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VisIt: a component based parallel visualization package

Description: We are currently developing a component based, parallel visualization and graphical analysis tool for visualizing and analyzing data on two- and three-dimensional (20, 30) meshes. The tool consists of three primary components: a graphical user interface (GUI), a viewer, and a parallel compute engine. The components are designed to be operated in a distributed fashion with the GUI and viewer typically running on a high performance visualization server and the compute engine running on a large parallel platform. The viewer and compute engine are both based on the Visualization Toolkit (VTK), an open source object oriented data manipulation and visualization library. The compute engine will make use of parallel extensions to VTK, based on MPI, developed by Los Alamos National Laboratory in collaboration with the originators of P K . The compute engine will make use of meta-data so that it only operates on the portions of the data necessary to generate the image. The meta-data can either be created as the post-processing data is generated or as a pre-processing step to using VisIt. VisIt will be integrated with the VIEWS' Tera-Scale Browser, which will provide a high performance visual data browsing capability based on multi-resolution techniques.
Date: December 18, 2000
Creator: Ahern, S; Bonnell, K; Brugger, E; Childs, H; Meredith, J & Whitlock, B
Partner: UNT Libraries Government Documents Department

"Spall-4:" An Energy-Based Model for Spall

Description: An energy-dependent bond-breaking model for material failure is described. The logic of the scheme has its roots in that of the Cochran- Banner spall model [Cochran and Banner, 1977], but significant differences have been introduced. Material zones undergoing tensile stress incur damage according to an exponential expression related to the familiar Maxwell-Boltzmann distribution. A scheme for converting the damage calculated in specified contiguous zones of the mesh into a 'strength factor' for each subject zone is included as a means to account for statistical variability in the location and extent of the failure region. A dynamical healing algorithm is also described. To date the method has been tried only in 1-D slab symmetry, but it is intended for general use in mesh-zoned hydro codes of any dimensionality.
Date: November 24, 2004
Creator: Zimmerman, I H
Partner: UNT Libraries Government Documents Department

Nuclear explosive safety study process

Description: Nuclear explosives by their design and intended use require collocation of high explosives and fissile material. The design agencies are responsible for designing safety into the nuclear explosive and processes involving the nuclear explosive. The methodology for ensuring safety consists of independent review processes that include the national laboratories, Operations Offices, Headquarters, and responsible Area Offices and operating contractors with expertise in nuclear explosive safety. A NES Study is an evaluation of the adequacy of positive measures to minimize the possibility of an inadvertent or deliberate unauthorized nuclear detonation, high explosive detonation or deflagration, fire, or fissile material dispersal from the pit. The Nuclear Explosive Safety Study Group (NESSG) evaluates nuclear explosive operations against the Nuclear Explosive Safety Standards specified in DOE O 452.2 using systematic evaluation techniques. These Safety Standards must be satisfied for nuclear explosive operations.
Date: January 1, 1997
Partner: UNT Libraries Government Documents Department

A new paradigm to establish the safety basis for nuclear explosives operations

Description: The U. S. Department of Energy (DOE) has recognized that safety assurance requires a balance of institutional and engineering approaches as part of an ongoing safety process. This recognition formed the basis for a new approach to nuclear explosive safety with a focus on the inherent value of the examination process, as opposed to an absolute justification of the nuclear explosive operation against some preddined acceptance criteria. This new approach to safety is reflected in recent DOE Orders and Standards in that there is no requirement that quantitative risk assessment or risk quantification be used in meeting requirements. Furthermore, there is no requirement to compare hazard and accident analysis results against numerical acceptance criteria. This paper discusses the evolution of the DOE nuclear explosive safety orders and compares those with facility safety requirements. The DOE nuclear explosive safety process is examined, and an example application is discussed with emphasis on identification of safety measures and controls.
Date: September 13, 1998
Creator: Fischer, Stewart R., Clement, Steven, Stack, Desmond W.
Partner: UNT Libraries Government Documents Department

Turbulent mix experiments and simulations

Description: Hydrodynamic instabilities produce material mixing that can significantly degrade weapons performance. We investigate the Richtmyer-Meshkov (RM) and Rayleigh-Taylor (RT) instabilities in the turbulent regime in two experimental venues. RM experiments are conducted on the Nova laser with strong radiatively driven shocks (Mach > 20) in planar, two fluid targets. Interfacial perturbations are imposed with single sinusoidal modes to test linear theory and with three dimensional (3D) random modes to produce turbulent mix. RT experiments are conducted on a new facility, the Linear Electric Motor (LEM), in which macroscopic fluids are accelerated with arbitrary temporal profiles. This allows detailed diagnosis of the turbulence over a wide range of conditions. The Nova experiments study the high compression regime whereas the LEM experiments are incompressible. The results are compared to hydrodynamic simulations with the arbitrary Lagrangian-Eulerian code (CALE). The goal is to develop and test engineering models of mix.
Date: August 1, 1995
Creator: Dimonte, G.; Schneider, M. & Frerking, C.E.
Partner: UNT Libraries Government Documents Department

