504 Matching Results

Search Results

Advanced search parameters have been applied.

Unabated emission source term estimate for the 340-NX stack

Description: This document contains the sampling procedure, analytical results, and source term estimate from sampling work conducted on the main stack for the 340 Facility`s vault ventilation system. Several air filter and carbon cartridges were collected upstream of the KI off-gas control modules in order to determine the challenge source terms associated with various operating modes (e.g., under routine waste storage, during waste mixing, during waste transfer, etc.)
Date: March 19, 1997
Creator: Stordeur, R.T. & Glissmeyer, J.A., Fluor Daniel Hanford
Partner: UNT Libraries Government Documents Department

Machine-inudced backgrounds: their origin and loads on ATLAS/CMS

Description: A detailed analysis of machine-induced backgrounds (MIB) in the LHC collider detectors is performed with focus on origin and rates for three sources: tertiary beam halo, beam-gas interactions and kicker prefire. Particle fluxes originating from these operational and accidental beam losses are carefully calculated with the MARS15 code and presented at the entrance to the ATLAS and CMS experimental halls. It is shown that background rates in detector subsystems strongly depend on the origin of MIB, particle energy and type. Using this source term, instantaneous and integrated loads on the detectors and impact on the detector performance can be derived.
Date: May 1, 2008
Creator: Mokhov, N.V.; /Fermilab; Weiler, T. & /CERN
Partner: UNT Libraries Government Documents Department

A weighted adjoint-source for weight-window generation by means of a linear tally combination

Description: A new importance estimation technique has been developed that allows weight-window optimization for a linear combination of tallies. This technique has been implemented in a local version of MCNP and effectively weights the adjoint source term for each tally in the combination. Optimizing weight window parameters for the linear tally combination allows the user to optimize weight windows for multiple regions at once. In this work, we present our results of solutions to an analytic three-tally-region test problem and a flux calculation on a 100,000 voxel oil-well logging tool problem.
Date: January 1, 2009
Creator: Sood, Avneet; Booth, Thomas E & Solomon, Clell J
Partner: UNT Libraries Government Documents Department

A perturbation expansion approach to solving the electromagnetic induction problem in three dimensions.

Description: We address the electromagnetic induction problem for fully 3D geologic media and present a solution to the governing Maxwell equations based on a power series expansion. The coefficients in the series are computed using the adjoint method assuming an underlying homogeneous reference model. These solutions are available analytically for point dipole source terms and lead to rapid calculation of the expansion coefficients. First order solutions are presented for a model study in petroleum geophysics composed of a multi-component induction sonde proximal to a fault within a compartmentalized hydrocarbon reservoir.
Date: October 1, 2003
Creator: Tobin, Harold (New Mexico Tech, Socorro, NM); Natek, Nancy H. & Weiss, Chester Joseph
Partner: UNT Libraries Government Documents Department

Dynamic Data-Driven Event Reconstruction for Atmospheric Releases

Description: Accidental or terrorist releases of hazardous materials into the atmosphere can impact large populations and cause significant loss of life or property damage. Plume predictions have been shown to be extremely valuable in guiding an effective and timely response. The two greatest sources of uncertainty in the prediction of the consequences of hazardous atmospheric releases result from poorly characterized source terms and lack of knowledge about the state of the atmosphere as reflected in the available meteorological data. In this report, we discuss the development of a new event reconstruction methodology that provides probabilistic source term estimates from field measurement data for both accidental and clandestine releases. Accurate plume dispersion prediction requires the following questions to be answered: What was released? When was it released? How much material was released? Where was it released? We have developed a dynamic data-driven event reconstruction capability which couples data and predictive models through Bayesian inference to obtain a solution to this inverse problem. The solution consists of a probability distribution of unknown source term parameters. For consequence assessment, we then use this probability distribution to construct a ''''composite'' forward plume prediction which accounts for the uncertainties in the source term. Since in most cases of practical significance it is impossible to find a closed form solution, Bayesian inference is accomplished by utilizing stochastic sampling methods. This approach takes into consideration both measurement and forward model errors and thus incorporates all the sources of uncertainty in the solution to the inverse problem. Stochastic sampling methods have the additional advantage of being suitable for problems characterized by a non-Gaussian distribution of source term parameters and for cases in which the underlying dynamical system is non-linear. We initially developed a Markov Chain Monte Carlo (MCMC) stochastic methodology and demonstrated its effectiveness by reconstructing a wide range ...
Date: February 22, 2007
Creator: Kosovic, B; Belles, R; Chow, F K; Monache, L D; Dyer, K; Glascoe, L et al.
Partner: UNT Libraries Government Documents Department

