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At least 91 records · Page 5

Integration of safety engineering into a cost optimized development program.

A six-segment management model is presented, each segment of which represents a major area in a new product development program. The first segment of the model covers integration of specialist engineers into 'systems requirement definition' or the system engineering documentation process. The second covers preparation of five basic types of 'development program plans.' The third segment covers integration of system requirements, scheduling, and funding of specialist engineering activities into 'work breakdown structures,' 'cost accounts,' and 'work packages.' The fourth covers 'requirement communication' by line organizations. The fifth covers 'performance measurement' based on work package data. The sixth covers 'baseline requirements achievement tracking.'

Ball, L. W.↗

Annual Status Update for OWL

This report represents completion of milestone deliverable M2SF-22SN010309082 Annual Status Update for OWL, which is due on November 30, 2021 as part of the fiscal year 2022 (FY2022) work package SF-22SN01030908. This report provides an annual update on status of FY2021 activities for the work package “OWL - Inventory – SNL”. The Online Waste Library (OWL) has been designed to contain information regarding United States (U.S.) Department of Energy (DOE)-managed (as) high-level waste (DHLW), DOE-managed spent nuclear fuel (DSNF), and other wastes that are likely candidates for deep geologic disposal. Links to the current supporting documents for the data are provided when possible; however, no classified or official-use-only (OUO) data are planned to be included in OWL. There may be up to several hundred different DOE-managed wastes that are likely to require deep geologic disposal. This report contains new information on sodium-bonded spent fuel waste types and wastes forms, which are included in the next release of OWL, Version 3.0, on the Sandia National Laboratories (SNL) External Collaboration Network (ECN). The report also provides an update on the effort to include information regarding the types of vessels capable of disposing of DOE-managed waste.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

High Altitude Long Endurance Remotely Operated Aircraft - National Airspace System Integration - Simulation IPT: Detailed Airspace Operations Simulation Plan. Version 1.0

The primary goal of Access 5 is to allow safe, reliable and routine operations of High Altitude-Long Endurance Remotely Operated Aircraft (HALE ROAs) within the National Airspace System (NAS). Step 1 of Access 5 addresses the policies, procedures, technologies and implementation issues of introducing such operations into the NAS above pressure altitude 40,000 ft (Flight Level 400 or FL400). Routine HALE ROA activity within the NAS represents a potentially significant change to the tasks and concerns of NAS users, service providers and other stakeholders. Due to the complexity of the NAS, and the importance of maintaining current high levels of safety in the NAS, any significant changes must be thoroughly evaluated prior to implementation. The Access 5 community has been tasked with performing this detailed evaluation of routine HALE-ROA activities in the NAS, and providing to key NAS stakeholders a set of recommended policies and procedures to achieve this goal. Extensive simulation, in concert with a directed flight demonstration program are intended to provide the required supporting evidence that these recommendations are based on sound methods and offer a clear roadmap to achieving safe, reliable and routine HALE ROA operations in the NAS. Through coordination with NAS service providers and policy makers, and with significant input from HALE-ROA manufacturers, operators and pilots, this document presents the detailed simulation plan for Step 1 of Access 5. A brief background of the Access 5 project will be presented with focus on Steps 1 and 2, concerning HALE-ROA operations above FL400 and FL180 respectively. An overview of project management structure follows with particular emphasis on the role of the Simulation IPT and its relationships to other project entities. This discussion will include a description of work packages assigned to the Simulation IPT, and present the specific goals to be achieved for each simulation work package, along with the associated deliverables necessary to achieve these goals and the needs of other Access 5 IPTs. The simulation environment chosen for this task is then outlined. This section includes a description of the system architecture, a list of the necessary assumptions made by the Simulation IPT, and the roles, responsibilities and interactions of simulation participants. The method of simulation conduct is presented in the next section with particular emphasis on scenario development and applicability to evaluation of Step 1 HALE-ROA operations. Following, data collection and analysis methods are discussed for air traffic specialists and air vehicle control station operators. Lastly, a schedule of Step 1 simulation activities is presented for reference.

