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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Use of Percutaneous Aspiration Thrombectomy vs. Anticoagulation Therapy to Treat Acute Iliofemoral Venous Thrombosis: 1-year Follow-up Results of a Randomised, Clinical Trial

PurposeThe purpose of this study was to compare the efficacy of percutaneous aspiration thrombectomy (PAT) followed by standard anticoagulant therapy, with anticoagulation therapy alone, for the treatment of acute proximal lower extremity deep vein thrombosis.MethodsIn this randomised, prospective study, 42 patients with acute proximal iliofemoral deep vein thrombosis documented via Doppler ultrasound examination, were separated into an interventional treatment group (16 males, 5 females, average age 51 years) and a medical treatment group (13 males, 8 females, average age 59 years). In the interventional group, PAT with large-lumen 9-F diameter catheterisation was applied, after initiation of standard anticoagulant therapy. Balloon angioplasty (n 19) and stent implementation (n: 14) were used to treat patients with residual stenosis (>50 %) after PAT. Prophylactic IVC filters were placed in two patients. The thrombus clearance status of the venous system was evaluated by venography. In both the medical and interventional groups, venous patency rates and clinical symptom scores were evaluated at months 1, 3, and 12 after treatment.ResultsDeep venous systems became totally cleared of thrombi in 12 patients treated with PAT. The venous patency rates in month 12 were 57.1 and 4.76 % in the interventional and medical treatment groups, respectively. A statistically significant improvement was observed in clinical symptom scores of the interventional group (PAT) with or without stenting (4.23 ± 0.51 before treatment; 0.81 ± 0.92 at month 12) compared with the medical treatment group (4.00 ± 0.63 before treatment; 2.43 ± 0.67 at month 12). During follow-up, four patients in the medical treatment and one in the interventional group developed pulmonary embolisms.ConclusionsFor treatment of acute deep vein thrombosis, PAT with or without stenting is superior to anticoagulant therapy alone in terms of both ensuring venous patency and improving clinical symptoms. PAT is a safe, inexpensive, and easily performed method of endovascular treatment with a low rate of major complications. Our present findings and literature data suggest that PAT can be used as first-line treatment in proximal deep vein thrombosis patients, especially when thrombolytic treatment is contraindicated.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

A review of MRI evaluation of demyelination in cuprizone murine model

The cuprizone mouse model of non-autoimmune demyelination reproduces some phenomena of multiple sclerosis and is appropriate for validation and specification of a new method of non-invasive diagnostics. In the review new data which are collected using the new MRI method are compared with one or more conventional MRI tools. Also the paper reviewed the validation of MRI approaches using histological or immunohistochemical methods. Luxol fast blue histological staining and myelin basic protein immunostaining is widespread. To improve the accuracy of non-invasive conventional MRI, multimodal scanning could be applied. The new quantitative MRI method of fast mapping of the macromolecular proton fraction is a reliable biomarker of myelin in the brain and can be used for research of demyelination in animals. To date, a validation of MPF method on the CPZ mouse model of demyelination is not performed, although this method is probably the best way to evaluate demyelination using MRI.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Evaluation of Anodized and Electroplated Radioactive Check Sources for Radiological Monitoring Instruments

Radioactive check sources are often used for source checking calibrated instruments to confirm accurate readings are obtained from radiological monitoring instruments. Because of the importance of check sources and their application, PNNL conducted a study to evaluate the effectiveness and accuracy of active sources produced using different construction methods. Eleven, randomly selected check sources of both anodized (five) and electroplated (six) construction were evaluated, along with their calculated decay curves, to determine how well they withstand consistent, multi-year use in the field. Results show that the anodized and electroplated check sources evaluated hold up well enough to continue their use, regardless of wear and tear sustained over years of use. This report provides the source information, empirical data for the 11 anodized and electroplated check sources and their representative decay curves, and it documents the conclusion that anodized and electroplated check sources are reliable for routine use in the field over multiple years.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Gen-0 BWR Modeling Application and Validation (L3 Milestone THM.P18.01)

