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Dissertations / Theses on the topic 'Nuclear Engineering'
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1
Horsfield, Mark Andrew. "Nuclear Magnetic Resonance in petroleum engineering." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334172.
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Poston, Charles Thomas. "Nuclear power plant systems and security a graduate engineering course /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5789.
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Thesis (M.S.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 12, 2008) Includes bibliographical references.
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Tang, Xiao-wu 1972. "Nuclear magnetic resonance microscopy." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9542.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1999.Includes bibliographical references (leaves 96-100).
This thesis describes the design and applications of an improved Nuclear Magnetic Resonance (NMR) microscope, which permits MRI to study small sample sizes ( < 2mm) at high resolution (up to 2[mu]m). The effects of molecular diffusion and local variations in the magnetic susceptibility in NMR microscopy are described, which, along with the intrinsic low sensitivity of NMR, are the fundamental limitations to resolution. Molecular diffusion in the presence of a magnetization grating not only broadens the point spread function but also reduces the signal intensity. The significance of these effects depends strongly on the magnetic field gradient strengths and imaging protocols. A NMR microscope for a standard bore 14.lT magnet was developed, it is equipped with a highly efficient. solenoidal RF coil and three orthogonal gradients with strengths of 1260G / cm for Gz , 760G/cm for Gy , and 410G/cm for Gx at 15A. A modified CTI sequence is presented which incorporates strong pulsed gradients, Ernst angle excitation, CP coherent detection and reduced k-space sampling. It is the optimal pulse sequence for acquiring high-resolution ( < 5[mu]m) NMR images (best signal-to-noise ratio per unit time) when the effect of molecular diffusion is significant. It is demonstrated that this new sequence makes it possible to acquire images with a high resolution of 2[mu]m x 2[mu]m x 8[mu]m within a few hours. A wide variety of images have been acquired using the new microscope, and representative images are presented to demonstrate the potential of NMR microscopy as a new tool in developmental biology research. In particular, used in combination with other biological techniques, NMR microscopy can provide a robust, non-invasive, 3D imaging approach to quantifying changes in structure due for instance to radiative exposure, therapy, and natural growth or genetic modifications.
by Xiao-wu Tang.
Ph.D.
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Metzler, Florian. "Global nuclear power supply chains and the rise of China's nuclear industry." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78494.
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Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 89-95).
China has embarked on a massive expansion of nuclear power that may fundamentally change the global nuclear industry, for better or for worse. Some industry observers argue that the incumbent nuclear power companies are already losing their position of leadership to emergent Chinese actors. Others argue that the growing Chinese nuclear power industry creates more opportunities for all. In this thesis, I discuss Chinese nuclear power development in relation to the global nuclear power industry. I argue that understanding three aspects of the development of China's nuclear industry help understand the opportunities and threats that come with it: (1) common practices of the global nuclear industry in regard to technology transfer and localization (2) different global trends towards deverticalization and integration and (3) idiosyncrasies of the Chinese manufacturing ecosystem that affect global nuclear power supply chains. I argue that Chinese and foreign companies, and policy makers, need to comprehend these principles well as they inform corporate and national strategies, affecting the present and future competitiveness of nuclear power industry actors globally.
by Florian Metzler.
S.M.
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Chen, Cheng. "NUCLEAR QUADRUPLE RESONANCE AND LOW-FIELD NUCLEAR MAGNETIC RESONANCE FOR MATERIALS AUTHENTICATION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1567518073598426.
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Laderman, Sarah (Sarah Jane). "Minimal nuclear deterrence : a nuclear arsenal reduction plan for the United States." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76953.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2012."June 2012." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 39-40).
The global political climate has called for reductions to nuclear arsenals around the world. This thesis researches how potential deep cuts to the United States' large strategic nuclear arsenal would affect its current nuclear deterrence goals. First, case studies on pre-1960 United States, 1964-2012 France, and 1964-2012 China are conducted to understand how a small nuclear arsenal should be constructed in order to prevent nuclear attack from countries with large nuclear arsenals. The lessons learned from these case studies, the current United States deterrence requirements, and the destructive effects from different warheads are then used to propose a potential composition of a small nuclear arsenal for the United States. The proposal consists of only around 500 warheads (in comparison to the current 2,000 the US has on deployment) and achieves United States deterrence goals through its vast destructive capability, variability, and survivability if targeted against in a first nuclear strike.
by Sarah Laderman.
S.B.
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Oparaji, B. "Robust surrogate models for uncertainty quantification and nuclear engineering applications." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3021712/.
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In this thesis, a framework that quantifies the uncertainties introduced when using surrogate models for Uncertainty Quantification is proposed. The proposed framework have been adopted for a variety of Nuclear Engineering problems.
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Murray, Caitlin Lenore. "India's nuclear power program : a study of India's unique approach to nuclear energy." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/41594.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2006.Includes bibliographical references (p. 53-57).
India is in the middle of the biggest expansion of nuclear power in its history, adding 20 GWe in the next 14 years in the form of pressure water reactors and fast breeder reactors. At the same time, the United States is overturning decades of policy in order to resume the export of nuclear materials to India, opening up the possibility of private investors in the Indian nuclear industry for the first time. This is a period of progress and turmoil in India's nuclear power program. This thesis seeks to describe and analyze India's nuclear prospects and to qualitatively assess the system's strengths and weaknesses. Using the inception of the country's nuclear power program as a starting point, this thesis will trace India's nuclear lineage to the present. In the process, it will evaluate what makes the Indian program unique, and why it may not be ideal for India that the United States is finally renewing its offers of a cooperative nuclear alliance.
by Caitlin Lenore Murray.
S.B.
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Kenausis, Luisa R. "North Korea's nuclear weapons : interpreting weapon design progress based on nuclear test data." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112370.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 55-56).
The proliferation of nuclear weapons is a significant global security issue, and it is important to carefully study the nuclear weapons programs of states that are actively engaging in nuclear proliferation. In this thesis, I interpret the seismic and radionuclide data from North Korea's first two nuclear tests in 2006 and 2009, emphasizing the limitations of that data in reaching deterministic conclusions about the precise devices tested by North Korea. I also review the seismological and radiological literatures surrounding a proposed North Korean nuclear test in May 2010, and summarize the process by which that proposal was investigated and rejected. The most recent North Korean nuclear tests, in 2013 and 2016, are reviewed only briefly. It is found here that the technical data available after the North Korean nuclear tests in 2006 and 2009 provide relatively little information about the designs of the devices that were tested. In the case of the 2009 test, the apparent containment of radioactive material from the test could indicate some improvements in the testing process relative to 2006. The explosive yield of North Korea's nuclear tests has generally increased over time, but this trend in yield does not provide clear information about the advances that have been made in the design of North Korean nuclear warheads.
by Luisa R. Kenausis.
S.B.
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Chutri, Mithun. "Eskom's employees perception on nuclear power in accordance with the IRP 2010 Nuclear Energy Plan." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/26879.
