International Journal of Recent Development in Engineering and Technology Website: www.ijrdet.com (Volume 1, Special Issue 1, Oct 2013) International Conference on Modern Trends in Science, Engineering and Technology 2013 (ICMTSET 2013), Dubai, UAE. Page 1 Mechanical and Chemical Testing of Metallic and Elastic Parts of Gasket in an Environment of Fluoride Salts Pavel Svoboda 1 , Ladislav Snajdarek 1 , Martin Marecek 2 1 MICO spol. s.r., Třebíč, Czech Republic 2 Research Centre Rez, Husinec-Řež, Czech Republic 1 fpsvoboda@mico.cz 2 mma@cvrez.cz Abstract— This paper describes selection of individual components for sealing elements in environment of melted salts. Individual suitable nickel and non-nickel alloys along with flexible elements of the sealing (graphite foil, mica) are described. In conclusion are outlined individual experimental procedures for long-term testing of the selected components. Keywords—fluoride salts, gaskets, graphite, high temperature I. INTRODUCTION The melts of mineral salts are used in many industrial applications e.g. production of very volatile metals like lithium, sodium, rare earth metals, uranium, plutonium or electrolytic metal coating with titanium, tungsten, molybdenum etc. Another important field where melts of mineral salts can be used is the field of cooling media. The melts can be used as heat carrier for some types of reactors or selected salt compounds are used for reprocessing of used nuclear fuel. An example of a nuclear reactor that is using fluorine salts as heat-carrying medium is Molten Salt Reactor MSR. This concept is classified, along with other five concepts of nuclear reactor, as generation IV nuclear reactor and it can be used as breeding or transmuting reactor. While in operation a breeding or generative salt mixture are considered for use. Furthermore, the reactor can be used for electricity or hydrogen production. This is due to its high operating temperature. Feasibility of such concept was verified in the last century in Oak Ridge National Laboratory in USA. A candidate for carrying salt of the primary circuit for the MSR or for transport of high potential heat is LiF-BeF2 (melting point of LiF-BeF2 is ca. 729 K). Alongside its favorable thermo-physical attributes [2], [6], [8] (specific heat Cp ≈ 2400 J/kgK at 973 K , thermal conductivity k ≈ 1 W/mK at 873 K) it also have a very low effective profile for neutron capture when isotope Li-7 is used in the mixture. Pure FLIBE is not particularly corrosive, however addition of oxidizers (e.g. UF4 in the case of fuel salt MSR ) rapidly increases its corrosive potential [1], [5]. A certain disadvantage of this salt is a difficult manipulation due to the presence of toxic beryllium and high cost of Li-7 separation. This is why is sometimes (particularly in the USA) preferred melt FLINAK in the experimental laboratory conditions [2],[9],[10]. However, FLIBE is still considered a reference melted salt for FHR and MSR. Fluoride and its compounds are aggressive substances and strong reducing agents capable of combining with almost every element. This is why it is very important to know mutual interactions of specific medium with every construction material while building any device working with such compounds. Sealing elements are one of construction part of any device and their attributes almost always define operability, lifetime and safety of the device. Experience from operation of many industrial and nuclear facilities shows that the most used and best sealing elements of flanged connections are combined gaskets. These are composed from at least two different materials. One usually is a “matrix” made of strong – metallic material and the other is flexible. While designing a combined gasket it is necessary to know the behavior of each material while interacting with each other and with the sealed medium as well.