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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Safety Aspects of Dry Spent Fuel Storage and Spent Fuel Management - 13559

Dry storage systems are characterized by passive and inherent safety systems ensuring safety even in case of severe incidents or accidents. After the events of Fukushima, the advantages of such passively and inherently safe dry storage systems have become more and more obvious. As with the storage of all radioactive materials, the storage of spent nuclear fuel (SF) and high-level radioactive waste (HLW) must conform to safety requirements. Following safety aspects must be achieved throughout the storage period: - safe enclosure of radioactive materials, - safe removal of decay heat, - securing nuclear criticality safety, - avoidance of unnecessary radiation exposure. The implementation of these safety requirements can be achieved by dry storage of SF and HLW in casks as well as in other systems such as dry vault storage systems or spent fuel pools, where the latter is neither a dry nor a passive system. Furthermore, transport capability must be guaranteed during and after storage as well as limitation and control of radiation exposure. The safe enclosure of radioactive materials in dry storage casks can be achieved by a double-lid sealing system with surveillance of the sealing system. The safe removal of decay heat must be ensured by the design of the storage containers and the storage facility. The safe confinement of radioactive inventory has to be ensured by mechanical integrity of fuel assembly structures. This is guaranteed, e.g. by maintaining the mechanical integrity of the fuel rods or by additional safety measures for defective fuel rods. In order to ensure nuclear critically safety, possible effects of accidents have also to be taken into consideration. In case of dry storage it might be necessary to exclude the re-positioning of fissile material inside the container and/or neutron moderator exclusion might be taken into account. Unnecessary radiation exposure can be avoided by the cask or canister vault system itself. In Germany dry storage of SF in casks fulfills both transport and storage requirements. Mostly, storage facilities are designed as concrete buildings above the ground, but due to regional constraints, one storage facility has also been built as a rock tunnel. The decay heat is always removed by natural air flow; further technical equipment is not needed. The removal of decay heat and shielding had been modeled and calculated by state-of-the-art computer codes before such a facility has been built. TueV and BAM present their long experience in the licensing process for sites and casks and inform about spent nuclear fuel management and issues concerning dry storage of spent nuclear fuel. Different storage systems and facilities in Germany, Europe and world-wide are compared with respect to the safety aspects mentioned above. Initial points are the safety issues of wet storage of SF, and it is shown how dry storage systems can ensure the compliance with the mentioned safety criteria over a long storage period. The German storage concept for dry storage of SF and HLW is presented and discussed. Exemplarily, the process of licensing, erection and operation of selected German dry storage facilities is presented. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Stochastic Adaptive Droop Control in Frequency Regulation of Power Systems With Intermittent Generators

Modern power systems (MPSs), including microgrids (MGs), are increasingly incorporating multiple renewable energy sources (RESs) such as wind and solar power, as well as battery storage and controllable loads. While environmentally beneficial, these sources pose challenges for control and management due to their intermittent and stochastic nature, especially in maintaining frequency stability with multiple interconnected generators of varying capacities. Traditional droop control methods are effective in systems with generators that are dispatchable and have fixed generation capacities, but they fall short when applied to systems with RESs, where generation capacities are dynamic and affected by unpredictable environmental conditions. To address these challenges, this paper introduces a novel stochastic adaptive droop control (SADC) method for load frequency control (LFC). The proposed method adapts droop coefficients in real time, based on the measured stochastic data of power generation capacities, enabling more effective frequency regulation in systems with variable and intermittent power generation. Unlike traditional adaptive control methods, which assume constant or slowly-varying system parameters, this approach accounts for stochastic processes by modeling them as Markov chains, enabling robust performance under highly dynamic and unpredictable conditions. The key contributions of this work include the development of real-time droop coefficient adaptation algorithms, derivation of their stability and convergence properties, and the demonstration of the advantages of the method through simulations. Case studies highlight the improved performance of frequency regulation, particularly in addressing the impact of stochastic weather conditions and the benefits of reducing dependence on battery reserves in dealing with intermittency of RESs. Finally, this paper provides a comprehensive analysis of the theoretical foundations of the method, as well as practical implementation insights for future power systems with high penetration of RESs.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS2002

National Aeronautics and Space Administration Fiscal Year 2001 Accountability Report

The National Aeronautics and Space Administration (NASA) is an independent Agency established to plan and manage the future of the Nation's civil aeronautics and space program. This Accountability Report covers Federal Fiscal Year (FY) 2001 (October 1, 2000, through September 30, 2001), with discussion of some subsequent events. The Report contains an overview addressing the Agency's critical programs and financial performance and includes highlights of performance organized by goals and objectives of the Enterprises and Crosscutting Processes. The Report also summarizes NASA's stewardship over budget and financial resources, including audited financial statements and footnotes. The financial statements reflect an overall position of offices and activities, including assets and liabilities, as well as results of operations, pursuant to requirements of Federal law (31 U.S.C. 3515(b)). The auditor's opinions on NASA's financial statements, reports on internal controls, and compliance with laws and regulations are included in this report.

