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At least 1,171 records · Page 65

Alternative Liquid DSA Containers for Sludge Slurry Storage in the SRNL Shielded Cells

A pending revision of the Documented Safety Analysis (DSA) for the Savannah River National Laboratory (SRNL) defines “DSA containers” for liquid sludge slurries as containers not susceptible to a flashing spray release in a fire and requires that a list of DSA containers be maintained. High Level Waste (HLW) samples are typically received from the Savannah River Site (SRS) tank farm after retrieval from the storage tanks. Glass bottles are preferred for long-term storage of radioactive liquid sludge slurry samples but are not on the DSA container list. An evaluation has been conducted to identify vessel lids for the glass bottles that would vent prior to pressurization and liquid superheating in a fire event. Low melting Field’s Metal eutectic alloy with a melting point of 62 °C has been identified as a preferred material of construction for vessel lids for this application because the material is resistant to puncture and is expected to have good chemical compatibility and radiation stability in the shielded cells environment. A test vessel was designed to evaluate the alloy and confirm that it would melt before the water in the vessel reaches the boiling point. The tests confirmed: 1) that the reported melting point of the alloy was accurate, 2) that a top fashioned from this material will melt creating an open atmosphere in the vessel headspace prior to sample boiling under moderate and fast heating rates, and 3) that nonuniform heating of the bottle from the bottom also results in melting of the alloy prior to boiling. Based on the results, neither an engulfing fire with standing or toppled bottles or a fire producing localized heat at the vessel bottom would result in flashing spray conditions.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Evaluation of the Generation-2 Dechlorination Apparatus for Treating Salt Wastes

This document satisfies the requirements for two milestones, i.e., M2FT-21PN030103021 and M3FT-21PN030103026, which are described in detail below. Also, details for the work package at the Pacific Northwest National Laboratory (PNNL) are provided below. The goal of this milestone was to demonstrate the generation-2 dechlorination apparatus (G2DA) for removing Cl from chloride-based electrochemical salt simulants. The two salts chosen for this initial study were KCl to simulate a component from the eutectic salt (LiCl is harder to detect with analytical instruments) and CsCl to simulate a fission product chloride that might be present in these types of waste streams. The overall scope of this work included receiving, installing, and testing the G2DA. This new system was designed to address several shortcomings identified with the generation-1 apparatus (G1DA), which are described in detail within this document. The G2DA was designed to address all of these shortcomings. The studies presented in here show that the G2DA worked as intended and will help provide scaled-up batches for additional testing at Argonne National Laboratory.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Precision of Property Measurements with Reference Molten Salts

Thermochemical and thermophysical properties of reference molten salt systems are being measured to establish the precisions achievable with current state-of-the-art methods including repeatability within a laboratory and reproducibility between laboratories using the same and different methods. Several laboratories across the United States are analyzing salt samples from single source batches of two salts to provide independent measurements of property values and the precisions of different measurement techniques in an interlaboratory study referred to as the Interlaboratory Salt Study (ISS). The compositions of the two salts produced for the study were reported to be eutectic LiF-NaF-KF (46.5-11.5-42 mol %) and NaCl-KCl (50-50 mol %). These salts are referred to herein as ISS FLiNaK and ISS NaCl-KCl. Thermochemical properties being measured at Argonne include thermal transitions and heat capacity by differential scanning calorimetry. Thermophysical properties being measured at Argonne include liquid density and surface tension by using a buoyancy densitometer and thermal diffusivity by using a laser flash analyzer. Thermal conductivity is calculated from measured thermal diffusivity, density and heat capacity values. The results of property measurements made at Argonne using these inter-laboratory salt study salts are presented here.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Study of Ionic Mass Transport in Non-Conventional Electrolytes for Energy Storage and Carbon Capture Applications

In the field of energy storage, electrolytes are the materials or liquids used to transport ions or redox active chemicals to facilitate an electrochemical process. Conventional electrolytes are the most common form of electrolyte used and consist of salts dissolved in a liquid solvent medium. While conventional electrolytes are generally inexpensive and work well with lithium-ion batteries, they have many shortfalls however, such as corrosion of the cell, flammability, toxicity, price, and incompatibility with other metals. This project investigates the fundamental properties in nonconventional electrolyte systems with an initial focus on eutectics being made. Using electrochemical methods ( Cyclic Voltammetry (CV), Impedance, Conductance, etc.), we are studying the study of electrolyte systems containing ions used for thermal, chemical, or electrochemical energy storage such as Li + , Mg 2+ , Na + , K + , Al 3+ , CO 3 2- , Cl - , and O 2- . This research looks at how ion mobility effects the electrochemical characteristics and properties in green energy applications.

