Publications

Thin cathode coatings have been shown to be effective in suppressing pulsed breakdown in vacuum. Coatings are normally plastics, although some inorganics have been used. Thicknesses range from on the order of a micron to several mils (1 mil = 25.4 /mu/m). Pulse lengths from 10 ns to more than 1 /mu/s have been studied. 2 refs., 3 figs.

Data from an array of sixteen electric-field sensors have been used to evaluate the potential benefits to lightning warning systems of processing ''old'' data as well as data from off-site sensors. These specific topics are approached from a broad decision-theoretic viewpoint. 4 refs., 10 figs.

Low coulombic efficiencies of zinc/bromine redox batteries have been attributed to migration of bromine and negatively charged bromine moieties through the microporous separator used to separate the catholyte from the anolyte. While it has been demonstrated that improvements in coulombic efficiency can be achieved by replacing the microporous separator with a cationic ion exchange membrane, these membranes are expensive and/or not sufficiently conductive to be practicable. We have found that the rate of bromine permeation can be reduced by two orders of magnitude with minimal decreases in conductivity by impregnating commercial microporous polyethylene type separators with sulfonated polysulfone, a cationic polyelectrolyte that was developed in earlier work for other redox storage batteries. 5 refs., 1 fig., 1 tab.

The phenomenon of molten fuel-coolant interaction (FCI) is of considerable interest in many industrial processes where hot molten material may come in contact with water, including the pulp and paper, aluminum, steel, and nuclear power industries. The nature of the FCIs can range from mild film boiling, through energetic boiling, up to a violent vapor explosion. In the nuclear power industry, FCIs are of interest because of their possible consequences during hypothetical light water reactor core meltdown accidents. These interactions may occur under a variety of conditions either within the reactor vessel or in the reactor cavity. The IFCI computer code is being developed to investigate the FCI problem at large scale using a two-dimensional, four-field hydrodynamic framework and physically based models. IFCI will be capable of treating all major FCI processes in an integrated manner. The hydrodynamic method and physical models used in IFCI are discussed. Results from a test problem simulating a generic pouring mode experiment are presented. 39 refs., 10 figs., 1 tab.

Design and analysis of spacecraft power systems have been difficult to perform because of the lack of circuit level models for nonlinear inductive elements. This paper reviews some of the models which have been proposed, their limitations, and applications. An improved saturation dependent model will be described. The model has been implemented in SPICE and with a commercial circuit program and demonstrated to be satisfactory in both implementations. 3 refs., 9 figs.

Vibration testing in a centrifuge acceleration field (up to 50 gs) can be accomplished in either of two axes relative to the centrifuge acceleration with a modified, commercially available, electrodynamic shaker and the use of a specially designed orthogonal motion converter. Fixing the shaker armature axis in-line with the centrifuge arm (head towards the pivot) keeps the inertial forces on the head in the one direction which can be offset with servo controlled pneumatic bags located beneath the shaker head. Testing in an axis perpendicular to the principal axis is accomplished with the orthogonal motion converter which is driven by the shaker head. Copyright © 1989 Society of Automotive Engineers, Inc.

For estimating the global elasto-plastic structural response of critical concrete structures subjected to an aircraft crash, the time dependent impact force of a flat rigid barrier against a normally impacting aircraft was first evaluated and then the response, to the impact force, was calculated. In this approach, a significant problem was to determine the impact force for the aircraft against a rigid target. A review of the method proposed to determine the impact forces showed that all were based on analytical methods. However, in these analytical methods, there were many assumptions and many questions remained to be answered. Because of the uncertainty involved in the analytical prediction of the impact force, a full- scale aircraft impact test was performed and an extensive suite of response measurements was obtained. In this paper, these measurements are analyzed to evaluate the impact force accurately. Also, the results were used to evaluate existing analytical methods for prediction of the impact force. 7 refs., 10 figs.

