Liquid Metals for Nuclear Applications

Divertor designs involving liquid lithium have been proposed as an alternative to solid designs and wall conditioning techniques. However, Li affinity with tritium poses a risk for the fuel cycle. This study investigates deuterium retention in pre-lithiated samples and LiD co-deposits in the DIII-D tokamak, making for the first time a direct comparison between LiD co-deposits and pre-deposited Li films. Samples were exposed to H-mode plasmas in the far scrape-off layer (SOL), and Li powder was injected in-situ with the impurity powder dropper to study the uniformity of Li coatings, and the dependence of fuel retention on Li thickness. The results show that at temperatures below the melting point of lithium, deuterium retention is independent of the thickness of pre-deposited Li layers, with LiD co-deposits being the primary factor for fuel retention. Both pre-deposited and in-situ deposited Li showed lower erosion than predicted by sputtering yield calculations. These results suggest that fuel retention in fusion reactors using lithium in the divertor will likely be dominated by co-deposits rather than in the divertor itself. If one desires to use Li to achieve flatter temperature profiles, operando Li injection is advantageous over pre-deposited Li films, at least at temperatures below the melting point of lithium.

The processes of atmospheric corrosion of iron and steel and the properties of corrosion products (rusts) are modeled based on a quantitative evaluation of the chemical reactions pertaining to corrosion to elucidate the conditions with which corrosion-protective rust films form. in the initial stage of corrosion, in the rusts, the pH of the aquatic system is maintained at 9.31 owing to an equilibrium with iron (II) hydroxide and the rate of air-oxidation at this pH is very fast, and that dense, self-repairing rust films form, protecting the underlying iron and steel. However, after corrosion stops, the rust film deteriorates due to the dissolution and shrinkage by aging, and the deteriorated rust film separates the anode and cathode reaction products (Fe2+ and OH-ions) to cause crevice corrosion. The air-oxidation of iron (II) in anode channels without the presence of OH-ions results in strongly acidic solutions (pH 1.41), causing acid-corrosion. It is proposed that good catalysts (e.g. copper (II) and phosphate ions) accelerate the air-oxidation at low pH, delaying the creviceand acid-corrosion stages. Further, it is argued that iron compounds with negative charges due to the nonstoichiometric proportions of the lattice oxide ions and metal ions (solid oxoanions of iron) exhibit stable cation-selective permeability even with a drop in pH. Rust films including such compounds would stop the passage of aggressive anions and act to protect iron and steel.

This paper describes the concept and preliminary component testing of a gascooled, UN-fueled, pin-type reactor which uses He/Xe gas that goes directly into a recuperated Brayton system to produce electricity for nuclear electric propulsion. This Direct-Drive Gas-Cooled Reactor (DDG) is designed to be subcritical under water or wet-sand immersion in case of a launch accident. Because the gas-cooled reactor can directly drive the Brayton turbomachinery, it is possible to configure the system such that there are no external surfaces or pressure boundaries that are reffactory metal, even though the gas delivered to the turbine is 11 44 K. The He/Xe gas mixture is a good heat transport medium when flowing, and a good insulator when stagnant. Judicious use of stagnant cavities as insulating regions allows transport of the I 144-K gas while keeping all external suflaces below 900 K. At this temperature super-alloys (Hastelloy or Inconel) can be used instead of reflactory metals. Super-alloys reduce the technology risk because they are easier to fabricate than refractory metals, we have a much more extensive knowledge base on their characteristics, and, because they have a greater resistance to oxidation, system testing is eased. The system is also relatively simple in its design: no additional coolant pumps, heat exchanger, or ffeeze-thaw systems are required. Key to success of this concept is a good knowledge of the heat transfer between the fuel pins and the gas, as well as the pressure drop through the system. This paper describes preliminary testing to obtain this key information, as well as experience in demonstrating electrical thermal simulation of reactor components and concepts.

Heat transfer devices find applications in various aspects of life. Be it residential, commercial or industrial application, efficient heat transfer is a challenge to all. Other than geometric design considerations and wick selection, the optimization of heat transfer in the heat pipe also depends on fluid selection. Heat pipe technology has proven to work efficiently with properly selected thermal fluid, from cryogenic temperatures to very high temperatures. Higher heat transfer ability through small temperature differences makes the heat pipe an efficient technology. Hence, it can be stated that selecting a proper working fluid enhances the heat transfer performance of a heat pipe. For selecting the working fluid, important thermo-physical properties to be considered are density, viscosity, surface tension, latent heat of vaporization and vapor saturation pressure at every working temperature. The operating range of the working fluid starts from the triple point and till the critical point. The performance of the working fluid is not optimum at both ends of the operating range of temperature. At critical temperature, it is impacted by low surface tension and latent heat of vaporization, whereas near the triple point low vapor density and high viscosity affects the performance. One of the first indices for evaluating the performance of the working fluid is called "Merit Number" This merit number considers a single pressure gradient, i.e. the liquid pressure drop. Later, substantial works have been done to implement the same idea in a system utilizing multiple pressure gradients (losses). In all the methods comparing the merit number of the fluids, the higher the merit number, better is the heat transfer capacity of the pipe. DEDICATION This work is dedicated to my family and friends whose unconditional support, love and belief in me, encouraged me in every shape of life. v ACKNOWLEDGEMENT I would like to express my sincere gratitude to my advisor Dr. Jay M. Ochterbeck for his continued and extensive support and relevant feedback throughout the work. vi

