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All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Draft ASME Boiler and Pressure Vessel Code Cases and Technical Bases for Use of Alloy 617 for Constructions of Nuclear Component Under Section III, Division 5

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code currently only allows five materials for use in construction of nuclear components for high temperature service. These are: 2.25Cr-1Mo and V-modified 9Cr-1Mo steels, Types 304 and 316 stainless steels and the high nickel Alloy 800H. Since 2005, the US high temperature gas-cooled reactor program has been characterizing elevated temperature mechanical properties of Alloy 617 as the leading candidate construction material for the intermediate heat exchanger. After analysis of these experimental results, along with historical data and additional results available through the Generation IV International Forum, Very High Temperature Reactor, Materials Program Management Board Materials Handbook, a draft ASME Code Case to allow nuclear construction with Alloy 617 for temperatures up to 1750°F (954°C) has been developed. This report contains the Code Case for Low Temperature Service Construction of Section III, Division 5, Subsection HB, Subpart A, Class A and Subsection HC, Subpart A, Class B components, which has been approved in Section II, Materials, and Section III, Rules for Construction of Nuclear Facility Components. Supporting technical justification for the low temperature Code Case is also included. This Code Case allows use of Alloy 617 up to 800°F (425°C). This report also contains an updated draft of a Section III, Division 5, Subsection HB, Subpart B, Class A Code Case for Alloy 617 to qualify it for use in construction of nuclear components up to 1750°F (954°C) for service life up to 100,000 hours. The draft contained in Appendix 4, subject to editorial revision and approval by the ASME Special Task Group on Alloy 617 Code Qualification, will be submitted for approval by letter ballot by the appropriate ASME Committees. The technical justification supporting the Code Case is presented in Appendix 5 of this report. This background document is part of the information package that will be submitted with the Code Case for ballot.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Design of Multi-Stage Solvent Extraction Process for Separation of Rare Earth Elements

Flowsheet design and stage determination for the separation of rare earth elements (REEs) using solvent extraction (SX) is a challenging task because of the chemical similarity of the REEs. Low separation factors between the elements and complex equilibrium chemistry provide unique challenges to designing an efficient flowsheet for the separation of elements. The multi-stage nature of the SX process adds further complexity, making the assessment of products for a proposed design and stage combination difficult. Therefore, to develop a SX flowsheet, it is essential to quantify the performance for various design and separation conditions. This paper attempts to address the challenge by utilizing an equilibrium and process modeling approach. Results from a bench-scale study performed on a 10 g/L rare earth salt mixture were used in studying the extraction/stripping behavior and developing equilibrium models. DEHPA with TBP as a phase modifier was used as an extractant, while hydrochloric acid was utilized as a stripping agent. The results obtained were used in developing extraction/stripping models, which were integrated into a process framework of a SX train in a Matlab/Simulink environment. The models were programmed as a function block routine and used for developing a flowsheet, which was simulated for differing separation and design conditions. To identify optimum stage combinations, a particle swarm optimization (PSO) routine was developed and implemented for each SX train. Recovery and purity of elements of interest were used as objective function criteria. The stage combination leading to the minimization of the objective function was used to identify the optimum stage combination for a series of SX trains to attempt a balance of purity and recovery. The models and optimization method were implemented to separate a feed mixture containing REEs, which indicated that 99.52 and 85.41 percent purity is achievable for Yttrium and Lanthanum separation using 8-12-3 and 10-3-5 stage combination for loading, scrubbing, and striping. The model also indicated difficult separability between neodymium, praseodymium, and cerium.

Srivastava, Vaibhav (ORCID:0000000212645987)↗
DOE OSTI2021

Software Quality Assurance for EBR-II Fuels Irradiation and Physics Database (FIPD)

