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Results for “RADIOACTIVE AEROSOLS”

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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Studying the impact of radioactive charging on the microphysical evolution and transport of radioactive aerosols with the TOMAS-RC v1 framework

We present that radioactive charging can significantly impact the way radioactive aerosols behave, and as a result their lifetime, but such effects are neglected in predictive model studies of radioactive plumes. The objective of this work is to determine the influence of radioactive charging on the vertical transport of radioactive aerosols in the atmosphere, through its effect on coagulation and deposition, as well as quantifying the impact of this charging on aerosol lifetime. The TwO-Moment Aerosol Sectional (TOMAS) microphysical model was extended to account for radioactive charging effects on coagulation in a computationally efficient way. The expanded model, TOMAS-RC (TOMAS with Radioactive Charging effects), was then used to simulate the microphysical evolution and deposition of radioactive aerosol (containing the isotopes 131 I and 137 Cs) in a number of idealized atmospheric transport experiments. Results indicate that radioactive charging can facilitate or suppress coagulation of radioactive aerosols, thus influencing the deposition patterns and total amount of radioactive aerosol mass available for long-range transport. Sensitivity simulations to uncertain parameters affirm the potential importance of radioactive charging effects. Lastly, an important finding is that charging of neutral, coarse mode aerosol from background radiation can reduce coagulation rates and extend its lifetime in the atmosphere by up to a factor of 2.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Radioactive aerosols training

An introduction to radioactive aerosols will be presented in this class. There will be a specific focus on transuranic materials, typical to those used in operations at Los Alamos. The uptake of radioactive aerosols is affected by the physical characteristics of the airborne material, the behavior of the aerosol in air (or gas), and the interaction of the material with the worker. Aerosol behavior in the radiological workplace will influence filtration, release control, and dose considerations. This course will review the basics of aerosol technology, distinguishing between the classical (Newtonian) and molecular (quantized) regimes. Particles from about 1 to 10 microns (diameter) are described by classical physics, but particles from about 0.01 to 0.3 microns must be understood through modern molecular theory (i.e. Einstein, 1905). The class will discuss relevant LANL accidents that involved aerosol releases from the years 1971, 1994, 2000, 2003 and 2005.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2015

Note: Real time optical sensing of alpha-radiation emitting radioactive aerosols based on solid state nuclear track detector

A sensitive radioactive aerosols sensor has been designed and developed. Its design guidance is based on the need for a low operational cost and reliable measurements to provide daily aerosol monitoring. The exposure of diethylene-glycol bis (allylcarbonate) to radiation causes modification of its physico-chemical properties like surface roughness and reflectance. In the present study, optical sensor based on the reflectance measurement has been developed with an aim to monitor real time presence of alpha radioactive aerosols emitted from thorium nitrate hydrate. The results shows that the fabricated sensor can detect 0.0157 kBq to 0.1572 kBq of radio activity by radioactive aerosols generated from (Th(NO{sub 3}){sub 4} ⋅ 5H{sub 2}O) at 0.1 ml/min flow rate. The proposed instrument will be helpful to monitor radioactive aerosols in/around a nuclear facility, building construction sites, mines, and granite polishing factories.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Incorporating radioactive decay into charging and coagulation of multicomponent radioactive aerosols

Compositional changes by the decay of radionuclides in radioactive aerosols can influence their charging state, coagulation frequency and size distribution throughout their atmospheric lifetime. The importance of such effects is unknown as they have not been considered in microphysical and global radioactivity transport studies to date. Here, we explore the effects of compositional changes on the charging efficiency and coagulation rates of aerosols using a set of kinetic equations that couple all relevant processes (decay, charging and coagulation) and their evolution over time. Compared to a coupled aggregation-tracer model for the prediction of the radioactive composition of particulates undergoing coagulation, our kinetic approach can provide similar results using much less central processing unit time. Altogether with other considerations, our approach is computational efficient enough to allow implementation in 3D atmospheric transport models. The decay of radionuclides and the production of decay products within radioactive aerosols may significantly affect the aerosol charging rates, and either hinder or promote the coagulation of multicomponent radioactive aerosols. Our results suggest that radiological phenomena occurring within radioactive aerosols, as well as subsequent effects on aerosol microphysics, should be considered in regional and global models to more accurately predict radioactivity transport in the atmosphere in case of a nuclear plant accident.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Evaluation of Radioactive Aerosol Precipitation on the Inner Surfaces of Steam-Water Lines in Beyond Design Basis Accidents at NPP with RBMK