The Use of Nuclear Explosives To Disrupt or Divert Asteroids

Description: Nuclear explosives are a mature technology with well-characterized effects. Proposed utilizations include a near asteroid burst to ablate surface material and nudge the body to a safer orbit, or a direct sub-surface burst to fragment the body. For this latter method, previous estimates suggest that for times as short as 1000 days, over 99.999% of the material is diverted, and no longer impacts the Earth, a huge mitigation factor. To better understand these possibilities, we have used a multidimensional radiation/hydrodynamics code to simulate sub-surface and above surface bursts on an inhomogeneous, 1 km diameter body with an average density of 2 g/cc. The body, or fragments (up to 750,000) are then tracked along 4 representative orbits to determine the level of mitigation achieved. While our code has been well tested in simulations on terrestrial structures, the greatest uncertainty in these results lies in the input. These results, particularly the effort to nudge a body into a different orbit, are dependant on NEO material properties, like the dissipation of unconsolidated material in a low gravity environment, as well as the details on an individual body's structure. This problem exists in simulating the effect of any mitigation technology. In addition to providing an greater understanding of the results of applying nuclear explosives to NEO-like bodies, these simulations suggest what must be learned about these bodies to improve the predictive capabilities. Finally, we will comment on some of the popular misinformation abounding about the utility of nuclear explosives.
Date: February 20, 2007
Creator: Dearborn, D. S.; Patenaude, S. & Managan, R. A.
Partner: UNT Libraries Government Documents Department

Using the Schur Complement to Reduce Runtime in KULL's Magnetic Diffusion Package

Description: Recently a Resistive Magnetohydrodynamics (MHD) package has been added to the KULL code. In order to be compatible with the underlying hydrodynamics algorithm, a new sub-zonal magnetics discretization was developed that supports arbitrary polygonal and polyhedral zones. This flexibility comes at the cost of many more unknowns per zone - approximately ten times more for a hexahedral mesh. We can eliminate some (or all, depending on the dimensionality) of the extra unknowns from the global matrix during assembly by using a Schur complement approach. This trades expensive global work for cache-friendly local work, while still allowing solution for the full system. Significant improvements in the solution time are observed for several test problems.
Date: December 15, 2010
Creator: Brunner, T A & Kolev, T V
Partner: UNT Libraries Government Documents Department

3-D Combinatorial Geometry in the MERCURY Monte Carlo Particle Transport Code

Description: Lawrence Livermore National Laboratory is in the process of developing a new Monte Carlo Particle Transport code named MERCURY. This new code features a 3-D Combinatorial Geometry tracking algorithm. This paper details some of the characteristics of this Monte Carlo tracker
Date: September 27, 2004
Creator: Greenman, G
Partner: UNT Libraries Government Documents Department

DUNE - a granular flow code

Description: DUNE was designed to accurately model the spectrum of granular. Granular flow encompasses the motions of discrete particles. The particles are macroscopic in that there is no Brownian motion. The flow can be thought of as a dispersed phase (the particles) interacting with a fluid phase (air or water). Validation of the physical models proceeds in tandem with simple experimental confirmation. The current development team is working toward the goal of building a flexible architecture where existing technologies can easily be integrated to further the capability of the simulation. We describe the DUNE architecture in some detail using physics models appropriate for an imploding liner experiment.
Date: November 23, 2004
Creator: Slone, D M; Cottom, T L & Bateson, W B
Partner: UNT Libraries Government Documents Department

New 193Ir(n,n'y)193mIr Evaluated Nuclear Cross Sections for Radchem

Description: New measurements performed with the GEANIE {gamma}-ray detector array at LANSCE, and theoretical calculations performed by T-16 have improved the accuracy with which the energy-dependent cross section for production of the long-lived isomer in 193Ir is known. Comparisons with critical assemblies data show excellent agreement. Evaluation work is nearly complete to enable the use of the new data in applied calculations.
Date: January 4, 2005
Creator: Nelson, R O; Fotiades, N; Devlin, M; Talou, P; Chadwick, M B; MacFarlane, R et al.
Partner: UNT Libraries Government Documents Department

A New Vista in Scientific Data Management

Description: This paper examines the use of an in-core database in place of traditional data structures in two ASC codes. Results so far indicate a dramatic reduction in code, coupled with an increase in functionality. Performance impact has been around one percent for the majority of problems tested. Debugging has been the major roadblock thus far, and a portable browser tool has been written that will soon work with a variety of debuggers.
Date: December 13, 2004
Creator: Keasler, J
Partner: UNT Libraries Government Documents Department