25 ENERGY STORAGE↗

Modeling Molten Salt Spreading and Heat Transfer using MELTSPREAD – An Uncertainty Analysis

This report summarizes spreading and heat transfer results for molten salt pouring onto a flat stainless steel substrate that were calculated using MELTSPREAD to gain insight into bulk salt behavior during a molten salt spill accident. MELTSPREAD was developed at Argonne to model the one-dimensional flow and freezing behavior of molten corium and is being applied to model molten salts for the first time as part of this work. An uncertainty analysis of thermophysical properties and spill conditions was performed using MELTSPREAD to determine which properties and conditions have the greatest impact on model outcome. The model was run with and without the inclusion of decay heat. Eutectic FLiNaK was used as the salt composition because it is well-characterized and appropriate for model development. Small salt volumes were used for the initial model runs described in this report so that the model results can be compared to the results from ongoing experiments on molten salt spreading and heat transfer currently being conducted at Argonne at a benchtop scale. The spreading of a small volume of FLiNaK (50 mL) was found to be limited by the balance between the molten salt surface tension and gravity and not by freezing for the pour conditions and assumed mechanisms of heat transfer in the model. Heat transfer from the salt was highly inefficient to due to its low thermal conductivity, high heat capacity, and high heat of fusion and varying these properties had no effect on the spreading behavior. Changing the viscosity and density of the salt slightly affected the spreading behavior. Setting the salt surface tension to approximately zero to simulate the salt wetting the substrate had the greatest effect on the spreading behavior and this increased both the spreading velocity and overall spreading area. Including decay heat in the model had a significant effect on the long-term cooling behavior of the salt but had no effect on the overall spreading behavior. Future effort should involve modeling a larger volume of molten salt to represent a reactor case spill scenario because the spreading behavior of large volumes of salt may differ from the small volumes that were the focus of this document.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Testing to Evaluate Processes Expected to Occur during MSR Salt Spill Accidents

Obtaining a license for a new nuclear reactor requires the identification and assessment of the potential consequences of specified accident scenarios, which are achieved using accident progression models. Those models need to be parameterized and validated using experimental data, but existing experimental data addressing processes relevant to molten salt reactor accidents are sparse. Specifically, experimental data that quantify the sensitives of important processes to the initial conditions of the spill, the ambient environment, and the containment features are needed to parameterize individual process models. Integrated experiments that simulate accident scenarios are also needed to provide data for model validation, but these experiments will require the use of proven methods to quantify the processes under evaluation. The overarching objectives of this work are to develop the methods for simulating the targeted processes, to determine the effectiveness of the methods in producing the data required for model development, to generate data that can be used to parameterize individual process models, and to provide key insights into the behavior of spilled molten salt that should be considered in models. Experimental methods were designed to quantify aspects of individual processes expected to occur during or after a molten salt spill accident that will affect the fate of spilled molten salt and the radionuclides within. These processes include 1) molten salt spreading and heat transfer, 2) molten salt flowing and freezing in tubing, 3) stainless steel corrosion kinetics in molten salt, and 4) molten salt splashing and aerosol generation. The initial tests described in this report were conducted using eutectic FLiNaK to demonstrate the test methods, the data that are generated, and the analyses of the data to derive values needed for modeling. The primary variables that were tested include initial salt temperature and the presence of volatile surrogate fission products (e.g., cesium and iodine). The developed methods are shown to be effective in quantifying the desired processes and can be applied to study more complex salt compositions of interest to molten salt reactor developers, a wide range of environmental conditions of interest to modelers, and additional variables relevant to salt spill accidents. The developed methods and insights gained from laboratory tests can also be incorporated in future large-scale integrated tests used to simulate molten salt spill accidents.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Niowave Ancillary Systems – FY21: In Partial Fulfillment of the Deliverable Requirement for Niowave Ancillary Systems Support by LANL

