PRELIMINARY FUNCTIONAL SAFETY ASSESSMENT FOR MOLTEN SALT FAST REACTORS IN THE FRAMEWORK OF THE SAMOFAR PROJECT

In the last decades, the research activity for the development of innovative nuclear systems tries to answer the current needs of safety, reliability and sustainability, including safety assessment and risk analysis. In this framework, the European project SAMOFAR aims at furnishing the experimental proof of concept of the Molten Salt Fast Reactor (MSFR) and its safety assessment at its present conceptual stage. For this purpose, the Integrated Safety Assessment Methodology (ISAM) is selected and analysed as conceptual methodology and a wide survey on risk analysis tools, international standards and best-practices aims at defining an operational procedure suiting MSFR analysis, including functional safety assessments. Well-established practices applying “Functional Safety” to conceptual systems do not exist; therefore this work proposes and uses a new method based on functional modelling and on the Functional Failure Mode and Effect Analysis (FFMEA). This approach allows studying systems with a preliminary design, identifying functions deviations able to compromise safety, listing Postulated Initiating Events (PIEs) and recognizing lack of information, criticalities and necessity of supplementary provisions in the current design. Therefore, this methodology aims at influencing the design from its earliest stages. The paper focuses on the application of FFMEA to the MSFR in normal operation conditions