[en] The recent High Yield Lithium-Injection Fusion Energy (HYLIFE-II) reactor design employs a curtain of oscillating molten-salt sheet jets to protect the fusion chamber walls. The current literature is inadequate for predicting how well the geometry of these turbulent jets can be controlled in a vacuum environment. Designing such jet systems requires experimental investigation, and this paper outlines scaled experiments to validate HYLIFE-II jet requirements

[en] The objective of this study is to provide as hard-headedly realistic an assessment as possible of the use of flibes for blankets in first generation of fusion reactors. Information concerning what is known and what is needed are provided; solutions of the major problems or what is required to achieve solutions are identified. The problems with using flibes as blanket materials can be divided into two areas: flibe loop inside and flibe loop outside of the blanket region. The problems of the flibe loop inside the blanket region are complicated by such factors as nuclear transmutation and the chemical stability of the flibe under the neturon flux bombardment as well as the effects of the magnetic fields. The problems of the flibe loop outside the blanket region include stripping tritium for the flibe through a stripping vessel and the handling of the off-gases. After reviewing a wide range of tritium separation techniques, fan spray sheet stripping appears to be a practical and attractive technique for use with the first generation fusion reactors using flibes as the blankets. Although some of the problems involved are complicated, they are not insoluble. The author feels flibe is a practicable alternative blanket material for first generation fusion reactors due to its favorable fluid properties and the ease of recovering tritium from it

[en] Fluoride salt-cooled high-temperature reactors (FHRs) are one of the new reactor concepts proposed in the Generation IV International Forum. The main distinguishing features of the FHR are its high operating temperature, lithium beryllium fluoride salt (Li₂Be₄F) coolant, known as FLiBe, and graphite moderator. Most FHR studies focus on the use of tri-structural-isotropic (TRISO) particulate fuels that are compacted with a graphite matrix to form various fuel shapes. Although TRISO fuel offers some potential performance advantages, it is much more expensive than conventional UO₂ fuel. This study investigates the performance potential of pin-type fuel assembly designs in an FHR, by seeking the ideal assembly configuration and the minimum enrichment level needed to achieve a target (13 months) cycle length for a small (125 MWth) FHR, while ensuring that the coolant and fuel temperature reactivity coefficients remain negative throughout the cycle. Three different assembly configurations (with 36, 60 and 90 fuel pins respectively) were analysed using the deterministic lattice physics code WIMS, over a range of ²³⁵U enrichments (from 1 wt.% to 20 wt.%) to investigate the minimum enrichment level. In addition, to estimate the cycle length of the reactor, a leakage probability analysis was performed by modelling a 2D whole-core reactor. (authors)

[en] We have designed a vacuum disengager system to remove tritium from the Flibe (Li₂BeF₄) molten salt coolant of the HYLIFE-II fusion reactor. There is a two-stage vacuum disengager in each of three intermediate heat exchanger (IHX) loops. Each stage consists of a vacuum chamber 4 m in diameter and 7 m tall. As 0.2 mm diameter molten salt droplets fall vertically downward into the vacuum, most of the tritium diffuses out of the droplets and is pumped away. A fraction Φ ∼10^-5 of the 8.6 MCi/day tritium source (from breeding in the Flibe and from unburned fuel) remains in the Flibe as it leaves the vacuum disengagers, and about 21% of that permeates into the intermediate coolant loop, so about 20 Ci/day leak into the steam system. With Flibe primary coolant and a vacuum disengager, it appears that an intermediate coolant loop is not needed to prevent tritium from leaking into the steam system. An experiment is needed to demonstrate Flibe vacuum disengager operation