Niowave Inc. produces medical radioisotopes within the US. Lead-bismuth eutectic (LBE) is irradiated using an electron beam to produce neutrons that are used in the production of Molybdenum-99 (Mo-99). The medical community relies on a steady supply of Mo-99 which is primarily used in medical diagnostic imaging. The irradiation of LBE results in high temperatures within the molten metal, this work focusses on the design of ancillary systems associated with the liquid metal system. The LBE is initially at a temperature of 200°C and flows over a steel plate to create a waterfall. The electron beam is then aimed at the waterfall to generate neutrons. The peak temperatures of the LBE post irradiation depend on the beam energy of the LINAC. For a 15 MeV and 20 kW beam, the temperatures can range between 300°C and 350°C. The LBE is cycled through the system to create a closed loop that requires the post-irradiation LBE to be cooled back to 200°C. This work focuses on the heat exchanger and condenser system responsible for the cooling of the post-irradiation LBE.

36 MATERIALS SCIENCE↗

Thermal Property Characterization of Molten Salt Reactor–Relevant Salts

The thermochemical and thermophysical properties of molten salt systems are necessary input for the design, licensing, and deployment of molten salt reactor concepts. The thermochemical and thermophysical property measurement capabilities being used and developed at Oak Ridge National Laboratory (ORNL) include liquid density, volumetric thermal expansion, viscosity, vapor pressure, phase behavior, and heat capacity and thermal conductivity measurement capabilities. Properties of eutectic LiF-NaF-KF (FLiNaK) and NaCl-KCl are being measured to validate the measurement techniques to be used to provide data to reactor developers and to better quantify the uncertainty of measurements. This report summarizes the status of thermal conductivity, viscosity, specific heat capacity, and density. A method for property estimation using Redlich Kister expansion is also described. This technique will be used to help validate measured properties and to guide future experiments by targeting mixtures or components for which data are uncertain or lacking.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Thermochemical Property Measurements of FLiNaK and FLiBe in FY 2020

The technical bases and methods developed at Argonne to measure thermochemical properties of molten salt mixtures are summarized and results provided to show the precision achieved. These methods include measurements of phase transition temperatures and heat capacity at temperatures to approximately 700°C for eutectic mixture of 46.5-11.5-42.0 mol% LiF-NaF-KF (FLiNaK) and 67-33 mol% LiF-BeF 2 (FLiBe). Details of procedures, calibrations and operation of instruments are discussed, and results are compared with values available in the literature. Additional discussions address the sources of error and estimated uncertainties in the reported values.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

An Integrated Flame Spray Process for Low Cost Production of Battery Materials for Lithium Ion Batteries and Beyond

The overall objective of this project was to develop an advanced manufacturing technology for Li-ion battery materials production at low cost and in a green chemical process using glycerol as solvent to replace water. It was aimed at developing a prototype pilot production line to reduce production cost by at least 25% to the baseline. During the course of this project, research was conducted to understand spray drying and combustion of eutectic solvent precursors of glycerol and metal salts (acetates) in the formation of mixed metal oxide powders. Reactor design and optimization were done to facilitate spray drying and combustion in powder formation and processing. Various cathode materials powders were produced, including lithium nickel-cobalt-manganese oxide (NCM) and lithium nickel-cobalt-aluminum oxide (NCA). These cathode materials powders were tested in half coin cells for their performances, with materials performances of 160 mAh/g for NCM111 and 200 mAh/g for NCA. NCA powders were also produced using a slurry spray-drying process and tested in full pouch cells. A pilot scale flame assisted spray drying reactor was constructed and demonstrated for its production rate exceeding the target of production rate of four metric tons per year. The work performed in this project has been documented in 9 peer reviewed journal publications, 8 conference presentations, and two IP disclosures/patent applications.

25 ENERGY STORAGE↗

Niowave Design and Analysis of a High Power Converter - FY 21

LANL provided support to Niowave Inc. on the design and analysis of the Mk. 4 and Mk. 5, 20 kW converter. The Mk. 4 converter design consisted of lead bismuth eutectic (LBE) flowing over a divider plate to create a waterfall. Niowave, with feedback from LANL, improved on the Mk.4 divider plate and “horn” region of the converter to create the Mk. 5 version of the converter.

