A Historical Profile of the Higgs Boson (open access)

A Historical Profile of the Higgs Boson

The Higgs boson was postulated in 1964, and phenomenological studies of its possible production and decays started in the early 1970s, followed by studies of its possible productionin e{sup +} e{sup -}, {anti p}p and pp collisions, in particular. Until recently, the most sensitive searches for the Higgs boson were at LEP between 1989 and 2000, which have been complemented bysearches at the Fermilab Tevatron. The LHC has recently entered the hunt, excluding a Higgs boson over a large range of masses and revealing a tantalizing hint in the range 119 to125 GeV, and there are good prospects that the existence or otherwise of the Higgs boson will soon be established. One of the most attractive possibilities is that the Higgs bosonis accompanied by supersymmetry, though composite options have yet to be excluded. This article reviews some of the key historical developments in Higgs physics over the past half-century.
Date: January 31, 2012
Creator: Ellis, John; Gaillard, Mary K. & Nanopoulos, Dimitri V.
System: The UNT Digital Library
Multi-core and Many-core Shared-memory Parallel Raycasting Volume Rendering Optimization and Tuning (open access)

Multi-core and Many-core Shared-memory Parallel Raycasting Volume Rendering Optimization and Tuning

Given the computing industry trend of increasing processing capacity by adding more cores to a chip, the focus of this work is tuning the performance of a staple visualization algorithm, raycasting volume rendering, for shared-memory parallelism on multi-core CPUs and many-core GPUs. Our approach is to vary tunable algorithmic settings, along with known algorithmic optimizations and two different memory layouts, and measure performance in terms of absolute runtime and L2 memory cache misses. Our results indicate there is a wide variation in runtime performance on all platforms, as much as 254% for the tunable parameters we test on multi-core CPUs and 265% on many-core GPUs, and the optimal configurations vary across platforms, often in a non-obvious way. For example, our results indicate the optimal configurations on the GPU occur at a crossover point between those that maintain good cache utilization and those that saturate computational throughput. This result is likely to be extremely difficult to predict with an empirical performance model for this particular algorithm because it has an unstructured memory access pattern that varies locally for individual rays and globally for the selected viewpoint. Our results also show that optimal parameters on modern architectures are markedly different from those …
Date: January 31, 2012
Creator: Howison, Mark
System: The UNT Digital Library
ADVANCES IN HEXAVALENT CHROMIUM REMOVAL AT HANFORD (open access)

ADVANCES IN HEXAVALENT CHROMIUM REMOVAL AT HANFORD

At the Hanford Site, chromium was used as a corrosion inhibitor in the reactor cooling water and was introduced into the groundwater as a result of planned and unplanned discharges from reactors during plutonium production since 1944. Beginning in 1995, groundwater treatment methods were evaluated leading to the use of pump and treat facilities with ion exchange using Dowex 21 K, a regenerable strong base anion exchange resin. This required regeneration of the resin, which is currently performed offsite. Resin was installed in a 4 vessel train, with resin removal required from the lead vessel approximately once a month. In 2007, there were 8 trains (32 vessels) in operation. In 2008, DOE recognized that regulatory agreements would require significant expansion in the groundwater chromium treatment capacity. Previous experience from one of the DOE project managers led to identification of a possible alternative resin, and the contractor was requested to evaluate alternative resins for both cost and programmatic risk reductions. Testing was performed onsite in 2009 and 2010, using a variety of potential resins in two separate facilities with groundwater from specific remediation sites to demonstrate resin performance in the specific groundwater chemistry at each site. The testing demonstrated that a …
Date: January 30, 2012
Creator: Neshem, D. O. & Riddelle, J.
System: The UNT Digital Library
DEVELOPMENT AND DEPLOYMENT OF THE MOBILE ARM RETRIEVAL SYSTEM (MARS) - 12187 (open access)