Event Reconstruction for Atmospheric Releases Employing Urban Puff Model UDM with Stochastic Inversion Methodology

Description: The rapid identification of contaminant plume sources and their characteristics in urban environments can greatly enhance emergency response efforts. Source identification based on downwind concentration measurements is complicated by the presence of building obstacles that can cause flow diversion and entrainment. While high-resolution computational fluid dynamics (CFD) simulations are available for predicting plume evolution in complex urban geometries, such simulations require large computational effort. We make use of an urban puff model, the Defence Science Technology Laboratory's (Dstl) Urban Dispersion Model (UDM), which employs empirically based puff splitting techniques. UDM enables rapid urban dispersion simulations by combining traditional Gaussian puff modeling with empirically deduced mixing and entrainment approximations. Here we demonstrate the preliminary reconstruction of an atmospheric release event using stochastic sampling algorithms and Bayesian inference together with the rapid UDM urban puff model based on point measurements of concentration. We consider source inversions for both a prototype isolated building and for observations and flow conditions taken during the Joint URBAN 2003 field campaign at Oklahoma City. The Markov Chain Monte Carlo (MCMC) stochastic sampling method is used to determine likely source term parameters and considers both measurement and forward model errors. It should be noted that the stochastic methodology is general and can be used for time-varying release rates and flow conditions as well as nonlinear dispersion problems. The results of inversion indicate the probability of a source being at a particular location with a particular release rate. Uncertainty in observed data, or lack of sufficient data, is inherently reflected in the shape and size of the probability distribution of source term parameters. Although developed and used independently, source inversion with both UDM and a finite-element CFD code can be complementary in determining proper emergency response to an urban release. Ideally, the urban puff model is used to approximate ...
Date: November 3, 2005
Creator: Neuman, S; Glascoe, L; Kosovic, B; Dyer, K; Hanley, W; Nitao, J et al.
Partner: UNT Libraries Government Documents Department

Dynamic Data-Driven Event Reconstruction for Atmospheric Releases

Description: The role of an event reconstruction capability in a case of an atmospheric release is to characterize the source by answering the critical questions--How much material was released? When? Where? and What are the potential consequences? Accurate estimation of the source term is essential to accurately predict plume dispersion, effectively manage the emergency response, and mitigate consequences in a case of an atmospheric release of hazardous material. We are developing a capability that seamlessly integrates observational data streams with predictive models in order to provide probabilistic estimates of unknown source term parameters consistent with both data and model predictions. Our approach utilizes Bayesian inference with stochastic sampling using Markov Chain and Sequential Monte Carlo methodology. The inverse dispersion problem is reformulated into a solution based on efficient sampling of an ensemble of predictive simulations, guided by statistical comparisons with data. We are developing a flexible and adaptable data-driven event-reconstruction capability for atmospheric releases that provides (1) quantitative probabilistic estimates of the principal source-term parameters (e.g., the time-varying release rate and location); (2) predictions of increasing fidelity as an event progresses and additional data become available; and (3) analysis tools for sensor network design and uncertainty studies. Our computational framework incorporates multiple stochastic algorithms, operates with a range and variety of atmospheric models, and runs on multiple computer platforms, from workstations to large-scale computing resources. Our final goal is a multi-resolution capability for both real-time operational response and high fidelity multi-scale applications.
Date: April 19, 2006
Creator: Mirin, A A & Kosovic, B
Partner: UNT Libraries Government Documents Department

Technical Review of SRS Dose Reconstrruction Methods Used By CDC

Description: At the request of the Centers for Disease Control and Prevention (CDC), a subcontractor Advanced Technologies and Laboratories International, Inc.(ATL) issued a draft report estimating offsite dose as a result of Savannah River Site operations for the period 1954-1992 in support of Phase III of the SRS Dose Reconstruction Project. The doses reported by ATL differed than those previously estimated by Savannah River Site SRS dose modelers for a variety of reasons, but primarily because (1) ATL used different source terms, (2) ATL considered trespasser/poacher scenarios and (3) ATL did not consistently use site-specific parameters or correct usage parameters. The receptors with the highest dose from atmospheric and liquid pathways were within about a factor of four greater than dose values previously reported by SRS. A complete set of technical comments have also been included.
Date: July 20, 2005
Creator: Simpkins, Ali, A
Partner: UNT Libraries Government Documents Department

