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DOE OSTI2016

Verification and Validation of a Coordinate Transformation Method in Axisymmetric Transient Magnetics.

We present a verification and validation analysis of a coordinate-transformation-based numerical solution method for the two-dimensional axisymmetric magnetic diffusion equation, implemented in the finite-element simulation code ALEGRA. The transformation, suggested by Melissen and Simkin, yields an equation set perfectly suited for linear finite elements and for problems with large jumps in material conductivity near the axis. The verification analysis examines transient magnetic diffusion in a rod or wire in a very low conductivity background by first deriving an approximate analytic solution using perturbation theory. This approach for generating a reference solution is shown to be not fully satisfactory. A specialized approach for manufacturing an exact solution is then used to demonstrate second-order convergence under spatial refinement and tem- poral refinement. For this new implementation, a significant improvement relative to previously available formulations is observed. Benefits in accuracy for computed current density and Joule heating are also demonstrated. The validation analysis examines the circuit-driven explosion of a copper wire using resistive magnetohydrodynamics modeling, in comparison to experimental tests. The new implementation matches the accuracy of the existing formulation, with both formulations capturing the experimental burst time and action to within approximately 2%.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

STAR-CCM+ Verification and Validation Plan

The commercial Computational Fluid Dynamics (CFD) code STAR-CCM+ provides general purpose finite volume method solutions for fluid dynamics and energy transport. This document defines plans for verification and validation (V&V) of the base code and models implemented within the code by the Consortium for Advanced Simulation of Light water reactors (CASL). The software quality assurance activities described herein are port of the overall software life cycle defined in the CASL Software Quality Assurance (SQA) Plan [Sieger, 2015]. STAR-CCM+ serves as the principal foundation for development of an advanced predictive multi-phase boiling simulation capability within CASL. The CASL Thermal Hydraulics Methods (THM) team develops advanced closure models required to describe the subgrid-resolution behavior of secondary fluids or fluid phases in multiphase boiling flows within the Eulerian-Eulerian framework of the code. These include wall heat partitioning models that describe the formation of vapor on the surface and the forces the define bubble/droplet dynamic motion. The CASL models are implemented as user coding or field functions within the general framework of the code. This report defines procedures and requirements for V&V of the multi-phase CFD capability developed by CASL THM. Results of V&V evaluations will be documented in a separate STAR-CCM+ V&V assessment report. This report is expected to be a living document and will be updated as additional validation cases are identified and adopted as part of the CASL THM V&V suite.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2015

CTF Void Drift Validation Study

This milestone report is a summary of work performed in support of expansion of the validation and verification (V&V) matrix for the thermal-hydraulic subchannel code, CTF. The focus of this study is on validating the void drift modeling capabilities of CTF and verifying the supporting models that impact the void drift phenomenon. CTF uses a simple turbulent-diffusion approximation to model lateral cross-flow due to turbulent mixing and void drift. The void drift component of the model is based on the Lahey and Moody model. The models are a function of two-phase mass, momentum, and energy distribution in the system; therefore, it is necessary to correctly model the ow distribution in rod bundle geometry as a first step to correctly calculating the void distribution due to void drift.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Validation of CTF Droplet Entrainment and Annular/Mist Closure Models using Riso Steam/Water Experiments

This report summarizes the work done to validate the droplet entrainment and de-entrainment models as well as two-phase closure models in the CTF code by comparison with experimental data obtained at Riso National Laboratory. The Riso data included a series of over 250 steam/water experiments that were performed in both tube and annulus geometries over a range of various pressures and outlet qualities. Experimental conditions were set so that the majority of cases were in the annular/mist ow regime. Measurements included liquid lm ow rate, droplet ow rate, lm thickness, and two-phase pressure drop. CTF was used to model 180 of the tubular geometry cases, matching experimental geometry, outlet pressure, and outlet ow quality to experimental values. CTF results were compared to the experimental data at the outlet of the test section in terms of vapor and entrained liquid ow fractions, pressure drop per unit length, and liquid lm thickness. The entire process of generating CTF input decks, running cases, extracting data, and generating comparison plots was scripted using Python and Matplotlib for a completely automated validation process. All test cases and scripting tools have been committed to the COBRA-TF master repository and selected cases have been added to the continuous testing system to serve as regression tests. The dierences between the CTF- and experimentally-calculated ow fraction values were con- sistent with previous calculations by Wurtz, who applied the same entrainment correlation to the same data. It has been found that CTF's entrainment/de-entrainment predictive capability in the annular/mist ow regime for this particular facility is comparable to the licensed industry code, COBRAG. While lm and droplet predictions are generally good, it has been found that accuracy is diminished at lower ow qualities. This nding is consistent with the noted deciencies in the Wurtz entrainment model employed by CTF. The CTF predicted two-phase pressure drop in the annular/mist ow regime has been found to be highly inaccurate, exhibiting a clear bias with respect to the experimental data. This inaccuracy led to an investigation that revealed deciencies in the implementation of the annular/mist interfacial friction model, which should be investigated further in the future. Looking to published COBRAG results for this same facility reveal it exhibits no bias with regard to experimental pressure drop results. In addition to the problems with pressure drop prediction, the lm thickness was also signicantly under-predicted by CTF compared to both experimental data and Wurtz's analytical calculations. Film thickness is calculated using a simple geometric relationship and lm void fraction in CTF, which is dependent on slip ratio and interfacial friction. It is possible that the issues aecting the pressure drop and lm void prediction are related.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