[en] Various candidate materials have been considered for the tritium breeding material in the Controlled Thermonuclear Reactor system (CTR). Among them, the 2:1 molten mixture of lithium fluoride and beryllium fluoride (2LiF-BeF₂ denoted as Flibe) has many advantages, such as no radiation damage, high chemical stability, easy maintenance, possible use as a coolant and low electrical conductivity to reduce the pressure drop caused by the magnetohydrodynamic (MHD) effect. A model including an isotopic exchange reaction of T⁺, HT, H₂ and H⁺ dissolved in Flibe is proposed to explain the tritium release behavior from Flibe in an in-pile experiment. The temporal change of HT release rate for about two hours after the start of tritium generation observed by the experiment was well reproduced by the model. H₂ supply from the gas phase is a rate-determining mechanism for the isotopic exchange reaction. (authors)

[en] Enhanced safety and performance improvements have been made to the liquid-wall HYLIFE reactor, yielding the current HYLIFE-II conceptual design. Liquid lithium has been replaced with a neutronically thick array of flowing molten-salt jets (Li₂BeF₄ or Flibe), which will not burn, has a low tritium solubility and inventory, and protects the chamber walls, giving a robust design with a 30-yr lifetime. The tritium inventory is 0.5 g in the molten salt and 140 g in the metal of the tube walls, where it is less easily released. The 5-MJ driver is a recirculating induction accelerator estimated to cost $570 million (direct costs). Heavy-ion targets yield 350 MJ, six times per second, to produce 940 MW of electrical power for a cost of 6.5 cents/kW·h. Both larger and smaller yields are possible with correspondingly lower and higher pulse rates. When scaled up to 1934 MW (electric), the plant design has a calculated cost of electricity of 4.5 cents/kW·h. The design did not take into account potential improved plant availability and lower operations and maintenance costs compared with conventional power plant experience, resulting from the liquid wall protection. Such improvements would directly lower the electricity cost figures. For example, if the availability can be raised from the conservatively assumed 75% to 85% and the annual cost of component replacement, operations, and maintenance can be reduced from 6% to 3% of direct cost, the cost of electricity would drop to 5.0 and 3.9 cents/kW·h for 1- and 2-GW (electric) cases. 50 refs., 15 figs., 3 tabs

[en] HYLIFE-II reactor uses molten salt Flibe as the liquid blanket material. The property of its gaseous state was poorly known for gas dynamics calculations and other design problems. This study presents two fitted equations of state of the Flibe gas to meet the needs. The fitted range covers both dissociation and ionization regions. The methods used for fitting allow good agreement between the calculated data and fitted equations

[en] A model for the ionization equilibrium of weakly non-ideal Flibe plasma is presented in terms of a set of coupled non-linear Saha equations supplemented by electro-neutrality and conservation of nuclei. Non-ideality effects have been taken into account in terms of lowering of the ionization potentials and truncated partition functions. A simple formulation and solution strategy of the Saha equations for the single element case has been extended for application to the case of plasma mixtures and has been used to calculate the composition of partially ionized Flibe plasma over a wide range of temperatures and densities. A criterion for the validity of the assumption of local thermodynamic equilibrium is presented and applied to the result. Effects of non-ideality corrections and approximating the partition function to the statistical weight of the ground state have been quantified and presented

[en] A Flibe blanket has been proposed to be used in FFHR. Since Flibe has poor heat transfer performance, heat transfer promoter is required, and a sphere-packed pipe (SPP) has been proposed to enhance the heat transfer performance in the Flibe blanket. In this paper, the fluid flow and heat transfer characteristics in the SPP is evaluated numerically using a k–ε turbulent model for the flow field and an algebraic model for the thermal field. As a result, it was shown that bypass flows in the SPP play a significant role in heat transfer. Also it is thought that the turbulent energy can strongly affect heat transfer performance

[en] A design concept is outlined in this report that utilizes only steady flow Flibe jets, with no moving parts inside the vessel. This design for liquid wall shielding is less complex than our present oscillating flow baseline design. The design avoids the wear and mechanical complexity of moving nozzles or deflectors inside the reactor vessel. Also the attaining of well defined liquid boundaries is less difficult than for the oscillating ''slab'' flow