Ab~trlct-ln this paper the porous medium concept is adopted to build up a fundamental model for two-phase flows inside mini channels. The capillary force which appears important for those problems is rigorously included in the model by following the same treatment as for porous media. Various applications of the developed model are demonstrated, among which are adiabatic co-and counter-current flows and heated forced and natural convective flows. Some fundamental results such as the two-phase pressure drop in a downflow, the flooding limit in a counter-current flow and dryout heat flux in natural convection boiling, are achieved and compared with previous studies available in the literature. With the main emphasis on the application to micro heat pipes, the model is used to predict the capillary limit of an operating micro heat pipe, to explain the liquid holdup phenomenon and to imply the onset and origin of the plug flow pattern. Future research needs are pointed out to refine this first version of a two-phase model and to apply it to additional practical applications.

This paper presents the results of CFD and thermal-hydraulics analyses of liquid sodium heat transfer in 19 UN fuel rod hexagonal bundles with scalloped walls. These bundles are arranged in three concentric rings in the core of the Very-Small, Long-LIfe, and Modular (VSLLIM) nuclear reactor. The rods are arranged in a triangular lattice with P/d = 1.2 and the scalloped walls ensure same flow area per rod in the bundles, and hence the radial uniformly of the liquid sodium flow for enhanced thermal performance. The analyses investigate the effects of the reactor power, P RX (1.0, 5.0, and 10 MW th) and the fission power distributions in the UN fuel on the radial and axial distributions of the fuel temperatures as well as the axial and radial distributions of the liquid sodium temperature and flow velocity in the hottest bundle in the reactor core. The analyses also calculate the bundle friction factor, f b , and the local Nusselt number, Nu, of liquid sodium along the bundle. The effect of the numerical mesh refinement on the results convergence is also investigated. The obtained values of f b and the fully developed Nusselt at different reactor thermal powers are within ±8% and +0.5 of reported correlations based on extensive CFD and experimental databases. At P RX = 10 MW th , the maximum UN fuel temperature in the hottest bundle in the VSLLIM reactor core is quite low ($811 K), which ensures almost full retention of fission products in the UN fuel and minimal fuel swelling. The corresponding average temperature of the liquid sodium exiting the reactor core is 752 K. This temperature is not only suitable for attaining high plant thermal efficiency ($35-38%), but also compatible with the HT-9 steel cladding and core structure for the long operation lives of the VSLLIM reactor.

Electricity production is a major problem for deep space exploration. The possibility of using radioisotope elements with a very long life as an energy source was investigated in the framework of an EU project “SpaceTRIPS”. For this, a two-stage system was tested, the first in which thermal energy is converted into mechanical energy by means of a thermoacoustic process, and the second where mechanical energy is converted into electrical energy by means of a magnetohydrodynamic generator (MHD). The aim of the present study is to develop an analytical model of the MHD generator. A one-dimensional model is developed and presented that allows us to evaluate the behavior of the device as regards both electromagnetic and fluid-dynamic aspects, and consequently to determine the characteristic values of efficiency and power.

The paper presents experimental investigations on liquid metal (sodium and potassium) heat pipe operating and startup. Thus, is studied the wickless gravity assisted heat pipes, that presents a high non-uniformity of the temperature profile along the entire pipe. Because the temperature increasing of the evaporator lower end, it is compulsory to provide wick in the liquid metal heat pipes. There are recommended composite wicks with grooves and screen, or some screen layers.

co-designer of the Heat Pipe Test Facility (HPTF) and resident expert on data acquisition. Pete Meyer (Meyer's Design Shop), Steve Smith (Radiation Center), and Grant Laiblin (Willamette Hose & Fittings) contributed significantly to the design and construction of the HPTF. I am sincerely thankful for the staff at the OSU NROTC Unit for their unwavering support. CAPT R.E. Curtis, CAPT H.M. Dyck, and in particular, LtCol Barney Grimes were incredibly gracious and supportive in letting me work on this project while teaching at the NROTC Unit. They gave me an opportunity "above and beyond," and I am very grateful.

