Temperature Liquid Sodium Research Articles

Na–K Co‐deposition in Liquid‐Alloy Batteries Revealed by Operando Visualization

Despite the great prospects of alkali metal batteries, safety concerns associated with dendrite growth still limit their commercial applications. An attractive alternative is to use the room temperature liquid sodium–potassium alloy as the anode, which inherently prevents dendrite growth. Currently, Na–K alloy anodes allow only Na+ or K+ to be cycled, depending on the choice of electrolyte and ion selectivity of the cathode, which results in reduced energy density of the battery. Herein, the possibility of concurrent use of both Na+ and K+ ions in Na–K alloy anodes is explored, and the working mechanism by operando optical microscopy is investigated. It is found that the type of deposited metal is dictated by both salt and solvent in electrolyte. Impressively, Na–K co‐deposition is observed in KFSI‐DME electrolyte for the first time, which strongly influences the dendrite morphology and evolution. Furthermore, the current density also has a great impact on the deposition pattern, which allows dendrite‐free Na/K deposition on the liquid‐alloy anode. These findings enrich our understanding of the intricate electrochemical behaviors of Na–K binary electroactive alloy systems and offer guidance for the sufficient use of Na and K while avoiding dendrite formation in such liquid‐alloy batteries.

Anomaly Detection in Liquid Sodium Cold Trap Operation with Multisensory Data Fusion Using Long Short-Term Memory Autoencoder

Sodium-cooled fast reactors (SFR), which use high temperature fluid near ambient pressure as coolant, are one of the most promising types of GEN IV reactors. One of the unique challenges of SFR operation is purification of high temperature liquid sodium with a cold trap to prevent corrosion and obstructing small orifices. We have developed a deep learning long short-term memory (LSTM) autoencoder for continuous monitoring of a cold trap and detection of operational anomaly. Transient data were obtained from the Mechanisms Engineering Test Loop (METL) liquid sodium facility at Argonne National Laboratory. The cold trap purification at METL is monitored with 31 variables, which are sensors measuring fluid temperatures, pressures and flow rates, and controller signals. Loss-of-coolant type anomaly in the cold trap operation was generated by temporarily choking one of the blowers, which resulted in temperature and flow rate spikes. The input layer of the autoencoder consisted of all the variables involved in monitoring the cold trap. The LSTM autoencoder was trained on the data corresponding to cold trap startup and normal operation regime, with the loss function calculated as the mean absolute error (MAE). The loss during training was determined to follow log-normal density distribution. During monitoring, we investigated a performance of the LSTM autoencoder for different loss threshold values, set at a progressively increasing number of standard deviations from the mean. The anomaly signal in the data was gradually attenuated, while preserving the noise of the original time series, so that the signal-to-noise ratio (SNR) averaged across all sensors decreased below unity. Results demonstrate detection of anomalies with sensor-averaged SNR < 1.

An insight into the flow field characteristics of the high temperature liquid Sodium (Na) with cavitation effects in the 600 MW fast reactor system

The paper explores the flow field characteristics of liquid Sodium pump, the flow field calculation model is established. The head and efficiency curves of sodium pump obtained by simulation are compared with the test data to verify the accuracy of the model. Flow characteristics inside the impeller, guide vane and the volute are investigated and summarized. The pressure distribution and velocity distribution characteristics of the steady flow field and the pressure fluctuation and fluid force characteristics of the unsteady flow field are further analyzed, which provides the basis for the calculation of flow induced vibration and sound field. The dynamic processes of Sodium cavitation effects are stimulated and studied systematically. The causes of fluid excited vibrations in Sodium pump are preliminarily revealed. Researches have remarkable guiding significances for the analysis of flow characteristics of Sodium pump system of the new generation 600 MW nuclear main pump system.