The Fuels Irradiation and Physics Database (FIPD) is an ongoing DOE project on archival of the EBR-II metal-alloy fuel irradiation experiments. As part of its use in support of license applications, the Quality Assurance Program Plan (QAPP) was drafted and endorsed by NRC in an effort to demonstrate its compliance with regulatory expectations. Software Quality Assurance (SQA) for the physics portion of FIPD is intended to qualify the calculated quantities such as fuel and cladding temperatures, neutron fluence and axially varying burnup estimates for irradiated fuel elements. This report covers the initial evaluation of SQA status of three neutron physics and thermo-fluid codes (REBUS, RCT and SE2RCT) that form the basis of calculated quantities for as-irradiated characteristics of the tested metallic fuel elements. The report also introduces an SQA plan to address the identified deficiencies. The REBUS, RCT, and SE2RCT codes are all part of the Argonne Reactor Code (ARC) code system. There is considerable knowledge and experience on REBUS and RCT but relatively less on SE2RCT. During FY2021, efforts focused on an assessment of how the data in the EBR-II Physics and Analysis DataBase (PADB) is generated with SE2RCT and used in FIPD. Additional tasks included considerations of uncertainties for power estimates in REBUS and RCT calculations and their impact on the combined RCT methodology. The RCT software usage in FIPD was assessed this year and the input/output details studied. A “requirements” document was created that identifies the key features of the RCT software being used in FIPD that need to have SQA documentation. A brief discussion on the history of RCT and its input is included in this report along with the basic SQA roadmap laid out in the requirements document. The SE2RCT software usage in FIPD is still being studied noting that there is no current manual. As part of the work done this year, two bugs were identified in the SE2RCT software which have a minor impact on the accuracy of the results it produces. No requirements document has been created, but one identified feature of SE2RCT being used that needs verification was its fuel pin temperature calculation. The work completed this year confirms that the approximations which will be included in the software verification report for SE2RCT are accurate. In addition to software quality assurance work for RCT and SE2RCT, an automated verification framework is proposed to simplify the software quality assurance process. The purpose of this framework is to streamline code verification and documentation while minimizing repetitive tasks for code developers and reviewers. The reduction of repeated input (between reference solution, software, and documentation input) throughout the SQA process reduces potential for human errors during the preparation of the supporting software quality records. The automation of the verification and documentation process proposed for this project leverages the existing verification structure already in place for the SAS4A/SASSYS-1 code.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

End-to-end learning of multiple sequence alignments with differentiable Smith–Waterman

Abstract Motivation Multiple sequence alignments (MSAs) of homologous sequences contain information on structural and functional constraints and their evolutionary histories. Despite their importance for many downstream tasks, such as structure prediction, MSA generation is often treated as a separate pre-processing step, without any guidance from the application it will be used for. Results Here, we implement a smooth and differentiable version of the Smith–Waterman pairwise alignment algorithm that enables jointly learning an MSA and a downstream machine learning system in an end-to-end fashion. To demonstrate its utility, we introduce SMURF (Smooth Markov Unaligned Random Field), a new method that jointly learns an alignment and the parameters of a Markov Random Field for unsupervised contact prediction. We find that SMURF learns MSAs that mildly improve contact prediction on a diverse set of protein and RNA families. As a proof of concept, we demonstrate that by connecting our differentiable alignment module to AlphaFold2 and maximizing predicted confidence, we can learn MSAs that improve structure predictions over the initial MSAs. Interestingly, the alignments that improve AlphaFold predictions are self-inconsistent and can be viewed as adversarial. This work highlights the potential of differentiable dynamic programming to improve neural network pipelines that rely on an alignment and the potential dangers of optimizing predictions of protein sequences with methods that are not fully understood. Availability and implementation Our code and examples are available at: https://github.com/spetti/SMURF. Supplementary information Supplementary data are available at Bioinformatics online.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Lamellar: A Rust-based Asynchronous Tasking and PGAS Runtime for High Performance Computing

Cybersecurity is one of the largest concerns in modern computing, impacting and dictating how governments, private corporations, and individuals interact with and live in an increasingly digital world. The NSA has recently released a memo [ 1] on “Software Memory Safety” where they highlight that both Microsoft and Google have stated around 70% of software vulnerabilities were due to memory safety issues. Although languages such as C and C++ provide freedom and flexibility with memory management, guaran- teeing safety falls mostly on the developer. The NSA recommends using “memory safe” languages whenever possible. In this paper we introduce Lamellar, an asynchronous tasking and PGAS HPC runtime written in Rust, one such "memory safe" language. We describe the entire Lamellar stack, from network interfaces to high- level abstractions such as distributed LamellarArrays and Active Messages. We conclude by showing comparable performance to legacy PGAS runtimes (e.g. OpenSHMEM) on a subset of the BALE kernel suite while maintaining strong memory safety principles.