The results of modeling performed with the MELCOR code of the transport and precipitation of fission product aerosols in the steam-water lines of RBMK during beyond design basis accidents are presented. It is shown that the precipitation of fission product aerosols on the inner surfaces of steam-water lines depends on the course of the accident and can be an effective mechanism for lowering their atmospheric emissions.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2020

Estimating a protection factor from homemade facemasks for Los Alamos radioactive aerosols

The Los Alamos National Laboratory has required usage of facemasks “whenever interacting with or near others." The present document estimates the respiratory protection factor of homemade facemasks to be 1.4 and 1.2 for aerosol particles, below and above 0.3 μm diameter, respectively. This includes an estimated leakage of 70% and 52% for aerosol particles below and above 0.3 μm diameter, respectively.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2024

Assessing the release, transport, and retention of radioactive aerosols from hypothetical breaches in spent fuel storage canisters

Interim dry storage of spent nuclear fuel involves storing the fuel in welded stainless-steel canisters. Under certain conditions, the canisters could be subjected to environments that may promote stress corrosion cracking leading to a risk of breach and release of aerosol-sized particulate from the interior of the canister to the external environment through the crack. Research is currently under way by several laboratories to better understand the formation and propagation of stress corrosion cracks, however little work has been done to quantitatively assess the potential aerosol release. The purpose of the present work is to introduce a reliable generic numerical model for prediction of aerosol transport, deposition, and plugging in leak paths similar to stress corrosion cracks, while accounting for potential plugging from particle deposition. The model is dynamic (changing leak path geometry due to plugging) and it relies on the numerical solution of the aerosol transport equation in one dimension using finite differences. The model’s capabilities were also incorporated into a Graphical User Interface (GUI) that was developed to enhance user accessibility. Model validation efforts presented in this paper compare the model’s predictions with recent experimental data from Sandia National Laboratories (SNL) and results available in literature. We expect this model to improve the accuracy of consequence assessments and reduce the uncertainty of radiological consequence estimations in the remote event of a through-wall breach in dry cask storage systems.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Computational multiphysics modeling of radioactive aerosol deposition in diverse human respiratory tract geometries

The evaluation of aerosol exposure relies on generic mathematical models that assume uniform particle deposition profiles over the human respiratory tract and do not account for subject-specific characteristics. Here we introduce a hybrid-automated computational workflow that generates personalized particle deposition profiles in 3D reconstructed human airways from computed tomography scans using Computational Fluid and Particle Dynamics simulations. This is the first large-scale study to consider realistic airways variability, where 380 lower and 40 upper human respiratory tract 3D geometries are reconstructed and parameterized. The data is clustered into nine groups using random forest regression. Computational fluid and particle dynamics simulations are conducted on these representative geometries using a realistic heavy-breathing respiratory cycle and radioactive iodine-131 as a source term. Monte Carlo radiation transport simulations are performed to obtain detailed energy deposition maps. Our findings emphasize the importance of personalized studies, as minor respiratory tract variations notably influence deposition patterns rather than global parameters of the lower airways, observing more than 30% variance in the mass deposition fraction.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2025

Experimental and Computational Characterization of a Modified Sioutas Cascade Impactor for Respirable Radioactive Aerosols

Oak Ridge National Laboratory is collecting and characterizing aerosols released when spent nuclear fuel (SNF) rods are fractured in bending. An aerosol collection system was designed and tested to collect respirable sized (<10 μm aerodynamic diameter [AED]) particulates inside a hot cell facility. The setup is a modified version of the commercially available Sioutas cascade impactor, to which additional stages were added to expand the aerosol collection range from 2.5 to ~15 μm AED. To accommodate the additional stages and specific test conditions, the operating flow rate for aerosol collection was reduced, and testing was conducted by using pressure drop measurements, surrogate dust collection, and particle size characterization. The fluid flow distribution within the cascade and its stages was simulated in STAR-CCM+, and the stage-wise pressure drops obtained using the computational fluid dynamics model were then compared to experimental data. Lagrangian particle simulations were also performed, and stage-wise collection statistics were obtained from the simulation for comparison with the experimental data obtained using SNF-surrogate dust particles. The results provide valuable insights into the stage-wise particle collection characteristics of the modified cascade impactor and can also be used to improve the prediction accuracy of the manufacturer-determined analytical correlations.

