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The structure–activity relationship is a cornerstone topic in catalysis, which lays the foundation for the design and functionalization of catalytic materials. Of particular interest is the catalysis of the hydrogen evolution reaction (HER) by palladium (Pd), which is envisioned to play a major role in realizing a hydrogen-based economy. Interestingly, experimentalists observed excess heat generation in such systems, which became known as the debated “cold fusion” phenomenon. Despite the considerable attention on this report, more fundamental knowledge, such as the impact of the formation of bulk Pd hydrides on the nature of active sites and the HER activity, remains largely unexplored. In this work, classical electrochemical experiments performed on model Pd(hkl) surfaces, “noise” electrochemical scanning tunneling microscopy (n-EC-STM), and density functional theory are combined to elucidate the nature of active sites for the HER. Results reveal an activity trend following Pd(111) > Pd(110) > Pd(100) and that the forma?tion of subsurface hydride layers causes morphological changes and strain, which affect the HER activity and the nature of active sites. These findings provide significant insights into the role of subsurface hydride formation on the structure–activity relations toward the design of efficient Pd-based nanocatalysts for the HER.

The crystallization and the hydrogen absorption properties of a Ni32Nb28Zr30Fe10 melt spun ribbon were investigated. X-ray diffraction measurements reveal that a small fraction of the ribbon is in a crystalline state, whereas the main component is amorphous. The bulk crystallization process of the alloy ribbon occurs in two steps above 770 K, as measured by differential scanning calorimetry. At each step of the crystallization process, an unusually low activation energy of the order of 180 kJ/mol, was observed. Hydrogen absorption pressure-composition isotherms measured between 598 K and 673 K showed that the enthalpy of hydrogenation is quite high (~85 kJ/mol), as compared to that of analogous ribbons. The isotherms of these ribbons do not exhibit any plateau, similarly to other amorphous materials, but they exhibited extremely slow kinetics for hydrogen absorption. To simulate the local atomic structure involving cluster formation in amorphous Ni32Nb28Zr30Fe10 alloy, DFT-MD approach was used to construct an amorphous supercell of this alloy with 108 atoms. Calculations predicted that a fully amorphous structure of Ni32Nb28Zr30Fe10 can form. The low activation energy of crystallization observed before hydrogenation is due to the presence of only 3 full icosahedra without any Ni-centered icosahedra, that could provide resistance against crystallization. Moreover, a cluster analysis of the Ni32Nb28Zr30Fe10 alloy after hydrogenation showed interaction of hydrogen atoms with only two icosahedra out of four found in this case, and this could be the probable reason for the extremely slow kinetics of hydrogen absorption.

In recent works, it was noticed that Mg/MgH2 mixed with additives by high energy ball milling allows temperature reductions of H2 absorption/desorption without necessarily changing thermodynamic properties. Thus, the objective of this work was to investigate which additives, mixed in low fractions with MgH2 powder would act as efficient hydrogen absorption/desorption catalysts at low temperatures, mainly at room temperature (RT). MgH2 mixtures with 2 mol% additives (Fe, Nb2O5, TiAl and TiFe) were prepared by high energy reactive ball milling (RM). MgH2–TiFe mixture showed the best results, both during desorption at 330 °C and absorption at RT. The hydrogen absorption was ≈ 2.67 wt% H2 in 1 h and ≈ 4.44 wt% H2 in 16 h (40% and 67% of maximum theoretical capacity, respectively). The MgH2–TiFe superior performance was attributed to the hydrogen attraction by the created high energy interfaces and strong TiFe catalytic action facilitating the H2 flow during Mg/MgH2 reactions.

Ti3Sb and Ti3Ir adopt the A15 (Cr3Si type) structure and are reported to incorporate hydrogen atoms to an extent, respectively, of Ti3SbH∼3 and Ti3IrH3.8. First-principles electronic structure calculations were performed to identify factors contributing to the difference in maximum hydrogen composition for these two intermetallic compounds. Relative energies and changes in energy densities of states and crystal orbital Hamilton populations upon H insertion in the intermetallic compounds were examined. In both compounds, hydrogen atoms are attracted to [Ti4] tetrahedral interstitial sites over any others. The natures of metal-hydrogen and metalloid-hydrogen bonding and the effects of hydrogen insertion on metal-metal and metal-metalloid bonding have an influence on the maximum hydrogen contents for Ti3Sb and Ti3Ir.

