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Development of Parallel Computing Framework to Enhance Radiation Transport Code Capabilities for Rare Isotope Beam Facility Design

Description: A parallel computing framework has been developed to use with general-purpose radiation transport codes. The framework was implemented as a C++ module that uses MPI for message passing. It is intended to be used with older radiation transport codes implemented in Fortran77, Fortran 90 or C. The module is significantly independent of radiation transport codes it can be used with, and is connected to the codes by means of a number of interface functions. The framework was developed and tested in conjunction with the MARS15 code. It is possible to use it with other codes such as PHITS, FLUKA and MCNP after certain adjustments. Besides the parallel computing functionality, the framework offers a checkpoint facility that allows restarting calculations with a saved checkpoint file. The checkpoint facility can be used in single process calculations as well as in the parallel regime. The framework corrects some of the known problems with the scheduling and load balancing found in the original implementations of the parallel computing functionality in MARS15 and PHITS. The framework can be used efficiently on homogeneous systems and networks of workstations, where the interference from the other users is possible.
Date: September 25, 2013
Creator: Kostin, Mikhail; Mokhov, Nikolai & Niita, Koji
Partner: UNT Libraries Government Documents Department

Representative Atmospheric Plume Development for Elevated Releases

Description: An atmospheric explosion of a low-yield nuclear device will produce a large number of radioactive isotopes, some of which can be measured with airborne detection systems. However, properly equipped aircraft may not arrive in the region where an explosion occurred for a number of hours after the event. Atmospheric conditions will have caused the radioactive plume to move and diffuse before the aircraft arrives. The science behind predicting atmospheric plume movement has advanced enough that the location of the maximum concentrations in the plume can be determined reasonably accurately in real time, or near real time. Given the assumption that an aircraft can follow a plume, this study addresses the amount of atmospheric dilution expected to occur in a representative plume as a function of time past the release event. The approach models atmospheric transport of hypothetical releases from a single location for every day in a year using the publically available HYSPLIT code. The effective dilution factors for the point of maximum concentration in an elevated plume based on a release of a non-decaying, non-depositing tracer can vary by orders of magnitude depending on the day of the release, even for the same number of hours after the release event. However, the median of the dilution factors based on releases for 365 consecutive days at one site follows a power law relationship in time, as shown in Figure S-1. The relationship is good enough to provide a general rule of thumb for estimating typical future dilution factors in a plume starting at the same point. However, the coefficients of the power law function may vary for different release point locations. Radioactive decay causes the effective dilution factors to decrease more quickly with the time past the release event than the dilution factors based on a non-decaying tracer. An analytical ...
Date: March 3, 2014
Creator: Eslinger, Paul W.; Lowrey, Justin D.; McIntyre, Justin I.; Miley, Harry S. & Prichard, Andrew W.
Partner: UNT Libraries Government Documents Department

Radiation Diffusion: An Overview of Physical and Numerical Concepts

Description: An overview of the physical and mathematical foundations of radiation transport is given. Emphasis is placed on how the diffusion approximation and its transport corrections arise. An overview of the numerical handling of radiation diffusion coupled to matter is also given. Discussions center on partial temperature and grey methods with comments concerning fully implicit methods. In addition finite difference, finite element and Pert representations of the div-grad operator is also discussed
Date: January 14, 2005
Creator: Graziani, F R
Partner: UNT Libraries Government Documents Department

Implict Monte Carlo Radiation Transport Simulations of Four Test Problems

Description: Radiation transport codes, like almost all codes, are difficult to develop and debug. It is helpful to have small, easy to run test problems with known answers to use in development and debugging. It is also prudent to re-run test problems periodically during development to ensure that previous code capabilities have not been lost. We describe four radiation transport test problems with analytic or approximate analytic answers. These test problems are suitable for use in debugging and testing radiation transport codes. We also give results of simulations of these test problems performed with an Implicit Monte Carlo photonics code.
Date: August 1, 2007
Creator: Gentile, N
Partner: UNT Libraries Government Documents Department

TART 2000: A Coupled Neutron-Photon, 3-D, Combinatorial Geometry, Time Dependent, Monte Carlo Transport Code

