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International audience; The international OECD/NEA FIRE (Fire Incidents Records Exchange) Database is one of the nuclear power plant (NPP) operational events Database Projects currently operated under the auspices of the Organisation for Economic Co-operation and Development (OECD) Nuclear Energy Agency (NEA). This Database for the collection of detailed information from fire events at NPPs from fourteen NEA member countries is approaching the end of its fifth phase. The FIRE Database is considered mature enough for applications, with respect to not only deter¬ministic safety assessment but also in fire probabilistic risk assessment.The most recent version of this Database covers more than 500 well documented fire events during all operational phases of the plant life cycle from construction up to the longer duration safe shutdown, as well as a few events from NPP units under decommissioning. The number of recorded events increases continuously within each annual update. The Database structure enables analysts to carry out search queries for different aspects of fire events and allows investigations into even more complex fire scenarios. Various analyses can be systematically performed in an automated manner, from generating different samples up to a more or less complete statistical analysis.This paper presents a brief overview of the application possibilities of the OECD/NEA FIRE Database for supporting NPP operators as well as regulators in assessing fire safety issues.

In this work thermodynamic properties of molten fluoride salts and salt mixtures are investigated. Fluoride salts have advantageous properties to be used in energy producing systems based on the conversion from heat to energy like i.e in Molten Salt Reactors. For this purpose it is very important to have detailed information about the heat capacity of the pure salts and salt mixtures. To get a better understanding about the heat capacity in mixtures drop calorimetry measurements of mixtures of LiF with other alkali fluorides were conducted and compared. The investigation of fluoride salts at elevated temperatures is complicated by the fact that fluoride vapour is aggressive to many materials. In order to protect our sensitive measurement equipment the salt samples were encapsulated in nickel crucibles using a laser welding technique and afterwards the whole nickel capsule was measured. This method was veried by the measurement of unmixed CsF and KF where in both examples an excellent agreement with literature data was obtained. Afterwards various intermediate compositions of the systems LiF-KF, LiF-CsF and LiF-RbF were investigated and a general trend according to the difference in cation radii could be established. In combination with literature data for the LiF-NaF system the heat capacity of the liquid state follows the order LiF-NaF