Source record↗
NASA NTRS2001

National Aeronautics and Space Administration FY 2001 Accountability Report

The National Aeronautics and Space Administration (NASA) is an independent Agency established to plan and manage the future of the Nation's civil aeronautics and space program. This Accountability Report covers Federal Fiscal Year (FY) 2001 (October 1, 2000, through September 30, 2001), with discussion of some subsequent events The Report contains an overview addressing the Agency's critical programs and financial performance and includes highlights of performance organized by goals and objectives of the Enterprises and Crosscutting Processes. The Report also summarizes NASA's stewardship over budget and financial resources, including audited financial statements and footnotes. The financial statements reflect an overall position of offices and activities, including assets and liabilities, as well as results of operations, pursuant to requirements of Federal law (31 U.S.C. 3515(b)). The auditor's opinions on NASA's financial statements, reports on internal controls, and compliance with laws and regulations are included in this Report.

Source record↗
DOE OSTI2015

Storage and concentration of plutonium and uranium solutions in LES 401 hot cell (ATALANTE) - criticality safety considerations - 14414

ATALANTE, located in Marcoule, is one of the main nuclear facilities of the French CEA (Atomic Energy and Alternative Energies Commission). The LES 401 hot cell was built in the 1980's and, since then, has been operating only with low masses of fissile material. As part of the management optimization for purified Uranium and Plutonium solutions ('Fin U Pu' Project), the new functions provided in LES 401 are now expected to be the following: - Reception of Uranium and Plutonium solutions, - Concentration of these solutions, - Storage of the concentrates and distillates. From the criticality safety point of view, the equipment was originally designed in safe geometry for Plutonium Nitrate, considering only a 2.5 cm -thick water reflector. However, the new criticality safety case had to take into account the following points: - Reception of not only Plutonium solutions, but also highly enriched Uranium solutions, - Considering flood risk as a possible contingency, - Considering precipitation as a possible contingency. These more conservative assumptions have meant introducing a mass limit for the cell, in addition to the geometry control mode. For the equipment containing very low concentrations of fissile material in normal operation, it was necessary, using the double contingency principle, to take a concentration limit into account in the specific situation of water flooding the cell. Finally, given the mass and geometry control mode, it was necessary to perform all the calculations with both fissile media (Plutonium and Uranium), as it was found that depending on the selected mass, geometry, and reflection conditions, the most penalizing media is not always the same. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Effects of aqueous uranyl speciation on the kinetics of microbial uranium reduction

The ability to predict the success of the microbial reduction of soluble U(VI) to highly insoluble U(IV) as an in situ bioremediation strategy is complicated by the wide range of geochemical conditions at contaminated sites and the strong influence of aqueous uranyl speciation on the bioavailability and toxicity of U(VI) to metal-reducing bacteria. In order to determine the effects of aqueous uranyl speciation on uranium bioreduction kinetics, incubations and viability assays with Shewanella putrefaciens strain 200 were conducted over a range of pH and dissolved inorganic carbon (DIC), Ca 2+ , and Mg 2+ concentrations. A speciation-dependent kinetic model was developed to reproduce the observed time series of total dissolved uranium concentration over the range of geochemical conditions tested. The kinetic model yielded the highest rate constant for the reduction of uranyl non-carbonate species (i.e., the ‘free’ hydrated uranyl ion, uranyl hydroxides, and other minor uranyl complexes), indicating that they represent the most readily reducible fraction of U(VI) despite being the least abundant uranyl species in solution. In the presence of DIC, Ca 2+ , and Mg 2+ is suppressed during the formation of more bioavailable uranyl non-carbonate species and resulted in slower bioreduction rates. At high concentrations of bioavailable U(VI), however, uranium toxicity to S. putrefaciens inhibited bioreduction, and viability assays confirmed that the concentration of non-carbonate uranyl species best predicts the degree of toxicity. The effect of uranium toxicity was accounted for by incorporating the free ion activity model of metal toxicity into the bioreduction rate law. These results demonstrate that, in the absence of competing terminal electron acceptors, uranium bioreduction kinetics can be predicted over a wide range of geochemical conditions based on the bioavailability and toxicity imparted on U(VI) by solution composition. Finally, these findings also imply that the concentration of uranyl non-carbonate species, despite being extremely low, is a determining factor controlling uranium bioreduction at contaminated sites.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2015