Considerable fluctuations in the cathodic protection potential under the impact of stray currents lead to the occurrence of local corrosion on steel structures operated in soils and seawater. The potential fluctuations induced by both alternating and direct current sources can be simulated by cycling a square potential step. This paper covers the impact of sign-alternating cyclic polarization (SACP) on the general and local corrosion of carbon steel in 3.5% NaCl solution containing a borate buffer (pH 6.7) and without it. A decrease in the cathodic half-period potential (Ec) of SACP inhibited the general corrosion and accelerates the local corrosion of steel in both solutions, which was associated with an increase in the amount of hydrogen in the metal. Increasing the duration of the SACP cathodic half-period increased the pit density and total area at less negative Ec values. At more negative Ec values, an increase in the duration of cathodic polarization reduced the intensity of steel local corrosion in the unbuffered chloride solution. This effect is explained by blocking of the pit nucleation centers on the metal surface by a layer of steel dissolution products formed in the near-electrode electrolyte layer with a high pH. The combined body of data shows that hydrogen absorption by the metal determines the corrosion behavior of carbon steel under the impact of SACP in chloride solutions, which should be taken into account in the development of models of the corrosion of steel structures under the action of stray currents.

This paper seeks to present notable insights into the catalytic behavior of a ferroelectric BaTiO3 nanomaterial at the boundary plane in the separation of MgH2 starting from 185 °C. The synergy bet...

Compression tests were performed at room temperature to investigate the effects of hydrogenation temperature on compressive properties of Ti6Al4V alloy treated by continuous multistep hydrogenation treatment (CMHT). Pressure-composition isotherms and microstructures were also studied. Results showed that the equilibrium hydrogen pressure increased, and the hydrogen absorption rate decreased with the increase of hydrogenation temperature. The amounts of β phase and α” martensite increased first and then decreased when Ti6Al4V alloy was treated by four times CMHT with the increase of hydrogenation temperature. Hydrogenation temperature played a different role on the compressive properties of CMHT-treated Ti6Al4V alloy. The ultimate compression of Ti6Al4V alloy treated by 11 times CMHT at 850 °C increased by 83.3 % as compared to the as-received Ti6Al4V alloy. The compressive properties of Ti6Al4V alloy were dependent on the amounts of different phases and microstructures when Ti6Al4V alloy was treated by CMHT at different temperatures.

Scaling-up of a 5 kg LaNi5 reactor i.e. Reference Design (RD) with 88.9 mm outer diameter (OD) and 10 conical copper fins embedded with 6 cooling tubes to a 25 kg one is studied through simulations. RD takes 585 s for 90% saturation during hydrogen absorption at Ps = 15 bar and 5 LPM water supply (20 °C). Decreasing tank OD and increasing the number of fins result in the best performance. A scaled-up design with tank OD = 114.3 mm and 60 fins exhibits 57–58% reduction in saturation time (695 s), versus a proportionally-scaled-up design (dimensions of RD increase proportionally) with tank OD = 141.3 mm and 10 fins. Five units of RD connected in series reduce saturation time by ~60% (670 s). Series/parallel configurations can match the RD performance, reduce shutdown risk, offer flexibility in operation, configuration and ease of maintenance.

To obtain good economic and environmental benefits, LaMgNi3.6M0.4 (M = Al, Mn, Ni, Co, Cu) alloys are investigated for the hydrogen storage. The absorption data of hydrogen in the tested alloys are measured experimentally at 373 K. The hydrogen absorption isotherms are analyzed using three models derived from statistical physics formalism. The adequate model permits to discover significant details about the absorption phenomenon via determining the density of the interstitial sites (Dm), the number of hydrogen atoms per site (n) and the energetic parameter ΔE. The results indicate that multi-atomic (n > 1) and multi-linking (n

The H contents and H embrittlement (HE) of Zn- and ZnNi-electrodeposited SCM435 bolts were quantitatively evaluated before and after baking. The Zn-coated bolt possessed higher H contents than the ZnNi-coated bolt in as-electrodeposited and baked states. H atoms were strongly trapped inside the coating layers. The Zn-coated bolt underwent flaking of coating layer during baking at temperatures above 200 °C due to H effusion through the brittle δ phase. The Zn-coated bolt exhibited no HE regardless of baking despite of its high H content due to no permeation of H into the steel substrate during electrodeposition and tensile deformation.

