Earthquake safety engineering of nuclear power plant structures poses several challenges to the analyst and designer. These problems are characterized by highly transient and dynamic nature of earthquake induced excitations, random nature of details of support motions (in terms of duration, frequency content, amplitude modulation, multiple components, and spatial variability), nonlinear nature of structural behavior, geometrical complexity of the primary and a large number of secondary systems (such as, for example, piping, rotors, and machine panels), soil-structure interactions, demands on high level of safety expected of these structures, and general paucity of recorded data on strong ground motions appropriate for the given site. Probabilistic methods offer the most rational framework to base design decisions for this class of problems. The work reported in the present thesis belongs to this broad area of research. We focus attention on studying two classes of nuclear power plant components, namely, a pipework in the heat exchanger segment, and, control and safety rod drive mechanism (CSRDM) and investigate their performance by taking into account complicating features such as differential seismic support motions across multiple supports, nonlinearities at support locations, random nature of dynamic loads and uncertainties in system parameters. Response measures include peak responses, reliability against specified performance criterion, measures of uncertainties in response variables of interest. Chapter-1 provides the functional details of nuclear power plant structures that includes reactor assembly and heat transport system assembly, CSRDM, heat transfer piping networks, and nonlinear supporting devices (such as rod, spring, guide supports, limiters, and snubbers). The discussion brings out the structural mechanics issues that need attention while analyzing seismic response of some of these components. Chapter-2 provides a brief review of literature covering the following topics: Monte Carlo simulation based methods for static and dynamic reliability analysis problems, digital simulation of random variables and processes, treatment of non-Gaussianity in simulations, strategies for variance reduction, models for uncertainty in response using limited samples, data based extreme value analysis, studies on multi-supported piping networks under differential seismic inputs and seismic performance of CRDM structures. The study identifies specific issues related to numerical simulation of nonlinear dynamic response of multisupported pipeworks to differential seismic inputs, uncertainty propagation and reliability modeling in seismic response of pipeworks and CSRDM using Monte Carlo simulations with variance reduction, data based extreme value analysis, and uncertainty propagation using limited samples as topics requiring further research. The problems of numerical simulation of nonlinear multisupported piping systems subjected to differential seismic support motions and drop time characterization of CSRDM structure during a seismic event are considered in Chapter-3. It is noted that commercially available professional finite element analysis (FEA) softwares do not offer a direct means to tackle this class of problems. On the other hand, FEA packages are best suited to produce acceptable FE models which take into account the geometrical complexities of the structures. Thus, the reasonable way to move forward would be to develop external interfaces that take advantage of FE modeling capabilities of professional packages and at the same time enable treatment of complexities associated with differential support motions, nonlinearities and axial rigid motions of subsystems as in CSRDM. The work reported in Chapter-3 describes the efforts expended in achieving this objective. Here the given built-up structure is divided in to a set of linear substructures each of which are modeled using FE analysis procedures. The proposed scheme allows for these FE models to reside in professional FE analysis codes. An iterative time domain scheme for modeling the interaction forces between these substructures is discussed. The set of governing equations of motion are developed in terms of normal modes of substructures in their uncoupled states. A suite of benchmark problems are first employed to validate the procedure developed. Subsequently, the earthquake induced dynamic response of CSRDM structure and the pipeline running between IHX and secondary sodium pump in a typical fast breeder reactor is simulated. The algorithm for simulation of dynamic response of CSRDM and multi-supported pipelines under differential support motions developed in Chapter-3 is employed in Chapter-4 to investigate the questions concerning influence of uncertainties in specifying the loads and the system parameters on the system response. Specifically, the study focuses on quantifying uncertainty in system response characteristics based on limited number of Monte Carlo simulations of the response. For this purpose we draw upon an earlier work by Wilks which specifies the number of samples needed to estimate γ th percentile point of a random variable with β level of confidence. We explore in this Chapter, the application of this idea in the analysis of nonlinear, randomly parametered, dynamical systems under stochastic excitations. In Chapter-5 we turn our attention to the modeling of aseismic reliability of the nonlinear pipework under differential support motions and the CSRDM structure. The performance functions considered for the piping structure are in terms of highest displacements and stresses over a specified time durations while for CSRDM, the performance function is in terms of scram time being less than a specified time duration. We tackle the first problem by using theory of data based extreme value analysis while the second problem is addressed using an adaptive importance sampling strategy. The contributions here pertain to the exploration of data based extreme values analysis as applied to an industrial scale structure and improvisation of algorithmic modifications in the development of adaptive importance sampling density functions. This improvisation consists of selection of sampling points as a judicious mix of points from both safe and unsafe regions. This is shown to reduce the strong correlations that otherwise would be present if samples are taken only from the unsafe region. These studies demonstrate how Monte Carlo simulations with limited samples can be utilized to draw useful conclusions on structural reliability. Chapter-6 summarizes the main contributions made in the thesis and makes a few suggestions for further research. There are five annexures in the thesis. Annexure-1 contains listing of Matlab m-files used for solving illustrative problems in Chapter-2. The details of FE modeling of multisupported system under differential support motions and the details of substructuring scheme used in modeling of such systems with local nonlinearities are provide in Annexure-2. The details of material and geometry of CSRDM structure are provided in Annexure-3. Annexure-4 summarizes the main details of hypothesis tests used in data based extreme value analysis. The algorithms used for converting response spectra into compatible power spectral density functions are described in Annexure-5.