HPC Software Systems, Rust Programming Language, P↗
DOE OSTI2022

Low-Cost Preform and Molding Processes

The entry cost for prototyping a composite component for manufacture using automated, high rate processes is prohibitively expensive in many cases, especially for small business, where tooling costs may be several $100k. Discussions with industry also indicate that many small companies, tier 1 and 2 suppliers, have an interest to mold composite parts but do not want to deal with the capital cost, material handling issues, and labor associated with dry fiber preforming operations. While the molders may locate near the end user for logistics reasons, it may be more cost effective for the performer to remain regional and invest in capital equipment to support preform automation, thus keeping costs to a minimum. This project was designed to explore and demonstrate several options to meet these industry needs. Dry fiber preforming approaches were evaluated which allow for low pressure resin infusion, single sided tooling options such a vacuum assisted resin transfer molding (VARTM) or low pressure resin transfer molding (RTM-light). Unlike sheet molding compound, SMC compression molding where typical molding pressures of 1000 psi are required to push material into the desired location; positioning of a dry fiber preform into the desired location on the tool allows for low molding pressures of 10-50 psi. Lower molding pressures allow for use of low cost, additive fabrication of polymeric tooling. Polymeric tooling is suitable for rapid part prototyping and limited production. Dry fiber preforming approaches evaluated included use of commercial chopped strand mat, robotic chopper gun deposition, and continuous fiber preform augmentation using tailored fiber placement (TFP). Use of chopped strand mat does not require a robotic deposition method, however a cutting table is generally required and there is typically 20-30% scrap generation. While various fiber areal weights are available, the preform is not readily optimized for minimal fiber use or weight savings. In contrast, a robotic chopper gun approach allows for localized deposition where fiber is required to meet structural requirements. The robotic method is highly automated and minimizes fiber scrap, however the capital cost of the equipment and engineering labor for programming can result in higher preform cost compared to chopped strand mat in certain cases depending on preform complexity. Dry fiber preforming using the robotic chopper gun method allows for creation of three dimensional forms. This approach may be ideal for molding in-house, or if the preforms stack together densely to allow for efficient shipping. Applications evaluated for this program considered trade-off between fabrication of a fully 3D preform versus production of a flat preform which is designed to readily drape into the final desired shape. Such a preform design greatly simplifies robotic programming and requires no specialized tooling. The flat preforms are easily stacked and shipped to the final molding location. Flat preforms are much easier to augment with TFP continuous fiber to provide local reinforcement. The demonstration and evaluation of these preforming and tooling methods were completed on three component applications. The first application was a battery box cover for an electric vehicle which was highly three dimensional. The second demonstrator article was comprised of complex contours and was used to demonstrate the use of TFP and RTM-light molding process. The third demonstration article was the roof of an operator’s cab for large construction equipment. The roof is relatively flat however it is comprised of complex changes in thickness which clearly demonstrate the advantage of robotic chopper gun approach as compared to using numerous preform layers of chopped strand mat. The cost trades for the various preforming methods are summarized to help guide the reader as to preforming method considerations. Finally, these demonstrations all used glass fiber roving. A fourth, exploratory task was added to evaluate the ability to make preforms using Zoltek’s carbon fiber split tow roving. We were able to adapt the chopper gun to make flat preforms for laminate testing, but further development effort would be required to make suitable preforms.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Nuclear Energy Infrastructure Database Fitness and Suitability Review

In 2014, the Deputy Assistant Secretary for Science and Technology Innovation (NE-4) initiated the Nuclear Energy-Infrastructure Management Project by tasking the Nuclear Science User Facilities (NSUF) to create a searchable and interactive database of all pertinent NE supported or related infrastructure. This database will be used for analyses to establish needs, redundancies, efficiencies, distributions, etc. in order to best understand the utility of NE’s infrastructure and inform the content of the infrastructure calls. The NSUF developed the database by utilizing data and policy direction from a wide variety of reports from the Department of Energy, the National Research Council, the International Atomic Energy Agency and various other federal and civilian resources. The NEID contains data on 802 R&D instruments housed in 377 facilities at 84 institutions in the US and abroad. A Database Review Panel (DRP) was formed to review and provide advice on the development, implementation and utilization of the NEID. The panel is comprised of five members with expertise in nuclear energy-associated research. It was intended that they represent the major constituencies associated with nuclear energy research: academia, industry, research reactor, national laboratory, and Department of Energy program management. The Nuclear Energy Infrastructure Database Review Panel concludes that the NSUF has succeeded in creating a capability and infrastructure database that identifies and documents the major nuclear energy research and development capabilities across the DOE complex. The effort to maintain and expand the database will be ongoing. Detailed information on many facilities must be gathered from associated institutions added to complete the database. The data must be validated and kept current to capture facility and instrumentation status as well as to cover new acquisitions and retirements.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Managing Zirconium Chemistry and Phase Compatibility in Combined Process Separations for Minor Actinide Partitioning

