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This note provides a summary of what isotopes and nuclear reaction chains would be of interest to astrophysicists using FLAG. It is meant to suggest nuclear data and nuclear burning networks that could be added to FLAG's default libraries to make it a more attractive code option for astronomers.
The work presented in this report applies the MELCOR code to evaluate potential accidents in non-reactor nuclear facilities, focusing on Design Basis Accidents. Ten accident scenarios were modeled using NRC's best-estimate severe accident analysis code, MELCOR 2.2. The accident scenarios simulated a range of explosions and/or fires related to a nuclear fuel reprocessing facility. The objective was to evaluate the radionuclide source term to the environment following initiating explosion and/or fire events. The simulations were performed using a MELCOR model of the Barnwell Nuclear Fuel Plant, which was decommissioned before beginning reprocessing operations. Five of the accident scenarios were based on the Class 5 Design Basis Accidents from the Final Safety Analysis Report. Three of the remaining accident scenarios include sensitivity studies on smaller solvent fires. The final two accidents included an induced fire from an initial explosion. The radionuclide inventory was developed from ORIGEN calculations of spent PWR fuel with an initial enrichment of 4.5% U-235 by weight. The fuel aged for five years after a final 500-day irradiation cycle. The burn-up was conservatively increased to 60 GWd/MTU to bound current US operations. The results are characterized in terms of activity release to the environment and the building decontamination factor, which is related the leak path factor used in Department of Energy safety analyses. The MELCOR 2.2 results consider adverse consequences to the filters, ventilation system, and structures as a result of the explosions and fires. The calculations also include best-estimate models for aerosol transport, agglomeration, and deposition. The new calculations illustrate best-estimate approaches for predicting the source term from a reprocessing facility accident.
Computational analysis of the depletion of nuclear fuel is crucial to the accurate modeling of the time-dependent behavior of nuclear reactors. The reactor physics application MAMMOTH is modified to compute radioactive decay and neutron transmutation in order to model physical processes which occur within nuclear reactors as reactor fuel is burned. The ability to read decay and cross-section data files of other codes are also added and the addition of a standardized decay and transmutation XML file format for MAMMOTH, known as ISOXML. Comparisons between MAMMOTH and the Oak Ridge Isotope Generation (ORIGEN) code are performed to demonstrate the improved precision possible with MAMMOTH. In addition, several tests are run to demonstrate the ability of MAMMOTH to model decay and transmutation processes involving hundreds of isotopes. Future work will focus on solving depletion problems with multiple neutron energy groups and the implementation of predictor-corrector methods, several of which are described in this work.
Mixing of cold, higher-Z elements into the fuel region of an inertial confinement fusion target spoils the fusion burn efficiency. This mixing process is driven by both "turbulent" and "atomic" mixing processes, the latter being modeled through transport corrections to the basic hydrodynamic models. Recently, there has been a surge in the development of dense plasma transport modeling and the associated transport coefficients; however, experimental validation remains in its infancy.
This study evaluates a target station at the Los Alamos Neutron Science Center dedicated to the mission of irradiating structural materials in an environment that is nearly prototypic of the radiation environment experienced by the first wall of a magnetically-confined fusion reactor burning D-T fuel. Such a station could be located in the existing Area A experimental hall and be driven by an 800-MeV, 1-MW proton beam delivered by the LANSCE accelerator. A neutronics assessment of a target concept shows it satisfies all of the key parameter guidelines stated in the Summary Report on the Fusion Prototypic Neutron Source Workshop.
In this project, we have further developed the state-of-the-art fusion simulation code, gyrokinetic toroidal code (GTC), for studying the energetic particle (EP) transport in the 3D equilibrium. We have applied the new capabilities to simulate the EP transport by the Alfven eigenmodes in stellarators and by 3D magnetic islands in tokamaks. As part of V&V efforts for 3D capability, the 3D capabilities of GTC have been applied to study thermal transport in stellarators and tokamak with 3D magnetic fields by microturbulence, which could cause additional EP loss. Effects magnetic islands on neoclassical bootstrap current have also been studied. The computational capability developed and physics learned in this project are in support of fusion SciDAC Center for Integrated Simulation of Energetic Particles in Burning Plasmas (ISEP). During this project, the PI has supervised 6 postdoctoral researchers and 4 PhD students at the University of California, Irvine. A complete list of 49 publications and 23 invited talks partially supported by this grant since 7/2015 appears at the end of this report. Five key publications closely related to this project are highlighted in this report.
