Energy Technology Data Exchange (ETDEWEB)

Abstract not provided

Energy Technology Data Exchange (ETDEWEB)

Ray tracing Monte Carlo calculations have been carried out using an existing Monte Carlo radiation transport code to obtain estimates of the microsave power exiting the torus coupling links in EPT microwave manifolds. The microwave power loss and polarization at surface reflections were accounted for by treating the microwaves as plane waves reflecting off plane surfaces. Agreement on the order of 10% was obtained between the measured and calculated output power distribution for an existing EBT-S toroidal manifold. A cost effective iterative procedure utilizing the Monte Carlo history data was implemented to predict design changes which could produce increased manifold efficiency and improved output power uniformity.

International Nuclear Information System (INIS)

Objective: To estimate exposure dose of personnel around patients by Monte Carlo method and integration method. Methods: Exposures were estimated by a Monte Carlo practical program with Visual Basic 6.0 and integration method using 'pen-and-paper'. Results: Exposures for rectangle and ellipse sources were calculated. The difference between different methods for various sources were 0.88% and 0.61%, respectively. Conclusion: The results estimated by Monte Carlo method are close to those of integration method. It is illustrated that doses of other people estimated by Monte Carlo method are significant

International Nuclear Information System (INIS)

Monte Carlo criticality calculations have been performed for over 50 years for reactor physics and criticality safety applications. With today's faster computers, these calculations are being carried out to greater precision (smaller uncertainties) in keff, and detailed distributions of power and reaction rates are being computed routinely. This paper provides a review of the fundamental theory of Monte Carlo criticality calculations, with guidance on practical methods for: (1) assuring convergence of both keff and the source distribution, (2) minimizing the bias in keff and reaction rate distributions, and (3) dealing with the under-prediction bias in uncertainties for keff and reaction rate distributions. (authors)

International Nuclear Information System (INIS)

Monte Carlo calculations performed to validate observed capture reaction rates of "1"2"9I and "2"3"7Np were in a reasonable agreement with experimental data obtained by the Joint Institute for Nuclear Research. The most significant discrepancy between the measurements and calculations (within a factor of 3) was observed for the NpO_2 sample and Pb target at 3.7 GeV proton energy

International Nuclear Information System (INIS)

We argue that the tachyons which exist in some string models are a signal of deconfinement. We compare the deconfinement temperature obtained from Monte Carlo calculations with some string models. (orig.).

International Nuclear Information System (INIS)

The Monte Carlo method is used to analyse the dose fall-off at the exit surface of a megavoltage photon beam. The convolution/superposition method of dose calculation using Monte-Carlo-generated homogeneous photon kernels is shown to be in error for exit dose calculation. Instead, photon kernels that incorporate modelling of the exit surface were generated, also using Monte Carlo, to analyse the problem, and the calculated dose fall-off using these kernels agrees well with measured data. In addition, the physics underlying the characteristics of the dose fall-off is analysed based on complete Monte Carlo modelling. Practical improvements to the convolution/superposition method are suggested. (Author).

Science.gov (United States)

In 2002 and again in 2003, an investigative journalist unit at ABC News transported a 6.8 kilogram metallic slug of depleted uranium (DU) via shipping container from Istanbul, Turkey to Brooklyn, NY and from Jakarta, Indonesia to Long Beach, CA. Targeted inspection of these shipping containers by Department of Homeland Security (DHS) personnel, included the use of gamma-ray imaging, portal monitors and hand-held radiation detectors, did not uncover the hidden DU. Monte Carlo analysis of the gamma-ray intensity and spectrum of a DU slug and one consisting of highly-enriched uranium (HEU) showed that DU was a proper surrogate for testing the ability of DHS to detect the illicit transport of HEU. Our analysis using MCNP-5 illustrated the ease of fully shielding an HEU sample to avoid detection. The assembly of an Improvised Nuclear Device (IND) -- a crude atomic bomb -- from sub-critical pieces of HEU metal was then examined via Monte Carlo ...

Energy Technology Data Exchange (ETDEWEB)

The Monte Carlo simulation method is applied to calculate the nucleon transfer part of the imaginary optical-model potential in colliding heavy ions. In the process of transfer of nucleons from one nucleus to the other, forward and backward neutrons and protons are treated separately by taking into consideration the effect of the Coulomb forces and the potential energy surfaces (driving forces). The Pauli exclusion principle is also incorporated properly in the calculation.

International Nuclear Information System (INIS)

A Monte Carlo method called transient curve fitting method was developed to calculate a eigenvalues by first simulating the existing neutrons and precursors in the system, then calculating the Eigen-distribution of neutron flux and calculating the a eigenvalues using the transient results based on the Eigen-distribution by the code TMCC. The results of this method are tested by calculating Godiva Benchmark problems and they agree well with the benchmark results. Then the reasonable results of Subcritical Facility in Tsinghua University are given by TMCC, and the results are compared with the experimental results measured by Rossi-a method. Even in the deep subcritical cases, the method can give results consistent with experimental results. (authors)

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A novel direct calculation method of response matrices on heterogeneous lattices by using the Monte Carlo method is proposed. These direct response matrices (DRMs) can be used in core calculations in place of the conventional homogenized lattice constants. The DRMs are formalized by four sub response matrices (sub-RMs) in order to respond to a core eigenvalue, k; thus the DRMs can be re-evaluated on each outer iteration in the core calculations. The sub-RMs can be evaluated by analyzing each neutron's trajectory from ordinary lattice calculations with the Monte Carlo code. Since these sub-RMs are calculated directly under an actual complex assembly geometry, i,e., without a homogenization process, intra-assembly heterogeneous effects can be reflected on global partial current balance calculations. With using two ...

International Nuclear Information System (INIS)

The global effect of activation cross-section uncertainties on calculated radiological quantities is investigated for the first time using a methodology based on Monte Carlo random sampling. The method is applied to the calculation of the uncertainty in the contact dose rate from the gunite shielding of the National Ignition Facility chamber after 30 yr of pulsed irradiation. Some critical cross section contributing significantly to the overall uncertainty are identified. By a reasonable reduction of the uncertainty in those cross sections, the accuracy in the calculated total contact dose rate is greatly improved.

British Library Electronic Table of Contents (United Kingdom)

During the last few decades, accuracy in photon and electron radiotherapy has increased substantially. This is partly due to enhanced linear accelerator technology, providing more flexibility in field definition (e.g. the usage of computer-controlled dynamic multileaf collimators), which led to intensity modulated radiotherapy (IMRT). Important improvements have also been made in the treatment planning process, more specifically in the dose calculations. Originally, dose calculations relied heavily on analytic, semi-analytic and empirical algorithms. The more accurate convolution/superposition codes use pre-calculated Monte Carlo dose "kernels" partly accounting for tissue density heterogeneities. It is generally recognized that the Monte Carlo method is able to increase accuracy even furt...

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The Feynmann and other fluctuation techniques have been shown to be useful for determining the multiplication of subcritical systems. The moments of the counting distribution from neutron detectors is analyzed to yield the multiplication value. We present the methodology and some selected applications and results and comparisons with Monte Carlo calculations.

International Nuclear Information System (INIS)

An ytterbium-169 high dose rate brachytherapy source, distinguished by an intensity-weighted average photon energy of 92.7 keV and a 32.015#+-#0.009 day half-life, is characterized in terms of the updated AAPM Task Group Report No. 43 specifications using the MCNP5 Monte Carlo computer code. In accordance with these specifications, the investigation included Monte Carlo simulations both in water and air with the in-air photon spectrum filtered to remove low-energy photons below 10 keV. TG-43 dosimetric data including S_K, D(r,#theta#), #LAMBDA#, g_L(r), F(r,#theta#), #phi#_a_n(r), and #phi#_a_n were calculated and statistical uncertainties in these parameters were derived and calculated in the appendix.

International Nuclear Information System (INIS)

The Monte Carlo transport codes LAHET and MCNP were used to calculate energy fluence spectra at three neutron therapy facilities. The results compare very favourably with measured data. Kerma spectra and the ratio of ICRU muscle tissue kerma to A-150 kerma, along the carbon to oxygen kerma ratio, were determined. Absorbed dose rate calculations are in reasonable agreement with measured values. Use of these codes to study modifications to existing therapy beams is briefly discussed. (author).

International Nuclear Information System (INIS)

The aim of this work was to compare dose calculation algorithm results at orthovoltage energies for a phantom composed of a bone slab in water. The calculation methods investigated were: no correction, ETAR, Batho, convolution/superposition and Monte Carlo. All algorithms calculated depth dose curves in a water phantom within 4% of experiment. However in the bone phantom, differences of over 40% between the No Correction / ETAR / Batho / Convolution and Monte Carlo results in the 1 cm thick bone slab were observed. These differences are predominantly because the algorithms do not account for the differing atomic number of the bone compared to water The increased dose to bone and the tissue adjacent to the bone interface should be considered when treating with orthovoltage photons. Copyright (1998) Australasian Physical and Engineering Sciences in Medicine

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A method, which estimates the lightning performance of high voltage transmission lines based on the Monte-Carlo simulation technique, is described in this paper. The average number of faults which occur in a transmission line, dividing them in single-phase and three-phase faults, as well as the average grounding resistances of the transmission lines are calculated. The method is applied, on several operating Greek transmission lines, showing good correlation between predicted and field observation results. The proposed method can be used as a useful tool in the design of electric power systems, aiding in the right insulation dimensioning of a transmission line.(author)

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A 2.45 MeV neutron time-of-flight spectrometer was designed and built for measurements of neutron energy spectra from the JT-60U Tokamak. The spectrometer consists of two fast plastic scintillators (50 cm{sup 2} and 1800 cm{sup 2}, thickness: 2 cm) where each detector is located on two constant time-of-flight spheres. The time-of-flight spheres have radius of 1 m which gives a neutron flight length of {approx}164 cm and a time-of-flight of {approx}92 ns for 2.45 MeV source neutrons. The calculated spectrometer efficiency and resolution are 2.8 x 10{sup -2} cm{sup 2} and 105 keV (4.3%), respectively. The energy resolution corresponds to a time resolution of 2.0 ns. The spectrometer will measure neutrons in a vertical line-of-sight, {approx}9 m from the plasma center. For a total neutron emission of 10{sup 16} n/s, the countrate in the first scattering detector, located in the neutron beam, is estimated to {approx}2.5 MHz. The useful countrate for this case is ...

International Nuclear Information System (INIS)

Tests for the applicability of a CFD (Computational Fluid Dynamics) code for simulating activity transport in PNA (Pulsed Neutron Activation) fluid measurements have been performed. The CFD code was combined with a Monte Carlo code used for the calculation of the initial activity distribution. The results from the calculations show that it is possible to use CFD for calculation of the activity distribution in PNA. The mainly qualitative results in this work are encouraging and suggest further work. In the continuation of this work a response function for the gamma detector will be calculated so that a PNA time spectrum can be simulated. A more accurate comparison with experimental data can then be performed

International Nuclear Information System (INIS)

The MCNPE-BO and MCNP4 Monte Carlo electron-photon codes were used to calculate the dose equivalent per unit fluence at various depths in tissue-equivalent slab phantoms for broad parallel beams of monoenergetic electrons with energies from 50 keV to 10 MeV. The study was carried out in the framework of the activities of a ICRP/ICRU Joint Task Group with the support of EURADOS WG4 (Numerical Dosimetry). Some preliminary results and comparisons as well as a general discussion on the performances of the codes are presented, demonstrating quite a satisfactory agreement among the results obtained using the two codes and those of other authors. (author).

Energy Technology Data Exchange (ETDEWEB)

Real time neutron radiography has been used to study the dynamic behavior of two phase flow and measure the time averaged vapor fraction in a heated metal tube containing boiling steam water operating at up to 15 bar pressure. The neutron radiographic technique is non-intrusive and requires no special transparent window region. This is the first time this technique has been used in an electrically heated pressurized flow loop. This unique experimental method offers the opportunity to observe and record on videotape, flow patterns and transient behavior of two phase flow inside opaque containers without disturbing the environment. In this study the test sections consisted of stainless steel tubes with a 1.27 cm outer diameter and wall thicknesses of 0.084 cm and 0.124 cm. The experiments were carried out at the Pennsylvania State University 1 megawatt TRIGA reactor facility utilizing a Precise Optics neutron radiography camera. The inlet water temperature to the ...

International Nuclear Information System (INIS)

Real time neutron radiography has been used to study the dynamic behavior of two phase flow and measure the time averaged vapor fraction in a heated metal tube containing boiling steam water operating at up to 15 bar pressure. The neutron radiographic technique is non-intrusive and requires no special transparent window region. This is the first time this technique has been used in an electrically heated pressurized flow loop. This unique experimental method offers the opportunity to observe and record on videotape, flow patterns and transient behavior of two phase flow inside opaque containers without disturbing the environment. In this study the test sections consisted of stainless steel tubes with a 1.27 cm outer diameter and wall thicknesses of 0.084 cm and 0.124 cm. The experiments were carried out at the Pennsylvania State University 1 megawatt TRIGA reactor facility utilizing a Precise Optics neutron radiography camera. The inlet water temperature to the ...

Energy Technology Data Exchange (ETDEWEB)

This paper reports on three-dimensional continuous-energy coupled neutron-gamma Monte Carlo models of the Advanced Neutron Source (ANS) final preconceptual and conceptual reference core designs developed using the Monte Carlo Neutron and Photon transport code (MCNP) Version 3b. These models contain the reactor core with control rods, the heavy water reflector tank with shutdown rods and some beam tubes, and the outer light water pool. Eighty homogenized fuel zones per fuel element are used to represent the radial and axial {sup 235}U fuel distribution. These models are the most sophisticated, physically accurate reactor physics models of the ANS currently available. The use of MCNP methods and applications to the ANS are demonstrated. Beam tube studies, coolant voiding studies, and many criticality studies have already been performed, as have studies with variance reduction techniques. In comparison with deterministic methods, MCNP proves ...

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Analyses of pressure vessel damage resulting from neutron irradiation have primarily relied on two-dimensional transport calculations and a spatial-synthesis methodology to accommodate three-dimensional effects in the results of two two-dimensional calculations. In this paper, the authors report on calculations made on the Pool Critical Assembly (PCA) Benchmark, Configuration 12/13, using the three-dimensional, continuous energy Monte Carlo transport code, MCNP, and the three-dimensional, multigroup, diffusion accelerated discrete ordinates transport code THREEDANT. Neutron fluxes and activation rates as determined from these two calculations are compared to each other and to experimental results in the literature. The authors also draw some conclusions on the value of 3D calculations on the interpretation of experimental results.