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The future role of nuclear power in global sustainable development, and particularly in the development of industrialising countries is contentious; the debate is often highly emotive. The Republic of South Africa's (RSA) progress towards its largest nuclear procurement program is taking place in the midst of changes within the African National Congress (ANC) ruling party, an increase in global demand for uranium and growing energy needs within South Africa. Major nuclear accidents such as Chernobyl or Fukushima have set nuclear power plant security on top of the public agenda. The internalisation of governance through the creation of responsible eco-citizenship is a primary technique to screen perceived risk, which works through the course of public participation. Participation however, must include those that drive the objectives within the nuclear context. Eskom's Koeberg Nuclear Power Station (KNPS) has a workforce of more than 2000 employees. In 2016, the Department of Energy (DOE) had decided that Africa's leading power utility will be the owner operator and procurer of the planned 9.6 Gigawatts (GW) (e) nuclear fleet that is set out in the IRP2010 report. The perceptual impact of this workforce that keeps the country's economic lifeblood moving is often understated, which was the focus of this study. This study had a distinct focus on what Eskom employee's perceptions are with respect to the IRP2010 nuclear new build program. It was limited to the Western Cape Province and included views from divisions that may be involved in the realisation of the nuclear project. It is unique in its context, as very little has been documented on employee perception within RSA's nuclear industry. It is comparative to a public perception survey, which had a distinct focus on nuclear risk. The public's greatest concerns were noted to be corruption, project mismanagement, excessive cost and lack of trust in stakeholders. The outcome of this study discovered similarities with the public perception survey, however here within nuclear safety and compliance to business best practice were greater significant factors. Most respondents had sufficient knowledge and support for RSA's nuclear plans set out in the IRP reports. Dimensions of how perception was created were voted as being heavily dependent on the leadership within the organisation. With this in mind, Eskom employees have indicated that they are more likely to influence the public if they have their leadership's support, and have gone as far as selecting nuclear power over renewable energy to drive towards the country's commitment towards low greenhouse gas (GHG) emissions. So while there may be shades of perceptual similarities between the public and Eskom employees, fundamentally this study revealed that these two bodies do not have the same perception on nuclear power. The study revealed that if Eskom employee's nuclear perception is disregarded and mismanaged, it may delay the realisation of the nuclear new build program in line with IRP 2010 timelines. This is mainly due to the concern of adherence to good corporate governance by Eskom's leadership.
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Ball, John M. "Practical experiments and simulations for nuclear safeguards education." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4896.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on October 23, 2007) Includes bibliographical references.
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Kilic, Arif Nesimi 1963. "A transient model for decomposition and ablation of concrete during a molten core/concrete interaction." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277892.
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A simple approximation for predicting the concrete erosion rate and depth is derived based on heat balance integral method for conduction with the time dependent boundary conditions. The problem is considered a four-region model including separate, moving heat sinks at the boundaries due to endothermic decomposition reactions. Polynomial temperature profiles are assumed and the results are compared to previous experimental data and other analytical solutions. Since the technique provides an approximate temperature distribution on the average, it does not give the real temperature evaluation but provides a simple prediction of the erosion rates in terms of the parameters that are important during the physical phenomena. Because of its simplicity and reliability, the model might be useful of the larger molten core/concrete interaction models.
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Patel, Sunil U. "Nuclear magnetic resonance spectroscopy and ultrasound." Thesis, Aston University, 1989. http://publications.aston.ac.uk/9708/.
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The work described in this thesis is directed to the examination of the hypothesis that ultrasound may be used to perturb molecular motion in the liquid phase. These changes can then be detected by nuclear magnetic resonance (NMR) in spin-lattice and spin-spin relaxation times. The objective being to develop a method capable of reducing the pulsed NMR acquisition times of slowly relaxing nuclei. The thesis describes the theoretical principles underlying both NMR spectroscopy and ultrasonics with particular attention being paid to factors that impinge on testing the above hypothesis. Apparatus has been constructed to enable ultrasound at frequencies between 1 and 10 mega-hertz with a variable power up to 100W/cm-2 to be introduced in the NMR sample. A broadband high frequency generator is used to drive PZT piezo-electric transducer via various transducer to liquid coupling arrangements. A commercial instrument of 20 kilo-hertz has also been employed to test the above hypothesis and also to demonstrate the usefulness of ultrasound in sonochemistry. The latter objective being, detection of radical formation in monomer and polymer ultrasonic degradation. The principle features of the results obtained are: Ultrasonic perturbation of T1 is far smaller for pure liquids than is for mixtures. The effects appear to be greater on protons (1H) than on carbon-13 nuclei (13C) relaxation times. The observed effect of ultrasonics is not due to temperature changes in the sample. As the power applied to the transducer is progressively increased T1 decreases to a minimum and then increases. The T1's of the same nuclei in different functional groups are influenced to different extents by ultrasound. Studies of the 14N resonances from an equimolar mixture of N, N-dimethylformamide and deuterated chloroform with ultrasonic frequencies at 1.115, 6, 6.42 and 10 MHz show that as the frequency is increased the NMR signal to noise ratio decreases to zero at the Larmor frequency of 6.42 MHz and then again rises. This reveals the surprising indication that an effect corresponding to nuclear acoustic saturation in the liquid may be observable. Ultrasonic irradiation of acidified ammonium chloride solution at and around 6.42 MHz appears to cause distinctive changes in the proton-nitrogen J coupling resonance at 89.56 MHz. Ultrasonic irradiation of N, N-dimethylacetamide at 2 KHz using the lowest stable power revealed the onset of coalescence in the proton spectrum. The corresponding effect achieved by direct heating required a temperature rise of approximately 30oC. The effects of low frequency (20 KHz) on relaxation times appear to be nil. Detection of radical formation proved difficult but is still regarded as the principle route for monomer and polymer degradation. The initial hypothesis is considered proven with the results showing significant changes in the mega-hertz region and none at 20 KHz.
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YeÅ, ilyurt Serhat. "Construction and validation of computer-simulation surrogates for engineering design and optimization." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11889.
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Tompot, Randy William. "Engineering design of electron accelerator targets for the commercial production of isotopes." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42612.
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Sun, Phillip Zhe 1975. "Nuclear magnetic resonance microscopy and diffusion." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29996.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003.Includes bibliographical references.
The goal of the work described in this thesis is to develop the methodology and instrumentation for studying neuron physiology and activation in vivo at near cellular resolution. Using biocompatible crosslinked Hemoglobin (xHb) as a contrast agent, we demonstrated partial local oxygen pressure (pO₂) monitoring in vivo with a home-built high resolution microscopy imaging probe. It is one of the most stable microimaging system designed and fully equipped for microscopic fMRI study. This work is an advancement of using MRI to study fundamental neuron science and cell signal pathways in vivo. NMR Microscopy of pancreatic islet of NOD-SCID mice in vitro has shown the feasibility of tracking T-lymphocytes infiltration into islets before the onset of any diabetes symptoms using contrast agents CLIO-Tat. Application of this to in vivo study will not only advance our understanding of the progression IDDM but also help monitor the treatment and prognosis of IDDM patients. Throughout the high resolution imaging studies at high field (14.1 T), a new gradient sequence was developed to suppress the distortion due to the internal fields. This sequence can faithfully measure the displacement propagator in q-space imaging, and provide the proper displacement contrast in k-space imaging. The constant time imaging technique has been used to image a phantom model of a vascular system. It is made up of two glass tubes, filled with solutions of D[sub]y - DTPA and C[sub]uSO₄ respectively and the field mapping showed significant internal field introduced by their susceptibility difference. The new sequence may find applications in clinical Diffusion Tensor Imaging (DTI) and Diffusion Weighted Imaging (DWI).
by Philip Zhe Sun.
Ph.D.
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McCormick, Darryn. "High temperature concrete for nuclear reactors." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/10980.
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Haratyk, Geoffrey. "Nuclear asset shutdown under uncertainty." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/120610.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 197-208).
The restructuring of the power sector that began in the 1990s created acute competition for nuclear power plants. While merchant reactors benefited from this change in the early years, recently they started to retire for economic reasons well before the expiration of their operating licenses. This unexpected wave of premature shutdowns has severe implications for energy and climate policy. It invites us to re-assess the viability and role of nuclear in a transitioning energy sector. The thesis first develops two new tools aimed at measuring nuclear competitiveness and informing retirement strategies: (1) a structural model of electricity markets based on supply and demand equilibrium and (2) a long-term asset valuation framework accounting for stochastic price dynamics and flexible retirement options. We employ these tools to analyze the challenges facing nuclear energy in two countries: the United States and Japan. After evaluating the drivers and likelihood of premature retirements, we discuss a range of technological innovations and regulatory options that could help nuclear bring value to future competitive markets. We show that low natural gas prices and stagnant electricity demand have been responsible for the drop in nuclear plant revenue in the United States. We measure that renewable wind and solar PV impact nuclear operations only for penetration levels above 15% and 30% respectively. We also find that spot price volatility, a feature of competitive markets, defers nuclear retirement decisions rather than precipitates them. In this context, nuclear must adapt. Greater operational flexibility can prevent financial losses in areas where renewables are being deployed on a large scale. In the medium-term, heat storage technologies would protect plants' profitability while enabling deep decarbonization of the energy sector. Finally, a few plants may be able to reach niche markets by diversifying their output beyond electricity. We recognize that the carbon-free attributes of nuclear energy are not valued in competitive markets. Yet, even a moderate price on carbon would save most reactors. If not possible, states may adopt nuclear subsidies to meet their policy objectives. As a last resort, the exercise of a new mothballing license could prevent the irreversible loss of nuclear assets.
by Geoffrey Haratyk.