Description: TART2000 is a coupled neutron-photon, 3 Dimensional, combinatorial geometry, time dependent Monte Carlo radiation transport code. This code can run on any modern computer. It is a complete system to assist you with input Preparation, running Monte Carlo calculations, and analysis of output results. TART2000 is also incredibly FAST; if you have used similar codes, you will be amazed at how fast this code is compared to other similar codes. Use of the entire system can save you a great deal of time and energy. TART2000 is distributed on CD. This CD contains on-line documentation for all codes included in the system, the codes configured to run on a variety of computers, and many example problems that you can use to familiarize yourself with the system. TART2000 completely supersedes all older versions of TART, and it is strongly recommended that users only use the most recent version of TART2000 and its data files.
Date: November 22, 2000
Creator: Cullen, D.E
Partner: UNT Libraries Government Documents Department

Simulations of implosions with a 3D, parallel, unstructured-grid, radiation-hydrodynamics code

Description: An unstructured-grid, radiation-hydrodynamics code is used to simulate implosions. Although most of the problems are spherically symmetric, they are run on 3D, unstructured grids in order to test the code�s ability to maintain spherical symmetry of the converging waves. Three problems, of increasing complexity, are presented. In the first, a cold, spherical, ideal gas bubble is imploded by an enclosing high pressure source. For the second, we add non-linear heat conduction and drive the implosion with twelve laser beams centered on the vertices of an icosahedron. In the third problem, a NIF capsule is driven with a Planckian radiation source.
Date: December 28, 1998
Creator: Kaiser, T. B.; Milovich, J. L.; Prasad, M. K.; Rathkopf, J. & Shestakov, A. I.
Partner: UNT Libraries Government Documents Department

Utilization of Monte Carlo Calculations in Radiation Transport Analyses to Support the Design of the U.S. Spallation Neutron Source (SNS)

Description: The Department of Energy (DOE) has given the Spallation Neutron Source (SNS) project approval to begin Title I design of the proposed facility to be built at Oak Ridge National Laboratory (ORNL) and construction is scheduled to commence in FY01 . The SNS initially will consist of an accelerator system capable of delivering an {approximately}0.5 microsecond pulse of 1 GeV protons, at a 60 Hz frequency, with 1 MW of beam power, into a single target station. The SNS will eventually be upgraded to a 2 MW facility with two target stations (a 60 Hz station and a 10 Hz station). The radiation transport analysis, which includes the neutronic, shielding, activation, and safety analyses, is critical to the design of an intense high-energy accelerator facility like the proposed SNS, and the Monte Carlo method is the cornerstone of the radiation transport analyses.
Date: October 23, 2000
Creator: Johnson, J.O.
Partner: UNT Libraries Government Documents Department

DISPERSION ANALYSIS OF RADIATION/THERMAL FRONTS WITH FULL RESOLVED SPECTRAL OPACITY VARIATION.

Description: The radiation transport and linearized thermal energy equations have been analyzed to find the temporal dependence of the component modes in a radiation/thermal front. The fully resolved spectral variation of the opacity as a function of energy, as well as the exact time and angular dependence, is treated in this work. As we are able to study arbitrarily complicated opacity spectra, we stress the importance of the new results as a check on the effect of using opacity averages.
Date: December 1, 2000
Creator: AUER, L. & LOWRIE, R.
Partner: UNT Libraries Government Documents Department

Use of the continuity equation for electromagnetic energy flow to describe radiation transport

Description: The continuity equation for electromagnetic (EM) energy flow is used to describe radiation flow in the transport regime. The scheme of a discrete representation of H<sub>z</sub> and a stochastic representation of H<sub>x</sub>, H<sub>y</sub> gives an effectively continuous representation of directed energy in the x-y plane, such that the ray effect of transport theory is absent. Since the in-plane amplitudes are generated at each time step, it is necessary to store only the perpendicular amplitudes and the results appear to be robust with respect to the coarse of this discretization.
Date: February 5, 1999
Creator: Ritchie, A B
Partner: UNT Libraries Government Documents Department