International Nuclear Information System (INIS)

Monte Carlo simulation of beam modifiers such as physical wedges and compensating filters has been performed with a rectilinear voxel geometry module. A modified version of the EGS4/DOSXYZ code has been developed for this purpose. The new implementations have been validated against the BEAM Monte Carlo code using its standard component modules (CMs) in several geometrical conditions. No significant disagreements were found within the statistical errors of 0.5% for photons and 2% for electrons. The clinical applicability and flexibility of the new version of the code has been assessed through an extensive verification versus dosimetric data. Both Varian multi-leaf collimator (MLC) wedges and standard wedges have been simulated and compared against experiments for 6 MV photon beams and different field sizes. Good agreement was found between calculated and measured depth doses and lateral dose profiles along both wedged and ...

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A microemulsion comprised of water, Brij 78, pentanol and styrene into which PPO and bis-MSB had been dissolved was prepared. Polymerization of the styrene resulted in a suspension of fluor-containing polystyrene nanoparticles (<100 nm). After a concentration step, the aqueous nanosuspension was able to detect {sup 14}C with counting efficiencies over 50% of those of a commercially available scintillation cocktail. Monte Carlo calculations demonstrated that the size and concentration of the nanoparticles were appropriate for optimum detection efficiency.

Energy Technology Data Exchange (ETDEWEB)

A model has been developed to predict the chemical composition of lakes that form in pyrite-bearing open-pit mines. Pyrite oxidation in wall rock releases sulfuric acid and metals, which mix with ground waters in the lake. Aqueous metal concentrations are calculated using MINTEQA2.

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This study presents results from Monte Carlo radiation transport calculations aimed at characterizing a novel methodology being developed to detect partial defects in Pressurized Water Reactor (PWR) spent fuel assemblies (SFAs). The methodology uses a combination of measured neutron and gamma fields inside a spent fuel assembly in an in-situ condition where no movement of the fuel assembly is required. Previous studies performed on single isolated assemblies resulted in a unique base signature that would change when some of the fuel in the assembly is replaced with dummy fuel. These studies indicate that this signature is still valid in the in-situ condition enhancing the prospect of building a practical tool, Partial Defect Detector (PDET), which can be used in the field for partial defect detection.

Science.gov (United States)

TART97 is a coupled neutron-photon, 3 dimensional, combinatorial geometry, time dependent Monte Carlo 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. TART97 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. TART 97 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. TART97 completely supersedes all older versions of TART, and it is strongly recommended that users only use the most recent version of TART97 and ist data files.

CERN Document Server

Monte Carlo calculations of proton irradiation of permanent magnets for the TRADE experiment have been performed. An irradiation dose of about 4´106 Gy/yr/mA has been estimated due to beam losses in normal operating conditions. Existing experimental results indicate that this irradiation level may induce a considerable demagnetization: in fact, a dose of 6´107 Gy induces a remanence loss of 0.3 % on samples of Sm2Co17 magnets, which are the most resistant type. More detailed calculations with the final design of the magnets and of the beam line are suggested, to determine if the irradiation levels allowed a reliable operation of the permanent magnets for the entire duration of the TRADE experiment. Damage and gas production rates have also been calculated; the values obtained are very low, thus confirming that the demagnetization process is in great part reversible.

International Nuclear Information System (INIS)

High-energy ionizing radiation is a prominent modality for the treatment of many cancers. The approaches to electron dose calculation can be categorized into semi-empirical models (e.g. Fermi-Eyges, convolution-superposition) and probabilistic methods (e.g. Monte Carlo). A third approach to dose calculation has only recently attracted attention in the medical physics community. This approach is based on the deterministic kinetic equations of radiative transfer. We derive a macroscopic partial differential equation model for electron transport in tissue. This model involves an angular closure in the phase space. It is exact for the free streaming and the isotropic regime. We solve it numerically by a newly developed HLLC scheme based on Berthon et al (2007 J. Sci. Comput. 31 347-89) that exactly preserves the key properties of the analytical solution on the discrete level. We discuss several test cases taken from the medical ...

CERN Document Server

Monte Carlo calculations using the codes PENELOPE and GEANT4 have been performed to characterize the dosimetric parameters of the new 20 mm long catheter based $^{32}$P beta source manufactured by Guidant Corporation. The dose distribution along the transverse axis and the two dimensional dose rate table have been calculated. Also, the dose rate at the reference point, the radial dose function and the anisotropy function were evaluated according to the adapted TG-60 formalism for cylindrical sources. PENELOPE and GEANT4 codes were first verified against previous results corresponding to the old 27 mm Guidant $^{32}$P beta source. The dose rate at the reference point for the unsheathed 27 mm source in water was calculated to be $0.215 \\pm 0.001$ cGy s$^{-1}$ mCi$^{-1}$, for PENELOPE, and $0.2312 \\pm 0.0008$ cGy s$^{-1}$ mCi$^{-1}$, for GEANT4. For the unsheathed 20 mm source these values were $0.2908 ...

International Nuclear Information System (INIS)

An important unresolved issue in outcomes analysis for lung complications is the effect of poor or completely lacking heterogeneity corrections in previously archived treatment plans. To estimate this effect, we developed a novel method based on Monte Carlo (MC) dose calculations which can be applied retrospectively to RTOG/AAPM-style archived treatment plans (ATP). We applied this method to 218 archived nonsmall cell lung cancer lung treatment plans that were originally calculated either without heterogeneity corrections or with primitive corrections. To retrospectively specify beam weights and wedges, beams were broken into Monte Carlo-generated beamlets, simulated using the VMC++ code, and mathematical optimization was used to match the archived water-based dose distributions. The derived beam weights (and any wedge effects) were then applied to Monte Carlo beamlets regenerated ...

International Nuclear Information System (INIS)

The Accelerator Transmutation Waste System is under development at the Los Alamos National Laboratory. The goal is to perform an independent verification of the feasibility of actinide and long-lived fission product burning in this system. The authors' work is divided into five tasks: (a) production of an actinide and long-lived fission product cross section library from JEF 2.2; (b) simulation using MCNP and KENO IV Monte Carlo codes, of the Accelerator Transmutation Waste System configurations existing in literature; (c) validation of HETC Monte Carlo code (production of spallation source); (d) validation of the cross sections by comparison of Keff and reaction rate results, calculated with MNCP and KENO IV, with experimental benchmarks and intercomparison between the authors' calculations of a PWR unit cell and the computations carried out with various codes and cross section libraries (NEACRP ...

CERN Document Server

Brachytherapy is a radiotherapeutic modality that makes use of radionuclides to deliver a high radiation dose to a well-defined volume while sparing surrounding healthy structures. At the National Institute for Cancer Research of Genova a High Dose Rate remote afterloading system provides Ir(192) endocavitary brachytherapy treatments. We studied the possibility to use the Geant4 Monte Carlo simulation toolkit in brachytherapy for calculation of complex physical parameters, not directly available by experiment al measurements, used in treatment planning dose deposition models.

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An accelerator experiment was performed using a low-energy antiproton beam to measure antiproton detection efficiency of BESS, a balloon-borne spectrometer with a superconducting solenoid. Measured efficiencies showed good agreement with calculated ones derived from the BESS Monte Carlo simulation based on GEANT/GHEISHA. With detailed verification of the BESS simulation, the relative systematic error of detection efficiency derived from the BESS simulation has been determined to be {+-}5%, compared with the previous estimation of {+-}15% which was the dominant uncertainty for measurements of cosmic-ray antiproton flux.

International Nuclear Information System (INIS)

The CyberKnife Robotic Radiosurgery System (Accuracy Incorporated, Sunnyvale, CA, USA) is used worldwide to treat tumors and neurological disorders anywhere in the body with sub-millimetre beam delivery accuracy. Accuracy has developed a number of new technologies in recent years to enhance the treatment of cancer patients. Such new technologies include a fast Monte Carlo Dose Calculation algorithm, Sequential Optimization dose planning, the IrisTM Variable Aperture Collimator, an 800 MU/min Linear Accelerator, and Optimized Path Traversal. These technologies enable physicists and physicians to plan treatments quickly and easily and deliver them with unrivalled accuracy and precision

Energy Technology Data Exchange (ETDEWEB)

An accelerator beam experiment was performed using a low-energy antiproton beam to measure antiproton detection efficiency of the BESS detector. Measured and calculated efficiencies derived from the BESS Monte Carlo simulation based on GRANT/GHEISHA showed good agreement. With detailed verification of the BESS simulation, the relative systematic error of detection efficiency derived from the BESS simulation has been determined to be {+-}5%, compared with the previous estimation of {+-}15% which was the dominant uncertainty for measurements of cosmic-ray antiproton flux. (author)

International Nuclear Information System (INIS)

Accurate modeling of system response and scatter distribution is crucial for image reconstruction in emission tomography. Monte Carlo simulations are very well suited to calculate these quantities. However, Monte Carlo simulations are also slow and many simulated counts are needed to provide a sufficiently exact estimate of the detection probabilities. In order to overcome these problems, we propose to split the simulation into two parts, the detection system and the object to be imaged (the patient). A so-called 'virtual boundary' that separates these two parts is introduced. Within the patient, particles are simulated conventionally. Whenever a photon reaches the virtual boundary, its detection probability is calculated analytically by evaluating a multi-dimensional B-spline that depends on the photon position, direction and energy. The unknown B-spline knot values that define this B-spline are fixed ...

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This report is composed of the following two parts and appendix. (I) Improvement of the Method for Evaluating Reactivity Based on Monte Carlo Perturbation Theory: Theoretical formulation in Monte Carlo perturbation method had been checked, and then introduced into a calculation code. There are some cases that the results of the change of eigenvalues becomes positive or negative by changing the estimator, and there is no reasonable difference in the results between the conventional method, which does not consider the change of neutron source distribution caused by a perturbation, and the new method, which consider that change. Thus it is still necessary to check the Monte Carlo perturbation code. (II) Improvement of Nodal Transport Method for 3-D Hexagonal Geometry: We can accurately evaluate hexagonal geometry FBR core by nodal transport calculation code for hexagonal-Z geometry ...

International Nuclear Information System (INIS)

The status of Monte Carlo system for the simulation of Bremsstrahlung in arbitrary decays and for the decay itself of #tau# -lepton is reviewed. During the last #tau# -lepton conference in 2010 several developments of the last two years have been presented: (i) For the TAUOLA Monte Carlo generator of #tau# -lepton decays, automated and simultaneous use of many versions of form-factors for the calculation of optional weights for fits was developed and checked to work in Belle and BaBar software environment. On-going work on alternative parameterizations of hadronic decays is presented too. (ii) The TAUOLA universal interface based on HepMC (the C++ event record) is now public. A similar interface for PHOTOS is now also public. (iii) Extension of PHOTOS Monte Carlo for QED Bremsstrahlung in decays featuring kernels based on complete first order matrix element are gradually becoming widely available thanks ...

International Nuclear Information System (INIS)

An extensive set of benchmark measurement of PDDs and beam profiles was performed in a heterogeneous layer phantom, including a lung equivalent heterogeneity, by means of several detectors and compared against the predicted dose values by different calculation algorithms in two treatment planning systems. PDDs were measured with TLDs, plane parallel and cylindrical ionization chambers and beam profiles with films. Additionally, Monte Carlo simulations by meansof the PENELOPE code were performed. Four different field sizes (10x10, 5x5, 2x2, and1x1 cm"2) and two lung equivalent materials (CIRS, #rho#_e"w=0.195 and St. Bartholomew Hospital, London, #rho#_e"w=0.244-0.322) were studied. The performance of four correction-based algorithms and one based on convolution-superposition was analyzed. The correction-based algorithms were the Batho, the Modified Batho, and the Equivalent TAR implemented in the Cadplan (Varian) treatment planning system and ...

International Nuclear Information System (INIS)

In the convolution/superposition method of photon beam dose calculations, inhomogeneities are usually handled by using some form of scaling involving the relative electron densities of the inhomogeneities. In this paper the accuracy of density scaling as applied to primary electrons generated in photon interactions is examined. Monte Carlo calculations are compared with density scaling calculations for air and cork slab inhomogeneities. For individual primary photon kernels as well as for photon interactions restricted to a thin layer, the results can differ significantly, by up to 50%, between the two calculations. However, for realistic photon beams where interactions occur throughout the whole irradiated volume, the discrepancies are much less severe. The discrepancies for the kernel calculation are attributed to the scattering characteristics of the ...

International Nuclear Information System (INIS)

While there have been many experimental and calculational investigations on absorbed dose distribution in the patient resulting from conventional X-ray procedures, such data for computerized tomography (CT) are still sparse. As this diagnostic procedure has shown a rapid increase in application during recent years, we have determined absorbed dose to body organs in a human phantom resulting from CT examinations. The exposure model consists of the heterogeneous MIRD-5 phantom and a suitable Monte-Carlo method to calculate absorbed dose to organs of interest. The exposure conditions are specified according to the exposure specifications of a CT-scanner currently in use. The calculations cover the range of body tissues of interest in terms of organ absorbed doses as well as a risk weighted absorbed dose. A detailed example showing the calculation of red bone marrow dose is given and a ...

International Nuclear Information System (INIS)

The basic relationships of the convolution/superposition dose calculation technique are reviewed, and a modelling technique that can be used for obtaining a satisfactory beam model for a commercially available convolution/superposition-based treatment planning system is described. A fluence energy spectrum for a Co-60 treatment machine obtained from a Monte Carlo simulation was used for modelling the fluence spectrum for a Rokus M machine. In order to achieve this model we measured the depth dose distribution and the dose profiles with a Wellhofer dosimetry system. The primary fluence was iteratively modelled by comparing the computed depth dose curves and beam profiles with the depth dose curves and crossbeam profiles measured in a water phantom. The objective of beam modelling is to build a model of the primary fluence that the patient is exposed to, which can then be used for the calculation of the dose deposited in the ...

International Nuclear Information System (INIS)

Using Monte Carlo simulation and the convolution/superposition algorithm, this work examines percent depth dose curves of the central axis in an acrylic phantom (20x20x20 cm"3) with variously sized air cavities (20x20x1.0, 20x20x2.0, 20x20x3.0, 20x20x4.0 and 20x20x4.95 cm"3 for study of longitudinal electron disequilibrium (ED) and 3.6x3.6x4.95, 4.5x4.5x4.95, 5.4x5.4x4.95 and 20x20x4.95 cm"3 for study of lateral ED). Radiochromic film samples are also measured to verify the Monte Carlo results. The Monte Carlo simulation is performed using OMEGA/BEAM and DOSXYZ codes, and the convolution/superposition calculation relies on an ADAC commercial treatment planning system. Underestimating the dose kernel expansion leads to overestimating the dose of what was found in the air cavity of ED using the convolution/superposition algorithm. Consequently, the dose in the rebuild-up region is influenced. The ...