The LANL Weapons Response Group is charged with making determinations for a wide range of scenarios regarding the probability that inadvertent ignition of the high explosive (HE) components might cause nuclear yield, or dispersal of special nuclear material, during assembly/disassembly operations at the Pantex Plant. These scenarios are categorized based on the nature of the ignition causing stimulus, i.e. impact, electrostatic discharge, pressure-shear, etc. However, for all of these scenarios, regardless of how ignition is achieved, there must also be a credible path for the burning HE to transition to detonation for yield or dispersal to occur. If it can be determined that there is no feasible path for deflagration-to-detonation transition (DDT), the scenario space that requires mitigative action is greatly reduced. The strategy to support Weapons Response determinations is to use experimentation and observation to evaluate HE response in severe “overtest” configurations. To increase with confidence in the margins of HE response, these overtests are designed, by controlling parameters known to enhance HE response violence, to be more severe than what is ever encountered in the actual operations environment at the Plant. This study is focused on DDT in pentaerythritol tetranitrate (PETN), a high explosive that is used in LANL’s detonators. PETN is known to be able to DDT at certain densities, and this represents a safety concern. The PETN in LANL’s detonators is commonly a density of 1.65 g cm -3 . However, DDT has never been observed at this density in PETN. In this work, we studied the DDT reaction in 1.65 g cm -3 PETN to determine whether DDT is possible at this density, and if so, what length of PETN is required for the transition to occur. In any of the tests conducted, we did not observe DDT in 1.65 g cm -3 PETN. It is possible that the DDT length for 1.65 g cm -3 PETN is greater than 6” (the available run length in the experiments), but this length is simply not available in a detonator, and is therefore not a concern.
This Environmental Restoration Operations (ER) Consolidated Quarterly Report (ER Quarterly Report) provides the status of ongoing corrective action activities being implemented at Sandia National Laboratories, New Mexico (SNL/NM) during the July - September 2019 reporting period. Table I-1 lists the Solid Waste Management Units (SWMUs) and Areas of Concern (A0Cs) currently identified for corrective action at SNL/NM. This section of the ER Quarterly Report summarizes the work completed during this quarterly reporting period at sites undergoing corrective action. Corrective action activities were conducted during this reporting period at the three groundwater AOCs (Burn Site Groundwater [BSG] AOC, Technical Area-V [TA-V] Groundwater [TAVG] AOC, and Tijeras Arroyo Groundwater [TAG] AOC). Corrective action activities are deferred at the Long Sled Track (SWMU 83), the Gun Facilities (SWMU 84), and the Short Sled Track (SWMU 240) because these three sites are active mission facilities. These three active mission sites are located in Technical Area-III. There were no SWMUs or AOCs in the corrective action complete regulatory process during this quarterly reporting period.
This report will describe the one test conducted during phase III of the Pipe Overpack Container (POC) test campaign, present preliminary results from these tests, and discuss implications for the Criticality Control Overpack (CCO). The goal of this test was to see if aerosol surrogate material inside the Criticality Control Container (CCC) gets released when the drum lid of the CCO comes off during a thirty-minute long, fully-engulfing, fire test. As expected from POC tests conducted in Phase I and II of this test campaign, the CCO drum lid is ejected about one minute after the drum is exposed to fully-engulfing flames. The remaining pressure inside the drum is high enough to eject the top plywood dunnage a considerable distance from the drum. Subsequently, most of the bottom plywood dunnage supporting the CCC burns off during and after the fire. High pressure buildup inside the CCC and inside two primary containers holding the surrogate powder also results in damage to the filter media of the CCC and the filter-house, thread attachment of the primary canisters. No discernable release of surrogate powder material was detected from the two primary containers when pre- and post-test average mass were compared. However, when the average masses are corrected to account for possible uncertainties in mass measurements, error overlap does not preclude the possibility that some surrogate powder mass may have been lost from these primary canisters. Still, post-test conditions of the secondary canisters enclosing these two primary canisters suggest it is very unlikely this mass loss would have escaped into the CCC.