In response to the NEUP Program Supporting Fuel Cycle R&D Separations and Waste Forms call DEFOA- 0000799, this report describes the results of an R&D project focusing on streamlining separation processes for advanced fuel cycles. An example of such a process relevant to the U.S. DOE FCR&D program would be one combining the functions of the TRUEX process for partitioning of lanthanides and minor actinides from PUREX(UREX) raffinates with that of the TALSPEAK process for separating transplutonium actinides from fission product lanthanides. A fully-developed PUREX(UREX)/TRUEX/TALSPEAK suite would generate actinides as product(s) for reuse (or transmutation) and fission products as waste. As standalone, consecutive unit-operations, TRUEX and TALSPEAK employ different extractant solutions (solvating (CMPO, octyl(phenyl)-N,Ndiisobutylcarbamoylmethylphosphine oxide) vs. cation exchanging (HDEHP, di-2(ethyl)hexylphosphoric acid) extractants), and distinct aqueous phases (2-4 M HNO 3 vs. concentrated pH 3.5 carboxylic acid buffers containing actinide selective chelating agents). The separate processes may also operate with different phase transfer kinetic constraints. Experience teaches (and it has been demonstrated at the lab scale) that, with proper control, multiple process separation systems can operate successfully. However, it is also recognized that considerable economies of scale could be achieved if multiple operations could be merged into a single process based on a combined extractant solvent. The task of accountability of nuclear materials through the process(es) also becomes more robust with fewer steps, providing that the processes can be accurately modeled. Work is underway in the U.S. and Europe on developing several new options for combined processes (TRUSPEAK, ALSEP, SANEX, GANEX, ExAm are examples). There are unique challenges associated with the operation of such processes, some relating to organic phase chemistry, others arising from the variable composition of the aqueous medium. This project targets in particular two problematic issues in designing combined process systems: managing the chemistry of challenging aqueous species (like Zr 4+ ) and optimizing the composition and properties of combined extractant organic phases.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Biofuels Refining Engineering

The goal of this project is the development of novel catalysts and knowledge of reaction pathways and mechanisms for conversion of biomass-based compounds to fuels that are compatible with oil-based fuels and with acceptable or superior fuel properties. The research scope included both catalysts to convert lignocellulosic biomass-based molecules (from pyrolysis) and vegetable oil-based molecules (i.e., triglycerides and fatty acid methyl esters). This project comprised five technical tasks. Each task is briefly introduced below, and major technical accomplishments summarized. Technical accomplishments were described in greater detail in the quarterly progress reports, and in even more detail in the >50 publications acknowledging this DoE project funding (list of publications and presentations included at the end of this report). The results of this research added greatly to the knowledge base necessary for upgrading of pyrolysis oil to hydrocarbon fuels and chemicals, and for conversion of vegetable oils to fungible diesel fuel. Numerous new catalysts and catalytic reaction systems were developed for upgrading particular compounds or compound families found in the biomass-based pyrolysis oils and vegetable oils. Methods to mitigate catalyst deactivation were investigated, including novel reaction/separation systems. Performance and emission characteristics of biofuels in flames and engines were measured. Importantly, the knowledge developed from this project became the basis for a subsequent collaborative proposal led by our research group, involving researchers from the University of Wisconsin, the University of Pittsburg, and the Idaho National Lab, for the DoE Carbon, Hydrogen and Separations Efficiency (CHASE) program, which was subsequently funded (one of only four projects awarded in the CHASE program). The CHASE project examined novel catalytic processes for lignocellulosic biomass conversion as well as technoeconomic analyses for process options for maximum carbon capture and hydrogen efficiency. Our research approach combined catalyst synthesis, measurements of catalyst activity and selectivity in different reactor systems and conditions, and detailed catalyst characterization to develop fundamental understanding of reaction pathways and the capability to predict product distributions. Nearly all of the candidate catalysts were prepared in-house via standard techniques such as impregnation, co-impregnation, or chemical vapor deposition. Supports were usually purchased, but in some cases coprecipitation was used to simultaneously create the support and active component, which can be advantageous for strong active component-support interactions and for achieving high active component dispersion. In-house synthesis also allowed for studies of the effects on catalyst activity and selectivity of such factors as support porosity, calcination temperature, and reduction/activation conditions. Depending on the physical characteristics of the molecule, catalyst activity measurements were carried out in tubular flow reactors (for vapor phase reactions) or stirred tank reactors (for liquid phase reactions) over a wide range of pressures and temperatures. Reactant and product concentrations were measured using gas chromatography (both on-line and off-line, with TCD, FID, and/or mass spectrometric detection). For promising catalysts, detailed physicochemical characterization was carried out using FTIR, Raman, XPS, and XRD spectroscopies (all available in our laboratories) and TEM spectroscopy (available at OU). Additional methods included temperature programmed techniques (TPD, TPO) and surface area measurements by nitrogen adsorption techniques.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2019

