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Accelerator-Based Irradiation Creep of Pyrolytic Carbon Used in TRISO Fuel Particles for the (VHTR) Very Hight Temperature Reactors

Description: Pyrolytic carbon (PyC) is one of the important structural materials in the TRISO fuel particles which will be used in the next generation of gas-cooled very-high-temperature reactors (VHTR). When the TRISO particles are under irradiation at high temperatures, creep of the PyC layers may cause radial cracking leading to catastrophic particle failure. Therefore, a fundamental understanding of the creep behavior of PyC during irradiation is required to predict the overall fuel performance.
Date: July 30, 2010
Creator: Wang, Lumin & Was, Gary
Partner: UNT Libraries Government Documents Department

Scanning tunneling microscopy and atomic force microscopy of Au implanted in highly ordered pyrolytic graphite

Description: Surfaces of highly oriented pyrolytic graphite implanted with gold were studied by both constant current STM, constant force, and tapping mode AFM. Gold colloids were observed by both constant current STM and tapping mode AFM. The surfaces can be modified by applying currents of {plus_minus}4 V and 1 nA. In addition, pyramidal and faceted structures were observed on sample surfaces suggesting the presence of diamond microcrystals.
Date: January 1, 1996
Creator: Tung, Y.S.; Ueda, A.; Henderson, D.O.; Mu, R.; Gu, Z.; White, C.W. et al.
Partner: UNT Libraries Government Documents Department

Comparison of the electrochemical properties of several commercial graphites with a templated disordered carbon

Description: A templated carbon was prepared by the pyrolysis of pyrene impregnated into pillared clay (PILC). The electrochemical performance of this was evaluated with the goal of using this material as an anode in Li-ion cells. The reversible capacity was measured as a function of C rate and the cycling characteristics were determined for various intercalation protocols. The performance of this material was compared to that of several commercial graphites tested under the same conditions. The PILC carbon shows great promise as a Li-ion anode if the fade and first-cycle losses can be controlled.
Date: April 11, 2000
Creator: Guidotti, R. A.; Reinhardt, F. W. & Sandi, G.
Partner: UNT Libraries Government Documents Department

Recovery of Technetium and Iodine from Spent ATW TRISO Type Fuels.

Description: The Accelerator Transmutation of Waste (ATW) program is being developed to determine the feasibility of separating and transmutating the transactinides (Pu-Cm) and long-lived fission product (99Tc and 129I) from spent LWR fuel. Several types of ATW fuels have been suggested to transmutate the Pu-Cm fraction including TRISO type fuels. An ATW TRISO fuel would consist of a Pu-Cm oxide kernel surrounded by several layers of pyrolytic carbon, a layer of SiC, and an outer layer of pyrolytic carbon. Processing of the spent ATW fuel would involve the crush, burn, and leach approach used on normal TRISO fuels. This report describes experiments that determine the potential behavior of the two long-lived fission products, 99Tc and 129I, in this processing. Iodine can be removed and trapped during the burning of the carbon from the fuel. Some technetium may volatilize in the latter stages of the burn but the bulk of it will have to be recovered after dissolution of the oxide residue.
Date: January 1, 2001
Creator: Schroeder, N. C. (Norman C.) & Attrep, Moses
Partner: UNT Libraries Government Documents Department

TRISO-Fuel Element Performance Modeling for the Hybrid LIFE Engine with Pu Fuel Blanket