aerosol modeling↗
DOE OSTI2015

Equipment for the continuous measurement and identification of gamma radioactivity on aerosols

Presentation the Equipment for the Continuous Measurement and Identification of Gamma Radioactivity on Aerosols developed by the Nuclear Engineering Research Group (NERG) from the Technical University of Catalonia (UPC) and the Raditel Company. The device is based on a fixed filter of glass fiber (100% borosilicate), this allows determine the concentration of activity of gamma emitters on aerosols in air. A specifically developed Spectrometry Analysis System has been developed. The analysis of the spectra allows the identification of the emitters and determine the concentration of activity. Nowadays four Stations with this equipment are operating on the Environmental Radiological Surveillance Network of the Catalonian Generalitat (Spain): two near the Asco and Vandellos Nuclear Power Plants in the province of Tarragona and one in the city of Barcelona. Soon a fourth monitor will be incorporated at Roses (province of Girona) and a fifth in Puigcerda (province of Barcelona). We present measurements and analysis of the evolution of the emitters identified on different stations of the Network. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2013

Prediction of radiation doses during the dismantling of the pressurized tank from emergency core cooling system of RBMK- 1500 reactor

Preparation for the decommissioning of the Ignalina Nuclear Power Plant involves multiple problems. Personnel radiation safety during the performance of dismantling activities is one of them. In order to assess the optimal personnel radiation safety, the modelling is performed for large components by the means of computer code 'VISIPLAN 3D ALARA Planning tool' developed by SCK CEN (Belgium). Modelling results of radiation doses during the dismantling of the pressurized tank from the emergency core cooling system (ECCS PT) of RBMK-1500 reactor are presented in this paper. The mass of one ECCS PT is approximately 47.6 tons. The radiological surveys indicate that the inner surface of the ECCS PT is contaminated with radioactive products of corrosion and sediments due to the radioactive water. The assessment of workers exposure was performed to comply with ALARA. The effective doses to the workers were modeled for different strategies of ECCS PT dismantling. The impact of dismantling tools and shielding types and extract ventilation flow rate during the dismantling of ECCS PT on effective doses were analyzed. The total effective personnel doses were obtained by summarizing the effective personnel doses from various sources of exposure, i. e., direct radiation from radioactive equipment, internal radiation due to inhalation of radioactive aerosols, and direct radiation from radioactive aerosols arising during hot cutting in premises. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Nuclear Emergency and the Atmospheric Dispersion of Nuclear Aerosols: Discussion of the Shared Nuclear Future - 13163

This paper has a twofold objective. One is to analyze the current status of high-level nuclear waste disposal along with presentation of practical perspectives about the environmental issues involved. Present disposal designs and concepts are analyzed on a scientific basis and modifications to existing designs are proposed from the perspective of environmental safety. Other is to understand the aerosol formation in the atmosphere for the case of the leakage from the nuclear waste containers or a nuclear accident. Radio-nuclides released from the waste will attach themselves to the existing aerosols in the atmosphere along with formation of new aerosols. Anticipating the nuclear accident when a variety of radioactive aerosols will form and exist in the atmosphere, as a simple example, measurement of naturally existing radioactive aerosols are made in the atmosphere of Islamabad and Murree. A comparison with similar measurements in 3 cities of France is provided. Measurement of radionuclides in the atmosphere, their attachment to aerosols and follow up transport mechanisms are key issues in the nuclear safety. It is studied here how {sup 7}Be concentration in the atmospheric air varies in the capital city of Islamabad and a Himalaya foothill city of Murree (Pakistan). Present results are compared with recent related published results to produce a {sup 7}Be concentration versus altitude plot up to an altitude of 4000 m (a.s.l.). Origin and variance of {sup 7}Be concentration at different altitudes is discussed in detail. The relevance of results presented here with the evaluation of implications of Chernobyl and Fukushima nuclear disasters has been discussed in a conclusive manner. It is the first international report of a joint collaboration/project. The project is being generalized to investigate and formulate a smooth waste storage and disposal policy. The project will address the fission and fusion waste reduction, its storage, its recycling, air, water and soil quality monitoring, and the final disposal with the major foci of dealing with related chemical, biogical, physical, geophysical, engineering, management and administration aspects. (authors)