The open source and freely available fluid flow solver named caffa3d was adapted to simulate the performance of a medium-scale Hydrostatic Pressure Machine (HPM) with straight radial blades, which had been previously tested in a laboratory facility. A fully detailed explanation of the code caffa3d is not intended to be included in this paper, but some of its main characteristics are mentioned for completeness. In addition, convergence and grid sensitivity analysis were performed in order to assess the adequacy of the model. Evolution of instantaneous power over a few turns of the HPM shows typical blade pass frequency for all operating discharges and another oscillatory phenomena at rotating frequency for higher discharges. The Power—Discharge and Efficiency—Discharge curves obtained from the simulations present a good correlation with the experimental curves, up to the discharge value corresponding to the maximum power of the HPM. The comparison error in power and efficiency remain...

Neutronic analysis of a conceptual heat pipe-cooled micronuclear reactor with 70 % enriched uranium nitride fuel is carried out by modeling the core and peripheral control drum movement to estimate the power distribution. The core configuration results in non-uniformities and hotspots. For the heat removal, empirical formulae have been used in the case of sodium, lithium, and potassium working fluids. The neutronic simulation was carried out by the OpenMC code. It has been found that the radial flux peaking as high as ~20 % can occur at various stages of the drum movement. The novelty of this research is the investigation of the effect of variable enrichment on the overall system multiplication, which can form the basis for optimal fuel distribution. It has been found that non-uniform fuel distribution can mitigate peaking factors, and thus reduce the hotspots. This analysis is useful for the design optimization of compact micro nuclear reactors for underwater, portable and space pr...

An advanced radiator concept for heat rejection in space is described which uses a two-phase working fluid to radiate waste heat. The development of new advanced materials and the large surface area per mass makes the Bubble Membrane Radiator an attractive alternative to both conventional heat pipes and liquid droplet radiators for mid to high temperature applications. A system description, a discussion of design requirements, and a mass comparison with heat pipes and liquid droplet radiators is provided.. .....

This study aimed to investigate the performance of an electromagnetic induction pump with rotating permanent magnets under different inlet pressure conditions. The tested cylindrical-type pump was placed in the test loop to test its parameters while pumping liquid sodium. The measurements of the pump characteristics were carried out at the different inlet pressure values. The inlet pressure was varied, changing initial overpressure in the loop's expansion tank from 0,1 to 1,75 bars. Inlet pressure influenced the cavitation occurrence in the pump channel, and thus, the maximal flow rate varied from 15,2 to 73 l/s. In addition to the pressure-flow rate characteristics, various data were collected during the experiments, such as drive unit power, vibration data, and acoustic signals. Analysis of these parameters showed a clear correlation between the inlet pressure and the apparent cavitation process in the pump channel. This study aimed to establish the operational limits for the electromagnetic induction pump with rotating permanent magnets. The results indicate that the pump can safely operate within the range of inlet pressure values of 0,6 bar and cavitation number values of 3,2.

The research is aimed at investigating the influence of the cavitation process on the performance of the electromagnetic induction pump with rotating permanent magnets operating in the circulation loop, where low pump inlet pressure values are maintained. Data on the inlet pressure influence on pressure-flow rate curves were obtained by an experimental approach using a disc-type pump with SmCo permanent magnets in experiments. The pump was placed in the test loop operating with liquid sodium, and measurements of the pump characteristics were made. The inlet pressure variation from 0.1 to 3.0 bar influences the maximum flow rate, thus varying it from 2 to 12 l/s.

Electricity production is a major problem for deep space exploration. The possibility of using radioisotope elements with a very long life as an energy source was investigated in the framework of an EU project “SpaceTRIPS”. For this, a two-stage system was tested, the first in which thermal energy is converted into mechanical energy by means of a thermoacoustic process, and the second where mechanical energy is converted into electrical energy by means of a magnetohydrodynamic generator (MHD). The aim of the present study is to develop an analytical model of the MHD generator. A one-dimensional model is developed and presented that allows us to evaluate the behavior of the device as regards both electromagnetic and fluid-dynamic aspects, and consequently to determine the characteristic values of efficiency and power.

This paper discusses the results of theoretical and experimental investigation of magnetohydrodynamic generator with liquid metal working body. This electric machine is used to convert mechanical energy, supplied by thermoacoustic engine, to an AC form of electrical energy. The purpose of this technology is an electricity production in deep Space, potentially suitable for long term missions far away from Sun.

Thermoacoustic-to-MHD energy conversion is a potential key technology for energy production in deep Space, due to the absence of moving mechanical parts or electrical contacts. This technology has been developed by a team of scientists from different institutes and companies from France, Italy, Latvia and Germany. Experimental results of the prototype built at the Institute of Physics, University of Latvia, are presented in this paper. It summarizes the results of several TAc-alone experimental sessions, indicating the required temperature difference and working gas mean pressure. These are the necessary parameters needed for the induction of acoustic power. The paper also discusses the operational experience gained in a preliminary water simulation for the MHD-alone experiment.