Systematic Technology Evaluation Program for SiC-based BWR Channel Box

Silicon carbide (SiC) –based accident-tolerant fuel (ATF) cladding of light water reactors (LWRs) has become a topic of great interest in nuclear material development since the Fukushima Dai-ichi Nuclear Power Plant accident. Extensive development of SiC cladding has identified benefits of the concept, including its inherent accident resistance and neutronic performance. Advancements achieved during the development of SiC-based ATF cladding have made it attractive for use in accident-tolerant cores of LWRs. In this document, we consider the use of SiC-based materials to replace the zirconium alloy used for the channel boxes of boiling water reactors. Both accident resistance and prevention of the bowing observed in current grades of channel boxes are needs driving the exploration of a new channel box system. To provide a pathway for channel box development, this document lays out (1) a current technology overview, (2) the technology gap, and (3) a systematic technology evaluation plan. The objectives of the technology evaluation plan are to address key feasibility issues revealed by the knowledge gap analysis and to contribute to advancing the technology readiness level. Further development will be required in the technology implementation phase. The technology evaluations include understanding the behavior of channel boxes under both normal and off-normal conditions, identifying potential mitigation strategies for the issues if necessary, and improving channel box performance based on the knowledge obtained. The structure of the technology evaluation plan and each task are shown in Figure S.1. The knowledge gap analysis identified key research areas, including irradiation effects, hydrothermal corrosion, accident behavior, and design and manufacture. These are common issues between SiC-based channel boxes and SiC-based fuel cladding, although technical evaluations specific for the channel box components are required. This document also describes details of the technical feasibility evaluation methods and plans.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2019

Thermodynamics and Kinetics of Phase Transformations in Energy Materials (Final Report)

The primary goal of this program is to develop computational tools and methodology for enabling a shift from empirical trial-and-error driven materials discovery towards data and information technology driven design of materials with targeted functional properties. Both thermodynamic and kinetic factors need to be taken into account when designing new materials. Thermodynamics sets the necessary-but-not-sufficient conditions for the suitability of a particular material in a given application, while the kinetics controls the rates of microscopic processes and hence the performance in energy applications (e.g., power in energy storage, conversion efficiencies in solar cells and thermoelectrics, chemical activity in catalysis). The complexity of these phenomena makes computational design difficult, not least due to the lack of suitable theoretical methods and computational tools. To address these needs, we develop systematic, quantitatively accurate first-principles methods to address two important problems: (i) predict and optimize the thermodynamics of materials over a large composition and structure space, and (ii) model kinetic processes such as mass and heat transport in crystalline solids under non-equilibrium conditions. These tasks are addressed by combining high-throughput computation with automatic construction of accurate lattice models using mathematically rigorous methods of information theory, such as compressive sensing and Bayesian inference.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Deep Learning for Enhancing Fault Tolerant Capabilities of Scientific Workflows

Deep Learning for Enhancing Fault TolerantCapabilities of Scientific WorkflowsAlok Singh, Ilkay AltintasSan Diego Supercomputer Center, UCSDLa Jolla, CA, USA{a1singh, ialtintas}@ucsd.eduMalachi Schram, Nathan TallentPacific Northwestern National LaboratoryRichland, WA, USA{malachi.schram, nathan.tallent}@pnnl.govAbstract-In the history of Computer Science, the act of ‘delegation’ has been the greatest multiplier of society’s problem-solving ability. A scientist working on detecting anomalies in a phenomenon, does not need to re-invent matrix multiplication techniques to solve her problem. Scientific workflows provide ultimate ‘delegation’ mechanism -where a domain scientist can completely forget the specifics of ‘how’ her program will execute on a large cluster in an efficient and cost-effective manner and can instead focus on the mathematical formulation and theoretical robustness of her solution. We present here an approach that directly aims to make the execution of Scientific Workflows more reliable, robust and efficient. We aim that the work presented in this paper will propel the larger effort, from the scientific workflow community, of making scientific workflow execution as simple, efficient and robust as a JOIN operation in a modern database. Specifically, we apply Deep Learning techniques to develop a mechanism that forecasts the final state (success or failure) of a dynamic job in a large-scale particle physics experiment, with minimal data gathering, and as early as possible in job’s life cycle. The key advantage of having a predictive mechanism to identify and anticipate failure-prone jobs is the potential for designing intelligent Fault Tolerance mechanisms to handle anomalous events. We achieve a 14% improvement in computational resources utilization, and an overall classification accuracy of 85% on real tasks executed in a High Energy Physics Computing workflow.To the best of our knowledge, this is the most exhaustive and first of its kind study of neural network architectures in context of a real-dataset profiled from a large-scalescientific workflow.