The thesis deals with the relationship between ecology and law in nuclear energy and the possible impact on the environment. The first part briefly summarizes the most important historical approaches to ecology and describes environmental law in the Czech Republic and the EU. The next section is focused on law in the area of construction and operation of nuclear power plants in the Czech Republic and the EU. The fourth chapter deals with operation of nuclear power plant Temelín and assessment the legislation. The fifth chapter is dedicated to various forms of longstanding conflict between the Czech Republic and Austria.

Orientador: Bento Rodrigues de Pontes Junior / Banca: Marcio Antonio Bazani / Banca: Andre Luiz Andreoli / Resumo: Quatro configurações de circuito elétrico são estudadas como opções de ligação em dispositivos eletromecânicos: puramente resistivo, RL em série, RLC em série e RLC em série com indutância de variação não linear. Respostas em frequência, diagramas de bifurcação, históricos no tempo, planos de fase, mapas de Poincaré e espectros de frequência são utilizados nas análises. Os três circuitos lineares explorados na dissertação revelam algumas diferenças em termos da transmissibilidade de deslocamento. O sistema com circuito puramente resistivo tem as mesmas características de um sistema puramente mecânico e viscosamente amortecido, mas a resistência elétrica e o fator de amortecimento viscoso se relacionam de forma inversamente proporcional. As respostas dos circuitos RL e RLC, ambos em série, apresentam aspectos mais comportados. A principal diferença entre os sistemas com circuitos RL e RLC em série está principalmente na transmissibilidade para baixas frequências. Embora com uma pequena diferença, a transmissibilidade do sistema com circuito RLC é menor do que a do sistema com circuito RL, para baixas frequências. Para o sistema não linear, nas respostas em frequência e diagramas de bifurcação percebem-se regiões de resposta desordenada para valores baixos de resistência elétrica em determinadas faixas de frequência. Com a análise das respostas, notam-se as presenças dos comportamentos dinâmicos periódico, quasi-periódico e caótico. Para valores baixos de resistência elétrica, ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Four configurations of electrical circuit are studied as options of electromechanical devices: purely resistive, RL in series, RLC in series e RLC in series with nonlinear inductance. Frequency responses, bifurcation diagrams, time series, phase plane, Poincaré maps and frequency spectrum are used in analysis. The three linear circuits explored in this dissertation reveal some differences in terms of displacement transmissibility. The system with purely resistive circuit has the same characteristics of a purely viscous damped, but the electrical resistance and the damping factor are inversely proportional. Responses of circuits RL and RLC, both in series, present behaving aspects. The main difference between the systems with RL and RLC circuits is related to the transmissibility for low frequencies. Although with a small difference, the transmissibility of RLC circuit system is smaller than the RL circuit system, for low frequencies. For the nonlinear system, it is possible to perceive disordered response regions for small values of electrical resistance on certain frequency bands. After response analisys, it is noted the presence of periodic, quasi-periodic and chaotic behaviors. For small values of electrical resistance, the choice of capacitance value is very important to determine the type of the dynamic behavior. Small differences of the capacitance values mean significant changes in the system dynamics. It is not rare that even inside the tolerance of electrical compone... (Complete abstract click electronic access below) / Mestre