International Nuclear Information System (INIS)

The convolution/superposition calculations for radiotherapy dose distributions are traditionally performed by convolving polyenergetic energy deposition kernels with TERMA (total energy released per unit mass) precomputed in each voxel of the irradiated phantom. We propose an alternative method in which the TERMA calculation is replaced by random sampling of photon energy, direction and interaction point. Then, a direction is randomly sampled from the angular distribution of the monoenergetic kernel corresponding to the photon energy. The kernel ray is propagated across the phantom, and energy is deposited in each voxel traversed. An important advantage of the explicit sampling of energy is that spectral changes with depth are automatically accounted for. No spectral or kernel hardening corrections are needed. Furthermore, the continuous sampling of photon direction allows us to model sharp changes in fluence, such as those due to collimator ...

International Nuclear Information System (INIS)

We investigate the effects of single-particle structure and pairing on the equilibration of positive and negative-parity level densities for the even-even nuclei "5"8","6"2","6"6Fe and "5"8Ni and the odd-A nuclei "5"9Ni and "6"5Fe. Calculations are performed using the shell model Monte Carlo method in the complete fp-gds shell-model space using a pairing+quadrupole type residual interaction. We find for the even-even nuclei that the positive-parity states dominate at low excitation energies due to strong pairing correlations. At excitation energies at which pairs are broken, single-particle structure of these nuclei is seen to play the decisive role for the energy dependence of the ratio of negative-to-positive parity level densities. We also find that equilibration energies are noticeably lower for the odd-A nuclei "5"9Ni and "6"5Fe than for the neighboring even-even nuclei "5"8Ni and "6"6Fe.

International Nuclear Information System (INIS)

Employing a recently developed Monte-Carlo model, we study the fission of 240Pu induced by neutrons with energies from thermal to just below the threshold for second chance fission. Current measurements of the mean number of prompt neutrons emitted in fission, together with less accurate measurements of the neutron energy spectra, place remarkably fine constraints on predictions of microscopic calculations. In particular, the total excitation energy of the nascent fragments must be specified to within 1MeV to avoid disagreement with measurements of the mean neutron multiplicity. The combination of the Monte-Carlo fission model with a statistical likelihood analysis also presents a powerful tool for the evaluation of fission neutron data. Of particular importance is the fission spectrum, which plays a key role in determining reactor criticality. We show that our approach can be used to develop an estimate of the fission ...

Energy Technology Data Exchange (ETDEWEB)

This thesis consists of five chapters, each of which is a self-contained unit. The first chapter overviews methods for electronic-structure calculations. Chapter 2 introduces a new method to generate a rapidly converging configuration expansion. The approach iteratively combines (1) a least-squares fitting of a configuration expansion to a many-body wave function with (2) a transfer-matrix method for projecting out the ground state. Results are shown to be equivalent to multiconfiguration Hartree-Fock. Results from test calculations are given for a simple finite difference model of the helium atom. In Chapter 3 the use of the finite-element method in electronic structure calculations is discussed. Chapters 4 and 5 discuss developments in Monte Carlo methods based on Hubbard-Stratonovich transformations. Chapter 4 introduces a canonical ensemble formulation of the method, which is more appropriate than ...

British Library Electronic Table of Contents (United Kingdom)

The principal objective of this study is to formulate an effective optimal fuel management strategy for the TRIGA MARK II research reactor at AERE, Savar. The core management study has been performed by utilizing four basic types of information calculated for the reactor: criticality, power peaking, neutron flux and burnup calculation. This paper presents the results of the burnup calculations for TRIGA LEU fuel elements. The fuel element burnup for approximately 20 years of operation was calculated using the TRIGAP compute code. The calculation is performed in one-dimensional radial geometry in TRIGAP. Inter-comparison of TRIGAP results with other two calculations performed by MVP-BURN and MCNP4C-ORIGEN2.1 show very good agreement. Reshuffling at 20,000MWh step provides the highest core l...

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The GASPAR module utilized in MAXIGASP and POPGASP has been verified by hand calculations. The program operates as documented by the NRC [Eckerman et. al. 1980]. Equations used in the code to calculate downwind deposition rates, concentrations in air, on ground surfaces, and in vegetables, meat, and milk are provided in this report.

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Experiments with fresh PWR fuel assemblies were performed to assess the {sup 252}Cf-source-driven frequency analysis method for measuring the subcriticality of spent fuel. The measurements at the Babcox and Wilcox Critical Experiments Facility mocked up between 17x17 fuel pins (single assembly) and a full array of 4961 fuel pins (about 17 fuel assemblies) in borated water with a fixed B concentration. For the full array, the B content of the water was varied from 1511 at delayed criticality to 4303 ppM. Measurements were done for various source-detector-fuel pin configurations; they showed high sensitivity of frequency analysis parameters to B content and fissile mass. Parameters such as auto and cross power spectral densities can be calculated directly by a more general model of the Monte Carlo code (MCNP-DSP). Calculation-measurement comparisons are presented. This model permits the validation of neutron and gamma ray ...

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Purpose: calculation of conversion coefficients for the reconstruction of organ doses from entrance doses for abdomen radiographs of 0, 1, 5, 10, 15, and 30-year-old patients in conventional pediatric radiology for the radiographic settings recommended by the German and European guidelines for quality management in diagnostic radiology. Materials und method: using the commercially available personal computer program PCXMC developed by the Finnish Center for Radiation and Nuclear Safety (Saeteilyturvakeskus STUK), conversion coefficients for conventional abdomen radiographs were calculated performing Monte Carlo simulations in mathematical hermaphrodite phantom models describing patients of different ages. The possible clinical variation of beam collimation was taken into consideration by defining optimal and suboptimal radiation fields on the phantoms' surfaces. Results: conversion coefficients for the ...

International Nuclear Information System (INIS)

The calculation of electronn beam dose using an algorithms similar to convolution/superposition methods for photon beams [1,2,3,4] is explored. The distribution of dose deposited by a number of monoenergetic, point-monodirectional electron pencil beams is first determined using the Monte Carlo method [5,6]. These elementary distributions are combined to model distributions that would result from the spectrum of incident energies and angles [6,7] present in a clinical beam. These modified distributions are then stored for use as kernels in the dose calculation. In the case of a homogeneous phantom, the relative fluence distribution is convolved with the stored kernels to obtain thhe dose distributions in 3 dimensions. Since the kernels cannot be assumed to be spatially invariant in a heterogeneous water-like phantom, the dose deposited on paths from the interaction site to all the dose deposition sites is approximated by ...

Energy Technology Data Exchange (ETDEWEB)

We present results from a kinetic Monte Carlo simulation of boron transient enhanced diffusion (TED) in silicon. Our approach avoids the use of phenomenological fits to experimental data by using a complete and self-consistent set of values for defect and dopant energetics derived mostly from {ital ab initio} calculations. The results predict that, during annealing of 40 keV B-implanted Si at 800{degree}C, there exists a time window during which all the implanted boron atoms are substitutional. At earlier or later times, the interactions between free silicon self-interstitials and boron atoms drive the growth of boron clusters and result in an inactive boron fraction. The results show that the majority of boron TED takes place during the growth period of interstitial clusters and not during their dissolution. {copyright} {ital 1998 American Institute of Physics.}

British Library Electronic Table of Contents (United Kingdom)

The effects of pore curvature and surface heterogeneity on the adsorption of water on a graphitic surface at 298 K were investigated using a Grand Canonical Monte Carlo (GCMC) simulation. Slit and cylindrical pores are used to study the curvature effects. To investigate the surface heterogeneity the functional group and the structural defect on the surface were specifically considered. The hydroxyl group (OH) is used as a model for the functional group and the water potential model proposed by Muller et al. is used to calculate the water interaction. For the homogeneous cylinder, the pore filling occurs at a pressure lower than the saturation pressure of the water model, while it is greater in the case of homogeneous slit pore. The size of hysteresis loop is more sensitive to the length of...

International Nuclear Information System (INIS)

New values of the factors required to convert the reading of a radiation dosemeter calibrated in terms of air kerma (or exposure) into absorbed dose to water for medium-energy x-radiation were given in a code of practice published by the International Atomic Energy Agency in 1987. These are not considered to possess sufficient support from other sources. It is therefore recommended that the F-factors given or codes of practice should continue to be used. Values of backscatter factors for low-energy x-radiation (below 140 kV) in Supplement 17 of the British Journal of Radiology appear to be inaccurate. New values based on Monte Carlo calculations, and supported by new experimental data, are given for use in radiotherapy. (author).

British Library Electronic Table of Contents (United Kingdom)

An energy transfer and conversion model for high-temperature solar cavity receivers has been developed using the transport behaviour of solar radiation as described by the spectral radiative exchange factors. A Monte-Carlo ray-tracing method coupled with optical properties was adopted, to predict radiation characteristics of the solar collector system by calculating radiative exchange factors. A cavity receiver with a plano-convexo quartz window was proposed, based upon the directional characteristics of the focal flux and the redistribution effect of the quartz window. Parametric studies on the windowed receiver provided a more uniform flux distribution, higher efficiency and lower loss than the windowless receivers. The predicted results serve as a design reference for the solar receiver...

International Nuclear Information System (INIS)

The present work summarizes efforts on the simulation of natural convection cooling within the IFMIF target and test cell. The simulations have been performed with the STAR-CD code using the k-#omega# high-Reynolds number turbulence model. A dedicated thermohydraulic model has been devised including Lithium loop components. Nuclear heat production has been calculated by the Monte-Carlo code McDeLicious for different parts of the target and test cell walls and was used as input for the STAR-CD simulations. Helium atmospheres at several pressures from 0.1 to 10"-"5 MPa have been investigated. In order to limit the maximum temperature of the concrete walls to 80 deg. C it was necessary to add thermal insulation layers to the hot Lithium loop surfaces and a conceptual system of two cooling layers in different depths of the concrete walls.

Energy Technology Data Exchange (ETDEWEB)

Incomplete convergence in numerical simulation such as computational physics simulations and/or Monte Carlo simulations can enter into the calculation of the objective function in an optimization problem, producing noise, bias, and topo- graphical inaccuracy in the objective function. These affect accuracy and convergence rate in the optimization problem. This paper is concerned with global searching of a diverse parameter space, graduating to accelerated local convergence to a (hopefully) global optimum, in a framework that acknowledges convergence uncertainty and manages model resolu- tion to efficiently reduce uncertainty in the final optimum. In its own right, the global-to-local optimization engine employed here (devised for noise tolerance) performs better than other classical and contemporary optimization approaches tried individually and in combination on the "industrial" test problem to be presented.

CERN Document Server

We investigate the behavior of a circuit QED device when the resonator is initially populated with a mesoscopic coherent field. The strong coupling between the cavity and the qubit produces an entangled state involving mesoscopic quasi-pointer states with respect to cavity dissipation. The overlap of the associated field components results in collapse and revivals for the Rabi oscillation. Although qubit relaxation and dephasing do not preserve these states, a simple analytical description of the dissipative dynamics of the circuit QED device including cavity relaxation as well as qubit dissipation is obtained from the Monte-Carlo approach. Explicit predictions for the spontaneous and induced Rabi oscillation signals are derived and sucessfully compared with exact calculations. We show that these interesting effects could be observed with a 10 photon field in forthcoming circuit QED experiments.

International Nuclear Information System (INIS)

We present results of multiple-time-scale simulations of 5, 10 and 15 keV low temperature ion implantation of arsenic on silicon (100), followed by high temperature anneals. The simulations start with a molecular dynamics (MD) calculation of the primary state of damage after 10ps. The results are then coupled to a kinetic Monte Carlo (MC) simulation of bulk defect diffusion and clustering. Dose accumulation is achieved considering that at low temperatures the damage produced in the lattice is stable. After the desired dose is accumulated, the system is annealed at 800 degrees C for several seconds. The results provide information on the evolution for the damage microstructure over macroscopic length and time scales and affords direct comparison to experimental results. We discuss the database of inputs to the MC model and how it affects the diffusion process.

British Library Electronic Table of Contents (United Kingdom)

We carried out theoretical analyses based on ab initio calculations that incorporate free energy of the vapor phase in order to determine the initial growth process of cubic GaN on GaN (001)-(4x1). The results suggest that a N-adsorbed structure appears at the initial growth stage and then Ga adsorbs on the N-adsorbed GaN (001)-(4x1) surface. Considering this process, we performed Monte Carlo simulations. The results suggest that the maximum point of Ga coverage after supplying a Formula Not Shown monolayer of atoms shifted toward a Ga-rich condition from V/III=1.0.

Energy Technology Data Exchange (ETDEWEB)

A classical model is presented for magnetic field-induced Wigner crystallization in electron systems confined within two-dimensional quantum dots. In contrast to other classical models, this one does not treat an electron as a point charge; the electron density is assumed to take a Gaussian form corresponding to the lowest Landau level. Using a Monte Carlo method we have determined the equilibrium configurations as functions of the magnetic field. We have found a classical counterpart of the quantum maximum density droplet (MDD) and studied the breakdown of the MDD into a Wigner molecule as well as the transformations of the Wigner molecule shape induced by the external magnetic field. The phase diagram for the classical Wigner molecules has been presented and its qualitative agreement with previous quantum mechanical calculations has been shown.

Science.gov (United States)

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International Nuclear Information System (INIS)

The goal of this work is to present a systematic Monte Carlo validation study on the clinical implementation of the enhanced dynamic wedges (EDWs) into the Pinnacle"3 (Philips Medical Systems, Fitchburg, WI) treatment planning system (TPS) and QA procedures for patient plan verification treated with EDWs. Modeling of EDW beams in the Pinnacle"3 TPS, which employs a collapsed-cone convolution superposition (CCCS) dose model, was based on a combination of measured open-beam data and the 'Golden Segmented Treatment Table' (GSTT) provided by Varian for each photon beam energy. To validate EDW models, dose profiles of 6 and 10 MV photon beams from a Clinac 2100 C/D were measured in virtual water at depths from near-surface to 30 cm for a wide range of field sizes and wedge angles using the Profiler 2 (Sun Nuclear Corporation, Melbourne, FL) diode array system. The EDW output factors (EDWOFs) for square fields from 4 to 20 cm wide were measured in virtual water using a ...

International Nuclear Information System (INIS)

The Anisotropic Analytical Algorithm (AAA) is a new pencil beam convolution/superposition algorithm proposed by Varian for photon dose calculations. The configuration of AAA depends on linear accelerator design and specifications. The purpose of this study was to investigate the accuracy of AAA for an Elekta SL25 linear accelerator for small fields and intensity modulated radiation therapy (IMRT) treatments in inhomogeneous media. The accuracy of AAA was evaluated in two studies. First, AAA was compared both with Monte Carlo (MC) and the measurements in an inhomogeneous phantom simulating lung equivalent tissues and bone ribs. The algorithm was tested under lateral electronic disequilibrium conditions, using small fields (2x2 cm"2). Good agreement was generally achieved for depth dose and profiles, with deviations generally below 3% in lung inhomogeneities and below 5% at interfaces. However, the effects of attenuation and scattering close to ...