This milestone report describes the Consortium for Advanced Simulation of Light Water Reactors (CASL) work conducted for completion of the thermal hydraulics Methods (THM) Level 3 milestone L3:THM.P18.01 Gen-0 BWR Modeling Application and Validation. The extension of existing boiling closure designed for Pressurized Water Reactors (PWRs) to the high void fraction condition of Boiling Water Reactors (BWRs) is one of the challenges for Multiphase Computational Fluid Dynamics (M-CFD) applications. In the efforts aimed at developing the advanced boiling closure for BWRs, the baseline closure model, so-called ‘Zero’ closure, has been developed by leveraging the experience gained through the Numerical Nuclear Reactor project. This baseline closure model is physics-based, simplest and robust, but it does not contain any explicit descriptions of the complex high void fraction mechanisms. This is a continuation of the CASL thermal-hydraulic study to develop and assess the CFD-BWR models. In FY-17, the applicability has been evaluated against the international OECD/NRC BFBT benchmark data. In the present work, we assessed the capability of CFD-BWR model for void drift phenomena in the modern BWR fuel designs which make use of both full-length and part-length rods.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2024

Recovery of Neptunium-236g from Photon and Proton-Irradiated Actinide Targets

Neptunium-236g is a rare radionuclide used as a tracer for neptunium-237 analyses. The availability of 236gNp is limited and the viable production routes are costly, time consuming, and only produce trace quantities of the desired product. For this work, two known production methods were tested to determine product recovery, purity, and viability for use as a tracer. The first method utilizes a photon-irradiated 237Np target to produce 236gNp by the 237Np(?,n)?236Np reaction. The second method utilizes the 238U(d,4n) ?236Np reaction. These production routes were evaluated previously, and the former was considered ineffective without isotope separation and the latter was not well-characterized for the 236mNp/236gNp production ratio. Recent resurgence of electromagnetic isotope separation technology has enabled at least partial recovery of 236gNp from part-per-million abundance feeds produced by the photonuclear reaction. To address the lack of production data for the second method, a deuteron-irradiated depleted uranium target was chemically processed to recover and purify the Np for abundance and ratio analyses. The status and current analytical results for each production method are presented.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2026

Dual particle imaging using time-of-flight neutron classification

Fast-neutron imaging technology is well-suited for passive nuclear material monitoring, secondary inspection of flagged cargo, and wide-area search for lost neutron sources. However, imaging systems that use pulse shape discrimination for event classification require complex pulse waveform analysis. In this work, we evaluate time-of-flight (TOF) based particle classification as an alternative solution for fast-neutron imaging by classifying all events with a TOF above a maximum threshold as neutrons. We measured a Cf-252 source next to Cs-137 using a 12-bar organic-glass scintillator array. By varying the TOF thresholds for neutron identification, we demonstrate a clear trade-off between event yield and backprojection image fidelity, with stricter thresholds improving precision at the cost of statistics, TOF thresholded data generated an image that predicted the neutron source direction with 20% reduced mean central angle prediction error compared to a traditional pulse shape discrimination (PSD) method with comparable event count. Time-of-flight particle classification shows promise as an alternative to pulse shape discrimination systems for fast neutron imaging systems looking to minimize costs and size of electronics with comparable imaging quality. The sources used demonstrate that the method is effective in classifying measured neutrons in a measurement environment with 150 μCi Cs-137 and 1.6 × 10 6 n/s Cf-252 sources positioned at distances of 66 cm and 81 cm from the detector. Additionally, the method classifies low-energy neutron events that pulse shape discrimination removes, so a combination of both methods would result in a higher overall neutron event efficiency.

Heriot, William [Univ. of Michigan, Ann Arbor, MI ↗
DOE OSTI2015

Order dependence of the profile of the intensities of multiple-quantum coherences

A modification of the widespread phenomenological model theory of multiple-quantum (MQ) nuclear magnetic resonance spectra of a single cluster of correlated spins has been developed. In contrast to the mentioned theory, the size distribution of such clusters has been consistently taken into account. To obtain the distribution, solutions for the amplitudes of the expansion in the complete set of orthogonal operators are used. Expressions specifying the dependence of the profile of the intensities of MQ coherences on their number n (order) have been obtained. The total form of the dependence has been evaluated by means of the numerical implementation of the resulting expressions. The asymptotic expressions for large n values (wings of the spectrum) have been obtained analytically by the saddle-point method. It has been shown that the dependence under study has a Gaussian central part and exponential wings. The results obtained are in agreement with the previous calculations for some model systems and existing experimental data.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Analysis of Data Fusion Between Waveform Events and Radionuclide Detections Reported in 2021 by the International Data Centre