Our research is inspired by the Space Thermoacoustic Radio-Isotopic Power System Project SpaceTRIPS for deep space applications: a radio-isotopic source produces heat, a thermoacoustic engine converts it into sound. The MHD generator further converts sound into electricity. The present paper does not refer to the full project, but to an internal process inside the MHD generator. Reasonable parameterization allows analyzing the MHD generator in two steps. At first, we convert our knowledge about the magnetic field and generator geometry into an equivalent circuit with three inductances and two resistances. Afterwards a standard circuit calculation gives all working properties. For decades, the Institute of Physics has been developing conductive MHD generators acting in a DC mode. Now we have to adopt our experience in an AC mode.

The paper presents experimental results on testing a travelling wave thermoacoustic (TAc) engine using argon gas coupled with a 200 W, low-power, magnetohydrodynamic (MHD) generator using liquid sodium. The project is a terrestrial test and simulation of a radio isotopicfed electrical power supply system for deep space applications. A large range of parameters were analyzed, such as TAc generated pressure oscillation amplitude as a function of the mean pressure and temperature of the heater.

The Kilopower Project was initiated by NASA's Space Technology Mission Directorate/ Game Changing Development Program in fiscal year 2015 to demonstrate subsystem-level technology readiness of small space fission power in a relevant environment (Technology Readiness Level 5) for space science and human exploration power needs. The Kilopower Project centerpiece is the Kilowatt Reactor Using Stirling TechnologY (KRUSTY) test, which consists of the development and testing of a ground technology demonstrator of a 1-kW(electric)-class fission power system (FPS). The technologies to be developed and validated by KRUSTY are extensible to space FPSs from 1 to 10 kW(electric), which can enable modular surface FPSs for human exploration as well as higherpower future potential deep space science missions. The KRUSTY demonstration is cofunded by NASA and the U.S. Department of Energy National Nuclear Security Administration. The KRUSTY demonstration in the National Critical Experiment Research Center's Device Assembly Facility was completed in the first quarter of 2018.

A loop heat pipe (LHP) radiator trade study has been completed for radiators in the 300-550 K temperature range. Initially, a thorough component level study was completed to determine LHP operating properties over the temperature range, particularly at the high end where the Merit Number starts to fall off. Water was found to be the optimum fluid for the high end, while ammonia was a better working fluid for temperatures below 350 K. A trade study was then conducted that varied condenser O.D., temperature, panel area, fin width, fin thickness, and fin thermal conductivity. A comparison with comparable heat pipe radiators shows that the specific power of LHP radiators can be as much as 50 percent higher at temperatures above 500 K. This is offset by the fact that LHP radiator technology is much less mature.

Neutronic analysis of a conceptual heat pipe-cooled micronuclear reactor with 70 % enriched uranium nitride fuel is carried out by modeling the core and peripheral control drum movement to estimate the power distribution. The core configuration results in non-uniformities and hotspots. For the heat removal, empirical formulae have been used in the case of sodium, lithium, and potassium working fluids. The neutronic simulation was carried out by the OpenMC code. It has been found that the radial flux peaking as high as ~20 % can occur at various stages of the drum movement. The novelty of this research is the investigation of the effect of variable enrichment on the overall system multiplication, which can form the basis for optimal fuel distribution. It has been found that non-uniform fuel distribution can mitigate peaking factors, and thus reduce the hotspots. This analysis is useful for the design optimization of compact micro nuclear reactors for underwater, portable and space pr...

Liquid metal magnetohydrodynamic (LMMHD) generators can generate electricity from the movement of liquid metal in an external magnetic field, without any mechanical moving parts. They can be applied in scenarios that require a highly reliable generator, including harvesting ocean wave energy and space nuclear power generation. However, in practice, the presence of end current in LMMHD generators limits the generator efficiency to a relatively low level, which restricts their wide application. After analyzing the generating mechanism of the end current, we report herein a method to optimize the external magnetic field that cancels the electrostatic field with the motional electromotive force and suppresses the end current in LMMHD generators. We use two-dimensional numerical simulations with the proposed method to demonstrate its effectiveness, which we validate with three-dimensional numerical simulations. Both the two-and three-dimensional numerical results show that this method should suppress the end current in the LMMHD generator, thus cutting the internal joule heating nearly in half and improving the generator efficiency by 9.5%. This work provides in-depth insights into both the generating mechanism and the suppression of the end current and contributes to the development of high-efficiency LMMHD generators.