ACCUMULATION OF RADIOCESIUM BY MUSHROOMS IN THE ENVIRONMENT: A LITERATURE REVIEW AND IMAGE GALLERY

Description: During the last 50 years, a large amount of information on radionuclide accumulators or 'sentinel-type' organisms in the environment has been published. Much of this work focused on the risks of food-chain transfer of radionuclides to higher organisms such as reindeer and man. However, until the 1980's and 1990's, there has been little published data on the radiocesium ({sup 134}Cs and {sup 137}Cs) accumulation by mushrooms. This presentation will consist of a review of the published data for {sup 134,137}Cs accumulation by mushrooms in nature. The review will consider the time of sampling, sample location characteristics, the radiocesium source term and other aspects that promote {sup 134,137}Cs uptake by mushrooms. This review will focus on published data for mushrooms that demonstrate a large propensity for use in the environmental biomonitoring of radiocesium contamination. It will also provide photographs and descriptions of habitats for many of these mushrooms to facilitate their collection for biomonitoring.
Date: November 5, 2006
Creator: Duff, M & Mary Ramsey, M
Partner: UNT Libraries Government Documents Department

The development of a realistic source term for sodium-cooled fast reactors : assessment of current status and future needs.

Description: Sodium-cooled fast reactors (SFRs) continue to be proposed and designed throughout the United States and the world. Although the number of SFRs actually operating has declined substantially since the 1980s, a significant interest in advancing these types of reactor systems remains. Of the many issues associated with the development and deployment of SFRs, one of high regulatory importance is the source term to be used in the siting of the reactor. A substantial amount of modeling and experimental work has been performed over the past four decades on accident analysis, sodium coolant behavior, and radionuclide release for SFRs. The objective of this report is to aid in determining the gaps and issues related to the development of a realistic, mechanistically derived source term for SFRs. This report will allow the reader to become familiar with the severe accident source term concept and gain a broad understanding of the current status of the models and experimental work. Further, this report will allow insight into future work, in terms of both model development and experimental validation, which is necessary in order to develop a realistic source term for SFRs.
Date: June 1, 2011
Creator: LaChance, Jeffrey L.; Phillips, Jesse; Parma, Edward J., Jr.; Olivier, Tara Jean & Middleton, Bobby D.
Partner: UNT Libraries Government Documents Department

A General Method to Estimate Earthquake Moment and Magnitude using Regional Phase Amplitudes

Description: This paper presents a general method of estimating earthquake magnitude using regional phase amplitudes, called regional M{sub o} or regional M{sub w}. Conceptually, this method uses an earthquake source model along with an attenuation model and geometrical spreading which accounts for the propagation to utilize regional phase amplitudes of any phase and frequency. Amplitudes are corrected to yield a source term from which one can estimate the seismic moment. Moment magnitudes can then be reliably determined with sets of observed phase amplitudes rather than predetermined ones, and afterwards averaged to robustly determine this parameter. We first examine in detail several events to demonstrate the methodology. We then look at various ensembles of phases and frequencies, and compare results to existing regional methods. We find regional M{sub o} to be a stable estimator of earthquake size that has several advantages over other methods. Because of its versatility, it is applicable to many more events, particularly smaller events. We make moment estimates for earthquakes ranging from magnitude 2 to as large as 7. Even with diverse input amplitude sources, we find magnitude estimates to be more robust than typical magnitudes and existing regional methods and might be tuned further to improve upon them. The method yields a more meaningful quantity of seismic moment, which can be recast as M{sub w}. Lastly, it is applied here to the Middle East region using an existing calibration model, but it would be easy to transport to any region with suitable attenuation calibration.
Date: November 19, 2009
Creator: Pasyanos, M E
Partner: UNT Libraries Government Documents Department

Stable grid refinement and singular source discretization for seismic wave simulations