Utilization of human urine and waste aluminum for generation of hydrogen

In the present work, the in situ/on-demand hydrogen generation from the human urine and waste aluminum metal wire has been experimentally explored in the presence of non-reacting room temperature liquid metal gallium (Ga) and sodium hydroxide (NaOH). The effect of Ga on the reaction was investigated at various additions in the range 80–99% (by weight of total metal). Every proportion of added Ga was studied at two concentrations of aq. NaOH viz. 1.0 N and 1.5 N and three various temperatures i.e. 50, 60, and 70 °C. The maximum intensification of 20-fold in the hydrogen generation rate was observed at 1.0 N aq. NaOH at 50 °C. The appreciable hydrogen generation rate up to 26 mL/min/0.1 g Al was obtained. The effect of Ga was found to be prominent at lower reaction temperatures and concentrations of aq. NaOH. Ga added in the reaction was completely recovered and reused in the reaction.

A study on sodium - the fast breeder reactor coolant

Sodium, the second alkali metal in the first group of periodic table is highly chemically reactive. Sodium is widely used in pharmaceutical industries to manufacture lifesaving medicines. Liquid sodium is an excellent reducing agent and heat transport medium, which makes it an important industrial material. The application of this element in liquid form at high temperature as a coolant in fast breeder nuclear reactors necessitated development of sodium technology. Physical, chemical and nuclear properties of sodium led to the choice of sodium as the universally accepted fast breeder reactor (FBR) coolant. The manufacturing of sodium is by electrolysis process. The design and manufacturing requirements of high temperature liquid sodium system components are successfully addressed. Special type of sensors needed for high temperature liquid sodium system are specifically designed and developed. Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam is involved in the development of sodium technology in India. Sodium technology is matured to an extent and around twenty FBRs with sodium as the coolant were constructed, commissioned and successfully operated all over the world. Five sodium cooled fast reactors are currently in operation including fast breeder test reactor (FBTR) in India. Prototype fast breeder reactor (PFBR) is in the advanced stage of commissioning at Kalpakkam. This review paper explains the choice of sodium as FBR coolant and gives highlights on the research and development took place in sodium technology all over the world especially in India with an aim to give an exposure to this technology to the academic community.

Mechanical behavior of SiC/SiC composites after exposure in high temperature liquid sodium for Sodium Fast Reactors applications

SiC/SiC composites have aroused interest for various nuclear applications. For example, the use of SiC/SiC components in Sodium-cooled Fast Reactors in replacement of steel wrapper tubes should improve the safety. However, the chemical compatibility between the liquid sodium and SiC or SiC/SiC composites and its effect on their mechanical properties remain unknown. Corrosion tests were conducted on CVD SiC and both undamaged and pre-damaged SiC/SiC in liquid sodium at 823 K up to 2000 h in two different sodium batches, a purified and an oxygen-rich. No strong corrosion of the CVD SiC and no degradation of the mechanical properties of SiC/SiC composites were observed in both conditions, even with mechanical pre-damaging prior to immersion. A strong increase in ultimate tensile strength was highlighted after exposure, only for the undamaged samples. This phenomenon is attributed to the healing by liquid sodium of the microcracks generated during the manufacturing process.

Analysis of the flow noises of the nuclear main pump caused by the high temperature liquid Sodium in the two-circuit main loop liquid Sodium pump system

The paper investigates the flow noises caused by the high temperature liquid Sodium in the nuclear main pump system. Three-dimensional unsteady CFD coupled sound field methods are exploited. Spectrum characteristics of sound source load are obtained. Directional sound pressure level distribution based on sound source load of rotor blades and guide vanes are presented and discussed. Distribution of sound pressure level of inlet and outlet pipes along the flow direction are also further discussed. Results indicate that with the increase of blade passing frequency, the amplitude of sound pressure level decreases. Response of sound field mainly depends on the load characteristics of rotor blades. Research results have remarkable significances for the analysis of flow noises in liquid Sodium pump systems.

