Study of tritium transport characteristics in a transportable fluoride-salt-cooled high-temperature reactor

Abstract

Summary Tritium management is one of the most critical issues that limit the development of fluoride‐salt‐cooled high‐temperature reactor (FHR); therefore, it is important to figure out the tritium transport characteristics in FHRs. In this paper, 3 works concerning about tritium in FHR are conducted: first, the tritium transport characteristics in the primary loop of FHRs are introduced, including tritium production and speciation, the absorption and desorption by graphite, dissolution and diffusion in molten salt, and permeation through structural materials. Second, the physical and mathematical models are established for tritium transport characteristic analysis in a transportable FHR (TFHR). The tritium transport characteristic analysis code (TAPAS) for TFHR is developed and benchmarked. The results prove the fidelity and accuracy of TAPAS. Finally, the tritium transport characteristics in the TFHR are analyzed systematically by TAPAS. Three conclusions are obtained: (1) tritium in the primary coolant loop is mainly in the form of T2; (2) when TFHR operates at steady state, the permeation rate of T2 can be regarded as a constant (9.03 × 109 Bq ⋅ EFPD−1); and (3) 7Li enrichment and redox potential of molten salt have great influence on the tritium distribution. This work might provide contribution to the tritium control in FHRs.

The impact of hydrogen valence on its bonding and transport in molten fluoride salts

“…In some cases, it has even been assumed that D H + > D 0 H , which could cause signicant error in predicting transport behavior. 20,50 From this work, it is clear that experiments that controlled for speciation, impurities, and corrosion produced more reliable data than those that did not, which was supported by simulation results. Further, the simulations provide insights that allowed understanding of transport behavior at the level of local atomic structure, which would otherwise be difficult to infer from experimental data alone.…”

“…At thermodynamic equilibrium, the concentration quotient [H + ]/ [H 2 ] ½ in the molten-salt phase can shi the voltage U of the metal. 20,21 By metal-salt interactions (corrosion or deposition), U can also affect the concentrations of other charge-neutral or charged species (impurities or ssion products) in the melt, which can produce unwanted changes in performance. Thus, the valence-dependent transport and chemical properties of tritium must be precisely quantied and understood.…”

The Impact of Hydrogen Valence on Its Bonding and Transport in Molten Fluoride Salts

“…Conventionally, the differences between the diffusion of H * and H ) in molten salt has been ignored due to a lack of information. In some cases, it has even been assumed that / & > / # , which could cause significant error in predicting transport behavior [46] [47]. From this work, it is clear that experiments which controlled for speciation, impurities, and corrosion produced more reliable data than those that did not.…”

Survey and Assessment of Computational Capabilities for Advanced (Non-LWR) Reactor Mechanistic Source Term Analysis.

“…Many of the models utilized in these codes are documented in the open literature. The Tritium Transport Characteristics Analysis code (TAPAS) was developed by researchers at Xi'an Jiaotong University in China as part of the development of the prismatic-core transportable FHR (TFHR) design [286]. The same researchers also used TAPAS for the solid-fueled pebble bed Thorium-based Molten Salt Reactor (TMSR-SF), showing the integrated theoretical model can be used for various fluoride salt-cooled, solid-fueled designs [287].…”

“…The same researchers also used TAPAS for the solid-fueled pebble bed Thorium-based Molten Salt Reactor (TMSR-SF), showing the integrated theoretical model can be used for various fluoride salt-cooled, solid-fueled designs [287]. They provide details on the models built into the code as well as results from the code on the effect of Li-7 enrichment on tritium production and the effect of redox potential on T2 permeation and Cr corrosion [286].…”