DEVELOPMENT AND DEPLOYMENT OF THE MOBILE ARM RETRIEVAL SYSTEM (MARS) - 12187

Washington River Protection Solutions (WRPS) is developing and deploying Mobile Arm Retrieval System (MARS) technologies solutions to support retrieval of radioactive and chemical waste from underground single shell storage tanks (SST) located at the Hanford Site, which is near Richland, Washington. WRPS has developed the MARS using a standardized platform that is capable of deploying multiple retrieval technologies. To date, WRPS, working with their mentor-protege company, Columbia Energy and Environmental Services (CEES), has developed two retrieval mechanisms, MARS-Sluicing (MARS-S) and MARS-Vacuum (MARS-V). MARS-S uses pressurized fluids routed through spray nozzles to mobilize waste materials to a centrally located slurry pump (deployed in 2011). MARS-V uses pressurized fluids routed through an eductor nozzle. The eductor nozzle allows a vacuum to be drawn on the waste materials. The vacuum allows the waste materials to be moved to an in-tank vessel, then extracted from the SST and subsequently pumped to newer and safer double shell tanks (DST) for storage until the waste is treated for disposal. The MARS-S system is targeted for sound SSTs (i.e., non leaking tanks). The MARS-V is targeted for assumed leaking tanks or those tanks that are of questionable integrity. Both versions of MARS are being/have been developed in …
Date: January 30, 2012
Creator: CA, BURKE; MR, LANDON & CE, HANSON
System: The UNT Digital Library
Modeling and Generating New Flexure Constraint Elements (open access)

Modeling and Generating New Flexure Constraint Elements

None
Date: January 30, 2012
Creator: Hopkins, J B
System: The UNT Digital Library
AN OVERVIEW OF TOOL FOR RESPONSE ACTION COST ESTIMATING (TRACE) (open access)

AN OVERVIEW OF TOOL FOR RESPONSE ACTION COST ESTIMATING (TRACE)

Tools and techniques that provide improved performance and reduced costs are important to government programs, particularly in current times. An opportunity for improvement was identified for preparation of cost estimates used to support the evaluation of response action alternatives. As a result, CH2M HILL Plateau Remediation Company has developed Tool for Response Action Cost Estimating (TRACE). TRACE is a multi-page Microsoft Excel{reg_sign} workbook developed to introduce efficiencies into the timely and consistent production of cost estimates for response action alternatives. This tool combines costs derived from extensive site-specific runs of commercially available remediation cost models with site-specific and estimator-researched and derived costs, providing the best estimating sources available. TRACE also provides for common quantity and key parameter links across multiple alternatives, maximizing ease of updating estimates and performing sensitivity analyses, and ensuring consistency.
Date: January 30, 2012
Creator: Ferries, Steven R.; Klink, Kevin L. & Ostapkowicz, Bradley
System: The UNT Digital Library
SOIL DESICCATION TECHNIQUES STRATEGIES FOR IMMOBILIZATION OF DEEP VADOSE CONTAMINANTS AT THE HANFORD CENTRAL PLATEAU (open access)

SOIL DESICCATION TECHNIQUES STRATEGIES FOR IMMOBILIZATION OF DEEP VADOSE CONTAMINANTS AT THE HANFORD CENTRAL PLATEAU

Deep vadose zone contamination poses some of the most difficult remediation challenges for the protection of groundwater at the Hanford Site where processes and technologies are being developed and tested for use in the on-going effort to remediate mobile contamination in the deep vadose zone, the area deep beneath the surface. Historically, contaminants were discharged to the soil along with significant amounts of water, which continues to drive contaminants deeper in the vadose zone toward groundwater. Soil desiccation is a potential in situ remedial technology well suited for the arid conditions and the thick vadose zone at the Hanford Site. Desiccation techniques could reduce the advance of contaminants by removing the pore water to slow the rate of contaminants movement toward groundwater. Desiccation technologies have the potential to halt or slow the advance of contaminants in unsaturated systems, as well as aid in reduction of contaminants from these same areas. Besides reducing the water flux, desiccation also establishes capillary breaks that would require extensive rewetting to resume pore water transport. More importantly, these techniques have widespread application, whether the need is to isolate radio nuclides or address chemical contaminant issues. Three different desiccation techniques are currently being studied at Hanford.
Date: January 30, 2012
Creator: MW, BENECKE; GB, CHRONISTER & MJ, TRUEX
System: The UNT Digital Library
Study of CO2 Absorption and Negative Ion Formation during Direct Ionization of CO2 with a Cs+ Beam (open access)

Study of CO2 Absorption and Negative Ion Formation during Direct Ionization of CO2 with a Cs+ Beam

None
Date: January 30, 2012
Creator: Salazar, G & Ognibene, T
System: The UNT Digital Library
The Successful Utilization of Commercial Treatment Capabilities to Disposition Hanford's No-Path-Forward, Suspect Transuranic Wastes (open access)

