Dissertationen zum Thema „Reactor performance“
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1
Ogata, Takanari. „Performance of Metallic Fast Reactor Fuel“. Kyoto University, 2000. http://hdl.handle.net/2433/157094.
Annotation:
本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものであるKyoto University (京都大学)
0048
新制・論文博士
博士(工学)
乙第10401号
論工博第3515号
新制||工||1183(附属図書館)
UT51-2000-F467
(主査)教授 芹澤 昭示, 教授 東 邦夫, 教授 小岩 昌宏
学位規則第4条第2項該当
2
ANDRZEJEWSKI, CLAUDIO S. „Avaliação de alternativas de combustível tipo placa para reatores de pequeno porte“. reponame:Repositório Institucional do IPEN, 2005. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11364.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
3
Nachaiyasit, Suyanee. „The effect of process parameters on reactor performance in an anaerobic baffled reactor“. Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481427.
4
Chugunov, Svyatoslav. „High-Performance Simulations for Atmospheric Pressure Plasma Reactor“. Diss., North Dakota State University, 2012. https://hdl.handle.net/10365/26626.
Annotation:
Plasma-assisted processing and deposition of materials is an important component of modern industrial applications, with plasma reactors sharing 30% to 40% of manufacturing steps in microelectronics production [1]. Development of new flexible electronics increases demands for efficient high-throughput deposition methods and roll-to-roll processing of materials. The current work represents an attempt of practical design and numerical modeling of a plasma enhanced chemical vapor deposition system. The system utilizes plasma at standard pressure and temperature to activate a chemical precursor for protective coatings. A specially designed linear plasma head, that consists of two parallel plates with electrodes placed in the parallel arrangement, is used to resolve clogging issues of currently available commercial plasma heads, as well as to increase the flow-rate of the processed chemicals and to enhance the uniformity of the deposition. A test system is build and discussed in this work. In order to improve operating conditions of the setup and quality of the deposited material, we perform numerical modeling of the plasma system. The theoretical and numerical models presented in this work comprehensively describe plasma generation, recombination, and advection in a channel of arbitrary geometry. Number density of plasma species, their energy content, electric field, and rate parameters are accurately calculated and analyzed in this work. Some interesting engineering outcomes are discussed with a connection to the proposed setup. The numerical model is implemented with the help of high-performance parallel technique and evaluated at a cluster for parallel calculations. A typical performance increase, calculation speed-up, parallel fraction of the code and overall efficiency of the parallel implementation are discussed in details.
5
Johnson, Kyle D. „High Performance Fuels for Water-Cooled Reactor Systems“. Doctoral thesis, KTH, Reaktorfysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-201604.
Annotation:
Investigation of nitride fuels and their properties has, for decades, been propelled on the basis of their desirable high metal densities and high thermal conductivities, both of which oer intrinsic advantages to performance, economy, and safety in fast and light water reactor systems. In this time several key obstacles have been identied as impeding the implementation of these fuels for commercial applications; namely chemical interactions with air and steam, the noted diculty in sintering of the material, and the high costs associated with the enrichment of 15N. The combination of these limitations, historically, led to the well founded conclusion that the most appropriate use of nitride fuels was in the fast reactor fuel cycle, where the cost burdens associated with them is substantially less. Indeed, it is within this context that the vast majority of work on nitrides has been and continues to be done. Nevertheless, following the 2011 Fukushima-Daiichi nuclear accident, a concerted governmental-industrial eort was embarked upon to explore the alternatives of so-called \accident tolerant" and \high performance" fuels. These fuels would, at the same time, improve the response of the fuel-clad system to severe accidents and improve the economy of operation for light water reactor systems. Among the various candidates proposed are uranium nitride, uranium silicide, and a third \uranium nitride-silicide" composite featuring a mixture of the former. In this thesis a method has been established for the synthesis, fabrication, and characterization of high purity uranium nitride, and uranium nitride-silicide composites, prepared by the spark plasma sintering (SPS) technique. A specic result has been to isolate the impact of the processing parameters on the microstructure of representative fuel pellets, essentially permitting any conceivable microstructure of interest to be fabricated. This has enabled the development of a highly reproducible technique for the production of pellets with microstructures tailored towards any desired porosity between 88-99.9%TD, any grain size between 6-24 μm, and, in the case of the uranium nitride-silicide composite, a silicide-coated UN matrix. This has permitted the evaluation of these microstructural characteristics on the performance of these materials, specically with respect to their role as accident tolerant fuels. This has generated results which have tightly coupled nitride performance with pellet microstructure, with important implications for the use of nitrides in water-cooled reactors.Under artionden har forskning om nitridbranseln och dess egenskaper bedrivits pa grundval av nitridbransletsatravarda egenskaper avseende dess hoga metall tathet och hog varmeledningsformaga. Dessa egenskaper besitter vasentliga fordelar avseende prestanda, ekonomi och sakerhet for metallkylda som lattvatten reaktorer. Genom forskning har aven centrala begr ansningar identierats for implementering av nitridbranslen for kommersiellt bruk. Begransningar avser den kemiska interaktionen med luft och vattenanga, en uppmarksammad svarighet att sintring av materialet samt hoga kostnader forknippade med den nodvandiga anrikningen av 15-N. Kombinationen av dessa begransningar resulterade, tidigare, i en valgrundad slutsats att nitridbranslet mest andamalsenliga anvandningsomrade var i karnbranslecykeln for snabba reaktorer. Detta da kostnaderna forenade med implementeringen av branslet ar avsevart lagre. Inom detta sammanhang har majoriteten av forskning avseende nitrider bedrivits och fortskrider an idag. Dock, efter karnkraftsolyckan i Fukushima-Daiichi 2011, inleddes en samlad industriell och statlig anstrangning for att undersoka alternativ till sa kallade \olyckstoleranta" och \hogpresterande" branslen. Dessa branslen skulle samtidigt forbattra reaktionstiden for bransleinkapsling systemet mot allvarliga olyckor samt forbattra driftsekonomin av lattvattenreaktorer. Foreslagna kandidater ar urannitrid, uransilicid och en tredje \uran nitrid-silicid", komposit bestaende av en blandning av de foregaende. Genom denna avhandling har en metod faststallts for syntes, tillverkning och karaktarisering av uran nitrid av hog renhet samt uran nitrid-silicid kompositer, forberedda med tekniken SPS (Spark Plasma Sintering). Ett specikt resultat har varit att isolera eekten av processparametrar pa mikrostrukturen pa representativa branslekutsar. Detta mojliggor, i princip, framstallningen av alla tankbara mikrostrukturer utav intresse for tillverkning. Vidare har detta mojliggjort utvecklingen av en hogeligen reproducerbar teknik for framstallningen av branslekutsar med mikrostrukturer skraddarsydda for onskad porositet mellan 88 och 99.9 % TD, och kornstorlek mellan 6 och 24 μm. Dartill har en metod for att belagga en matris av uran nitrid-silicid framarbetats. Detta har mojliggjort utvarderingen av dessa mikrostrukturella parametrars paverkan pa materialens prestanda, sarskilt avseende dess roll som olyckstoleranta branslen. Detta har genererat resultat som ar tatt sammanlankat nitridbranslets prestanda till kutsens mikrostruktur, med viktiga konsekvenser for den potentiella anvandningen av nitrider i lattvatten reaktorer.
