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At least 1,783 records · Page 99
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Milestone 1.2.9: Radiolytic Gas Generation Measurements from Helium Backfilled Samples of AA1100 and AA6061 Coupons

Nearly 18 metric tons of aluminum-clad spent nuclear fuel (ASNF) is safely managed by the U.S. Department of Energy (DOE). These assemblies are currently in interim storage, with the intention of extended storage (>50 years) until final disposal. Strategies for the continued safe storage of this material are under evaluation, of which a key criterion is the extent of molecular hydrogen gas (H2) formation from the radiolysis of hydrated (oxy)hydroxide aluminum corrosion layers arising from in-reactor and wet storage conditions. Radiation-induced H2 formation has the potential to compromise cladding and storage canister integrity, in addition to promoting the formation of unfavorable gaseous environments. Consequently, understanding this radiation-induced phenomenon is essential for the development of predictive modeling capabilities to support technical considerations and the identification of radiation related challenges for the extended storage of ASNF. Here, we report radiolytic H2 yields (G-values, G(H2)) from the gamma irradiation of ‘pristine’ and pre-corroded aluminum coupons in helium (He) environments as a function of alloy composition (AA1100 and AA6061), relative humidity, and absorbed gamma dose. Measured yields were lower than corresponding values reported for argon environments, a positive result for proposed extended dry storage strategies that would employ helium as a backfill gas. Interestingly, the presented G(H2)He values are comparable to those previously measured in nitrogen environments, suggesting a He mediated H2 inhibition process, attributed here to Penning ionization.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Situational Awareness of Grid Anomalies (SAGA)

The modern power industry becomes more vulnerable to cyber events due to the growing interconnectivity, interdependence, and complexity of the electric power grid. High-fidelity modeling and simulation tools that support the preventative risk analysis on potential cyber-relevant events is essential for ensuring the situational awareness of the system operator as it provides an inexpensive and risk-free environment to test the system responses under various cyber-relevant events and hereby can support research on cyber anomaly detection, optimal protective resource allocation, and mitigation measures. In this webinar, we will share NREL's cybersecurity research capabilities by highlighting the development of a scalable cyber-physical event test bed and demonstration with real hardware in the loop. The developed cyber-physical event test bed is backboned by an integrated transmission, distribution, and communication dynamic co-simulation framework and a plug-and-play cyber event generation module. It is designed to be modular and compatible with parallel computing, and thereby supports large-scale system simulations at an affordable computation cost. The test bed can capture millisecond-to-minutes dynamic frequency and voltage responses under cyber events from the bulk transmission system to the active distribution systems and distributed energy resources at the grid edge.

co-simulation↗
DOE OSTI2015

Linear Vlasov Solver For Microbunching Gain Estimation With Inclusion of CSR, LSC And Geometric Impedances

As is known, microbunching instability (MBI) has been one of the most challenging issues in designs of magnetic chicanes for short-wavelength free-electron lasers or linear colliders, as well as those of transport lines for recirculating or energy recovery linac machines. To more accurately quantify MBI in a single-pass system and for more complete analyses, we further extend and continue to increase the capabilities of our previously developed linear Vlasov solver [1] to incorporate more relevant impedance models into the code, including transient and steady-state free-space and/or shielding coherent synchrotron radiation (CSR) impedances, the longitudinal space charge (LSC) impedances, and the linac geometric impedances with extension of the existing formulation to include beam acceleration [2]. Then, we directly solve the linearized Vlasov equation numerically for microbunching gain amplification factor. In this study we apply this code to a beamline lattice of transport arc [3] following an upstream linac section. The resultant gain functions and spectra are presented here, and some results are compared with particle tracking simulation by ELEGANT [4]. We also discuss some underlying physics with inclusion of these collective effects and the limitation of the existing formulation. It is anticipated that this more thorough analysis can further improve the understanding of MBI mechanisms and shed light on how to suppress or compensate MBI effects in lattice designs.