The Successful Utilization of Commercial Treatment Capabilities to Disposition Hanford's No-Path-Forward, Suspect Transuranic Wastes

The U.S. Department of Energy (DOE) Richland Operations Office (RL) has adopted the 2015 Vision for Cleanup of the Hanford Site. The CH2M HILL Plateau Remediation Company's (CHPRC) Waste and Fuels Management Project (W&FMP) and their partners support this mission by providing centralized waste management services for the Hanford Site waste generating organizations. At the time of the CHPRC contract award (August 2008) slightly more than 9,000 cubic meters (m{sup 3}) of legacy waste was defined as ''no-path-forward waste.'' A significant portion of this waste (7,650 m{sup 3}) comprised wastes with up to 50 grams of special nuclear materials (SNM) in oversized packages recovered during retrieval operations and large glove boxes removed from Hanford's Plutonium Finishing Plant (PFP). Through a collaborative effort between the DOE, CHPRC, and Perma-Fix Environmental Services, Inc. (PESI), pathways for these problematic wastes were developed and are currently being implemented.
Date: January 30, 2012
Creator: Blackford, L. T.; Catlow, R. L.; West, L. D.; Collins, M. S.; Romine, L. D. & Moak, D. J.
System: The UNT Digital Library
Fireside Corrosion (open access)

Fireside Corrosion

None
Date: January 27, 2012
Creator: Holcomb, Gordon R.
System: The UNT Digital Library
Interactive Visualizations for Performance Analysis of Heterogeneous Computing Clusters (open access)

Interactive Visualizations for Performance Analysis of Heterogeneous Computing Clusters

None
Date: January 27, 2012
Creator: Landge, A; Levine, J; Bremer, P; Schulz, M; Gamblin, T; Bhatele, A et al.
System: The UNT Digital Library
FULL SCALE TESTING TECHNOLOGY MATURATION OF A THIN FILM EVAPORATOR FOR HIGH-LEVEL LIQUID WASTE MANAGEMENT AT HANFORD - 12125 (open access)

FULL SCALE TESTING TECHNOLOGY MATURATION OF A THIN FILM EVAPORATOR FOR HIGH-LEVEL LIQUID WASTE MANAGEMENT AT HANFORD - 12125

Simulant testing of a full-scale thin-film evaporator system was conducted in 2011 for technology development at the Hanford tank farms. Test results met objectives of water removal rate, effluent quality, and operational evaluation. Dilute tank waste simulant, representing a typical double-shell tank supernatant liquid layer, was concentrated from a 1.1 specific gravity to approximately 1.5 using a 4.6 m{sup 2} (50 ft{sup 2}) heated transfer area Rototherm{reg_sign} evaporator from Artisan Industries. The condensed evaporator vapor stream was collected and sampled validating efficient separation of the water. An overall decontamination factor of 1.2E+06 was achieved demonstrating excellent retention of key radioactive species within the concentrated liquid stream. The evaporator system was supported by a modular steam supply, chiller, and control computer systems which would be typically implemented at the tank farms. Operation of these support systems demonstrated successful integration while identifying areas for efficiency improvement. Overall testing effort increased the maturation of this technology to support final deployment design and continued project implementation.
Date: January 26, 2012
Creator: AR, TEDESCHI; JE, CORBETT; RA, WILSON & J, LARKIN
System: The UNT Digital Library
HANFORD RIVER PROTECTION PROJECT ENHANCED MISSION PLANNING THROUGH INNOVATIVE TOOLS LIFECYCLE COST MODELING AND AQUEOUS THERMODYNAMIC MODELING - 12134 (open access)

HANFORD RIVER PROTECTION PROJECT ENHANCED MISSION PLANNING THROUGH INNOVATIVE TOOLS LIFECYCLE COST MODELING AND AQUEOUS THERMODYNAMIC MODELING - 12134

Two notable modeling efforts within the Hanford Tank Waste Operations Simulator (HTWOS) are currently underway to (1) increase the robustness of the underlying chemistry approximations through the development and implementation of an aqueous thermodynamic model, and (2) add enhanced planning capabilities to the HTWOS model through development and incorporation of the lifecycle cost model (LCM). Since even seemingly small changes in apparent waste composition or treatment parameters can result in large changes in quantities of high-level waste (HLW) and low-activity waste (LAW) glass, mission duration or lifecycle cost, a solubility model that more accurately depicts the phases and concentrations of constituents in tank waste is required. The LCM enables evaluation of the interactions of proposed changes on lifecycle mission costs, which is critical for decision makers.
Date: January 26, 2012
Creator: KL, PIERSON & FL, MEINERT
System: The UNT Digital Library
Ionization of Water Clusters is Mediated by Exciton Energy Transfer from Argon Clusters (open access)