Evaluating Coastal Landscape Response to Sea-Level Rise in the Northeastern United States - Approach and Methods

The U.S. Geological Survey is examining effects of future sea-level rise on the coastal landscape from Maine to Virginia by producing spatially explicit, probabilistic predictions using sea-level projections, vertical land movement rates (due to isostacy), elevation data, and land-cover data. Sea-level-rise scenarios used as model inputs are generated by using multiple sources of information, including Coupled Model Intercomparison Project Phase 5 models following representative concentration pathways 4.5 and 8.5 in the Intergovernmental Panel on Climate Change Fifth Assessment Report. A Bayesian network is used to develop a predictive coastal response model that integrates the sea-level, elevation, and land-cover data with assigned probabilities that account for interactions with coastal geomorphology as well as the corresponding ecological and societal systems it supports. The effects of sea-level rise are presented as (1) level of landscape submergence and (2) coastal response type characterized as either static (that is, inundation) or dynamic (that is, landform or landscape change). Results are produced at a spatial scale of 30 meters for four decades (the 2020s, 2030s, 2050s, and 2080s). The probabilistic predictions can be applied to landscape management decisions based on sea-level-rise effects as well as on assessments of the prediction uncertainty and need for improved data or fundamental understanding. This report describes the methods used to produce predictions, including information on input datasets; the modeling approach; model outputs; data-quality-control procedures; and information on how to access the data and metadata online.

terrain↗
DOE OSTI2015

Establishing no credible risk of inadvertent criticality for the K-25 demolition project - 14310

Demolition of the K-25 Gaseous Diffusion Plant required establishing a non-credible risk of inadvertent criticality because a Criticality Accident Alarm System (CAAS) could not be reliably maintained operable as the building was being torn down. Preparation for, and demolition of, the facility was a multi-year long effort with significant changes in approach. The most significant change was to demolish the facility with as much of the process gas equipment and piping left in the facility as possible, rather than removing all process gas equipment and piping from the facility prior to demolishing the building structure only. The contractor had to adapt their approach to accommodate these changes. The normal approach to demolition was to remove all process gas equipment and piping prior to demolition, using Nuclear Criticality Safety (NCS) controls based on the double contingency principle, while CAAS coverage was intact. Then, the building structure was demolished with no requirement for a CAAS. This was the method used to demolish the K-33 Building, for example. In the case of K-25 demolition, all equipment and piping that met the Environmental Management Waste Management Facility (EMWMF) disposal cell Waste Acceptance Criteria (WAC) was left in the building and removed as part of the building demolition process. This resulted in significant quantities of fissionable material remaining in the building and being handled during demolition. The NCS Organization worked closely with several groups during preparation activities. A Data Management organization was established to specifically identify every piece of process gas equipment and piping in the facility so that it could be accounted for and characterized. Deactivation and Decommissioning (D and D) personnel conducted internal visual inspections, by remote camera, of all process gas equipment and piping larger than 3' diameter, to reveal any large deposits that would require removal. Non-Destructive Assay (NDA) of the vast majority of equipment and piping was required to quantify the amount of fissionable material remaining. Finally, all process gas equipment and piping larger than 3'' diameter was internally filled with foam, which was credited by NCS with immobilizing the remaining fissionable material such that large migration and accumulation could not occur during demolition activities. NCS personnel worked closely with all of these groups in order to acquire the data and information needed to establish a non-credible risk of inadvertent criticality during building demolition. Good communication and a close working relationship between NCS, the various D and D/characterization personnel, and the Department of Energy (DOE) ensured the success of the modified approach to building demolition. The same successful approach is currently underway in the K-27 Building as well. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Understanding and Controlling Cesium Loading on Crystalline Silicotitanate - 19601