Tsai, C. -Y.↗
DOE OSTI2012

Equilibrium cycle pin by pin transport depletion calculations with DeCART

As the Advanced Fuel Cycle Initiative (AFCI) program has matured it has become more important to utilize more advanced simulation methods. The work reported here was performed as part of the AFCI fellowship program to develop and demonstrate the capability of performing high fidelity equilibrium cycle calculations. As part of the work here, a new multi-cycle analysis capability was implemented in the DeCART code which included modifying the depletion modules to perform nuclide decay calculations, implementing an assembly shuffling pattern description, and modifying iteration schemes. During the work, stability issues were uncovered with respect to converging simultaneously the neutron flux, isotopics, and fluid density and temperature distributions in 3-D. Relaxation factors were implemented which considerably improved the stability of the convergence. To demonstrate the capability two core designs were utilized, a reference UOX core and a CORAIL core. Full core equilibrium cycle calculations were performed on both cores and the discharge isotopics were compared. From this comparison it was noted that the improved modeling capability was not drastically different in its prediction of the discharge isotopics when compared to 2-D single assembly or 2-D core models. For fissile isotopes such as U-235, Pu-239, and Pu-241 the relative differences were 1.91%, 1.88%, and 0.59%), respectively. While this difference may not seem large it translates to mass differences on the order of tens of grams per assembly, which may be significant for the purposes of accounting of special nuclear material. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2012

Stakeholder Engagement on the Environmental Impact Statement for the Disposal of Greater-Than-Class C Low-Level Radioactive Waste -12565

The Department of Energy's (DOE) Office of Disposal Operations is responsible for developing a permanent disposal capability for a small volume, but highly radioactive, class of commercial low-level radioactive waste, known as Greater-Than-Class C (GTCC) low-level radioactive waste. DOE has issued a draft environmental impact statement (EIS) and will be completing a final EIS under the National Environmental Policy Act (NEPA) that evaluates a range of disposal alternatives. Like other classes of radioactive waste, proposing and evaluating disposal options for GTCC waste is highly controversial, presents local and national impacts, and generates passionate views from stakeholders. Recent national and international events, such as the cancellation of the Yucca Mountain project and the Fukushima Daiichi nuclear accident, have heighten stakeholder awareness of everything nuclear, including disposal of radioactive waste. With these challenges, the Office of Disposal Operations recognizes that informed decision-making that will result from stakeholder engagement and participation is critical to the success of the GTCC EIS project. This paper discusses the approach used by the Office of Disposal Operations to engage stakeholders on the GTCC EIS project, provides advice based on our experiences, and proffers some ideas for future engagements in today's open, always connected cyber environment. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Overview of the DOE nuclear fuels storage and transportation planning project - 15444

The US Department of Energy (DOE) Office of Nuclear Energy is conducting planning activities within the Nuclear Fuels Storage and Transportation Planning Project (NFST) to lay the groundwork for implementing interim storage, including associated transportation, per the Administration's Strategy for the Management and Disposal of Used Nuclear Fuel and High-Level Radioactive Waste, and to develop a foundation for a new nuclear waste management organization. The purpose of the NFST is to make progress on this important national issue within existing legislative and budgetary authorizations. The objective of the NFST is to develop and begin implementation of an integrated plan to (1) implement interim storage; (2) improve the overall integration of storage as a planned part of the waste management system; (3) prepare for the large-scale transportation of spent nuclear fuel and high-level radioactive waste, with an initial focus on removing SNF from the shutdown reactor sites; and (4) develop foundational information, resources, and capabilities needed to support the aforementioned objectives and future implementation decisions and actions. An over-arching goal is to develop options for decision-makers on the design of an integrated waste management system. The planning activities are divided into four major topical areas: (1) Consent-Based Siting, (2) Storage, (3) Transportation, and (4) Strategic Crosscuts. This paper provides an overview of the NFST and its activities. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Application of the FW-CADIS variance reduction method to calculate a precise N-flux distribution for the FRJ-2 research reactor - 15603

In order to avoid unnecessary radiation exposure and to minimize the radioactive waste and respectively cost by the decommissioning of nuclear facilities, the radiological characteristics and the activity atlases are required. Therefore, a significant step is the accurate determination of the neutron fluence distribution resulting from the operation of a reactor. For this purpose, computer codes based on the Monte-Carlo method are employed because of the flexibility in the modelling of the complex structures and physical processes. In the scope of the research project founded by the German Federal Ministry of Education and Research (BMBF), and implemented by the Institute of Nuclear Engineering and Technology Transfer (NET) -RWTH Aachen, sophisticated simulation tools are developed, which have the capability to cover the range of demands for activity and dose rate distribution using the example of the German research reactor FRJ-2. Due to the complex geometry of FRJ-2, which consists of different structures and configuration, the MCNP5 Monte Carlo Code is the optimal method for a precise neutron transport simulation. This work presents a method to achieve a precise N-Flux distribution for the FRJ-2 research reactor using hybrid deterministic Monte Carlo method. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