Although Lead-cooled Fast Reactor (LFR) is not a new concept, it continues to be an example of innovation in the nuclear field. Recently, there has been strong interest in liquid lead (Pb) or liquid lead-bismuth eutectic (LBE) both critical and subcritical systems in a relevant number of Countries, including studies performed in the frame of GENERATION-IV initiative. In this paper, the theoretical and computational findings for three different designs of Primary Circulation Pump (PCP) evolving liquid lead (namely the jet pump, the Archimedean pump and the blade pump) are presented with reference to the ALFRED (Advanced Lead Fast Reactor European Demonstrator) design. The pumps are first analyzed from the theoretical point of view and then modeled with a 3D CFD code. Required design performance of the pumps are approximatively around an effective head of 2 bar with a mass flow rate of 5000 kg/s. Taking into account the geometrical constraints of the reactor and the fluid dynamics characteristics of the molten lead, the maximum design velocity for molten lead fluid flow of 2 m/s may be exceeded giving rise to unacceptable erosion phenomena of the blade or rotating component of the primary pumping system. For this reason a deep investigation of non-conventional axial pumps has been performed. The results presented shows that the design of the jet pump looks like beyond the current technological feasibility while, once the mechanical challenges of the Archimedean (screw) pump and the fluid-dynamic issues of the blade pump will be addressed, both could represent viable solutions as PCP for ALFRED. Particularly, the blade pump shows the best performance in terms of pressure head generated in normal operation conditions as well as pressure drop in locked rotor conditions. Further optimizations (mainly for what the geometrical configuration is concerned) are still necessary.

Electromagnetic (EM) pumps are a major component in the safe operation of liquid metal-cooled nuclear reactors and can also be used in any other application in which a conductive fluid is being pumped through a system. During the design of an EM pump, it is useful to model its operating characteristics for pump sizing, flow capabilities, and other design checks. The EM pump analysis code known as MATRIX is a prime example of a tool that can be used for such pump modeling. This paper introduces the modernization and capability investigation efforts completed on MATRIX. An output data comparison of the modernized code is made between both the legacy code and the measured EM pump. Further improvement of MATRIX through data analysis and flow correction techniques is explained.

The following information is to be distributed for review as part of the Department of Energy's Nuclear Criticality Safety Program (NCSP) Critical Experiment Design (CED) process requirements. This Research Note is to serve as documentation for IER 299 CED phase 1 preliminary design which is the information that represents the preliminary planning, design, and analysis for the KRUSTY experimental measurements to be executed to obtain the requested data.

Specimens of T91 9%Cr martenstttc steel were exposed to molten lead at 525°C under controlled oxygen partial pressure, for durations ranging from 6 hours to one month. At low oxygen concentration, a thin chromtum oxide layer is formed; under higher concentration, the oxide layer becomes thicker and complex. Under all condttions in liquid lead, numerous porosittes appear after a few days of exposure to lead in the sub-surface regions of the samples. From the residual deflection of bent samples, the stress relaxation is much faster in liquid lead than under gaseous atmosphere. However, the tensile properties remain unchanged after one month ageing in lead. Rhum6-Influence de maintiens de longue durCe en bain de plomb liquide sur la microstructure et les propriMs mkaniques de I'acier T91. Des tchantillons d'acier a 9%Cr martensltique T91 ont subt des recutts de 6 heures a un mois en barn de plomb liquide a 525°C sous controle d'activite de l'oxygene. A faible activate d'oxygene, une fine couche d'oxyde de chrome se forme ; sous une pression plus elevee, la couche devient plus Cpaisse et complexe De nombreuses porosites apparaissent pres de la surface dam les Cchantillons apres seulement quelques jours en bain de plomb. D'apres la fleche residuehe d'echanttllons recmts en flexion, la relaxation de la contramte est nettement plus rapide en barn de plomb que sous atmosphere gazeuse. Cependant, le comportement en traction de l'acter demeure mchange apres un vtelllissement d'un mats dans le bain de plomb.

Although Lead-cooled Fast Reactor (LFR) is not a new concept, it continues to be an example of innovation in the nuclear field. Recently, there has been strong interest in liquid lead (Pb) or liquid lead-bismuth eutectic (LBE) both critical and subcritical systems in a relevant number of Countries, including studies performed in the frame of GENERATION-IV initiative. In this paper, the theoretical and computational findings for three different designs of Primary Circulation Pump (PCP) evolving liquid lead (namely the jet pump, the Archimedean pump and the blade pump) are presented with reference to the ALFRED (Advanced Lead Fast Reactor European Demonstrator) design. The pumps are first analyzed from the theoretical point of view and then modeled with a 3D CFD code. Required design performance of the pumps are approximatively around an effective head of 2 bar with a mass flow rate of 5000 kg/s. Taking into account the geometrical constraints of the reactor and the fluid dynamics characteristics of the molten lead, the maximum design velocity for molten lead fluid flow of 2 m/s may be exceeded giving rise to unacceptable erosion phenomena of the blade or rotating component of the primary pumping system. For this reason a deep investigation of non-conventional axial pumps has been performed. The results presented shows that the design of the jet pump looks like beyond the current technological feasibility while, once the mechanical challenges of the Archimedean (screw) pump and the fluid-dynamic issues of the blade pump will be addressed, both could represent viable solutions as PCP for ALFRED. Particularly, the blade pump shows the best performance in terms of pressure head generated in normal operation conditions as well as pressure drop in locked rotor conditions. Further optimizations (mainly for what the geometrical configuration is concerned) are still necessary.