British Library Electronic Table of Contents (United Kingdom)

Effective integration of nonproliferation management into the design process is key to the broad deployment of advanced nuclear energy systems, and is an explicit goal of the Laser Inertial Fusion Energy (LIFE) project at Lawrence Livermore National Laboratory. The nuclear explosives utility of a nuclear material to a state (proliferator) or sub-state (terrorist) is a critical factor to be assessed and is one aspect of material attractiveness. In this work, we approached nuclear explosives utility through the calculation of a ''figure of merit'' (FOM) that has recently been developed to capture the relative viability and difficulty of constructing nuclear explosives starting from various nuclear material forms and compositions. We discuss the integration of the figure of merit into an asse...

International Nuclear Information System (INIS)

Critical experiments have been analyzed to verify a nuclear analysis system for fast reactors used in Japan Nuclear Cycle Development Institute (JNC). The experiments were performed in a collaboration work between JNC and the Institute of Physics and Power Engineering of Russia to dispose Russian surplus weapons plutonium, focusing on the effect of the introduction of uranium-plutonium mixed-dioxide (MOX) fuel and stainless steel reflector into the current BN-600 core that is comprised of UO_2 fuel and blanket. The analysis results agreed well with measured values on most of the nuclear characteristics. The accuracies are comparable to those obtained for the conventional MOX fueled fast reactors. It suggests that the JNC analysis system can analyze accurately nuclear characteristics in uranium fueled cores as well. A significant improvement was achieved on the sodium void reactivity by employing an ultra fine group cell calculation system. A change in adjoint ...

Energy Technology Data Exchange (ETDEWEB)

The sub-criticality monitoring system has been developed for criticality safety control in nuclear fuel handling plants. In the past experiments performed with the Deuterium Critical Assembly (DCA), it was confirmed that the detection of sub-criticality was possible to k{sub eff} = 0.3. To investigate the applicability of the method to more generalized system, experiments were performed in the light-water-moderated system of the modified DCA core. From these experiments, it was confirmed that the prompt decay constant ({alpha}), which was a index of the sub-criticality, was detected between k{sub eff} = 0.623 and k{sub eff} = 0.870 and the difference of 0.05 - 0.1{Delta}k could be distinguished. The {alpha} values were numerically calculated with 2D transport code TWODANT and monte carlo code KENO V.a, and the results were compared with the measured values. The differences between calculated and measured values were proved ...

International Nuclear Information System (INIS)

Advanced modality of high-precision radiotherapy fulfilled by a composition of large numbers of small field beams called 'beamlets' can be achieved via nonuniform intensity fluencies. In case of radiation measurements and calculations with narrow high-energy photon beams, however, an accurate two-dimensional dosimetry is a challenging task due to dosimetrically unfavorable phenomena such as dramatic changes of the dose at the field boundaries, dis-equilibrium of the electrons resulting from larger detector volume, and non-uniformity between the detector and the phantom materials. Meanwhile, with the advantages of high spatial resolution and wide range of absorbed doses, there is a growing demand of GAFCHROMICat..EBT film to confirm delivered dose distribution. Especially, the effects from the material differences between the phantom and the film can be minimized in the heterogeneous condition since the GAFCHROMICat..EBT film is composed of tissueequivalent ...

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A calculation is presented of spontaneous radiation emitted by an electron beam passing through a continuously rotating quadrupole magnetic undulator. It is shown that radiation spectrum emitted in forward direction of beam propagation has four peaks, corresponding to four betatron frequencies. Utilizing the Madey theorem, a stimulated emission is calculated and presented as gain versus frequency curves, for different values of the quadrupole magnetic field. A free-electron laser operating at two or three radiation frequencies with a quadrupole magnetic wiggler is suggested.

Science.gov (United States)

Cancer is a severe threat to human health. Early detection is considered the best way to increase the chance for survival. While the traditional cancer detection method, biopsy, is invasive, noninvasive optical diagnostic techniques are revolutionizing the way that cancer is diagnosed. Reflectance spectroscopy is one of these optical spectroscopy techniques showing promise as a diagnostic tool for pre-cancer detection. When a neoplasia occurs in tissue, morphologic and biochemical changes happen in the tissue, which in turn results in the change of optical properties and reflectance spectroscopy. Therefore, a pre-cancer can be detected by extracting optical properties from reflectance spectroscopy. This dissertation described the construction of a fiberoptic based reflectance system and the development of a series of modeling studies. This research is aimed at establishing an improved understanding of the optical properties of mucosal tissues by analyzing reflectance signals at ...

Energy Technology Data Exchange (ETDEWEB)

Analysis of the coke gas combustion porcess is presented. Standard kinetic relationships were utilized. Calculations were performed for coke gas with high and low content of H/sub 2/ and for blasting air 20 and 100/sup 0/C. Temperature relationships, composition of gas combustion products and release of nitrogen oxides were determined. Results are analyzed which will make it possible to control the composition of combustion products.

International Nuclear Information System (INIS)

We study the dynamical evolution of globular clusters containing primordial binaries, including full single and binary stellar evolution using our Monte Carlo cluster evolution code updated with an adaptation of the single and binary stellar evolution codes SSE and BSE from Hurley et al. We describe the modifications that we have made to the code. We present several test calculations and comparisons with existing studies to illustrate the validity of the code. We show that our code finds very good agreement with direct N-body simulations including primordial binaries and stellar evolution. We find significant differences in the evolution of the global properties of the simulated clusters using stellar evolution compared with simulations without any stellar evolution. In particular, we find that the mass loss from the stellar evolution acts as a significant energy production channel simply by reducing the total gravitational binding energy and ...

British Library Electronic Table of Contents (United Kingdom)

We present structure calculations of neutral and singly ionized Mg clusters of up to 30 atoms, as well as Na clusters of up to 10 atoms. The calculations have been performed using density functional theory (DFT) within the local (spin-)density approximation, ion cores are described by pseudopotentials. We have utilized a new algorithm for solving the Kohn-Sham equations that is formulated entirely in coordinate space and, thus, permits straightforward control of the spatial resolution. Our numerical method is particularly suitable for modern parallel computer architectures; we have thus been able to combine an unrestricted simulated annealing procedure with electronic structure calculations of high spatial resolution, corresponding to a plane-wave cutoff of 954 eV for Mg. We report the geo...

International Nuclear Information System (INIS)

The electronic structures of BaSnO_3, BaSbO_3, and BaPbO_3, calculated using an extended general-potential linearized augmented-plane-wave method, are reported. The electronic structures of BaSnO_3 and its 6s analog BaPbO_3 are found to be very different, explaining the absence of superconductivity in the Ba(Sn,Sb)O_3 system. These differences are explained by a combination of the relativistic lowering of the 6s states and ion-size effects. Muffin-tin-approximation augmented-plane-wave calculations for BaSnO_3 are also reported and the utility of the muffin-tin approximation for this and similar materials is discussed in terms of the differences between the two sets of calculations.

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A thermal analysis of the Omnium-G receiver is presented and the technique is shown to be generally applicable to solar thermal receivers utilizing a directly heated thermal mass. The thermal loss coefficient, including reradiation losses, is calculated and shown to agree quite well with the experimentally measured thermal loss coefficient. The rate of heat transfer to the working fluid is also analyzed and the analysis is used to show that the Omnium-G receiver is well matched to the water/steam working fluid because the steam outlet temperature is almost the same as the receiver temperature. A general procedure for calculating receiver performance is presented. With this procedure, the energy delivery to any working fluid, the delivered temperature of the working fluid, and the pressure drop through the receiver can be determined. An example of the calculation is also presented.

Energy Technology Data Exchange (ETDEWEB)

The mass generation in the Standard Model of Particles Physics relies on a spontaneous symmetry breaking mechanism. Its implementation is recalled, along with its constraints, both theoretical (Naturalness, Stability, Triviality, Unitarity) and experimental (limits of direct and indirect searches, prospects). Calculation techniques for observables evaluation in Perturbative Field Theory are described, particularly Helicity Amplitude method, which is given in details: fermions and vector bosons, massless and massive. Monte-Carlo integration, and structure functions approximations (which allows non-perturbative calculations) are also detailed. With these tools, a process giving to Physics beyond the Standard Model is studied: it leads to an experimental prediction for the LEP collision ring, taking the classical background into account. Technical aspects of a future photon linear collider are reviewed. The production of heavy ...

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The calibration of cylindrical detectors using different types of radioactive sources is a matter of routine. The most accurate method, that of experiment, is limited by several factors when the energy interval is broad, requiring a relatively large number of primary standards, implying considerable investment of money and time. Several other techniques can be used instead, including Monte Carlo simulations and semi-empirical methods. Calculations based on the first technique require good definition of the geometry and materials, including the dead layer and window thickness together with an accurate set of cross-sections. The second technique requires two different types of experimental input, the first being from use of sources emitting cascade {gamma} rays and the second from use of sources emitting isolated {gamma} rays in order to cover the wide energy range and provide coincidence-summing corrections, respectively. Here, we introduce a ...

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The results of this study show that Monte Carlo simulations of diffusion in homogeneous turbulence can be formulated in terms of the Eulerian space-time velocity autocorrelation function. Numerical results obtained using this approach agree with results obtained by Taylor (1921) using the Lagrangian autocorrelation function. Use was made of the equivalence of the Lagrangian and Eulerian Monte Carlo approaches to derive analytic relations between the Lagrangian integral time scale and the Eulerian integral space and time scales. These analytic results were verified by comparison to Monte Carlo simulations and to other theoretical results. They are in general agreement with many existing theories and semi-empirical relations.

Energy Technology Data Exchange (ETDEWEB)

This paper is concerned with the validation of the 3D deterministic neutral-particle transport theory code EVENT for shielding applications. The code is based on the finite element-spherical harmonics (FE-P{sub N}) method which has been extensively developed over the last decade. A general multi-group, anisotropic scattering formalism enables the code to address realistic steady state and time dependent, multi-dimensional coupled neutron/gamma radiation transport problems involving high scattering and deep penetration alike. The powerful geometrical flexibility and competitive computational effort makes the code an attractive tool for shielding applications. In recognition of this, EVENT is currently in the process of being adopted by the UK nuclear industry. The theory behind EVENT is described and its numerical implementation is outlined. Numerical results obtained by the code are compared with predictions of the Monte Carlo code MCBEND and also with the results ...

Science.gov (United States)

In March 2007 in-pile testing of LEU U-Mo full-size IRT type fuel elements was started in the MIR reactor. Four prototype fuel elements for Uzbekistan WWR SM reactor are being tested simultaneously - two of tube type design and two of pin type design. The dismountable irradiation devices were constructed for intermediate reloading and inspection of fuel elements during reactor testing. The objective of the test is to obtain the experimental results for determination of more reliable design and licensing fuel elements for conversion of the WWR SM reactor. The heat power of fuel elements is measured on-line by thermal balance method. The distribution of fission density and burn-up of uranium in the volume of elements are calculated by using the MIR reactor MCU code (Monte-Carlo) model. In this paper the design of fuel elements, the technique, main parameters and preliminary results are described. (author)

CERN Document Server

We have performed multicanonical Monte Carlo simulations of C-peptide of ribonuclease A. It is known by CD and NMR experiments that this peptide has high alpha-helix content in aqueous solution and that the side-chain charges of residues Glu-2$^-$ and His-12$^+$ play an important role in the stability of the alpha-helix. In order to confirm these experimental implications, we have used two analogues of the peptide with charged and neutral side chains of Glu-2 and His-12. Two dielectric functions, distance-dependent and constant, are considered to study the effects of solvent contributions. All the simulations were started from random initial conformations. Various thermodynamic quantities such as average helicity as a function of residue number and average distance between two side chains as a function of temperature are calculated. The results are found to be in accord with the implications of CD and NMR experiments. The lowest-energy ...

CERN Document Server

For purposes of designing targeted cataclysmic variable (CV) detection surveys and interpreting results of other projects with many CV detections such as the ChaMPlane Survey, we have created a model of the CV distribution in the Galaxy. It is modeled as a warped, flared exponential disk with a gaussian vertical distribution. Extinction is based on a detailed Galactic dust and gas model. A luminosity function for CVs is also incorporated, based on a smoothed version of published data. We calculate predicted field detection rates as a function of the limiting magnitude expected for the detecting system (i.e. WIYN/Hydra or NOAO 4m/Mosaic). Monte-Carlo techniques are used to assess statistical fluctuations in these rates. We have created maps of the expected CV distribution for the full non-bulge Galactic plane (20

Energy Technology Data Exchange (ETDEWEB)

The O({alpha}) electroweak radiative corrections to {gamma}{gamma}{yields}WW{yields}4f within the electroweak standard model are calculated in double-pole approximation (DPA). Virtual corrections are treated in DPA, leading to a classification into factorizable and non-factorizable contributions, and real-photonic corrections are based on complete lowest-order matrix elements for {gamma}{gamma}{yields}4f+{gamma}. Soft and collinear singularities appearing in the virtual and real corrections are combined alternatively in two different ways, namely by using the dipole subtraction method or by applying phase-space slicing. The radiative corrections are implemented in a Monte Carlo generator called Coffer {gamma}{gamma} - the computer code can be obtained from the authors upon request - which optionally includes anomalous triple and quartic gauge-boson couplings in addition and performs a convolution over realistic spectra of the photon beams. A ...

Energy Technology Data Exchange (ETDEWEB)

This paper deals with electron flux densities and electron energy flux densities in positive column discharges. Recent kinetic calculations by Uhrlandt and Winkler have revealed the interesting physical phenomenon of radially inward directed energy flux densities in positive column plasmas. We have used a self-consistent positive column model, based on an accurate and highly detailed Monte Carlo code, to study this effect in more depth. The results of this study show a rather complex physical picture of electron particle and energy flux densities. Electrons with low energies usually exhibit radially outward directed particle and energy flux densities. At energies above the threshold for electronic excitation particle and energy flux densities are usually inward directed. Only close to the wall, at total energies above the wall potential energy, do these flux densities point towards the wall. The thickness of this 'wall loss ...

Energy Technology Data Exchange (ETDEWEB)

In electron beam therapy, tissue overdose due to electrons backscattered from lead has been profusely studied. To quantify this dose enhancement effect, an electron backscatter factor (EBF) wasdefined as the ratio of dose at the tissue-inhomogeneity interface with and without the scatterer present. The dependence of the EBF on energy at the scatterer surface is not well known for energies lower than 3 MeV which is the most frequent clinical situation. In this work, we have done Monte Carlo calculations with the GEANT code to study EBF in lead at this energy range. The applicability of this code and the developed procedure for dose estimation has been experimentally verified. The dependence of the EBF on the beam energy incident on the scatterer has been studied for different nominal beam energies incident at the phantom's surface. The results show a trend of increase of EBF with the beam energy incident on the scatterer between 0.5 and ...