Description: A TRISO-coated fuel thermo-mechanical performance study is performed for the hybrid LIFE engine to test the viability of TRISO particles to achieve ultra-high burnup of a weapons-grade Pu blanket. Our methodology includes full elastic anisotropy, time and temperature varying material properties for all TRISO layers, and a procedure to remap the elastic solutions in order to achieve fast fluences up to 30 x 10{sup 25} n {center_dot} m{sup -2} (E > 0.18 MeV). In order to model fast fluences in the range of {approx} 7 {approx} 30 x 10{sup 25} n {center_dot} m{sup -2}, for which no data exist, careful scalings and extrapolations of the known TRISO material properties are carried out under a number of potential scenarios. A number of findings can be extracted from our study. First, failure of the internal pyrolytic carbon (PyC) layer occurs within the first two months of operation. Then, the particles behave as BISO-coated particles, with the internal pressure being withstood directly by the SiC layer. Later, after 1.6 years, the remaining PyC crumbles due to void swelling and the fuel particle becomes a single-SiC-layer particle. Unrestrained by the PyC layers, and at the temperatures and fluences in the LIFE engine, the SiC layer maintains reasonably-low tensile stresses until the end-of-life. Second, the PyC creep constant, K, has a striking influence on the fuel performance of TRISO-coated particles, whose stresses scale almost inversely proportional to K. Obtaining more reliable measurements, especially at higher fluences, is an imperative for the fidelity of our models. Finally, varying the geometry of the TRISO-coated fuel particles results in little differences in the scope of fuel performance. The mechanical integrity of 2-cm graphite pebbles that act as fuel matrix has also been studied and it is concluded that they can reliable serve the entire LIFE burnup cycle without ...
Date: February 18, 2010
Creator: DeMange, P; Marian, J; Caro, M & Caro, A
Partner: UNT Libraries Government Documents Department

Comparison of the electrochemical properties of several commercial graphites with a templated disordered carbon

Description: A templated carbon was prepared by the pyrolysis of pyrene impregnated into pillared clay (PILC). The electrochemical performance of this was evaluated with the goal of using this material as an anode in Li-ion cells. The reversible capacity was measured as a function of C rate and the cycling characteristics were determined for various intercalation protocols. The performance of this material was compared to that of several commercial graphites tested under the same conditions. The PILC carbon shows great promise as a Li-ion anode if the fade and first-cycle losses can be controlled.
Date: March 22, 2000
Creator: GUIDOTTI,RONALD A.; REINHARDT,FREDERICK W. & SANDI,GISELLE
Partner: UNT Libraries Government Documents Department

Multilayered nuclear fuel element

Description: A nuclear fuel element is described which is suitable for high temperature applications comprised of a kernel of fissile material overlaid with concentric layers of impervious graphite, vitreous carbon, pyrolytic carbon and metal carbide. The kernel of fissile material is surrounded by a layer of impervious graphite. The layer of impervious graphite is then surrounded by a layer of vitreous carbon. Finally, an outer shell which includes alternating layers of pyrolytic carbon and metal carbide surrounds the layer of vitreous carbon.
Date: December 1, 1996
Creator: Schweitzer, Donald G. & Sastre, Cesar
Partner: UNT Libraries Government Documents Department

Compatibility/Stability Issues in the Use of Nitride Kernels in LWR TRISO Fuel

Description: The stability of the SiC layer in the presence of free nitrogen will be dependent upon the operating temperatures and resulting nitrogen pressures whether it is at High Temperature Gas-Cooled Reactor (HTGR) temperatures of 1000-1400 C (coolant design dependent) or LWR temperatures that range from 500-700 C. Although nitrogen released in fissioning will form fission product nitrides, there will remain an overpressure of nitrogen of some magnitude. The nitrogen can be speculated to transport through the inner pyrolytic carbon layer and contact the SiC layer. The SiC layer may be envisioned to fail due to resulting nitridation at the elevated temperatures. However, it is believed that these issues are particularly avoided in the LWR application. Lower temperatures will result in significantly lower nitrogen pressures. Lower temperatures will also substantially reduce nitrogen diffusion rates through the layers and nitriding kinetics. Kinetics calculations were performed using an expression for nitriding silicon. In order to further address these concerns, experiments were run with surrogate fuel particles under simulated operating conditions to determine the resulting phase formation at 700 and 1400 C.
Date: February 1, 2012
Creator: Armstrong, Beth L & Besmann, Theodore M
Partner: UNT Libraries Government Documents Department

