Radiation Doses to Hanford Workers from Natural Potassium-40 (open access)

Radiation Doses to Hanford Workers from Natural Potassium-40

The chemical element potassium is an essential mineral in people and is subject to homeostatic regulation. Natural potassium comprises three isotopes, 39K, 40K, and 41K. Potassium-40 is radioactive, with a half life of 1.248 billion years. In most transitions, it emits a β particle with a maximum energy of 0.560 MeV, and sometimes a gamma photon of 1.461 MeV. Because it is ubiquitous, 40K produces radiation dose to all human beings. This report contains the results of new measurements of 40K in 248 adult females and 2,037 adult males performed at the Department of Energy Hanford Site in 2006 and 2007. Potassium concentrations diminish with age, are generally lower in women than in men, and decrease with body mass index (BMI). The average annual effective dose from 40K in the body is 0.149 mSv y−1 for men and 0.123 mSv y−1 women respectively. Averaged over both men and women, the average effective dose per year is 0.136 mSv y−1. Calculated effective doses range from 0.069 to 0.243 mSv y−1 for adult males, and 0.067 to 0.203 mSv y−1 for adult females, a roughly three-fold variation for each gender. The need for dosimetric phantoms with a greater variety of BMI values …
Date: February 13, 2009
Creator: Strom, Daniel J.; Lynch, Timothy P. & Weier, Dennis R.
Object Type: Report
System: The UNT Digital Library
Three-dimensional lithographically-defined organotypic tissue arrays for quantitative analysis of morphogenesis and neoplastic progression (open access)

Three-dimensional lithographically-defined organotypic tissue arrays for quantitative analysis of morphogenesis and neoplastic progression

Here we describe a simple micromolding method to construct three-dimensional arrays of organotypic epithelial tissue structures that approximate in vivo histology. An elastomeric stamp containing an array of posts of defined geometry and spacing is used to mold microscale cavities into the surface of type I collagen gels. Epithelial cells are seeded into the cavities and covered with a second layer of collagen. The cells reorganize into hollow tissues corresponding to the geometry of the cavities. Patterned tissue arrays can be produced in 3-4 h and will undergo morphogenesis over the following one to three days. The protocol can easily be adapted to study a variety of tissues and aspects of normal and neoplastic development.
Date: February 13, 2008
Creator: Nelson, Celeste M.; Inman, Jamie L. & Bissell, Mina J.
Object Type: Article
System: The UNT Digital Library
Progress with Tevatron Electron Lenses (open access)

Progress with Tevatron Electron Lenses

None
Date: September 13, 2007
Creator: Kamerdzhiev, V.; Alexahin, Y.; Kuznetsov, G. F.; Shiltsev, V. D. & Zhang, X.
Object Type: Article
System: The UNT Digital Library
New Equalizers for Antiproton Stochastic Cooling at Fermilab (open access)

New Equalizers for Antiproton Stochastic Cooling at Fermilab

In the continuous effort to improve antiproton stacking rate, a new type of equalizers has been developed and installed in antiproton accumulator. The R&D of these new equalizers is described in this paper. Equalizers are used in Fermilab antiproton stochastic cooling to compensate frequency response of the cooling system. Usually both amplitude and phase compensations are needed. However in most cases it is difficult to achieve a satisfactory compensation for both because of their interdependence. To make it more difficult is that in some cases large compensations (10 to 20 db of amplitude compensation or more than 100 degree of phase compensation) are needed near the low or high ends of a frequency band. Recently a new compensation scheme of equalizers is proposed for Fermilab antiproton accumulator. This scheme originated from the requirement to maximize the system performance resulting in a request for the phase of the cooling system transfer function to be extremely flat. For this kind of phase correction, a new type of equalizers has been developed.
Date: September 13, 2007
Creator: Lebedev, V. A.; Pasquinelli, R. J. & Sun, D.
Object Type: Article
System: The UNT Digital Library
Exp6-polar thermodynamics of dense supercritical water (open access)