Ph. D.
19
Stewart, William A. (William Andrew). "A method for estimating tokamak poloidal field coil currents wich incorporates engineering constraints." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/14110.
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Sutharshan, Balendra 1966. "Engineering design of a fission converter-based epithermal beam for neutron capture therapy." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/49671.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1998.Includes bibliographical references.
There is a need for high intensity and low contamination epithermal neutron beams, for boron neutron capture therapy research and for routine treatment if this becomes a successful modality for treating cancers. A fission converter based design for high performance epithermal neutron beam was developed at the Nuclear Reactor Laboratory of the Massachusetts Institute of Technology. This epithermal beam has the capability of delivering a treatment within minutes with negligible background contamination. This thesis deals with the engineering design of this facility. This fission converter based epithermal facility will be installed in the present thermal column and hohlraum of the MITR-II. The fission converter tank, which contains eleven MITR-II fuel elements, was designed with minimum front plate thickness to minimize neutron absorption. The converter tank structural analysis was performed analytically, and numerically with the finite element code ADINA. Three heat removal designs, natural convection, forced convection with bypass channel and simple forced convection, were considered to remove heat from eleven fuel elements in the fission converter tank. For all three designs, steady state and transient analyses were performed. The transient analysis includes loss of flow, loss of flow with shutter failure (converter scram) and loss of coolant. Most of these steady state and transient analyses were performed by both analytically and numerically. The results show that the fuel disruption will not occur during credible and incredible accident scenarios. Three shutters, cadmium shutter, water shutter and mechanical fast acting shutter were designed to control the beam at the patient position. The shutters were designed using the Monte Carlo radiation transport code MCNP. A medical irradiation room was designed for patient irradiation. The shielding computations for the medical room were also carried out with the MCNP. Fuel handling was investigated and proposed two options for refueling, which are similar to the MITR-II refueling.
by Balendra Sutharshan.
Ph.D.
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Yee, Shannon K. "Nuclear Fuel Cycle Modeling Approaches For Recycling And Transmutation Of Spent Nuclear Fuel." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1213905425.
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Holcomb, David Eugene. "Optical fibers in nuclear reactor radiation environments /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487759914759614.
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Abdallah, Ali. "The perception of Nuclear powerin Sweden : How engineering students view it." Thesis, Uppsala universitet, Industriell teknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-335139.
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Nuclear power has been an important part of the electricity generatingin Sweden in almost half a century. However, the use of nuclear powerraises many complex issues such as economy, accident risks, andradioactive waste management and storage. Nuclear power has thereforebeen debated intensively in Sweden as in many other countries since the1970s. Several countries have changed their nuclear policy and starteddecommissioning programs following the nuclear accident in Fukushimaback in 2011. Citizens' support for nuclear power has declined worldwidein last few years, including in Sweden. This study aims to investigatethe perception of nuclear power among engineering students and showsthat the majority of engineering students, who generally are positivetowards technology, have been affected by their surrounding and areagainst nuclear power. Engineering students in general, both supportersand opponents of nuclear power, agree that Sweden should gradually phaseout nuclear power and replace it by renewable energy sources.
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Waltrip, Mather Knight. "Multi-modular nuclear reactor plant simulation and control." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26094.
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Ozga, Deborah Ann. "The principles of nuclear control." Thesis, University of Southampton, 2001. https://eprints.soton.ac.uk/43760/.
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This thesis develops the principles of nuclear control which are derived from control models initially developed in the 1940s, namely, The Acheson-Lilienthal Report, and the Baruch Plan. Authors of these works aspired to create a grand disarmament scheme establishing an international authority to manage nuclear energy and to prevent states from diverting nuclear energy production to nuclear weapon development. They identified principles, which they believed needed to be incorporated in any nuclear control plan, if the plan was to be effective in promoting international security and stability. The thesis then examines control models that were actually established and explores how they diverged from the suggested principles identified previously. In protecting states' economic and political sovereignty, a series of compromises were made on meeting principles of control. Political realities forced states to settle on a national inspection system (the International Atomic Energy Agency Safeguards System) which sought to detect the diversion of nuclear materials from peaceful uses to nuclear weapons. This type system was initially considered by analysts of the Baruch era but was emphatically rejected as having weaknesses that would undermine the system's effectiveness. Although decision makers were aware of the damage that compromises on the principles could have on the control system's effectiveness, they believed some imperfect control system was better than none at all. The thesis shows that departures of the established model from the earlier model weakened control system effectiveness as predicted by Baruch era analysts. This less rigourous adopted approach achieved broad international acceptability, but could not provide sufficient assurances to all parties. As a consequence, some governments took unilateral action to enhance their security in the face of inadequate controls and/or engaged in efforts to strengthen the system. The mechanisms they created incorporated some of the basic nuclear control principles originally identified a half-century earlier but were rejected on political grounds. The thesis sheds light on the difficulties in implementing control and the relevance of these implementation problems for disarmament. It highlights the struggle between states' desires for more credible systems requiring greater sacrifices on national sovereignty and a need for broad adherence to international control demanding less intrusiveness and wider benefits. The thesis reveals a long-term trend that states appear more willing to accept international control measures as globalisation occurs and concludes that the control system is evolving towards incorporating the principles identified in the 1940s that were not included in the established system.
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Landsberg, Judith Patricia. "Nuclear microscopy in biomedical research." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306016.
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Sooriyajeevan, M. J. S. J. "Image filtering in nuclear medicine." Thesis, University of Aberdeen, 1996. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU090122.
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Nuclear medicine images are degraded by blurring caused by the gamma camera system response function and the inherent Poisson noise of radioactivity. Well known digital filters proposed for the restoration of these images have been investigated in this thesis. Particularly, Metz filter and a two-step filter have been extensively studied by the FROC methodology. The effectiveness and practical limitations of the FROC methodology in the assessment of nuclear medicine images have also been investigated. It was observed from the results that the closeness of test patterns to the real clinical cases was a crucial factor for a successful assessment. Therefore, a method to simulate clinical bone scans with focal abnormalities at a given depth has been developed in this thesis. A binormal model is used for the analysis of the FROC and AFROC results. A method has been developed in this thesis to determine the parameters that completely specify the binormal model. Using this method it has been shown in this work that the two-step filter may be useful in detecting focal abnormalities from complicated structures such as bone scans at strict criteria. It also has been observed in this work, that the Metz filter is useful for the detection of focal abnormalities in flat noise fields, but not in complicated structures such as bone scans.
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Lopes, Denise Adorno. "Interação entre precipitação e recristalização em liga de urânio contendo nióbio e zircônio (Mulberry alloy)." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-29102014-171203/.