Canadian Nuclear Laboratories has an on-going Research & Development program to support the development of a scaled–down 300 MWe version of the Canadian Super-Critical Water Reactor concept. The 300 MWe and 170–channel reactor core concept uses low enriched uranium fuel and features a maximum cladding temperature of 500 °C. Our goal is to test surface-modified zirconium alloys for use as fuel cladding. Zirconium alloys are attractive as they offer low neutron cross section thereby allowing the use of low enriched fuel. In this paper, we report on the results of general corrosion experiments used to evaluate chromium-coated zirconium-based alloys in the two chemistries (630 μg/kg O2 in both de-aerated and lithiated supercritical water). These experiments were conducted in a refreshed autoclave at 500 °C and 23.5 MPa. After exposure, the weight gain and the hydrogen absorption were examined. At adequate coating thickness, longitudinal and transverse coupons show similar corrosion behavior with improved corrosion resistance compared to uncoated coupons. The measured concentrations of hydrogen absorption are higher for the transverse coupons. Alkaline treatment resulted in higher weight gains than was found in pure oxygenated supercritical water.

Hydrogen embrittlement leads to time-dependent failure of structural components. Hydrogen absorption and diffusion contribute to the time dependency and are often treated by thermodynamic diffusion...

Herein, the influence of Ti substitution on microstructure and hydrogen absorption behavior of annealed ZrxTi7-xV5Fe (x = 0, 0.3, 0.9, 1.5 and 2.1) alloys is systematically studied. The results reveal that the Ti-substituted alloys contain only α-Zr and C15–ZrV2 phases, where the content of C15–ZrV2 phase initially increased with increasing Ti content, followed by a gradual decrease. On the other hand, the content of α-Zr phase decreased with increasing Ti content, and then increased. Hence, the cell volume of C15–ZrV2 phase is maximum and the cell volume of α-Zr phase is minimum at x = 1.5, corresponding to Zr5.5Ti1.5V5Fe alloy. Moreover, the results exhibit that the plateau pressure of α-Zr phase increased with increasing Ti content at 623 K, 673 K and 723 K, whereas the plateau pressure of C15–ZrV2 phase exhibited the reverse change. Also, the stoichiometric ratio (A/B) of A-side element to B-side element in α-Zr phase gradually decreased with increasing Ti content, whereas the C15–ZrV2 phase exhibited an opposite trend. One should note that the A/B stoichiometric ratio may play a critical role in determining the plateau pressure of both phases. The hydrogen absorption curves of ZrxTi7-xV5Fe alloys showed that the hydrogen absorption content increased with increasing Ti content. It should be noted that the hydrogen absorption kinetics decreased with increasing Ti content, which may be mainly caused by increasing of the particle size with increasing Ti content.

This study investigated the non-equilibrium hydrogen absorption reaction paths of the AB5-type LaNi2Co3 alloy using time-resolved in situ synchrotron X-ray diffraction. Diffraction data were collected every second for reactions under two hydrogen loading pressures. Hydrogen absorption with a hydrogen loading of 1 MPa rapidly transformed α phase to a transient phase (estimated to be LaNi2Co3H3.1–3.6, named γ∗); this has not previously been observed under equilibrium processes. The γ∗ phase continuously transformed into the γ phase (LaNi2Co3H4.5–5.0), and the β phase (LaNi2Co3H~3.6) was not formed. When 0.18 MPa of hydrogen was loaded, initially, the γ∗ phase appeared, followed by the formation of the β phase, finally transforming into the γ phase. These results indicate that a higher loading pressure promotes the formation of the γ∗ phase and assists its continuous transformation into the γ phase by enhancing the dissolution of hydrogen into the α and γ∗ phases.

The hydrogen getter consisting of 1,4-bis­[phenylethynyl]­benzene (DEB) and a carbon-supported palladium catalyst (Pd/C) is limited by its powder forms in practical application. Development of the molded DEB-Pd/C is thus highly demanded. To solve the contradiction between molding and hydrogen-getter rate, herein, we prepared a porous polymer matrix composite for DEB-Pd/C by a facile one-phase removal method of their cocontinuous polymer matrices. Such a porous composite exhibits excellent hydrogen-getter activities. More interestingly, under low hydrogen partial pressure, the porous composite had a faster getter rate than that of powder getters. The significantly enhanced activity is attributed to the confinement effects of the continuous pore structure of the polymer frameworks, which further indicates its promise as a highly active and flexible supporting framework for hydrogen absorption or other gas–solid reactions.

