Based on comparative analysis, design errors have been identified as the leading cause of nuclear events. To mitigate this risk, it is imperative that the proposed Integrated Pressurized Water Reactor (iPWR) for Singapore is designed to be inherently safe, with a range of advanced features including:


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