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No presente trabalho foram estudados os fenômenos de encruamento e, principalmente, transformação de fases, recuperação e recristalização, presentes na liga U-7,5Nb-2,5Zr (Mulberry alloy) e no urânio não ligado. Realizou-se a fusão da liga por dois métodos: plasma (menor massa) e indução (maior massa). A caracterização microestrutural das ligas resultantes nos estados bruto de fundição e homogeneizado (tratado termicamente na região da fase γ seguido de resfriamento rápido em água), assim como do urânio em seu estado inicial, foi realizada com auxílio de várias técnicas complementares de análise microestrutural. No estado gama estabilizado, a liga U-7,5Nb-2,5Zr foi deformada na temperatura ambiente por dois métodos: laminação a frio, dividida em vários estágios (20%, 50%, 60% e 80%), e limagem, sendo o pó resultante de alto grau de deformação. As amostras deformadas foram posteriormente recozidas em tratamentos isócronos (1 hora) e isotérmicos (200ºC, 450ºC e 700ºC). O urânio não ligado foi deformado em aproximadamente 60% e 80% de redução em espessura, e em seguida submetido a tratamentos isócronos (1 hora) e isotérmicos (400ºC e 650ºC). Os fenômenos de encruamento, recuperação, recristalização e transformação de fases foram estudados predominantemente por microscopia óptica, dureza e difração de raios X, com auxílio do método de Rietveld. Adicionalmente, técnicas de análise térmica (dilatometria e calorimetria diferencial) foram utilizadas para acompanhamento da cinética de transformação de fase e energia armazenada na deformação. Com relação à deformação, a liga U-7,5Nb-2,5Zr mostrou ser capaz de sofrer reduções da ordem de 70% na temperatura ambiente, sem necessidade de recozimentos intermediários e com um baixo grau de encruamento. Similarmente, o urânio não ligado mostrou ser capaz de sofrer graus de deformação mais altos na temperatura ambiente, entretanto, este material apresentou alto grau de encruamento e, mesmo após considerável grau de deformação, ainda apresentava muitas heterogeneidades de deformação, como bandas de deformação e maclas. Foi observado que a recristalização do urânio não ligado teve início a aproximadamente 454ºC. Para a liga no estado deformado e supersaturado, a precipitação de fases tende a ocorrer antes da recristalização. Assim, o comportamento desta liga sob aquecimento pós-deformação pode ser resumido da seguinte forma: ~200°C (Recuperação) ---> 300-575°C (Precipitação de fases) ---> 575°C (Recristalização). O rápido aquecimento para temperaturas acima de 650ºC, ou a manutenção desta temperatura por longos tempos, gera uma estrutura γ recristalizada com grãos equiaxiais. Uma estrutura de grãos finos (~8,3µm) foi obtida no recozimento a 700ºC/1h tanto para baixo como para alto grau de deformação. Uma taxa de aquecimento lenta, ou recozimento na faixa de 300-575ºC, gera precipitação da fase antes da recristalização. Consequentemente, a transformação eutetóide γ→α+γ₃ ocorre de modo a herdar a orientação do grão γ deformado, o que pode gerar uma textura de transformação. Na faixa de temperaturas de 575-650ºC ocorre a interação entre os fenômenos de precipitação de fase e recristalização. Em recozimentos a 200ºC foi possível observar a predominância da recuperação para graus de deformação intermediários (60%) e altos (80%), mas para grau de deformação baixo (20%) prevaleceu endurecimento por precipitação da fase α\'\'. Com auxílio da análise em um calorímetro diferencial (DSC) foi observado que a energia armazenada na deformação e liberada durante o processo de recristalização da liga U-7,5Nb-2,5Zr foi de 6,5J/g. Tal valor é relativamente alto se comparado aos metais comuns, o que leva à suposição de que uma linha de discordância no urânio representa uma maior energia. Este fato tem influência direta no processo recristalização. Este experimento demonstrou também que os fenômenos de precipitação de fase e recristalização interagem entre si, com relação à energia disponível para o processo. A textura da liga U-7,5Nb-2,5Zr foi estudada por difração de raios X (DRX) nas condições com fase γ estabilizada (obtida através de fusão, coquilhamento e homogeneização seguida de têmpera) e no estado deformado (laminado a temperatura ambiente). A liga na condição com γ estabilizado apresentou textura moderada com apenas as componentes (023) e (032). Após a deformação de 80%, o material apresentou uma textura de fibra (001)<uvw>, pouco comum nos metais CCC, além da fibra γ (111)<uvw>, com intensidade intermediária.In this work it was studied the phenomena of work hardening, mainly phase transformation, recovery and recrystallization in the U-7.5Nb-2.5Zr alloy (Mulberry alloy) and unalloyed uranium. The alloy was melted by two methods: plasma (smaller mass) and induction (larger mass). Microstructural characterization of the samples in the as-cast and homogenized states (the last one was heat treated in the γ phase region and then quenched in water), as well as uranium in its initial state, was performed using several complementary techniques for microstructural analysis. In the gamma stabilized state, the U-7.5Nb2.5Zr alloy was deformed at room temperature by two methods: cold rolling in several stages (20%, 50%, 60% and 80%), and then filed, resulting in a powder with high degree of deformation. Deformed samples were subsequently annealed by isochronal (1 hour) and isothermal (200°C, 450°C, 700°C) treatments. Unalloyed uranium was deformed by approximately 60% and 80% reduction in thickness, and then subjected to isochronous (1 hour) and isothermal (400°C and 650°C) treatments. The phenomena of work hardening, recovery, recrystallization and phase transformation were studied by optical microscopy, hardness testing and X-ray diffraction, using the Rietveld method. Additionally, thermal analysis techniques (differential calorimetry and dilatometry) were used to measure the kinetics of phase transformation and energy stored during deformation. With regard to deformation, the U-7.5Nb-2.5Zr alloy was reduced of approximately 70% at room temperature without intermediate annealing and with a low degree of work hardening. Similarly, unalloyed uranium was reduced of high degrees of deformation at room temperature. However, this sample showed a higher degree of work hardening, and even after significant deformation still showed lots of inhomogeneities of deformation, such as deformation bands and twins. It was observed that recrystallization of unalloyed uranium started at about 454°C. For the alloy in the supersaturated and deformed states, the phase precipitation tends to occur before recrystallization. Thus, the behavior of this alloy under heat treatments after deformation can be summarized as follows: ~200°C (Recovery) ---> 300-575°C (Phase precipitation) ---> 575°C (Recrystallization). Rapid heating to temperatures above 650°C, or maintain this temperature for a long time, generates a γ recrystallized structure with equiaxed grains. Fine grain structure (~8.3 µm) was obtained for annealing at 700°C/1 h for both lower and higher deformation degrees. Slow heating rate or annealing treatment in the range of 300 to 575ºC, causes precipitation before recrystallization. Consequently, the eutectoid transformation γ→α+γ₃ occurs in order to inherit orientation from the γ deformed grain, which may generate a transformation texture. The interaction between the phenomena of phase precipitation and recrystallization was observed in the temperature range of 575-650°C. At the annealing temperature of 200°C it was possible to observe the predominance of recovery at intermediate (60%) and higher (80%) degrees of deformation, while at lower deformation degree (20%) α phase precipitation hardening has predominated. The results obtained using a differential calorimeter (DSC) showed that the energy stored during deformation and released during the recrystallization of the U-7.5Nb-2.5Zr alloy was 6.5 J/g. That value is relatively high compared to common metals, which leads to the conclusion that dislocation lines in uranium alloys possess higher energy. This fact has a direct influence in the recrystallization process. This experiment also demonstrated that the phenomena of phase precipitation and recrystallization interact with each other with regard to energy available for the process. The texture of the U-7.5Nb-2.5Zr alloy was studied by X-ray diffraction (XRD) in the γ-phase stabilized condition (obtained by melting, casting, homogenization and then quenching) and in deformed state (rolled at room temperature). The first condition generated moderate texture with the components (023) e (032). After 80% of deformation, the samples showed a fiber texture (001)<uvw>, uncommon in the BCC metals, as well the γ fiber (111)<uvw> with intermediate intensity.
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Hodges, Jonathan Stuart. "Engineering coherent control of quantum information in spin systems." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/44781.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.Includes bibliographical references (p. 151-161).