This study investigated the corrosion behavior and underline mechanisms of low alloy steels with a minor addition of 0.4 wt% Cu, 0.2 wt% Ni, 0.1 wt% Sb and 0.05 wt% Co developed for a flue gas desulfurization (FGD) system. Corrosion tests were carried out in an aggressive solution of 16.9 vol% H 2 SO 4 + 0.35 vol% HCl + Bal. H 2 O at 60°C for up to 48 h. The experimental results revealed enrichment of the additional elements (Cu, Sb and Ni) in the corrosion layer, whose concentration increased with test time. As the concentrations of Cu increased, the crystallization and growth of the Cu particles (from several nm to 320 nm)) within the corrosion layer was accelerated. At the initial stage of the test, a continuous amorphous layer rich with the additional elements formed and covered the surface of the steel, which then gradually developed defects, pores and cracks, as the crystallization and growth of Cu particles with the elapse of time. The results indicated that the corrosion resistance of the low alloy steel depends on the existence form of Cu in the corrosion layer, i.e., as solute atoms or as nanoparticles strengthened the corrosion layer and increased corrosion resistance. As the coarsening of Cu particles weakened the corrosion layer and deteriorated the corrosion resistance.

In this paper, an enhanced calculation method of a heat rejection system operating on the moon is presented. This was taken into consideration in the developed calculation method and in the propagation of heat fluxes with the radiation of the removed heat. The developed method made it possible to effectively evaluate the capabilities of various refrigerants and choose the radiator parameters and the refrigerant flow regime in a less time-consuming process and with minimal deviations (<5%) compared to the previously developed two-dimensional radiator model by the authors. A comparative analysis was carried out for two refrigerants: helium and liquid ammonia. It has been established that when using liquid ammonia, there are more possibilities for varying the geometric parameters of the radiator. The use of liquid ammonia as a refrigerant made it possible to reduce the power spent on pumping the refrigerant through the radiator. Using helium, the power for pumping the refrigerant wa...

This paper presents the results of CFD and thermal-hydraulics analyses of liquid sodium heat transfer in 19 UN fuel rod hexagonal bundles with scalloped walls. These bundles are arranged in three concentric rings in the core of the Very-Small, Long-LIfe, and Modular (VSLLIM) nuclear reactor. The rods are arranged in a triangular lattice with P/d = 1.2 and the scalloped walls ensure same flow area per rod in the bundles, and hence the radial uniformly of the liquid sodium flow for enhanced thermal performance. The analyses investigate the effects of the reactor power, P RX (1.0, 5.0, and 10 MW th) and the fission power distributions in the UN fuel on the radial and axial distributions of the fuel temperatures as well as the axial and radial distributions of the liquid sodium temperature and flow velocity in the hottest bundle in the reactor core. The analyses also calculate the bundle friction factor, f b , and the local Nusselt number, Nu, of liquid sodium along the bundle. The effect of the numerical mesh refinement on the results convergence is also investigated. The obtained values of f b and the fully developed Nusselt at different reactor thermal powers are within ±8% and +0.5 of reported correlations based on extensive CFD and experimental databases. At P RX = 10 MW th , the maximum UN fuel temperature in the hottest bundle in the VSLLIM reactor core is quite low ($811 K), which ensures almost full retention of fission products in the UN fuel and minimal fuel swelling. The corresponding average temperature of the liquid sodium exiting the reactor core is 752 K. This temperature is not only suitable for attaining high plant thermal efficiency ($35-38%), but also compatible with the HT-9 steel cladding and core structure for the long operation lives of the VSLLIM reactor.

h i g h l i g h t s Developed low enrichment and natural circulation cooled SLIMM-1.2 SMR for generating 10-100 MW th. Neutronics analyses estimate operation life and temperature reactivity feedback. At 100 MW th , SLIMM-1.2 operates for 6.3 FPY without refueling. SLIMM-1.2 has relatively low power peaking and maximum UN fuel temperature < 1400 K.