Benchmarking Heavy Ion Transport Codes FLUKA, HETC-HEDS MARS15, MCNPX, and PHITS

Description: Powerful accelerators such as spallation neutron sources, muon-collider/neutrino facilities, and rare isotope beam facilities must be designed with the consideration that they handle the beam power reliably and safely, and they must be optimized to yield maximum performance relative to their design requirements. The simulation codes used for design purposes must produce reliable results. If not, component and facility designs can become costly, have limited lifetime and usefulness, and could even be unsafe. The objective of this proposal is to assess the performance of the currently available codes – PHITS, FLUKA, MARS15, MCNPX, and HETC-HEDS – that could be used for design simulations involving heavy ion transport. We plan to access their performance by performing simulations and comparing results against experimental data of benchmark quality. Quantitative knowledge of the biases and the uncertainties of the simulations is essential as this potentially impacts the safe, reliable and cost effective design of any future radioactive ion beam facility. Further benchmarking of heavy-ion transport codes was one of the actions recommended in the “Report of the 2003 RIA R&D Workshop".
Date: June 7, 2013
Creator: Ronningen, Reginald Martin; Remec, Igor & Heilbronn, Lawrence H.
Partner: UNT Libraries Government Documents Department

Visualization of a Deterministic Radiation Transport Model Using Standard Visualization Tools

Description: Output from a deterministic radiation transport code running on a CRAY SV1 is imported into a standard distributed, parallel, visualization tool for analysis. Standard output files, consisting of tetrahedral meshes, are imported to the visualization tool through the creation of a application specific plug-in module. Visualization samples are included, providing visualization of steady state results. Different plot types and operators are utilized to enhance the analysis and assist in reporting the results of the analysis.
Date: May 1, 2004
Creator: Galbraith, James A. & Greenwade, L. Eric
Partner: UNT Libraries Government Documents Department

Experiences in the Performance Analysis and Optimization of a Deterministic Radiation Transport Code on the Cray SV1

Description: The Attila radiation transport code, which solves the Boltzmann neutron transport equation on three-dimensional unstructured tetrahedral meshes, was ported to a Cray SV1. Cray&#39;s performance analysis tools pointed to two subroutines that together accounted for 80%-90% of the total CPU time. Source code modifications were performed to enable vectorization of the most significant loops, to correct unfavorable strides through memory, and to replace a conjugate gradient solver subroutine with a call to the Cray Scientific Library. These optimizations resulted in a speedup of 7.79 for the INEEL&#39;s largest ATR model. Parallel scalability of the OpenMP version of the code is also discussed, and timing results are given for other non-vector platforms.
Date: May 1, 2004
Creator: Cebull, Peter
Partner: UNT Libraries Government Documents Department

Hierarchical Adaptive Solution of Radiation Transport Problems on Unstructured Grids

Description: Computational radiation transport has steadily gained acceptance in the last decade as a viable modeling tool due to the rapid advancements in computer software and hardware technologies. It can be applied for the analysis of a wide range of problems which arise in nuclear reactor physics, medical physics, atmospheric physics, astrophysics and other areas of engineering physics. However, radiation transport is an extremely chanllenging computational problem since the governing equation is seven-deimensional (3 in space, 2 in direction, 1 in energy, and 1 in time) with a high degree of coupleing betwen these variables. If not careful, this relatively large number of independent variables when discretized can potentially lead to sets of linear equations of intractable size. Though parallel computing has allowed the solution of very large problems, avaliable computational resources will always be finite due to the fact that every more sophisticated multiphysics models are being demanded by industry. There is thus the pressing requirement to optimize the discretizations so as to minimize the effort and maximize the accuracy.
Date: June 30, 2008
Creator: Oliveira, Dr. Cassiano R. E de
Partner: UNT Libraries Government Documents Department

Hydrodynamic and Spectral Simulations of HMXB Winds

Description: We describe preliminary results of a global model of the radiatively-driven photoionized wind and accretion flow of the high-mass X-ray binary Vela X-1. The full model combines FLASH hydrodynamic calculations, XSTAR photoionization calculations, HULLAC atomic data, and Monte Carlo radiation transport. We present maps of the density, temperature, velocity, and ionization parameter from a FLASH two-dimensional time-dependent simulation of Vela X-1, as well as maps of the emissivity distributions of the X-ray emission lines.
Date: March 30, 2007
Creator: Mauche, C W; Liedahl, D A; Akiyama, S & Plewa, T
Partner: UNT Libraries Government Documents Department

Dipole radiation from a cylindrical hole in the earth.