Ionization of Water Clusters is Mediated by Exciton Energy Transfer from Argon Clusters

The exciton energy deposited in an argon cluster, (Arn ,< n=20>) using VUV radiation is transferred to softly ionize doped water clusters, ((H2O)n, n=1-9) leading to the formation of non-fragmented clusters. Following the initial excitation, electronic energy is channeled to ionize the doped water cluster while evaporating the Ar shell, allowing identification of fragmented and complete water cluster ions. Examination of the photoionization efficiency curve shows that cluster evaporation from excitons located above 12.6 eV are not enough to cool the energized water cluster ion, and leads to their dissociation to (H2O)n-2H+ (protonated) clusters.
Date: January 25, 2012
Creator: Golan, Amir & Ahmed, Musahid
System: The UNT Digital Library
OVERVIEW OF ENHANCED HANFORD SINGLE-SHELL TANK (SST) INTEGRITY PROJECT - 12128 (open access)

OVERVIEW OF ENHANCED HANFORD SINGLE-SHELL TANK (SST) INTEGRITY PROJECT - 12128

To improve the understanding of the single-shell tanks integrity, Washington River Protection Solutions, LLC, the USDOE Hanford Site tank contractor, developed an enhanced Single-Shell Tank (SST) Integrity Project in 2009. An expert panel on SST integrity, consisting of various subject matters experts in industry and academia, was created to provide recommendations supporting the development of the project. This panel developed 33 recommendations in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration, Seventeen of these recommendations were used to develop the basis for the M-45-10-1 Change Package for the Hanford Federal Agreement and Compliance Order, which is also known as the Tri-Party Agreement. The change package identified two phases of work for SST integrity. The initial phase has been focused on efforts to envelope the integrity of the tanks. The initial phase was divided into two primary areas of investigation: structural integrity and leak integrity. If necessary based on the outcome from the initial work, a second phase would be focused on further definition of the integrity of the concrete and liners. Combined these two phases are designed to support the formal integrity assessment of the Hanford SSTs in 2018 by …
Date: January 25, 2012
Creator: Venetz, T. J.; Boomer, K. D.; Washenfelder, D. J. & Johnson, J. B.
System: The UNT Digital Library
OVERVIEW OF HANFORD SINGLE SHELL TANK (SST) STRUCTURAL INTEGRITY - 12123 (open access)

OVERVIEW OF HANFORD SINGLE SHELL TANK (SST) STRUCTURAL INTEGRITY - 12123

To improve the understanding of the single-shell tanks (SSTs) integrity, Washington River Protection Solutions, LLC (WRPS), the USDOE Hanford Site tank contractor, developed an enhanced Single-Shell Tank Integrity Project in 2009. An expert panel on SST integrity, consisting of various subject matters experts in industry and academia, was created to provide recommendations supporting the development of the project. This panel developed 33 recommendations in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration. Seventeen of these recommendations were used to develop the basis for the M-45-10-1 Change Package for the Hanford Federal Agreement and Compliance Order, which is also known as the Tri-Party Agreement. The structural integrity of the tanks is a key element in completing the cleanup mission at the Hanford Site. There are eight primary recommendations related to the structural integrity of Hanford SSTs. Six recommendations are being implemented through current and planned activities. The structural integrity of the Hanford SSTs is being evaluated through analysis, monitoring, inspection, materials testing, and construction document review. Structural evaluation in the form of analysis is performed using modern finite element models generated in ANSYS{reg_sign} The analyses consider in-situ, thermal, operating loads and …
Date: January 25, 2012
Creator: Rast, R. S.; Rinker, M. W.; Washenfelder, D. J. & Johnson, J. B.
System: The UNT Digital Library
SINGLE-SHELL TANKS LEAK INTEGRITY ELEMENTS/SX FARM LEAK CAUSES AND LOCATIONS - 12127 (open access)