Remote Monitoring Transparency Program

Description: The objective of the Remote Monitoring Transparency Program is to evaluate and demonstrate the use of remote monitoring technologies to advance nonproliferation and transparency efforts that are currently being developed by Russia and the United States without compromising the national security to the participating parties. Under a lab-to-lab transparency contract between Sandia National Laboratories (SNL) and the Kurchatov Institute (KI RRC), the Kurchatov Institute will analyze technical and procedural aspects of the application of remote monitoring as a transparency measure to monitor inventories of direct- use HEU and plutonium (e.g., material recovered from dismantled nuclear weapons). A goal of this program is to assist a broad range of political and technical experts in learning more about remote monitoring technologies that could be used to implement nonproliferation, arms control, and other security and confidence building measures. Specifically, this program will: (1) begin integrating Russian technologies into remote monitoring systems; (2) develop remote monitoring procedures that will assist in the application of remote monitoring techniques to monitor inventories of HEU and Pu from dismantled nuclear weapons; and (3) conduct a workshop to review remote monitoring fundamentals, demonstrate an integrated US/Russian remote monitoring system, and discuss the impacts that remote monitoring will have on the national security of participating countries.
Date: August 1, 1996
Creator: Sukhoruchkin, V.K.; Shmelev, V.M. & Roumiantsev, A.N.
Partner: UNT Libraries Government Documents Department

Plowshare sequential device test

Description: For over a year we have been advocating the development of a hardened or ruggedized version of Diamond which will be suitable for sequential detonation of multiple explosives in one emplacement hole. A Plowshare-sponsored device development test, named `Yacht` is proposed for execution in Area 15 at the Nevada Test Site [NTS] in late September 1972. The test is designed to evaluate the ability of a ruggedized Diamond-type explosive assembly to withstand the effects of an adjacent nuclear detonation in the same emplacement hole and then be sequentially fired. The objectives and experimental plan for this concept is provided.
Date: August 2, 1971
Creator: Ballou, L. B.
Partner: UNT Libraries Government Documents Department

Discussion of nuclear explosive operation process changes generated by a preliminary hazard assessment

Description: Hazard assessments (HAs) are being used to support the US Department of Energy (DOE) Integrated Safety Process (SS-21), Nuclear Explosive Safety Study Group (NESSG), and Environmental Safety and Health (ES and H) initiatives. The HAs are used to identify hazards associated with nuclear explosive operations involving tooling and procedural processes. In general, a HA is a formal, systematic, in-depth method for evaluating a set of possible accident scenarios associated with a process. Two assessments of a nuclear explosive surveillance process have been performed or are in progress: (1) a preliminary HA of current operations to focus efforts on maximizing safety improvements during subsequent process redesign and track overall improvement following process redesign (completed) and (2) a rolling assessment of hazards present in conceptual solutions and solutions to improve safety (in progress). The preliminary HA was used to focus the process design teams on problem areas. The rolling assessment is evaluating how well problem areas were eliminated or mitigated. This paper summarizes the preliminary HA, how it focused the design teams on problem areas found by the assessment, and the rolling assessment of solutions generated by the process design team.
Date: September 1998
Creator: O`Brien, D. & Fischer, S. R.
Partner: UNT Libraries Government Documents Department

An evaluation of the effectiveness of the US Department of Energy Integrated Safety Process (SS-21) for Nuclear Explosive Operations using quantitative hazard analysis

Description: This paper evaluates the effectiveness of the US Department of Energy Integrated Safety Process or ``Seamless Safety (SS-21)`` program for reducing risk associated with nuclear explosive operations. A key element in the Integrated Safety Process is the use of hazard assessment techniques to evaluate process design changes in parallel or concurrently with process design and development. This concurrent hazard assessment method recently was employed for the B61-0, 2 & 5 and W69 nuclear explosive dismantlement activities. This paper reviews the SS-21 hazard assessment process and summarizes the results of the concurrent hazard assessments performed for the B61 and W69 dismantlement programs. Comparisons of quantitative hazard assessment results before and after implementation of the SS-21 design process shed light on the effectiveness of the SS-21 program for achieving risk reduction.
Date: March 1, 1996
Creator: Fischer, S.R.; Konkel, H.; Bott, T.; Eisenhawer, S.; Auflick, J.; Houghton, K. et al.
Partner: UNT Libraries Government Documents Department