Description: This report examines the problem of an antenna radiating from a cylindrical hole in the earth and the subsequent far-zone field produced in the upper air half space. The approach used for this analysis was to first examine propagation characteristics along the hole for surrounding geologic material properties. Three cases of sand with various levels of moisture content were considered as the surrounding material to the hole. For the hole diameters and sand cases examined, the radiation through the earth medium was found to be the dominant contribution to the radiation transmitted through to the upper half-space. In the analysis presented, the radiation from a vertical and a horizontal dipole source within the hole is used to determine a closed-form expression for the radiation in the earth medium which represents a modified element factor for the source and hole combination. As the final step, the well-known results for a dipole below a half space, in conjunction with the use of Snell's law to transform the modified element factor to the upper half space, determine closed-form expressions for the far-zone radiated fields in the air region above the earth.
Date: August 1, 2005
Creator: Warne, Larry Kevin; Johnson, William Arthur & Basilio, Lorena I.
Partner: UNT Libraries Government Documents Department

Variational reactivity estimates: new analyses and new results

Description: A modified form of the variational estimate of the reactivity worth ofa perturbation was previously developed to extend the range of applicability of variational perturbation theory for perturbations leading to negative reactivity worths. Recent numerical results challenged the assumptions behind the modified form. In this paper, more results are obtained, leading to the conclusion that sometimes the modified form extends the range ofapplicability of variational perturbation theory for positive reactivity worths as well, and sometimes the standard variational form is more accurate for negative-reactivity perturbations. In addition, this paper proves that using the exact generalized adjoint function would lead to an inaccurate variational reactivity estimate when the error in the first-order estimate is large; the standard generalized adjoint function, an approximation to the exact one, leads to Lore accurate results. This conclusion is also demonstrated numerically. Transport calculations use the PARTISN multi group discrete ordinates code
Date: January 1, 2009
Creator: Favorite, Jeffrey A
Partner: UNT Libraries Government Documents Department

Using MCNPX for space applications

Description: The Los Alamos National Laboratory Monte Carlo N-Particle, eXtended-energy radiation transport code MCNPX is rapidly becoming an international standard for a wide spectrum of high-energy radiation transport applications. One such application includes the study of gamma rays produced by cosmic-ray interactions within a planetary surface. Such studies can be used to determine surface elemental composition. This paper presents various MCNPX enhancements that make these gamma ray spectroscopy (GRS) simulations possible, gives elemental spectra results for a specific lunar material, provides a comparison between various high-energy physics models, and shows results of an elemental least squares analysis using Lunar Prospector measurements. The analysis documented here demonstrates the usefulness of MCNPX in planetary gamma ray spectroscopy. Furthermore, new MCNPX features developed over the course of this analysis will prove extremely useful for other applications as well. Comparisons of MCNPX results to lunar GRS measurements are better than expected and have lead to the identification of spectral features previously unknown. Through a library least squares analysis, these simulation spectra have resulted in detailed maps of lunar composition.
Date: January 1, 2002
Creator: McKinney, G. W. (Gregg W.); Hendricks, J. S. (John S.); Waters, L. S. (Laurie S.) & Prettyman, T. H. (Thomas H.)
Partner: UNT Libraries Government Documents Department

MCNPX version 2.5.c

Description: MCNPX is a Fortran 90 Monte Carlo radiation transport computer code that transports all particles at all energies. It is a superset of MCNP4C3, and has many capabilities beyond MCNP4C3. These capabilities are summarized along with their quality guarantee and code availability. Then the user interface changes from MCNP are described. Finally, the n.ew capabilities of the latest version, MCNPX 2.5.c, are documented. Future plans and references are also provided.
Date: January 1, 2003
Creator: Hendricks, J. S. (John S.)
Partner: UNT Libraries Government Documents Department

Piecewise linear discretization of Symbolic Implicit Monte Carlo radiation transport in the difference formulation