Exp6-polar thermodynamics of dense supercritical water

We introduce a simple polar fluid model for the thermodynamics of dense supercritical water based on a Buckingham (exp-6) core and point dipole representation of the water molecule. The proposed exp6-polar thermodynamics, based on ideas originally applied to dipolar hard spheres, performs very well when tested against molecular dynamics simulations. Comparisons of the model predictions with experimental data available for supercritical water yield excellent agreement for the shock Hugoniot, isotherms and sound speeds, and are also quite good for the self-diffusion constant and relative dielectric constant. We expect the present approach to be also useful for other small polar molecules and their mixtures.
Date: December 13, 2007
Creator: Bastea, S & Fried, L E
Object Type: Article
System: The UNT Digital Library
Soft Phonons in (delta)-Phase Plutonium Near the (delta)-(alpha)' Transition (open access)

Soft Phonons in (delta)-Phase Plutonium Near the (delta)-(alpha)' Transition

Plutonium and its alloys exhibit complex phase diagrams that imply anomalous lattice dynamics near phase stability boundaries. Specifically, the TA [111] phonon branch in Ga-stabilized {delta}-Pu at room temperature shows a pronounced soft mode at the zone boundary, which suggests a possible connection to the martensitic transformation from the fcc {delta}-phase to the monoclinic {alpha}{prime}-phase at low temperatures. This work is a study of the lattice dynamics of this system by x-ray thermal diffuse scattering. The results reveal little temperature dependence of the phonon frequencies, thus indicating that kinetic phonon softening is not responsible for this phase transition.
Date: September 13, 2007
Creator: Xu, R; Wong, J; Zshack, P; Hong, H & Chiang, T
Object Type: Article
System: The UNT Digital Library
Pulse Radiolysis of Aqueous Thiocyanate Solution (open access)

Pulse Radiolysis of Aqueous Thiocyanate Solution

The pulse radiolysis of N2O saturated aqueous solutions of KSCN was studied under neutral pH conditions. The observed optical absorption spectrum of the SCN• radical in solution is more complex than previously reported, but it is in good agreement with that measured in the gas phase. Kinetic traces at 330 nm and 472 nm corresponding to SCN• and (SCN)2•¯, respectively, were fit using a Monte Carlo simulation kinetic model. The rate coefficient for the oxidation of SCN¯ ions by OH radicals, an important reaction used in competition kinetics measurements, was found to be 1.4 ± 0.1 x 1010 M-1 s-1, about 30 % higher than the normally accepted value. A detailed discussion of the reaction mechanism is presented.
Date: January 13, 2005
Creator: Milosavljevic, Bratoljub H. & LaVerne, Jay A.
Object Type: Article
System: The UNT Digital Library
Towards a Sustainable Energy Balance: Progressive Efficiency and the Return of Energy Conservation (open access)

Towards a Sustainable Energy Balance: Progressive Efficiency and the Return of Energy Conservation

We argue that a primary focus on energy efficiency may not be sufficient to slow (and ultimately reverse) the growth in total energy consumption and carbon emissions. Instead, policy makers need to return to an earlier emphasis on"conservation," with energy efficiency seen as a means rather than an end in itself. We briefly review the concept of"intensive" versus"extensive" variables (i.e., energy efficiency versus energy consumption), and why attention to both consumption and efficiency is essential for effective policy in a carbon- and oil-constrained world with increasingly brittle energy markets. To start, energy indicators and policy evaluation metrics need to reflect energy consumption as well as efficiency. We introduce the concept of"progressive efficiency," with the expected or required level of efficiency varying as a function of house size, appliance capacity, or more generally, the scale of energy services. We propose introducing progressive efficiency criteria first in consumer information programs (including appliance labeling categories) and then in voluntary rating and recognition programs such as ENERGY STAR. As acceptance grows, the concept could be extended to utility rebates, tax incentives, and ultimately to mandatory codes and standards. For these and other programs, incorporating criteria for consumption as well as efficiency offers a path …
Date: August 13, 2007
Creator: Diamond, Rick; Harris, Jeff; Diamond, Rick; Iyer, Maithili; Payne, Christopher; Blumstein, Carl et al.
Object Type: Article
System: The UNT Digital Library
Radiological Survey Results for Areas A1 North, A5A, A6, and B2 at the Molycorp Washington Remediation Project, Washington, Pennsylvania (open access)