Source record↗

Development of an Electrochemical Impedance Instrument for Monitoring Corrosion Formation (Oxide and Hydride) on Cladding Materials

The objective of this work package is to develop electrochemical impedance spectroscopic (EIS) techniques for the in pile measurement of changes in cladding materials in coupling with model simulation and material characterization. This work package will involve the initial development of electrochemical sensing technologies for measuring spatial and time resolved changes in cladding chemistry. Specific attention will be paid to monitoring changes in monitor cladding corrosion including oxide and hydride formation and deformation. The planned work during this period was focused on cladding material zirconium alloy corrosion, oxide and hydride development, and to characterize samples using EIS under controlled gas atmosphere, atom probe tomography (APT), Raman Spectroscopy, and Synchrotron X-ray diffraction (XRD). The corrosion, including oxide and hydride of zirconium alloy samples, was tested in this study. The samples were treated at a gas environment containing 3% H2 (vol%) balanced with N2 gas at various temperatures (100 – 500°C) and different times (up to 60 hours) and were characterized by in situ EIS. After treatment, various characterization techniques were applied to measure the samples, including TGA, Ramen, XRD, and APT. This study found that impedance spectra can be affected significantly with (furnace/environment) temperature. Higher temperature resulted in higher overall impedance, and longer exposure time exerted similar effects. Proof of concept characterization of oxidized samples, including TGA, Raman, XRD, and APT, were accomplished on samples exposed to 700 oC gas environment containing 20% O2 and 80% N2. TGA provides observable breakaway and bulk oxide growth measurements. High-temperature, in-situ Raman provides observation of oxidation stress at the surface of the oxide. Additionally, a transition from tetragonal to monoclinic zirconia can be seen early in the oxidation experiment. Specifically, tetragonal-rich zirconia is seen at the metal/oxide interface, where a transition to monoclinic-rich zirconia is seen in the bulk of the oxide. It has also been confirmed that highly compressive residual stresses are seen near the metal/oxide interface. It is concluded that the transition from tetragonal to monoclinic zirconia is induced by massive shifts in stress as the oxide grows. APT has supplied evident differences in the distribution of zirconium and oxygen at the metal/oxide interface. On the pre-breakaway sample, the metastable Zr(O) region at the boundary is relatively thin, interfaced by Zr-rich (i.e., metal) and O-rich (i.e., ZrO2) on either side. In contrast, it has been seen on a post-breakaway sample that the Zr(O) metastable region is much greater in thickness, with evidence of four “zones” showing slightly contrasting composition between 49-54% Zr. In addition, it can be seen from the Zr-2.65Nb post-breakaway sample that secondary element concentrations are considerably different than bulk composition measurements show. Specifically, Nb concentration is much lower than expected, whereas Fe concentration is much higher than expected. These differences could play a role in each element’s contribution to oxide growth mechanisms, as well as causation for breakaway. Future work is focused on analyzing EIS spectra of hydride and its correlation with characterization features, finite element (FE) modeling of cladding materials, electrochemical sensor development, targeting cladding oxides/hydrides under thermodynamic equilibria, during transients and under irradiation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