Description: We describe a Monte Carlo solution for time dependent photon transport, in the difference formulation with the material in local thermodynamic equilibrium (LTE), that is piecewise linear in its treatment of the material state variable. Our method employs a Galerkin solution for the material energy equation while using Symbolic Implicit Monte Carlo (SIMC) to solve the transport equation. In constructing the scheme, one has the freedom to choose between expanding the material temperature, or the equivalent black body radiation energy density at the material temperature, in terms of finite element basis functions. The former provides a linear treatment of the material energy while the latter provides a linear treatment of the radiative coupling between zones. Subject to the conditional use of a lumped material energy in the vicinity of strong gradients, possible with a linear treatment of the material energy, our approach provides a robust solution for time dependent transport of thermally emitted radiation that can address a wide range of problems. It produces accurate results in the diffusion limit.
Date: November 15, 2005
Creator: Brooks III, E D; Szoke, A & Peterson, J L
Partner: UNT Libraries Government Documents Department

Transport Test Problems for Hybrid Methods Development

Description: This report presents 9 test problems to guide testing and development of hybrid calculations for the ADVANTG code at ORNL. These test cases can be used for comparing different types of radiation transport calculations, as well as for guiding the development of variance reduction methods. Cases are drawn primarily from existing or previous calculations with a preference for cases which include experimental data, or otherwise have results with a high level of confidence, are non-sensitive, and represent problem sets of interest to NA-22.
Date: December 28, 2011
Creator: Shaver, Mark W.; Miller, Erin A.; Wittman, Richard S. & McDonald, Benjamin S.
Partner: UNT Libraries Government Documents Department

Compendium of Material Composition Data for Radiation Transport Modeling

Description: Introduction Meaningful simulations of radiation transport applications require realistic definitions of material composition and densities. When seeking that information for applications in fields such as homeland security, radiation shielding and protection, and criticality safety, researchers usually encounter a variety of materials for which elemental compositions are not readily available or densities are not defined. Publication of the Compendium of Material Composition Data for Radiation Transport Modeling, Revision 0, in 2006 was the first step toward mitigating this problem. Revision 0 of this document listed 121 materials, selected mostly from the combined personal libraries of staff at the Pacific Northwest National Laboratory (PNNL), and thus had a scope that was recognized at the time to be limited. Nevertheless, its creation did provide a well-referenced source of some unique or hard-to-define material data in a format that could be used directly in radiation transport calculations being performed at PNNL. Moreover, having a single common set of material definitions also helped to standardize at least one aspect of the various modeling efforts across the laboratory by providing separate researchers the ability to compare different model results using a common basis of materials. The authors of the 2006 compendium understood that, depending on its use and feedback, the compendium would need to be revised to correct errors or inconsistencies in the data for the original 121 materials, as well as to increase (per users suggestions) the number of materials listed. This 2010 revision of the compendium has accomplished both of those objectives. The most obvious change is the increased number of materials from 121 to 372. The not-so-obvious change is the mechanism used to produce the data listed here. The data listed in the 2006 document were compiled, evaluated, entered, and error-checked by a group of individuals essentially by hand, providing no library file ...
Date: March 4, 2011
Creator: McConn, Ronald J.; Gesh, Christopher J.; Pagh, Richard T.; Rucker, Robert A. & Williams III, Robert
Partner: UNT Libraries Government Documents Department

Hydra modeling of experiments to study ICF capsule fill hole dynamics using surrogate targets

Description: In this section the results of HYDRA [1] design simulations will be discussed. The simulations were conducted in two dimensional, RZ geometry, with the fill tube on axis. The radiation transport was treated in the diffusion approximation using 15 energy groups. Opacities were calculated. The equations of state (EOS) for all materials used were from a combined analytic/Thomas-Fermi EOS which uses a modified Cowan model for the ion EOS, and uses a scaled Thomas-Fermi table for the electron EOS.
Date: August 27, 2007
Creator: Elliott, J B
Partner: UNT Libraries Government Documents Department

Simulations of the radiation-flow within a silica-aerogel target

Description: We propose to field a series of experiments to study the flow of radiation through silica-aerogel targets. The soft x-rays are generated by the Z-machine at Sandia National Laboratories. We have completed simulations of the experiments using 2-D Lagrangian and Eulerian codes. The results of the calculations for one of the targets are presented here.
Date: January 1, 2002
Creator: Aubrey, J. B. (Joysree B.); Wood, B. P. (Blake P.); Peterson, D. L. (Darrell L.) & Kyrala, George A.
Partner: UNT Libraries Government Documents Department