QC 20170210
6
Ortega, Gómez Tino. „Stability analysis of the high performance light water reactor“. Karlsruhe Forschungszentrum Karlsruhe, 2009. http://d-nb.info/994365624/34.
7
Grobicki, Ania Maria Wanda. „Hydrodynamic characteristics and performance of the anaerobic baffled reactor“. Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/7406.
8
Simmons, Josh C. „Fukushima Meltdown Reactor: Burn Everything“. Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1428239598.
9
Peluso, Enzo. „Eggshell catalyst for hydrocarbon synthesis, kinetic modeling and reactor performance“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0033/MQ30754.pdf.
10
Liu, Lingling. „Ammonia removal from industrial wastewater, analysis of photochemical reactor performance“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/MQ57718.pdf.
11
Liu, Lingling Carleton University Dissertation Engineering Civil and Environmental. „Ammonia removal from industrial wastewater-analysis of photochemical reactor performance“. Ottawa, 1999.
12
Van, Zyl Pierrie Jakobus. „Anaerobic digestion of Fischer-Tropsch reaction water : submerged membrane anaerobic reactor design, performance evaluation & modeling“. Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/4994.
13
Njoya, Mahomet. „Reactor reconfiguration for enhanced performance of a down-flow expanded granular bed reactor (Degbr) for poultry slaughterhouse treatment“. Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2599.
Annotation:
Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017.The poultry industry is one of the largest industries in the South African agricultural sector. To sustain their various operations, this industry utilises a large quantity of potable water to process slaughtered birds in order to satisfy hygiene and sanitation requirements in processing facilities. Thus, the consumption of potable water during poultry slaughterhouse operations results in the production of high-strength poultry slaughterhouse wastewater (PSW), which is laden with a variety of pollutants, including fats, oil and grease (FOG), carcass debris, feathers and organic matter, including proteins, that should be removed from the wastewater, or at least reduced in concentration, prior to the PSW being discharged into the environment. This is to avoid and/or minimise levies and non-compliance penalties from monitoring institutions in charge of controlling the quality of effluents in the area from which the PSW was collected for this study. Furthermore, the option of treating and recycling the PSW to address the current issue of water scarcity in the Western Cape (South Africa), and to minimise possible harmful effects on the environment, will reduce the overreliance on slaughterhouses in the region on potable/drinking water, thus also lessening running costs associated with water procurement for operations. Various technologies, involving physical, chemical or biological processes, have been evaluated for the treatment of PSW, with this study focusing on anaerobic treatment (part of the biological treatment) of PSW, using a high-rate anaerobic bioreactor system (HRABs), which provides for low production of sludge, the production of biogas as a source of energy and the provision of high performance in terms of organic matter removal. Moreover, HRABs are cheaper, when compared to other aerobic treatment technologies. However, numerous potential challenges were encountered when using HRABs, such as low production of biogas due to gas entrapment, head losses across the granular bed, sludge washout in upflow HRABs, uneven wastewater distribution, and thus poor dispersion of the organic matter, which impacts on the adequacy of treatment, poor release of toxic substances contained in the entrapped biogas (NH3 or H2S), clogging of the underdrain system for down-flow HRABs, or the formation of dead zones within the granular bed, resulting in short-circuiting.
14
Saayman, Jean. „Combined hydrodynamic and reaction analysis of a bubbling to turbulent Fluidized Bed Reactor“. Thesis, University of Pretoria, 2013. http://hdl.handle.net/2263/40221.
Annotation:
There are many large-scale contacting methods for gas reactions requiring a solid catalyst. The catalytic gas-solid Fluidized Bed Reactor (FBR) is one of the popular methods in industry. In FBRs the bulk of the gas throughput is present as lean bubbles, mostly deprived of solids, bubbling through a solids-rich emulsion phase. The movement of gas into and out of the emulsion often dictates the performance of an FBR. During the past five decades major contributions have been made towards the understanding of FBRs, although numerous gaps still exist, especially at higher bubbling regime velocities.
This work follows an integrated approach for the simultaneous measurement of hydrodynamics and reactor performance. Hydrodynamics are measured using fast X-Ray Tomography (XRT), pressure analysis techniques and an optical fibre probe. Reactor performance is measured by utilizing the ozone decomposition reaction. Performance is quantified using a basic two-phase reactor model with an apparent overall interphase mass transfer (K0) parameter. Two 14 cm (ID) fluidized bed columns are used, one setup supporting the ozone decomposition reaction and the other installed within a fast XRT facility. Special emphasis is placed on superficial velocities (U0) spanning the entire bubbling regime up to the onset of the turbulent regime (Uc). The particle types employed are Geldart B sand particles and highly dense ferro-silicon (FeSi) particles. Fines are added to both particle types, resulting in a total of four particle systems (sand baseline; sand with fines; FeSi baseline; FeSi with fines). Time constraints on the XRT equipment limited the tomography measurements to the sand baseline particle system. The hydrodynamics of the
other particle systems were limited to the pressure signal and optical probe measurements of the ozone decomposition setup.
The results of the sand baseline system suggest that a distinction should be made between the low-interaction bubbling regime and the high-interaction bubbling regime. A change in mass transfer behaviour occurs around a U0/Uc value of 0.25. Reactor performance increases up to U0/Uc = 0.7, after which a decreasing trend is observed. An empirical correlation is proposed for the specific interphase mass transfer (kbe) of the higher velocity bubbling regime. This correlation is based on the integration of the hydrodynamics determined by means of XRT and reactor performance:
4-12
The hydrodynamic parameter β gives the best fit for the entire velocity range with an average error of 8%, although it is not recommended for U0/Uc<0.17. It is observed that the classical approach of penetration theory for interphase mass transfer, performs exceptionally well at low velocities (U0/Uc<0.34).
The addition of fines to the FeSi particle type decreases the overall reactor performance, despite decreased bubble sizes. The solids fraction, however, unexpectedly increases with the addition of fines and a collapse of the emulsion phase is measured. It is therefore postulated that though flow in the emulsion phase is much higher for the FeSi baseline system and decreases with the addition of fines. For the sand particle type, the behaviour expected from literature is observed: reactor performance increases, bubble sizes decrease and the solids fraction decreases.
