IDENTIFICATION OF ELECTROREFINER AND CATHODE PROCESSING FAILURE MODES AND DETERMINATION OF SIGNATURE-SIGNIFICANCE FOR INTEGRATION INTO A SIGNATURE BASED SAFEGUARDS FRAMEWORK FOR PYROPROCESSING

The traditional method of safeguarding nuclear facilities, nuclear material accountancy (NMA), faces many challenges when applied to pyroprocessing facilities. To aid in the safeguarding of these facilities, process monitoring (PM) is being investigated as a complementary method to NMA. PM takes general process data, such as density, current etc., and applies it to safeguards through the use of a statistical framework. Signature Based Safeguards (SBS), a proposed statistical framework for the application of PM techniques, identifies anomalous scenarios and subsequently identifies and detects their respective PM signatures from a system of sensors. This work focuses both on assisting SBS through identifying anomalous scenarios, and on the computer modeling of these failure modes and the PM signatures for them. The anomalous scenarios investigated were mechanical failure modes with potential safeguards-significance as they could lead to the deposition of plutonium and other actinides in the final uranium product ingot. The signatures of these anomalous scenarios were primarily radiation signatures from a coincidence counter that is used to analyze the final ingots. Several different failure modes were identified for both the electrorefiner and the cathode processor. The signatures for these failure modes were then determined by coupling two separate computer models. The first model is a FORTRAN-based electrorefiner code named ERAD capable of modeling the mass transport of metals within an electrorefiner. The second model was an MCNP-based simulation of the Canberra JCC-31 High Level Neutron Coincidence Counter. First, the identified failure modes were simulated by changing ERAD inputs. ERAD calculated an elemental mass composition at the cathode which was then used as the final ingot composition. The final ingot composition was analyzed for single and double neutron coincidence count rates using the MCNP model. The results demonstrate significant radiation signatures for the presence of plutonium as a result of the electrorefiner failure modes. Signatures from cathode processor failure modes were weak and thus warrant future investigation of better detectors for integration into a SBS framework

Reconstructing the Spatial and Temporal Patterns of Daily Life in the 19th Century City: A Historical GIS Approach

In recent years, historians and historical geographers have become interested in the use of GIS to study historical patterns, populations, and phenomena. The result has been the emergence of a new discipline, historical GIS. Despite the growing use of GIS across geography and history, the use of GIS in historical research has been limited largely to visualization of historical records, database management, and simple pattern analysis. This is, in part, due to a lack of accessible research on methodologies and spatial frameworks that outline the integration of both quantitative and qualitative historical sources for use in a GIS environment. The first objective of this dissertation is to develop a comprehensive geospatial research framework for the study of past populations and their environments. The second objective of this dissertation is to apply this framework to the study of daily life in the nineteenth-century city, an important area of scholarship for historical geographers and social historians. Other daily life studies have focused on various experiences of daily life, from domestic duties and child rearing to social norms and the experience of work in early factories. An area that has received little attention in recent years is the daily mobility of individuals as they moved about the ‘walking city’. This dissertation advances our understanding of the diurnal patterns of daily life by recreating the journey to work for thousands of individuals in the city of London, Ontario, and its suburbs in the late nineteenth century. Methodologies are created to capture past populations, their workplaces, and their relationship to the environments they called home. Empirical results outline the relationship between social class, gender, and the journey to work, as well as how social mobility was reflected through the quality of individuals’ residential and neighbourhood environments. The results provide a new perspective on daily mobility, social mobility, and environment in the late nineteenth-century city. Results suggest that individuals who were able to be upwardly socially mobile did so at the expense of substantial increases in their journey to work

Commemorating the Holocaust and Communism: The Politics of Hungarian Public Memory

Nations and nationalists make use of historical narratives in their quests to build unity and achieve other political goals. Those who control memories of the past are often able to affect changes in the future. Hungary is no exception; it is also a particularly historically conscious society with a dark and discontinuous recent past, which is currently being tackled by an increasingly controversial political leadership. This thesis explores this dynamic between power and history by examining public memories of the Holocaust and communism, as represented in the public sphere by museums. It focuses on the narratives told by those with power, and seeks to identify the functions of these stories. What motivates groups to tell which stories and what purpose do these public memories serve? This thesis analyzes the texts and symbolism used, the narratives told, and other characteristics of historical museums. It examines the unique representations of the Holocaust and communism and identifies when memories of the two events converge. These public memories, whether advanced by official or other powerful voices, often present narratives of a continuous Hungarian nation, interrupted by foreign-imposed oppression and victimization

Model atmospheres for massive gas giants with thick clouds: Application to the HR 8799 planets and predictions for future detections

We have generated an extensive new suite of massive giant planet atmosphere models and used it to obtain fits to photometric data for the planets HR 8799b, c, and d. We consider a wide range of cloudy and cloud-free models. The cloudy models incorporate different geometrical and optical thicknesses, modal particle sizes, and metallicities. For each planet and set of cloud parameters, we explore grids in gravity and effective temperature, with which we determine constraints on the planet's mass and age. Our new models yield statistically significant fits to the data, and conclusively confirm that the HR 8799 planets have much thicker clouds than those required to explain data for typical L and T dwarfs. Both models with 1) physically thick forsterite clouds and a 60-micron modal particle size and 2) clouds made of 1 micron-sized pure iron droplets and 1% supersaturation fit the data. Current data are insufficient to accurately constrain the microscopic cloud properties, such as composition and particle size. The range of best-estimated masses for HR 8799b, HR 8799c, and HR 8799d conservatively span 2-12 M_J, 6-13 M_J, and 3-11 M_J, respectively and imply coeval ages between ~10 and ~150 Myr, consistent with previously reported stellar age. The best-fit temperatures and gravities are slightly lower than values obtained by Currie et al. (2011) using even thicker cloud models. Finally, we use these models to predict the near-to-mid IR colors of soon-to-be imaged planets. Our models predict that planet-mass objects follow a locus in some near-to-mid IR color-magnitude diagrams that is clearly separable from the standard L/T dwarf locus for field brown dwarfs.Comment: Accepted for publication in Ap

Angular Differential Imaging: a Powerful High-Contrast Imaging Technique

Angular differential imaging is a high-contrast imaging technique that reduces quasi-static speckle noise and facilitates the detection of nearby companions. A sequence of images is acquired with an altitude/azimuth telescope while the instrument field derotator is switched off. This keeps the instrument and telescope optics aligned and allows the field of view to rotate with respect to the instrument. For each image, a reference PSF is constructed from other appropriately-selected images of the same sequence and subtracted to remove quasi-static PSF structure. All residual images are then rotated to align the field and are combined. Observed performances are reported for Gemini North data. It is shown that quasi-static PSF noise can be reduced by a factor \~5 for each image subtraction. The combination of all residuals then provides an additional gain of the order of the square root of the total number of acquired images. A total speckle noise attenuation of 20-50 is obtained for one-hour long observing sequences compared to a single 30s exposure. A PSF noise attenuation of 100 was achieved for two-hour long sequences of images of Vega, reaching a 5-sigma contrast of 20 magnitudes for separations greater than 8". For a 30-minute long sequence, ADI achieves 30 times better signal-to-noise than a classical observation technique. The ADI technique can be used with currently available instruments to search for ~1MJup exoplanets with orbits of radii between 50 and 300 AU around nearby young stars. The possibility of combining the technique with other high-contrast imaging methods is briefly discussed.Comment: 27 pages, 7 figures, accepted for publication in Ap