Radiological Survey Results for Areas A1 North, A5A, A6, and B2 at the Molycorp Washington Remediation Project, Washington, Pennsylvania

Perform radiological surveys of the Molycorp Washington Remediation Project (MWRP) facility in Washington, Pennsylvania
Date: March 13, 2007
Creator: Adams, W. C.
Object Type: Report
System: The UNT Digital Library
Waste Isolation Pilot Plant 2005 Site Environmental Report (open access)

Waste Isolation Pilot Plant 2005 Site Environmental Report

The purpose of this report is to provide information needed by the DOE to assess WIPP's environmental performance and to make WIPP environmental information available to stakeholders and members of the public. This report has been prepared in accordance with DOE Order 231.1A and DOE guidance. This report documents WIPP's environmental monitoring programs and their results for 2004. The WIPP Project is authorized by the DOE National Security and Military Applications of Nuclear Energy Authorization Act of 1980 (Pub. L. 96-164). After more than 20 years of scientific study and public input, WIPP received its first shipment of waste on March 26, 1999. Located in southeastern New Mexico, WIPP is the nation's first underground repository permitted to safely and permanently dispose of TRU radioactive and mixed waste (as defined in the WIPP LWA) generated through defense activities and programs. TRU waste is defined, in the WIPP LWA, as radioactive waste containing more than 100 nanocuries (3,700 becquerels [Bq]) of alpha-emitting TRU isotopes per gram of waste, with half-lives greater than 20 years except for high-level waste, waste that has been determined not to require the degree of isolation required by the disposal regulations, and waste the U.S. Nuclear Regulatory Commission …
Date: October 13, 2006
Creator: Services, Washington Regulatory and Environmental
Object Type: Report
System: The UNT Digital Library
Integrating automated shading and smart glazings with daylightcontrols (open access)

Integrating automated shading and smart glazings with daylightcontrols

None
Date: February 13, 2004
Creator: Selkowitz, Stephen & Lee, Eleanor
Object Type: Article
System: The UNT Digital Library
Avoiding the Haircut: Potential Ways to Enhance the Value of theUSDA's Section 9006 Program (open access)

Avoiding the Haircut: Potential Ways to Enhance the Value of theUSDA's Section 9006 Program

Section 9006 of Title IX of The Farm Security and Rural Investment Act of 2002 (the '2002 Farm Bill') established the Renewable Energy Systems and Energy Efficiency Improvements Program (the 'Section 9006 program'). Administered by the United States Department of Agriculture (USDA), the Section 9006 program provides grants, loan guarantees, and - perhaps in the future - direct loans to farmers, ranchers, and rural small businesses for assistance with purchasing renewable energy systems and making energy efficiency improvements. In the three rounds of Section 9006 funding to date (FY03-FY05), roughly 40% of all grant dollars in aggregate have been awarded to 'large' (defined as > 100 kW) wind projects. Such projects are also typically eligible for the Federal Production Tax Credit (PTC) codified in Section 45 of the US tax code. Because the PTC provides a significant amount of value to a wind project, most 'large wind' applicants to the Section 9006 program have also tried to take advantage of the PTC. Through what are known as 'anti-double-dipping' or, more colloquially, 'haircut' provisions, however, the size of the PTC is reduced if a project receives certain other forms of governmental support. Specifically, Section 45(b)(3) of the US tax code reduces …
Date: July 13, 2006
Creator: Bolinger, Mark
Object Type: Report
System: The UNT Digital Library
Soil Sampling Plan in Support of the Human Health and Ecological Risk Assessment for the Operation of the Explosives Waste Treatment Facilitiy at Site 300 of the Lawrence Livermore National Laboratory (open access)