Savannah River Remediation (SRR) contracted with Westinghouse Electric Corporation (WEC), Columbia Energy and Environmental Services (CEES), to build and deliver a modular ion exchange process that will be used to remove radioactive cesium from dissolved salt solution contained in Tank 10 at the Savannah River Site (SRS). The resulting decontaminated salt solution will be sent to Tank 11 and then to Tank 50 for final disposition in grout at the Saltstone facility. At the end of processing, the loaded ion exchange (IX) columns are drained, rinsed, and dried. The IX columns are removed from the modular unit and stored at Interim Safe Storage (ISS). This ion exchange process is called the Tank Closure Cesium Removal (TCCR) system. The TCCR system consists of several unit operations and process monitoring capability housed within three modular units. The first modular unit contains the process control computer, the second modular unit contains the main process equipment (two prefilters, four IX columns, and resin trap (post filtration)), and the third modular unit is the ventilation system. The main unit operations of the TCCR system are filtration, ion exchange, and ventilation. The ion exchange media utilized is a form of inorganic Crystalline Silicotitanate (CST), IONSIV{sup TM} R9120-B supplied by UOP Honeywell. CST has a high selectivity for cesium (Cs) and has some affinity for other Group IA alkali metals on the periodic chart (hydrogen, lithium, sodium, potassium, rubidium, and francium). CST has also been shown to have affinity for strontium and actinides. Cesium loading on the CST is dependent on many factors including chemical composition (cations and anions), temperature, and pH of the salt solution. The actual amount of Cs loaded onto an IX column is dependent on the factors above along with the salt solution volume fed to the IX column. Because of CST's high selectivity for Cs, the Cs-137 equilibrium loading can contribute enough decay heat to result in an ion exchange column boiling event under no flow conditions in the IX column. The boiling event under no flow is a safety concern that must be prevented from occurring. To prevent boiling of the column under no flow conditions, the Cs-137 equilibrium loading must be determined and understood. Several methodologies were evaluated for performing the Cs-137 equilibrium loading determination for CST. After review of available research and development (R and D), batch equilibrium contact test data, and Zheng Anthony Miller (ZAM) model predictions for the salt solution chemistry in Tank 10, a methodology for determining the Cs-137 equilibrium loading on CST was selected. The methodology selected involves an in-tank batch equilibrium contact test performed in duplicate that considers additional corrections to account for anticipated operational evolutions. The in-tank batch equilibrium contact test utilizes ∼0.1 grams of CST secured in a slotted sample vial. The slotted sample vial design allows for salt solution to be in contact with the CST. The slotted sample vials containing the CST are submerged in Tank 10 and exposed to the salt solution for ten days. After ten days, the samples are retrieved and sent to the Savannah River National Laboratory (SRNL) for analysis of the Cs-137 equilibrium loading. Additional corrections are then made to the Cs-137 results to account for anticipated operational evolutions. Anticipated operational evolutions include external additions (water/caustic) to Tank 10 that result in a change to its chemical composition, tank temperature effects, departures from the laboratory testing (mixed vs. stagnant tank conditions), and IX column flushes. A description of the methodologies considered, feasibility of methodology deployment, and the down select process (benefits vs. risks) is discussed in this paper. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Predicting Ice Sheet and Climate Evolution at Extreme Scales