FY 2017-Progress Report on the Design and Construction of the Sodium Loop SMT-3

This report provides an update on the design of a forced-convection sodium loop to be used for the evaluation of sodium compatibility of advanced Alloy 709 with emphasis on long term exposures of tensile, creep, fatigue, creep fatigue, and fracture toughness ASTM-size specimens in support of ASME Code qualification and NRC licensing. The report is a deliverable (Level 4) in FY17 (M4AT-17AN1602094), under the Work Package AT-17AN160209, “Sodium Compatibility” performed by Argonne National Laboratory (ANL), as part of the Advanced Materials Program for the Advanced Reactor Technology. This work package enables the development of advanced structural materials by providing corrosion, microstructure, and mechanical property data from the standpoint of sodium compatibility of advanced structural alloys. The first sodium loop (SMT-1) with a single tank was constructed in 2011 at ANL and has been in operation for exposure of subsize sheet specimens of advanced alloys at a single temperature. The second sodium loop with dual tanks (SMT-2) was constructed in 2013 and has been in operation for the exposure of subsize sheet specimens of advanced alloys at two different temperatures. The current loop (SMT-3) has been designed to incorporate sufficient chamber capacity to expose a large number of ASTM-size specimens to evaluate the sodium effects on tensile, creep, fatigue, creep-fatigue, and fracture toughness properties, in support of ASME Code Qualification and USNRC Licensing. The design of individual components for the third sodium loop SMT-3 is almost complete. The design also has been sent to an outside vendor for piping analysis to be in compliance with ASME Code. A purchase order has been placed with an outside vendor for the fabrication of major components such as the specimen exposure tanks. However, we have contracted with another vendor to establish the piping design in compliance with ASME design codes. The piping design was completed in FY2017 and the information is being transmitted to the tank fabricator. The SMT-3 loop will be located in Building 206 adjacent to the currently operating SMT-2 loop. In addition, we have demolished the aged power supply system in Building 206 and installed a new transformer, wiring, and power panels for the new loop. Procurement of some of the long lead items such as valves, EM pumps, EM flowmeters, etc. is in progress and will continue in FY 2018. The construction of components such as cold trap, economizers, piping arrangement etc. will be performed in the central shops at ANL. About 150 liters of sodium for the loop will be procured in early FY2018. The loop system is designed to circulate sodium through the sample tanks and the associated loop without an operator for an extended period of time. With the three sodium loops (with single-tank, dual-tank and four–tanks), materials can be tested at different sodium temperatures, and large tensile, creep, fatigue, creep-fatigue, and fracture toughness specimens can be exposed to sodium for extended periods of time and generate data on mechanical properties in support of ASME Code Qualification and USNRC Licensing of advanced Alloy 709 for use as a structural material in SFRs.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Documenting Development of Processing Parameters for Fabrication of Doped and Undoped Fuel Pellets (Summary Report)

Early FY20 restructuring of the TREAT work package FT-20LA02020608 Enriched Fuel Fabrication for Safety Testing, and associated deliverables necessitated the rescoping of existing LANL deliverables. This rescoped carryover report summarizes work to date on doped and undpoped fuel pellet fabrication development of proceeding parameters. This summary also includes a status update of intended research activities that fall under the activity associated with this work package.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Report on the completion of long-lead components procurement of new sodium materials test loop

