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The goals for the work were to create and probe matter under extreme conditions using ultrafast optical and x-ray techniques. We measured electronic structure and plasma properties of warm and hot dense matter, and validate modeling and simulation codes, with a goal of understanding the static and dynamic properties of such materials.
The objective of this proposal is to demonstrate the capability to predict the evolution of microstructure and properties of structural materials in-reactor and at high doses, using ion irradiation as a surrogate for reactor irradiations. “Properties” includes both physical properties (irradiated microstructure) and the mechanical properties of the material. Demonstration of the capability to predict properties has two components. One is ion irradiation of a set of alloys to yield an irradiated microstructure and corresponding mechanical behavior that are substantially the same as results from neutron exposure in the appropriate reactor environment. Second is the capability to predict the irradiated microstructure and corresponding mechanical behavior on the basis of improved models, validated against both ion and reactor irradiations and verified against ion irradiations. Taken together, achievement of these objectives will yield an enhanced capability for simulating the behavior of materials in reactor irradiations.
This report documents work performed under the Spent Fuel and Waste Disposition for the US Department of Energy (DOE) Office of Nuclear Energy (NE) Spent Fuel and Waste Science and Technology program. This work was performed to fulfill the Level 2 Milestone M2SF-17OR010201021, “Documentation of Non-destructive Tests on Sister Pins,” within work package SF-17OR01020102. The High Burnup Spent Fuel Data Project, sponsored by DOE-NE, is focused on understanding the effects of long-term storage and transportation on high burnup (HBU) (>45 gigawatt days per metric ton uranium) light water reactor fuel. The goals of the project are to “provide confirmatory data for model validation and potential improvement, provide input to future spent nuclear fuel (SNF) dry storage cask design, support license renewals and new licenses for Independent Spent Fuel Storage Installations (ISFSIs), and support transportation licensing for high burnup SNF". In support of project goals, 25 sister rods were removed from fuel assemblies at the North Anna Power Station. Nine rods were removed from the project assemblies, and 16 rods were removed from similar HBU assemblies. The 25 sister rods were shipped to Oak Ridge National Laboratory (ORNL) Irradiated Fuels Examination Laboratory (IFEL) in early 2016 for detailed nondestructive examination (NDE) and destructive examination (DE). The detailed examinations will provide essential information on the physical state of the HBU rods and the fuel contained in the rods prior to loading, drying, and long-term dry storage. Similar tests will be performed at the end of the long-term storage period to identify any changes in the fuel rods’ properties during the dry storage period.
The computational bias of criticality safety computer codes must be established through the validation of the codes to critical experiments. A large collection of suitable experiments has been vetted by the International Criticality Safety Benchmark Evaluation Project (ICSBEP) and made available in the International Handbook of Evaluated Criticality Safety Benchmark Experiments (ICSBEP Handbook). More than 600 cases from this handbook ha ve been prepared and reviewed within the Verified, Archived Library of Inputs and Data (VALID) , which is maintained by the Reactor and Nuclear Systems Division at Oak Ridge National Laboratory. The performance of the KENO V.a and KENO-VI Monte Carlo codes within the SCALE 6.2.2 code system is assessed using the VALID models of benchmark experiments. A range of nuclear cross section libraries based on both ENDF/B-VII.1 and ENDF/B-VII.0 in both multigroup (MG) and continuous energy (CE) formats is considered. The TSUNAMI tools for sensitivity and uncertainty analysis are used to examine some systems further to try to identify potential causes of unexpected results.
This report provides guidance on how to adjust temperature measurements from mineral-insulated, metal-sheathed (MIMS) thermocouples (TCs) mounted on metal plates to correct for slow transient response. This information is needed so that more accurate transient temperature measurements can be made. These more accurate temperature measurements are of benefit for both qualification of hardware and as data sets for model validation. The approach was to use a relatively simple first order adjustment to the MIMS TC reading, as compared to a more accurate metal plate temperature measurement. MIMS TCs are used to improve reliability. Results from four data sets were analyzed to determine the time constraint; an overall average of 5.0 s was obtained.