During this project, we assessed the percentage of events reported by the International Data Centre (IDC) that are candidates for evaluation using data fusion methods. We calculated the percentage of waveform (seismic, hydroacoustic, infrasound, SHI) events that may be associated with radionuclide (RN) detections and vice versa. For this task, data fusion means identifying RN detections that may be associated with SHI events. The task of producing a fused SHI and RN bulletin is included in the IDC operational manual. As of 2022, the production of a fused event bulletin remains incomplete, largely because methods for producing the bulletin are under development. Nonetheless, simple methods for data fusion have been developed and preliminary software tools are available at the IDC to associate SHI events and RN detections. This report is a first look at the percentage of SHI events that may be candidates for fusion with RN detections or bulletins. One year of IDC bulletin data (2021) is considered in this report. It is important to note that there were no known nuclear explosions during this time period. Hence, we expect that events during this time period would generate SHI and RN signals. If many SHI events are candidates for fusion with RN data, greater priority should be placed on establishing screening procedures before and/or during the fusion process. By contrast, if the number of candidate events is diminishingly small, then data fusion is not a driver for further development of event or detection screening at the IDC. LLNL reviewed the events reported in the Standard Event Bulletin (SEB) and determined which events are candidates for fusion with the Reviewed Radionuclide Reports (RRR). Much of the work involves establishing a metric or metrics for determining whether a Reviewed Event Bulletin (REB) event is a candidate for data fusion.

58 GEOSCIENCES↗
DOE OSTI2023

Complete Performance Comparison Between the Optimized Image Construction Algorithm (U-MBIR) and the Existing Reconstruction Algorithm for Detecting Defects and Damage in Concrete

Reinforced concrete (RC) is a composite material subjected to mechanical, thermal, and chemical loads throughout its service life. Because of these external stressors and the susceptibility of RC structural members to shrinkage and microcracking, the material degrades throughout its life cycle. This deterioration can lead to a decrease in member capacity and, ultimately, poses a threat to the structural integrity. Thus, it is crucial that the damage caused by aging and degradation be monitored and assessed at regular intervals throughout the material’s service life. Since coring of the material is typically not feasible for in-service structural systems, non-destructive evaluation (NDE) methodologies are used to assess remaining structural capacity. NDE methods enable surface and subsurface examination without damaging or degrading the medium. Moreover, RC is a critical component of nuclear power plants; thus, its safety and reliability must be thoroughly examined throughout the life cycle of the structural system. Ultrasonic measurements have been an industry standard for both surface and subsurface inspections. To this end, Oak Ridge National Laboratory (ORNL) has researched and developed advanced image reconstruction algorithms to capture internal damage. The results and discussion presented herein summarize the current state of the ultrasonic model–based iterative reconstruction (U-MBIR) algorithm developed at ORNL. More specifically, this report presents a comparison between reconstruction images produced via a widely employed ultrasonic NDE technique—the synthetic aperture focusing technique (SAFT)—and the ORNL-developed U-MBIR algorithm. These NDE methodologies are demonstrated using ultrasonic data collected from four concrete specimens. Overall, the U-MBIR algorithm eliminates artifacts and noise that are typically present within the SAFT reconstructions, and it shows defects and anomalies more clearly than the SAFT images. In conclusion, this algorithm is suitable for identifying concrete defects, although more improvements and optimization could be done to better define internal defects.

36 MATERIALS SCIENCE↗
DOE OSTI2015

SU-E-T-678: Response Calibration Using Electron Depth-Dose Data for MRI-Based 3D Polymer Gel Dosimetry