A New Safeguards Technique for Spent Fuel Verification in Dry Storage by Using He-4 Detectors - 18262

It is demanded to find key issues and critical paths for verifying and monitoring a spent nuclear fuel cask or storage with a purpose of non-proliferation of nuclear weapon. However, unfortunately there are no reliable methods to verify the containment in a spent nuclear fuel cask or storage. Therefore, research and development (R and D) has been continuously required to develop new and alternative technologies for searching and verifying undeclared nuclear materials, activities, and facilities. Therefore, the present authors have developed a new safeguards technique of passively scanning a spent fuel cask or storage using pressurized He-4 scintillation neutron detectors. A new approach is to quickly verify content in a spent nuclear fuel cask or presence of all special nuclear materials in unknown packages by comparing experimental and computational results. For that, the present authors have developed a new algorithm and user-interface coupled ORIGEN-ARP and MCNP codes, and the prototype safeguards apparatus employing the array of He-4 fast neutron detectors has been designed, built, and tested. The feasibility test of this new apparatus has been performed with Cf-252 neutron sources and the laboratory scale model cask, minimized by a factor of ten compared to the actual dimension of a KN-21 cask. This technique has several advantages over current methods based on neutron and gamma detection; (1) incident neutron energy information is preserved, (2) disturbance of gamma-ray is excellently rejected (discriminated), and (3) much higher neutron counts and operational cost and space-effectiveness are expected since no moderator is required for fast neutrons. The final goal of this study will (1) conduct a prototype instrument and employ it to monitor a nuclear spent fuel cask or storage at a commercial nuclear power reactor facilities, (2) use spectral-specific measurement data to show proof of concept for measurable data successfully converted to quantifiable signatures, such as diversion/removal of fuel, and maintenance of fuel and cask integrity of fuel, and (3) develop a cask imaging capability. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Particle Loading Dynamics of SRNL Electrostatic Particle Collectors - 19398

The Department of Energy is interested in decontamination methods and tools for the removal of airborne radioactive particulate from facilities prior to decommissioning. Electrostatic particle collectors (EPCs) have historically been used industrially to scrub particles from air streams for large scale operations, and Savannah River National Laboratory (SRNL) researchers have expanded on the fundamental collection capabilities of EPCs to develop unique samplers focused on particulate effluent collection. One distinct advantage of an electrostatic particle collection over filtration or inertial impaction-based methods is the low pressure drop associated with prolonged use of EPCs. Electrostatic particle collectors previously developed by SRNL have proven effective in the collection of atmospheric aerosols in multiple field trials, and their applicability as a decontamination method for airborne particulates. Initial experiments using aerosolized NaCl were performed to determine EPC collection efficiencies, the times required to achieve a desired particle loading, and the size distribution of collected particulates. The amount of NaCl collected on Si substrates was found to increase linearly with time (∼ 2 mg per hour) and showed little sign of change after 24 hours of collection. Experiments showed that NaCl, or a similar aerosol, would likely continue to collect unperturbed until physical limitations within the EPC are reached. Collection efficiencies (i.e., the number of particles collected vs. the number of particles entering the EPC) were calculated independently using an assessment scheme based on Particle Depletion Dynamics (PDD) and by Computer Controlled Scanning Electron Microscope (CCSEM) analysis of collection substrates for a range of particle sizes. For the ACE 2.0 with a corona voltage of 15 kV, collection efficiencies were determined using PDD to be 54, 29, and 13% for the flow rates 100, 300, and 490 L/min respectively. While CCSEM data suggests a very high collection efficiency for the MiniACE, the static sampling rate of 28.1 L/min (1 ft{sup 3}/min) was found to be too low volume for PDD to provide statistically meaningful data. Number density maps of NaCl particles detected via CCSEM revealed that particles are preferentially collected near the EPC inlet (i.e., opposite the direction of airflow) when using slower flow rates. Particles collected using higher flow rates (e.g., 300 and 490 L/min) were collected more evenly across the substrate. When segregated by size, smaller (e.g., 200-500 nm) particles are collected evenly across the collection substrates. As particle sizes increase they are collected preferentially near the EPC inlet, but not in sufficient quantity to obstruct airflow and hinder long-term operations. Subsequent deployment of the SRNL developed system into plutonium-238 contaminated hot cells will be performed at Savannah River Site Building 235-F. Presented in this work are the testing and considerations utilized by SRNL to show this technique as a viable means of rapidly decontaminating airborne contaminated areas. (authors)