Soil Sampling Plan in Support of the Human Health and Ecological Risk Assessment for the Operation of the Explosives Waste Treatment Facilitiy at Site 300 of the Lawrence Livermore National Laboratory

LLNL proposes to obtain soil samples from the following areas: (1) Four areas downwind of the Explosives Waste Treatment Facility (EWTF) Burn Units (i.e., Thermal Treatment Unit and Burn Pan); (2) One area upwind of the Burn Units and Detonation Pad; (3) Two areas downwind of the EWTF Detonation Pad; and (4) Three areas unaffected (representing ambient conditions) by EWTF operations approximately 7000-8000 feet upwind of the facility. The purpose of the sampling in areas 1, 2, and 3 is to detect if operations cause increases in concentrations of materials downwind of the Burn Units or downwind of the Detonation Pad. The purpose of the sampling in area 4 is to determine if previously developed background screening levels can be applied to EWTF operations. A 20 foot diameter circle will define each sample area. Soil samples will be obtained from four random locations inside each 20 foot circle. The samples will be obtained immediately below the surface, free of any organic matter (e.g., roots) and other surface and subsurface material (e.g., rocks) that is not conducive to analysis. The random identification of four discrete sample locations in each circle will allow the variability between sample locations and areas, if present, …
Date: December 13, 2007
Creator: Terusaki, S
Object Type: Report
System: The UNT Digital Library
Ion-Optics Calculations and Preliminary Precision Estimates of the Gas-Capable Ion Source for the 1-MV LLNL BioAMS Spectrometer (open access)

Ion-Optics Calculations and Preliminary Precision Estimates of the Gas-Capable Ion Source for the 1-MV LLNL BioAMS Spectrometer

Ion-optics calculations were performed for a new ion source and injection beam line. This source, which can accept both solid and gaseous targets, will be installed onto the 1-MV BioAMS spectrometer at the Center for Accelerator Mass Spectrometry, located at Lawrence Livermore National Laboratory and will augment the current LLNL cesium-sputter solid sample ion source. The ion source and its associated injection beam line were designed to allow direct quantification of {sup 14}C/{sup 12}C and {sup 3}H/{sup 1}H isotope ratios from both solid and gaseous targets without the need for isotope switching. Once installed, this source will enable the direct linking of a nanoflow LC system to the spectrometer to provide for high-throughput LC-AMS quantitation from a continuous flow. Calculations show that, for small samples, the sensitivity of the gas-accepting ion source could be precision limited but zeptomole quantitation should be feasible.
Date: December 13, 2005
Creator: Ognibene, T. J.; Bench, G.; Brown, T. A. & Vogel, J. S.
Object Type: Article
System: The UNT Digital Library
Multi-year search for a diffuse flxu of muon neutrinos with AMANDA-II (open access)

Multi-year search for a diffuse flxu of muon neutrinos with AMANDA-II

A search for TeV-PeV muon neutrinos from unresolved sources was performed on AMANDA-II data collected between 2000 and 2003 with an equivalent livetime of 807 days. This diffuse analysis sought to find an extraterrestrial neutrino flux from sources with non-thermal components. The signal is expected to have a harder spectrum than the atmospheric muon and neutrino backgrounds. Since no excess of events was seen in the data over the expected background, an upper limit of E{sup 2}{Phi}{sub 90%C.L.} < 7.4 x 10{sup -8} GeV cm{sup -2} s{sup -1} sr{sup -1} is placed on the diffuse flux of muon neutrinos with a {Phi} {proportional_to} E{sup -2} spectrum in the energy range 16 TeV to 2.5 PeV. This is currently the most sensitive {Phi} {proportional_to} E{sup -2} diffuse astrophysical neutrino limit. We also set upper limits for astrophysical and prompt neutrino models, all of which have spectra different than {Phi} {proportional_to} E{sup -2}.
Date: April 13, 2008
Creator: Collaboration, IceCube; Klein, Spencer; Achterberg, A. & Collaboration, IceCube
Object Type: Article
System: The UNT Digital Library
Performance Demonstration Program Plan for Analysis of Simulated Headspace Gases (open access)