Hydrogen absorption leads to redistribution of the components of the surface layer of the amorphous alloy Fe73.8Si12.7B9.4Nb3.2Cu noncontact side, while the amorphous structure of this layer is preserved. The type of the micro-groups Fey Six changes in such a way that the ratio y: x decreases (to less than 1) and the chemical bond polarity decreases, as well. After degassing, the surface layer composition becomes similar to those before hydrogenation. The loss of the mechanical stability of the amorphous ribbon is accompanied by the formation of the micro-groups Fey Six with a decreased ratio of y: x.

In this study, the sulfide stress cracking (SSC) susceptibility of high-strength low alloy steels was investigated quantitatively. Double cantilever beam tests were used to evaluate the effects of environmental factors, namely pH, H2S partial pressure, and temperature, on the SSC. The corrosion rates and the absorbed diffusible hydrogen concentration were also determined. The critical stress intensity factor (KISSC), which signifies the SSC susceptibility, was mainly affected by the H2S partial pressure and the temperature. Even though the solution pH apparently affected the corrosion rate, the influence of pH on KISSC was small. Considering these results, the environmental contribution in each elementary process of the SSC phenomenon was discussed. The estimated local hydrogen concentration at the crack tip area, which clearly depends on H2S partial pressure and temperature, showed good correlation to the KISSC obtained in various sour conditions.

In this work, absorption/desorption isotherms of the LaNi3·6Mn0·3Al0·4Co0.7 alloy, have been determined from the experimental data at three temperatures (TFluid = 298 K, TFluid = 303 K, and TFluid = 313 K). However, the experimental isotherms are compared with a proposed theoretical model. The physicochemical parameters of the proposed model are determined from the experimental data. Using these parameters, the absorption and desorption processes of hydrogen by the LaNi3·6Mn0·3Al0·4Co0.7 alloy can be compared. During the absorption/desorption process, the behaviors of each parameter are studied under the effect of temperature and pressure. In addition, internal energy, entropy, and enthalpy are calculated by using the proposed model. On the other hand, the temperature and pressure effects on the variation of these functions have been studied. The calculated physicochemical parameters suggested that the hydrogen absorption/desorption process in the LaNi3·6Mn0·3Al0·4Co0.7 alloy was feasible, spontaneous and exothermic in nature.

The 13HFA corrosion- and cold-resistant steel is studied by an ultrasonic method after hydrogen absorption for 96, 192, and 288 hours. Within the framework of classical flaw detection, it was found that the formation of macrodefects occurs only at 288 hours of hydrogen absorption. In the study of the material by the spectral-acoustic method, it was found that, during hydrogen absorption for 96 and 192 hours, the signal spectrum changes. This indicates the formation of microdefects. It is shown that the determination of the damage by the conventional ultrasonic flaw detection method and the use of the spectral-acoustic method for the evaluation of fracture at the microlevel give more complete information on the state of the investigated alloys.

In this study, the effect of hydrogen on the phase separation of TiZrNbTa high-entropy alloy (HEA) was investigated. When hydrogen was absorbed, phase separation from single body-centered cubic (bcc) phase into a composite of nanoscale Nb(Ta)-rich bcc phase (BCC1) and Ti(Zr)-rich bcc phase (BCC2) was observed. The high resolution transmission electron microscopy (HRTEM) observation showed that the BCC2 phase followed an orientation relationship of (110)BCC2//(110)BCC1, [001]BCC2//[001]BCC1 with BCC1 phase. A coherent BCC1/BCC2 interface together with interface dislocations were also observed. After hydrogen desorption, the separated phases still existed. The mechanism for the hydrogen-induced nanoscale phase separation in TiZrNbTa was discussed.

In this work, hydrogen isotopes in the form of protium and deuterium were rapidly desorbed from magnetic-hydride iron oxide-palladium (Fe2O3-Pd) hybrid nanomaterials using an alternating magnetic f...