This report provides an update on the completion of long-lead components procurement of new sodium materials test loop. The loop, designated as SMT-3, is a forced-convection sodium loop to be used for the evaluation of sodium compatibility of advanced Alloy 709 with emphasis on long term exposures of tensile, creep, fatigue, creep fatigue, and fracture toughness ASTM-size specimens in support of ASME Code qualification and NRC licensing. The report is a deliverable (Level 4) in FY18 (M4NT-18AN050503013), under the Work Package NT-18AN05050301, “A709 Sodium Compatibility” performed by Argonne National Laboratory (ANL), as part of the Advanced Materials Program for the Advanced Reactor Technology. This work package enables the development of advanced structural materials by providing corrosion, microstructure, and mechanical property data from the standpoint of sodium compatibility of advanced structural alloys. The first sodium loop (SMT-1) with a single tank was constructed in 2011 at ANL and has been in operation for exposure of subsize sheet specimens of advanced alloys at a single temperature. The second sodium loop with dual tanks (SMT-2) was constructed in 2013 and has been in operation for the exposure of subsize sheet specimens of advanced alloys at two different temperatures. The current loop (SMT-3) has been designed to incorporate sufficient chamber capacity to expose a large number of ASTM-size specimens to evaluate the sodium effects on tensile, creep, fatigue, creep-fatigue, and fracture toughness properties, in support of ASME Code Qualification and USNRC Licensing. Three major long lead items were identified: 1) Selection and approval of location for the new loop and installation of the necessary infrastructure, such as transformer, power supply panels, and wiring, that is adequate for the long term operation of the loop, 2) Perform a detailed piping analysis that meets the ANL QA and Safety guidelines as well as complying with ASME Code requirements, and 3) Design and fabrication of the specimen exposure vessels that are capable of at least 42 tensile, creep, and fatigue specimens in each vessel and is compliant and compatible with ASME Code and the piping design analysis. The SMT-3 loop will be located in Building 206 adjacent to the currently operating SMT-2 loop. In addition, we have removed the aged power supply system in Building 206 and installed a new transformer, wiring, and power panels for the new loop. The preliminary loop design was sent to an outside vendor for a detailed piping analysis, to ensure compliance with the ASME Code guidelines. The piping design was completed in FY2017. The construction of components such as cold trap, economizers, piping arrangement etc. will be performed in the central shops at ANL. About 150 liters of sodium for the loop will be procured in early FY2018. The loop system is designed to circulate sodium through the sample tanks and he associated loop without an operator for an extended period of time. With the three sodium loops (i.e., single-tank, dual-tank and four–tank), materials can be tested at different sodium temperatures, and large tensile, creep, fatigue, creep-fatigue, and fracture toughness specimens can be exposed to sodium for extended periods of time and generate data on mechanical properties in support of ASME Code Qualification and USNRC Licensing of advanced Alloy 709 for use as a structural material in SFRs.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

(M4CT-18IN0707093) Investigating Electrochemical Impedance Spectroscopic (EIS) Measurement of Surrogate Oxide at High Temperatures

The objective of this work package is to develop electrochemical impedance spectroscopic (EIS) techniques for the in-pile measurement of changes in solid state chemistry of fuels and materials in coupling with model simulation and material characterization. This work package will involve the initial development of electrochemical sensing technologies for measuring spatial- and time-resolved changes in fuel and cladding chemistry. Specific attention will be paid to monitoring changes in fuel stoichiometry, monitor cladding hydride formation and deformation, and cladding corrosion. The planned work during this period was focused on theoretical investigation on high temperature impedance of material, establishing experimental capabilities, including high temperature EIS under controlled gas atmosphere, atom probe tomography (APT), Raman Spectroscopy, and Synchrotron XRD. Future work will focus on starting the electrochemical sensor development, targeting the dielectric response of oxide fuels and cladding oxides/hydrides under thermodynamic equilibria, during transients, and under irradiation. Three main achievements are summarized in this report for the FY17 carry-over. First, theoretical investigation on high temperature impedance of material were conducted and spatial distribution of defects and equivalent resistivity in stoichiometric oxides under a temperature gradient were analyzed. Second, a laboratory for EIS measurement at high temperature was established and the laboratory instruction (LI) for conducting experiments was approved; and the impedance of CeO2 at 800 C was examined and its electrical conductivities were analyzed and compared with other reported data. In addition, the capabilities of advanced characterization wer established including high temperature Ramen, atom probe tomography (APT) and SEM, and samples including Zr4 and CeO2 were characterized.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Development of Refractory Alloys and Refractory Coatings for Advanced Nuclear Reactors