L'augmentation de la contribution des énergies renouvelables (solaire ou éolien) et une évolution majeure du parc électrique français et s'inscrit dans le cadre de la transition énergétique. Il est prévu que la part de ces énergies dans le mix passe de 6% actuellement à 30% d'ici à 2030. Cette augmentation en revanche laisse entrevoir d'importants déséquilibres entre l'offre et la demande, et les autres moyens de production, l'énergie nucléaire en tête, devront donc s'adapter. Ce travail vise à augmenter la disponibilité de suivi de charge des centrales, en améliorant leur pilotage durant tout le cycle d'exploitation. Parmi l'ensemble des réacteurs du parc nucléaire français, les réacteurs à eau pressurisées d'une puissance électrique de $1300$ MW sont choisis en raison de leur capacité de suivi de charge déjà accrue. Dans un premier temps, un modèle multi-physique et de type simulateur de la centrale est développé, permettant de prendre en arguments les paramètres principaux des barres de commande, et permettant de déterminer en quelques dizaines de minutes de calcul, les critères d'intérêt dont le premier est en lien avec le diagramme de pilotage et le second avec le volume d'effluents. Le problème d'optimisation est alors résolu grâce à des algorithmes évolutionnaires parallèles asynchronesde type maître-esclave, et les mode de pilotage obtenus sont commentés. / The increase of the renewable energies contribution (as wind farms, solar energy) is a major issue in the actual context of energetic transition. The part of intermittent renewable energies is indeed forecast to be around 30% of the total production in 2030, against 6% today. On the other hand, their intermittent production may lead to an important imbalance between production and consumption. Consequently, the other ways of power production must adapt to those variations, especially nuclear energy which is the most important in France. This work aims at increasing the availability of thepower plants to load-follow, by optimizing their manageability all along their operation cycle. Among the French nuclear fleet, the pressurized water reactors(PWR) producing $1300$ electrical MW and operated in the "G" mode are considered as they show the higher capability to load-follow. In a first step, a multi-physics PWR model is designed taking as inputs the main parameters of the control rods, and computing in few minutes the criteria of interest whichare linked to the control diagram and to the effluents volume. The optimization problem which consists in minimizing those two values of interest is then solved thanks to a parallel asynchronous master-worker evolutionary algorithm. Finally, the efficient operating modes are discussed.

How people perceive risk or threats is important to many disciplines that seek to assist policy makers in developing policies, regulations and laws. Using the previous work of Slovic et al. (Fischhoff, Slovic, Lichtenstein, Read and Combs, 2000; Slovic P., 1992; Slovic, Fischhoff, and Lichtenstein, 2000) in development of the psychometric paradigm, a sample of residents (n=600) from a region with a large number of nuclear reactors was surveyed. The question set was expanded to include demographic questions to determine if they impact risk perception. Two aspects of risk perception were examined, perception of overall risk and perception of riskiness along specific dimensions of concern identified previously in the literature. For both risk and riskiness, respondents’ perceptions of nuclear power were compared to three other perceptions of technologies including use of modern farming methods using chemicals, railroad transportation and coal-generated electricity. The recent increase in public concern about nuclear power following the meltdowns at the Fukushima Dai-ichi nuclear power plant led to the expectation that nuclear power would be rated higher in overall risk and riskiness than the other three technologies consistent with Slovic’s earlier work on risk perception. This expectation was generally supported although respondents tended to perceive modern farming methods using chemical as similar in overall risk and riskiness to nuclear power. The research specifically tested five hypotheses concerning the impact of five demographic factors: gender, race, income, education and political orientation on the overall perception of risk and riskiness. Subsequent analysis using analysis of variance and linear regression found that select demographics only explained 2% of the risk perception for nuclear power generation.