Data Compilation for AGR-3/4 Driver Particle Composite LEU03-09T

Description: This document is a compilation of characterization data for the AGR-3/4 driver fuel coated particle composite LEU03-09T, a composite of four batches of TRISO-coated, nominally 350 {micro}m diameter, 19.7% low enrichment uranium oxide/uranium carbide kernels (LEUCO). The AGR-3/4 driver fuel particles were fabricated using the AGR-1 baseline coating conditions and consist of a spherical kernel coated with an {approx}50% dense carbon buffer layer (100 {micro}m nominal thickness) followed by a dense inner pyrocarbon layer (40 {micro}m nominal thickness) followed by a SiC layer (35 {micro}m nominal thickness) followed by another dense outer pyrocarbon layer (40 {micro}m nominal thickness). the coated particles were produced by ORNL for the Advanced Gas Reactor Fuel Development and Qualification (AGR) program to be put into compacts, along with designed-to-fail particles, for insertion in the AGR-3 and AGR-4 irradiation test capsules. The kernels were obtained from BWXT and identified as composite G73V-20-69303. The BWXT kernel lot G73V-20-69303 was riffled into sublots for characterization and coating by ORNL and identified as LEU03-?? (where ?? is a series of integers beginning with 01).
Date: March 1, 2007
Creator: Hunn, John D & Lowden, Richard Andrew
Partner: UNT Libraries Government Documents Department

INERI-2006-003-F FY07 Annual Report

Description: Project Title: Comparison of Characterization Methods for Anisotropy and Microstructure of TRISO Particle Layers This INERI was created to support a comparative study between the newly developed two modulator generalized ellipsometry microscope (2-MGEM) at the Oak Ridge National Laboratory (ORNL) and the more traditional optical polarimeter (RAPAX) at the Commissariat l' nergie Atomique (CEA). These two systems are used to measure the anisotropy of the pyrocarbon layers in tri-isotropic (TRISO) coated particle fuel, which is an important parameter related to fuel performance. Although this project was only just started in June 2007, good progress has already been made. A kickoff meeting was held at ORNL on July 30-31, 2007 to present early progress and discuss details of the proposed work plan. This meeting was of great benefit to the participants, offering an opportunity to overcome the language barrier and more thoroughly communicate project relevant information. Each technical lead gave a presentation explaining the analysis techniques used in his task and presented data on early measurements of the German reference fuels. Plans were finalized regarding what work needed to be done and how to proceed with the comparative study. Possibilities for the inclusion of other coated particle samples, in addition to the two German reference fuels originally proposed, were also discussed. A list of these additional sample has now been generated and approved. Coating fragments from this series of different TRISO particle fuels have been sent from ORNL to the CEA and TEM analysis is in progress. Comparisons have already been made between the microstructure of the two German reference fuels which are the primary samples for this project. Specimens have also been prepared from the German reference fuels for comparative analysis between the 2-MGEM and RAPAX devices and initial measurements performed. Plans are to exchange specimens of the various fuel ...
Date: October 1, 2007
Creator: Hunn, John D
Partner: UNT Libraries Government Documents Department

Data Compilation for AGR-1 Variant 3 Coated Particle Composite LEU01-49T

Description: This document is a compilation of characterization data for the AGR-1 variant 3 coated particle composite LEU01-49T, a composite of three batches of TRISO-coated 350 {micro}m diameter 19.7% low enrichment uranium oxide/uranium carbide kernels (LEUCO). The AGR-1 TRISO-coated particles consist of a spherical kernel coated with a {approx} 50% dense carbon buffer layer (100 {micro}m nominal thickness) followed by a dense inner pyrocarbon layer (40 {micro}m nominal thickness) followed by a SiC layer (35 {micro}m nominal thickness) followed by another dense outer pyrcoarbon layer (40 {micro}m nominal thickness). The coated particles were produced by ORNL for the Advanced Gas Reactor Fuel Development and Qualification (AGR) program to be put into compacts for the fuel shakedown irradiation (AGR-1) experiment. The kernels were obtained from BWXT and identified as composite G73D-20-6302. The BWXT kernel lot G73D-20-69302 was riffled into sublots for characterization and coating by ORNL and identified as LEUO01-?? (where ?? is a series of integers beginning with 01).
Date: July 1, 2006
Creator: Hunn, John D & Lowden, Richard Andrew
Partner: UNT Libraries Government Documents Department