Very distinct hydrodynamic behaviour is observed for all the fluidization regimes with XRT. Probability density distributions show there are still two phases present in the turbulent regime and that the emulsion-phase solids fraction remains independent of velocity until fast fluidization sets in. The turbulent regime has unique hydrodynamic behaviour, although voids appear to be a transient structure between the structures of the bubbling and fast fluidization regimes.Thesis (PhD)--University of Pretoria, 2013.
gm2014
Chemical Engineering
unrestricted
15
何沛德 und Pui-tak Ho. „Control and operation of high-performance thyristor-controlled-reactor(TCR) compensators“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1988. http://hub.hku.hk/bib/B31231160.
16
Brink, Hendrik Gideon. „Multi-Vortex distributor : effect on 2-D fluidized bed reactor performance“. Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/25719.
Annotation:
The influence of the distributor configuration on the mass transfer and bubble sizes in a 2-D FBR was studied for two types of distributor configurations: - A novel multi-vortex (MV) distributor with tuyéres directed vertically and horizontally at different heights.
- A standard perforated plate distributor (baseline).
- Uc Baceline = 0.30 m/s.
- Uc MV distributor = 0.25 m/s.
Dissertation (MEng)--University of Pretoria, 2011.
Chemical Engineering
unrestricted
17
Giudici, Ben Charles. „Aspects of circuit breaker performance during high voltage shunt reactor switching“. Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27881.
Annotation:
High voltage shunt reactor switching is a difficult circuit breaker duty. Severe reactor network insulation stresses can occur on breaker current chopping and even more so on breaker reignition. Predicting reactor switching transients is fundamental to assessing insulation concerns, and evaluating circuit breaker performance.
This work demonstrates measurement of circuit breaker interruption characteristics relevant to reactor switching, and their use in computer simulation of reactor switching transients. A technique for predicting circuit breaker reactor switching performance through simulation is also introduced and tested.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
18
NASCIMENTO, CLAUDIO S. do. „Aplicacao da metodologia fuzzy na quantificacao da probabilidade de erro humano em instalacoes nucleares“. reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9496.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
19
Ortega, Gómez Tino [Verfasser]. „Stability analysis of the high performance light water reactor / Tino Ortega Gómez“. Karlsruhe : Forschungszentrum Karlsruhe, 2009. http://d-nb.info/994365624/34.
20
Blair, Stuart R. „Thermal hydraulic performance analysis of a small integral pressurized water reactor core“. Thesis, Springfield, Va. : Available from National Technical Information Service, 2003. http://handle.dtic.mil/100.2/ADA417648.
Annotation:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003.Thesis supervisor: Neil E. Todreas. Includes bibliographical references (p. 117-121). Also available online.
21
Blair, Stuart R. (Stuart Ryan) 1972. „Thermal hydraulic performance analysis of a small integral pressurized water reactor core“. Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17029.
Annotation:
Thesis (Nucl. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003.Includes bibliographical references (p. 117-121).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
A thermal hydraulic analysis of the International Reactor Innovative and Secure (IRIS) core has been performed. Thermal margins for steady state and a selection of Loss Of Flow Accidents have been assessed using three methodologies to account for uncertainty. The thermal hydraulic analysis has shown that the IRIS is designed with adequate thermal margin for steady state operation, the locked rotor/shaft shear accident (LR/SS) and for variants of the partial loss of flow accident. To treat uncertainties, three methods were used, ranging from conservative, deterministic methods, to more realistic and computationally demanding Monte Carlo-based methods. To facilitate the computational requirements of the thermal hydraulic analysis, a script-based interface was created for VIPRE. This scripted interface (written in Matlab) supplants the existing file-based interface. This interface allows for repeated, automatic execution of the VIPRE code on a script-modifiable input data, and parses and stores output data to disk. This endows the analyst with much greater power to use VIPRE in parametric studies, or using the Monte Carlo-based uncertainty analysis methodology. The Matlab environment also provides powerful visualization capability that greatly eases the task of data analysis.
by Stuart R. Blair.
Nucl.E.and S.M.
22
Fu, Kang. „Experimental and analytic evaluation of gas-cooled reactor cavity cooling system performance“. Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13290.
23
Cubas, Suazo Francisco Jose. „Effect of Reactor Feeding Pattern on Performance of an Activated Sludge SBR“. Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/35311.
Annotation:
The possible effects of changes in the feeding pattern on activated sludge properties related to bioflocculation have been analyzed in lab scale sequencing batch reactors (SBR) in order to determine if these changes in effluent water quality and settling and dewatering properties are significant, so they can be considered in future studies or if they can be recommended as crucial when operating and designing wastewater treatment plants. The activated sludge process is widely used to treat wastewater from both industrial and municipal sources. Biomass from industrial facilities containing high monovalent to divalent ion content usually settles poorly, which leads to low quality effluents that fail to meet environmental requirements. Therefore, the combined effect of feeding pattern plus the addition of sodium to activated sludge reactors was studied in this experiment.
A series of SBRs were operated at different sodium concentrations that ranged from 1.5 - 15 meq/L and different feeding times that ranged from 1 minute to 4 hours. Biomass samples were taken from each reactor to study the settling and dewatering properties and effluent samples were used to analyze the amount of organic matter and exocellular polymeric substances present due to deflocculation. As expected, the changes in feeding strategies affected all of the properties measured. When the feeding time was maintained low (pulse feed) the effluent quality and settling properties were the best. As the feeding time was increased the effluent quality, settling, and dewatering properties increased suggesting that the way in which the reactors were fed affected the overall bioflocculation process. The causes of the high deflocculation observed are not well understood, but data suggest that a microbial community change could have affected exocellular biopolymers which are believed to play an important role on bioflocculation.
This research demonstrates the importance of the interaction between cation content and feeding pattern when operating a wastewater treatment plants and when reporting lab-scaled results related to settling and bioflocculation.
Master of Science
24
James, Kris. „The design and performance of a civil marine reactor with regard to the thermal performance of the fuel“. Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18067/.