Pulsating heat pipe's (PHP) are one of the alternatives to conventional heat transfer technologies. First part of this paper, titled: thermohydrodynamic behavior of methanol charged closed loop pulsating heat pipe has given information about thermo-hydrodynamic operational characteristics such as; bubble nucleation and collapse, bubble agglomeration and pumping action, flow regime changes, pressure/temperature perturbations, dynamic instabilities, meta-stable non-equilibrium conditions etc. in the PHP. Present paper, which is an extension of the previous work, it presents some more thermal results to highlight the effect of; thermo-physical properties of working fluid, filling ratio and number of turns on thermal performance of PHP. Three different PHP loop has been made from six, four and two parallel glass tubes (i.e. three turns, two turns and one turn at evaporator section) forming adiabatic section, interconnected alternately by copper U tubes, having internal and external diameter 2 mm and 3.06 mm respectively. The length of evaporator, condenser and adiabatic section are 42 mm, 50 mm and 170 mm respectively. The experimentation conducted for different working fluids (water, ethanol, methanol and acetone), different filling ratio's (30%FR, 50%FR and 70%FR) and different number of turns (one, two and three turns). The motto of present research is to understand the thermal performance in terms of thermal resistance of PHP in details. The result shows that, thermal resistance for all working fluid PHP's rapidly decreases with increasing heating power up to 32W. For low heating power, working fluid (acetone) which has lower boiling temperature is best, but it cannot give the service for higher heating power. Two turn PHP loop with methanol 50% volumetric filling ratio at more than 32W heating power with one directional flow circulation is the optimum operating condition of present research.

A transient analysis has been carried out in detail using the finite difference method for the roll heat pipe wish is firstly studied by Jalilvand [1] in photocopy machines. The objective of this study is to better understand this type of heat pipes for further heat recovery applications or other designs processes that are essentially transient. The numerical results shows that the roll heat pipe perform better than the annular heat pipe of same dimension and the condenser region is essentially controlled by the heat Input and the convective heat transfer coefficient. .

Mild or low-carbon steel has an increasing utilization and is widely used for building construction, machinery parts, and pipelines, because it can be machined easily and has enhanced weldability as well as a low price. In any case, the corrosion resistance of mild steel under the conditions in industrial applications or in atmosphere is a thoughtful concern. This study inquires into the application of 2-mecraptobenzothiazole (MBT) and Na2HPO4 as corrosion inhibitors for the protection of API 5L X42 pipeline steel in 3.5 wt % NaCl as well as in water from the Athens city supply system. The electrochemical/morphological characterizations of the aforementioned mild steel proved that the corrosion protection mechanisms can be assigned to the protective layers created onto the metal surface because of the presence of the inhibitors, which prevent chloride’s penetration. The synergistic effect of the MBT and Na2HPO4 corrosion inhibition behavior, in a molar ratio of 1:1, revealed that th...

The present paper is conducted to develop a new structure of an electromagnetic pump capable of controlling the magnetic field in a rectangular channel. Common electromagnetic pumps do not create uniform velocity profiles in the cross-section of the channel. In these pumps, an M-shape profile is created since the fluid velocity in the vicinity of the walls is higher than that in its center. Herein, the arbitrary velocity profiles in the electromagnetic pump are generated by introducing an arrayed structure of the coils in the electromagnetic pump and implementing 3D numerical simulation in the finite element software COMSOL. The dimensions of the rectangular channel are 5.5 × 150 mm2. Moreover, the magnetic field is provided using a core with an arrayed structure made of low-carbon iron, as well as five couples of coils. 20% NaoH solution is utilized as the fluid (conductivity: 40 S/m). The arrayed pump is fabricated and experimentally created an arbitrary velocity profile. The pres...

The Early Flight Fission-Test Facility (EFF-TF) was established by the Marshall Space Flight Center to provide a capability for performing hardware-directed activities to support multiple in-space nuclear reactor concepts by using a non-nuclear test methodology. [1,2] This includes fabrication and testing at both the module/component level and near prototypic reactor configurations. The EFF-TF is currently supporting an effort to develop an affordable fission surface power (AFSP) system that could be deployed on the Lunar surface. [3] The AFSP system is presently based on a pumped liquid metal-cooled (Sodium-Potassium eutectic, NaK-78) reactor design. [4,5] This design was derived from the only fission system that the United States has deployed for space operation, the Systems for Nuclear Auxiliary Power (SNAP) 10A reactor, which was launched in 1965. [6]

The results of assessing five-year corrosion of low-carbon and conventional weathering steels exposed to the Panamanian tropical atmosphere is presented. Two different test sites, one in Panama City: 5 km from the shoreline of the Pacific Ocean, and another in the marine environment of Fort Sherman, Caribbean coast of Panama; namely, Fort Sherman Coastal site: 100 m from coastline. The corrosion products, formed in the skyward and earthward faces in the studied tropical environment, were mainly identified using room temperature and low temperature (15 K) Mössbauer spectroscopy, and ATR-FTIR. In all samples, lepidocrocite (γ-FeOOH) and goethite (α-FeOOH) were the main constituents. Some maghemite (γ-Fe 2 O 3), was also identified in Tocumen by Mössbauer spectroscopy and traces of feroxyhyte (δ-FeOOH) using ATR-FTIR. The corrosion rate values obtained are discussed in light of the atmospheric exposure conditions and atmospheric pollutants.