The hydrostatic pressure dependence of the /beta/ molecular relaxation process of polyvinylidene fluoride (PVDF) has been investigated to 20 kbar. This relaxation is known to have a strong influence on the electrical and mechanical properties of PVDF. The observed large slowing down of the relaxation process is discussed in terms of the Vogel/endash/Fulcher equation. There is an increase in both the energy barrier to dipolar motion and the reference temperature (T/sub 0/) for the kinetic relaxation process which represents the ''static'' dipolar freezing temperature for the process.

Whether upgrading or developing a security system, investing in a solid state video recorder may prove to be quite prudent. Even though the initial cost of a solid state recorder may be more expensive, when comparing it to a disc recorder it is practically maintenance free. Thus, the cost effectiveness of a solid state video recorder over an extended period of time more than justifies the initial expense. This document illustrates the use of a solid state video recorder as a direct replacement. It replaces a mechanically driven disc recorder that existed in a synchronized video recording system. The original system was called the Universal Video Disc Recorder System. The modified system will now be referred to as the Solid State Video Recording System. 5 figs.

Past experience in addressing the insider threat has led to the development of general principles for mitigating the insider threat while minimizing adverse impacts on site operations. Among the general principles developed was the requirement for real time tracking of personnel and material. A real time system for personnel and material tracking will aid in mitigating the insider threat by providing critical information regarding the movement and location of personnel and material. In addition, this system can provide an early detection mechanism for potential insider actions. This paper describes the development, operation, and performance of a technology-based system which utilizes radio frequency transmitters to achieve the real time tracking of personnel and material. The major elements of this system are personnel tracking credential which cannot be removed from an authorized individual without an alarm being sounded, and material control device which is utilized to control and monitor access to material. These elements form an insider protection system through the use of software which establishes the ''rules'' under which the system will operate. The performance of this system has been evaluated under both laboratory and operational settings in order to: (1) demonstrate the system's ability to successfully control access to material and areas by personnel, and (2) provide information regarding the status of materials in transit and storage. 3 refs., 1 fig.

The problem of determining the mechanical states inside wound capacitor rolls is addressed through the application of two dimensional, linear elasticity. Allowances are made for heterogeneous wound construction of the capacitor, orthotropic material behavior of the capacitor constituents, and arbitrary winding tension. A key element in the formulation is the derivation of material properties for a wound, orthotropic layer which is equivalent in behavior to a stack of dissimilar plies such as are actually wound on the capacitor simultaneously during one turn of the mandrel. The dissimilar plies are necessary by virtue of the conductor and dielectric materials which must be present in a capacitor. The derivation of predictive equations is based on winding the equivalent layer on an appropriate mandrel, followed by a recovery of the individual ply responses. The capability to explicitly calculate the winding tensions which would be necessary to produce a required wound tension dependence upon capacitor radius is also developed. Numerical results for typical capacitor design and construction are presented, and justification for the application of optimization theory in capacitor development is demonstrated. 4 refs., 5 figs.

The Nuclear Engineering Department of National Tsing Hua University organized a workshop on Severe Accident Management. The workshop was sponsored by Taiwan Power Company and was held at Taipei, Taiwan from July 31 to August 11, 1989. The topics covered in the workshop included the general in-vessel LWR severe accident phenomena, containment responses and performances under severe accident conditions, results of Level 1 PRAs of three Nuclear Power Plants at Taiwan, and also two lectures related to the NUREG-1150 report just published by US NRC. This presentation covers these two lectures.

Recent experiences in operating nuclear plants in the United States have demonstrated the need for an in situ cable condition monitoring technique that can assess whether installed, low-voltage, unshielded cables have local damage that could compromise their ability to function under normal and accident service conditions. This paper summarizes current US programs that have been initiated to develop a technological basis for monitoring cables with local degradation. 7 refs.

An axial flow turbine mass model has been developed and used to study axial flow turbines for space power systems. Hydrogen, helium-xenon, hydrogen-water vapor, air, and potassium vapor working fluids have been investigated to date. The impact of construction material, inlet temperature, rotational speed, pressure ratio, and power level on turbine mass and volume has been analyzed. This paper presents the turbine model description and results of parametric studies showing general design trends characteristic of any axial flow machine. Also, a comparison of axial flow turbine designs using helium-xenon mixtures and potassium vapor working fluids, which are used in Brayton and Rankine space power systems, respectively, is presented. 9 refs., 4 figs., 2 tabs.