SINGLE-SHELL TANKS LEAK INTEGRITY ELEMENTS/SX FARM LEAK CAUSES AND LOCATIONS - 12127

Washington River Protection Solutions, LLC (WRPS) developed an enhanced single-shell tank (SST) integrity project in 2009. An expert panel on SST integrity was created to provide recommendations supporting the development of the project. One primary recommendation was to expand the leak assessment reports (substitute report or LD-1) to include leak causes and locations. The recommendation has been included in the M-045-9IF Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) as one of four targets relating to SST leak integrity. The 241-SX Farm (SX Farm) tanks with leak losses were addressed on an individual tank basis as part of LD-1. Currently, 8 out of 23 SSTs that have been reported to having a liner leak are located in SX Farm. This percentage was the highest compared to other tank farms which is why SX Farm was analyzed first. The SX Farm is comprised of fifteen SSTs built 1953-1954. The tanks are arranged in rows of three tanks each, forming a cascade. Each of the SX Farm tanks has a nominal I-million-gal storage capacity. Of the fifteen tanks in SX Farm, an assessment reported leak losses for the following tanks: 241-SX-107, 241-SX-108, 241-SX-109, 241-SX-111, 241-SX-112, 241-SX-113, 241-SX-114 and 241-SX-115. The method …
Date: January 25, 2012
Creator: TJ, VENETZ; D, WASHENFELDER; J, JOHNSON & C, GIRARDOT
System: The UNT Digital Library
Conformal growth of Mo/Si multilayers on grating substrates using collimated ion beam sputtering (open access)

Conformal growth of Mo/Si multilayers on grating substrates using collimated ion beam sputtering

Deposition of multilayers on saw-tooth substrates is a key step in the fabrication of multilayer blazed gratings (MBG) for extreme ultraviolet and soft x-rays. Growth of the multilayers can be perturbed by shadowing effects caused by the highly corrugated surface of the substrates, which results in distortion of the multilayer stack structure and degradation of performance of MBGs. To minimize the shadowing effects we used an ionbeam sputtering machine with a highly collimated atomic flux to deposit Mo/Si multilayers on saw-tooth substrates. The sputtering conditions were optimized by finding a balance between smoothening and roughening processes in order to minimize degradation of the groove profile in the course of deposition and at the same time to keep the interfaces of a multilayer stack smooth enough for high efficiency. An optimal value of energy of 200 eV for sputtering Kr{sup +} ions was found by deposition of test multilayers on flat substrates at a range of ion energies. Two saw-tooth substrates were deposited at energies of 200 eV and 700 eV for the sputtering ions. It was found that reduction of the ion energy improved the blazing performance of the MBG and resulted in a 40% gain in the diffraction efficiency …
Date: January 23, 2012
Creator: Gawlitza, Peter; Cambie, Rossana; Dhuey, Scott; Gullikson, Eric; Warwick, Tony; Braun, Stefan et al.
System: The UNT Digital Library
Measurement of the Double-Beta Decay Half-life of {sup 136}Xe in KamLAND-Zen (open access)

Measurement of the Double-Beta Decay Half-life of {sup 136}Xe in KamLAND-Zen

We present results from the KamLAND-Zen double-beta decay experiment based on an exposure of 77.6 days with 129 kg of {sup 136}Xe. The measured two-neutrino double-beta decay half-life of {sup 136}Xe is T{sup 2{nu}}{sub 1/2} = 2:38 {+-}#6; 0:02(stat)#6;{+-}0.14(syst)#2;x10{sup 21} yr, consistent with a recent measurement by EXO-200. We also obtain a lower limit for the neutrinoless double-beta decay half-life, T{sup 0{nu}}{sub 1/2} > 5.7 x#2; 10{sup 24} yr at 90% C.L.
Date: January 23, 2012
Creator: Collaboration, KamLAND-Zen; Gando, A.; Gando, Y.; Hanakago, H.; Ikeda, H.; Inoue, K. et al.
System: The UNT Digital Library
PERFORMANCE ASSESSMENT ASSISTANCE ACTIVITIES IN THE DOE COMPLEX (open access)