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

A new code for spectrometric analysis for environmental radiological surveillance on monitors focused on gamma radioactivity on aerosols

pGamma is a code developed by the NERG group of the Technical University of Catalonia - Barcelona Tech for the analysis of gamma spectra generated by the Equipment for the Continuous Measurement and Identification of Gamma Radioactivity on Aerosols with Paper Filter developed for our group and Raditel Servies company. Nowadays the code is in the process of adaptation for the monitors of the Environmental Radiological Surveillance Network of the Local Government of Catalonia (Generalitat of Catalonia), Spain. The code is a Spectrum Analysis System, it identifies the gamma emitters on the spectrum, determines its Concentration of Activity, generates alarms depending on the Activity of the emitters and generates a report. The Spectrum Analysis System includes a library with emitters of interest, NORM and artificial. The code is being used on the three stations with the aerosol monitor of the Network (Asco and Vandellos, near both Nuclear Power Plants and Barcelona). (authors)

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Aerosol Measurement from Plasma Arc Torch Cuts on Various Metal for D and D Workers' Internal Dose Calculation - 20253

When dismantling a nuclear power plant, structures must be cut to reduce size. The cutting of radioactive material produces radioactive aerosols, which pose a health risk including radiation risk to site workers and the general public. However, due to a lack of research on the physical and chemical characteristics of aerosols produced in these processes, the calculation of internal dose in the event of an expected or unexpected accident is inaccurate. For the measurement of aerosols generated from cutting for internal dose calculations, we measured the number concentration distribution and nuclide distribution of aerosols from plasma arc cutting in a laboratory experimental setup, considering isokinetic sampling and automatic cutting. The results may suggest internal dose assessment without characteristics of radioactive aerosol has uncertainty and the possibility of being undervalued. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Dismantling Structures and Equipment of the MR Reactor and its Loop Facilities at the National Research Center 'Kurchatov Institute' - 12051

In 2008 a design of decommissioning of research reactors MR and RFT has been developed in the National research Center 'Kurchatov institute'. The design has been approved by Russian State Authority in July 2009 year and has received the positive conclusion of ecological expertise. In 2009-2010 a preparation for decommissioning of reactors MR and RFT was spent. Within the frames of a preparation a characterization, sorting and removal of radioactive objects, including the irradiated fuel, from reactor storage facilities and pool have been executed. During carrying out of a preparation on removal of radioactive objects from reactor sluice pool water treating has been spent. For these purposes modular installation for clearing and processing of a liquid radioactive waste 'Aqua - Express' was used. As a result of works it was possible to lower volume activity of water on three orders in magnitude that has allowed improving essentially of radiating conditions in a reactor hall. Auxiliary systems of ventilation, energy and heat supplies, monitoring systems of radiating conditions of premises of the reactor and its loop-back installations are reconstructed. In 2011 the license for a decommissioning of the specified reactors has been received and there are begun dismantling works. Within the frames of works under the design the armature and pipelines are dismantled in a under floor space of a reactor hall where a moving and taking away pipelines of loop facilities and the first contour of the MR reactor were replaced. A dismantle of the main equipment of loop facility with the gas coolant has been spent. Technologies which were used on dismantle of the radioactive contaminated equipment are presented, the basic works on reconstruction of systems of maintenance of on the decommissioning works are described, the sequence of works on the decommissioning of reactors MR and RFT is shown. Dismantling works were carried out with application of means of a dust suppression that, in aggregate with standard means at such works of individual protection of the personnel and devices of radiating control, has allowed to lower risk of action of radiation on the personnel, the population and environment at the expense of reduction of volume activity of radioactive aerosols in air. (authors)

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

Radiological Consequences of Hydrogen Explosions in Vessels and Piping at the WTP