Data Compilation for AGR-1 Variant 3 Compact Lot LEU01-49T-Z

Description: This document is a compilation of characterization data for the AGR-1 vriant 3 fuel compact lot LEU01-49T-Z. The compacts were produced by ORNL for the Advanced Gas Reactor Fuel Development and Qualification (AGR) program for the first AGR irradiation test train (AGR-1). This compact lot was fabricated using particle composite LEU01-49T, which was a composite of three batches of TRISO-coated 350 {micro}m diameter 19.7% low enrichment uranium oxide/uranium carbide kernels (LEUCO). The AGR-1 TRISO-coated particles consist of a spherical kernel coated with an {approx} 50% dense carbon buffer layer (100 {micro}m nominal thickness), followed by a dense inner pyrocarbon layer (40 {micro}m nominal thickness), followed by a SiC layer (35 {micro}m nominal thickness), followed by another dense outer pyrocarbon layer (40 {micro}m nominal thickness). The kernels were obtained from BWXT and identified as composite G73D-20-69302. The BWXT kernel lot G73D-20-69302 was riffled into sublots for characterization and coating by ORNL and identified as LEU01-?? (where ?? is a series of integers beginning with 01). A data compilation for the AGR-1 variant 3 coated particle composite LEU01-49t CAN BE FOUND IN ornl/tm-2006/022.
Date: August 1, 2006
Creator: Hunn, John D; Montgomery, Fred C & Pappano, Peter J
Partner: UNT Libraries Government Documents Department

Results from ORNL Characterization of HRB-21 Reference Fuel

Description: This document is a compilation of the characterization data produced by ORNL for coated UCO fuel particles (350 {micro}m kernel diameter) fabricated by GA for the HRB-21 irradiation test capsule. The archived fuel particles form the batch used in HRB-21 were obtained by the Advanced Gas Reactor Fuel Development and Qualification (AGR) program for use as a reference material. The GA characterization data for this batch of fuel particles is presented in document GT-HTGR-88357, Rev. C, 'Capsule HRB-21 Preirradiation Report'. The archived fuel particles obtained by the AGR Program are from batch 8876-70, which was the parent batch for batch 8876-70-O, which was actually irradiated in HRB-21. The difference between batches 8876-70 and 8876-70-L is that the particles in batch 8876-70 do not have the seal coat and protective pyrocarbon coating (PPyC) that were deposited over the OPyC layer in batch 8876-70-O. The ORNL designation for the material characterized is AGR-10. This document summarizes characterization of the HRB-21 fuel for size, shape, coating thickness, and density. Fracture behavior and microstructural analysis of the layers and interfaces is compared to previous analyses of the German proof test particles (EU 2358-2365) published in ORNL/CF-04/06. Further detailed comparative study of the microstructure of these two reference materials would be valuable to continue to define the property differences between particles which exhibited good irradiation performance (the German particles) and poor irradiation performance (the HRB-21 particles).
Date: August 1, 2004
Creator: Hunn, John D
Partner: UNT Libraries Government Documents Department

Effects of deposition conditions on the properties of pyrolytic carbon deposited in a fluidized bed

Description: The high-density, isotropic pyrolytic carbon layer beneath the silicon carbide (IPyC) plays a key role in the irradiation performance of coated particle fuel. The IPyC layer protects the kernel from reactions with chlorine during deposition of the SiC layer, provides structural support for the SiC layer, and protects the SiC from fission products and carbon monoxide. The process conditions used by the Germans to deposit the IPyC coating produced a highly isotropic, but somewhat permeable IPyC coating. The permeability of the IPyC coating was acceptable for use with the dense German UO{sub 2} kernels, but may not be suitable when coating UCO kernels. The UCO kernels are typically more porous and thus have a larger surface area than UO{sub 2} kernels. The lower density and the higher surface area of UCO kernels could make them more susceptible to attack by HCl gas during the silicon carbide (SiC) coating process, which could result in heavy metal dispersion into the buffer and IPyC coatings and a higher level of as-manufactured SiC defects. The relationship between IPyC deposition conditions, permeability, and anisotropy must be understood and the appropriate combination of anisotropy and permeability for particle fuel containing UCO kernels selected. A reference set of processing conditions have been determined from review of historical information and results of earlier coating experiments employing 350 and 500 {micro}m UO{sub 2} kernels. It was decided that a limited study would be conducted, in which only coating gas fraction (CGF) and temperature would be varied. Coatings would be deposited at different rates and with a range of microstructures. Thickness, density, porosity and anisotropy would be measured and permeability evaluated using a chlorine leach test. The results would be used to select the best IPyC coating conditions for use with the available natural enrichment uranium carbide/uranium oxide (NUCO) kernels. ...
Date: September 1, 2005
Creator: Lowden, Richard Andrew; Hunn, John D; Nunn, Stephen D; Kercher, Andrew K; Price, Jeffery R & Jellison Jr, Gerald Earle
Partner: UNT Libraries Government Documents Department