Purpose: To evaluate a calibration method using the depth-dose data of an electron beam for MRI-based polymer gel dosimetry. Methods: MAGAT was manufactured in-house to fill two 400mL-cylindrical phantoms and nine 22mL-glass vials. Phantom-A was irradiated along the cylinder axis with a 9MeV electron beam of 6 cm x 6 cm field size (FS). Phantom-B was irradiated with a 6MV photon beam of 3 cm x 3 cm FS by a 360-degree arc technique. Eight vials were irradiated in a water-bath to various doses with a 20 cm x 20 cm FS 6MV photon beam. All irradiated phantoms and one un-irradiated vial were scanned with a 3T MRI scanner to obtain the spin-spin relaxation rate (R2) distributions. By comparing the measured R2-to-depth data with the known depth-dose data for Phantom-A, R2-to-dose calibration data were obtained (e-beam method). Another calibration data were obtained from the 9 vials data (9-vial method). We tested two regression equations, i.e., third-order polynomial and tangent functions, and two dose normalization methods, i.e., one-point and two-point methods. Then, these two calibration methods were used to obtain the 3D dose distribution of Phantom-B and evaluated by comparing the measured data with the dose distribution from a treatment planning system. The comparison was made with gamma passing rate (2%/2mm criteria). Results: We did not observe a clear advantage of the e-beam method over the 9-vial method for the 3D dose comparison with the test case. Nevertheless, we found that the e-beam method required a smaller dose scaling for the dose comparison. Furthermore, the tangent function showed better data fitting than the polynomial function with smaller uncertainty of the estimated coefficients. Conclusions: Considering the overall superior performance, we recommend the e-beam method with the tangent function as the regression equation and one-point dose normalization for the MRI-based polymer gel dosimetry.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Instrumental resolution as a function of scattering angle and wavelength as exemplified for the POWGEN instrument

The method of angular- and wavelength-dispersive (e.g. two-dimensional) Rietveld refinement is a new and emerging tool for the analysis of neutron diffraction data measured at time-of-flight instruments with large area detectors. Following the approach for one-dimensional refinements (using either scattering angle or time of flight), the first step at each beam time cycle is the calibration of the instrument including the determination of instrumental contributions to the peak shape variation to be expected for diffraction patterns measured by the users. The aim of this work is to provide the users with calibration files and – for the later Rietveld refinement of the measured data – with an instrumental resolution file (IRF). This article will elaborate on the necessary steps to generate such an IRF for the angular- and wavelength-dispersive case, exemplified for the POWGEN instrument. A dataset measured on a standard diamond sample is used to extract the profile function in the two-dimensional case. It is found that the variation of reflection width with 2θ and λ can be expressed by the standard equation used for evaluating the instrumental resolution, which yields a substantially more fundamental approach to the parameterization of the instrumental contribution to the peak shape. Geometrical considerations of the POWGEN instrument and sample effects lead to values for Δθ, Δt and ΔL that yield a very good match to the extracted FWHM values. In a final step the refinement results are compared with the one-dimensional, i.e. diffraction-focused, case.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

A genetic meta-algorithm-assisted inversion approach: hydrogeological study for the determination of volumetric rock properties and matrix and fluid parameters in unsaturated formations

An evolutionary inversion approach is suggested for the interpretation of nuclear and resistivity logs measured by direct-push tools in shallow unsaturated sediments. The efficiency of formation evaluation is improved by estimating simultaneously (1) the petrophysical properties that vary rapidly along a drill hole with depth and (2) the zone parameters that can be treated as constant, in one inversion procedure. In the workflow, the fractional volumes of water, air, matrix and clay are estimated in adjacent depths by linearized inversion, whereas the clay and matrix properties are updated using a float-encoded genetic meta-algorithm. The proposed inversion method provides an objective estimate of the zone parameters that appear in the tool response equations applied to solve the forward problem, which can significantly increase the reliability of the petrophysical model as opposed to setting these parameters arbitrarily. The global optimization meta-algorithm not only assures the best fit between the measured and calculated data but also gives a reliable solution, practically independent of the initial model, as laboratory data are unnecessary in the inversion procedure. The feasibility test uses engineering geophysical sounding logs observed in an unsaturated loessy-sandy formation in Hungary. The multi-borehole extension of the inversion technique is developed to determine the petrophysical properties and their estimation errors along a profile of drill holes. The genetic meta-algorithmic inversion method is recommended for hydrogeophysical logging applications of various kinds to automatically extract the volumetric ratios of rock and fluid constituents as well as the most important zone parameters in a reliable inversion procedure.

58 GEOSCIENCES↗
DOE OSTI2014

Inspection design using 2D phased array, TFM and cueMAP software

A simulation suite, cueMAP, has been developed to facilitate the design of inspection processes and sparse 2D array configurations. At the core of cueMAP is a Total Focusing Method (TFM) imaging algorithm that enables computer assisted design of ultrasonic inspection scenarios, including the design of bespoke array configurations to match the inspection criteria. This in-house developed TFM code allows for interactive evaluation of image quality indicators of ultrasonic imaging performance when utilizing a 2D phased array working in FMC/TFM mode. The cueMAP software uses a series of TFM images to build a map of resolution, contrast and sensitivity of imaging performance of a simulated reflector, swept across the inspection volume. The software takes into account probe properties, wedge or water standoff, and effects of specimen curvature. In the validation process of this new software package, two 2D arrays have been evaluated on 304n stainless steel samples, typical of the primary circuit in nuclear plants. Thick section samples have been inspected using a 1MHz 2D matrix array. Due to the processing efficiency of the software, the data collected from these array configurations has been used to investigate the influence sub-aperture operation on inspection performance.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Discriminative versus generative approaches to simulation-based inference