deep learning↗
DOE OSTI2021

ARM Aerosol Measurement Science Group 2019 Strategic Planning Workshop Report

This report summarizes the results of a U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility workshop held in November 2019 to advance a science-based strategy for ARM’s aerosol measurement program. This was the second such workshop since the Aerosol Measurement Science Group (AMSG) was chartered in 2015 to enhance coordination of ARM observations of aerosols and atmospheric trace gases with the needs of ARM users. The results presented here reflect the AMSG’s focus in recent years on science-based strategies that will contribute to the increased use of ARM data to fulfill its mission of improving process representations and predictability in climate models. Sessions held during the workshop range from interfacing with models through aerosol sampling strategies to calibration protocols and data products. The AMSG workshops have been designed to recommend actions that will enable ARM to evolve and continue to meet its mission. To that end, the AMSG will develop an actionable plan from the recommendations outlined here. Some are well defined and can reasonably be accomplished in the short term. Others are less definite or of a larger scope that calls for a longer-term implementation. Further discussion will be required to develop and prioritize actionable items related to such areas. Task teams comprising the appropriate expertise and perspective from the AMSG and other members of the community will be formed to achieve this outcome. Some particular topics are recognized as high priority, so plans are underway to develop task teams and to hold follow-on discussions to address them. Four areas currently being considered for short, focused discussion are 1) aerosol measurements on the North Slope of Alaska, 2) improving data usability for modeling, 3) strategies for advancing remote sensing, vertical profiling, and distributed measurements of aerosols, and 4) aerosol sampling strategies at existing ARM sites to provide intensive modes of operation to promote data usage for process and modeling studies.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

SymbolNet: neural symbolic regression with adaptive dynamic pruning for compression

Abstract Compact symbolic expressions have been shown to be more efficient than neural network (NN) models in terms of resource consumption and inference speed when implemented on custom hardware such as field-programmable gate arrays (FPGAs), while maintaining comparable accuracy (Tsoi et al 2024 EPJ Web Conf. 295 09036). These capabilities are highly valuable in environments with stringent computational resource constraints, such as high-energy physics experiments at the CERN Large Hadron Collider. However, finding compact expressions for high-dimensional datasets remains challenging due to the inherent limitations of genetic programming (GP), the search algorithm of most symbolic regression (SR) methods. Contrary to GP, the NN approach to SR offers scalability to high-dimensional inputs and leverages gradient methods for faster equation searching. Common ways of constraining expression complexity often involve multistage pruning with fine-tuning, which can result in significant performance loss. In this work, we propose S y m b o l N e t , a NN approach to SR specifically designed as a model compression technique, aimed at enabling low-latency inference for high-dimensional inputs on custom hardware such as FPGAs. This framework allows dynamic pruning of model weights, input features, and mathematical operators in a single training process, where both training loss and expression complexity are optimized simultaneously. We introduce a sparsity regularization term for each pruning type, which can adaptively adjust its strength, leading to convergence at a target sparsity ratio. Unlike most existing SR methods that struggle with datasets containing more than O ( 10 ) inputs, we demonstrate the effectiveness of our model on the LHC jet tagging task (16 inputs), MNIST (784 inputs), and SVHN (3072 inputs).

Tsoi, Ho Fung (ORCID:0000000225502184)↗
DOE OSTI2016

TH-C-BRC-00: Emerging Technologies in SRS/SBRT Delivery

The delivery techniques for SRS/SBRT have been under rapid developments in recent years, which pose new challenges to medical physicists ranging from planning and quality assurance to imaging and motion management. This educational course will provide a general overview of the latest delivery techniques in SRS/SBRT, and discuss the clinical processes to address the challenges of each technique with special emphasis on dedicated gamma-ray based device, robotic x-band linac-based system and conventional C-arm s-band linac-based SRS systems. (1). Gamma-ray based SRS/SRT: This is the gold standard of intracranial SRS. With the advent of precision imaging guidance and frameless patient positioning capabilities, novel stereoscopic CBCT and automatic dose adaption solution are introduced to the Gamma-ray based SRS for the first time. The first North American system has been approved by the US regulatory for patient treatments in the spring of 2016. (2). Robotic SRS/SBRT system: A number of technological milestones have been developed in the past few years, including variable aperture collimator, sequential optimization technique, and the time reduction technique. Recently, a new robotic model allows the option of a multi-leaf collimator. These technological advances have reduced the treatment time and improved dose conformity significantly and could potentially expand the application of radiosurgery for the treatment of targets not previously suitable for robotic SRS/SBRT or fractionated stereotactic radiotherapy. These technological advances have created new demanding mandates on hardware and patient quality assurance (QA) tasks, as well as the need for updating/educating the physicists in the community on these requirements. (3). Conventional Linac based treatments: Modulated arc therapy (MAT) has gained wide popularities in Linac-based treatments in recent years due to its high delivery efficiency and excellent dose conformities. Recently, MAT has been introduced to deliver highly conformal radiosurgery treatments to multiple targets simultaneously via a single isocenter to replace the conventional multi-iso multi-plan treatments. It becomes important to understand the advantages and limitations of this technique, and the pitfalls for implementing this technique in clinical practice. The planning process of single-iso multi-target MAT will be described, and its plan quality and delivery efficiency will be compared with multi-iso plans. The QA process for verifying such complex plans will be illustrated, and pitfalls in imaging and patient set up will be discussed. Overall, this session will focus on the following areas: 1) Update on the emerging technology in current SRS/SBRT delivery. 2) New developments in treatment planning and Quality Assurance program. 3) Imaging guidance and motion management. Learning Objectives: To understand the SRS/SBRT principles and its clinical applications, and gain knowledge on the emerging technologies in SRS/SBRT. To review planning concepts and useful tips in treatment planning. To learn about the imaging guidance procedures and the quality assurance program in SRS/SBRT. National Institutes of Health, Varian Medical System; L. Ren, The presenter is funded by National Institutes of Health and Varian Medical System.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