Deflection of large near-earth objects

Description: The Earth is periodically hit by near Earth objects (NEOs) ranging in size from dust to mountains. The small ones are a useful source of information, but those larger than about 1 km can cause global damage. The requirements for the deflection of NEOs with significant material strength are known reasonably well; however, the strength of large NEOs is not known, so those requirements may not apply. Meteor impacts on the Earth`s atmosphere give some information on strength as a function of object size and composition. This information is used here to show that large, weak objects could also be deflected efficiently, if addressed properly.
Date: January 11, 1999
Creator: Canavan, G. H.
Partner: UNT Libraries Government Documents Department

Current limiters

Description: The current that flows between the electrical test equipment and the nuclear explosive must be limited to safe levels during electrical tests conducted on nuclear explosives at the DOE Pantex facility. The safest way to limit the current is to use batteries that can provide only acceptably low current into a short circuit; unfortunately this is not always possible. When it is not possible, current limiters, along with other design features, are used to limit the current. Three types of current limiters, the fuse blower, the resistor limiter, and the MOSFET-pass-transistor limiters, are used extensively in Pantex test equipment. Detailed failure mode and effects analyses were conducted on these limiters. Two other types of limiters were also analyzed. It was found that there is no best type of limiter that should be used in all applications. The fuse blower has advantages when many circuits must be monitored, a low insertion voltage drop is important, and size and weight must be kept low. However, this limiter has many failure modes that can lead to the loss of over current protection. The resistor limiter is simple and inexpensive, but is normally usable only on circuits for which the nominal current is less than a few tens of milliamperes. The MOSFET limiter can be used on high current circuits, but it has a number of single point failure modes that can lead to a loss of protective action. Because bad component placement or poor wire routing can defeat any limiter, placement and routing must be designed carefully and documented thoroughly.
Date: September 1, 1996
Creator: Loescher, D.H. & Noren, K.
Partner: UNT Libraries Government Documents Department

Graded approach for initiating event selection in a facility hazard analysis

Description: This paper describes a methodology for selecting initiating events or event scenarios for the hazard analysis of a new Department of Energy (DOE) facility at the Nevada Test Site for nuclear explosive operations called the Device Assembly Facility (DAF). The selection process is a very important first step in conducting the hazard analysis for the facility, which in turn may feed into a quantitative risk analysis. A comprehensive risk analysis is dependent on the identification and inclusion of a complete set of initiating events in the analysis model. A systematic and logical method of grading or screening all the potential initiating events satisfies the needs for completeness within the bounds of efficiency and practicality. By applying the graded approach to the selection of the initiating events, the task and hazard analysis was able to focus its attention on only those events having the potential to develop into credible accident scenarios. Resources were concentrated into the understanding of those scenarios, and assuring that adequate positive measures are in place to control the risk associated with them.
Date: April 1, 1998
Creator: Majumdar, K. & Altenbach, T.
Partner: UNT Libraries Government Documents Department

A versatile, high-power proton linac for accelerator driven transmutation technologies

Description: We are applying the new coupled-cavity drift-tube linac (CCDTL) to a conceptual design of a high-current, CW accelerator for transmutation applications. A 350-MHz RFQ followed by 700--MHz structures accelerates a 100-mA proton beam to I GeV. Several advantages stem from four key features: (1) a uniform focusing lattice from the start of the CCDTL at about 7 MeV to the end of the linac, (2) external location and separate mechanical support of the electromagnetic quadrupole magnets, (3) very flexible modular physics design and mechanical implementation, and (4) compact, high-frequency structures. These features help to reduce beam loss and, hence, also reduce potential radioactivation of the structure. They result in easy alignment, fast serviceability, and high beam availability. Beam funneling, if necessary, is possible at any energy after the RFQ.
Date: May 1, 1995
Creator: Billen, J.H.; Nath, S.; Stovall, J.E.; Takeda, H.; Wood, R.L. & Young, L.M.
Partner: UNT Libraries Government Documents Department

Production and dissolution of nuclear explosive melt glasses at underground test sites in the Pacific Region

Description: From 1975 to 1996 the French detonated 140 underground nuclear explosions beneath the atolls of Mururoa and Fangataufa in the South Pacific; from 1965 to 1971 the United States detonated three high yield nuclear tests beneath Amchitka Island in the Aleutian chain. Approximately 800 metric tons of basalt is melted per kiloton of nuclear yield; almost lo7 metric tons of basalt were melted in these tests. Long-lived and toxic radionuclides are partitioned into the melt glass at the time of explosion and are released by dissolution with seawater under saturated conditions. A glass dissolution model predicts that nuclear melt glasses at these sites will dissolve in lo6 to lo7 yea
Date: November 6, 1998
Creator: Bourcier, W.L. & Smith, D.K.
Partner: UNT Libraries Government Documents Department