Energy Technology Data Exchange (ETDEWEB)

A new atomistic approach to Si device process simulation is presented. It is based on a Monte Carlo diffusion code coupled to a binary collision program. Besides diffusion, the simulation includes recombination of vacancies and interstitials, clustering and re-emission from the clusters, and trapping of interstitials. We discuss the simulation of a typical room-temperature implant at 40 keV, 5{times}10{sup 13} cm{sup {minus}2} Si into (001)Si, followed by a high temperature (815{degree}C) anneal. The damage evolves into an excess of interstitials in the form of extended defects and with a total number close to the implanted dose. This result explains the success of the {open_quote}{open_quote}+1{close_quote}{close_quote} model, used to simulate transient diffusion of dopants after ion implantation. It is also in agreement with recent transmission electron microscopy observations of the number of interstitials stored in (311) defects. {copyright} {ital 1996 American ...

Science.gov (United States)

We report here a new approach to introduce the effect of chemisorption in the Monte-Carlo simulation procedure for studying the segregation behaviour in bimetallic nanoparticles at low pressures. A coordination-dependent pair interaction energy is constructed in terms of partial bond energies and the exchange energy where the partial bond energy can be empirically calculated from the experimental values of dimer energy, the pressure-dependent surface energy and the bulk cohesive energy of the constituent metals. The advantage of this procedure is the ability to estimate the pressure-dependent surface composition of the nanoparticles. The method has been applied to oxygen-adsorbed Pd-Ag systems; and it is found that while Ag segregate in clean particles, at higher oxygen pressures Pd atoms segregate to the surface. The present technique has been argued to be suitable for higher pressures (>10-5Torr) when coverage cannot be accurately ...

International Nuclear Information System (INIS)

The new proton-induced nuclear reaction data for C, Fe, Cu and Pb for KASKAD-S have been generated using a newly developed data preparation system. The new system utilizes the NJOY and TRANSX codes to prepare these data with the latest evaluation instead of using the SADCO code with the built-in nuclear data. Auxiliary codes have been developed to help the conversion of TRANSX output into the reaction data for running the KASKAD-S. The basic nuclear data selected for this work are the LA150 and KAERI high energy files whose energy ranges are up to 150 and 250 MeV, respectively. The total neutron yields were calculated using KASKAD-S and the new reaction data up to 250 MeV bombarding energy. The calculations were compared with the measurements or MCNPX calculations when the measured data were absent. The comparison shows that our calculations give an overall good agreement with the ...

Energy Technology Data Exchange (ETDEWEB)

Utilities looking to thrive in increasingly competitive markets are reexamining their approach to pricing. To compete effectively, utilities will need to both control costs and offer customers pricing options that are competitive and reflect the diversity in their customer base. These price structures must reflect two key factors -- marginal costs, which will increasingly reflect market prices, and consumers` responsiveness to those price structures. To accomplish this requires the capability to forecast customers` response to price structures that often provide complex signals to customers about how changes in their energy consumption and maximum power demand affect their bill, and to calculate corresponding changes in utility profits and customer net benefits. Much discussion of competitive pricing focuses on innovative new rate structures. However, significant opportunities are present to improve ...

International Nuclear Information System (INIS)

In earlier works, the inelastic mean free path (IMFP) of electrons was determined by elastic peak electron spectroscopy (EPES) using Ni and Ag reference standard samples, but fully neglecting surface excitation. Surface excitation that is characterized by the surface excitation parameter (SEP), and may affect considerably the elastic peak for the sample and the reference material. The SEP parameters of selected conducting polymers (polythiophenes, polyaniline and polyethylene) were determined by EPES using Si and Ge reference samples. Experiments were made with a hemispherical analyzer of energy resolution 100-200 meV in the E = 0.2-2.0 keV energy range. The composition of the sample surfaces was determined by in situ XPS, their surface roughness by AFM. The experimental SEP parameter data of eight polymer samples were determined by our new procedure, using the formulae of Chen and Werner et al. in the E = 0.2-2.0 keV energy range. The trial and error procedure is based on the best ...

International Nuclear Information System (INIS)

Shielding calculations for neutron-gamma radiation are usually done by using the full Theory of Transport or the Monte Carlo Techniques. After some works based on the Albedo Method, the shielding calculations for neutron-gamma radiation have a reliable tool with great didactical value which shows its clarity and simplicity for the resolution of cases that involve neutrons and photon shielding in nonmultiplying media. The excellent results of these works have motivated the elaboration and the development of this study that will be presented in this dissertation. The balance of a neutronic current entering a shield of two layers considering the coupling neutron-gamma will be determined by the Albedo Method. The shield will be composed of a layer of iron and another one of manganese with 10 cm of thickness each. The arrays of the materials coefficients will be obtained from the ANISN code. ANISN is a one dimensional ...

International Nuclear Information System (INIS)

The principal mathematical tools frequently available for calculations in Nuclear Engineering, including coupled neutron-gamma radiations shielding problems, involve the full Transport Theory or the Monte Carlo techniques. The Multigroup Albedo Method applied to shieldings is characterized by following the radiations through distinct layers of materials, allowing the determination of the neutron and gamma fractions reflected from, transmitted through and absorbed in the irradiated media when a neutronic stream hits the first layer of material, independently of flux calculations. Then, the method is a complementary tool of great didactic value due to its clarity and simplicity in solving neutron and/or gamma shielding problems. The outstanding results achieved in previous works motivated the elaboration and the development of this study that is presented in this dissertation. The radiation balance resulting from the ...

Energy Technology Data Exchange (ETDEWEB)

A risk-based sensor placement methodology is proposed to solve the problem of optimal location of sensors or detectors to protect population against the exposure to and effects of known and/or postulated chemical, biological, and/or radiological threats. Risk is calculated as a quantitative value representing population at risk from exposure against standard exposure levels. Historical meteorological data are used to characterize weather conditions as the frequency of wind speed and direction pairs. The meteorological data drive atmospheric transport and dispersion modeling of the threats, the results of which are used to calculate risk values. Sensor locations are determined via an iterative dynamic programming algorithm whereby threats captured or detected by sensors placed in prior stages are removed from consideration in subsequent stages. In addition to the risk-based placement algorithm, the proposed methodology provides a quantification ...

International Nuclear Information System (INIS)

A transient eddy current measurement method is presented to determine the thickness and conductivity of a conductive plate. The conductive plate is induced by an air-cored coil, the magnetic flux density along the axial is measured and the various signals corresponding to plates with different thickness and conductivity are calculated using a 3D transient eddy current simulator. Characteristic features are obtained from the transient response. A similarity-based modeling method is utilized in this study to estimate the thickness and conductivity of the conductive plate. (author)

Science.gov (United States)

The metal-semiconductor solar cell is a potential candidate for converting solar energy to electrical energy for space and terrestrial application. In this paper, a method for obtaining parameters of practical antireflection (AR) coatings for the metal-semiconductor solar cells is given. This method utilizes the measured equivalent index of refraction obtained from ellipsometry, since the surface to be AR coated has a multilayer structure. Both the experimental results and theoretical calculations of optical parameters for Ta/sub 2/O/sub 5/ AR coatings on Au-GaAs and Au-GaAs/sub 0.78/P/sub 0.22/ solar cells are presented for comparison. (AIP)

Energy Technology Data Exchange (ETDEWEB)

The reasons for including variance-covariance information in evaluated nuclear data files are reviewed. Accomplihments and obstacles in meeting these needs are identified. The capability to develop and utilize evaluated cross-section covariance files has been largely demonstrated, but comprehensive files of soundly based covariance data remain to be evaluated and not all types of cross-section data have yet been included. The status of the ENDF-VI covariance formats is discussed. Priorities are suggested for further development. Most effort should be concentrated to fully develop the capability to estimate the nuclear data uncertainties in quantities calculated for a broad energy spectrum. 12 refs.

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

Volumetric properties of liquid mixtures of neon and hydrogen have been calculated using path integral hybrid Monte Carlo simulations. Realistic potentials have been used for the three interactions involved. Molar volumes and excess volumes of these mixtures have been evaluated for various compositions at 29 and 31.14 K, and 30 atm. Significant quantum effects are observed in molar volumes. Quantum simulations agree well with experimental molar volumes. Calculated excess volumes agree qualitatively with experimental values. However, contrary to the existing understanding that large positive deviations from ideal mixtures are caused due to quantum effects in Ne{endash}H{sub 2} mixtures, both classical as well as quantum simulations predict the large positive deviations from ideal mixtures. Further investigations using two other Ne{endash}H{sub 2} potentials of Lennard{endash}Jones (LJ) type show that excess volumes are very ...

International Nuclear Information System (INIS)

In most conceptual fusion power reactor designs, it is proposed to use beryllium as a neutron multiplier in the blanket. Detailed chemical composition of beryllium is necessary for evaluation of the tritium breeding ratio, and estimating the activation and transmutation of beryllium in the fusion reactor. In the present report, special attention was paid to a detailed analysis of impurities in beryllium, relevant to the tritium breeding ratio evaluation. Two different methods were used for the study of impurities: an analysis of the local sample by the ICP-MS method, and an integral analysis of the beryllium assembly, using the pulsed neutron method. The latter method was proposed as the most effective way of analyzing the integral effect to impurities in beryllium on production of the tritium on the lithium-6. The evaluation of the integral effect was based on time behaviour observations of the thermal neutron flux, following the injection of a burst of D-T neutrons into the beryllium ...

Energy Technology Data Exchange (ETDEWEB)

This report presents a probabilistic safety assessment of radioactive doses as consequences from accident scenarios to complement the deterministic assessment presented in the Waste Isolation Pilot Plant (WIPP) Safety Analysis Report (SAR). The International Council of Radiation Protection (ICRP) recommends both assessments be conducted to ensure that ''an adequate level of safety has been achieved and that no major contributors to risk are overlooked'' (ICRP 1993). To that end, the probabilistic assessment for the WIPP accident scenarios addresses the wide range of assumptions, e.g. the range of values representing the radioactive source of an accident, that could possibly have been overlooked by the SAR. Routine releases of radionuclides from the WIPP repository to the environment during the waste emplacement operations are expected to be essentially zero. In contrast, potential accidental releases from postulated accident scenarios during waste ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

Nuclear Hartree-Fock (HF) + BCS calculations have led to predictions of shape isomerism in isotopes of Pt, Hg and Os nuclei. These have been confirmed through the observation of superdeformed rotational bands in {sup 190,{hor ellipsis},194}Hg. Encouraged by these measurements and similar observations in {sup 194}Pb, we have extended these calculations to a wide range of contiguous nuclei. These HF results, for {sup 192,194}Pt, {sup 190,{hor ellipsis},198}Hg and {sup 194}Pb, have been employed in a Generator Coordinate Method (GCM) calculation utilizing the quadrupole deformation as the generating variable. The resulting spectra confirm the conclusions drawn from the HF results and agree with those experiments which have been performed. Adding a phenomenological assumption for the moments of inertia of our GCM states, we can construct the radiative transitions within and out of the superdeformed band. ...

Energy Technology Data Exchange (ETDEWEB)

In the present thesis, the shell structure in exotic nuclei has been investigated. The focus of the work was on finding new experimental data in neutron-rich Cr and proton-rich Ca isotopes. The investigation of light Ca isotopes concentrated on the nucleus {sup 36}Ca which was produced in a knockout reaction from a radioactive {sup 37}Ca beam. For {sup 36}Ca, the excitation energy of the first 2{sup +} state has been measured for the first time. Furthermore, momentum distributions were analyzed using a Monte-Carlo simulation of the knockout reaction. This analysis yielded the contributions of neutrons from individual orbitals to the total knockout cross section. In principle, these may be used to calculate spectroscopic factors, but such a calculation is hampered by difficulties of present knockout-reaction models in predicting precise single-particle cross sections. The measured branching ratio to the ground and excited ...

International Nuclear Information System (INIS)

The heavy dependence on nuclear power eventually raise the issues of an efficient utilization of uranium resources, which Korea presently imports from abroad, end of a spent fuel storage. From the viewpoint that sodium-cooled fast Reactors (SFRs) have the potential of an enhanced safety by utilizing inherent safety characteristics, trans-uranics (TRU) reduction and resolving the spent fuel storage problems through a proliferation-resistant actinide recycling. SFRs are sure to be most promising nuclear power operation. The Korea Atomic Energy Research Institute (KAERI) has been developing SFR design technologies since 1997. And nowadays, the preliminary heat balance of the demonstration SFR is calculated. However, in order to verify design condition of the NSSS, it is necessary to set the heat balance and the conceptual design for BOP of the SFR as a part of the SFR design technique development business. Moreover, in order ...

Energy Technology Data Exchange (ETDEWEB)

Oestfold Research has trough the project 'Climate accounts for disposal' for Waste Norway developed a model for calculation of net greenhouse gas emissions at the disposal of various waste types. The model is based on life cycle methodology according to the standard IS014044. This model has been used for plastic packaging in the project by adapting the basic values of specific conditions in the municipality of Fredrikstad. Oestfold Research has made an assessment of greenhouse gas emissions for the recycling and material recovery of plastic packaging from households in the district on assignment from Fredrikstad municipality and compared with the current solution where plastic packaging together with residual waste is used for energy utilisation. Based on the population in Fredrikstad and estimated amount of plastic packaging waste arising per household per year the difference in climate impact was analyzed and these scenarios ...

International Nuclear Information System (INIS)

Prostate and cervical cancer patients are often treated with external X-ray beams of bi-lateral incidence. Such treatment may incur some dose effect that cannot be predicted precisely in commercial treatment planning systems (TPS) for patients having undergone total hip replacement. This study performs a Monte Carlo (MC) simulation and an analytical calculation (convolution superposition algorithm which is implemented in ADAC TPS) of a 6 MV, 5x5 cm"2 X-ray beam incident into water with the existence of hip prosthesis, e.g. Ti6Al4V and CoCrMo alloy. The results indicate that ADAC TPS cannot precisely account for the scatter and backscatter radiation that a metal hip prosthesis causes. For percent depth dose (PDD) curves, the maximum underdosage of ADAC TPS up to 5 mm above the interface between dense material and water is 5%, 20% and 27% for PDD_B_o_n_e, PDD_T_i and PDD_C_o, respectively. The dose re-buildup, which occurs behind the hip region, ...

Energy Technology Data Exchange (ETDEWEB)

An embodiment of a mercury-free fluorescent lamp combines a low pressure rare gas discharges with a phosphor having a quantum efficiency grater than one. The choice of the rare gas depends on a number of factors, one of which is the resonance transition energy. Less demand is placed the quantum efficiency of the phosphor for a lower energy resonance photon. Xenon has the lowest energy resonance transition of the stable rare gases at 8.5 eV (147 nm) and thus is a good candidate to study. The usefulness of a xenon-based discharge depends on the radiant emittance of the discharge at the resonance wavelength of 147 nm. The radiant emittance from a low pressure xenon positive column discharge is measured using two independent techniques. The first relies on the measurement of the resonance level density using absorption techniques. The effective decay rate of the resonance level is calculated using radiation trapping theory. The product of this density and trapped decay ...