A main research objectives of PISCEES is the development of formal methods for quantifying uncertainties in ice sheet modeling. Uncertainties in simulating and projecting mass loss from the polar ice sheets arise primarily from initial conditions, surface and basal boundary conditions, and model parameters. In general terms, two main chains of uncertainty propagation may be identified: 1. inverse propagation of observation and/or prior onto posterior control variable uncertainties; 2. forward propagation of prior or posterior control variable uncertainties onto those of target output quantities of interest (e.g., climate indices or ice sheet mass loss). A related goal is the development of computationally efficient methods for producing initial conditions for an ice sheet that are close to available present-day observations and essentially free of artificial model drift, which is required in order to be useful for model projections (“initialization problem”). To be of maximum value, such optimal initial states should be accompanied by “useful” uncertainty estimates that account for the different sources of uncerainties, as well as the degree to which the optimum state is constrained by available observations. The PISCEES proposal outlined two approaches for quantifying uncertainties. The first targets the full exploration of the uncertainty in model projections with sampling-based methods and a workflow managed by DAKOTA (the main delivery vehicle for software developed under QUEST). This is feasible for low-dimensional problems, e.g., those with a handful of global parameters to be inferred. This approach can benefit from derivative/adjoint information, but it is not necessary, which is why it often referred to as “non-intrusive”. The second approach makes heavy use of derivative information from model adjoints to address quantifying uncertainty in high-dimensions (e.g., basal boundary conditions in ice sheet models). The use of local gradient, or Hessian information (i.e., second derivatives of the cost function), requires additional code development and implementation, and is thus often referred to as an “intrusive” approach. Within PISCEES, MIT has been tasked to develop methods for derivative-based UQ, the ”intrusive” approach discussed above. These methods rely on the availability of first (adjoint) and second (Hessian) derivative code, developed through intrusive methods such as algorithmic differentiation (AD). While representing a significant burden in terms of code development, derivative-baesd UQ is able to cope with very high-dimensional uncertainty spaces. That is, unlike sampling methods (all variations of Monte Carlo), calculational burden is independent of the dimension of the uncertainty space. This is a significant advantage for spatially distributed uncertainty fields, such as threedimensional initial conditions, three-dimensional parameter fields, or two-dimensional surface and basal boundary conditions. Importantly, uncertainty fields for ice sheet models generally fall into this category.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Lessons Learned from the Development of the DGR Konrad - 19619

The Federal Republic Germany builds the deep geological repository Konrad. The repository is suitable for low- and intermediate-level radioactive waste (LAW and MAW) and it is the first German repository site, which is not located in a salt geological formation. Konrad is a former iron ore mine in Salzgitter (in southeast Lower Saxony) with an active production time between 1961 and 1976. In 2007, the BGE started with the conversion of the mine infrastructure above and underground to build the repository while using the shafts and some roadways of the former mine. The experiences gained from ten years project progress with its complexities and difficulties can be used for similar repository projects in the future. The Konrad repository is designed for 303,000 m{sup 3} of LAW and MAW, which will be emplaced in chambers. The emplacement chambers are located outside of the existing mine, so an impairment by the old mine workings can be excluded. So far, the first area with emplacement chambers has been excavated. In order to be able to start repository operations in 2027, a wide range of work in building construction, civil engineering, shaft sinking and infrastructure development above and below ground has been necessary and will be completed in the next years. The main activities are focused on the Konrad 1 and 2 sites and the part of the infrastructure located in the future control area, which is used for repository operations. There are still many challenges to overcome in the Konrad repository project, although many processes have been put on the right track in recent years. Looking back on past activities and in the cautious preview, this paper gives some indications from which lessons can be drawn and should be applied to similar projects in the future. - Prefer small dimensions for the infrastructure, such as insets and roadway cross-section, and the appropriate machinery and handling equipment; - Detailed process planning for construction in existing infrastructure in the run-up to implementation; - Intensive communication with contracted partners on the preparation of planning documents for nuclear examination procedures and ensuring an excellent contract management; - Early start of the implementation planning for projects under nuclear law, taking into account the relevant boundary conditions; - Ensuring the support of the project by the local community and other stakeholders. Overall, the use of parts of the existing above and underground infrastructure for the construction of a new repository is more difficult than for a complete new construction. But using the shafts of an existing mine delivers the advantage of very good knowledge about the underground environment. In addition, the areas necessary for the construction and operation of the buildings and facilities are already available and secured and do not compete with other projects.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

Seasonal performance evaluation of zero-superheat active refrigerant charge control for variable-speed heat pumps

Heat pumps account for a significant portion of electricity consumption in buildings, making their energy efficiency a critical area of research. Control optimization is recognized as an effective approach for enhancing the efficiency of building HVAC systems. Specifically, since the efficiency of heat pumps increases with reduced superheat and the optimal refrigerant charge level varies with operating conditions, zero-superheat active charge control is a promising strategy to maximize the system’s COP. However, due to its complexity, this control strategy remains in the research phase and has only been tested under limited operating conditions. This paper proposes a methodology to evaluate the seasonal performance improvement of zero-superheat active charge control across a full range of heating conditions in buildings. The methodology includes the development of an optimal controller that utilizes an accumulator to store excess refrigerant and manages the active charge level at zero superheat through subcooling control, as well as the creation of a detailed physics-based heat pump model. Targeted a 3-ton variable-speed heat pump with R410A refrigerant, we selected ten U.S. cities representing different climate regions for seasonal performance evaluation. Our simulations indicate that, depending on the climate conditions, the optimal control strategy could achieve energy savings ranging from 5.8 % to 8.0 % over the entire heating season. These results suggest that zero-superheat active charge control, combined with coordinated compressor and fan speeds, could substantially improve the energy efficiency of heat pump systems while maintaining the required heating capacity.