Corrosion behavior of surface treated steel in liquid sodium negative electrode of liquid metal battery

While liquid metal batteries are attractive options for grid-scale energy storage applications as they have flexible siting capacities and small footprints, the compatibility between structural materials such as current collectors and negative electrode such as sodium is one of major issues for liquid metal batteries. Non-metallic elements such as carbon, oxygen, and nitrogen in the liquid sodium influence the material behaviors of the cell construction materials in the battery system. In this study, the compatibility of structural materials with sodium is investigated in high temperature liquid sodium, and electrochemical impedance spectroscopy (EIS) is used to monitor in-situ the corrosion behavior at the surface of materials in sodium. Chemical vapor deposition (CVD) coatings of SiC and Si3N4 are applied as protective barriers against dissolution and corrosion on the steel surface. The results show that CVD coating of Si compounds can delay corrosion of steel in high temperature liquid sodium comparing to the result of as-received specimens, while SiC coating is more durable than Si3N4 coating in high temperature liquid sodium.

Experimental evaluation of permanent magnet probe flowmeter measuring high temperature liquid sodium flow in the ITSL

The Instrument Test Sodium Loop (ITSL) installed at Korea Atomic Energy Research Institute (KAERI) is a medium-size experimental facility dedicated to obtaining relevant experimental data of liquid sodium flow characteristics under various thermal hydraulic conditions and sodium purification. The ITSL has been utilized to perform thermal flow measurement of the liquid sodium and to calibrate a Permanent Magnet Probe Flowmeter (PMPF). The primary objective of this study is to obtain liquid sodium flow rate given a wide temperature range using the PMPF. Non-stationary method was adopted for the calibration of the probe given the liquid sodium temperature range of 150–415°C. A relationship between the measured voltage signal and flow rate was obtained successfully. It is observed that the calibration experiments result in excellent linear relationships between measured voltage and volumetric flow rate at various temperature conditions. Also a computational analysis using FlowMaster, is employed to facilitate the calibration process by predicting the liquid sodium flow rate. Finally the effect of the fluid temperature on thermal flow measurements is discussed in light of the obtained experimental data.

Cr基被覆材料の高温Na中における摩擦特性

Cr基被覆材料の高温Na中における摩擦特性

Experimental study of self-welding of materials in high temperature liquid sodium

To study self-welding of materials in high temperature liquid sodium, an experimental set-up consisting of a sodium-circulating loop, a test vessel, a loading mechanism for material specimens and instrumentation were designed, installed and operated at IGCAR, Kalpakkam. Combinations of austenitic stainless steel, hard chrome plating and Stellite-6 with the surface finish of the contact surfaces typical of that of components in fast breeder reactors were exposed to liquid sodium at 530 °C under load intensities of 10 and 40 MPa for 500 and 1000 h. The paper discusses the experimental set-up installed and the results of self-welding of these material combinations. The role of surface finish on self-welding tendency is also briefly discussed.

Carbon potential and carbide equilibrium in 18/8 austenitic steels

Austenitic stainless steels are in contact with high temperature liquid sodium in a fast reactor. In order to understand the carbon transport occurring between various regions of these materials through liquid sodium, an accurate knowledge of the carbon activity-concentration relationship in the austenitic steels is essential. A new method involving equilibration of the steel sample with liquid sodium coupled with the measurement of carbon activity in sodium, employing an electrochemical carbon meter, is reported for the measurement of the carbon potential of the steel at different carbon concentrations in the temperature range of 860–960 K. The results obtained are discussed and a new expression is proposed relating carbon activity with the composition of steel. The thermodynamics of carbide equilibrium in the steel are studied by isolating and characterising the carbide phase. These data have been analysed using a regular solution model for the carbide phase, M23C6 and based on this the observed composition of M23C6 as well as the variation of the carbon potential of steel with temperature have been explained.

Time dependent crack growth of type 304 stainless steel in elevated temperature sodium

The crack growth characteristics, under constant load and in elevated temperature liquid sodium, were studied for Type 304 stainless steel through using linear elastic fracture mechanics. The crack growth rates are represented by the Arrhenius equation. Furthermore the crack growth rates in sodium, at 873 K and oxygen concentrations of 0.71 and 15 ppm, were examined. The crack growth rates seem to increase in accordance with increased oxygen concentration, however the difference is slight. Scanning electron microscope observations were made of corrosion products on the fracture surface at 15 ppm oxygen. However, at 0.71 ppm the corrosion products could not be observed. So the mechanism of crack growth seems to be related to impurities in sodium.