Performance Demonstration Program Plan for Analysis of Simulated Headspace Gases

The Performance Demonstration Program (PDP) for headspace gases distributes blind audit samples in a gas matrix for analysis of volatile organic compounds (VOCs). Participating measurement facilities (i.e., fixed laboratories, mobile analysis systems, and on-line analytical systems) are located across the United States. Each sample distribution is termed a PDP cycle. These evaluation cycles provide an objective measure of the reliability of measurements performed for transuranic (TRU) waste characterization. The primary documents governing the conduct of the PDP are the Quality Assurance Program Document (QAPD) (DOE/CBFO-94-1012) and the Waste Isolation Pilot Plant (WIPP) Waste Analysis Plan (WAP) contained in the Hazardous Waste Facility Permit (NM4890139088-TSDF) issued by the New Mexico Environment Department (NMED). The WAP requires participation in the PDP; the PDP must comply with the QAPD and the WAP. This plan implements the general requirements of the QAPD and the applicable requirements of the WAP for the Headspace Gas (HSG) PDP. Participating measurement facilities analyze blind audit samples of simulated TRU waste package headspace gases according to the criteria set by this PDP Plan. Blind audit samples (hereafter referred to as PDP samples) are used as an independent means to assess each measurement facility’s compliance with the WAP quality assurance …
Date: November 13, 2007
Creator: Office, Carlsbad Field
Object Type: Report
System: The UNT Digital Library
The silicon microstrip sensors of the ATLAS semiconductor tracker (open access)

The silicon microstrip sensors of the ATLAS semiconductor tracker

This paper describes the AC-coupled, single-sided, p-in-n silicon microstrip sensors used in the Semiconductor Tracker (SCT) of the ATLAS experiment at the CERN Large Hadron Collider (LHC). The sensor requirements, specifications and designs are discussed, together with the qualification and quality assurance procedures adopted for their production. The measured sensor performance is presented, both initially and after irradiation to the fluence anticipated after 10 years of LHC operation. The sensors are now successfully assembled within the detecting modules of the SCT, and the SCT tracker is completed and integrated within the ATLAS Inner Detector. Hamamatsu Photonics Ltd. supplied 92.2percent of the 15,392 installed sensors, with the remainder supplied by CiS.
Date: April 13, 2007
Creator: Collaboration, ATLAS SCT & Spieler, Helmuth G.
Object Type: Article
System: The UNT Digital Library
SATB1 tethers multiple gene loci to reprogram expression profiledriving breast cancer metastasis (open access)

SATB1 tethers multiple gene loci to reprogram expression profiledriving breast cancer metastasis

Global changes in gene expression occur during tumor progression, as indicated by expression profiling of metastatic tumors. How this occurs is poorly understood. SATB1 functions as a genome organizer by folding chromatin via tethering multiple genomic loci and recruiting chromatin remodeling enzymes to regulate chromatin structure and expression of a large number of genes. Here we show that SATB1 is expressed at high levels in aggressive breast cancer cells, and is undetectable in non-malignant breast epithelial cells. Importantly, RNAi-mediated removal of SATB1 from highly-aggressive MDA-MB-231 cells altered the expression levels of over 1200 genes, restored breast-like acinar polarity in three-dimensional cultures, and prevented the metastastic phenotype in vivo. Conversely, overexpression of SATB1 in the less-aggressive breast cancer cell line Hs578T altered the gene expression profile and increased metastasis dramatically in vivo. Thus, SATB1 is a global regulator of gene expression in breast cancer cells, directly regulating crucial metastasis-associated genes, including ERRB2 (HER2/NEU), TGF-{beta}1, matrix metalloproteinase 3, and metastasin. The identification of SATB1 as a protein that re-programs chromatin organization and transcription profiles to promote breast cancer metastasis suggests a new model for metastasis and may provide means of therapeutic intervention.
Date: July 13, 2006
Creator: Han, Hye-Jung; Kohwi, Yoshinori & Kohwi-Shigematsu, Terumi
Object Type: Article
System: The UNT Digital Library
Toward Fast Computation of Dense Image Correspondence on the GPU (open access)