Annotation:
There is a concerted world wide effort to limit greenhouse gases into the atmosphere. Civil shipping accounts for a 3 % proportion of greenhouse gas emissions and to combat this problem, nuclear power is proposed as an alternative energy source. This thesis set out to evaluate the use of a civil marine nuclear reactor for commercial shipping purposes. A review was carried out to determine past uses of civil marine nuclear reactors to assist specification of the criteria for a civil ship reactor e.g. reactor type, operating conditions. The refuelling period of such ships was understood as an issue for commercial success and so having fuel in the reactor for periods of 15 years was determined to be a key goal, as well as keeping the fissile enrichment of the fuel low. Computational simulation of the thermo-mechanical performance on fuel rods under expected operating conditions for a civil marine reactor were conducted. Higher thermal efficiency in the fuel rods was determined to be key in achieving long refuelling periods. Fabrication of simulant fuel cermets was undertaken with spark plasma sintering to produce simulant cermet fuel pellets with improved thermal conductivity and was evaluated to be an efficient cermet production route. This was achieved with YSZ as a simulant for UO2 fuel, with metallic Mo and W to produce stable cermets at varying metallic loading. The thermal conductivity values were found to increase by a factor of 2-3 with up to 30 % metallic loading. The final aspect of this thesis focused on finite element simulation, studying the shape of metallic loading inside a cermet to determine a suitable layout to provide the greatest thermal transfer with several candidate geometries determined to be appropriately suitable.
25
Ibrahim, Hadeel. „Novel photocatalytic reactor for the destruction of airborne pollutants, design and performance testing“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0003/MQ30696.pdf.
26
Barber, William Pablo. „Effect of nitrate and sulphate on the performance of an anaerobic baffled reactor“. Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311601.
27
Zhao, Xiao [Verfasser], Wolfgang [Akademischer Betreuer] Marquardt und Martin [Akademischer Betreuer] Mönnigmann. „Reactor network synthesis with guaranteed robust performance / Xiao Zhao ; Wolfgang Marquardt, Martin Mönnigmann“. Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1162450789/34.
28
STAMPA, CLEYTON SENIOR. „EXPERIMENTAL PRELIMINARY STUDY OF THE THERMAL PERFORMANCE OF A AP-600 TYPE REACTOR“. PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1994. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=19305@1.
Annotation:
No presente trabalho realizou-se um estudo experimental preliminar sobre o desempenho térmico do sistema de resfriamento da contenção de um reator LWR do tipo AP-600.
Foi projetado, construído e testado um aparato experimental similar ao vaso de contenção dotado de uma piscina com fonte quente e resfriado externamente por circulação forçada de ar. Neste arranjo, foram testados os efeitos do volume de água, potencia dissipada e da vazão externa do ar.
Nos ensaios, foram observadas três regiões típicas nos perfis de temperatura, regime de pré-saturação da água da piscina, regime transitório com ebulição interna e finalmente, equilíbrio térmico global, onde todo o calor fornecido pela fonte quente era removido pelo ar externo.In the present work, na experimental primliminary study of the thermal perfomance of a AP-600 type reactor containment cooling system was performed. It was designed, constructed and tested an experimental apparatus similar to the containment vessel equipped with a hot source inside a water pool and cooled externally by means of forced air circulation. Several tests were performed to observe the effects of the water volume, the dissipated power and external air flow rate. During the tests, threee typical regions were observed, pre-saturation water regime, transitory regime with internal boilling and, eventually, steady state regime where all the heat generated by the heat source was removed by the external air.
29
Mattingly, Brett T. (Brett Thomas). „Performance analysis of matrix fuel for a passive pressure tube light water reactor“. Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/38099.
30
Wang, Jing 1976. „An integrated performance model for high temperature gas cooled reactor coated particle fuel“. Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28368.
Annotation:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2004.Includes bibliographical references (p. 290-300).
The performance of coated fuel particles is essential for the development and deployment of High Temperature Gas Reactor (HTGR) systems for future power generation. Fuel performance modeling is indispensable for understanding the physical behavior of fuel particles and achieving their high reliability during operations and accidents through a guided design process. This thesis develops an integrated fuel performance model of coated particle fuel to comprehensively study its mechanical behavior and define an optimum fuel design strategy with the aid of the model. Key contributions of the thesis include a pyrocarbon layer crack induced particle failure model with a fracture mechanics approach, mechanical analysis of particles with better representation of irradiation induced creep, a proposed fuel optimization procedure, the capability to simulate arbitrary irradiation histories, and the incorporation of Monte Carlo sampling to account for the statistical variation of particle properties.
(cont.) Stress calculations in this model were benchmarked with the FUEL code and finite element calculations of Idaho National Engineering and Environmental Laboratory (INEEL) and with model predictions for High Temperature Test Reactor (HTTR) first- loading fuel. Fuel failure predictions were made for New Production-Modular HTGR irradiated fuel capsules, which show good agreements with experiments. Based on the simulations, it is suggested that in most cases the pyrocarbon crack induced fuel failure mechanism plays a much more important role in fuel performance than the more widely accepted pressure vessel fuel failure mechanism. After the establishment of the model, parametric study was conducted to find out the effects of various input variables on fuel performance, and fuel design and optimization procedure was proposed accordingly. Simulations with optimized fuel configurations demonstrate that superior fuel performance can be achieved with model analysis. The model also prepares interfaces for further improvements on various modules upon arrival of new information.
by Jin Wang.
Ph.D.
31
Buckley, James. „The manufacture and characterisation of composite nuclear fuel for improved in-reactor performance“. Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/the-manufacture-and-characterisation-of-composite-nuclear-fuel-for-improved-inreactor-performance(b5ea0339-7c5b-46d2-a696-743007b9e94b).html.
Annotation:
Fuel for nuclear reactors with an increased thermal conductivity offers the potential for lower fuel operating temperatures and reduced fission gas release rates. Uranium dioxide (UO2) based composites offer a method of achieving a higher thermal conductivity. Silicon carbide (SiC) and molybdenum (Mo) have been identified as potential candidates for use in a composite fuel material. Uranium dioxide composites were manufactured with the inclusion of whiskers and granules of SiC up to a 30 vol% loading. The manufacturing route used was based on the current process employed to commercially manufacture UO2 fuel, by reductive sintering. Composites containing Mo were manufactured via spark plasma sintering and included loadings of up to 10 vol% Mo. The composites were characterised on their microstructural properties and where appropriate the thermal conductivity was determined by laser flash analysis. The composites containing SiC achieved low densities, 95%TD. The microstructure contained channel like structures of Mo, due to the use of an agglomerated UO2 precursor powder. An increased thermal conductivity was determined for the molybdenum composites. At the maximum measurement temperature of 800°C the increase was found to be 68% in the 10 vol% composites compared to UO2.
32
Kane, Jason Patrick. „Water quality performance of a reciprocating biofilm reactor for treatment of dairy wastewater“. DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/439.