Description: An energy conserving discretization of the elastic wave equation in second order formulation is developed for a composite grid, consisting of a set of structured rectangular component grids with hanging nodes on the grid refinement interface. Previously developed summation-by-parts properties are generalized to devise a stable second order accurate coupling of the solution across mesh refinement interfaces. The discretization of singular source terms of point force and point moment tensor type are also studied. Based on enforcing discrete moment conditions that mimic properties of the Dirac distribution and its gradient, previous single grid formulas are generalized to work in the vicinity of grid refinement interfaces. These source discretization formulas are shown to give second order accuracy in the solution, with the error being essentially independent of the distance between the source and the grid refinement boundary. Several numerical examples are given to illustrate the properties of the proposed method.
Date: October 30, 2009
Creator: Petersson, N A & Sjogreen, B
Partner: UNT Libraries Government Documents Department

Preliminary tank characterization report for single-shell tank 241-SX-105: Best-basis inventory

Description: An effort is underway to provide waste inventory estimates that will serve as standard characterization source terms for the various waste management activities. As part of this effort, an evaluation of available information for single-shell tank 241-SX-105 was performed, and a best-basis inventory was established. This work follows the methodology that was established by the standard inventory task.
Date: August 29, 1997
Creator: Kupfer, M.J.
Partner: UNT Libraries Government Documents Department

Preliminary tank characterization report for single-shell tank 241-SX-111: Best-basis inventory

Description: An effort is underway to provide waste inventory estimates that will serve as standard characterization source terms for the various waste management activities. As part of this effort,.an evaluation of available information for single-shell tank 241-SX-111 was performed, and a best-basis inventory was established. This work follows the methodology that was established by the standard inventory task.
Date: August 29, 1997
Creator: Kupfer, M.J.
Partner: UNT Libraries Government Documents Department

Preliminary tank characterization report for single-shell tank 241-SX-107: Best-basis inventory

Description: An effort is underway to provide waste inventory estimates that will serve as standard characterization source terms for the various waste management activities. As part of this effort, an evaluation of available information for single-shell tank 241-SX-107 was performed, and a best-basis inventory was established. This work follows the methodology that was established by the standard inventory task.
Date: August 29, 1997
Creator: Kupfer, M.J.
Partner: UNT Libraries Government Documents Department

Preliminary tank characterization report for single-shell tank 241-SX-106: Best-basis inventory

Description: An effort is underway to provide waste inventory estimates that will serve as standard characterization source terms for the various waste management activities. As part of this effort, an evaluation of available information for single-shell tank 241-SX-106 was performed, and a best-basis inventory was established. This work follows the methodology that was established by the standard inventory task.
Date: August 29, 1997
Creator: Kupfer, M.J.
Partner: UNT Libraries Government Documents Department

From Molecular Dynamics to Kinetic Rate Theory: A Simple Example of Multiscale Modeling

Description: Radiation damage formation in iron has been investigated using the method of molecular dynamics simulation. The MD simulations have been used to determine primary defect production parameters for cascade energies up to 50 keV at temperatures from 100 to 900K. The energy dependence of these parameters has been used to determine appropriate neutron-energy-spectrum averaged damage production cross sections for various irradiation environments. Two applications of these effective cross sections are discussed. The first is an evaluation of neutron energy spectrum effects in commercial fission reactor pressure vessels. The second example deals with the use of these cross sections in the source term of a kinetic model used to predict void swelling and microstructural evolution. The simulation of the primary damage event by MD involves times less than 100 ps and a size scale of a few tens of nm, while the kinetic simulation encompasses several years and macroscopic sizes. This use of the MD results to develop an improved source term for rate theory modeling provides a simple example of multiscale modeling.
Date: November 30, 1998
Creator: Greenwood, L.R. & Stoller, R.E.
Partner: UNT Libraries Government Documents Department

Preliminary tank characterization report for single-shell tank 241-TX-103: Best-basis inventory

Description: An effort is underway to provide waste inventory estimates that will serve as standard characterization source terms for the various waste management activities. As part of this effort, an evaluation of available information for single-shell tank 241-TX-103 was performed, and a best-basis inventory was established. This work follows the methodology that was established by the standard inventory task. The best-basis inventory is based on an engineering assessment of waste type, process flowsheet data, early sample data, and/or other available information. The Standard Inventories of Chemicals and Radionuclides in Hanford Site Tank Wastes (Kupfer et al. 1997) describes standard methodology used to derive the tank-by-tank best-basis inventories. This preliminary TCR will be updated using this same methodology when additional data on tank contents become available.
Date: August 26, 1997
Creator: Hendrickson, D.W.
Partner: UNT Libraries Government Documents Department