Toward Fast Computation of Dense Image Correspondence on the GPU

Large-scale video processing systems are needed to support human analysis of massive collections of image streams. Video, from both current small-format and future large-format camera systems, constitutes the single largest data source of the near future, dwarfing the output of all other data sources combined. A critical component to further advances in the processing and analysis of such video streams is the ability to register successive video frames into a common coordinate system at the pixel level. This capability enables further downstream processing, such as background/mover segmentation, 3D model extraction, and compression. We present here our recent work on computing these correspondences. We employ coarse-to-fine hierarchical approach, matching pixels from the domain of a source image to the domain of a target image at successively higher resolutions. Our diamond-style image hierarchy, with total pixel counts increasing by only a factor of two at each level, improves the prediction quality as we advance from level to level, and reduces potential grid artifacts in the results. We demonstrate the quality our approach on real aerial city imagery. We find that registration accuracy is generally on the order of one quarter of a pixel. We also benchmark the fundamental processing kernels on the …
Date: August 13, 2007
Creator: Duchaineau, M; Cohen, J & Vaidya, S
Object Type: Article
System: The UNT Digital Library
Transmission Electron Microscopy Study of InN Nanorods (open access)

Transmission Electron Microscopy Study of InN Nanorods

InN nanorods were grown on a, c-, and r-plane of sapphire and also on Si (111) and GaN (0001) by non-catalytic, template-free hydride metal-organic vapor phase epitaxy and studied by transmission electron microscopy, electron energy loss (EELS) and photoluminescence (PL) at room temperature. These nanocrystals have different shapes and different faceting depending on the substrate used and their crystallographic orientation. EELS measurements have confirmed the high purity of these crystals. The observed PL peak was in the range of 0.9-0.95 eV. The strongest PL intensity was observed for the nanocrystals with the larger diameters.
Date: July 13, 2006
Creator: Liliental-Weber, Z.; Li, X.; Kryliouk, Olga; Park, H.J.; Mangum,J. & Anderson, T.
Object Type: Article
System: The UNT Digital Library
Radiation monitoring with CVD Diamonds and PIN Diodes at BaBar (open access)

Radiation monitoring with CVD Diamonds and PIN Diodes at BaBar

The BaBar experiment at the Stanford Linear Accelerator Center has been using two polycrystalline chemical vapor deposition (pCVD) diamonds and 12 silicon PIN diodes for radiation monitoring and protection of the Silicon Vertex Tracker (SVT). We have used the pCVD diamonds for more than 3 years, and the PIN diodes for 7 years. We will describe the SVT and SVT radiation monitoring system as well as the operational difficulties and radiation damage effects on the PIN diodes and pCVD diamonds in a high-energy physics environment.
Date: February 13, 2008
Creator: Bruinsma, M.; Burchat, P.; Curry, S.; Edwards, A.J.; Kagan, H.; Kass, R. et al.
Object Type: Article
System: The UNT Digital Library
Hyperfine Quenching of the 2s2p 3P0 State of Berylliumlike Ions (open access)