An Ultrasonic Viewing System in Liquid Sodium

This under sodium viewing system has been developed for identifying fuel subassemblies placed in optically opaque high temperature liquid sodium. This system has a transducer for emitting and receiving ultrasonic waves in liquid sodium, scanning mechanism under liquid sodium and an image display unit. The evaluation test results are; 1) This system has been proved to operate satisfactorily under 300°C sodium for 15 days. 2) These images, obtained from the experiments in liquid sodium, were as celar as those in room temperature water.

Investigatiom of deposition and wear problems with hardfaced coatings for high temperature liquid metal service

We have examined hardfaced coatings on two valves that were designed for use in high temperature liquid sodium environments. The valve bodies were type 304 stainless steel and were hardfaced with AWSRCoCr-A (cobalt-base material) using the gas tungsten-arc process. One valve was a cold leg trap valve that was removed from the Sodium Component Test Installation at the Liquid Metal Engineering Center. Owing to system redesign this valve was removed from sodium service after 40 000 h at temperatures up to 427°C (800°F). It had experienced some sticking but this was not of significant consequence. The microstructure of RCoCr-A consists of an austenite matrix and a carbide and eutectic carbide interdendritic structure from which the material gains its wear resistance. Evaluation revealed evidence of erosion/corrosion of the hard interdendritic material, thus leaving a wear surface of softer matrix material. As a result, some galling (self-wedding) of the wear surfaces apparently occured. The other valve was a hot leg isolation valve intended for use in the Fast Flux Test Facility. This valve was rejected owing to hot cracking during deposition of the hardfacing material (coating) and was not put into operation. The hardfaced surface was inspected for liquid penetration and was sectioned for evaluation by metallographic examination, scanning electron microscopy and microprobe analysis. It was concluded that hot cracking occured in the base metal, due to liquation of grain boundaries in the weld heat-affected zone, and was followed by crack propagation through the hardfaced deposit.

Ball Bearings for High Temperature Liquid Sodium

A project has been conducted in support of the liquid metal cooled fast breeder nuclear reactor development, in which ball bearings have been designed, manufactured, and tested specifically for a typical reactor application involving operation in high temperature sodium. A powder-processed tool steel was selected for rings and balls, and cages were manufactured from various candidate materials. Test bearings were made according to 7306 size (30 mm bore) envelope dimensions and tested under pure thrust loads up to 500 lbs, and speeds up to 1,000 rpm. A bearing life of 4 million shaft revolutions (67 hrs) was achieved in 600 F liquid sodium with an oxide concentration of 51 to 69 parts per million for the major part of the test. Excessive torque (greater than 30 pound inches), bearing noise (hash) and/or incipient binding constituted failure criteria. Wear of the balls and rings was identified as the principal operative failure mechanism determined by correlating operating performance and post-test microsco...

An Incore Detector for Measuring Power and Breeding Distributions in Power Breeders

For optimum operation of fast breeder reactors, knowledge of the incore power and breeding distributions is desirable. Because of the high temperature liquid sodium environment in the breeders, an activation method rather than a technique involving ion chambers seems to be the most appropriate experimental technique at present. An activation system has been worked out in which 1/16" BeO balls containing oxides of 235U and 238U are inserted into the reactor for activation and withdrawn to be counted in a Ge(Li) counter. Measurements of the activated fission and 239Np gamma-rays yield the desired information. Parameters and procedures are obtained based on a specific fast Demonstration Breeder design. However, only slight modification would be required for the application to other breeders.

The form of oxygen in the liquid alkali metals

Hall measurements are used with a free-electron interpretation to determine the change in the number of electrons in the conduction band of liquid cesium on the addition of oxygen. It is shown that the measurements agree closely with models in which two electrons are removed from the conduction band for each oxygen atom added, and nuclear magnetic resonance measurements are used to decide between the two main models which present themselves. The conclusion is that oxygen in liquid cesium exists in the form of O −− ions. For high temperature liquid sodium it is suggested that, until further information is obtained, the assumption that oxygen in solution is present as O −− ions should at least be given equal weight with the previously dominant assumption that the oxygen is present in Na 2O molecules.