Annotation:
Removal of organic matter and nitrogen from concentrated wastewaters is often a complex and costly process that is rarely implemented in animal agriculture, such as the dairy industry, despite regulatory pressures and the high cost of land for manure application in some regions. This paper describes results from the first implementation for treatment of dairy farm wastewater of the relatively simple ReCip® technology. ReCip® typically consists of two basins filled with rock aggregate through which wastewater is flowed in series. One basin is full of wastewater and the other is only partially full. Wastewater is alternately pumped between the basins (reciprocated), which exposes biofilm on the aggregate to air and then submerges it, repeatedly creating aerobic and then anoxic conditions. These conditions promote nitrification and denitrification, in addition to removal of organic matter through biodegradation. The present study reports on 149 days of operation of a pilot-scale ReCip® system treating anaerobic lagoon wastewater at a California flush dairy. The resulting removals of wastewater constituents were 94% of total ammonia nitrogen (TAN), 49% of total nitrogen, 56% of five-day carbonaceous biological oxygen demand, and 61% of total suspended solids. A simple mathematical model, which considers influent TAN concentration and temperature, was capable of predicting TAN removal. Preliminary results of air quality emission monitoring indicate releases of nitrous oxide, methane, and carbon dioxide from the basins during system operation. Additional studies are currently underway to further quantify air emissions, test various ReCip® operating conditions, and develop scale-up cost estimates.
33
Ferreira, Santos Melo Ana Elisa. „New approaches for the synthesis of high-performance polyolefins reactor nanocomposites and blends“. Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0032/document.
Annotation:
Malgré les propriétés remarquables de polyéthylène de masse molaire très élevée(UHMWPE), une généralisation de son application est limitée en raison des difficultésrencontrées lors de sa mise en forme, liées au taux d’enchevêtrement important deschaînes.Le but de ce travail est de développer des nanocomposites et des mélanges à base depolyéthylène, par polymérisation in situ. A cet effet, des catalyseurs métallocènes et despost-métallocènes ont été immobilisés par différentes méthodes sur la silice mésoporeuseSBA-15. Le système poreux de ce support, avec des canaux bien définis à l'échellenanométrique, peut entraîner des effets de confinement des chaînes macromoléculaireset/ou permettre un mélange intime des polymères.Le comportement de la polymérisation de l'éthylène par catalyses homogène et supporté,ainsi que les méthodes d'immobilisation utilisées et leur effet sur l'activité depolymérisation et des masses molaires, ont été évalués.Une caractérisation complète des nanocomposites et des mélanges comprenant différentsaspects des matériaux (morphologie, cristallinité et homogénéité) a été réalisée. Lespropriétés thermiques et mécaniques des matériaux finaux ont été également évaluées.D'une manière générale, les nanocomposites à base de polyéthylène et les mélanges enréacteur ont montré des propriétés mécaniques améliorées, en termes de moduled'élasticité, résistance mécanique, ténacité et résistance au fluage, par comparaison avec lespolyéthylènes communs. En traitant la poudre d'UHMWPE par moulage, par compression àhaute pression et au-dessous de sa température de fusion, une augmentation remarquabledes paramètres mécaniques a été obtenue.Les résultats préliminaires sur la préparation de nanocomposites en utilisant desnanocristaux de cellulose ont montré que cette approche est faisable et qu’elle présente unpotentiel de développementDespite the remarkable properties of ultra-high molecular weight polyethylene, itsapplication is limited by the difficulties encountered in conventional melt processing duethe high degree of entanglement of the chains.The aim of this work is to develop polyethylene based nanocomposites and in-reactorblends, by in situ polymerization. For this purpose metallocenes and post-metallocenecatalysts were immobilized by different methods on mesoporous silica SBA-15. The poroussystem of this support, with well-defined channels at the nanometric scale, may causeconfinement effects of macromolecular chains and/or potentiate intimate mixing ofpolymer blends.Ethylene polymerization behavior of the homogeneous and the supported systems alongwith the immobilization methodologies used and their effect on the polymerization activityand polymer molar masses were evaluated.A complete characterization of the nanocomposites and blends comprising different aspectsof the materials properties (morphology, crystallinity and homogeneity) was carried out.The thermal and mechanical properties of the final materials were also evaluated.In a general way the polyethylene based nanocomposites and in-reactor blends showedimproved mechanical properties, in terms of elastic modulus, mechanical strength,toughness and creep resistance, when compared with neat polyethylenes. By processing theUHMWPE powders by compression molding, at high pressure and below its meltingtemperature a remarkable increase of the mechanical parameters was obtained.Preliminary results on the preparation of nanocomposites using cellulose nanowhiskershave shown that this approach is feasible and show potential for further development
34
Rasol, Hepa. „Influence of Potassium on Gasification Performance“. Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-10350.
Annotation:
To release energy from chemically stored energy in the biomass was the new investigation in recent years. Utilizing of biomass for this purpose occur in two different ways, directly by burning (combustion) the biomass and indirectly by pyrolysis process which will convert the biomass to three main products, bio- tar, bio- char and synthetic gas. Biomass contains different amount of inorganic compound, especially alkali metals which causes some diverse impacts on combustion, pyrolysis and gasification process such as corrosion, agglomeration and fouling problems. This project aims to investigate the effect of K2CO3 on the pyrolysis and gasification processes of three different types of fuel; wood pellets, forest residue pellets and synthetic waste pellets at three different temperatures, 750 °C, 850 °C and 900 °C respectively. The purpose of this work to study and clarify the influence of K2CO3 on char yield, tar yield and tar compositions and the gasification rate and the reactivity of different fuels char. The pyrolysis process was carried out in a fluidized bed reactor during 2 minutes and the products were tar, char and synthetic gas. In this project interested in char and tar only. Char yield calculated and the results shows the char yield increase with increasing of [K2CO3]. While the tar analysis carried on GC- MS instrument at HB to study the tar yield and compositions. The results showed that potassium carbonate has not so much effect on tar yield and its composition. The last part was gasified the char in TGA with steam and CO2 as oxidizing media to study the influence of [K2CO3] on gasification rate and the reactivity of char samples at different temperatures. The result showed the [K2CO3] has inhibitory effect on gasification rate and the reactivity.
35
Benda, MaryAnn Alexandra. „Nonlinearity and controller performance for product property control in a gas-phase polyethylene reactor“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0017/MQ52877.pdf.
36
Waata, Christine Lylin. „Coupled neutronics, thermal-hydraulics analysis of a high-performance light-water reactor fuel assembly“. Karlsruhe : FZKA, 2006. http://bibliothek.fzk.de/zb/berichte/FZKA7233.pdf.
37
Waata, Christine Lylin. „Coupled neutronics, thermal hydraulics analysis of a high-performance light water reactor fuel assembly“. Karlsruhe FZKA, 2005. http://bibliothek.fzk.de/zb/berichte/FZKA7233.pdf.