Quantum Information Processing (QIP) promises increased efficiency in computation. A key step in QIP is implementing quantum logic gates by engineering the dynamics of a quantum system. This thesis explores the requirements and methods of coherent control in the context of magnetic resonance for: (i) nuclear spins of small molecules in solution and (ii) nuclear and electron spins in single crystals. The power of QIP is compromised in the presence of decoherence. One method of protecting information from collective decoherence is to limit the quantum states to those respecting the symmetry of the noise. These decoherence-free subspaces (DFS) encode one logical quantum bit (qubit) within multiple physical qubits. In many cases, such as nuclear magnetic resonance (NMR), the control Hamiltonians required for gate engineering leak the information outside the DFS, whereby protection is lost: It is shown how one can still perform universal logic among encoded qubits in the presence of leakage. These ideas are demonstrated on four carbon-13 spins of a small molecule in solution. Liquid phase NMR has shortcomings for QIP, like the lack of strong measurement and low polarization. These two problems can be addressed by moving to solid-state spin systems and incorporating electron spins. If the hyperfine interaction has an anisotropic character, it is proven that the composite system of one electron and N nuclear spins (le-Nn) is completely controllable by addressing only to the electron spin. This 'electron spin actuator' allows for faster gates between the nuclear spins than would be achievable in its absence. In addition, a scheme using logical qubit encodings is proposed for removing the added decoherence due to the electron spin. Lastly, this thesis exemplifies arbitrary gate engineering in a le-ln ensemble solid-sate spin system using a home-built ESR spectrometer designed specifically for engineering high-fidelity quantum control.
by Jonathan Stuart Hodges.
Ph.D.
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Uesako, Daisuke. "STAMP applied to Fukushima Daiichi nuclear disaster and the safety of nuclear power plants in Japan." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107596.
Full textAbstract:
Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, School of Engineering, System Design and Management Program, Engineering and Management Program, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references.
On March 11, 2011, a huge tsunami generated after the Great East Japan Earthquake triggered an extremely severe nuclear accident at the Fukushima Daiichi Nuclear Power Plant. This thesis analyzes why the stakeholders could not prevent the Fukushima Daiichi nuclear disaster, and, with regard to the future nuclear safety in Japan, what the potentially hazardous control actions could be. Because of the complex sociotechnical nature of nuclear power plants, System-Theoretic Accident Model and Processes (STAMP)-specifically, Causal Analysis based on STAMP (CAST) and System-Theoretic Process Analysis (STPA)-is used for these analyses. The CAST process reveals the whole picture of the unsafe control actions by multiple stakeholders, as well as their flawed communication and coordination, which significantly damped the overall control structure for the Fukushima Daiichi Nuclear Power Plant. It becomes clear that all the stakeholders were inadequate to fulfill their safety requirements regarding the safety design, safety management and emergency response. The shared notion of the "Safety Myth," which emerged as an "explanation on safety" for the purpose of promoting the use of nuclear power and was enhanced, among others, by administrative issues such as lack of leadership on nuclear safety, flawed safety culture, lack of resources at the regulatory bodies and bureaucracy, restricted the efforts by the stakeholders to ensure the actual safety against severe accidents or compound nuclear disasters. The STPA process identifies a number of unsafe control actions in the control structure for the safety of nuclear power plants in Japan, the causal scenarios by which these unsafe control actions could occur, and possible safety requirements to prevent these causal scenarios. It is demonstrated that, despite extensive improvements by the stakeholders after the Fukushima Daiichi nuclear disaster including the establishment of a new regulatory body, the "Safety Myth" or administrative issues might still come into play as causal factors, while investment for safety and sound safety culture can be possible safety requirements that subdue these causal factors. Finally, recommendations to strengthen the current safety control structure are developed for some key stakeholders, based on the findings of these analyses.
by Daisuke Uesako.
S.M. in Engineering and Management
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Holt, Matthew. "Issues of scale in nuclear graphite components." Thesis, University of Hull, 2008. http://hydra.hull.ac.uk/resources/hull:1684.
Full textAbstract:
A conceptual model for the determination of the effect of specimen size on the strength of nuclear graphites was developed using abstraction techniques and finite element Analysis (FEA). The model was designed to be able to predict the response of nuclear graphites (primarily IM1-24 graphite) using fixed material properties under defined loading conditions and model constraints. Employing custom written C++ programs, randomly generated microstructural representations of IM1-24 graphite at a number of differing sizes were produced and subsequently had the stresses and strains through the model analysed using ANSYS FEA software. In conjunction with the conceptual modelling, a comprehensive testing programme was designed and developed to gain a data set for the validation of the model outputs. Two types of graphite were selected for the testing programme. Logically, IM1-24 graphite and a control graphite R4340. A large number of varying sizes of specimen were tested to failure under compression, 3-point and 4-point flexural loading and all results recorded and analysed. On completion of both programmes it was found that the modelling programme proved to be successful, in particular, the microstructural response of the virtual material when compared to the testing results. An issue of constant strain inherent in the models due to the loading conditions rendered the numerical results difficult to compare to the testing programme, but the data obtained for the testing programme has expanded the knowledge of the response of IM1-24 graphite at differing scales and loading conditions.
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Li, Qing 1972. "Observer-based fault detection for nuclear reactors." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/30005.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2001.Includes bibliographical references (p. 153-156).
This is a study of fault detection for nuclear reactor systems. Basic concepts are derived from fundamental theories on system observers. Different types of fault- actuator fault, sensor fault, and system dynamics fault can be detected and localized by studying the asymptotic response of an error signal constructed from the system inputs, system outputs, and observer outputs. False alarm and failure to detect a fault are two decision errors when noise is considered. The goal here is to achieve a reasonable compromise. The two types of decision errors can be characterized by their respective first hitting time of a decision threshold. This in turn is dependent on the design of the observer and the decision rule. Costs corresponding to these two types of decision error are defined by cost functions that are in turn constructed based on experience and knowledge of the system operation. A method has been developed in this research to find an optimal design of the observer, the design of a frequency-dependent output filter, and a decision rule that could achieve the desired economic goals. This technique is applied to nuclear reactor systems and simulations are carried out. The one-group linear nuclear reactor model is used in the observer. The system is modeled by a one-group linear model and by a six-group non-linear model. Results show that this fault detection method can not only detect a fault but also localize it at the same time by constructing specially targeted fault detection filters. These fault detection filters are robust against measurement noise and modeling errors.
by Qing Li.
Ph.D.
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Ramírez, Muñoz Patricio D. (Patricio Dario). "Dynamic simulation of nuclear hydrogen production systems." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62733.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2011."September 2010." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 261-265).
Nuclear hydrogen production processes have been proposed as a solution to rising CO 2 emissions and low fuel yields in the production of liquid transportation fuels. In these processes, the heat of a nuclear reactor is used to run the chemical reactions in a hydrogen plant. The resulting system is tightly interconnected and operates at very high temperature and pressure, which can lead to operational disruptions and accidents. For this reason, computational studies validating the safe operation of the system are required by regulatory authorities. In the past, safety studies have been conducted by using legacy codes, such as RELAP and MELCOR, and their focus has been the operation of nuclear power plants. However, traditional legacy codes are not appropriate to simulate nuclear hydrogen production. The simulation of a nuclear reactor itself is already complex because it involves simulating reactor kinetics and transport phenomena. To that complexity, nuclear hydrogen production adds the need to simulate chemical reactions in the hydrogen plant. These chemical reactions cannot be represented easily in legacy codes because these codes lack the flexibility, speed and accuracy required to simulate them. Therefore, only a limited number of studies on the safety of these systems exist. Instead of using legacy codes, this thesis proposes using equation-based simulators developed by the chemical engineering community to model and study the safety of a nuclear hydrogen production plant. Equation-based simulators were designed to be flexible, extensible and fast because they have to simulate a vast range of processes from the chemical industry. Thus, they provide a good platform for the simulation of nuclear hydrogen production systems. This thesis explains the models used for the different parts in the nuclear hydrogen production plant, and then presents the response of this plant model to different accident scenarios. The first contribution of this thesis is a novel equation-based model for the heat transfer loop connecting a nuclear reactor and a hydrogen production plant. This heat transfer loop uses helium as the heat transfer fluid, which makes simulating its behavior difficult because of the need to model gas dynamics. To resolve this, three models for gas dynamics and two set of coupling conditions for boundary variables were tested in JACOBIAN, an equation-based simulator. The three models for gas dynamics in combination with a novel approach to set coupling conditions for boundary variables were able to represent the interesting time scales accurately in transient scenarios. The accuracy and computational speed of these simulations outperformed those produced by a reference model created in RELAP, a legacy code. The second contribution is a model of a nuclear hydrogen production plant using high-temperature steam electrolysis to produce hydrogen. This model was created to study the effect of potential accidents on the nuclear reactor. It included detailed models of the nuclear reactor and heat transfer loop, and a partial model of the electrolysis plant. The nuclear reactor was modeled as a pebble bed modular reactor, which is one of the safest designs available. The reactor was connected to the hydrogen production plant using the heat transfer loop model already developed in this thesis. The hydrogen production plant was partially represented as a steam superheater in the heat transfer loop. The third contribution is the demonstration of the safety characteristics of the nuclear hydrogen production plant by subjecting the plant model to three accident scenarios. The scenarios involved disruptions in the hydrogen plant or in the heat transfer loop, and all of them-directly or indirectly-lead to a loss of heat sink capacity for the nuclear reactor. This resulted in an increase of the nuclear reactor core temperature, which was quickly moderated by the fission power reduction at the fuel pebbles and by the safe design of the nuclear reactor. As a consequence, the maximum temperature reached in the core was always less than the fuel melting point and the reactor was always in a safe condition. The heat transfer loop could suffer the rupture of a pipe in one of the scenarios, and design modifications to address this were suggested. This thesis' results partially prove that nuclear hydrogen production plants could be safe, and simultaneously, that equation-based simulators are good platforms to demonstrate the safety of these plants. Developing these models and tests further will help guarantee the safety of the plant and obtain regulatory and public approval for this new nuclear application.