One conventional and three Ni-advanced weathering steels have been exposed for one year in two marine atmospheres of moderate aggressivity (30 and 75 mg Cl À /m 2 d). The rusts generated have been analysed by polarised light optical microscopy, SEM, XRD, Raman spectroscopy and Mössbauer spectroscopy. The presence of high nickel (1-3% weight) contents in the steel composition leads to higher corrosion resistance in moderate marine atmospheres. The presence of nickel in the weathering steel also raises the proportion of nanophasic (superparamagnetic) goethite in the inner rust layer.

Liquid /Fluid Sodium is very risky in nature[1]. It gets ignited thusly when introduced to air or water. They recall repressions for smothering administrators. Social wellbeing and affirmation are basic. In many impelled organizations and present-day nuclear force stations, liquid sodium utilized as a basic coolant. This technique offers challenges to nuclear powerhouses. The fire remains an overall supporter of intensity plants. Research on capable fire ID and cautioning structures has become a fervently discussed issue in ventures. In many force stations and manufacturing plants, PLC or microcontroller-based controllers are utilized. Most of the customary frameworks will be rule-based. Now and again, they give counterfeit cautions. There is a need to naturally recognize outpouring and fire utilizing most recent advances like man-made reasoning. These days, most of the enterprises are fixed with CCTV or other observing frameworks. Our point is to utilize Video and Traditional way t...

Although Lead-cooled Fast Reactor (LFR) is not a new concept, it continues to be an example of innovation in the nuclear field. Recently, there has been strong interest in liquid lead (Pb) or liquid lead-bismuth eutectic (LBE) both critical and subcritical systems in a relevant number of Countries, including studies performed in the frame of GENERATION-IV initiative. In this paper, the theoretical and computational findings for three different designs of Primary Circulation Pump (PCP) evolving liquid lead (namely the jet pump, the Archimedean pump and the blade pump) are presented with reference to the ALFRED (Advanced Lead Fast Reactor European Demonstrator) design. The pumps are first analyzed from the theoretical point of view and then modeled with a 3D CFD code. Required design performance of the pumps are approximatively around an effective head of 2 bar with a mass flow rate of 5000 kg/s. Taking into account the geometrical constraints of the reactor and the fluid dynamics characteristics of the molten lead, the maximum design velocity for molten lead fluid flow of 2 m/s may be exceeded giving rise to unacceptable erosion phenomena of the blade or rotating component of the primary pumping system. For this reason a deep investigation of non-conventional axial pumps has been performed. The results presented shows that the design of the jet pump looks like beyond the current technological feasibility while, once the mechanical challenges of the Archimedean (screw) pump and the fluid-dynamic issues of the blade pump will be addressed, both could represent viable solutions as PCP for ALFRED. Particularly, the blade pump shows the best performance in terms of pressure head generated in normal operation conditions as well as pressure drop in locked rotor conditions. Further optimizations (mainly for what the geometrical configuration is concerned) are still necessary.

Liquid alloy systems have a high degree of thermal conductivity, far superior to ordinary nonmetallic liquids and inherent high densities and electrical conductivities. This results in the use of these materials for specific heat conducting and dissipation applications for the nuclear and space sectors. Uniquely, they can be used to conduct heat and electricity between nonmetallic and metallic surfaces. The motion of liquid metals in strong magnetic fields generally induces electric currents, which, while interacting with the magnetic field, produce electromagnetic forces. Electromagnetic pumps exploit the fact that liquid metals are conducting fluids capable of carrying currents, which is a source of electromagnetic fields useful for pumping and diagnostics. The coupling between the electromagnetics and thermo-fluid mechanical phenomena and the determination of its geometry and electrical configuration, gives rise to complex engineering magnetohydrodynamics problems. The development of tools to model, characterize, design, and build liquid metal thermomagnetic systems for space, nuclear, and industrial applications are of primordial importance and represent a cross-cutting technology that can provide unique design and development capabilities as well as a better understanding of the physics behind the magneto-hydrodynamics of liquid metals. First studies for the development of computational tools for the design of liquid metal electromagnetic pumps are discussed.

Liquid /Fluid Sodium is very risky in nature[1]. It gets ignited thusly when introduced to air or water. They recall repressions for smothering administrators. Social wellbeing and affirmation are basic. In many impelled organizations and present-day nuclear force stations, liquid sodium utilized as a basic coolant. This technique offers challenges to nuclear powerhouses. The fire remains an overall supporter of intensity plants. Research on capable fire ID and cautioning structures has become a fervently discussed issue in ventures. In many force stations and manufacturing plants, PLC or microcontroller-based controllers are utilized. Most of the customary frameworks will be rule-based. Now and again, they give counterfeit cautions. There is a need to naturally recognize outpouring and fire utilizing most recent advances like man-made reasoning. These days, most of the enterprises are fixed with CCTV or other observing frameworks. Our point is to utilize Video and Traditional way t...