Carbon based prosthetic devices

Description: This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project objective was to evaluate the use of carbon/carbon-fiber-reinforced composites for use in endoprosthetic devices. The application of these materials for the metacarpophalangeal (MP) joints of the hand was investigated. Issues concerning mechanical properties, bone fixation, biocompatibility, and wear are discussed. A system consisting of fiber reinforced materials with a pyrolytic carbon matrix and diamond-like, carbon-coated wear surfaces was developed. Processes were developed for the chemical vapor infiltration (CVI) of pyrolytic carbon into porous fiber preforms with the ability to tailor the outer porosity of the device to provide a surface for bone in-growth. A method for coating diamond-like carbon (DLC) on the articulating surface by plasma-assisted chemical vapor deposition (CVD) was developed. Preliminary results on mechanical properties of the composite system are discussed and initial biocompatibility studies were performed.
Date: December 31, 1998
Creator: Devlin, D.J.; Carroll, D.W.; Barbero, R.S.; Archuleta, T.; Klawitter, J.J.; Ogilvie, W. et al.
Partner: UNT Libraries Government Documents Department

Novel carbonaceous materials for lithium secondary batteries

Description: Carbonaceous materials have been synthesized using pillared clays (PILCs) as templates. The PILC was loaded with organic materials such as pyrene in the liquid and vapor phase, styrene in the vapor phase, trioxane, ethylene and propylene. The samples were then pyrolyzed at 700 C in an inert atmosphere, followed by dissolution of the inorganic template by conventional demineralization methods. X-ray powder diffraction of the carbons showed broad d{sub 002} peaks in the diffraction pattern, indicative of a disordered or turbostratic system. N{sub 2} BET surface areas of the carbonaceous materials range from 10 to 100 m{sup 2}/g. There is some microporosity (r < 1 nm) in the highest surface area carbons. Most of the surface area, however, comes from a mixture of micro and mesopores with radii of 2--5 nm. Electrochemical studies were performed on these carbons. Button cells were fabricated with capacity- limiting carbon pellets electrodes as the cathode a/nd metallic lithium foil as the anode. Large reversible capacities (up to 850 mAh/g) were achieved for most of the samples. The irreversible capacity loss was less than 180 mAh/g after the first cycle, suggesting that these types of carbon materials are very stable to lithium insertion and de-insertion reactions.
Date: July 1, 1997
Creator: Sandi, G.; Winans, R.E.; Carrado, K.A. & Johnson, C.S.
Partner: UNT Libraries Government Documents Department

Sound velocity of carbon at high pressures

Description: We have measured the sound velocity in shock compressed graphite. The data are consistent with a model of solid diamond from 0.8 to 1.4 Mbar. 18 references.
Date: September 11, 1984
Creator: Shaner, J.W.; Brown, J.M.; Swenson, C.A. & McQueen, R.G.
Partner: UNT Libraries Government Documents Department

Pore structure and growth kinetics in carbon materials

Description: Pore structure of glassy carbon (GC) and pyrolytic graphite (PG) have been investigated. GC is one of the most impervious of solids finding applications in prosthetic devices and fuel cells while PG is used extensively in the aerospace industry. One third of the microstructure of GC consists of closed pores inaccessible to fluids. The microstructure of this material has been characterized using x-ray diffraction (XRD) and high resolution electron microscopy. Small angle x-ray scattering (SAXS) has been used to measure the angstrom sized pores and to follow the evolution of pore surface area as a function of heat treatment temperature (HTT) and heat treatment time (HTt) at constant temperature. From these measurements an analysis of the surface area kinetics was made to find out if rate processes are involved and to locate graphitization occurring at pore surfaces. PG on the other hand has been found to have larger sized pores that comprise five percent of its volume. In addition to being closed these pores are oriented. Some pore models are proposed for PG and the existing scattering theory from oriented ellipsoids is modified to include the proposed shapes.
Date: April 1, 1978
Creator: Bose, S.
Partner: UNT Libraries Government Documents Department