The next generation of nuclear reactors will benefit from materials that enable operation at higher temperatures (>500°C), higher irradiation doses (up to 200 displacements per atom (dpa)), and the use of more corrosive and reactive coolants. This work package represents the first experimental steps towards a longer-term effort to develop refractory materials for nuclear energy applications which will enable operation under these conditions. Specifically, this work package focuses on additive manufacturing of refractories as both a refractory liner coating deposited onto the interior surface of a metallic tubular backbone and as bulk refractory alloys. During fiscal year 23 (FY23), several refractory metal coating systems and bulk alloys were examined and selected using a decision criteria matrix. The refractory metal coating systems included molybdenum, tungsten, and zirconium as refractory coatings on backbones of either carbon-carbon (C/C) or silicon carbide-silicon carbide (SiC/SiC) ceramic matrix composites. The bulk refractory alloys included C-103, WTa, and WNiFe as bulk alloys. During FY24 additional bulk refractory alloys and metallic backbones were evaluated using the decision criteria matrix based on input from the AMMT leadership team. These included 316 SS and 316H SS for the metallic backbones and Mo-La, Ta, and Nb1Zr as bulk refractory alloys. The primary focus for the FY24 effort was placed on establishing the capabilities to deposit refractory coatings based on the results of the scoring in the decision criteria matrix and finalizing the additively manufactured TZM studies which were incorporated into the AMMT program from the microreactor program. Further efforts were dedicated to establishing the capabilities to additively manufacture down-selected bulk refractory alloys.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Non-LWR Regulatory Framework Modernization

This report provides a summary of Fiscal Year 2025 activities performed in the Regulatory Framework Modernization work package through July 2025. This reflects the progress and status of Idaho National Laboratory?s activities concerning the development of an advanced reactor regulatory framework and its implementation in the United States. This report includes discussions of the progress that NRC has made on the ADVANCE Act requirements as well as the newly issued Presidential Executive Orders from May 2025. It provides a summary of the additional work packages added in July 2025 because of the executive orders. The report also provides recommendations for work to be performed in Fiscal Year 2026. This work was supported by the U.S. Department of Energy Office of Nuclear Energy Regulatory Development subprogram. These activities are managed by Idaho National Laboratory on behalf of the Department of Energy.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Design of Instrumentation for Noble Gas Transport in LSTL Needed for Model Development

Development of molten salt reactors (MSRs) requires consideration of several physical phenomena that are different from the light water reactor (LWR) experience. While small-scale tests have been performed to understand the behavior of molten salts, the scale-up to larger experiments is an important step in the development of MSR designs. These small-scale experiments have given information on the thermodynamic state of the heat transport fluid and its constituents, thermophysical properties, convective flow, and corrosion. As detailed models have been developed, using these models to simulate larger scale experiments must incorporate physics that becomes important during scale-up, temperature inhomogeneities, complex flow behavior, and two-phase flow. The purpose of the work package has been to link experimental and modeling efforts in the support of licensing development to design and evaluate technologies to mitigate radionuclide release from MSRs. There were two main activities in this work package—one investigating fission product transport into the cover gas and the other on fission gas transport in the molten salt.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Materials for the General Aviation Industry: Effect of Environment on Mechanical Properties of Glass Fabric/Rubber Toughened Vinyl Ester Laminates

A screening evaluation is being conducted to determine the performance of several glass fabric/vinyl ester composite material systems for use in primary General Aviation aircraft structures. In efforts to revitalize the General Aviation industry, the Integrated Design and Manufacturing Work Package for General Aviation Airframe and Propeller Structures is seeking to develop novel composite materials and low-cost manufacturing methods for lighter, safer and more affordable small aircraft. In support of this Work Package, this study is generating material properties for several glass fabric/rubber toughened vinyl ester composite systems and investigates the effect of environment on property retention. All laminates are made using the Seemann Composites Resin Infusion Molding Process (SCRIMP), a potential manufacturing method for the General Aviation industry.

McBride, Timothy M.↗

OC7 Phase I Definition Document

The Offshore Code Comparison Collaboration 7 (OC7) project is organized under the International Energy Agency Wind Technology Collaboration Programme Task 56 with an objective to evaluate and enhance the predictive accuracy of engineering-level modeling tools used in the design of offshore wind energy systems. Phase I of OC7 is focused on improving the models and modeling practices of hydrodynamic viscous loads on floating offshore wind turbine platforms. In alignment with this goal, Work Package 1.1 of OC7 Phase I is formulated to investigate the modeling of hydrodynamic viscous loads on several different geometric components commonly encountered with floating offshore wind platform designs, including cylindrical columns, heave plates, and rectangular pontoons. Work Package 1.1 also explores the dependence of hydrodynamic coefficients on the sea state to drive toward practical guidance on how these coefficients can be selected or adjusted for different conditions. This report outlines the motivation and objectives behind each subphase of OC7 Phase I, along with the necessary technical specifications and load case definitions to guide the project participants. It also serves as an important part of the project documentation for future modelers who would like to reproduce this work or make use of the data and information generated from the OC7 project.