38
Pantano, Michael (Michael Andrew). „Investigation of performance of an ultrasonic flow meter for potential molten salt reactor applications“. Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/111291.
Annotation:
Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, September 2016.Cataloged from PDF version of thesis. "August 2016."
Includes bibliographical references (pages 100-102).
Molten salts for nuclear reactor applications are not a new idea, as these were investigated at Oak Ridge National Lab in the 1960s. However, the past decade or so has seen a large increase in the interest of these, with a variety of designs proposed. The high volumetric heat capacity is of great appeal, as is the low pressure operation with a several hundred degree Celsius margin to boiling. A wide range of passive safety features have also been proposed. However, no matter what the design, there is a need to measure the flow rate of the salt during operation. The nature of the salt greatly complicates the use of a flow meter that must be submerged in the salt. Ultrasonic flow meters have been used for decades with a variety of fluids. These clamp on the outside of the pipe and send an ultrasonic pulse through the pipe from one transducer to another to measure the flow rate. Unfortunately, these have never been used in conjunction with molten salts at the temperatures necessary for nuclear reactor designs. The high temperature of the molten salt presents a problem, as the transducers must be kept cooler. To facilitate this, a thin metal sheet, known as a Wave Injector, was designed to keep the transducer away from the pipe wall and to carry the pulse from the transducer to the pipe. Prior to testing this system on a molten salt facility, it was tested on a water loop to characterize its behavior in a known environment and help inform future design and testing with the molten salt. The bulk of the testing was done in comparing the flow rate measured by the ultrasonic flow meter with that from a reference, electromagnetic flow meter. While the measurements from both agreed well overall, there was significantly better agreement above 7 GPM than below. The ultrasonic flow meter did exhibit good linearity, giving a predictable response for a known change in flow rate. Other testing related to the installation and set-up of the ultrasonic flow meter. Unlike a more traditional flow meter, the ultrasonic flow meter can be configured in a range of ways. It was determined that, as predicted, having the ultrasonic signal take more paths through the fluid produced more precise flow rate data. Additionally, silver was found to be material of choice to go between the piping and the Wave Injector on the molten salt facility, to promote transfer of the pulse from one to the other. These design and configure settings have helped to inform aspects of the molten salt facility, such as tank size. Additionally, testing with and without the Wave Injector provides an anticipation of the spread in data that will be seen on the molten salt facility. Going forward, some additional tests can be done with flowing water to further evaluate configuration options, however the bulk of testing will be with molten salt. Most tests will be similar to those done with the water loop in this study, with either a single path or multipath configuration. Other tests will need to be done to examine the impact of averaging flow rate data on the spread of measurements as well as the loss of temporal resolution. The intended reactor applications should help inform the acceptable resolution in time for safety purposes. Overall, the ultrasonic flow meter performed well and has shown promise with respect to its use as a flow meter for molten salt measurements.
by Michael Pantano.
S.M.
39
Al-Anzi, Bader. „Performance of a novel confined plunging jet reactor incorporating an annular air lift column“. Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/36129.
Annotation:
In this thesis experiments were carried out to achieve the desired objectives of investigating the performance of a novel confined plunging liquid jet reactor incorporating an annular riser. Air entrainment measurements were made using different confining tubes and the induced flow in the annular tube surrounding the confining tube was measured. The oxygen transfer achieved was also determined and compared with other contacting devices. A literature survey regarding the theoretical and experimental work relevant to unconfined and confined systems, air-lift column and mass transfer has been carried out. The experiments include novel equipment utilized to make the lab measurements including air entrainment and novel air-lift column measurements. The theoretical part of the thesis contains a new model derivation to predict the liquid flow rate in the annular riser, which compares well with the experimental measurements. The objective of the first pilot plant experiments is to make air entrainment rate measurements and to investigate the effect of main variables on air entrainment rate. This enables the research to develop a better understanding of the Confined Plunging Liquid Jet Reactor (CPLJR) as an aeration process, of interest of Kuwait Institute for Scientific Research (KISR) and Kuwait, that can be used in various systems such as wastewater treatment as an aerobic activated sludge process, fermentation and gas-liquid reactions.
40
Mongeon, Sébastien. „Active and Passive Mixing for Immiscible Liquid-Liquid Systems: A Performance Evaluation of Novel Micro-Reactors“. Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37089.
Annotation:
Continuous flow reaction using micro-reactors is a valued technology due to its excellent mass and heat transfer performance, reduced reactor volume, handling capacity of hazardous reactions, and many other process intensifications. These intensifications opportunities interest the fine chemicals, pharmaceuticals producers and other multiphase reaction users who currently use batch processes or already use continuous flow. In this thesis, elements of passive and active mixing are investigated for the application of immiscible liquid-liquid systems.
In the first study, the effects of geometrical arrangements of a residence time between mixing units on the interphase mass transfer rates are evaluated with four different immiscible liquid-liquid systems. A presentation of an algorithm for the optimal selection of a reactor and its operating conditions is given in order to enable easy and improved use of one’s micro-reactor.
In the second study, the impact of a secondary pulse flow on interphase mass transfer is investigated. A coil without internal baffles is used as the oscillatory-flow coil reactor with a continuous active mixing source. The best application for the reactor is determined using a comparison to other complementary continuous flow platforms in the toolbox approach.
The novel advancements presented here will help lead new molecular discoveries and connect the laboratory science scale to the process engineering production scale.
41
Jarvis, Adam P. „Design, construction and performance of passive systems for the treatment of mine and spoil heap drainage“. Thesis, University of Newcastle Upon Tyne, 2000. http://hdl.handle.net/10443/428.