The goal of this project was to develop an electrochemical process for depolymerization of biorefinery lignin to industrial chemicals, most notably as replacements in resins. The project team consisted of Ohio University (lead organization), Hexion, Inc. and Lakehead University. There were six distinct project tasks, consisting of Initial Validation, Development of TiO 2 Nanowire-supported Ni-Co Electrocatalysts, Electrochemical Characterization of TiO 2 Nanowire-supported Ni-Co Electrocatalysts, Development of Electrochemical Flow Reactor for Production of Industrial Chemicals and Hydrogen, Product Formulations and Integrated Biorefinery Analysis. The project was divided into two budget periods. After intermediate validation near the end of Budget Period 1, the project was discontinued. This final report is intended to highlight major project objectives and results. Technical metrics were developed between the project team and the DOE validation team during the initial validation period. Critical technical metrics included conversion of lignin to products and product selectivity. Desired products were low molecular weight aromatic compounds in the 150-300 MW range. We targeted this class of compounds because of their potential to replace petroleum derivatives in resin formulations. Electrochemical oxidation of biorefinery lignin can lead to significant lignin depolymerization and conversion, with >40% of the lignin reacted. However, product stream analysis is extremely difficult. We were not able to adequately quantify the concentration of the primary oxidation products, or to determine with any degree of certainty what the product selectivity was. The project team initially proposed analytical techniques such as GC-MS to identify product distributions. However, due to 1) difficulty in extracting products into an organic phase suitable for GC analysis and 2) the wide range of product compounds with similar structures, GC-MS analysis was difficult to perform. The project team did have some success with NMR spectroscopic analysis, but not enough so to adequately identify product selectivity. By UV-vis spectroscopy and statistical analysis, we were able to confirm achieving the technical milestone for lignin conversion, and achieved at least 40% conversion by the electrochemical oxidation technique. However, we were not able to confirm product selectivity using GC-MS analysis, as originally postulated. Despite these difficulties, we were able to incorporate the product stream into a resin, and observed better resin synthesis behavior using the oxidized lignin versus the unoxidized lignin. However, no resin synthesized with oxidized biorefinery lignin met the commercial standards for resin quality. One potential problem with electrochemical oxidation of biomass is the competing oxygen evolution reaction (OER) at the reactor anode. We observed that, especially at higher anode potentials, the OER can consume up to 50% of the energy input to the system, meaning that much of the energy goes toward generation of an essentially worthless product (O 2 ). However, we also observed that the OER can be avoided almost entirely at lower potentials. These uncertainties made assigning a value to the electrochemical reactor product stream difficult. Any product generated electrochemically would have to be valuable enough to offset the additional cost of electricity incurred, including electricity to run the electrochemical reactor and the additional electricity that must be purchased because some of the lignin (which is currently burned in biorefineries to recover energy) is diverted to the electrochemical reactor. It is not clear at this time whether the product stream has sufficient economic value to offset these additional electricity costs. The two most promising areas for this project in terms of demonstrating economic feasibility are product stream analysis and resin synthesis. In particular, product stream analysis has proven to be difficult. With additional time, we would refine analytical techniques to better understand key product stream characteristics, such as aromatic compound content. Evaluating the product streams in resin synthesis would likely provide more information on the economic value of the product stream. If we could determine that value, then we would be able to better evaluate whether the electrochemical conversion approach is feasible. The details of this work are presented in the following final report. The report is organized into individual tasks for clarity, although all tasks were integrated and many occurred simultaneously.
Understanding the relevant turbulent transport mechanisms at the edge of a high-performance tokamak is essential for predicting and optimizing the H-mode pedestal structure in future burning plasma devices. Global electromagnetic gyrokinetic simulations will be performed based on representative experimental pedestal scenarios in order to clarify which instabilities are most important for each of the particle and heat transport channels. Edge transport modeling will be performed in order to estimate and bound the particle and heat sources—e.g., the ionization density source and the atomic energy loss channels due to ionization, charge exchange, and radiation. Comparisons will be made with data from the DIII-D, JET, C-Mod and NSTX or MAST experiments.
The edge pedestal is a vital component in achieving overall high confinement in a magnetic fusion device. Therefore, obtaining a physics understanding and predictive capability for the pedestal height and structure is a major goal of domestic and international fusion research. Great progress has been made in understanding the pressure limits imposed by MHD stability on pedestals in tokamaks. It is now clear, though, that the goal of predictive capability for the pedestal structure requires advances in the physics understanding of the separate structure of density and temperature profiles in the pedestal region. A key challenge is to understand the importance of particle sources in determining the density pedestal and project to burning plasma scenarios. Experiments on DIIID and archived data from C-Mod, DIII-D, and NSTX will be used to test how fueling, reduced recycling, and transport affect the density pedestal structure. The role of divertor geometry strongly affects ionization properties and thus its effect upon the pedestal structure will be investigated. US researchers involved in collaborative activities on international experiments and at university facilities may gather, analyze and contribute data to this research effort.
The interaction of the boundary plasma with the material surfaces in magnetically confined plasmas is among the most critical problems in fusion energy science. In FY2018, perform high performance computing simulations with coupled boundary plasma physics and materials surface models to predict the fuel recycling and tritium retention of the ITER divertor for D-T burning plasma conditions, accounting for erosion, re-deposition and impurity transport in the plasma boundary, and an initial evaluation of the influence of material deposition on the recycling and retention.