by Patricio D. Ramírez Muñoz.
Ph.D.
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Parent, Etienne 1977. "Nuclear fuel cycles for mid-century development." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17027.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003.Includes bibliographical references.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
A comparative analysis of nuclear fuel cycles was carried out. Fuel cycles reviewed include: once-through fuel cycles in LWRs, PHWRs, HTGRs, and fast gas cooled breed and burn reactors; single-pass recycle schemes: plutonium recycle in LWRs and direct-use of spent PWR fuel in CANDU reactors (DUPIC); multi-pass recycle schemes: transmutation of transuranics in LWRs, fast reactors, double strata systems, and molten salt reactors. Mass flow calculations for the fuel cycles at equilibrium were carried out based on data available in the open literature, and results were used to compare the performance of the fuel cycles with respect to uranium utilization, waste management, proliferation resistance, and economics. Potential for mid-century deployment was assessed based on these results. Once-through fuel cycles based on solid fuel thermal reactors are found to be the best candidates for mid-century deployment because the substantial increase in electricity costs entailed by reprocessing schemes is unlikely to be justified by the afforded reductions in long-term proliferation and waste management risks. Furthermore, once-through cycles present lower proliferation and waste management risks in the short-term and their inefficient use of uranium is not likely to become an important issue before the middle of the century even under a high growth scenario.
by Etienne Parent.
S.M.
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Kobayashi, Tatsuro 1967. "Prospects for nuclear power in Southeast Asia." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9547.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1999.Includes bibliographical references (p. 165-167).
Southeast Asia needs strong financial and infrastructure bases for continuous development. in the next century. Although the turmoil of the 1997 Asian financial crisis slowed down economic growth the region is recovering gradually, and will need increasing energy supplies in the future. In the electricity sector, which has had to expand more slowly than it did in the 1980s, the main focus has been changing from how to satisfy the growing demand for high reliability to how to cut the cost of electricity. Under these circumstances, we examine the effective role of nuclear power, which can contribute to the stable supply of electricity and still meet the requirement of low emissions. A method of multi-attribute analysis is proposed to assess the feasibility of introducing nuclear power in combination with other generating facilities, such as natural gas, coal, oil and hydro. Capacity expansion plans from the year 2000 through 2020 in Japan Thailand, and Vietnam, which are composed by a technique of dynamic expansion planning, are evaluated on the basis of total costs, emissions, waste and energy security. In addition, the impact of electricity trade in Southeast Asia on the role of nuclear power is examined. This work concludes that nuclear power is compatible with the energy, economic and environmental conditions that may prevail in the region. The factors that promote nuclear power are: its low variable costs, the need for financial stability against unexpected economic disruptions of gas prices low interest rates to finance its capital needs and the limitation on CO2 emissions due to international concerns about global climate change.
by Tatsuro Kobayashi.
S.M.
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Schor, Matthew Jay. "Control of multi-module nuclear reactor stations." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/117458.
Full textAbstract:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE
Bibliography: leaves 95-97.
by Matthew Jay Schor.
M.S.
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Zhang, Yi 1973. "Reliability quantification of nuclear safety-related software." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28367.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2004.Page 242 blank.
Includes bibliographical references (p. 238-241).
The objective of this study is to improve quality and reliability of safety-critical software in the nuclear industry. It is accomplished by focusing on the following two areas: Formulation of a standard extensive integrated software testing strategy for safety-critical software, and Development of systematic test-based statistical software reliability quantification methodologies. The first step to improving the overall performance of software is to develop a comprehensive testing strategy, the gray box testing method. It has incorporated favorable aspects of white box and black box testing techniques. The safety-critical features of the software and feasibility of the methodology are the key drivers in determining the architecture for the testing strategy. Monte Carlo technique is applied to randomly sample inputs based on the probability density function derived from the specification of the given software. Software flowpaths accessed during testing are identified and recorded. Complete nodal coverage testing is achieved by automatic coverage checking. It is guaranteed that the most popular flowpaths of the software are tested.
The second part of the methodology is the quantification of software performance. Two Bayesian based white box reliability estimation methodologies, nodal coverage- based and flowpath coverage-based, are developed. The number of detected errors and the failure-free operations, the objective and subjective knowledge of the given software, and the testing and software structure information are systematically incorporated into both reliability estimation approaches. The concept of two error groups in terms of testability is initiated to better capture reliability features of the given software. The reliability of the tested flowpaths of the software and that of the untested flowpaths can be updated at any point during testing. Overall software reliability is calculated as a weighted average of the tested and untested parts of the software, with the probability of being visited upon next execution as the weight of each part. All of the designed testing and reliability estimation strategies are successfully implemented and automated via various software tools and demonstrated on a typical safety-critical software application.
by Yi Zhang.
Ph.D.
38
Gammon, M. A. "Stress corrosion cracking of nuclear grade steels." Master's thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/21956.
Full textAbstract:
A nuclear grade 316L stainless steel and a 508-111 quenched and tempered pressure vessel steel were studied for their stress corrosion cracking susceptibility. Cylindrical tensile specimens were subjected to slow strain rate testing at 75°C in aerated, aqueous solutions (distiled water with 1000ppm Cl⁻ or SO₄ = ions in solution) in a range of corrosion potentials. The 316L has been examined for sensitization and stress corrosion resistance. This study has shown that the peak degree of sensitization attainable in this material is well within the limits considered as safe by the nuclear power industry. This material is not susceptible to environmentally assisted cracking as long as the potential is kept below the pitting potential for the material. A single instance of intergranular stress corrosion cracking was noted when this material was tested in 1000ppm Cl⁻ solution at 440mV (SHE). Two casts of 508-111 have been examined: 508-A has been tested in the as quenched condition as well as after two tempering heat treatments, while 508-B has been tested in the fully tempered condition only. The mechanical properties of the 508 type materials are strongly influenced by the heat treated condition and mildly influenced by the service environment. In the quenched condition anodic intergranular stress corrosion cracking is severe in the chloride solution and it is argued that the absence of intergranular cracking in the sulphate solution is due to the over aggressiveness of this environment. In all three heat treated conditions loss of ductility is more pronounced in sulphate solutions than in chlorides. Transgranular cleavage is evident in strongly cathodic conditions and this is ascribed to the ingress of hydrogen. The transgranular hydrogen embrittlement seems to be independant of heat treated condition. Rising load tests on fatigue precracked specimens have indicated that environmentally enhanced crack growth of existing defects does not occur for the conditions tested.
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Keyser, Tinus. "Numerical simulation of nuclear reactor isotope depletion." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/28014.