Energy Technology Data Exchange (ETDEWEB)

The feasibility was evaluated using MCNP-DSP, an analog Monte Carlo transport cod to simulate source-driven measurements. Models of an isolated Westinghouse 17x17 PWR fuel assembly in a 1500-ppM borated water storage pool were used. In the models, the fuel burnup profile was represented using seven axial burnup zones, each with isotopics estimated by the PDQ code. Four different fuel assemblies with average burnups from fresh to 32 GWd/MTU were modeled and analyzed. Analysis of the fuel assemblies was simulated by inducing fission in the fuel using a {sup 252}Cf source adjacent to the assembly and correlating source fissions with the response of a bank of {sup 3}He detectors adjacent to the assembly opposite the source. This analysis was performed at 7 different axial positions on each of the 4 assemblies, and the source-detector cross-spectrum signature was calculated for each of these 28 simulated measurements. The magnitude of the ...

Science.gov (United States)

In this paper, the effects of surface mediation on the adsorption isotherm and isosteric heat of adsorption on a graphite surface were investigated, as the surface mediation is known to affect the intermolecular interaction of adsorbed molecules close to the surface. Kim and Steele (Phys. Rev. B 45 (11) (1992) 6226-6233) and others have assumed that the surface mediation is confined only to the first layer. This will be tested in this paper with a combined experimental and Grand Canonical Monte Carlo (GCMC) simulation of adsorption of argon on graphitized thermal carbon black (GTCB) over a range of temperatures (77-95.25K). By matching the simulation results against the experimental data, we have found that the surface mediation is extended up to the fourth layer, rather than only the first as suggested by Kim and Steele, and the extent of this mediation is reduced with distance from the surface. This reinforces the important role of surface on the intermolecular ...

Energy Technology Data Exchange (ETDEWEB)

Mechanisms and associated energetics for adatom diffusion on the (100) and (110) surfaces of Ni, Cu, Rh, Pd, and Ag are investigated. Self-diffusion was studied on (100) and (I 10) surfaces of Ni, Cu, Pd and Ag using corrected effective medium method (CEM) and approximation to CEM used for molecular dynamics and Monte Carlo studies (MD/MC-CEM). Self-diffusion on Pd(100), Ag(100), Ni(110), Cu(110), Pd(110), and Ag(110) is accomplished by classical diffusion: the adatom hops from its equilibrium adsorption site over an intervening bridge site to an adjacent equilibrium site. Self-diffusion on Ni(100) and Cu(100) proceeds by atomic-exchange diffusion: the adatom on the surface displaces an atom in the first surface layer. Aside from explicit inclusion of the kinetic-exchange-correlation energy, it is critical to include enough movable atoms in the calculation to insure correct energetics. Distortions induced by these diffusion mechanisms, ...

International Nuclear Information System (INIS)

The field of neutron imaging has a broad scope of applications and has played a pivotal role in visualizing and quantifying hydrogenous masses in metallic matrices. The field continues to expand into new applications with the installation of new neutron imaging facilities. In this scope, a neutron imaging facility for computed tomography and real-time neutron radiography is currently being developed around 2.0 MW TRIGA MARK-II Reactor at Maamora Nuclear Research Centre in Morocco (CENM). The neutron imaging facility consists of a neutron collimator, a real-time neutron imaging system and imaging process systems. In order to reduce the gamma-ray content in the neutron beam, the reactor tangential channel was selected. For power of 250 kW, the corresponding thermal neutron flux measured at the inlet of the tangential channel is around 3.1011 n*cm2/s. This facility will be based on a conical neutron collimator with two circular diaphragms with diameters of 4 cm and 2 cm corresponding to ...

International Nuclear Information System (INIS)

This paper discusses the economics of legumes irradiation such as Chickpea,Lupin,Kidny Bean and broad and the effect of various parameters on unit processing costs. It provides a model for calculating specific unit processing costs by correlating known capital costs with annual operation cost an annual throughputs. We analysed the cost-benefit of the proposed grain irradiation facility. We took into account the cost of the capital investment, operation and other additional parameters and then estimated the unit processing cost. The investment criteria utilized for commercial evaluation were internal rate of return (I.I.R), pay back period (P.B.P), and average rate of return (A.R.R). The irradiation cost and the additional income are also discussed. The results of this analysis showed that the installation of an irradiation unit for legumes processing in Egypt would be economically feasible.

Energy Technology Data Exchange (ETDEWEB)

The coal-fired combined cycle with partial gasification and fluidized bed combustion (PGFBC-CC), also referred to as a hybrid cycle, has advantages of staged energy conversion and utilization, which can attain high thermal efficiency with low emissions. Four kinds of PGFBC-CC are studied in this paper, two based on pressurized fluidized bed combustion (PFBC) and two on atmospheric fluidized bed combustion (AFBC). Thermal performance calculations and parametric analyses were performed. On the basis of the results, from the above analyses, the best integration system for China is suggested. In addition, a preliminary exergetic analysis is carried out for three of the PGFBC-CC variants.

Energy Technology Data Exchange (ETDEWEB)

Modeling calculations on the solubility of americium have indicated that basic americium carbonate, and not americium trihydroxide, is the solubility-controlling solid in the pH range from 6 to 10 under the influence of atmospheric CO{sub 2}. The solubility of crystalline {sup 243}AmOHCO{sup 3} has been investigated in batch experiments in near-neutral and basic solutions as a function of dissolution time in 0.1 M NaClO{sup 4} at room temperature under oxic conditions. After the solutions reached steady-state conditions, the influence of dissolved solids on the americium concentration in the supernatant solution was studied by utilizing several experimental methods to separate the solution phase from the solid. The solids were characterized by X-ray powder diffraction analysis.

British Library Electronic Table of Contents (United Kingdom)

Background: This study investigates the psychometric properties of the Patient Health Questionnaire-2 (PHQ-2) in the general population of Hong Kong. Methods: Random sampling was used to recruit 6028 participants aged 15years or over. Among them, 203 were surveyed twice within a two-week period. Participants completed the Chinese version of the PHQ-9 (including 2 items of the PHQ-2), the Chinese Health Questionnaire, the Happiness Scale, the SF-12, and questions about diagnosis and health service utilization. Internal consistency, test-retest reliability, construct and discriminant validity of the PHQ-2 were assessed. Results: Cronbach's a was 0.76. The test-retest reliability over two weeks calculated by intraclass correlation was 0.70. Spearman correlation results showed that the PHQ-2 s...

Energy Technology Data Exchange (ETDEWEB)

Rice husk generated as a by-product of rice processing is an important energy resource. The availability of this resource in India has been assessed and the technologies for exploitation of its energy potential in the rice processing industry discussed. Nomographs have been developed for estimation of the husk required to meet the energy of parboiling, drying and milling operations. The unit cost of electricity using rice husk gasifier-based power generation systems has been calculated and its financial feasibility assessed in comparison with utility-supplied and diesel-generated electricity. With the cost and efficiency data assumed here, the unit cost of electricity produced by rice husk gasifier-dual fuel engine-generator system varies between Rs 2/kWh and Rs 7/kWh. (35 Rs approximates to SUS 1.). (author)

Energy Technology Data Exchange (ETDEWEB)

The steps in assembling the computational tools needed to simulate the explosive fracture of oil shale have been described. The resulting code, with its input data, then was used to simulate 3 explosive field experiments. The results of the calculations are in good agreement with what actually occurred in the field. Further detailed comparisons are in progress for these experiments and the others that have been conducted. The development of computer codes as tools to predict rock breakage makes a variety of studies possible. The properties of the explosive can be changed to see how the extent of rubbling is affected. Studies of spacing and delays for decked charges also are possible. The codes can be applied in situations, such as confined-volume blasting, at the frontiers of blasting technology. These areas are vital to the effective utilization of oil shale resources, especially with in situ techniques. 13 references.

Energy Technology Data Exchange (ETDEWEB)

An exergoeconomic model of a vertical ground-source heat pump residential heating system presented in this study uses exergy and cost energy mass (EXCEM) methods. The data obtained from a ground-source heat pump (GSHP) residential heating system installed at the Solar Energy Institute, Ege University, Turkey, are utilized for calculations at different reference temperature values in the range 0-25{sup o}C. The performance of the geothermal heat pump residential heating system is evaluated to indicate how exergoeconomic parameter values change with system. We also undertake a parametric study to investigate how varying reference temperatures will affect the exergoeconomic analysis of the GSHP system. A correlation between the ratio of thermodynamic loss rate to capital cost and reference state temperature is developed. (author)

CERN Document Server

Utilizing form factors calculated within the light-cone sum rules, we have evaluated the decay branching ratios of $B_s\\to \\phi\\gamma$ and $B_s\\to \\phi \\ell^+\\ell^-$ in a single universal extra dimension model (UED), which is viewed as one of the alternative theories beyond the standard model (SM). For the decay $B_s \\to \\phi \\ell^+\\ell^-$, the dilepton invariant mass spectra, the forward-backward asymmetry, and double lepton polarization are also calculated. For each case, we compared the obtained results with predictions of the SM. In lower values of the compactification factor 1/R, the only parameter in this model, we see the considerable discrepancy between the UED and SM models. However, when 1/R increases, the results of UED tend to diminish and at $1/R = 1000 \\mathrm{GeV}$, two models have approximately the same predictions. Compared with data from CDF of $B_s \\to \\phi \\mu^+ \\mu^-$, the 1/R tends to ...

International Nuclear Information System (INIS)

In the conventional visualization system for the computational results, only Japanese (Nihongo) Line Printer (NLP) was available to print two dimensional cross sectional plots of vector and scalar fields. To evaluate the phenomena, an analyst had to print many plots on the NLP. This task makes difficult to check the computational results immediately after the calculation. Recently, as the visualization tools, we introduced Micro AVS and Field View which are utilized widely in the scientific and the industrial fields. In order to show the numerical results on the visualization software, we constructed a post processing system which convert the results of the numerical code to 'intermediate files' which can be read by the visualization tools. As using this system, the examination of the numerical results can be executed on the display of the personal computer. Furthermore, the persuasive report and paper with high quality can be produced due to ...

Energy Technology Data Exchange (ETDEWEB)

A brief comparative review of possible mercury free fluorescent lighting technologies is presented, including rare-gas positive column discharges, molecular discharges, and dielectric barrier discharges. Detailed experimental results on xenon positive column discharges will then be considered. In order to judge whether xenon-based discharges are a viable UV source it is necessary to measure the radiant emittance (power per unit area) for the vacuum ultraviolet (VUV) resonance xenon emission at 147 nm. Two techniques to determine the VUV radiant emittance have been developed and applied to xenon discharges. One method combines the measured resonance level density using absorption spectroscopy and a calculation of the trapped decay rate for the resonance radiation to arrive at the radiant emittance at 147 nm. A second method utilizes a direct measurement of the radiance (power per unit area per unit solid angle) at 147 nm using a calibrated VUV ...

International Nuclear Information System (INIS)

Non-invasive methods are described for estimating local cerebal blood flows (LCBF) and local partition coefficients (L#lambda#) during inhalation of 30 % stable xenon gas (Xe) in oxygen during CT scanning. After the denitrogenation with pure oxygen breathing, 30 % Xe is inhaled for four minutes to minimize subanesthetic effects with a rubber facemask and the delivery system of Xe. Local time-#DELTA# Hounsfield units curve during the Xe wash-in and wash-out phase is utilized in order to calculate L#lambda# and LCBF using a least squares curve fitting analysis. Calculated L#lambda# and LCBF with the new method manifested reasonable distribution between the grey and white matters, and reproducibility was excellent in our study. Several case studies of patients with cerebral infarction are presented to demonstrate the characterization of L#lambda# and LCBF patterns in various tissues and theoretical grounds underlying the new ...

Science.gov (United States)

The Process Waste Treatment Plant (PWTP) at the Oak Ridge National Laboratory is designed to remove radioactive contaminants, principally {sup 90}Sr, from process wastewater. Planned upgrades to the PWTP will use chabazite zeolite columns. Pilot-scale studies have shown that mass transfer zone lengths increase from 10 to about 30 cm as the superficial velocity increases from 5.5 to 22 cm/min. Calculations with a multicomponent equilibrium model showed that the distribution coefficient for strontium remains essentially constant over the process conditions, suggesting that a simple kinetic model (the Rosen long-bed solution) should adequately represent breakthrough behavior. Using a distribution coefficient of 4.87 L/g predicted by the equilibrium model, good agreement was found between experimental breakthrough curves and those calculated with the Rosen solution. This model allows prediction of bed depths and cycle times necessary to achieve the ...

KoreaScience (Korea)

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International Nuclear Information System (INIS)

Nuclear fuel vendors in Japan are now studying reprocessed uranium (RepU) fuel in order to prepare for full scale utilization in the future. Separate studies are made for PWR and BWR fuel. The study consists of 2 phrases. The purposes of phase-1 are to understand various RepU characteristics in the fuel fabrication process, to analyze the core characteristics by loading RepU assemblies, to solve the problems clarified in the study, and to collect basic data for licensing. In phase-2, the effects of impurities on the fabrication process will be evaluated, and the safety of RepU fuel manufacturing will be confirmed with a RepU fuel fabrication campaign in 1990. The neutronic data will be collected after insertion into power reactors, and the data will be used to verify plant safety for full utilization of RepU in the future. This paper summarizes the phase-1 study results. 1. RepU Characteristics. The internal and external radiation exposures due ...

International Nuclear Information System (INIS)

A Monte Carlo simulation of the vacuum Bianchi type-IX (mixmaster) cosmology yields a significant correlation between large universe volume and high anisotropy. An analog of the model's chaotic classical behavior is seen in the break up of the universe wave function at large volume into fingers in the corners of the minisuperspace anisotropy potential.

UK PubMed Central (United Kingdom)

The reference medium for brachytherapy dose measurements is water. Accuracy of dose measurements of brachytherapy sources is critically dependent on precise measurement of the source–detector...Full Text Available

International Nuclear Information System (INIS)

This work reports on the use of three state-of-the-art Monte Carlo codes (MCNPX, PENELOPE, FLUKA) in the efficiency calibration of a Broad-Energy Germanium (BEGe) detector. Initial discrepancies found between the experimental and computational efficiency values are related to the poor knowledge of some physical parameters of the detector (dead-layers, crystal dimensions, etc.). As a consequence, a sensitivity analysis was carried out. Each parameter was systematically analyzed, and an accurate model of the detector was determined. The obtained results are consistent, allowing this model to be used in computational efficiency calibrations of the equipment at stake.