One of the principal issues preventing the widescale deployment of Concentrating Solar Power (CSP) technologies for power and process heat generation is the high cost per unit energy produced. While the operating expenses of a solar plant are often far less than those of a comparable natural gas plant due to zero fuel costs, the increased capital costs of the system, and the collector field in particular, are a significant barrier to project feasibility. Hyperlight Energy has been funded under the DOE COLLECTS program to further develop its novel Linear Fresnel Reflector (LFR) design to meet the DOE’s programmatic goal of creating a solar collector that has an installed cost of less than $\$$99/m2 with a pathway towards a future price of $\$$50/m2. Hyperlight Energy has a unique, inexpensive design featuring four-inch-wide mirror slats mounted on 48 ft long extruded plastic D-profile tubes. By removing the steel and concrete of a traditional collectors Hyperlight is able to drastically decrease the materials and fabrication costs of the primary reflectors. The goal of this project was to prove the manufacturability of these reflectors, install a half-acre system of the collector, and test the performance of the field to determine the actual cost of the energy produced by the solar field. During the course of the project the half-acre system was successfully manufactured and deployed at the company’s demonstration site in Brawley, CA. The total collector cost came in under the desired $\$$99/m2 goal and proved the feasibility of this new type of solar field. With further planned cost reductions the DOE’s ultimate goal of $\$$50/m2 appears to be achievable. The data generated from this project has already been sufficient to secure Hyperlight Energy’s first commercial project, and continued operations will help to validate the product’s lifespan and performance over time. This will provide invaluable support for future installations. Hyperlight Energy has won a contract for a three-acre commercial project, but the company plans to aggressively pursue multiple similar and larger-scale projects in the near future. At present, these projects will serve to replace natural gas fired boilers in industrial processes, reducing the emissions of the associated plants. In the future, potential project sites will expand to include enhanced oil recovery (EOR) and other uses in the transportation fuel pathway, leading to fuels with a lower carbon intensity (CI). This path will allow renewable energy to begin to make an impact on the industrial process heat sector, which is one the primary consumers of natural gas and other fossil fuels in the country, and which is beyond the scope of other existing renewable technologies that exclusively generate electricity. Only by replacing the fossil fuels burned in industrial processes will the DOE’s emissions goals be achieved.
This thesis defense covers Background/Motivation, High-Temperature SDT Measurements of PBX 9502, Neutron Scattering Measurements of PBX 9502, Reactive Burn Modeling of PBX 9502 Using SURF, Conclusion, and Future Work.
The following modeling assumptions and source term that is provided in the attachments to this document are meant to serve as a guide to the presentation delivered on April 23rd, 2020, to the San Joaquin Air District Permit Services slides. This analysis is in response to the District’s “Project Incompleteness Letter” (Facility Number: N-472 and Project Number: N-1173492) regarding the potential for depleted uranium (DU) to be resuspended from areas of contaminated soil at Site 300 as a result of high explosive (HE) experiments increased to a requested permitted maximum of 1,000 pound detonations with an annual HE throughput not to exceed 7,500 pounds per year. LLNL has taken every step in the radiological health risk concerns in the modeling assumptions and final source term to be at a level of maximum conservativeness. As an example, forty soil samples were taken in the B-851 area (LLNL-AR-738708 – 2018) and assayed for uranium-234, uranium-235, and uranium-238 concentrations. The maximum uranium soil concentrations were used in the assumptions (potential for resuspended dust occurring from detonation experiments) and not the use of median uranium soil concentrations – a more realistic outcome. Additionally, these uranium soil concentrations were considered to be at 100% uptake in the vegetation for prescribed burns; vegetation uptake factors were not used as that would lower the final source term. This level of conservativeness was maintained throughout the modeling assumptions.
Accurate predictive modeling of high explosives in abnormal conditions, such as a fire, is critical to personnel safety. Modeling depends heavily on precise physical characterization of the high explosive in question. The aim of this thesis was to characterize the detonation response to shock and the microstructure at high-temperature (250°C) of PBX 9502 and use these data to attempt to model these results using a new reactive burn model called SURF (Scaled Uniform Reactive Front). In order to characterize the shock response of PBX 9502 at high-temperature a 1D gas gun experiment was designed and executed that provided shock to detonation transition data. These data were then used to do a preliminary calibration of SURF for PBX 9502 at 250°C. Small-angle neutron scattering (SANS) was employed to characterize the void morphology of PBX 9502 as a function of temperature. This was done in order to feed a modified version of SURF called physically informed - SURF (π-SURF) which uses the void size and quantity distribution data as measured by SANS along with the deflagration and detonation characteristics of a high explosive to inform the SURF model. The π-SURF model was then used to model both ambient and high-temperature PBX 9502 SDT response and the results were compared to the physically measured results. It was found that π-SURF works in ambient cases. At high-temperature, however, it was determined that not enough information is known about hot spot formation to use the π-SURF model for high-temperature scenarios.
Highly enriched fuel contains large quantities of ²³⁵U; Burned fuel may contain large quantities of ²³⁹Pu; Reprocessing is the major threat (discussed at length later), but we need to ensure the amount of plutonium going to the reprocessing plant is what we believe it to be; All nuclear material needs to be accounted for (material accountancy); There may be a loss of continuity of knowledge in which case fuel needs to be measured to determine how much plutonium and uranium it contains.