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

Dry Canister Storage System Inspection and Robotic Delivery System Development

EPRI is working to develop and demonstrate technologies capable of inspecting welded stainless steel canisters used in dry cask storage systems in situ, without the need to remove them from their concrete casks. This involves the coupling of specialized cameras and inspection devices with small remotely operated vehicles (ROVs). The objective is to demonstrate the capability to identify any presence of (or precursors to) stress corrosion cracking (SCC) and other anomalies that may require additional investigation. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Nuclear Science User Facilities Irradiation Capabilities at Oak Ridge National Laboratory

The Nuclear Science User Facilities (NSUF) within the Department of Energy (DOE) Office of Nuclear Energy offer researchers the opportunity to access world-class nuclear facilities at no cost to the user. Oak Ridge National Laboratory (ORNL) offers users access to the High Flux Isotope Reactor (HFIR) in addition to a wide variety of post-irradiation examination facilities. The ORNL irradiation engineering team has compiled a large number of successful designs for irradiating nuclear fuel and material specimens. NSUF users can leverage these existing designs to significantly reduce the time, cost, and risk of failure when designing new irradiation experiments. This work summarizes some of the irradiation experiment designs and capabilities that have been developed at ORNL in the hope that this information will help improve future NSUF proposals and inspire new ideas for irradiations that can be performed in the HFIR.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2024

Medium Voltage Power Electronics Enabling DER and Increasing Climate Resiliency

As renewables grow to meet both increased decarbonization and electrification goals, functionality such as grid-forming capability needs to be developed. Medium-voltage power electronic-enabled interfaces for renewables and as new devices within the grid themselves are an ideal platform for implementing these functionalities.

decarbonization↗
DOE OSTI2024

Understanding the Chemical Complexity of Multicomponent Systems: Uranium Polyoxometalates as Nanosorbents

The overarching objective of this project was to develop a molecular-scale understanding of chemical interactions of the transuranic (TRU) elements with uranyl-based polyoxometalate nanoclusters (UPOMs). The specific goals that supported this overarching objective were to: (i) quantify TRU interactions with UPOMs as a function of TRU, carbonate, and UPOM concentration, pH, and temperature; (ii) examine the molecular-level bonding environment of TRU-UPOM complexes; and (iii) develop a rate expression capable of describing the sorption and reduction of TRU by UPOMs. The published literature suggests several potential interactions can occur in TRU-UPOM systems: (i) encapsulation of TRU and coordination with the internal ‘-yl’ oxygens of the UPOM, (ii) coordination of TRU with the external ‘-yl’ oxygens of the UPOM, and (iii) coordination of TRU with the bridging ligands (e.g., peroxo, hydroxo, oxalate) of the UPOM. The latter two may induce aggregation of the UPOMs. The concept of encapsulation is demonstrated by the X-ray diffraction structure of crystallized U 20 , which reveals a Na + cation under each pentagonal face (Sigmon et al., 2009). Computational modeling shows that, while the negative charge of U 20 is spread among all the oxygen atoms, the internal ‘-yl’ oxygens host the most negative charge (Miro and Bo, 2012). This negative charge is reduced through the complexation of the templating sodium ions in the interior of the UPOM. Furthermore, Nyman et al. (2011) shows that cesium can exit through the pentagonal window of U 28 in the aqueous phase, suggesting that the TRU elements, which are smaller than cesium, may be capable of entering a UPOM through these windows in an exchange reaction. Under this project, we focused on hafnium, neptunium, and plutonium interactions with UPOMs.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

Resilient Communications LDRD Poster

This poster is for the LDRD Poster Session held at INL. The intent is to highlight the intent of the project which was to develop a resilient communication capability for the WSComm waveform. The poster shows notional pictures of communications being inhibited by a low power transmitter such as one found in modern drones. It then highlights interference tolerance performance and notionally shows that replay attacks may impede the signal. By implementing Transmission Security (TRANSEC), one can protect the waveform from such attacks.