Ceramographic Examinations of Irradiated AGR-1 Fuel Compacts

Description: The AGR 1 experiment involved irradiating 72 cylindrical fuel compacts containing tri-structural isotropic (TRISO)-coated particles to a peak burnup of 19.5% fissions per initial metal atom with no in-pile failures observed out of almost 300,000 particles. Five irradiated AGR 1 fuel compacts were selected for microscopy that span a range of irradiation conditions (temperature, burnup, and fast fluence). These five compacts also included all four TRISO coating variations irradiated in the AGR experiment. The five compacts were cross-sectioned both transversely and longitudinally, mounted, ground, and polished after development of careful techniques for preserving particle structures against preparation damage. Approximately 40 to 80 particles within each cross section were exposed near enough to mid-plane for optical microscopy of kernel, buffer, and coating behavior. The microstructural analysis focused on kernel swelling and porosity, buffer densification and fracture, debonding between the buffer and inner pyrolytic carbon (IPyC) layers, and fractures in the IPyC and SiC layers. Three basic particle morphologies were established according to the extent of bonding between the buffer and IPyC layers: complete debonding along the interface (Type A), no debonding along the interface (Type B), and partial debonding (Type AB). These basic morphologies were subdivided according to whether the buffer stayed intact or fractured. The resulting six characteristic morphologies were used to classify particles within each cross section, but no spatial patterns were clearly observed in any of the cross-sectional morphology maps. Although positions of particle types appeared random within compacts, examining a total of 830 classified particles allowed other relationships among morphological types to be established.
Date: May 1, 2012
Creator: Demkowicz, Paul; Ploger, Scott & Hunn, John
Partner: UNT Libraries Government Documents Department

Detailed Reaction Kinetics for CFD Modeling of Nuclear Fuel Pellet Coating for High Temperature Gas-Cooled Reactors

Description: The research project was related to the Advanced Fuel Cycle Initiative and was in direct alignment with advancing knowledge in the area of Nuclear Fuel Development related to the use of TRISO fuels for high-temperature reactors. The importance of properly coating nuclear fuel pellets received a renewed interest for the safe production of nuclear power to help meet the energy requirements of the United States. High-temperature gas-cooled nuclear reactors use fuel in the form of coated uranium particles, and it is the coating process that was of importance to this project. The coating process requires four coating layers to retain radioactive fission products from escaping into the environment. The first layer consists of porous carbon and serves as a buffer layer to attenuate the fission and accommodate the fuel kernel swelling. The second (inner) layer is of pyrocarbon and provides protection from fission products and supports the third layer, which is silicon carbide. The final (outer) layer is also pyrocarbon and provides a bonding surface and protective barrier for the entire pellet. The coating procedures for the silicon carbide and the outer pyrocarbon layers require knowledge of the detailed kinetics of the reaction processes in the gas phase and at the surfaces where the particles interact with the reactor walls. The intent of this project was to acquire detailed information on the reaction kinetics for the chemical vapor deposition (CVD) of carbon and silicon carbine on uranium fuel pellets, including the location of transition state structures, evaluation of the associated activation energies, and the use of these activation energies in the prediction of reaction rate constants. After the detailed reaction kinetics were determined, the reactions were implemented and tested in a computational fluid dynamics model, MFIX. The intention was to find a reduced mechanism set to reduce the computational time ...
Date: November 29, 2008
Creator: Battaglia, Francine
Partner: UNT Libraries Government Documents Department

Nuclear Safeguards Considerations For The Pebble Bed Modular Reactor (PBMR)