Advanced Reactors-Intermediate Heat Exchanger (IHX) Coupling: Theoretical Modeling and Experimental Validation

The overall goal of the research project was to model the behavior of the advanced reactorintermediate heat exchange system and to develop advanced control techniques for off-normal conditions. The specific objectives defined for the project were: 1. To develop the steady-state thermal hydraulic design of the intermediate heat exchanger (IHX); 2. To develop mathematical models to describe the advanced nuclear reactor-IHX-chemical process/power generation coupling during normal and off-normal operations, and to simulate models using multiphysics software; 3. To develop control strategies using genetic algorithm or neural network techniques and couple these techniques with the multiphysics software; 4. To validate the models experimentally The project objectives were accomplished by defining and executing four different tasks corresponding to these specific objectives. The first task involved selection of IHX candidates and developing steady state designs for those. The second task involved modeling of the transient and offnormal operation of the reactor-IHX system. The subsequent task dealt with the development of control strategies and involved algorithm development and simulation. The last task involved experimental validation of the thermal hydraulic performances of the two prototype heat exchangers designed and fabricated for the project at steady state and transient conditions to simulate the coupling of the reactor- IHX-process plant system. The experimental work utilized the two test facilities at The Ohio State University (OSU) including one existing High-Temperature Helium Test Facility (HTHF) and the newly developed high-temperature molten salt facility.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2017

Validation of PV-RPM Code in the System Advisor Model.

This paper describes efforts made by Sandia National Laboratories (SNL) and the National Renewable Energy Laboratory (NREL) to validate the SNL developed PV Reliability Performance Model (PV - RPM) algorithm as implemented in the NREL System Advisor Model (SAM). The PV - RPM model is a library of functions that estimates component failure and repair in a photovoltaic system over a desired simulation period. The failure and repair distributions in this paper are probabilistic representations of component failure and repair based on data collected by SNL for a PV power plant operating in Arizona. The validation effort focuses on whether the failure and repair dist ributions used in the SAM implementation result in estimated failures that match the expected failures developed in the proof - of - concept implementation. Results indicate that the SAM implementation of PV - RPM provides the same results as the proof - of - concep t implementation, indicating the algorithms were reproduced successfully.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

Summary of BISON Development and Validation Activities - NEAMS FY16 Report

This summary report contains an overview of work performed under the work package en- titled “FY2016 NEAMS INL-Engineering Scale Fuel Performance (BISON)” A first chapter identifies the specific FY-16 milestones, providing a basic description of the associated work and references to related detailed documentation. Where applicable, a representative technical result is provided. A second chapter summarizes major additional accomplishments, which in- clude: 1) publication of a journal article on solution verification and validation of BISON for LWR fuel, 2) publication of a journal article on 3D Missing Pellet Surface (MPS) analysis of BWR fuel, 3) use of BISON to design a unique 3D MPS validation experiment for future in- stallation in the Halden research reactor, 4) participation in an OECD benchmark on Pellet Clad Mechanical Interaction (PCMI), 5) participation in an OECD benchmark on Reactivity Insertion Accident (RIA) analysis, 6) participation in an OECD activity on uncertainity quantification and sensitivity analysis in nuclear fuel modeling and 7) major improvements to BISON’s fission gas behavior models. A final chapter outlines FY-17 future work.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Fast Running Urban Dispersion Model for Radiological Dispersal Device (RDD) Releases: Model Description and Validation