Preliminary tank characterization report for single-shell tank 241-TX-110: Best-basis inventory

Description: An effort is underway to provide waste inventory estimates that will serve as standard characterization source terms for the various waste management activities. As part of this effort, an evaluation of available information for single-shell tank 241-TX-110 was performed, and a best-basis inventory was established. This work follows the methodology that was established by the standard inventory task.
Date: August 26, 1997
Creator: Place, D.E.
Partner: UNT Libraries Government Documents Department

Preliminary tank characterization report for single-shell tank 241-TX-112: Best-basis inventory

Description: An effort is underway to provide waste inventory estimates that will serve as standard characterization source terms for the various waste management activities. As part of this effort, an evaluation of available information for single-shell tank 241-TX-112 was performed, and a best-basis inventory was established. This work follows the methodology that was established by the standard inventory task. The best-basis inventory is based on an engineering assessment of waste type, process flowsheet data, early sample data, and other available information. The Standard Inventories of Chemicals and Radionuclides in Hanford Site Tank Wastes (Kupfer et al. 1997) describes standard methodology used to derive the tank-by-tank best-basis inventories. This preliminary TCR will be updated using this same methodology when additional data on tank contents become available.
Date: August 26, 1997
Creator: Place, D.E.
Partner: UNT Libraries Government Documents Department

Preliminary tank characterization report for single-shell tank 241-TX-111: Best-basis inventory

Description: An effort is underway to provide waste inventory estimates that will serve as standard characterization source terms for the various waste management activities. As part of this effort, an evaluation of available information for single-shell tank 241-TX-111 was performed, and a best-basis inventory was established. This work follows the methodology that was established by the standard inventory task. The best-basis inventory is based on an engineering assessment of waste type, process flowsheet data, early sample data, and/or other available information. The Standard Inventories of Chemicals and Radionuclides in Hanford Site Tank Wastes (Kupfer et al. 1997) describes standard methodology used to derive the tank-by-tank best-basis inventories. This preliminary TCR will be updated using this same methodology when additional data on tank contents become available.
Date: August 26, 1997
Creator: Place, D.E.
Partner: UNT Libraries Government Documents Department

Preliminary tank characterization report for single-shell tank 241-SX-112: Best-basis inventory

Description: An effort is underway to provide waste inventory estimates that will serve as standard characterization source terms for the various waste management activities. As part of this effort, an evaluation of available information for single-shell tank 241-SX-112 was performed, and a best-basis, inventory was established. This work follows the methodology that was established by the standard inventory task.
Date: August 29, 1997
Creator: Kupfer, M.J.
Partner: UNT Libraries Government Documents Department

Verification of VENTSAR XL - a spreadsheet version of VENTSAR

Description: VENTSAR is a computer model that analyzes flow patterns of pollutants on or near buildings. Plume rise may be considered. VENTSAR has been modified to allow for execution on a Macintosh using Microsoft Excel. This new version is called VENTSAR XL. All methodologies are identical to those within VENTSAR. This report provides verification of all models within VENTSAR XL. Strict comparisons were made with VENTSAR to ensure consistency between the two models
Date: May 1, 1996
Creator: Simpkins, A.A.
Partner: UNT Libraries Government Documents Department

Preliminary tank characterization report for single-shell tank 241-TX-106: Best-basis inventory

Description: An effort is underway to provide waste inventory estimates that will serve as standard characterization source terms for the various waste management activities. As part of this effort, an evaluation of available information for single-shell tank 241-TX-106 was performed, and a best-basis inventory was established. This work follows the methodology that was established by the standard inventory task. The best-basis inventory is based on an engineering assessment of waste type, process flowsheet data, early sample data, and/or other available information. The Standard Inventories of Chemicals and Radionuclides in Hanford Site Tank Wastes (Kupfer et al. 1997) describes standard methodology used to derive the tank-by-tank best-basis inventories. This preliminary TCR will be updated using this same methodology when additional data on tank contents become available.
Date: August 26, 1997
Creator: Kupfer, M.J.
Partner: UNT Libraries Government Documents Department