Energetic fuel-coolant interactions may occur in a nuclear reactor in the event that molten fuel comes in contact with the reactor coolant water. Reliable mechanistic models of these interactions have yet to be developed and so relatively simple thermodynamic models have been proposed for estimating the conversion of thermal energy to mechanical work. The present paper outlines a generalized thermodynamic model for fuel-coolant interactions which accounts for variable thermodynamic properties as well as the effect of latent heat in the fuel. The variable property model is shown to provide an upper bound (most conservative) estimate of the conversion efficiency compared to other formulations appearing in the literature. 7 refs., 5 figs.

Unconfined heterogeneous two-phase detonations in liquid droplet-air mixtures are investigated. The liquid fuel is placed in a V-shaped channel and is dispersed into the atmosphere to form a cloud by an explosive detonating cord laid along the bottom vertex of the channel. An aerosol cloud 7 m high by about 1.5 m averaged width can be generated in this way with a typical mass ratio of fuel to explosive charge of 150. In the present study the length of channel used is typically 10 m giving a detonable fuel-air cloud of about 100 m/sup 3/. The propylene-oxide driver and the test fuel are disseminated simultaneously. Detonation in the propylene-oxide section is initiated by the sheet explosive and the detonation then transmits from this driver section into the rest of the cloud formed from the test fuel. For insensitive fuels requiring a larger cloud dimension, two parallel fuel troughs spaced 1.2 m apart are used. It is found that propylene-oxide and nitrated hydrocarbon fuels detonate quite readily. For the case of propylene-oxide, significant vaporization of the aerosol is observed prior to initiation so that detonation is essentially in the gas phase. 15 refs., 4 figs.

We find a strong correlation between the preirradiation 1/f noise of pMOS transistors and their radiation hardness. This suggests that current fluctuations may provide a useful, nondestructive probe of defects in MOS devices. 18 refs., 4 figs., 1 tab.

It is shown how standard ..delta..Vth and mobility measurements made on otherwise identical n- and p-channel transistors can be combined to accurately estimate radiation-induced ..delta..V/sub ot/ and ..delta..V/sub it/. Applications of the method are described. 12 refs., 2 figs.

Nuclear microprobe analysis (NMA) is a unique form of microbeam analysis in that it combines high lateral resolution with the high depth resolution techniques of conventional ion beam analysis (IBA) to nondestructively determine sample composition in three dimensions. By using depth sensitive IBA techniques (e.g., Rutherford Backscattering Spectrometry (RBS), Enhanced Backscattering Spectrometry (EBS) or Elastic Recoil Detection (ERD)), NMA finds its greatest utility in analyses requiring the following information: (1) 1--100 ppM sensitivity, (2) nondestructive three-dimensional depth profiling, and (3) quantitative light element analysis (e.g., the first two rows of the periodic table). This paper demonstrates the continuing evolution of NMA capabilities through two examples. First, the unique capabilities afforded NMA are shown in a simple yet accurate method to measure both oxygen and metal atom concentrations in Y-Ba-Cu-O alloys with micro-area ion beam analysis. Second, a NMA of buried tungsten lines in a silicon wafer demonstrates the complementary nature of information determined by NMA and scanning electron microscopy (SEM). 9 refs., 2 figs.