Hyperfine Quenching of the 2s2p 3P0 State of Berylliumlike Ions

The hyperfine-induced 2s2p {sup 3}P{sub 0}-2s{sup 2} {sup 1}S{sub 0} transition rate for Be-like {sup 47}Ti{sup 18+} was recently measured in a storage-ring experiment by Schippers et al. [Phys. Rev. Lett. 98, 033001 (2007)]. The measured value of 0.56(3) s{sup -1} is almost 60% larger than the theoretical value of 0.356 s{sup -1} from a multiconfiguration Dirac-Fock calculation by Marques et al. [Phys. Rev. A 47, 929 (1993)]. In this work, we use a large-scale relativistic configuration-interaction method to calculate these hyperfine-induced rates for ions with Z = 6-92. Coherent hyperfine-quenching effects between the 2s2p {sup 1,3}P{sub 1} states are included in a perturbative as well as a radiation damping approach. Contrary to the claims of Marques et al., contributions from the {sup 1}P{sub 1} state are substantial and lead to a hyperfine-induced rate of 0.67 s{sup -1}, in better agreement with, though larger than, the measured value.
Date: March 13, 2008
Creator: Cheng, K T; Chen, M H & Johnson, W R
Object Type: Article
System: The UNT Digital Library
Spatiotemporal variations in growing season exchanges of CO2, H2O,and sensible heat in agricultural fields of the Southern GreatPlains (open access)

Spatiotemporal variations in growing season exchanges of CO2, H2O,and sensible heat in agricultural fields of the Southern GreatPlains

Climate, vegetation cover, and management create fine-scaleheterogeneity in unirrigated agricultural regions, with important but notwell-quantified consequences for spatial and temporal variations insurface CO2, water, and heat fluxes. We measured eddy covariance fluxesin seven agricultural fields--comprising winter wheat, pasture, andsorghum--in the U.S. Southern Great Plains (SGP) during the 2001-2003growing seasons. Land-cover was the dominant source of variation insurface fluxes, with 50-100 percent differences between fields planted inwinter-spring versus fields planted in summer. Interannual variation wasdriven mainly by precipitation, which varied more than two-fold betweenyears. Peak aboveground biomass and growing-season net ecosystem exchange(NEE) of CO2 increased in rough proportion to precipitation. Based on apartitioning of gross fluxes with a regression model, ecosystemrespiration increased linearly with gross primary production, but with anoffset that increased near the time of seed production. Because theregression model was designed for well-watered periods, it successfullyretrieved NEE and ecosystem parameters during the peak growing season,and identified periods of moisture limitation during the summer. Insummary, the effects of crop type, land management, and water limitationon carbon, water, and energy fluxes were large. Capturing the controllingfactors in landscape scale models will be necessary to estimate theecological feedbacks to climate and other environmental impactsassociated with changing human needs for agricultural production of …
Date: June 13, 2007
Creator: Fischer, Marc L.; Billesbach, David P.; Berry, Joseph A.; Riley,William J. & Torn, Margaret S.
Object Type: Article
System: The UNT Digital Library
MARKOV Model Application to Proliferation Risk Reduction of an Advanced Nuclear System (open access)

MARKOV Model Application to Proliferation Risk Reduction of an Advanced Nuclear System

The Generation IV International Forum (GIF) emphasizes proliferation resistance and physical protection (PR&PP) as a main goal for future nuclear energy systems. The GIF PR&PP Working Group has developed a methodology for the evaluation of these systems. As an application of the methodology, Markov model has been developed for the evaluation of proliferation resistance and is demonstrated for a hypothetical Example Sodium Fast Reactor (ESFR) system. This paper presents the case of diversion by the facility owner/operator to obtain material that could be used in a nuclear weapon. The Markov model is applied to evaluate material diversion strategies. The following features of the Markov model are presented here: (1) An effective detection rate has been introduced to account for the implementation of multiple safeguards approaches at a given strategic point; (2) Technical failure to divert material is modeled as intrinsic barriers related to the design of the facility or the properties of the material in the facility; and (3) Concealment to defeat or degrade the performance of safeguards is recognized in the Markov model. Three proliferation risk measures are calculated directly by the Markov model: the detection probability, technical failure probability, and proliferation time. The material type is indicated by …
Date: July 13, 2008
Creator: Bari, R. A.
Object Type: Article
System: The UNT Digital Library