Most of the fundamental, emergent, and phenomenological parameters of particle and nuclear physics are determined through parametric template fits. Simulations are used to populate histograms which are then matched to data. This approach is inherently lossy, since histograms are binned and low-dimensional. Deep learning has enabled unbinned and high-dimensional parameter estimation through neural likelihood(-ratio) estimation. We compare two approaches for neural simulation-based inference (NSBI): one based on discriminative learning (classification) and one based on generative modeling. These two approaches are directly evaluated on the same datasets, with a similar level of hyperparameter optimization in both cases. In addition to a Gaussian dataset, we study NSBI using a Higgs boson dataset from the FAIR Universe Challenge. We find that both the direct likelihood and likelihood ratio estimation are able to effectively extract parameters with reasonable uncertainties. For the numerical examples and within the set of hyperparameters studied, we found that the likelihood ratio method is more accurate and/or precise. Both methods have a significant spread from the network training and would require ensembling or other mitigation strategies in practice.

high energy physics↗
DOE OSTI2013

Comparing modern measurements of the {sup 11}B(d,n{gamma}{sub 15.1}){sup 12}C excitation function with previous values

A possible means of active interrogation of special nuclear materials is detection of signature emissions following induced photofission. This method requires a probe gamma-ray beam to induce the photofission. The {sup 11}B(d,n{gamma}{sub 15.1}){sup 12}C reaction is a candidate for the source of this probe beam. The reaction is prolific and the produced 15.1 MeV gamma-ray is close to a photofission cross-section peak for {sup 235,238}U and {sup 238,239}Pu. In order to model an active interrogation system using the {sup 11}B(d,n{gamma}{sub 15.1}){sup 12}C reaction as a source probe an accurate value for its differential crosssection must be included in data libraries. Measurements of the differential cross-section for the {sup 11}B(d,n{gamma}{sub 15.1}){sup 12}C reaction have been carried out with a BGO detector and found to differ from previous measurements reported by Kavanagh (1958) and Kuan (1964). The discrepancy in the measurements may be explained by examining the detector response function used by Kavanagh and presumably Kuan to that modeled with MCNP5. A comparison of the MCNP5 and Kavanagh detector response functions normalized to the 15.1 MeV gamma-ray peak pulse height shows a factor of approximately 1.7 difference in integrated counts. Applying this correction to the differential cross-section previously reported by Kuan brings the values into agreement, within uncertainties, to the more recent measurements. The evaluation of the detector response function for the 15.1 MeV gamma-ray signal in the NaI detector reported by Kavanagh to that modeled by MCNP5 is shown. This result is applied to the comparison of recent measurements on the {sup 11}B(d,n{gamma}{sub 15.1}){sup 12}C reaction differential cross-section to those previously reported.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

Benchmark Evaluation of the Medium-Power Reactor Experiment Program Critical Configurations

A series of small, compact critical assembly (SCCA) experiments were performed in 1962-1965 at the Oak Ridge National Laboratory Critical Experiments Facility (ORCEF) for the Medium-Power Reactor Experiment (MPRE) program. The MPRE was a stainless-steel clad, highly enriched uranium (HEU)-O 2 fueled, BeO reflected reactor design to provide electrical power to space vehicles. Cooling and heat transfer were to be achieved by boiling potassium in the reactor core and passing vapor directly through a turbine. Graphite- and beryllium-reflected assemblies were constructed at ORCEF to verify the critical mass, power distribution, and other reactor physics measurements needed to validate reactor calculations and reactor physics methods. The experimental series was broken into three parts, with the third portion of the experiments representing the beryllium-reflected measurements. The latter experiments are of interest for validating current reactor design efforts for a fission surface power reactor. The entire series has been evaluated as acceptable benchmark experiments and submitted for publication in the International Handbook of Evaluated Criticality Safety Benchmark Experiments and in the International Handbook of Evaluated Reactor Physics Benchmark Experiments .