The ASSESS Neutralization Analysis module (Neutralization) is part of Analytic System and Software for Evaluation of Safeguards and Security, ASSESS, a vulnerability assessment tool. Neutralization models a fire fight engagement security inspectors (SIs) and adversaries. Results are based on probability of neutralization, P(N), which estimates the likelihood that SIs will win, given that SIs interrupt the attackers and begin an armed engagement. The calculating engine of the module is the Brief Adversary Threat Loss Estimator, BATLE. Engagements can have as many as thirty combatants on a side. Reinforcements may be introduced or combatant characteristics may be changed as many as ten times in one engagement. Inputs may be made with or without programmed guidance to the user. Combatant characteristics come from a modifiable library. Seven different characteristics can be independently specified for each combatant. Graphs of time distributions and studies of the sensitivity of P(N) to any combatant characteristic of either SIs or adversaries can be requested. Output files from Neutralization are used by Outsider Analysis to produce probability of security system win. 4 refs., 12 figs., 2 tabs.

The Facility Descriptor (Facility) module is part of the Analytic System and Software for Evaluating Safeguards and Security (ASSESS). Facility is the foundational software application in the ASSESS system for modelling a nuclear facility's safeguards and security system to determine the effectiveness against theft of special nuclear material. The Facility module provides the tools for an analyst to define a complete description of a facility's physical protection system which can then be used by other ASSESS software modules to determine vulnerability to a spectrum of insider and outsider threats. The analyst can enter a comprehensive description of the protection system layout including all secured areas, target locations, and detailed safeguards specifications. An extensive safeguard component catalog provides the reference data for calculating delay and detection performance. Multiple target locations within the same physical area may be specified, and the facility may be defined for two different operational states such as dayshift and nightshift. 6 refs., 5 figs.

Past experience in addressing the insider threat has led to the development of general principles for mitigating the insider threat while minimizing adverse impacts on site operations. Among the general principles developed was the requirement for real time tracking of personnel and material. A real time system for personnel and material tracking will aid in mitigating the insider threat by providing critical information regarding the movement and location of personnel and material. In addition, this system can provide an early detection mechanism for potential insider actions. This paper describes the development, operation, and performance of a technology-based system which utilizes radio frequency transmitters to achieve the real time tracking of personnel and material. The major elements of this system are a personnel tracking credential which cannot be removed from an authorized individual without an alarm being sounded, and a material control device which is utilized to control and monitor access to material. These elements form an insider protection system through the use of software which establishes the ''rules'' under which the system will operate. The performance of this system has been evaluated under both laboratory and operational settings in order to: (1) demonstrate the system's ability to successfully control access to material and areas by personnel, and (2) provide information regarding the status of materials in transit and storage. 3 refs., 1 fig.

Monte Carlo methods are used in a variety of applications such as risk assessment, probabilistic safety assessment, and reliability analysis. While Monte Carlo methods are simple to use, their application can be laborious. A new microcomputer software package has been developed that substantially reduces the effort requires to conduct Monte Carlo analyses. The Sensitivity and Uncertainty Analysis Shell (SUNS) is a software shell in the sense that a wide variety of application model can be incorporated into it. SUNS offers several useful features including a menu-driven environment, a flexible input editor, both Monte Carlo and Latin Hypercube sampling, the ability to perform both repeated trials and parametric studies in a single run, and both statistical and graphical output. SUNS also performs all required file management functions. 9 refs., 6 figs., 1 tab.

Inorganic thin films with molecular sieving properties have been formed by embedding microcrystals of zeolite Y and chabazite in a glassy silica matrix. The silica matrix was derived from sols prepared from tetraethylorthosilicate hydrolyzed under either acidic or basic conditions in alcoholic solution. Dip-coating, deposition of suspensions, or coating of zeolite dispersions with the glassy silica matrix were used to create the zeolite-silica films. The access of different probe molecules into the zeolitic part of the thin film was examined with in situ FTIR techniques and temperature-programmed-desorption studies. With all combinations of deposition techniques and silica matrices, the resulting films showed the molecular sieving properties of the parent zeolite. © 1989, Elsevier Science & Technology. All rights reserved.

Stand-off hypervelocity particle shields offer potential weight savings of an order of magnitude or more over conventional homogeneous armors. Based on an earlier complete model for the design and optimization of a stand-of shield system, a more restricted model appropriate for retrofit shields is described. Procedures to minimize the shield mass are provided, and scaling laws for many of the important parameter relationships are illustrated. 6 refs., 5 figs.