97 - MATHEMATICS AND COMPUTING↗
DOE OSTI2020

Development of FRET clusters for CBRN Detection

Advanced sensor capabilities for the simultaneous on-site detection of specific chemical, biological, and radiological/nuclear (CBRN) threats is important to significantly limit the risk of exposure to personnel and allow the rapid collection of essential scientific data and critical evidence. Commercially available sensor capabilities are generally complex, and/or require highly specific and ultra-sensitive methods that are often power demanding or require offsite post-analysis for positive detection, leaving personnel vulnerable. The goal of this project is to develop a portable sensor capable of simultaneously detecting CBRN signatures using a multiplexed Förster Resonance Energy Transfer (FRET) based sensor. FRET sensors are tailorable, specific, and highly dependent on the donor-acceptor distance. In this project, nanoparticles were functionalized with aptamers that were designed for the detection of methylphosphonate, a sarin metabolite. FRET was measured between quantum dot donors and dye and metal nanoparticle acceptors using optical spectroscopy.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2018

Electrolytic Oxide Reduction of Plutonium Oxide Surrogates

Our research team has investigated electrolytic oxide reduction (EOR) as an improved metal production process versus the currently employed multiple cycle direct oxide reduction (MCDOR) process for the conversion of plutonium oxide to plutonium metal. Inherent advantages in safety, waste generation, efficiency, and operational ease make EOR an attractive alternative to traditional metal production practices. Phase I of the project consisted of the construction of a prototype electrochemical cell, and proof of concept experiments towards the reduction of SnO 2 and CeO 2 compounds. Phase II of the project was focused on the optimization of the cerium system in preparation for future plutonium EOR experiments. We observed the electrolytic reduction of cerium oxide resulting in mixed degrees of success, and discovered this was a result of parasitic side reactions and partial reduction. We employed cyclic voltammetry (CV) to identify the products of these side reactions and characterize partially reduced species. We also observed that, when metal was successfully produced by EOR, a large amount of passed charge was required. We concluded that this observation was due to several inefficiencies of the process relating to the reduction mechanism (e.g. inefficient use of cathodically produced calcium). We used our CV results to guide our optimization of the EOR of CeO 2 by refining our electrochemical method, cell geometry, and materials of construction. Finally, we developed a next generation cell, worked to establish a new molten salt electrochemical capability in the Plutonium Facility, and completed a strategy for plutonium experiments. Our electrochemical method to produce plutonium metal clearly supports the core mission of the laboratory. Furthermore, this project has allowed for the development of capabilities that will provide valuable data to programs interested in characterization and detection, as well as science of signatures. Additionally, establishing this capability in the plutonium facility will facilitate future safeguard studies that can assist with safeguard development in molten salt reprocessing flowsheets, and molten salt reactor designs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Effects of Reactive Power on Photovoltaic Inverter Reliability and Lifetime

This paper performs research on predicting Photovoltaic (PV) inverters reliability and lifetime based on thermal cycling. Thermal cycling is considered the most important stressors in an inverter system. In order to achieve this, a detailed electro-thermal model of the PV inverter will be developed along with their controllers capable of providing voltage support through reactive power. An in-house inverter was built, and a PV inverter model was developed to match the physical inverter. The PV inverter electrothermal model was validated for different ambient temperatures to match the in-house inverter hardware. The in-house inverter was placed inside a thermal chamber to emulate different ambient temperatures and their losses and temperature rises within the system were measured. After the validation of the model, a reduced order model of the inverter will be implemented to translate the mission profile of ambient temperature and solar irradiance into load profile of junction temperatures of the switches. The junction temperature data will be used to identify the reliability indices and hence predict the useful lifetime of the inverter system. Along with the model to predict useful lifetime of the system, the impact of reactive power on the overall reliability of the system will be studied. The key observation in this paper shows that lifetime of the inverter decreases as the operating power factor moves away from unity.

14 SOLAR ENERGY↗