In light metal hydroxide systems, hydrogen desorption generally occurs in exothermic reactions; therefore, these reactions are irreversible in principle. However, according to theoretical calculation of thermodynamics, some of these systems can desorb hydrogen in endothermic reactions. In this research, several hydroxide systems were studied to clarify the reversibility of these systems. Six types of hydroxide systems (XH + Y(OH)(n), X: Li, Na, Y: Li, Na, Mg) were prepared by ball-milling, then the desorption properties of these systems were evaluated. As a result, NaH + LiOH and NaH + NaOH systems desorbed hydrogen in endothermic reactions. Also, NaH + NaOH system absorbed hydrogen almost 100% reversibly under 300 degrees C and 1.0 MPa H-2 pressure. The reversibility in NaH + LiOH system was not accomplished in our experimental condition, because high pressure of GPa order is required for the rehydrogenation. In order to modify the desorption kinetics, we added KH catalyst to NaH + LiOH and NaH + NaOH systems. The hydrogen desorption temperature of the two systems was decreased by addition of 1 mol% of KH. The catalytic effect on hydrogen desorption properties was sustained even after the rehydrogenation of KH-added NaH + NaOH system.

The influences of Gd and Co co-substitution for La and Ni on phase structures, and electrochemical properties of La0.83-xGdxMg0.17Ni3.35-2xCo2xAl0.15 (x = 0-0.83) alloys were investigated. All the alloys contained A2B7-type (Ce2Ni7- and Gd2Co7-type) phase, Pr5Co19-type phase, PuNi3-type phase and CaCu5-type phase. The partial replacement of Gd and Co for La and Ni increased the phase abundance of the Ce2Ni7-type superstructure and decreased cell volumes, which contributed to a better hydrogen absorption capacity, cyclic stability and HRD. Compared to those of single Gd- or Co-substitutions, the synergistic effects of Gd and Co on the overall electrochemical properties of alloys were significant. Such a superior overall electrochemical performance may result from appropriate cell volumes and anti-pulverization abilities.

A series of cubic TbMgNi4-xCox (x = 0–4) pseudo-binary compounds have been synthesized by either a solid-state reaction or mechanical alloying with further annealing treatment. Their hydrogenation properties have been studied by pressure–composition–temperature (PCT) measurements, showing the formation of α-, β-, and γ-hydrides. The Co for Ni substitution yields a lowering of the equilibrium pressure and an increase of the hydrogen capacity. An improvement of the kinetics of hydrogen absorption was observed with an increasing Co content. β-TbMgNi4-xCoxH∼4 (x = 0–3) hydrides show an orthorhombic distortion (Pmn21 space group), whereas the β-TbMgCo4H3.3 hydride crystallizes in a monoclinic structure (Pm space group) derived from the orthorhombic structure. Sensitivity of the formation of the β-TbMgCo4H3.3 hydride to temperature has been observed in PCT curves to exist below 50 °C. γ-TbMgNi4-xCoxHy (x = 2–4, y > 5) hydrides preserve the parent cubic structure (F43m space group) with a hydrogen-induced volum...

Melt spinning technology was applied to prepared La1-xPrxMgNi3.6Co0.4 (x = 0–0.4) alloys, and phase composition, micro-structure, morphology and hydrogen storage properties were systematically investigated. The results show that the alloys contain two phases, LaMgNi4 and LaNi5 which have been detected by XRD and SEM. The grain of the alloys is refined by increasing Pr content and the phase abundance changed obviously. The hydrogen absorption capacity (wt%) of the alloys is 1.663, 1.659, 1.60, 1.593 and 1.566, corresponding the Pr substation of x from 0 to 0.4. The hydrogenation cycle stability indicates that the hydrogen capacity declined severely with the hydrogenation cycles. It is attributed to the hydrogen-induced amorphization which is confirmed by the XRD results after hydrogenation cycles. In order to recover the hydrogen storage capacity after cycles, the annealing treatment at 673 K for 3 h was carried out. And the XRD and HRTEM results show that the amorphization structure after hydrogen absorption/desorption cycles is re-crystallized by annealing treatment.