Guo, Fangzhou↗
NASA NTRS1984

Langley's views on NEMS

The views of the Langley Research Center regarding the NASA Equipment Management System (EMS) are discussed. One of Langley's greatest concerns is with the reconciliation between NEMS and the General Ledger. Langley's accounting system tracks cost data to the penny level. NEMS deals in whole dollar amounts. Therefore, Langley has no way of reconciling the two. The only approach that is acceptable to Langley, unless requirements for reconciliation are changed, is for the NEMS files and the reports involved in the process be at the penny level. All other NEMS reports can remain whole dollars. Also to reconcile, Langley needs data to show the difference between the previous cost and the new cost for the month. On an input record, the adjustment amount is added to the cost and recorded as total amount. The adjusted cost is not captured. In order to establish a control between the prior months and the current month, a new field needs to be added to capture the adjusted cost (debits And credits). Langley has not reconciled the Equipment account with the General Ledger since February 1984. Problems with NEMS regular production runs cause concern. Production at Langley is run on the second and/or third shift. If a run(s) terminates and/or abends in a particular module, Langley must wait until the next day to resolve NEMS problems after consultation with Headquarters personnel. For a successful installation, Langley must have a good data base to convert to NEMS and users and the data processing staff must work together.

George, J. W.↗
DOE OSTI2015

Investigation of criticality safety control infraction data at a nuclear facility

Chemical and metallurgical operations involving plutonium and other nuclear materials account for most activities performed at the LANL's Plutonium Facility (PF-4). Here, the presence of large quantities of fissile materials in numerous forms at PF-4 makes it necessary to maintain an active criticality safety program. The LANL Nuclear Criticality Safety (NCS) Program provides guidance to enable efficient operations while ensuring prevention of criticality accidents in the handling, storing, processing and transportation of fissionable material at PF-4. In order to achieve and sustain lower criticality safety control infraction (CSCI) rates, PF-4 operations are continuously improved, through the use of Lean Manufacturing and Six Sigma (LSS) business practices. Employing LSS, statistically significant variations (trends) can be identified in PF-4 CSCI reports. In this study, trends have been identified in the NCS Program using the NCS Database. An output metric has been developed that measures ADPSM Management progress toward meeting its NCS objectives and goals. Using a Pareto Chart, the primary CSCI attributes have been determined in order of those requiring the most management support. Data generated from analysis of CSCI data help identify and reduce number of corresponding attributes. In-field monitoring of CSCI's contribute to an organization's scientific and technological excellence by providing information that can be used to improve criticality safety operation safety. This increases technical knowledge and augments operational safety.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2013

Targeted Health Assessment for Wastes Contained at the Niagara Falls Storage Site to Guide Planning for Remedial Action Alternatives - 13428

The U.S. Army Corps of Engineers (USACE) is evaluating potential remedial alternatives at the 191-acre Niagara Falls Storage Site (NFSS) in Lewiston, New York, under the Formerly Utilized Sites Remedial Action Program (FUSRAP). The Manhattan Engineer District (MED) and Atomic Energy Commission (AEC) brought radioactive wastes to the site during the 1940's and 1950's, and the U.S. Department of Energy (US DOE) consolidated these wastes into a 10-acre interim waste containment structure (IWCS) in the southwest portion of the site during the 1980's. The USACE is evaluating remedial alternatives for radioactive waste contained within the IWCS at the NFSS under the Feasibility Study phase of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) process. A preliminary evaluation of the IWCS has been conducted to assess potential airborne releases associated with uncovered wastes, particularly during waste excavation, as well as direct exposures to uncovered wastes. Key technical issues for this assessment include: (1) limitations in waste characterization data; (2) representative receptors and exposure routes; (3) estimates of contaminant emissions at an early stage of the evaluation process; (4) consideration of candidate meteorological data and air dispersion modeling approaches; and (5) estimates of health effects from potential exposures to both radionuclides and chemicals that account for recent updates of exposure and toxicity factors. Results of this preliminary health risk assessment indicate if the wastes were uncovered and someone stayed at the IWCS for a number of days to weeks, substantial doses and serious health effects could be incurred. Current controls prevent such exposures, and the controls that would be applied to protect onsite workers during remedial action at the IWCS would also effectively protect the public nearby. This evaluation provides framing context for the upcoming development and detailed evaluation of remedial alternatives for the IWCS. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Loss-of-Flow and Loss-of-Pressure Simulations of the BR2 Research Reactor with HEU and LEU Fuel