Bibliography: pages 112-138. / The large volume of seawater used for cooling at Koeberg Nuclear Power Station contains many planktonic organisms which are exposed to heat, chlorine and physical stress during their passage through the system. Phytoplankton biomass, measured as chlorophyll a, was reduced by an average of 55.32% due to entrainment, and productivity was decreased by 38.30% on average, mainly due to chlorination. Zooplankton mortality averaged 22.34% for all species and 30.52% for copepods, the dominant group. The copepod Paracartia africana was used in laboratory experiments designed to simulate entrainment. Latent mortality was monitored up to 60 hours after a 30-minute application of stress factors (physical stress was not simulated), and approximately 75% of the total mortality occurred within the 30-minute period. Male Paracartia experienced higher mortalities than females. Extrapolation of these results predicts an overall entrainment mortality (including latent mortality) of 40% for copepods and 29.04% for total zooplankton, although the latter cannot be substantiated. Plankton entrainment at Koeberg was not considered to be overly detrimental to the marine environment because of the very localised area affected, rapid dispersion of heat and chlorine, rapid regeneration times of phytoplankton and some zooplankton, low abundance of commercially important species and potential recruitment from the surrounding productive Benguela upwelling region.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: Ref 1-Ref 7. / by Walter Herbert Strohmayer. / Ph.D.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第17796号 / エネ博第279号 / 新制||エネ||58(附属図書館) / 30603 / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 下田 宏, 教授 手塚 哲央, 教授 釜江 克宏 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

With the growing capacity of renewable energy production sources, nuclear energy, once a mainstay of power generation, faces challenges due to its limited adaptability to fluctuating energy demands. This inherent rigidity makes it less desirable than the more flexible renewable sources. However, integrating thermal energy storage (TES) systems offers a promising avenue, enabling nuclear power plants (NPPs) to enhance their operational flexibility and remain competitive in an evolving renewable market. A comprehensive ranking methodology has been introduced, delineating the criteria and processes to determine the most synergistic TES/NPP design couplings. This methodology considers the unique characteristics of both current and prospective reactor fleets, ensuring broad applicability across various nuclear technologies. Economic analysis further supports the case for TES integration. Findings indicate that when equipped with TES systems, NPPs can remain price competitive, even with carbon-neutral alternatives like solar power generation. A lab-scale TES system was meticulously designed and constructed to validate these theoretical propositions. For its control, the Python GEKKO model predictive control (MPC) was employed, a decision influenced by the proven efficacy of GEKKO in managing complex systems. Tests conclusively demonstrated the feasibility and efficiency of using GEKKO for MPC of TES systems. A novel methodology for the MPC of a RELAP5-3D input deck has been proposed and elaborated upon. This methodology was rigorously tested at two distinct scales. The initial focus was on a thermal-hydraulic model of the lab-scale TES system. Subsequent efforts scaled up to control a more intricate thermal-hydraulic model, representing a small modular reactor (SMR) paired with an oil-based TES system. In both scenarios, GEKKO exhibited exemplary performance, controlling the RELAP5-3D models with precision and ensuring they met the stipulated demand parameters. The research underscores the potential of RELAP5-3D MPC in streamlining the licensing process for TES systems intended for NPP coupling. This approach could eliminate the need for expensive and time-consuming experiments, paving the way for more efficient and cost-effective nuclear energy solutions.

The problem of unit commitment in an electric utility system is analyzed. The types of generating units considered include nuclear-steam, fossil-steam, thermalpeaking, conventional and pumped-storage hydro. The large problem of generating unit commitment, due to the inclusion of the nuclear unit, is decomposed into two stages. In the first stage, the relatively stable nuclear generation is optimized with respect to the generation from the large fossil-steam unit. Hourly generation levels for all the units in the system are determined in the second stage. AS a result of considering the startup-shutdown cost, the objective function has a fixed charge component in addition to first and second degree polynomials. Representation of the minimum turndown level and minimum Shutdown duration of the generator necessitates the use of O-1 variables along with continuous variables. The solution methodology presented here, applying an extension of the Lambda-Separable Programming, can handle these requirements efficiently. Application of the algorithm results in a minimum-cost generation schedule for all units in the system. Optimum generation levels of energy limited units are determined without using a preselected unit commitment order. The effect of startup-shutdown costs on the number of hours a Plant should operate is established. The cost and benefit of spent nuclear fuel reprocessing is analyzed and the effect of uranium prices on it (reprocessing) is shown. The model is tested using a sample system of six generating units. Hourly generation schedules, includig purchase and sale, are determined for two one-week periods while the nuclear generation is optimized for an entire year. / Ph. D.