International Nuclear Information System (INIS)

We have studied the application of direct aperture optimization (DAO) as an inverse planning tool for breast IMRT. Additionally, we have analysed the impact of respiratory motion on the quality of the delivered dose distribution. From this analysis, we have developed guidelines for balancing the desire for a high-quality optimized plan with the need to create a plan that will not degrade significantly in the presence of respiratory motion. For a DAO optimized breast IMRT plan, the tangential fields incorporate a flash field to cover the range of respiratory motion. The inverse planning algorithm then optimizes the shapes and weights of additional segments that are delivered in combination with the open fields. IMRT plans were generated using DAO with the relative weights of the open segments varied from 0% to 95%. To assess the impact of breathing motion, the dose distribution for the optimized IMRT plan was recalculated with the isocentre sampled from a predefined distribution in a ...

Energy Technology Data Exchange (ETDEWEB)

An analysis of the energy level structure of Cr{sup 3+} ions in Cs{sub 2}NaAlF{sub 6} crystal is performed using the exchange charge model (ECM) together with the crystal field analysis/microscopic spin Hamiltonian (CFA/MSH) computer package. Utilizing the crystal structure data, our approach enables modelling of the crystal field parameters (CFPs) and thus the energy level structure for Cr{sup 3+} ions at the two crystallographically inequivalent sites in Cs{sub 2}NaAlF{sub 6}. Using the ECM initial adjustment procedure, the CFPs are calculated in the crystallographic axis system centred at the Cr{sup 3+} ion at each site. Additionally the CFPs are also calculated using the superposition model (SPM). The ECM and SPM predicted CFP values match very well. Consideration of the symmetry aspects for the so-obtained CFP datasets reveals that the latter axis system matches the symmetry-adapted axis system related directly to the ...

International Nuclear Information System (INIS)

Recent advances in self-amplified spontaneous emission (SASE) experiments stimulate interest in quantitative comparison of measurements with theory. In this paper we show that the widely used simulation code TDA3D, developed by Tran and Wurtele [Comput. Phys. Commun. 54, 263 (1989)] even though a single frequency code, can be used to determine the output power in the SASE process with excellent approximation in the exponential growth regime. The method applies when the gain is not very high, which is a special advantage, because when the gain is not very high, the analytical calculation is particularly difficult since the exponential growing term does not dominate. The analysis utilizes a scaling relation between the output power and the number of simulation particles in the code TDA3D: left-angle P right-angle=N_#lambda#"'/N_#lambda# left-angle P"'right-angle, where left-angle P right-angle is the output power and N_#lambda# is the line ...

Energy Technology Data Exchange (ETDEWEB)

Fermilab experiment E791 took data during six months in 1991 using a 500 GeV {pi}{sup -} beam on platinum and diamond targets for the purpose of studying the production and decay of particles containing a charm quark. In this dissertation, results are presented on the production of the D{sup 0} and {anti D}{sup 0} mesons using fully reconstructed D{sup 0}{yields}K{pi} and D{sup 0}{yields}K{pi}{pi}{pi} decays. Specifically, the total forward production cross section is measured as well as differential cross sections as a function of the scaled longitudinal momentum, Feynman-x (x{sub F}), and the transverse momentum squared (p{sub T}{sup 2}). The results are compared to theoretical predictions from a next-to-leading order (NLO) calculation and from a leading order Monte Carlo event generator, PYTHIA/JETSET, which uses parton showers to account for higher-order terms. The comparison is made to both the c quark predictions and the predictions for D ...

Science.gov (United States)

Legal aspects of using natural gas as boiler fuel for electric utilities are reviewed through one utility's challenges to the Power Plant and Industrial Fuel Use implementation. ASARCO vs. FPC, 1973, and City of Willcox vs. FPC are discussed. (PSB)

International Nuclear Information System (INIS)

This work come along of the necessity to utilize an unique High-Energy Electron Linear Accelerator (10 MV) for radiant treatments which require higher doses in the surface levels of tissue. It is analyzed the interposition of acrylic degraders (spoilers) in the beam, especially for opposed and parallel fields in the cases of head and neck. It was analyzed the possible combinations of the following parameters: 1) Field sizes defined at isocenter (100 cm) 6 x 6 cm"2, 8 x 8 cm"2 and 10 x 10 cm"2 ; 2) Surface-spoiler distance (DSS) of 4, 7 and 10 cm; 3) Spoilers with different thickness 1.1 and 1.5 cm. It was observed a displacement of the maximum dose toward the surface, and an increase in the percentile doses in the build-up zone when the spoiler is nearing and/or increasing its thickness. It is verified that the use of spoilers, support the symmetry and plane of the beam inside of the clinically acceptable margins. When the results obtained are analyzed then it is ...

Energy Technology Data Exchange (ETDEWEB)

Molar excess volumes, V{sup E}, molar excess enthalpies, H{sup E}, and speeds of sound, u, of o-toluidine (i) + cyclohexane or n-hexane or n-heptane (j) binary mixtures have been determined over entire range of composition at 308.15 K. Speeds of sound data have been utilized to predict isentropic compressibility changes of mixing, {kappa}{sub S}{sup E} of (i + j) mixtures. The observed V{sup E}, H{sup E} and {kappa}{sub S}{sup E} data have been analyzed in terms of Graph theory. The analysis of V{sup E} data by Graph theory reveals that o-toluidine exists as an associated molecular entity and (i + j) mixtures contain 1:1 molecular complex. It has been observed that V{sup E}, H{sup E} and {kappa}{sub S}{sup E} values calculated by Graph theory compare well with their corresponding experimental values. The observed data have also been analyzed in term of Flory theory.

International Nuclear Information System (INIS)

The RADionuclide Transport, Removal, And Dose (RAD-TRAD) code is designed for U.S. Nuclear Regulatory Commission (USNRC) use to calculate the radiological consequences to the off-site population and to control room operators following a design-basis accident at light water reactor (LWR) power plants. This code utilizes updated reactor accident source terms published in draft NUREG-1465. The code will track the transport of radionuclides as they are released from the reactor pressure vessel, travel through the primary containment and other buildings, and are released to the environment. As the radioactive material is transported through the primary containment and other buildings, credit for several removal mechanisms may be taken, including sprays, suppression pools, overlying pools, filters, and natural deposition. Simple models are available for these different removal mechanisms that use, as input, information about the conditions in the ...

Energy Technology Data Exchange (ETDEWEB)

Optimal capacitor placement determines the size, type, and location of capacitors to be installed on a radial distribution feeder that will reduce peak power and energy losses while minimizing the costs of investment and installation of the capacitor banks. This paper describes a sensitivity-based optimal placement of capacitors that employs a new load characterization scheme using a voltage-current-angle-logger. The proposed method allows modeling of loads of different power factors for different portions of the distribution feeder. The optimal solution is obtained by testing various combinations of capacitor banks (based on the smallest bank size specified by the user) and candidate nodes along the distribution feeder, and calculating the resultant savings. In order to reduce solution time, the candidate nodes are ranked according to their sensitivity factors. The highest ranking nodes are considered first in the optimization process. At a node where the ...

Energy Technology Data Exchange (ETDEWEB)

This report for the Swiss Federal Office of Energy (SFOE) presents the results of a study carried out on the Norwegian electricity market 10 years after its liberalisation. The similarity of the Norwegian market to the Swiss electricity market is discussed. Similarly to the proposed situation in Switzerland, the liberalisation in Norway foresaw no privatisation of public utilities and a model for the regulation of grid access was introduced. The report describes and comments on the various phases in which the liberalisation occurred and examines the various instruments used, e.g. to ensure that individual grid operators did not make undue profits from their monopoly. The methods used for the monitoring of grid operators' costs are described and the mechanisms involved in the definition of prices for grid services are examined, including measures taken when profits were too high or too low. The report is concluded with a discussion of the conclusions that ...

Energy Technology Data Exchange (ETDEWEB)

The humidification dehumidification desalination process is viewed as a promising technique for small capacity production plants. The process has several attractive features, which include operation at low temperature, ability to utilize sustainable energy sources, i.e. solar and geothermal, and requirements of low technology level. This paper evaluates the characteristics of the humidification dehumidification desalination process as a function of operating conditions. A small capacity experimental system is used to evaluate the process characteristics as a function of the flow rate of the water and air streams, the temperature of the water stream and the temperature of the cooling water stream. The experimental system includes a packed humidification column, a double pipe glass condenser, a constant temperature water circulation tank and a chiller for cooling water. The water production is found to depend strongly on the hot water temperature. Also, the water ...

Energy Technology Data Exchange (ETDEWEB)

Laser-assisted processing techniques, utilized to produce fine, metal grid patterns for high-efficiency solar cells, are being investigated, developed, and characterized. The work performed in the third quarter of this contract is detailed here. A preliminary economic evaluation has yielded the conclusion that laser-assisted pyrolysis of spun-on silver neodecanoate is the most promising of all the metallization techniques being investigated in this contract. Early adhesion problems have been solved by optimizing deposition parameters. Linewidth studies have been carried out as a function of laser power, scan speed, and film thickness. Preliminary solar cells have been fabricated and characterized using this metallization scheme. Silver neodecanoate films have also been decomposed using a pulsed uv laser and metal mask. A detailed study of the various models of localized surface temperature rise in silicon due to laser heating has been carried out. A review of this ...

Energy Technology Data Exchange (ETDEWEB)

A multi-faceted research program has been performed to investigate in detail several aspects of free and forced convective cooling of underground electric cable systems. There were two main areas of investigation. The first one, reported in Volume 1, dealt with the fluid dynamic and thermal aspects of various components of the cable system. In particular, friction factors for laminar flow in the cable pipes with various configurations were determined using a finite element technique; the temperature distributions and heat transfer in splices were examined using a combined analytical numerical technique; the pressure drop and heat transfer characteristics of cable pipes in the transitional and turbulent flow regime were determined experimentally in a model study; and full-scale model experimental work was carried out to determine the fluid dynamic and thermal characteristics of entrance and exit chambers for the cooling oil. The second major area of activity, reported in this volume, ...

Energy Technology Data Exchange (ETDEWEB)

The purpose of this project was to investigate the feasibility of an antiproton catalyzed fission fragment rocket (FFR). The FFR is characterized by the extraction of fission fragments from the fissile fuel, and the utilization of their kinetic energy for thrust generation. A significant drawback to previous FFR designs was the requirement to maintain a critical nuclear pile as the fission fragment source. The author examined the possibility of replacing the critical pile with a sub-critical pile driven by antiprotons. Recent experiments have revealed that antiprotons stimulate highly energetic fissions in {sup 238}U, with a neutron multiplicity of 13.7 neutrons per fission. This interaction was used as a throttled neutron source. The pile consisted of layers of fissile coated fibers which are designed to allow fission fragments to escape them, where the fragments collide with a fluid. The heated fluid is then ejected from the rocket to provide thrust. The ...

Energy Technology Data Exchange (ETDEWEB)

In our evaluation we utilized the Asahi Mark-J NMR-CT system, with a resistive vertical quadrupolar electromagnet (0.1 Tesla) and a proton resonance frequency of 4.5 MHz. Our main imaging methods are the inversion-recovery or IR, saturation-recovery, or SR, and calculated T/sub 1/. Difference, or D images, constructed by subtracting the data of the IR signal from that of the SR signal, have also been obtained in some cases. The system allows averaging of raw data. Hybrid images were constructed from two or more images to obtain clear definition of areas of interest. By using the hybrid image, several tissues of different relaxation times can be shown in the same image. Application in our study of the newly developed hybrid image indicates its importance in the detection and diagnosis of lesion, especially the detection of the differentiation of an edematous lesion from a tumor, and also abnormal fluid collection such as the pleural effusion or ...

Science.gov (United States)

In the past few decades the need for improved nuclear reactor safety analyses has led to a rapid development of advanced methods for multidimensional thermal-hydraulic analyses. These methods have become progressively more complex in order to account for the many physical phenomena anticipated during steady state and transient Light Water Reactor (LWR) conditions. The advanced thermal-hydraulic subchannel code COBRA-TF (Thurgood, M. J. et al., 1983) is used worldwide for best-estimate evaluations of the nuclear reactor safety margins. In the framework of a joint research project between the Pennsylvania State University (PSU) and AREVA NP GmbH, the theoretical models and numerics of COBRA-TF have been improved. Under the name F-COBRA-TF, the code has been subjected to an extensive verification and validation program and has been applied to variety of LWR steady state and transient simulations. To enable F-COBRA-TF for industrial applications, including safety margins evaluations and ...

International Nuclear Information System (INIS)

By 1970 the first edition of the ASME Code Section XI, Inservice Inspection of Nuclear Reactor Coolant Systems was published. From its inception, the Section XI inservice inspection scope was based on a fundamental risk-based selection process. In other words the inservice inspection scope included components where the consequences of a pressure boundary failure were high. Once the consequence significant system boundaries were established, inspections would then be performed at locations believed to be most susceptible service induced failure. Current Section XI requirements require that inspection locations be selected on the basis of peak stress and fatigue usage values contained in the Design Reports. These original stress calculations were designed to qualify a design and assure that the plant would provide reliable service throughout its design life. For the most part, the fatigue usage values in these reports do not provide an accurate measure of service ...

Energy Technology Data Exchange (ETDEWEB)

The exchange charge model (ECM) of crystal field is utilized to provide the theoretical explanation of the ground state absorption and the excited state absorption observed for the octahedrally coordinated Ni{sup 2+} ions in the spinel MgAl{sub 2}O{sub 4}. The ECM enables modeling of the crystal field parameters (CFPs) for the impurity ions based on the crystal structure data of the host lattice. To ensure the reliability of the CFPs, the convergence of the CFP values with the increasing number of the coordination spheres taken into account in the ECM calculations is considered. The trigonal CFPs B{sub 2}{sup 0},B{sub 4}{sup 0}andB{sub 4}{sup -3} determined by the ECM, together with the appropriate Racah parameters B and C, serve as input to two crystal field analysis computer packages, which compute the energy level schemes within the whole 3d{sup 8} configuration. The cubic approximation utilizing only one CFP Dq is also ...

International Nuclear Information System (INIS)

The Radiation Technology Center from IPEN-CNEN/SP, Brazil, developed a revolutionary design and national technology, a small-sized continuous run and multipurpose industrial gamma irradiator, to be used as a demonstration facility for manufacturers and contract service companies, which need economical and logistical in-house irradiation system alternatives. Also, to be useful for supporting the local scientific community on development of products and process using gamma radiation, assisting the traditional and potential users on process validation, training and qualification of operators and radioprotection officers. The developed technology for this facility consists of a continuous tote box transport system, comprising a single concrete vault, where the automated transport system of products inside and outside of the irradiator utilizes a rotating door, integrated with the shielding, avoiding the traditional maze configuration. Covering 76 m"2 of floor area, the ...

Energy Technology Data Exchange (ETDEWEB)

Molecular simulation aims at simulating particles in interaction, describing a physico-chemical system. When considering Markov Chain Monte Carlo sampling in this context, we often meet the same problem of statistical efficiency as with Molecular Dynamics for the simulation of complex molecules (polymers for example). The search for a correct sampling of the space of possible configurations with respect to the Boltzmann-Gibbs distribution is directly related to the statistical efficiency of such algorithms (i.e. the ability of rapidly providing uncorrelated states covering all the configuration space). We investigated how to improve this efficiency with the help of Artificial Evolution (AE). AE algorithms form a class of stochastic optimization algorithms inspired by Darwinian evolution. Efficiency measures that can be turned into efficiency criteria have been first searched before identifying parameters that could be optimized. Relative frequencies for each type ...