Aeolus is an efficient three-dimensional computational fluid dynamics code based on finite volume method developed for predicting transport and dispersion of contaminants in a complex urban area. It solves the time dependent incompressible Navier-Stokes equation on a regular Cartesian staggered grid using a fractional step method. It also solves a scalar transport equation for temperature and using the Boussinesq approximation. The model also includes a Lagrangian dispersion model for predicting the transport and dispersion of atmospheric contaminants. The model can be run in an efficient Reynolds Average Navier-Stokes (RANS) mode with a run time of several minutes, or a more detailed Large Eddy Simulation (LES) mode with run time of hours for a typical simulation. This report describes the model components, including details on the physics models used in the code, as well as several model validation efforts. Aeolus wind and dispersion predictions are compared to field data from the Joint Urban Field Trials 2003 conducted in Oklahoma City (Allwine et al 2004) including both continuous and instantaneous releases. Newly implemented Aeolus capabilities include a decay chain model and an explosive Radiological Dispersal Device (RDD) source term; these capabilities are described. Aeolus predictions using the buoyant explosive RDD source are validated against two experimental data sets: the Green Field explosive cloud rise experiments conducted in Israel (Sharon et al 2012) and the Full-Scale RDD Field Trials conducted in Canada (Green et al 2016).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

CTF (Subchannel) Calculations and Validation L3:VVI.H2L.P15.01

The goal of the Verification and Validation Implementation (VVI) High to Low (Hi2Lo) process is utilizing a validated model in a high resolution code to generate synthetic data for improvement of the same model in a lower resolution code. This process is useful in circumstances where experimental data does not exist or it is not sufficient in quantity or resolution. Data from the high-fidelity code is treated as calibration data (with appropriate uncertainties and error bounds) which can be used to train parameters that affect solution accuracy in the lower-fidelity code model, thereby reducing uncertainty. This milestone presents a demonstration of the Hi2Lo process derived in the VVI focus area. The majority of the work performed herein describes the steps of the low-fidelity code used in the process with references to the work detailed in the companion high-fidelity code milestone (Reference 1). The CASL low-fidelity code used to perform this work was Cobra Thermal Fluid (CTF) and the high-fidelity code was STAR-CCM+ (STAR). The master branch version of CTF (pulled May 5, 2017 – Reference 2) was utilized for all CTF analyses performed as part of this milestone. The statistical and VVUQ components of the Hi2Lo framework were performed using Dakota version 6.6 (release date May 15, 2017 – Reference 3). Experimental data from Westinghouse Electric Company (WEC – Reference 4) was used throughout the demonstrated process to compare with the high-fidelity STAR results. A CTF parameter called Beta was chosen as the calibration parameter for this work. By default, Beta is defined as a constant mixing coefficient in CTF and is essentially a tuning parameter for mixing between subchannels. Since CTF does not have turbulence models like STAR, Beta is the parameter that performs the most similar function to the turbulence models in STAR. The purpose of the work performed in this milestone is to tune Beta to an optimal value that brings the CTF results closer to those measured in the WEC experiments.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Creation of System Validation Platform

SNL and SunSpec were to create a System Validation Platform to verify the functionality of DERs with advanced grid functionality and utility communication capabilities. The Validation Platform software was to ensure DERs are compatible with new grid interconnection requirements for these advanced functions by communicating to equipment under test, data acquisition software, and test equipment.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

Complex Systems Models and Their Applications: Towards a New Science of Verification, Validation & Uncertainty Quantification

This report contains the written footprint of a Sandia-hosted workshop held in Albuquerque, New Mexico, June 22-23, 2016 on “Complex Systems Models and Their Applications: Towards a New Science of Verification, Validation and Uncertainty Quantification,” as well as of pre-work that fed into the workshop. The workshop’s intent was to explore and begin articulating research opportunities at the intersection between two important Sandia communities: the complex systems (CS) modeling community, and the verification, validation and uncertainty quantification (VVUQ) community The overarching research opportunity (and challenge) that we ultimately hope to address is: how can we quantify the credibility of knowledge gained from complex systems models, knowledge that is often incomplete and interim, but will nonetheless be used, sometimes in real-time, by decision makers?

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2018

Computational Design and Discovery of Ni-Based Alloys and Coatings: Thermodynamic Approaches Validated by Experiments