Hydrogen (along with other gases) is generated in process vessels and other components at the Hanford Waste Treatment and Immobilization Plant (WTP) due to the radiolysis of water and to the radiolysis and thermolysis of organics in WTP radioactive process wastes. In the absence of controls, the hydrogen may accumulate until a flammable or explosive concentration is reached. Once a buildup has occurred, ignition of the hydrogen causes an explosion that creates radioactive aerosols that could escape the confinement boundary and be released to the environment. Such a release could cause significant radiological exposures to a public receptor at the site boundary and to a co-located worker (CLW/) in the yard areas outside the physical facilities. Hydrogen explosion events therefore require evaluation as to the potential magnitude of their consequences. The WTP methodology for the evaluation of the potential radiological consequences due to hydrogen explosions in vessels and piping is a conservative approach that is defensible from a regulatory standpoint yet only results in the need for Safety controls for the most highly radioactive process vessels (generally those containing waste with significant quantities of solids). For WTP vessels with waste not containing significant quantities of solids, radiological dose consequences are sufficiently low such that neither Safety Class controls for the public receptor nor Safety Significant controls for the CLW are required. Similarly, the dose consequences for hydrogen explosions in piping and ancillary vessels are all very low to both receptors, again indicating that no Safety Class or Safety Significant controls are required. The WTP vessel and piping hydrogen explosion calculations are dependent on vessel and pipe sizes, hydrogen generation rates, operational requirements, and waste stream properties such as solids content, radioisotope concentration, and slurry density. Consequently, the WTP-specific results discussed above cannot be extrapolated directly to other facilities. (authors)

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

Thermal Testing of Waste Packages for a Storage Environment

The Pipe Overpack Container (POC) was developed at Rocky Flats to transport plutonium residues with higher levels of plutonium than standard TRU waste to the Waste Isolation Pilot Plant (WIPP) for disposal. The POC consists of an inner Pipe Container (PC) surrounded by organic fiber dunnage inside of a 7A drum. The PC was design to maintain separation of fissile material and to provide shielding from radiation. The POC has many design features that are similar to Type B packages that do provide protection from engulfing fires. However, it was not specifically designed to prevent release of stored material during a long-duration fire. POCs are now being used to store combustible TRU waste at Department of Energy (DOE) sites (e.g., Waste Isolation Pilot Plant). Radioactive waste storage operators would like to be able to claim some level of protection is provided by the POCs for thermal assaults that could occur within storage facilities when these POCs contain PCs with combustibles. In 1997 Sandia National Laboratories (SNL) conducted a series of tests to determine the degree of protection POCs provide during storage accident events. One of these tests exposed four of the POCs to a 30-minute engulfing pool fire, resulting in one of the 7A drums generating sufficient internal pressure to pop off its lid and expose the top of the PC to the fire environment. However, these tests are not bounding for POC/PC containing combustibles. With the addition of combustible materials in the PC, the possibility exists for generation of higher quantities of gases and much higher pressures inside the PC, which can lead to early rupture of the PC filter and higher radioactive aerosol release fractions. Therefore, a new series of tests was required to determine the temperature response of the exposed PC and determine the amount of material that could be released. DOE contacted SNL in 2015 to discuss the 1997 SNL tests and came to the conclusion that those tests were not bounding for POC/PC containing combustibles Therefore, DOE commission a new set of tests at SNL. Starting in 2015, SNL conducted fire tests to examine whether the contents of the PC would reach a temperature that would result in generation of sufficient gas to cause overpressurization of the PC, and subsequent release of its content. This paper will describe the various test conducted thus far, and present preliminary results from these tests.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

Performance assessment on continuous air monitors under real operating conditions

In the nuclear industry, workers may be exposed to artificial radioactive aerosols. These aerosols are generally composed of particles with a diameter measuring between 0.1 {mu}m and 10 {mu}m. To protect workers in nuclear facilities, monitors that continuously measure radioactivity in the air are used. The main function of the monitor is to provide real-time measurement of activity concentration. Measurement of aerosol activity concentration can be affected by a number of factors specific to the aerosols and the instrument. The first part of the article will present the general operating principles of continuous air monitors (CAMs) and inherent measurement difficulties, as well as the main standard tests. The second section describes the experimental ICARE facility The ICARE facility generates standard artificial and natural radioactive aerosols for calibrating continuous air monitors under real operating conditions. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