Experimental studies of the distribution of hydrogen in metal samples after a standardized saturation procedure in a neutral solution are described. It is shown that the hydrogen concentrates in a thin surface layer which plays the role of a shield for the further propagation of hydrogen. We refer to this phenomenon as a skin effect in the hydrogen saturation since the internal regions of the metal are not saturated by hydrogen. A review of similar experimental results for other standardized methods for saturation of metals with hydrogen (cathodic polarization, saturation in gaseous hydrogen) is provided, and the universal nature of the skin effect for metals is shown. The analysis of mechanisms of the skin effect is carried out by methods of continuum mechanics based on a bi-continual model of a solid. The problem of saturating a metal sample with hydrogen without external load is posed. It is shown that the model taking into account the mutual influence of hydrogen and mechanical stresses allows one to obtain solutions describing the highly non-uniform distribution of hydrogen at standardized saturation.

Lithium was added to the hypereutectic Mg–Ni alloy to investigate the effect of volatilization of Li on the hydrogen storage characteristics of the eutectic Mg–Ni alloy at 300 °C. After fully activated at 300 °C, Li was almost completely volatilized and the structure of Li-containing Mg82Ni18 alloy was converted to the structure of Li-free Mg82Ni18 alloy, but hydrogen absorption capacity significantly decreased. This is because volatilization of Li weakened the bonding between eutectic Mg and Mg2Ni, lowering the catalytic effect of Mg2Ni on Mg. The decrease in hydrogen absorption capacity was more obvious with increasing Li content. In addition, experimental alloy in powder form could increase surface area, causing Li to volatilize at 300 °C.

Transition metals, including Ni, show good catalytic activity in the hydrogen storage reaction of Mg. In the present paper, first-principles calculation is performed to predict and analyze the hydriding reaction of Ni-incorporated Mg and experimental study is used to verify the accuracy of the forecast. Theoretical studies show that the hydriding reaction of Ni-incorporated Mg is a diffusion-controlled process. With Ni incorporation, the energy barrier of H2 dissociation is significantly decreased and the diffusion becomes the limiting step. Experimental studies confirm the results of theoretical studies. Besides, the material with Ni incorporation shows excellent activation performance and rapid absorption rates, leading to a high hydrogen content of 4.1 wt% in 60 s under 240 °C 3.0 MPa H2 and a low activation energy of 56.1 kJ mol−1 versus 0.4 wt% and 73.5 kJ mol−1 for the material without Ni incorporation. Atomic Ni only plays a role of catalyst.

The effects of hydrogen absorption on the effective magnetization $(4\ensuremath{\pi}{M}_{\mathrm{eff}})$, gyromagnetic ratio $(\ensuremath{\gamma})$, Gilbert damping constant $({\ensuremath{\alpha}}_{\mathrm{G}})$, and the inhomogeneous linewidth broadening $(\mathrm{\ensuremath{\Delta}}{H}_{0})$ in $\mathrm{Py}(x)/\mathrm{Y}$(16 nm)/Pd(15 nm) trilayer films ($x=2$, 3, 5, 8, 10, 20, 40 nm) were investigated with ferromagnetic resonance (FMR), transmission electron microscopy, and vibrating sample magnetometry. In the presence of a hydrogen atmosphere, the samples show a reduction of their FMR linewidth which is found to stem purely from a reduction of the inhomogeneous linewidth broadening. This is attributed to a rearrangement of atoms at the Py/Y interface in the presence of hydrogen, making the Py/Y interface more homogeneous. In addition, a reduction of $4\ensuremath{\pi}{M}_{\mathrm{eff}}$ was seen for all samples in the hydrogen atmosphere which is typical for an increase of the interfacial perpendicular magnetic anisotropy at the Py/Y interface.

We present the results of experimental studies of the effect of hydrogen absorption on the emission properties of a charge source based on carbon nanotubes. It is determined that the emission properties of the source improve considerably after exposure in hydrogen atmosphere at pressure of 100 atm and temperature of 300°С for 2 hours: at voltage of 300 V the current of negative charges increases by 104 times.

Adjusting the charge environment and charge transfer to optimize the hydrogen absorption free energy (ΔGH*) is an effective strategy to improve the intrinsic activities of electrocatalysts toward t...

Production of tritium using a high-temperature gas-cooled reactor (HTGR) has been studied for a prior engineering test with tritium handling and for the startup operation of a demonstration fusion reactor. For this purpose, the hydrogen absorption speed of Zr in a Li-loading rod for the reactor operation is experimentally measured, and an analysis model is presented to evaluate the tritium outflow from the Li rod in a high-temperature engineering test reactor (HTTR). On the basis of the presented model, the structure of the Li-loading rod for the demonstration test using the HTTR is proposed.