Energetic Analysis of Experimental Behavior of Molten SnxLiy When Impacted by a Vertical Column of Water
Abstract The SnxLiy and PbxLiy, alloys are being considered as liquid breeding materials for fusion reactor applications. Thus, it is important to understand the safety implications associated with inadvertent contact with water used in an indirect cycle. In an effort to study this interaction, experiments have been conducted with these molten alloys when impacted with a vertical 2.4-m-tall column of water at 30 and 60°C. The qualitative behavior of Sn75Li25 was compared under similar conditions with other candidate molten metals, specifically tin, lead, and a lead-lithium alloy, Pb83Li17. Multiple pressure spikes were produced with Sn and Pb, while essentially only one initial pressurization followed by a few strongly damped minor peaks was observed with the different alloys containing lithium. Results with tin-lithium are quite similar to pure tin and lead behavior. Dynamic pressure traces from the physical and chemical reactions are discussed and used to compare the energetics associated with the two different alloys. The pressure traces were used to calculate experimental impulses, which represent the energetics of the reactions. The impulse ratio of the experimental and the theoretical values increased in the tests of alloys containing lithium. (Hydrogen production from lithium-water reactions was quite rapid and copious.) In contrast, hydrogen production with tin-lithium was modest and quite similar to the lead-lithium alloy. It was found that the metal-water interactions of Pb83Li17 and Sn75Li25 are quite similar and have significantly reduced energetics from those of pure lithium and other reactive metals being considered.
Liquid-Metal/Water Interactions in a Shock Tube
To investigate liquid-metal (fuel)/water (coolant) interactions, a vertical shock tube has been designed and constructed. A series of tests was conducted with gallium, indium, lead, and tin as the fuel materials at either low (T f ∼ 300°C) or high fuel temperature (T f ∼ 600°C), with water at room temperature (low T c ) and in the range of T c = 56 to 67° C (high T c ), and with driving pressures from 0.25 to 1.22 MPa. These materials were tested to determine their compatibility for potential use in liquid-metal divertor systems for fusion power plants. The increase in fuel and water temperature, as well as the increase of driving pressure, caused more energetic interactions to occur. High T f tin and lead interactions, and high T f and T c gallium and indium interactions were the most energetic. Stronger interactions produced finer debris fragments. In high T f gallium and indium interactions, small superficial oxidation was observed. For the first two pulses, larger ratios of compression- (compression of expansion vessel gas) to-expansion work correspond to the experiments with higher fuel and coolant temperatures. For the first pulse, only work ratio values of the most energetic experiments are larger than those of isothermal experiments. Consequently, for such experiments, the impulse values of second pulses are the largest. Higher values of the conversion ratio for the first pulse correspond to more energetic interactions. Even for the most energetic experiments, the conversion ratio is no higher than 1.2%, and no more than 15% (or a few millimetres-thick surface layer) of the initially loaded fuel participated in the interaction, assuming equal initial volumes of fuel and coolant.
The Materials Impact on Fusion Reactor Safety
AbstractSeven potential safety concerns for deuteriumtritium fusion reactors were examined and the influence of blanket material choice determined. This influence was quantified in terms of relative consequence indices (RCIs) according to prescribed consequence criteria.Selected combinations of structural material (Type 316 stainless steel, HT-9, vanadium alloy, or TZM), primary coolant (pressurized water, helium, lithium, or flibe), and tritium breeder (LiAlO2, lithium, or Li17Pb83) were examined. The analyses and indices were structured to focus on the specific material properties that influence the results, which allows for comparison of materials not included in the present study.The safety concerns that were found to be relatively insensitive (differing by less than an order of magnitude) to material choice are the rate of temperature increase from continued plasma heating following loss of coolant and electromagnetic effects of plasma disruptions. The range of the RCIs was about an order of magnitud...