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One challenge with concentrated solar power (CSP) systems is the potential corrosion of the alloys in the receivers and heat exchangers at high-temperature (700-1000 • C), which leads to a reduction of heat transfer efficiency and influences the systems durability. In this work, a corrosion model has been developed to predict the rates and mechanisms for corrosion of a nickel-based alloy that is in contact with a molten salt heat transfer system. In addition to accounting for heat and mass transfer effects on the corrosion, the model takes into account the electrochemical kinetics. Coupled with computational fluid dynamics (CFD), the local electrochemical environment and corrosion rates in a high-temperature molten salt system can be predicted. The kinetic, heat and mass transfer parameters used in the model are based on experimental studies conducted in a thermosiphon. The immersion cell was designed to expose coupons to the molten salt at isothermal or non-isothermal conditions between 700-1000 • C. The model can predict the effect of thermal gradients between the top and the bottom of the reactor which induce natural convection of the molten salt. The model has been validated against experimental results at different isothermal and non-isothermal conditions and good agreement has been achieved between the model predictions of the corrosion rates and corrosion potentials with the experimental observations.

Six Ni and Fe -Ni based austenitic alloys were exposed to molten LiF -NaF -KF : 46.5 -11.5 -42 mol% salt, commonly referred to as FLiNaK, at 850 C for 500 h. Corrosion was noted to occur predominantly from dealloying of Cr resulting in void formation, an effect that was particularly pronounced at the grain boundaries. Alloy weight-loss due to molten fluoride salt corrosion correlated with the initial Cr-content of the alloys up to a Cr content of about 20 wt%, and was consistent with the Cr-concentrations measured in the salts after corrosion tests. However, in the nominally 20 wt% to 23 wt% Cr containing alloys, this weight-loss correlated linearly with the carbon content of the alloys, due to the formation of chromium carbide phases at the grain boundaries and its subsequent dissolution into the molten salt along the grain boundaries. The Cr-lean intermetallic precipitates found in the alloys were resistant to corrosion in the molten FLiNaK salt.

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Selective pressures (i.e. resource limitation and competitive interaction) that drive the composition of ecological communities vary, and often operate on different ecological scales (ecological variables across varying spatial scales) than observed patterns. We studied the drivers of distribution and abundance of the American marten (Martes americana) and the carnivore community at three ecological scales on a Great Lakes island archipelago using camera traps. We found different drivers appeared important at each ecological scale and studying any of the three scales alone would give a biased understanding of the process driving the system. Island biogeography (resource limitation) was most important for carnivore richness, with higher richness on larger islands and lower richness as distance from the mainland increased. Marten presence on individual islands appeared to be driven by island size (resource limitation) and human avoidance (competitive interaction). Marten abundance at camera trap sites was driven by the cascading effect of coyotes (Canis latrans) on fishers (Pekania pennanti) (competitive interaction). Incorporating three ecological scales gave novel insights into the varying effects of resource limitation and competitive interaction processes. Our data suggests that ecological communities are structured through multiple competing ecological forces, and effective management and conservation relies on our ability to understand ecological forces operating at multiple ecological scales.

An in situ electrochemical probe, utilising anodic stripping voltammetry (ASV), has been developed to measure dissolved Cr concentration in the molten salt LiF- , commonly referred to as FLiNaK. Tests were performed in a glassy carbon crucible in an argon atmosphere glovebox at a molten salt temperature of 650uC. Cyclic voltammetry was performed to determine reversibility and mid peak potential. The Cr 2z /Cr 0 reaction occurred with a mid peak potential of 20?51 V versus a 10 mol.-% Ni 2z /Ni 0 reference electrode. The integrated current from the anodic waves at this potential were used for Cr cation quantification. The integrated current from the ASV measurements correlated linearly with Cr concentration, measured independently using neutron activation analysis, over a range of 30-950 ppm (1?2-38 mmol L 21 ). This study is significant for determining Cr concentrations in high temperature molten FLiNaK salts exposed to Cr containing structural materials.