42 ENGINEERING↗

Niowave: Flow measurement development - FY2022

It is critical to maintain proper flow rate of lead bismuth eutectic (LBE) for the operation of the Niowave converter. The high temperature of the LBE (> 200 °C) makes it difficult to purchase simple off the shelf flow meters. One method that can be used to measure the flow rate indirectly, is to use a venturi, with a known throat diameter and differential pressure measurement across the throat. LANL designed the venturi and after numerous iterations with vendors, narrowed down a differential pressure transducer to use with the venturi.

43 PARTICLE ACCELERATORS↗

Application of Liquid Metals in Nano Particles and Vitrimers (Summer Quarter Report)

The melting points of pure elemental metals can be decreased by forming liquid metal alloys at the eutectic point composition. Utilizing this unique characteristic, the desirable properties of electron rich metals can be incorporated into new materials and applications. Liquid metals can be made into nanoparticles (LMNP), allowing for increased surface areas of a highly tunable and functional metal oxide skins. Careful characterization is important for understanding LMNP with many methods available to not only investigate size and distribution, but also surface chemistries. This is a review article written to fulfill the UO KCGIP Masters Program requirements.

36 MATERIALS SCIENCE↗

Thermophysical Property Measurements of NaCl-UCl3

Describe the research (summary of Scope of Work and principal objectives of the CRADA): Argonne produced and measured thermochemical and thermophysical properties of eutectic NaCl-UCl 3 salt at several temperatures in the range of interest. (Note measurements made with UCl 3 instead of PuCl 3 at participant’s request.)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Neptunyl and Uranyl Peroxide Chemistry in Molten Salts, Uranyl Structures from Nature, and Thermodynamic Studies Extending into the Transuranium Elements (Final Report)

This project was initially funded in 2007 and the current technical report is for 2019-2022. The specific objectives of this project (2019-2022) were: (1) Synthesis of actinide peroxide compounds in molten salt eutectics, (2) Studies of new uranyl minerals with fascinating structures and compositions, (3) Drop-solution calorimetric studies of actinide compounds extending into the transuranium elements, with an emphasis on the uranyl-sulfate system, (4) Continuation of studies of uranyl vanadate clusters synthesized using ionic liquids, (5) The training of Ph.D. graduate students in actinide chemistry, and to introduce undergraduate students to actinide research through providing research assistantships and supervision. The report lists 67 archival journal papers describing the work, of which 23 were since 2019. Highlights of the work are summarized for the period 2019-2022.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Conceptual design for a blanket tritium extraction test stand

Tritium breeding is fundamentally required for a sustainable fusion fuel cycle, yet the technological readiness of blanket technology lags far behind other fusion systems. Breeder concepts are divided into solid and liquid media, where solid breeders typically rely on a sweep gas, such as helium, to carry away tritium from lithium containing ceramic materials, and liquid breeders produce tritium from lithium containing eutectics (e.g., PbLi) or molten salts (FLiBe). In each case, tritium must be harvested from the breeding medium. A promising method for tritium extraction is through a vacuum permeator, in which a concentration gradient from the tritium- containing fluid promotes diffusion through a membrane with high hydrogen permeability to the vacuum. This technology has been demonstrated for hydrogen gas systems using Pd and PdAg permeators, but relatively little work has been done to test tritium extraction from PbLi. A Tritium Extraction eXperimental (TEX) loop is being designed to test tritium extraction in a vacuum permeator configuration. The system design is such that it will allow the testing of tritium extraction from both helium and PbLi. A phased approach is being taken that will allow testing of small specimens for fundamental permeation measurements, to multi-meter component testing at near-prototypic conditions. A molten PbLi loop is challenging due to the toxic and explosive nature of Pb and Li, respectively, radiological concerns by introducing tritium, and high temperatures involved in such a system. In addition, PbLi corrosion is a significant issue at high temperatures (>400C). The TEX system will not employ a neutron source for volumetric production of tritium. Herein we present the design and methods used for 1) pumping PbLi, 2) introducing deuterium or tritium into the PbLi, 3) quantifying the amount of deuterium in the loop, 4) extracting deuterium and tritium, and 5) quantifying the total amount of extracted deuterium or tritium from the permeator. In addition, the safety design for operating such a system will be discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

