SINGAPORE’S PLANS | NUCLEAR DEVELOPMENT
technology, procedures, programmes, control measures, and risks, and act as advisors to the government on nuclear safety matters. Key factors for ensuring safe nuclear energy operation
are strict governance, robust safety procedures, and effective measures. By combining these elements with the latest advancements in nuclear technology and plant design, the probability of nuclear accidents can be significantly reduced.
Bowtie analysis of operating SMRs The operation of a nuclear power plant is associated with several hazards that can have serious consequences for public health and the environment. Natural hazards, such as earthquakes, severe weather, wildfires, and flooding, are well documented. Human errors in nuclear plant design, maintenance, and operation are also reported that can cause the failure of critical equipment. In addition, nuclear power plants are also vulnerable to intentional harm caused by sabotage, terrorism, and cyberattacks. The economic impact of a nuclear disaster can extend beyond the immediate area, causing damage to property, businesses, and investments and can have an impact on the health and well-being of neighbouring communities. This is particularly relevant for neighbouring countries such as Malaysia and Indonesia. Given the consequences, fear of a nuclear disaster can if not managed properly, lead to widespread scepticism of nuclear energy, which can have further societal and psychological effects. Based on the identified hazards and potential
consequences, a qualitative bowtie diagram, Figure 1, provides a visual representation of the potential treats to a nuclear power plant, the potential consequences, and the suggested barriers to prevent or mitigate those consequences.
Comparative analysis on reactor types To further enhance the broad-based control measures depicted in the bow-tie diagram, it is crucial to gather and thoroughly analyse data from past incidents. This process enables the identification of causes of such incidents,
detection of patterns and trends, and development of effective solutions to mitigate the risks. The study aimed to identify the types of reactors that
have contributed the most to nuclear accidents, as well as the common causes of safety system failures. However, the committee noted that such incidents primarily involved large conventional reactors and may not accurately reflect the safety risks associated with the SMRs which Singapore is considering. SMRs are gaining traction as a preferred option in the energy market due to their potential to provide flexible, affordable, and low-carbon energy. However, given their relatively recent emergence and unique design, there is currently limited data available on SMR nuclear accidents. To address this gap, this study relied on a database of nuclear events to expand the available information and develop sound recommendations for the Singapore government. According to the analysis, Pressurized Water Reactors
(PWRs) were found to be the most common type of reactor involved in nuclear events, accounting for 784 (62%) out of 1,256 incidents, followed by Boiling Water Reactors (BWRs) with 382 (30%) events. Further analysis revealed that the causes of nuclear events varied between them. According to this data, design residuals are the leading
cause of nuclear events for both PWRs and BWRs. Therefore, it is important to consider inherently safer designs when setting up SMRs in Singapore, and foreseeable operational risks must be addressed during the design stage. To prevent operator errors, design verification and testing can be conducted to ensure that operations are robust and that systems can safeguard operations from operator error. While Singapore is unlikely to experience natural
disasters such as earthquakes or tsunamis that could trigger a nuclear accident, tremors from earthquakes in neighbouring countries can occasionally be felt on the island. Thus, it is still recommended to design and build SMRs that can withstand tremors and other natural hazards to increase safety margins. This is also a requirement by the Nuclear Regulatory Commission for all nuclear plants in the United States, following lessons from the 2011 Fukushima Daiichi accident.
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Above: SMRs like the BWRX- 300 are an attractive option for low-carbon energy production
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