TH-C-BRC-01: An Overview of Emerging Technologies in SRS/SBRT Delivery

The delivery techniques for SRS/SBRT have been under rapid developments in recent years, which pose new challenges to medical physicists ranging from planning and quality assurance to imaging and motion management. This educational course will provide a general overview of the latest delivery techniques in SRS/SBRT, and discuss the clinical processes to address the challenges of each technique with special emphasis on dedicated gamma-ray based device, robotic x-band linac-based system and conventional C-arm s-band linac-based SRS systems. (1). Gamma-ray based SRS/SRT: This is the gold standard of intracranial SRS. With the advent of precision imaging guidance and frameless patient positioning capabilities, novel stereoscopic CBCT and automatic dose adaption solution are introduced to the Gamma-ray based SRS for the first time. The first North American system has been approved by the US regulatory for patient treatments in the spring of 2016. (2). Robotic SRS/SBRT system: A number of technological milestones have been developed in the past few years, including variable aperture collimator, sequential optimization technique, and the time reduction technique. Recently, a new robotic model allows the option of a multi-leaf collimator. These technological advances have reduced the treatment time and improved dose conformity significantly and could potentially expand the application of radiosurgery for the treatment of targets not previously suitable for robotic SRS/SBRT or fractionated stereotactic radiotherapy. These technological advances have created new demanding mandates on hardware and patient quality assurance (QA) tasks, as well as the need for updating/educating the physicists in the community on these requirements. (3). Conventional Linac based treatments: Modulated arc therapy (MAT) has gained wide popularities in Linac-based treatments in recent years due to its high delivery efficiency and excellent dose conformities. Recently, MAT has been introduced to deliver highly conformal radiosurgery treatments to multiple targets simultaneously via a single isocenter to replace the conventional multi-iso multi-plan treatments. It becomes important to understand the advantages and limitations of this technique, and the pitfalls for implementing this technique in clinical practice. The planning process of single-iso multi-target MAT will be described, and its plan quality and delivery efficiency will be compared with multi-iso plans. The QA process for verifying such complex plans will be illustrated, and pitfalls in imaging and patient set up will be discussed. Overall, this session will focus on the following areas: 1) Update on the emerging technology in current SRS/SBRT delivery. 2) New developments in treatment planning and Quality Assurance program. 3) Imaging guidance and motion management. Learning Objectives: To understand the SRS/SBRT principles and its clinical applications, and gain knowledge on the emerging technologies in SRS/SBRT. To review planning concepts and useful tips in treatment planning. To learn about the imaging guidance procedures and the quality assurance program in SRS/SBRT. National Institutes of Health, Varian Medical System; L. Ren, The presenter is funded by National Institutes of Health and Varian Medical System.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