Belgian Reactor 2 (BR2) is a research and test reactor located in Mol, Belgium and is primarily used for radioisotope production and materials testing. The Materials Management and Minimization (M3) Reactor Conversion Program of the National Nuclear Security Administration (NNSA) is supporting the conversion of the BR2 reactor from Highly Enriched Uranium (HEU) fuel to Low Enriched Uranium (LEU) fuel. The reactor core of BR2 is located inside a pressure vessel that contains 79 channels in a hyperboloid configuration. The core configuration is highly variable as each channel can contain a fuel assembly, a control or regulating rod, an experimental device, or a beryllium or aluminum plug. Because of this variability, a representative core configuration, based on current reactor use, has been defined for the fuel conversion analyses. The code RELAP5/Mod 3.3 was used to perform the transient thermal-hydraulic safety analyses of the BR2 reactor to support reactor conversion. The input model has been modernized relative to that historically used at BR2 taking into account the best modeling practices developed by Argonne National Laboratory (ANL) and BR2 engineers.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2014

Toward Understanding the Effect of Low-Activity Waste Glass Composition on Sulfur Solubility

The concentration of sulfur in nuclear waste glass melter feed must be maintained below the point where salt accumulates on the melt surface. The allowable concentrations may range from 0.37 to over 2.05 weight percent (of SO3 on a calcined oxide basis). If the amount of sulfur exceeds its tolerance level a molten salt will accumulate and upset melter operations and potentially shorten melter useful life. Therefore relatively conservative limits have been placed on sulfur loading in melter feed which in-turn significantly impacts the amount of glass that will be produced, in particular at the Hanford site. Crucible-scale sulfur solubility data and scaled melter sulfur tolerance data have been collected on simulated Hanford waste glasses over the last 15 years. These data were compiled and analyzed. A model was developed to predict the solubility of SO3 in glass based on 312 individual glass compositions. This model was shown to well represent the data, accounting for over 80% of the variation in data and was well validated. The model was also found to accurately predict the tolerance for sulfur in melter feed based on 19 scaled melter tests. The model is appropriate for control of waste glass processing which includes uncertainty quantification. The model also gives quantitative estimates of component concentration effects on sulfur solubility. The components that most increase sulfur solubility are Li2O > V2O5 ≈ TiO2 < CaO < P2O5 ≈ ZnO. The components that most decrease sulfur solubility are Cl > Cr2O3 > SiO2 ≈ ZrO2 > Al2O3.

Borosilicate↗
DOE OSTI2021

Sensitivity Analysis of Occupant Preferences on Energy Usage in Residential Buildings: Preprint

Residential buildings, accounting for 37% of the total electricity consumption in the United States, are suitable for demand-side management (DSM) programs to support effective and economical operation of the power system. A home energy management system (HEMS) enables residential buildings to participate in such programs. It is important to account for occupant preferences in HEMS to ensure occupant satisfaction while participating in DSM programs. For example, people who prefer a higher thermal comfort level are likely to consume more energy. In this study, we used foresee™, a HEMS developed by the National Renewable Energy Lab (NREL), to perform a sensitivity analysis of occupant preferences with the following objectives: minimize utility cost, minimize carbon footprint, and maximize thermal comfort. To incorporate the preferences into the HEMS, the SMARTER method was used to derive a set of weighting factors for each objective. We performed week-long building energy simulations using a model of a home in Fort Collins, Colorado, where there is mandatory time-of-use electricity rate structure. The foreseeTM HEMS was used to control the home with six different sets of occupant preferences. The study shows that occupant preferences can have a significant impact and is important to consider when modeling residential buildings. Results show that the HEMS could achieve energy reduction ranging from 3% to 21%, cost savings ranging from 5% to 24%, and carbon emission reduction ranging from 3% to 21%, while maintaining a low thermal discomfort level ranging from 0.78 K-hour to 6.47 K-hour in a one-week period during winter. These outcomes quantify the impact of varying occupant preferences and will be useful for controlling the electrical grid and developing HEMS solutions.

carbon footprint↗