PERFORMANCE ASSESSMENT ASSISTANCE ACTIVITIES IN THE DOE COMPLEX

The United States Department of Energy Office of Environmental Management (DOE-EM) has established a Performance Assessment Community of Practice (PA CoP) to foster the sharing of information among performance assessment (PA) and risk assessment practitioners, regulators and oversight personnel. The general intent is to contribute to continuous improvement in the consistency, technical adequacy and quality of implementation of PAs and risk assessments around the DOE Complex. The PA CoP activities have involved commercial disposal facilities and international participants to provide a global perspective. The PA CoP has also sponsored annual technical exchanges as a means to foster improved communication and to share lessons learned from on-going modelling activities. The PA CoP encourages activities to provide programmatic and technical assistance in the form of sharing experience and lessons learned with practitioners during the development of PAs and risk assessments. This assistance complements DOE-EM reviews through the Low-Level Waste Disposal Facility Federal Review Group (LFRG) that are conducted after modelling efforts are completed. Such up-front assistance is providing additional value in terms of improving consistency and sharing of information. There has been a substantial increase in the amount of assistance being provided. The assistance has been well received by practitioners and regulators …
Date: January 23, 2012
Creator: Seitz, R.
System: The UNT Digital Library
Ultra-high efficiency multilayer blazed gratings through deposition kinetic control (open access)

Ultra-high efficiency multilayer blazed gratings through deposition kinetic control

Diffraction efficiency of multilayer coated blazed gratings (MBG) strongly depends on the perfection of the saw-toothshaped layers in the overall composite structure. Growth of multilayers on saw-tooth substrates should be carefully optimized in order to reduce groove profile distortion and at the same time to avoid significant roughening of multilayer interfaces. In this work we report on a new way to optimize growth of sputter-deposited Mo/Si multilayers on saw-tooth substrates through variation of the sputtering gas pressure. A new record for diffraction efficiency of 44% was achieved for a optimized MBG with groove density of 5250 lines/mm at the wavelength of 13.1 nm.
Date: January 23, 2012
Creator: Anderson, Erik; Gullikson, Eric; Salmassi, Farhad; Warwick, Tony; Yashchuk, Valeriy & Padmore, Howard
System: The UNT Digital Library
A Green Prison: The Santa Rita Jail Campus Microgrid (open access)

A Green Prison: The Santa Rita Jail Campus Microgrid

A large microgrid project is nearing completion at Alameda County’s twenty-two-year-old 45 ha 4,000-inmate Santa Rita Jail, about 70 km east of San Francisco. Often described as a green prison, it has a considerable installed base of distributed energy resources (DER) including an eight-year old 1.2 MW PV array, a five-year old 1 MW fuel cell with heat recovery, and considerable efficiency investments. A current US$14 M expansion adds a 2 MW-4 MWh Li-ion battery, a static disconnect switch, and various controls upgrades. During grid blackouts, or when conditions favor it, the Jail can now disconnect from the grid and operate as an island, using the on-site resources described together with its back-up diesel generators. In other words, the Santa Rita Jail is a true microgrid, or μgrid, because it fills both requirements, i.e. it is a locally controlled system, and it can operate both grid connected and islanded. The battery’s electronics includes Consortium for Electric Reliability Technology (CERTS) Microgrid technology. This enables the battery to maintain energy balance using droops without need for a fast control system.
Date: January 22, 2012
Creator: Marnay, Chris; DeForest, Nicholas & Lai, Judy
System: The UNT Digital Library
Reconstruction Algorithm for Point Source Neutron Imaging through Finite Thickness Scintillator (open access)

Reconstruction Algorithm for Point Source Neutron Imaging through Finite Thickness Scintillator

None
Date: January 22, 2012
Creator: Wang, H; Tang, V; McCarrick, J F & Moran, S
System: The UNT Digital Library
Grain-Scale Failure in Thermal Spallation Drilling (open access)

Grain-Scale Failure in Thermal Spallation Drilling

Geothermal power promises clean, renewable, reliable and potentially widely-available energy, but is limited by high initial capital costs. New drilling technologies are required to make geothermal power financially competitive with other energy sources. One potential solution is offered by Thermal Spallation Drilling (TSD) - a novel drilling technique in which small particles (spalls) are released from the rock surface by rapid heating. While TSD has the potential to improve drilling rates of brittle granitic rocks, the coupled thermomechanical processes involved in TSD are poorly described, making system control and optimization difficult for this drilling technology. In this paper, we discuss results from a new modeling effort investigating thermal spallation drilling. In particular, we describe an explicit model that simulates the grain-scale mechanics of thermal spallation and use this model to examine existing theories concerning spalling mechanisms. We will report how borehole conditions influence spall production, and discuss implications for macro-scale models of drilling systems.
Date: January 19, 2012
Creator: Walsh, Stuart C.; Lomov, Ilya & Roberts, Jeffery J.
System: The UNT Digital Library