Sierra/SD provides a massively parallel implementation of structural dynamics finite element analysis, required for high fidelity, validated models used in modal, vibration, static and shock analysis of weapons systems. This document provides a users guide to the input for Sierra/SD. Details of input specifications for the different solution types, output options, element types and parameters are included. The appendices contain detailed examples, and instructions for running the software on parallel platforms.
In this project, we researched new techniques for detecting hidden networks of individuals and institutions by introducing the use of temporal correlations among behaviors, leveraging both information sources and metadata. We validated the algorithms using the Wikipedia edit history. The rapid increase in crowd-sourced applications like Wikipedia is providing a rich set of data with both a record of behaviors and a set of direct interactions among individuals. Data sets with network ground truth are needed to develop and validate models, before applying them to national security settings where content and meta-data alone are available.
Photovoltaic (PV) systems using microinverters are becoming increasingly popular in the residential system market, as such systems offer several advantages over PV systems using central inverters. PV modules with integrated microinverters, termed AC modules, are emerging to fill this market space. Existing test procedures and performance models designed for separate DC and AC components are unusable for AC modules because these do not allow ready access to the intermediate DC bus. Sandia National Laboratories' Photovoltaics and Distributed Systems department has developed a set of procedures to test, characterize, and model PV modules with integrated microinverters. The resulting empirical model is able to predict the output AC power of with RMS error of 1-2%. This document describes these procedures and provides the results of model validation efforts.
To address a variety of difficulties surrounding the use of finite element analysis (FEA) in product development at Sandia, this research explored a 'designerly' insertion of FEA into the design-build-test product development cycle. Designerly FEA is characterized by the use of simplified FEA models, designer-friendly FEA software, an FEA analyst embedded in the product design team, relative comparisons of design options, and a deliberate leveraging of routine prototype testing to collect model validation data. Two case study projects were used to explore the impact of this approach on the product development teams' thinking and perceptions of FEA. The case study data was collected using mixed methods and analyzed using a theory-building approach. The results were synthesized into a framework describing how the use of FEA to build confidence in a product design is related to the process by which product development teams gain or lose confidence in FEA itself. The implications may extend to other organizations that desire to increase the impact of simulation technologies in their product development process.
An analytical expression of the low-frequency quadrupole impedance for undulators and wigglers is derived and benchmarked against beam-based impedance measurements done at the 3GeV NSLS-II storage ring. The adopted theoretical model, valid for an arbitrary number of electromagnetic layers with parallel geometry, allows to calculate the quadrupole impedance for arbitrary values of the magnetic permeability $μ_r$. In the comparison of the analytical results with the measurements for variable magnet gaps, two limit cases of the permeability have been studied: the case of perfect magnets ($μ_r$ → $\infty$), and the case in which the magnets are fully saturated ($μ_r$ = 1).
Shen was the PI for DOE project entitled Scale-Aware, Improved Hydrological and Biogeochemical Simulations of the Amazon Under a Changing Climate (contract DE-SC0010620; PI: Chaopeng Shen; co-PI, John Melack, William Riley, $976,000, 2013-2018). Under this project, the group has made substantial progress in (a) scientific advancement: (b) model and software engineering development; (c) aided parallel DoE project; (d) generating datasets; and (e) graduate and postdoc education that are useful global data fusion and model validation; and (f) participated and presented in several conferences. In summary, we have published 15 peer-reviewed papers (citations bolded below) and numerous conference presentations. One more paper is still under review. Our software progress has been shared with the wider community.
Sierra/SD provides a massively parallel implementation of structural dynamics finite element analysis, required for high fidelity, validated models used in modal, vibration, static and shock analysis of structural systems. This manual describes the theory behind many of the constructs in Sierra/SD. For a more detailed description of how to use Sierra/SD , we refer the reader to Sierra/SD, User's Notes . Many of the constructs in Sierra/SD are pulled directly from published material. Where possible, these materials are referenced herein. However, certain functions in Sierra/SD are specific to our implementation. We try to be far more complete in those areas. The theory manual was developed from several sources including general notes, a programmer_notes manual, the user's notes and of course the material in the open literature.