Full textAbstract:
A program was written in Python to simulate nuclide reactions and burnup in a thermal fission reactor numerically. The program focused on the depletion calculations and used a simplified neutron flux equation. Nuclide data like cross-sections and fission products were read in from ENDF format files that have undergone pre-processing. To solve the more than 500 simultaneous differential equations that describe the varying isotopic concentrations, short-lived decay isotopes and their decay chains were identified and solved with a modified Bateman solution and then the long-lived isotopes concentrations were solved with matrix exponentiation. The flux was calculated to keep the heat output of the reactions constant. The simulation calculations were validated by comparing the output of decay chains with known analytical solutions. The output of the reactor burnup simulation was compared to that of ORIGEN (The Oak Ridge National Laboratory Isotope Generation And Depletion Code) for a Light Water Reactor at constant load to a burnup of 33GWd/ton. The output of the simulation was relatively similar to that of ORIGEN, but differed in some marked ways, e.g. plutonium breeding, which suggested that the neutron flux calculations and neutron absorption by U238 was not similarly modelled as in ORIGEN. By slightly adjusting the neutron absorption of U238 in the simulation, the correspondence between the simulation and the reference output was improved.
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Metzler, Florian. "Experiments to investigate phonon-nuclear interactions." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121824.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 103-107).
This thesis presents a series of experiments conducted by the author between 2016 and 2018 that were designed to test for and investigate a proposed phonon-nuclear coupling interaction and an associated nuclear excitation transfer mechanism. Electric and magnetic interactions of phonons with atomic nuclei have been studied for several decades. However, such second-order interactions are too weak to induce nuclear state changes. Hagelstein and Chaudhary recently identified the possibility of a stronger, first-order phonon-nuclear interaction, based on the boost correction associated with the nucleon-nucleon potential for nuclei embedded in a condensed matter environment. Because the newly proposed interaction follows from the relativistic (Dirac) treatment of nucleons, Hagelstein and Chaudhary refer to this interaction as relativistic phonon-nuclear coupling.
Relativistic phonon-nuclear coupling implies the possibility of phonon-mediated nuclear excitation transfer where in the process of absorbing and emitting phonons, energy can transfer from excited state nuclei to nearby ground state nuclei, analogous to widely studied excitation transfer at the atomic and molecular level. To test for and investigate these theoretical conjectures, we prepared samples with a combination of ground state and excited state Fe-57 nuclei (from beta-decaying Co-57) attached to a steel substrate. Samples then underwent treatment by inducing vibrations via ultrasound or mechanical stress. Simultaneously, time histories of radioactive emission were recorded at different locations. Early experiments with vibrations induced at the MHz level via ultrasound transducers yielded negative results and no variations in radioactive emission were observed. However, in conjunction with mechanical stress, deviations from expected emission were observed.
After applying mechanical stress to a sample, we observed a 19% enhancement above expected levels of 14.4 keV gamma emission from Fe-57 and a 17% enhancement above expected levels of Fe K-alpha emission (which to a large extent is driven by internal conversion from the 14.4 keV nuclear transition). The enhancements decayed away with a time constant of about 2.5 days. At the same time, emission on the Sn K-alpha line (driven by fluorescence of Sn in the steel) was consistent with the expected exponential decay of Co-57 at the 1% level, suggesting detector integrity. Similar deviations from expected emission were observed by two additional detectors in different locations. Further experimentation exhibited a high level of reproducibility of the observed effects. By now, evidence for the effects have been seen in seven different detectors and in six different experimental configurations. In some experiments, reductions instead of enhancements can be observed.
Moreover, we observe differences in the ratio of 14.4 keV gamma and Fe K-alpha emissions across experiments. To explain reported observations, we propose that the temporary enhancements and reductions of emission originate from phonon-mediated nuclear excitation transfer and are caused by resulting delocalization and angular anisotropy effects. Delocalization can result from excitation transferring into the steel substrate and across the Co-57/Fe-57 residue. Angular anisotropy can follow from phase coherence at neighboring sites as a result of resonant excitation transfer. Furthermore, observed differences in the incremental emission of 14.4 keV gamma and Fe K-alpha emission suggests that a new channel for internal conversion is opened in off-resonant states present in excitation transfer. We motivate and discuss the conjectured mechanisms as well as alternative candidate explanations and conclude that the latter do not suffice to account for the reported observations.
Finally, we present limitations of this work to date and point at avenues for further research and clarification. Relativistic phonon-nuclear coupling and nuclear excitation transfer have the potential to form new tools in the toolbox of nuclear engineers. The further pursuit of research in this area could lead to the use of phonons in a wide range of applications: for mixing nuclear states; for generating angular anisotropy or inducing beam formation; and potentially for exciting or de-exciting atomic nuclei in applications otherwise reliant on photons. This, in turn, could lead to many nuclear engineering applications becoming more economical as well as less hazardous.
by Florian Metzler.
S.M.
S.M. Massachusetts Institute of Technology, Department of Nuclear Science and Engineering
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Górny, Krzysztof R. "Nuclear Magnetic Resonance studies of high temperature superconductors /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488192960166452.
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Akpa, Belinda Sena Akosua. "Quantitative, chemically-resolved study of chemical engineering systems using nuclear magnetic resonance." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612860.
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Strother, Matthew Brian. "Hydrodynamic analysis of the offshore floating nuclear power plant." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100112.
Full textAbstract:
Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, Engineering Systems Division, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 85-86).
Hydrodynamic analysis of two models of the Offshore Floating Nuclear Plant [91 was conducted. The OFNP-300 and the OFNP-1100 were both exposed to computer simulated sea states in the computer program OrcaFlex: first to sets of monochromatic waves, each consisting of a single frequency and waveheight, and then to Bretschneider and JONSWAP spectra simulating 100-year storms in, respectively, the Gulf of Mexico and the North Sea. Hydrodynamic coefficients for these simulations were obtained using a separate computer program, WAMIT. Both models exhibited satisfactory performance in both heave and pitch. An alternative design of the OFNP-300 was developed and similarly analyzed in attempt to further improve hydrodynamic performance. A catenary mooring system was designed and analyzed for both plant models. The number of chains and the length of each were selected to ensure the mooring systems would withstand, with sufficient margins of safety, the maximum tension produced in a 100-year storm. This analysis was conducted both with all the designed mooring lines intact, and with the worst-case line broken. A lifecycle cost analysis of various mooring systems was conducted in order to minimize the cost of the mooring system while maintaining adequate performance.
by Matthew Brian Strother.
Nav. E.
S.M. in Engineering and Management
44
Jones, Kyle L. "Benchmark Experiments for Natural Convection in Nuclear Fuel Rod Bundles." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/4942.
Full textAbstract:
Natural convection is a phenomenon in which a flow of the fluid surrounding a body is induced by a change in density due to the temperature difference between the body and the fluid. This flow can be highly non-linear and turbulent, generating eddies. The complex interaction between the convective, viscous and buoyant forces requires the use of modern turbulent simulation tools for simulation. The accuracy of these tools, due to non-linearity, is difficult to assess. The present study investigates natural convection in nuclear fuel rod bundles using heated rods to simulate the storage of spent fuel in dry casks as a benchmark for simulation validation. Four heated, aluminum cylinders are instrumented and suspended in a rotatable, open-circuit wind tunnel. Particle Image Velocimetry (PIV) is used to non-obtrusively measure the velocity fields for various heating and flow conditions. The system response quantities (SRQs) and inflow conditions are acquired using PIV for use in validation of Computational Fluid Dynamics (CFD) models. All measurements are reported with uncertainties and are repeated for multiple flow conditions and heating scenarios. The boundary conditions, initial conditions and SRQs are compiled and made available for public use in validating CFD models.
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Cabeche, Dion Tunick. "Water borne transport of high level nuclear waste in very deep borehole disposal of high level nuclear waste." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/76933.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 52).