This project developed computational tools that can complement and support experimental efforts in order to enable discovery and more efficient development of Ni-base structural materials and coatings. The project goal was reached through an integrated computation-predictive and experimental-validation approach, including first-principles calculations, thermodynamic CALPHAD (CALculation of PHAse Diagram), and experimental investigations on compositions relevant to Ni-base superalloys and coatings in terms of oxide layer growth and microstructure stabilities. The developed description included composition ranges typical for coating alloys and, hence, allow for prediction of thermodynamic properties for these material systems. The calculation of phase compositions, phase fraction, and phase stabilities, which are directly related to properties such as ductility and strength, was a valuable contribution, along with the collection of computational tools that are required to meet the increasing demands for strong, ductile and environmentally-protective coatings. Specifically, a suitable thermodynamic description for the Ni-Al-Cr-Co-Si-Hf-Y system was developed for bulk alloy and coating compositions. Experiments were performed to validate and refine the thermodynamics from the CALPHAD modeling approach. Additionally, alloys produced using predictions from the current computational models were studied in terms of their oxidation performance. Finally, results obtained from experiments aided in the development of a thermodynamic modeling automation tool called ESPEI/pycalphad - for more rapid discovery and development of new materials.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Validation Study of the Spacecraft Background Activation using RHESSI Data

This document serves as a brief writeup of the work done to validate CINDER2008 and the Activation Analysis Tools in the Activation in Accelerator Radiation Environments (AARE) distribution that are used to calculate the activation of spacecraft material while in orbit [1{3]. The validation study involves replicating the decay gamma spectrum as observed onboard the RHESSI spacecraft in the high-purity germanium (HPGe) detectors after crossing the South Atlantic Anomaly (SAA) [4]. The tools involved are a suite of Python scripts, the transmutation code CINDER2008 accompanied with a suite of scripts distributed with AARE,MCNPX, and MCNP6.2 [2,5{7]. Figure 1 shows the gamma ray spectrum this study replicates as the spectrum designated \Difference".

42 ENGINEERING↗
DOE OSTI2018

Development and Rigorous Validation of Modules for Predicting Organic Aerosol CCN Activity from Molecular Properties

The indirect interaction of anthropogenic aerosols with clouds (aerosol indirect forcing) represents one of the main uncertainties in climate projections, and reducing this uncertainty requires improved understanding of the aerosol life cycle, including atmospheric aging and the ability to nucleate cloud droplets or crystals. A key parameter that links the chemical properties of aerosol to its nucleating properties, and ultimately to aerosol indirect forcing, is its hygroscopicity (ability to uptake water). One way to compare and systematize the ability of various chemical compounds or particle types to nucleate cloud drops is via the hygroscopicity parameter κ, which can be used directly in global models to simulate aerosol indirect forcing. In this project we further investigated the relationships between the chemical composition of organic aerosol particles, which are known to be important components of atmospheric particulate matter, and their ability to serve as cloud condensation nuclei (CCN). In particular, we isolated the role of viscosity on κ by applying methods similar to those we used previously in our DOE/ASR research. Our motivation for the focus on viscosity was through its link to particle phase state. Particle phase affects water uptake on timescales relevant to the laboratory and also likely relevant to atmospheric processes, with reduced apparent hygroscopicities for semisolid and solid particles, compared with liquid particles. Water uptake itself affects viscosity, an important feedback that we explored in this project. The objectives of the project were as follows: (1) measure the effects of molecular structure, temperature, and relative humidity on the viscosity of organic aerosol formed via controlled laboratory experiments, (2) measure the effects of organic aerosol viscosity on water uptake and CCN activity above and below water saturation, (3) further develop the κ parameterization of organic aerosol hygroscopicity to include viscosity/phase, and (4) experimentally validate the κ parameterization for organic aerosol with chemical composition ranging from relatively simple to complex. It was proposed that particle viscosity exerts a kinetic control on equilibrium water uptake. High viscosity was expected to delay water uptake based on diffusional limitations. This would manifest itself in reduced observed CCN activity or κ. Understanding the interplay between water content and viscosity (composition control on particle viscosity) and between viscosity and equilibrium water content (diffusional control on water uptake) were the overall science objectives of this grant. Targeted experiments were carried out to test the kinetic control hypothesis. These experiments included studies that explicitly measured the equilibration time scale of water uptake, and experiments that tested the role of viscous particle coatings on the observed CCN activity. From the combined work, it is concluded that mass transfer limitations by glassy organic particles are unlikely to affect cloud droplet activation near laboratory temperatures. This implies that viscosity does not need to be included in parameterizations that link particle chemical composition and κ. A parameterization to predict κ through the UNIFAC group contribution method was developed with previous ASR funding. As planned, this computational module was further developed and validated here through targeted laboratory studies. The computational module has been made available as free software under the GNU public license. A database of κ-values to aid model development has been compiled and is available online via an open access model. In conducting this work, significant effort was made to understand how aerosol composition, including the associated aerosol water content, affects viscosity. This included a study detailing the influence of functional group composition on organic aerosol viscosity. We identified a strong link between volatility and viscosity. Functional groups responsible for low vapor pressure also promote high viscosity. Specifically, carboxylic acid and hydroxyl groups were identified as major contributors to high viscosity. Several studies were carried out to characterize the link between composition and the glass-to-liquid phase transition. Compositions tested include models of organic/inorganic particles and models of complex organic aerosol formed through secondary processes. A simple computational model to predict the amorphous phase diagram was developed and tested. Excellent agreement between model and measurements was obtained for organic/inorganic mixtures. The computational model is simple enough to be included in global model simulations. However, constraints of input parameters such as the Gordon-Taylor constant for binary mixtures for a wide range of complex mixtures have not yet been fully evaluated. Combined, the performed work provides new constraints on the amorphous phase state of organic aerosols.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Aluminum Clad Spent Nuclear Fuel Task 6: Surrogate Sample Preparation and Validation Experiment Test Plan