TH-C-BRC-02: A Review of Emerging Technologies in Robotic SRS/SBRT Delivery

The delivery techniques for SRS/SBRT have been under rapid developments in recent years, which pose new challenges to medical physicists ranging from planning and quality assurance to imaging and motion management. This educational course will provide a general overview of the latest delivery techniques in SRS/SBRT, and discuss the clinical processes to address the challenges of each technique with special emphasis on dedicated gamma-ray based device, robotic x-band linac-based system and conventional C-arm s-band linac-based SRS systems. (1). Gamma-ray based SRS/SRT: This is the gold standard of intracranial SRS. With the advent of precision imaging guidance and frameless patient positioning capabilities, novel stereoscopic CBCT and automatic dose adaption solution are introduced to the Gamma-ray based SRS for the first time. The first North American system has been approved by the US regulatory for patient treatments in the spring of 2016. (2). Robotic SRS/SBRT system: A number of technological milestones have been developed in the past few years, including variable aperture collimator, sequential optimization technique, and the time reduction technique. Recently, a new robotic model allows the option of a multi-leaf collimator. These technological advances have reduced the treatment time and improved dose conformity significantly and could potentially expand the application of radiosurgery for the treatment of targets not previously suitable for robotic SRS/SBRT or fractionated stereotactic radiotherapy. These technological advances have created new demanding mandates on hardware and patient quality assurance (QA) tasks, as well as the need for updating/educating the physicists in the community on these requirements. (3). Conventional Linac based treatments: Modulated arc therapy (MAT) has gained wide popularities in Linac-based treatments in recent years due to its high delivery efficiency and excellent dose conformities. Recently, MAT has been introduced to deliver highly conformal radiosurgery treatments to multiple targets simultaneously via a single isocenter to replace the conventional multi-iso multi-plan treatments. It becomes important to understand the advantages and limitations of this technique, and the pitfalls for implementing this technique in clinical practice. The planning process of single-iso multi-target MAT will be described, and its plan quality and delivery efficiency will be compared with multi-iso plans. The QA process for verifying such complex plans will be illustrated, and pitfalls in imaging and patient set up will be discussed. Overall, this session will focus on the following areas: 1) Update on the emerging technology in current SRS/SBRT delivery. 2) New developments in treatment planning and Quality Assurance program. 3) Imaging guidance and motion management. Learning Objectives: To understand the SRS/SBRT principles and its clinical applications, and gain knowledge on the emerging technologies in SRS/SBRT. To review planning concepts and useful tips in treatment planning. To learn about the imaging guidance procedures and the quality assurance program in SRS/SBRT. National Institutes of Health, Varian Medical System; L. Ren, The presenter is funded by National Institutes of Health and Varian Medical System.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

TH-C-BRC-03: Emerging Linac Based SRS/SBRT Technologies with Modulated Arc Delivery

The delivery techniques for SRS/SBRT have been under rapid developments in recent years, which pose new challenges to medical physicists ranging from planning and quality assurance to imaging and motion management. This educational course will provide a general overview of the latest delivery techniques in SRS/SBRT, and discuss the clinical processes to address the challenges of each technique with special emphasis on dedicated gamma-ray based device, robotic x-band linac-based system and conventional C-arm s-band linac-based SRS systems. (1). Gamma-ray based SRS/SRT: This is the gold standard of intracranial SRS. With the advent of precision imaging guidance and frameless patient positioning capabilities, novel stereoscopic CBCT and automatic dose adaption solution are introduced to the Gamma-ray based SRS for the first time. The first North American system has been approved by the US regulatory for patient treatments in the spring of 2016. (2). Robotic SRS/SBRT system: A number of technological milestones have been developed in the past few years, including variable aperture collimator, sequential optimization technique, and the time reduction technique. Recently, a new robotic model allows the option of a multi-leaf collimator. These technological advances have reduced the treatment time and improved dose conformity significantly and could potentially expand the application of radiosurgery for the treatment of targets not previously suitable for robotic SRS/SBRT or fractionated stereotactic radiotherapy. These technological advances have created new demanding mandates on hardware and patient quality assurance (QA) tasks, as well as the need for updating/educating the physicists in the community on these requirements. (3). Conventional Linac based treatments: Modulated arc therapy (MAT) has gained wide popularities in Linac-based treatments in recent years due to its high delivery efficiency and excellent dose conformities. Recently, MAT has been introduced to deliver highly conformal radiosurgery treatments to multiple targets simultaneously via a single isocenter to replace the conventional multi-iso multi-plan treatments. It becomes important to understand the advantages and limitations of this technique, and the pitfalls for implementing this technique in clinical practice. The planning process of single-iso multi-target MAT will be described, and its plan quality and delivery efficiency will be compared with multi-iso plans. The QA process for verifying such complex plans will be illustrated, and pitfalls in imaging and patient set up will be discussed. Overall, this session will focus on the following areas: 1) Update on the emerging technology in current SRS/SBRT delivery. 2) New developments in treatment planning and Quality Assurance program. 3) Imaging guidance and motion management. Learning Objectives: To understand the SRS/SBRT principles and its clinical applications, and gain knowledge on the emerging technologies in SRS/SBRT. To review planning concepts and useful tips in treatment planning. To learn about the imaging guidance procedures and the quality assurance program in SRS/SBRT. National Institutes of Health, Varian Medical System; L. Ren, The presenter is funded by National Institutes of Health and Varian Medical System.

60 APPLIED LIFE SCIENCES↗