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Engineers at Los Alamos National Laboratory (LANL) are currently developing capabilities, in cooperation with Southwest Research Institute, to provide reliability-based structural evaluation techniques for performing weapon component and system reliability assessments. The development and applications of Probabilistic Structural Analysis Methods (PSAM) is an important ingredient in the overall weapon reliability assessments. Focus, herein, is placed on the uncertainty associated with the structural response of an explosive actuated valve-piston assembly. The probabilistic dynamic response of the piston upon impact is evaluated through the coupling of the probabilistic code NESSUS (Numerical Evaluation of Stochastic Structures Under Stress) [1] with the non-linear structural dynamics code, ABAQUS/Explicit [2]. The probabilistic model includes variations in piston mass and geometry, and mechanical properties, such as Young's Modulus, yield strength, and flow characteristics. Finally, the probability of exceeding a specified strain limit, which is related to piston fracture, is determined.

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In 1999, the US Nuclear Regulatory Commission (NRC) tasked Argonne National Laboratory to modify the existing RESRAD and RESRAD-BUILD codes to perform probabilistic, site-specific dose analysis for use with the NRC's Standard Review Plan for demonstrating compliance with the license termination rule. The RESRAD codes have been developed by Argonne to support the US Department of Energy's (DOEs) cleanup efforts. Through more than a decade of application, the codes already have established a large user base in the nation and a rigorous QA support. The primary objectives of the NRC task are to: (1) extend the codes' capabilities to include probabilistic analysis, and (2) develop parameter distribution functions and perform probabilistic analysis with the codes. The new codes also contain user-friendly features specially designed with graphic-user interface. In October 2000, the revised RESRAD (version 6.0) and RESRAD-BUILD (version 3.0), together with the user's guide and relevant parameter information, have been developed and are made available to the general public via the Internet for use.

Long-term bio-monitoring of avian communities have been initiated, but they often lack a management component. Integration of the managers needs at an early stage is suggested as a means to increase the use of the data. Variation in community structure is important in understanding impacts. In addition, reference site must be carefully selected.

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Experienced experimentalists have gone through the process of attempting to identify a final set of modal parameters from several different sets of extracted parameters. Usually, this is done by visually examining the mode shapes. With the advent of automated modal parameter extraction algorithms such as SMAC (Synthesize Modes and Correlate), very accurate extractions can be made to high frequencies. However, this process may generate several hundred modes that then must be consolidated into a final set of modal information. This has motivated the authors to generate a set of tools to speed the process of consolidating modal parameters by mathematical (instead of visual) means. These tools help quickly identify the best modal parameter extraction associated with several extractions of the same mode. The tools also indicate how many different modes have been extracted in a nominal frequency range and from which references. The mathematics are presented to achieve the best modal extraction of multiple modes at the same nominal frequency. Improvements in the SMAC graphical user interface and database are discussed that speed and improve the entire extraction process.

In this paper we examined the consequences of improving the nuclear reaction library on our simulations of TNRs on 1.25M, WD and 1.35M, WDS. We have found that the changes in the rates have affected the nucleosynthesis predictions of our calculations but not, to any great extent, the gross features. In addition, we have used a lower mass accretion rate than in our previous studies in order to accrete (and eject) more material. This has, as expected, caused the peak values of some important parameters to increase over our previous studies at the same WD mass. However, because some important reaction rates have declined in the new compilation this has not increased the abundances for nuclei above aluminum and, in fact, they have declined while the abundances of both {sup 26}Al and {sup 27}Al have increased at both WD masses. In contrast, the abundance of {sup 22}Na has declined at both WD masses over the values predicted in our earlier work. This has important implications with respect to predictions of the observability of novae with INTEGRAL.

The Los Alamos National Laboratory (LANL) Monte Carlo N-Particle radiation transport code, MCNP, has become an international standard for a wide spectrum of neutron, photon, and electron radiation transport applications. The latest version of the code, MCNP 4C, was released to the Radiation Safety Information Computational Center (RSICC) in February 2000. This paper describes the code development philosophy, new features and capabilities, applicability to various problems, and future directions.

The red cockaded woodpecker has been intensively studied since 1985 when the population was on the verge of extinction. The population decline is primarily the result of timber harvesting prior to 1950 and restricted burning. Construction of artificial cavities, translocations, competitor control, and removal of hardwood mid-story has provided suitable habitat. Since 1985, the population has increased from 4 to 99 birds. A GIS model is being developed to simulate the development of habitat at SRS in relation to management and existing vegetation.