17 WIND ENERGY↗

M4SF-17LL010301071: Thermodynamic Database Development

This progress report (Level 4 Milestone Number M4SF-17LL010301071) summarizes research conducted at Lawrence Livermore National Laboratory (LLNL) within the Argillite Disposal R&D Work Package Number M4SF-17LL01030107. The DR Argillite Disposal R&D control account is focused on the evaluation of important processes in the analysis of disposal design concepts and related materials for nuclear fuel disposal in clay-bearing repository media. The objectives of this work package are to develop model tools for evaluating impacts of THMC process on long-term disposal of spent fuel in argillite rocks, and to establish the scientific basis for high thermal limits. This work is contributing to the GDSA model activities to identify gaps, develop process models, provide parameter feeds and support requirements providing the capability for a robust repository performance assessment model by 2020.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Process–Property–Performance Mapping of Additively Manufactured 316H Stainless Steel Components

The Advanced Materials and Manufacturing Technologies Program is focused on accelerating the development of advanced materials and components fabricated via additive manufacturing, and is using laser powder bed fusion (LPBF) of 316H stainless steel as an initial case study. In the previous fiscal year, miniature high-throughput specimens were printed on multiple LPBF systems to provide initial processing windows to minimize porosity and limit epitaxial grain growth during prints. This fiscal year, scaled builds were completed on three different LPBF systems at ORNL: a GE Concept Laser M2, a Renishaw AM400, and an EOS M290. Builds on the Concept Laser were conducted on multiple powder lots and processing parameter ranges to provide microstructure effects on time-independent and time-dependent mechanical properties. Builds on the Renishaw were produced using Oak Ridge National Laboratory (ORNL)-optimized printing parameters and Argonne National Laboratory (ANL)-optimized printing parameters to compare outcomes of parallel process optimization efforts at different national laboratories on the same LPBF system. Similarly, the build completed on the EOS M290 replicated the processing parameters of builds completed at Los Alamos National Laboratory (LANL). Optical microscopy and electron backscatter diffraction characterization was completed on all builds. In addition to the general round robin characterization, this work-package generated time-independent data, including tensile and fracture toughness test data on scaled Concept Laser builds as a function of processing parameters and post-build heat treatment. This analysis is complimentary to work in parallel work packages aiming to establish heat treatment and processing effects on time-dependent properties. It was found that although the stress-relief heat treatment provides the highest strength at lower-temperatures, tensile strength begins to converge at higher temperatures regardless of heat treatment condition. In addition, the more rigorous solution annealing and hot-isostatic pressing post-build heat treatments result in higher fracture toughness than the stress-relieved condition. The root-causes of the lower fracture toughness of the stress-relieved LPBF 316H material was informed via a stress-relief optimization study on a scaled concept laser print, where it was found that although dislocation recovery was largely complete after only a couple hours at 650°C, the extended hold of the current 24h heat treatment employed on scaled builds likely caused increased carbide volume fractions along the LPBF 316H grain boundaries, thereby deteriorating crack propagation resistance. This trend was seen to become more deleterious with additional increases of stress-relief temperature to 750°C or 850°C. These results have helped inform a new optimal stress-relief annealing condition for LPBF 316H for future campaign testing (650°C for 2h).