High Energy Aqueous Lithium-Ion Batteries (Final Report)

Lithium-ion batteries (LIBs) are a widely used energy storage device. For decades, researchers have been studying aqueous electrolytes due to their non-flammability and environmental friendless. However, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of water greatly limit the voltage window of the aqueous electrolyte. The recent concept of ‘solvent-in-salt’ electrolytes, namely ‘water-in-salt’ electrolytes (WISE) for aqueous batteries and ‘super-concentrated’ electrolytes for non-aqueous batteries, greatly expands the electrochemical window of these battery systems and consequently their energy density. This expansion occurs because the large number of salt aggregates in ‘solvent-in-salt’ electrolytes enables preferential salt decomposition over solvent decomposition to form robust interphase layers on electrodes, thus enhancing their stability in a wide range of operating voltages. However, even when the salt concentration reached 63m, regardless of cost, the cathodic potential of the WISE expanded only to 1.75V with an overall electrochemical stability window of <3.25V. To design the next generation of high energy aqueous LIBs, electrolytes that possess a wider electrochemical stability window and lower cost but still maintain the merit of non-flammability are much needed. In this project, we designed the aqueous LIBs with widened voltage window. We reported a cheap and non-flammable ternary eutectic electrolyte that can form a robust solid electrolyte interface (SEI)so that the cathodic limiting potential can be decreased to <1.5 V for Li 4 Ti 5 O 12 anodes, while maintaining both a high ionic conductivity of >10 -3 S cm –1 and a low viscosity. We demonstrated the super-stable2.5V LiMn 2 O 4 ||Li 4 Ti 5 O 12 pouch cell with mass loading of 2.5 mAh/cm. Further, LiCl-LiBr-Graphite/Li full cells were designed with high energy density. Finally, we use a bi-layer design to enlarge the voltage window of aqueous electrolyte, which can endow the stable cycling of aqueous Lithium metal batteries.

25 ENERGY STORAGE↗

Electrorefining Bismuth Using AC Superimposed DC Waveforms

Bismuth has been successfully electrorefined using both direct current (DC) and alternating current (AC) superimposed DC waveforms on a kilogram scale at Brigham Young University (BYU) in Provo, Utah. Finding a suitable surrogate for Pu Electrorefining has always been a technical challenge. This work allows the possibility to improve Pu electrorefining with nonradioactive material at universities, which greatly reduces the cost at Lawrence Livermore National Laboratory (LLNL) for improving Pu Electrorefining. Several possible surrogates (Ce, In, Sn, Zn, and Bi) were selected based on their ability to mimic the Pu electrorefining process. Ce and In electrorefining experiments were conducted at the same temperature as Pu electrorefining in CaCl 2 while Sn, Zn, and Bi, electrorefining experiments were conducted at a lower temperature in a eutectic molten salt composed of LiCl, KCl, and CaCl 2 . The electrorefining experiments using Ce with a Ga impurity did not produce a cathode ring. While the remaining Ce anode after electrorefining was significantly less than what was initially added, Scanning Electron Microscopy with Energy Dispersive X-Ray (SEM-EDX) analysis showed that the Ce had been oxidized and formed a colloid with the surrounding molten salt. This is supported in the literature by analysis of Ce-rich CaCl 2 mixtures. All the electrorefining experiments except for the Ce electrorefining experiments did not introduce an impurity to the system. Electrorefining experiments with In showed that the InCl 3 volatilized out of the molten salt to an extent that only a low current (<<1 A) could be supported without decomposing the molten salt. Zn electrorefining experiments had marginal success, however an easily separable product was not formed. The Zn had to be rinsed from the salt after the experiment. Of the identified potential surrogates. Investigated, only Bi and Sn yielded an easily separable product ring, which enables quantitative analysis of yields and coulombic efficiencies. Bismuth was first identified as a surrogate at BYU, while Sn was identified as a surrogate at LLNL later. Thus, the electrorefining experiments conducted at BYU using AC superimposed DC waveforms used Bi as the metal to be electrorefined.

36 MATERIALS SCIENCE↗