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The Million Solar Roofs Initiative has motivated a renewed interest in the development of utility interconnected photovoltaic (UIPV) inverters. Government-sponsored programs (PVMaT, PVBONUS) and competition among utility interconnected inverter manufacturers have stimulated innovations and improved the performance of existing technologies. With this resurgence, Sandia National Laboratories (SNL) has developed a program to assist industry initiatives to overcome barriers to UIPV inverters. In accordance with newly adopted IEEE 929-2000, the utility interconnected PV inverters are required to cease energizing the utility grid when either a significant disturbance occurs or the utility experiences an interruption in service. Compliance with IEEE 929-2000 is being widely adopted by utilities as a minimum requirement for utility interconnection. This report summarizes work done at the SNL balance-of-systems laboratory to support the development of IEEE 929-2000 and to assist manufacturers in meeting its requirements.

One of the key elements of the Stochastic Finite Element Method, namely the polynomial chaos expansion, has been utilized in a nonlinear shock and vibration application. As a result, the computed response was expressed as a random process, which is an approximation to the true solution process, and can be thought of as a generalization to solutions given as statistics only. This approximation to the response process was then used to derive an analytically-based design specification for component shock response that guarantees a balanced level of marginal reliability. Hence, this analytically-based reference SRS might lead to an improvement over the somewhat ad hoc test-based reference in the sense that it will not exhibit regions of conservativeness. nor lead to overtesting of the design.

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Molecular dynamics simulations are used to help design new experiments by modeling the cooling of small numbers of trapped multiply charged ions by Coulomb interactions with laser-cooled Be{sup +} ions. A Verlet algorithm is used to integrate the equations of motion of two species of point ions interacting in an ideal Penning trap. We use a time step short enough to follow the cyclotron motion of the ions. Axial and radial temperatures for each species are saved periodically. Direct heating and cooling of each species in the simulation can be performed by periodically rescaling velocities. Of interest are Fe{sup 11+} due to a EUV-optical double resonance for imaging and manipulating the ions, and Ca{sup 14+} since a ground state fine structure transition has a convenient wavelength in the tunable laser range.

This research presents a new method to improve analytical model fidelity for non-linear systems. The approach investigates several mechanisms to assist the analyst in updating an analytical model based on experimental data and statistical analysis of parameter effects. The first is a new approach at data reduction called feature extraction. This is an expansion of the update metrics to include specific phenomena or character of the response that is critical to model application. This is an extension of the classical linear updating paradigm of utilizing the eigen-parameters or FRFs to include such devices as peak acceleration, time of arrival or standard deviation of model error. The next expansion of the updating process is the inclusion of statistical based parameter analysis to quantify the effects of uncertain or significant effect parameters in the construction of a meta-model. This provides indicators of the statistical variation associated with parameters as well as confidence intervals on the coefficients of the resulting meta-model, Also included in this method is the investigation of linear parameter effect screening using a partial factorial variable array for simulation. This is intended to aid the analyst in eliminating from the investigation the parameters that do not have a significant variation …

Dispersion strengthened copper, known by the trade name GLIDCOP{reg_sign}, has found various applications in accelerator designs. Glidcop has material properties similar to OFE copper, such as thermal and electrical conductivity. Unlike OFE, however, Glidcop has yield and ultimate strengths equivalent to those of mild-carbon steel, making it a good structural material. This paper covers some accelerator components fabricated with Glidcop, material properties measured from room to brazing temperatures, and a furnace-brazing process that has produced good, consistent results with Glidcop.

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We describe the design, construction and performance of an instrument designed to monitor compliance with future arms control treaties. By monitoring changes in the gamma-ray spectrum emitted by a stored nuclear weapon, our device is able to sense perturbations in the contents of a weapon storage container that would indicate treaty non-compliance. Our instrument (dubbed the Radiation Continuity Checker or RCC) is designed to detect significant perturbations in the gamma-ray spectra (indicative of tampering) while storing no classified information about the weapon, and having a negligible ''false alarm rate''. In this paper we describe the technical details of two prototype instruments and describe the strategies we have adopted to perform signal processing in these instruments. Our first instrument prototype uses a scintillation spectrometer and a massive tungsten alloy collimator to reject the gamma-ray background. Our second prototype instrument makes use of an active collimation scheme employing a multiple detector Compton scatter approach to reject background radiation. The signal processing method we employ uses linear algorithms applied pulse by pulse. This eliminates the need for storage of pulse height spectra, which are in many cases classified.