Annotation:
Passive treatment systems for mine water pollution remediation require no chemical or energy inputs, and should only incur limited maintenance costs if properly constructed. This thesis investigates two such passive treatment systems that have been installed at sites in County Durham, UK. The overall objectives of the investigation were to improve understanding of the operation of passive systems in order to produce more accurate design guidelines, and to develop a new passive treatment option to complement existing technologies. To put the research into context the causes, impacts and extent of mine water pollution in the UK and overseas are outlined. In addition a detailed and up-to-date review of passive treatment research and development is provided, which highlights areas in which further research is required. At Quaking Houses, County Durham, a full-scale compost wetland has been constructed to treat an acidic and metal-rich discharge from the spoil heap of an abandoned coal mine. Over the 27 month study period the discharge had pH >_ 4, and mean iron, manganese and aluminium concentrations of 5.4 mg/L, 3.6 mg/L and 6.2 mg/L respectively. The unique design and construction of the 440 m2 wetland is described. An examination of the performance of the wetland illustrates that it has yielded significant improvements in water quality since its construction. Mean reductions in acidity, iron and aluminium concentrations are all around 50%. Bacterial sulphate reduction may be an important contaminant removal mechanism, but its proportional significance is unclear. Comparison of the system at Quaking Houses with other wetlands reveals that the mean reduction in acidity in terms of mass removal per unit area (5.01 g/m2/d) is comparatively low. However, it is shown that comparing wetland performance on this basis may be misleading where influent contaminant concentrations are relatively low, because contaminant removal is demonstrably influent concentrationdependent. A first-order removal assessment method of performance may be more appropriate, and on this basis the Quaking Houses wetland performs well when compared to systems in the USA. An algorithm for predicting wetland effluent iron concentrations is derived using a linear multiple regression technique. Time series analysis strongly suggests that some effluent water quality variables (and therefore wetland performance measures) are significantly affected by seasonal climate changes. In particular aluminium and acidity removal rates rise with increasing air temperature. This implies that to meet the same effluent water quality targets passive treatment systems in cold climate locations may need to be larger than equivalent systems in warmer climates. At Kimblesworth, also in County Durham, a pilot-scale passive treatment system has been operated for 4 months. The Kimblesworth discharge is a net-alkaline pumped mine water containing up to 2 mg/L iron and up to 1 mg/L manganese. The novel system at this site was designed to rapidly remove iron by oxidation and accretion of iron to high surface area media. The monitoring programme has revealed the system to be very efficient. Iron concentrations are consistently reduced to < 0.5 mg/L, and removal rates are an order of magnitude greater than in wetland systems. Furthermore, lithium tracer tests reveal that the residence time of water in the reactors is just 5- 10 minutes. The results of this research suggest that the technology could be applied at full-scale. The compost wetland at Quaking Houses and the new reactor at Kimblesworth may well complement each other. The Quaking Houses system generates alkalinity and removes metal contaminants, but effluent water still contains marginally elevated concentrations of iron (mean 2.4 mg/L). The Kimblesworth system is shown to be very effective at rapidly removing low concentrations of iron, and thus could conceivably be used as a polishing unit following a compost wetland such as that at Quaking Houses. Alternatively high surface area media reactors such as those at Kimblesworth could be used to treat discharges in topographically difficult locations, where the installation of a wetland is not feasible.
42
Turner, Joel David. „The performance of a nuclear fuel-matrix material in a sealed CO₂ system“. Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/the-performance-of-a-nuclear-fuelmatrix-material-in-a-sealed-co2-system(caaeee7f-9551-485b-b3dc-fe14e75bcc5a).html.
Annotation:
An advanced concept high temperature reactor (HTR) design has been proposed - The ‘U-Battery’, which utilises a unique sealed coolant loop, and is intended to operate with minimal human oversight. In order to reduce the need for moving parts within the design, CO2 has been selected as a candidate coolant, potentially allowing a naturally circulated system. HTR fuel is held within a semi-graphitic fuel-matrix material, and this has not previously been tested within a CO2 environment. Graphite in CO2 is subject to two oxidation reactions, one thermally driven and one radiolytically. As such, the oxidation performance of fuel-matrix material has been tested within CO2 at both high temperatures and under ionising radiation within a sealed-system. Performance has been compared to that of the Gilsocarbon and NBG-18 nuclear graphite grades. Gilsocarbon is the primary graphite grade used within the currently operating AGR fleet within the UK, and as such is known to have acceptable oxidation performance under reactor conditions. NBG-18 is a modern graphite grade, and is a candidate material for use within the U-Battery. Virgin characterisation of all materials was performed, including measurements of bulk mass and volume, skeletal volumes and surface areas. High-resolution optical microscopy has also been performed and pore size distributions inferred from digital image analysis. All results were seen to agree well with literature values, and the variation between samples has been quanti- fied and found to be < 10% between samples of Gilsocarbon, and < 4% for samples of fuel-matrix and NBG-18. Thermal performance of fuel-matrix material was observed between 600 °C – 1200 °C and seen to be broadly comparable to that of the nuclear graphite grades tested. NBG-18 showed surprisingly poor performance at 600°C, with an oxidation rate of 3×10−4%/min, approximately ten times faster than Gilsocarbon in similar conditions, and three times faster than fuel-matrix material. The radiolytic oxidation performance of fuel-matrix material and NBG-18 has been observed by irradiating sealed quartz ampoules. Ampoules were pressurised with CO2 prior to irradiation, and the pressure after 30 days of irradiation was measured and seen to fall by 50%. Radiolytic oxidation, and the subsequent radiolysis of the reaction product, CO, was seen to cause significant carbonaceous deposition on the internal surfaces of the ampoule and throughout the samples. Due to the short irradiation times available in the present study, an investigation of the microporosity within irradiated samples has been carried out, using nitrogen adsorption and small-angle neutron scattering (SANS). Pore size distributions produced from SANS show the closure of microporosity within NBG-18, most likely as a result of low-temperature neutron irradiation.As a result of this work, CO2 is no longer a candidate coolant for use with the U-Battery design, due to the rapid deposition observed following irradiation.
43
Rogers, Thomas A. „Long-term biocatalyst performance via heuristic and rigorous modeling approaches“. Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37194.
Annotation:
The experiments which are required to directly assess the operational stability of thermostable biocatalysts can be time-consuming, troublesome, and, in the context of industry, expensive. In the present work, we develop and validate two methods for quickly estimating the total turnover number (a useful indicator of lifetime productivity) of a biocatalyst for any desired operating temperature. The first method is a heuristic approach, built upon a complete mathematical derivation from first principles, in which the total turnover number can be calculated from two simple biochemical measurements. The second method relies on a single non-isothermal, continuous-mode experiment in conjunction with mathematical modeling to determine the intrinsic deactivation parameters of the biocatalyst. Both methods provide estimates of the total turnover number which are well within one order of magnitude of the values measured directly via isothermal aging tests and therefore are extremely valuable tools in terms of the amount of experimental time eliminated.
44
Brodeur, David Lester. „A study of US Nuclear Power Boiling Water Reactor, Class IV, operating performance, 1992-1997“. Thesis, Monterey, California. Naval Postgraduate School, 1998. http://hdl.handle.net/10945/9035.
45
Azimi, A. A. „The effects of reactor configuration on the performance of nitrifying activated sludges under transient loadings“. Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233194.
46
Stawicki, Michael A. „Benchmarking of the MIT High Temperature Gas-cooled Reactor TRISO-coated particle fuel performance model“. Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/41273.
Annotation:
Thesis (S.M. and S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2006.Includes bibliographical references.