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2014

WE-G-18A-04: 3D Dictionary Learning Based Statistical Iterative Reconstruction for Low-Dose Cone Beam CT Imaging

Purpose: To develop a 3D dictionary learning based statistical reconstruction algorithm on graphic processing units (GPU), to improve the quality of low-dose cone beam CT (CBCT) imaging with high efficiency. Methods: A 3D dictionary containing 256 small volumes (atoms) of 3x3x3 voxels was trained from a high quality volume image. During reconstruction, we utilized a Cholesky decomposition based orthogonal matching pursuit algorithm to find a sparse representation on this dictionary basis of each patch in the reconstructed image, in order to regularize the image quality. To accelerate the time-consuming sparse coding in the 3D case, we implemented our algorithm in a parallel fashion by taking advantage of the tremendous computational power of GPU. Evaluations are performed based on a head-neck patient case. FDK reconstruction with full dataset of 364 projections is used as the reference. We compared the proposed 3D dictionary learning based method with a tight frame (TF) based one using a subset data of 121 projections. The image qualities under different resolutions in z-direction, with or without statistical weighting are also studied. Results: Compared to the TF-based CBCT reconstruction, our experiments indicated that 3D dictionary learning based CBCT reconstruction is able to recover finer structures, to remove more streaking artifacts, and is less susceptible to blocky artifacts. It is also observed that statistical reconstruction approach is sensitive to inconsistency between the forward and backward projection operations in parallel computing. Using high a spatial resolution along z direction helps improving the algorithm robustness. Conclusion: 3D dictionary learning based CBCT reconstruction algorithm is able to sense the structural information while suppressing noise, and hence to achieve high quality reconstruction. The GPU realization of the whole algorithm offers a significant efficiency enhancement, making this algorithm more feasible for potential clinical application. A high zresolution is preferred to stabilize statistical iterative reconstruction. This work was supported in part by NIH(1R01CA154747-01), NSFC((No. 61172163), Research Fund for the Doctoral Program of Higher Education of China (No. 20110201110011), China Scholarship Council.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

AN ESTIMATE OF SPENT NUCLEAR FUEL MECHANICAL LOADS IN THE GENERAL 30 CM PACKAGE DROP SCENARIO

The US Department of Energy Spent Fuel and Waste Science and Technology (SFWST) program is performing research to determine the mechanical loading conditions applied to spent nuclear fuel (SNF) during normal conditions of transport to inform mechanical tests of SNF and close an important knowledge gap related to the practical disposition of SNF in the US. Researchers at Pacific Northwest National Laboratory (PNNL) have completed an extensive finite element study to characterize and estimate the potential mechanical loads on SNF during a hypothetical 30 cm drop of an SNF transportation package. This modeling study is validated with test data collected by the SFWST program during a physical test campaign that included one-third scale package drop tests and full-scale single fuel assembly drop tests. The test campaign was led by Sandia National Laboratories (SNL) and included international collaboration with Equipos Nucleares S.A, S.M.E (ENSA) and Bundesanstalt für Materialforschung und -prüfung (BAM). The key contribution of the modeling study is to go beyond the limitations of the limited number of physical tests to estimate the impact response to variations in impact angle, initial gap conditions, fuel assembly design, burnup and other parameters that affect the mechanical loads. The methodology of this study included a classic parametric study to calculate the impact response of highly detailed fuel assemblies over many combinations of parameters. Models of a 17x17 pressurized water reactor fuel assembly and a generic 10x10 boiling water reactor fuel assembly were both used in this study to cover the major fuel assembly types in the US inventory. Over 2,000 impact responses were calculated. The results of the parametric study were evaluated using traditional methods and basic statistics. The results were also used to construct a damage model using multiple nonlinear regression techniques to predict the mechanical loads over the full range of all input parameters. The damage model was found to work very well for all impact angle cases where the cask came to rest on its side. It was concluded that end drop cases where the cask remained vertical (instead of tipping over onto its side) were not sufficiently characterized by the current set of parametric study cases to include in the damage model, but it was not a priority to fully investigate that range because the highest mechanical loads were observed in the broader range of side impact cases. This modeling work provides sufficient insight into the mechanical loads on SNF during a hypothetical 30 cm package drop that, when considered along with the physical test data collected by the SNL-led team, the SFSWT program can consider the knowledge gap closed.

Klymyshyn, Nicholas A.↗