This document presents the experimental test plan for Task 6: Surrogate Preparation and Validation. Task 6 will produce and validate surrogate oxyhydroxide materials used in other experimental tasks within the larger Aluminum Clad Spent Nuclear Fuel Long Term Dry Storage Project. Task 6 includes both the preparation and characterization of surrogate oxyhydroxide materials as well as the analysis of oxide/oxyhydroxide layers on Savannah River Site Spent Nuclear Fuel Materials. This test plan provides experimental design details and the task’s overall quality assurance approach.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Optimization of Advanced Steels for Cyclic Operation through an Integration of Material Testing, Modeling and Novel Component Test Validation

The efforts in this project were focused in three primary objectives, provided below: • To develop the needed microstructural processing and performance relationships and associated material models for specific constituents in fabricated weldments (such as the parent material, heat affected zone regions and weld metal), • Apply these metallurgical relationships through modeling of a welded pressure bearing power plant component subjected to cyclic operational conditions under both mechanical and thermal loading, and • Validate the model through novel structural feature and component tests. An attempt was made to optimize the heat treatment schedule to reduce or eliminate the presence of boron nitride (BN) in the matrix of the Grade 92 material. BN has been shown to be a primary nucleation source for creep damage. Proper evaluation of material behavior, and as assessed in this research, included the influence of geometric notches (such as those from poor fabrication or design) and metallurgical notches (such as weldments or poorly processed parent material). Better practice methodologies were implemented in the theoretical design of a high-temperature, critical component for cyclic operation. It was demonstrated that vessel testing can be reliably performed and provides a critical link between standard testing, structural assessment and validation. While the goal of an improved Grade 92 steel was not achieved in this project, there is considerable value in applying the documented testing and assessment methodologies to assess material and/or component behavior. This is especially true for materials and/or designs which are expected to be subjected to flexible operating modes. Design of a cycling state of the art thick wall steam header for long term operation with a state of the art ferritic steel was a task in this project. Implementation of that task showed how many factors including plant operating mode, creep strength, creep ductility, fatigue strength, and resistance to crack growth should be considered and evaluated to properly design high temperature components for long term service (200,000 operating hours or more) in a modern Fossil energy power plant. The current ASME non-nuclear boiler design code does not mandate this level of complex analysis nor does it provide all the metallurgical and mechanical properties data needed to perform this kind of design analysis.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2018

Quick Urban and Industrial Complex (QUIC) CBR Plume Modeling System: Validation-Study Document

This document contains information on QUIC validation studies that have been performed to evaluate the wind, pressure, and concentration solutions produced by QUIC. Tests of QUIC's source term models and specialized transport mechanisms (e.g., buoyancy algorithms, particle settling and deposition, liquid pool growth, droplet and pool evaporation) are also provided. A brief description of the experiment, a few example validation results, and references to journal articles, reports, and/or presentations are given. Both LANL and non-LANL sources are provided.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Energy Storage System Safety Documenting and Validating Compliance with Codes and Standards

Energy, environmental, and economic challenges are spurring more widespread consideration and use of energy storage systems (ESSs), which in turn are driving increased development of new ways to store energy electrochemically, mechanically, and thermally. These new methods necessitate an increased focus on ensuring that public health, safety, and welfare are not adversely affected—something that has been addressed for many years through codes, standards, and regulations (CSR5)1. CSRs provide requirements that establish a basis for determining if an ESS is safe, whether electrochemical, mechanical, or thermal and regardless of the range of ESS applications, energy capacities, physical sizes, location, or number installed at any given site. The key to achieving desired safety goals, as memorialized through CSRs, is through documenting and validating compliance with applicable CSRs. The process of documenting and validating compliance, which is a key component to the initial approval as well as continuing acceptance of an ESS installation, is generally called conformity assessment.

25 ENERGY STORAGE↗