MIT has developed a Coated Particle Fuel Performance Model to study the behavior of TRISO nuclear fuels. The code, TIMCOAT, is designed to assess the mechanical and chemical condition of populations of coated particles and to determine the failure probability of each of the structural coating layers. With this, the code determines the overall particle failure rate. TIMCOAT represents a significant advancement over earlier codes as it includes a pyrocarbon crack induced particle failure mechanism, which applies probabilistic fracture mechanics. As part of the International Atomic Energy Agency (IAEA) Coordinated Research Program (CRP) on coated particle fuel technology, a code benchmark has been developed by the Idaho National Laboratory (INL). The benchmark includes simple analytic studies and more complex simulations of TRISO particles from past and future experiments. For each study a large variety of particle parameters are specified. This thesis reports TIMCOAT's results from the benchmark study. As this was a blind benchmark, no other results are available for comparison. However, TIMCOAT is able to independently calculate several of the parameters specified by the benchmark, and comparisons are made between results obtained using IAEA parameters and TIMCOAT calculated parameters. The material properties which describe the effects of irradiation on pyrolytic carbon are the focus of the comparison. The rates of irradiation induced creep and swelling calculated by TIMCOAT and the rates provided in the benchmark differed by a factor of two to four in some cases and led to differences in particle failure rate by several orders of magnitude. In addition, varying the uncertainties in these and other parameters was found to have a large impart on the failure probability.
(cont.) It is concluded that accurate modeling of TRISO particles depends on having very high accuracy data describing material properties and a very good understanding of the uncertainties in those measurements.
by Michael A. Stawicki.
S.M.and S.B.
47
Brodeur, David Lester 1963. „A study of US nuclear power boiling water reactor, class IV, operating performance, 1992-1997“. Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/49796.
Annotation:
Thesis (Nucl.E. and S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1998.Includes bibliographical references.
The steady improvement of US Nuclear Utility generation capability observed over the past two decades has recently halted and somewhat degraded. For the industry to resume its upward trend in performance a detailed examination must be performed of current performance and new methods developed to continue the improvement. A detailed study of Boiling Water Reactor, Class IV (BWR/4) performance over the past five years was conducted to gain insight to the nature of lost generation capability and develop a methodology to improve capability. Extensive electronic NRC records were used in conjunction with detailed power plant records and engineering experience at PECO Energy's Limerick Generating Station and Peach Bottom Atomic Power Station for this research. Administrative or regulatory shutdowns within the study dominated the lost generation capability and detracted from the goal of analyzing equipment reliability. Nine of two hundred thirty five shutdowns were therefore limited to maximum impact of 30 days lost generation. Balance of Plant system failures were found to initiate 69% of the occurrences of lost generation capability and account for 59% of the capability loss. The failures of these systems were found to be infrequent events which correlated poorly to the aggregate industry experience. Approximately fifty percent of the forced outages were the result of equipment related failures such as weak design or worn parts with the remaining fifty percent the result of human related failures. Only 19% of the failures were noted to be the result of component age related failures while 31% of the failures were related to poor equipment design. The time frame of forced outages with in operating cycles was additionally reviewed. Failures were found to be more frequent in the early phase of the operating cycle following start up from a refueling and approximately 400 to 550 days after start up. The impact of these failures was not great enough to affect the steady state cumulative capability factor of the aggregate BWR/4 utility achieved after one year of operation. Individual utility sites were found to have opposing strong and weak periods of performance within their operating cycles. The loss of generation capacity taken for planned maintenance outages and on line maintenance for minor equipment problems was not found to have a significant impact on aggregate BWR/4 performance. For plants not involve in lengthy shutdowns, the strongest impacts on cumulative capacity were forced outages, initial start up and coast down. The unpredictable and design nature of system failures necessitates a structured effort to improve the combined performance of all systems at a utility. Balance of Plant systems were found to all have a 25% probability of causing a single forced outage lasting slightly less than 5 days in length. The infrequent nature of significant failures necessitates a broad based communication between utilities to maintain an adequate level of awareness of system vulnerabilities and possible improvements. Two specific sites examined had opposing and repeatable strong and weak cycle performance traits. The unique nature of site performance demonstrates the impact that improved communications between utilities could have on transferring strengths and diminishing weaknesses thus improving overall utility performance.
by David Lester Brodeur.
Nucl.E.and S.M.
48
Sanders, Neil. „The effect of fouling and concentration polarisation on the performance of an enzyme membrane reactor“. Thesis, University of Bath, 1990. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254968.
49
Fedock, John Andrew. „Low temperature polymer electrolyte fuel cell performance degradation“. [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002565.
50
Rahaman, Md Saifur. „Phosphorus recovery from wastewater through struvite crystallization in a fluidized bed reactor : kinetics, hydrodynamics and performance“. Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/38532.
Annotation:
Struvite crystallization from wastewater, using a novel fluidized bed reactor developed at UBC, offers a significant reduction (80—90%) of soluble phosphate from waste streams and generates a product that can be reused as a slow release fertilizer. To implement this green technology at a plant scale, a reactor model that incorporates process kinetics, thermodynamics and the system hydrodynamics, is required. Therefore, the main objectives of this dissertation were to study the struvite precipitation kinetics, thermodynamics, and fluidization characteristics of the struvite crystals bed, and finally, develop a model based on
this information. Both dissolution and precipitation experiments were carried out in a jar test apparatus to study the solubility and precipitation kinetics of struvite. The struvite solubility product, pKsp values were found to vary from 13.43—14.10, for different water and wastewater samples tested at 20°C. Also, a correlation was developed to estimate struvite solubility at different temperatures. In struvite precipitation experiments, the operating conditions of supersaturation, pH, Mg:P ratio, mixing and seeding conditions were varied to identify the effect of those process parameters on the precipitation kinetics. The kinetic rate constant increases with increasing both the supersaturation and Mg:P ratios. Both the mixing energy and seeding rate were found to have minimal effect on ortho-P removal. Detailed experimental and numerical investigations of the fluidization characteristics of struvite crystals were performed. The bed expansion behaviour of mono-sized struvite crystals can be represented reasonably well by the Richardson-Zaki relation and the expansion characteristics of poly-dispersed struvite crystals bed can be predicted by the ‘serial model’. The CFD simulated bed expansion behaviour of the crystals bed was found to be consistent with the experimental results. Also, CFD simulations were capable of capturing the mixing/segregation behavior of a fluidized-bed of multi-particle stnivite crystals.
Finally, a mathematical model was developed by assuming a complete segregation of the bed crystals and liquid movement as plug flow in the reactor. The model predictions provided a reasonably good fit with the experimental results for both P0₄-P and NH₄-N removal. The model predicted mean size of product crystals matched reasonably well with pilot scale experimental results.