36 MATERIALS SCIENCE↗

Process–Property–Performance Mapping of Additively Manufactured 316H Stainless Steel Components

The Advanced Materials and Manufacturing Technologies Program is focused on accelerating the development of advanced materials and components fabricated via additive manufacturing, and is using laser powder bed fusion (LPBF) of 316H stainless steel as an initial case study. In the previous fiscal year, miniature high-throughput specimens were printed on multiple LPBF systems to provide initial processing windows to minimize porosity and limit epitaxial grain growth during prints. This fiscal year, scaled builds were completed on three different LPBF systems at ORNL: a GE Concept Laser M2, a Renishaw AM400, and an EOS M290. Builds on the Concept Laser were conducted on multiple powder lots and processing parameter ranges to provide microstructure effects on time-independent and time-dependent mechanical properties. Builds on the Renishaw were produced using Oak Ridge National Laboratory (ORNL)-optimized printing parameters and Argonne National Laboratory (ANL)-optimized printing parameters to compare outcomes of parallel process optimization efforts at different national laboratories on the same LPBF system. Similarly, the build completed on the EOS M290 replicated the processing parameters of builds completed at Los Alamos National Laboratory (LANL). Optical microscopy and electron backscatter diffraction characterization was completed on all builds. In addition to the general round robin characterization, this work-package generated time-independent data, including tensile and fracture toughness test data on scaled Concept Laser builds as a function of processing parameters and post-build heat treatment. This analysis is complimentary to work in parallel work packages aiming to establish heat treatment and processing effects on time-dependent properties. It was found that although the stress-relief heat treatment provides the highest strength at lower-temperatures, tensile strength begins to converge at higher temperatures regardless of heat treatment condition. In addition, the more rigorous solution annealing and hot-isostatic pressing post-build heat treatments result in higher fracture toughness than the stress-relieved condition. The root-causes of the lower fracture toughness of the stress-relieved LPBF 316H material was informed via a stress-relief optimization study on a scaled concept laser print, where it was found that although dislocation recovery was largely complete after only a couple hours at 650°C, the extended hold of the current 24h heat treatment employed on scaled builds likely caused increased carbide volume fractions along the LPBF 316H grain boundaries, thereby deteriorating crack propagation resistance. This trend was seen to become more deleterious with additional increases of stress-relief temperature to 750°C or 850°C. These results have helped inform a new optimal stress-relief annealing condition for LPBF 316H for future campaign testing (650°C for 2h).

36 MATERIALS SCIENCE↗

Unsaturated alluvium disposal modelling with improved geological realism

This report describes specific activities in the Fiscal Year (FY) 2023 associated with the Geologic Disposal Safety Assessment (GDSA) Repository Systems Analysis (RSA) work package funded by the Spent Fuel and Waste Science and Technology (SFWST) Campaign of the U.S. Department of Energy Office of Nuclear Energy (DOE-NE), Office of Spent Fuel and Waste Disposition (SFWD). The overall objective of the GDSA RSA work package is to develop generic deep geologic repository concepts and system performance assessment (PA) models in several potential host-rock environments, and to simulate and analyze these generic repository concepts and models using the GDSA Framework toolkit and other tools as needed. The specific GDSA goal addressed in this report is reference case development, simulation, and analysis for the unsaturated alluvium (UZ), one of the four potential host-rocks considered by the GDSA. Further, we aim to exercise the simulation tools and methodologies under development by GDSA for PA modelling.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Laser Powder Bed Fusion of Steels for Nuclear Applications

This report provides an update on laser powder bed fusion of steels for nuclear applications. This report is a Milestone 3 deliverable in FY2024, under work package CT-24AN130401 to support research and qualification activities supported by the Advanced Materials and Manufacturing Technologies (AMMT) program here at Argonne National Laboratory (ANL). Continuing from FY23, the focus of FY24 for ANL includes further optimization of process parameters for three alloys: A709, G91, G92. The work package also includes fabricating test samples to conduct a thorough microstructural analysis and perform preliminary mechanical testing. For the same, we have used CALPHAD-based thermodynamic kinetic modeling to optimize the experimental activities.

36 MATERIALS SCIENCE↗