Description: High temperature reactors (HTRs) have been considered since the 1940s, and have been constructed and demonstrated in the United Kingdom (Dragon), United States (Peach Bottom and Fort Saint Vrain), Japan (HTTR), Germany (AVR and THTR-300), and have been the subject of conceptual studies in Russia (VGM). The attraction to these reactors is that they can use a variety of reactor fuels, including abundant thorium, which upon reprocessing of the spent fuel can produce fissile U-233. Hence, they could extend the stocks of available uranium, provided the fuel is reprocessed. Another attractive attribute is that HTRs typically operate at a much higher temperature than conventional light water reactors (LWRs), because of the use of pyrolytic carbon and silicon carbide coated (TRISO) fuel particles embedded in ceramic graphite. Rather than simply discharge most of the unused heat from the working fluid in the power plant to the environment, engineers have been designing reactors for 40 years to recover this heat and make it available for district heating or chemical conversion plants. Demonstrating high-temperature nuclear energy conversion was the purpose behind Fort Saint Vrain in the United States, THTR-300 in Germany, HTTR in Japan, and HTR-10 and HTR-PM, being built in China. This resulted in nuclear reactors at least 30% or more thermodynamically efficient than conventional LWRs, especially if the waste heat can be effectively utilized in chemical processing plants. A modern variant of high temperature reactors is the Pebble Bed Modular Reactor (PBMR). Originally developed in the United States and Germany, it is now being redesigned and marketed by the Republic of South Africa and China. The team examined historical high temperature and high temperature gas reactors (HTR and HTGR) and reviewed safeguards considerations for this reactor. The following is a preliminary report on this topic prepared under the ASA-100 Advanced Safeguards ...
Date: October 1, 2009
Creator: Durst, Phillip Casey; Beddingfield, David; Boyer, Brian; Bean, Robert; Collins, Michael; Ehinger, Michael et al.
Partner: UNT Libraries Government Documents Department

Physical Characterization and Steam Chemical Reactivity of Carbon Fiber Composites

Description: This report documents experiments and analyses that have been done at the Idaho National Engineering and Environmental Laboratory (INEEL) to measure the steam chemical reactivity of two types of carbon fiber composites, NS31 and NB31, proposed for use at the divertor strike points in an ITER-like tokamak. These materials are 3D CFCs constituted by a NOVOLTEX preform and densified by pyrocarbon infiltration and heat treatment. NS31 differs from NB31 in that the final infiltration was done with liquid silicon to reduce the porosity and enhance the thermal conductivity of the CFC. Our approach in this work was twofold: (1) physical characterization measurements of the specimens and (2) measurements of the chemical reactivity of specimens exposed to steam.
Date: May 1, 2001
Creator: Anderl, Robert Andrew; Pawelko, Robert James & Smolik, Galen Richard
Partner: UNT Libraries Government Documents Department

PARFUME Theory and Model basis Report

Description: The success of gas reactors depends upon the safety and quality of the coated particle fuel. The fuel performance modeling code PARFUME simulates the mechanical, thermal and physico-chemical behavior of fuel particles during irradiation. This report documents the theory and material properties behind vari┬Čous capabilities of the code, which include: 1) various options for calculating CO production and fission product gas release, 2) an analytical solution for stresses in the coating layers that accounts for irradiation-induced creep and swelling of the pyrocarbon layers, 3) a thermal model that calculates a time-dependent temperature profile through a pebble bed sphere or a prismatic block core, as well as through the layers of each analyzed particle, 4) simulation of multi-dimensional particle behavior associated with cracking in the IPyC layer, partial debonding of the IPyC from the SiC, particle asphericity, and kernel migration (or amoeba effect), 5) two independent methods for determining particle failure probabilities, 6) a model for calculating release-to-birth (R/B) ratios of gaseous fission products that accounts for particle failures and uranium contamination in the fuel matrix, and 7) the evaluation of an accident condition, where a particle experiences a sudden change in temperature following a period of normal irradiation. The accident condi┬Čtion entails diffusion of fission products through the particle coating layers and through the fuel matrix to the coolant boundary. This document represents the initial version of the PARFUME Theory and Model Basis Report. More detailed descriptions will be provided in future revisions.
Date: September 1, 2009
Creator: Knudson, Darrell L.; Miller, Gregory K; Miller, G.K.; Petti, D.A.; Maki, J.T. & Knudson, D.L.
Partner: UNT Libraries Government Documents Department