Science.gov (United States)

Four questions are posed: (1) Is knowledge utilization a rhetorical evocation? (2) Is the conjunction of knowledge with utility part of a cultural system of common sense? (3) Is utility a normative or a descriptive concept? and (4) How does the concept of knowledge utilization figure in the specialized discourse of social scientists? This paper analyzes the concept of knowledge utilization from the perspective of philosophy of language and philosophy of science. Knowledge utilization is a rhetorical evocation that implies concepts of action and knowledge. It is supported by two conceptual fusions. The fusion of value and utility draws on common sense, but does not exhaust colloquial understandings about knowledge and action. The conceptual fusion of knowledge and truth is consistent with common sense but disregards scientific criticism. ...

International Nuclear Information System (INIS)

The High Flux Isotope Reactor (HFIR) located at Oak Ridge National Laboratory is one of the world's most powerful research reactors. In 1996, one year after the demise of the Advanced Neutron Source Project, the U.S. Department of Energy embarked on an aggressive program to upgrade the neutron scattering facilities at the HFIR. These upgrades, which are now in progress, include the installation of larger beam tubes, a high-performance hydrogen cold source, and additional neutron guides and neutron scattering instruments. An extensive analysis effort was performed over the past 4 yr to support the design of the modified beamlines and new user facilities and to assess the impact of the upgrades on the integrity of the existing reactor system. The results of three of these analyses are summarized here. Specifically, results are presented for analyses related to the design of the new cold neutron source (CNS), the assessment of beam tube changes on the anticipated pressure vessel lifetime, ...

CERN Document Server

We demonstrate the use of a variational method to determine a quantitative lower bound on the rate of convergence of Markov Chain Monte Carlo (MCMC) algorithms as a function of the target density and proposal density. The bound relies on approximating the second largest eigenvalue in the spectrum of the MCMC operator using a variational principle and the approach is applicable to problems with continuous state spaces. We apply the method to one dimensional examples with Gaussian and quartic target densities, and we contrast the performance of the basic Metropolis-Hastings algorithms with a ``smart'' variant that incorporates gradient information into the trial moves. We find that the variational method agrees quite closely with numerical simulations. We also see that the smart MCMC algorithm often fails to converge geometrically in the tails of the target density except in the simplest case we examine, and even then care must be taken to choose the appropriate ...

CERN Document Server

An algorithm for creating synthetic telescope images of Smoothed Particle Hydrodynamics (SPH) density fields is presented, which utilises the adaptive nature of the SPH formalism in full. The imaging process uses Monte Carlo Radiative Transfer (MCRT) methods to model the scattering and absorption of photon packets in the density field, which then exit the system and are captured on a pixelated image plane, creating a 2D image (or a 3D datacube, if the photons are also binned by their wavelength). The algorithm is implemented on the density field directly: no gridding of the field is required, allowing the density field to be described to an identical level of accuracy as the simulations that generated it. Some applications of the method to star and planet formation simulations are presented to illustrate the advantages of this new technique, and suggestions as to how this framework could support a Radiative Equilibrium algorithm are also given as an indication for ...

International Nuclear Information System (INIS)

The Monte-Carlo method and experimental methods were used to determine the neutron fluxes in the irradiation channels of the Ghana Research Reactor -1. The MCNP5 code was used for this purpose to simulate the radial and axial distribution of the neutron fluxes within all the ten irradiation channels. The results obtained were compared with the experimental results. After the MCNP simulation and experimental procedure, it was observed that axially, the fluxes rise to a peak before falling and then finally leveling out. Axially and radially, it was also observed that the fluxes in the centre of the channels were lower than on the sides. Radially, the fluxes dip in the centre while it increases steadily towards the sides of the channels. The results have shown that there are flux variations within the irradiation channels both axially and radially. (au)

Energy Technology Data Exchange (ETDEWEB)

Oil/electric heating systems and energy measuring instrumentation were installed in 50 houses in Deep River, Ontario. These were operated and monitored for two heating seasons to demonstrate their performance and determine the percentage oil placement as a function of heater capacity and control system. All experimental data was stored and processed by computer. It was found that oil furnace utilization efficiency varied from 48 to 59% for an average of 53.5%. Oil displacement ranged from 49 to 83% for 2.5 and 5.0 kW electric heaters controlled by two-stage indoor thermostats. Fuel costs for oil/electric hybrid heating, with 5.0 kW plenum heaters and indoor two-stage thermostats, were 20% less than for oil heating, based on average furnace efficency and 1983 January retail fuel prices. Annual load factors above 37% were achieved for plenum heaters compared to 11.9% for all-electric systems. Space heating requirements were proportional to heating degree days ...

Energy Technology Data Exchange (ETDEWEB)

Sandia National Laboratories, New Mexico, conducts the Utility Battery Storage Systems Program, which is sponsored by the US Department of Energy`s Office of Energy Management. The goal of this program is to assist industry in developing cost-effective battery systems as a utility resource option by 2000. Sandia is responsible for the engineering analyses, contracted development, and testing of rechargeable batteries and systems for utility energy storage applications. This report details the technical achievements realized during fiscal year 1994.

KoreaScience (Korea)

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KoreaScience (Korea)

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International Nuclear Information System (INIS)

... no. 2) p. 27-28. economics hydrogen power reactors nonmetals (ELEMENTS

International Nuclear Information System (INIS)

... electric utilities electrochemistry energy storage fuel cells organizational models

Energy Technology Data Exchange (ETDEWEB)

Increasingly, utility organizations recognize the value of sharing data and applications among their computing environments. A typical utility`s computing environment may consist of disparate computer platforms. The focus of this paper is to highlight importance of a documented information technology architecture for identifying business perspectives for interoperability, and to brief utility management about the Electric Power Research Institute`s (EPRI) accomplishment along these same lines.

International Nuclear Information System (INIS)

In areas where radiation dose monitoring has not been performed, it is essential to use material available in the environment be able to rapidly assess doses to individuals for immediate emergency medical care or for general estimation of the radiological consequences. It was shown that certain types of telephone cards containing microchips have the potential to be used as individual radiation dosimeters in emergency situations to detect doses over 250 mGy by luminescence measurements. In order to understand the dosimetric properties of chip cards, the components obtained from INFINIEON Company at various stages of production were used for luminescence measurements. It is found that the protecting layer used above the chips so called 'globe top' is the main source of radiation induced signal in chip cards. The globe top produced by INFINIEON at that stage is found to contain SiO2 and Epoxy. In order to improve the dosimetric properties of the chip cards, the raw material of the globe ...

International Nuclear Information System (INIS)

Full text of publication follows: The TUV NORD e.V. is an independent Technical Support Organisation (TSO) performing safety assessments in almost every field of technology. In nuclear safety the TUV can look back on more than 40 years of experience. In the last years in Germany PWR safety analyses were focussed on boron dilution events with the potential of reactivity transients. The possibility of coolant with a low boron concentration collected in localized areas of the reactor coolant system (RCS) can be caused by injection of coolant with less boron content from interfacing systems (external dilution) as well as separation of borated reactor coolant into highly concentrated and diluted fractions (inherent dilution). Inherent dilution can e.g. occur after reflux-condenser heat transfer after a small break loss of coolant accident (SBLOCA) with a limited operability of the emergency core cooling (ECC) systems. The TUV Nord e.V. was charged by German supervisory authorities with the ...

Energy Technology Data Exchange (ETDEWEB)

The electrogeometric model cannot consider the influence of some parameters on the screening of the wire conductor of the H.V. lines. For analysing the influence of these parameters (the conductor potential, the influence of the distance from phase conductor to earth wire, the influence of the reducing factor of the striking earth distance, the earth slope, etc.), the Monte Carlo method is preferable. The influence of the earth slope on the screening effect of the wire conductor for different conditions is presented in this paper. (author)

Energy Technology Data Exchange (ETDEWEB)

A Monte Carlo simulation of the vacuum Bianchi type-IX (mixmaster) cosmology yields a significant correlation between large universe volume and high anisotropy. An analog of the model's chaotic classical behavior is seen in the break up of the universe wave function at large volume into fingers in the corners of the minisuperspace anisotropy potential.

Science.gov (United States)

The Milstar communications satellite system will provide secure antijam communication capabilities for DOD operations into the next century. In order to accomplish this task, the Milstar system will employ precise timekeeping on its satellites and at its ground control stations. The constellation will consist of four satellites in geosynchronous orbit, each carrying a set of four rubidium (Rb) atomic clocks. Several times a day, during normal operation, the Mission Control Element (MCE) will collect timing information from the constellation, and after several days use this information to update the time and frequency of the satellite clocks. The MCE will maintain precise time with a cesium (Cs) atomic clock, synchronized to UTC(USNO) via a GPS receiver. We have developed a Monte Carlo simulation of Milstar's space segment timekeeping. The simulation includes the effects of: uplink/downlink time transfer noise; satellite crosslink time transfer noise; satellite ...

Energy Technology Data Exchange (ETDEWEB)

We present our plans for a Monte-Carlo code simulating all possible combinations of (electromagnetic) interactions between colliding electron, positron, and both high-energy and laser photon beams, based on the ABEL code for beam-beam interaction. The implementation and first results for the laser-e{sup -} interaction are described. ((orig.)).

Energy Technology Data Exchange (ETDEWEB)

The theory of neutron moderation and spectroscopy are briefly reviewed, and moderators that are useful for Bonner sphere spectrometers are discussed. The choice of the neutron detector for a Bonner sphere spectrometer is examined. Spectral deconvolution methods are briefly reviewed, including derivative, parametric, quadrature, and Monte Carlo methods. Calibration is then discussed. (LEW)

Energy Technology Data Exchange (ETDEWEB)

From out of the numerous technical alternatives the manual develops a waste management concept with emphasis on methods which can be coordinated for maximum ecological use and minimum economic costs. A clear-cut analysis of the present state of waste utilization and waste disposal in the Federal Republic of Germany (chapter 1) is followed by a detailed description of conventional and modern state-of-the-art waste utilization methods based on ecological evaluation criteria (chapter 3). An optimum waste utilization concept for defined quantities of wastes is derived from the ecological and economic comparison of waste utilization techniques given in chapter 3. Chapter 4 points out different variants of waste utilization and waste disposal methods and shows how to determine the optimum variant of the optimum concept for a particular area or community. (orig.).

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

A method for calculating plume rise above stack level is presented. The equations set forth by Briggs, which are presently the most popular for such calculations, are discussed. A method using 2 nomographs, simplifying the calculations is given. (JMT)

International Nuclear Information System (INIS)

Delayed neutron energy spectra have been measured for six delay-time intervals following the fast fission of "2"3"8U nuclei. The delay-time intervals span the range 0.17 to 10.2 seconds following initial fission while the measured spectra span neutron energies from 10 keV to 4 MeV. The experiment was performed utilizing the UMass/Lowell 5.5 MV Van de Graff accelerator to produce fast neutrons for inducing fission in a "2"3"8U lined fission chamber. The fission fragments were flushed via a helium jet stream to a well-shielded counting room where they were deposited onto a moving tape (magnetic audio tape) and transferred to a beta-neutron time-of-flight spectrometer. By adjusting the tape speed, composite delayed neutron time-of-flight spectra were measured for several different delay-time intervals. These measurements involved beta-neutron coincidences with "6Li-loaded glass scintillators for neutron energies from 10 keV to 450 keV and Bicron BC 501 liquid ...

Science.gov (United States)

The paper is an overview of utility flue gas desulfurization (FGD) technology and costs. The two commercially offered throwaway and salable product systems that are considered to be the most important for near-term (through 1990) SO2 control are: throwawa...

Energy Technology Data Exchange (ETDEWEB)

CSIRO is Australia's one and only federal government research organization. After a description of Australian coal resources and coal-related research, accounts are given of the selection of research topics at CSIRO and of the coal utilization and coal liquefaction research which is being undertaken.

UK PubMed Central (United Kingdom)

This article explores the effects of reimbursement and utilization control policies on utilization patterns and spending for physician and hospital outpatient services under state Medicaid programs....Full Text Available

Energy Technology Data Exchange (ETDEWEB)

This plan details the methods and procedures necessary to ensure a safe transition in the operation of the Light Duty Utility Arm (LDUA) System. The steps identified here outline the work scope and identify responsibilities to complete startup, and turnover of the LDUA to Characterization Project Operations (CPO).

Energy Technology Data Exchange (ETDEWEB)

This article describes the processes for the treatment of plastic waste: sampling, sorting, comminution. The requirements for the different processes for waste treatment (as recycling, utilization as raw material, energy recovery, combustion) are listed. (SR)

Science.gov (United States)

... Accession Number : ADB323076. Title : The Detailing Process Information Technology and NEC Utilization. Descriptive Note : Final rept. ...

Science.gov (United States)

as magnetic forming and hot-drape forming. Details about the 25 techniques discussed incorporate the most recent improvements and ...

Science.gov (United States)

... conditions. the Air Force Research Laboratory's Aural Displays and The advent of virtual audio technology provides as many ...

Energy Technology Data Exchange (ETDEWEB)

Geothermal heat pump systems are a promising new energy technology that has shown rapid increase in usage over the past 10 years in the United States. These systems offer substantial benefits to consumers and utilities in energy (kWh) and demand (kW) savings. The purpose of this study was to determine what existing monitored data were available mainly from electric utilities on heat pump performance, energy savings, and demand reduction for residential, school, and commercial building applications. Information was developed on the status of electric utility marketing programs, barriers to market entry, incentive programs, and benefits.

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

Sandia National Laboratories, New Mexico, conducts the Utility Battery Storage Systems Program, which is sponsored by the US Department of Energy`s Office of Energy Management. In this capacity, Sandia is responsible for the engineering analyses, contract development, and testing of rechargeable batteries and systems for utility-energy-storage applications. This report details the technical achievements realized during fiscal year 1993.

International Nuclear Information System (INIS)

The use of robots in powerplants is an option that can no longer be ignored. Robots can reduce worker exposure to harmful environments and minimize downtime. As a result, electric utilities are using them more than ever. As robots become more widely accepted, more are being developed to handle an expanding variety of applications. This report begins with an overview of the use of robotics in the electric-utility industry; following that are sections detailing applications for nuclear plants, fossil-fired stations, and transmission and distribution facilities.

Energy Technology Data Exchange (ETDEWEB)

Past and current development of coal utilization technology in the Japanese steel industry is reviewed and some projects currently under research and development briefly described. These include DIOS, an iron making process which directly utilizes both iron ore and coal without a sintering plant or a coke oven; and the development of a new generation coke oven. 15 figs.