Improvements in time-stepping schemes can provide substantial improvements in the throughput of global ocean-climate models, but is challenging due to large variations in time scales in the dynamics and spatial scales in the global, variable resolution mesh. Two funded projects aim to speed up the Model for Prediction Across Scales-Ocean (MPAS-Ocean). The first will add a variable-timestepping formulation to MPAS-Ocean, which is a critical step towards running efficiently on global variable-resolution meshes with regional and coastal refinement. The second optimizes the barotropic (depth-integrated) mode, which is currently a performance bottleneck at high core counts. The proposed compute time will be used for extensive model validation and parameter studies for both methods.
Recent improvements in the radiation effects science capability at Sandia have achieved the following: Record gamma-ray outputs at HERMES enable qualification for Life Extension Programs (LEPs) and evaluation of electromagnetic pulse (EMP) effects on electric grid elements; Completed blind comparison for model validation of cavity system generated EMP in advanced computer simulations; For the first time, new diagnostics provide a high resolution photon energy spectrum on Z (Grand Challenge LDRD); ACRR completed record number of operations, two years in a row, to support design and qualification; Installed the nation’s largest GHz electromagnetic test chamber for design and qualification.
This project investigates the behavior of a venting feature on a hermetically sealed volume under abnormal thermal environments. A pressure profile is used to simulate internal pressure build up due to thermal decomposition of foam caused by temperatures approaching 800K. For the purposes of his scoping study a small can composed of 304L stainless steel is used to emulate the problem at hand and simplify the model. The venting feature can be described as an elliptical thinned area with X-like scoring marks on the circumferential surface of the can where the highest stresses are located without the feature. The feature variables include elliptical size, depth, and quantity to optimize the venting feature geometry to vent at a desired pressure range. Cubit, SIERRA: Solid Mechanics, and Ensight modeling programs are used to simulate and analyze several iterations of this feature to determine the most optimal geometry. The model indicates through the simulations that the feature does in fact vent in a predictable manner and can be used in a variety of pressure vessel applications where uncontrolled over pressurizations are undesirable. Future work includes model validation tests, looking at different geometries, and using a more accurate failure criterion.
Sierra/SD provides a massively parallel implementation of structural dynamics finite element analysis, required for high fidelity, validated models used in modal, vibration, static and shock analysis of weapons systems. This document provides a users guide to the input for Sierra/SD. Details of input specifications for the different solution types, output options, element types and parameters are included. The appendices contain detailed examples, and instructions for running the software on parallel platforms.
The following is a description of modeling the constitutive behavior of the transforming and non-transforming 316 stainless steel measured in-situ at APS. Details of the elasto-viscoplastic self-consistent (EVPSC) polycrystal deformation model are described in the literature and only the salient information is given here. The EVPSC model is a general rate-sensitive self-consistent polycrystal plasticity model valid at arbitrary large deformations. The homogenizing method used is the self-consistent approach, originally proposed by Kröner, assuming that each grain is an ellipsoidal inclusion embedded in an infinite homogeneous equivalent medium (HEM), where the interaction is determined using Eshelby's solution. The hardening behavior is described by a Voce type strain hardening law, and the phase transformation uses a strain energy criterion for choosing a single daughter grain for each parent grain that reaches a critical value of the Von Mises equivalent strain. The orientation relationship between parent and daughter grains is determined based upon a rotation matrix that preserves an invariant line between the parent and daughter. The evolution law for the growth of the martensite phase is based on an empirical accumulated shear strain law proposed by Olson and Cohen. The single crystal elastic constants for the austenite phase are as reported for 316 stainless steel and the single crystal elastic constants of the martensite are taken from hardened SAE 1050 plain-carbon steel.
On September 30, 2019 LANL successfully performed the initial test of a 155 mm cannon. This gun will be used in experiments where fragments are launched into targets containing energetic materials and the response of the target is measured in order to help validate models of the materials. The size of the cannon allows more flexibility in the choice of fragment and target geometries. Over the past three years, LANL employees have worked with many DoD sites including Sierra Army Depot, Yuma Proving Ground, and Picatinny Arsenal as well as commercial companies including St. Marks Powder and Mandus Group arranging the loan and refurbishment of three M198 155 mm howitzers. This work has been supported by the NNSA/NA-82 Standoff Disablement Program in conjunction with the DOE/DoD Joint Munitions Program.