The purpose of this report is to examine the feasibility of the very deep borehole experiment and to determine if it is a reasonable method of storing high level nuclear waste for an extended period of time. The objective of this thesis is to determine the escape mechanisms of radionuclides and to determine if naturally occurring salinity gradients could counteract this phenomenon. Because of the large dependence on the water density, the relationship between water density and the salinity was measured and agreed with the literature values with a less than 1% difference. The resultant relationship between the density and salinity is a linear relationship with the molality, and dependent upon the number of ions of the dissolved salt (e.g. CaCl₂ contains 3 and NaCl has 2). From the data, it was calculated that within a borehole with a host rock porosity of 10-⁵ Darcy, it would take approximately 10⁵ years for the radionuclides to escape. As the rock porosity decreases, the escape time scale increases, and the escape fraction decreases exponentially. Due to the conservative nature of the calculations, the actual escape timescale would be closer to 106 years and dominated by 1-129 in a reducing atmosphere. The expected borehole salinity values can offset the buoyancy effect due to a 50°C temperature increase.
by Dion Tunick Cabeche.
S.B.
46
Long, Jonathan. "A Safeguards Design Strategy for Domestic Nuclear Materials Processing Facilities." Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/etd/1710.
Full textAbstract:
The outdated and oversized nuclear manufacturing complex within the United States requires its transformation into a smaller, safe, and secure enterprise. Health and safety risks, environmental concerns, and the end of the Cold War have all contributed to this necessity. The events of September 11, 2001, emphasized the protection requirements for nuclear materials within the U.S. as well as abroad.
Current Nuclear Safeguards regulations contain minimal prescriptive requirements relating to the design of new production facilities. Project management and engineering design guides require that design documents contain specific and measureable statements relating to systems requirements. The systems engineering process evaluates alternatives for an effective and integrated solution during project design.
A Safeguards Design Strategy for domestic nuclear materials processing facilities based upon a core "framework" of safeguards regulatory programmatic elements that also use the prescriptive requirements and similar goals of safety, health, and physical security regulations is proposed and justifiable.
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Kane, Susan Christine. "Extra-terrestrial nuclear power stations : transportation and operation." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34444.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2005.Includes bibliographical references (leaves 111-115).
Many challenges exist when considering nuclear power to provide electricity for bases on the Moon or Mars, including launch safety, landing safety, deployment, control, and protecting the astronauts from radiation. Examples from the past provide guidance in these areas but surface operations on another body have never been attempted and rarely studied. This thesis discusses the risks and design considerations for launching, transporting, landing, and operating a nuclear fission reactor on the Moon or Mars. A reference mission and reactor were chosen to facilitate analysis in these areas. Launching a reactor involves meeting environmental and federal regulations. This includes an extensive safety analysis of launch to determine if launch accidents pose a serious risk to the public due to fuel release or inadvertent criticality. The reactor must also be able to survive the launch conditions without damage. Transport mainly involves protecting the reactor from damage from meteoroids. The reactor will then land through propulsive means on the Moon or Mars. Landing a reactor will also require a safety analysis to determine the consequences of a landing accident on the Moon or Mars. On the surface, the reactor must be at a location far enough away from the astronauts to limit radiation exposure to the astronauts from the reactor.
(cont.) Interaction from ground control and astronauts will be necessary to initiate startup, shutdown, and to change the power level of the reactor; however, startup and operation of the reactor must be autonomous due to the communications time lag between Earth and the Moon or Mars. These are significant challenges but all are feasible given the technology and experience in nuclear engineering and astronautics that exits today.
by Susan Christine Kane.
S.M.
48
Sui, Yu 1973. "Identification of performance indicators for nuclear power plants." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/29997.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2001.Includes bibliographical references (p. 160-162).
Performance indicators have been assuming an increasingly important role in the nuclear industry. An integrated methodology is proposed in this research for the identification and validation of performance indicators for assessing and predicting nuclear power plant overall performance (i.e., both economic and safety performance) in a systematic and quantitative way. The methodology consists of four steps: the selection of target sites/plants, the identification and refinement of candidate indicators, the collection of historical operating records of selected indicators, and the identification and evaluation of correlations between selected indicators and plant performance through data analysis. The methodology is centered upon individual plants, using plant-specific operation records to identify and validate plant-specific correlations. It can also be applied to multiple plants and the results from different plants can be compared to identify and analyze commonalities and differences in plant operations across-plant. Case studies of the proposed methodology were performed at three target plants. A list of candidate performance indicators was identified through a sensitivity analysis on a quantitative model of nuclear power plant operation. The list was validated and supplemented through interviews with plant personnel and a refined, plant-specific list was obtained for each target plant. Historical operating records of candidate indicators in the lists were collected from target plants. Data analyses, including correlational analysis, multivariate regression analysis, and lead/lag time analysis, were performed using the historical data collected.
(cont.) The methodology was originally intended for the identification of leading indicators, which can provide advance warnings of deterioration of performance before the direct outcome indicators are affected. A regression-based lead/lag time analysis method was proposed and applied in the case studies to evaluate lead/lag relationships between candidate indicators and plant performance. However, the method did not produce stable and reliable results by using the data currently available at the target plants and was not able to identify leading indicators with certainty. As a result, we shifted the focus of our data analysis to identifying correlations between candidate indicators and plant performance through correlational analysis and multivariate regression analysis. Several findings are noteworthy: (1) Data analysis results were sensitive to the indicators and data points used, mainly due to the small number of data points (30-60) available for use in the analyses; (2) Data analysis results generally agreed with our knowledge and expectation, with a few exceptions; (3) Correlations showed large variations from plant to plant; (4) Correlations varied from time to time at most target plants; (5) The outcome indicators with smoother patterns (e.g., the INPO performance index) tended to correlate better with candidate indicators than the outcome indicators that measured relatively rare events and had sharp changes in their patterns (e.g., unplanned capability loss factor); (6) Work order backlogs stood out as important indicators for all three target plants; ...
by Yu Sui.
Ph.D.
49
Smith, Curtis Lee 1966. "Risk-informed incident management for nuclear power plants." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29998.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2002."September 2002."
Includes bibliographical references (p. 235-244).
Decision making as a part of nuclear power plant operations is a critical, but common, task. Plant management is forced to make decisions that may have safety and economic consequences. Formal decision theory offers the potential for a structured approach capable of taking into account risk-related aspects (plant and worker safety, for instance) and, at the same time, important factors like economics and regulatory requirements. Since power generation involves large capital and operational costs, making the decision process more efficient can lead to significant economical savings. With millions of dollars at stake, it is imperative that operational decisions be made in a logical and consistent fashion. In addition to the monetary concerns, a primary driver for this work is the desire to make defensible decisions. Within a structured organization like a nuclear power plant, a variety of interactions take place between groups of decision makers. These groups are asked to provide guidance on a variety of issues, ranging from complex regulatory requirements to planning maintenance activities of standby equipment. By providing an integrated package for decision making, it is believed that tools like the plant risk assessment can be used in a defensible manner as part of the day-to-day operation of the facility. The goal of this report is to describe a decision methodology for nuclear power plant incidents. Here, incidents are categorized as plant upsets that are not serious challenges to plant safety, but nonetheless require an appropriate response.
(cont.) As part of this decision methodology, risk assessment, worker safety, economics, preferences, and formal decision making models make up the foundation. We describe the construction, analysis heuristics, and inherent uncertainty of these models. From this methodological framework, we developed a prototypical on-line advisory tool that provides decisional advice relevant to incident management. The capabilities of this prototype are discussed along with a demonstration via case studies.
by Curtis Lee Smith.
Ph.D.
50
Xu, Xiao 1966. "Model-based control of a research nuclear reactor." Thesis, The University of Arizona, 1994. http://hdl.handle.net/10150/291765.
Full textAbstract:
The purpose of this paper is to generate a controller to raise the reactor neutronic power from a lower level to a higher level and stabilize it a that level. The dynamic response of research reactors was studied during and after the power transient process. An algorithm for the control process was generated, based on a previously published controller. The inverse-kinetics model-based controller was tested by simulation in order to verify successful completion of the control task, during and after the power transient process. A Kalman filter system was constructed to estimate the state parameters needed by the controller. System dynamic response under different conditions was obtained through simulations. The effects of control performance and system dynamic response of model mismatch between the reactor system and the filter system and of incorrectness of initializations of the filter system were studied. Selection of a filter system with an appropriate Kalman gain matrix was made after conducting several simulation tests. Comparison was made between experimental results obtained from the University of Arizona TRIGA research reactor and simulation results from the computerized simulation systems.