Investigation of 2LiF-BeF 2 (FLiBe): Salt Transfer, Corrosion Tests and Characterization G. Zheng, B. Kelleher, G. Cao, K. Sridharan, M. Anderson, T. Allen Materials Science Program, Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53706 gzheng@wisc.edu INTRODUCTION 2LiF-BeF 2 (FLiBe) molten salt is being considered as the primary coolant in reactor vessel for the development of fluoride-salt-cooled high-temperature reactors (FHRs) because of its attractive thermo-physical and neutronic properties [1-4]. The molten salt research program at the University of Wisconsin at Madison (UW) has been working on molten fluoride salts for coolant applications for several years [5,6]. Presently, the UW has initiated studies on FLiBe under a U.S. Department of Energy sponsored Integrated Research Project (IRP), in collaboration with Massachusetts Institute of Technology (MIT) and University of California at Berkeley (UCB). The main tasks of UW include salt preparation, purification, and corrosion testing and characterization of structural materials in molten FLiBe salt. Salt loading, purification, and transfer systems, as well as apparatus for corrosion tests have commenced, and testing in surrogate fluoride salt FLiNaK (a LiF, NaF, and KF salt eutectic mixture) has been completed. A temperature gradient rod heater has been designed and fabricated to melt frozen salt in graphite crucible compartments in the downward direction from the top to minimize the possibility of crucible cracking CURRENT WORK I. Salt Transfer Handling FLiBe presents challenges due to the toxicity of beryllium and the hygroscopicity of both LiF and BeF 2 . Therefore, it is necessary to have transfer and handling systems that eliminate any possibility of contact with personnel and are insulated from any air exposure. Furthermore, the entire transfer system must be operated at the temperature higher than the melting point of FLiBe (460°C). The purified FLiBe has to be directly transferred to corrosion test containers through pure nickel tubes that are wrapped with heating wires and thermal insulation. Taking into consideration future plans for in-core corrosion testing in the MIT research reactor, graphite crucibles with six holes (0.405-in diameter) were designed and machined. Purified FLiBe cannot be directly filled into such small holes from storage vessel due to concerns of splattering and accuracy of loading salt in each hole. Therefore, a salt dripping system was fabricated for filling purified FLiBe into graphite crucible holes, as shown in Figure 1. This system is composed of three parts: pure nickel container, pure nickel dripping tube, and a valve to control the dripping rate. Heating wires and thermal insulations were wrapped on nickel container used to melt FLiBe and maintain it in liquid state. The valve, including the handle, nickel rod and a graphite plug, is fixed at the center of nickel container. Rotating top handle to move the graphite plug vertically was used to control dripping rate. Using this system, FLiNaK was successfully filled into graphite crucible holes in a precise manner. Fig.1. Illustration of molten salt dripping system to be used for FLiBe studies: (a) schematic design diagram, and (b) picture of completed salt dripping system inside the glove box. II. Corrosion Tests To closely simulate future corrosion tests in the MIT research reactor for the purposes of evaluating materials corrosion with and without radiation, several preparatory experiments have been performed for out-of-pile corrosion tests. Test salt FLiNaK was successfully filled into the holes of the graphite crucible using the dripping Transactions of the American Nuclear Society, Vol. 109, Washington, D.C., November 10–14, 2013 259 Research by U.S. DOE NEUP-Sponsored Students—I