Modeling Integral Fuel Burnable Absorbers Using the Method of Characteristics

Modern core designs that utilize Westinghouse fuel technology employ the use of Integral Fuel Burnable Absorbers (IFBA) that consists of very thin coatings of boron absorber material on the fuel pellets. While IFBA has proven to be an effective burnable absorber, it does present a neutronics modeling challenge. The difficulty of modeling IFBA using the Method of Characteristics (MOC) transport method is well known, and arises from the fact that IFBA is a very small, but also very important, region in nuclear fuel. Experience in modeling IFBA at the pin cell and single assembly lattice level requires a decrease in the MOC ray spacing leading to substantial increases in computation times. This would represent a significant computational challenge for modeling cores containing IFBA with new methods that use full 2D planar MOC calculations, such as that being developed for the Consortium for Advanced Simulation of Light Water Reactors (CASL) Virtual Environment for Reactor Applications (VERA). An investigation of modeling IFBA using MOC was performed to address concerns about accurately modeling IFBA. The accuracy of modeling IFBA using MOC at various ray spacings was examined for different problems using the Michigan Parallel Analysis based on Characteristic Tracing (MPACT) MOC code. For a single 2D IFBA pin cell, there is an extreme dependence on ray spacing for accurate results. This dependence was reduced when a 2D assembly containing IFBA was modeled. An AP1000® full core 2D midplane was modeled, and the effect of ray spacing on accuracy was much less drastic. The accuracy assessments were based both on the eigenvalue and pin power differences when compared to a high fidelity Monte Carlo calculation of the same model. The effect of volume weighting the IFBA material and then smearing it into neighboring regions was examined, and was found to be a less accurate method for modeling IFBA. Depletion cases of the AP1000 model were run to determine the impact of IFBA on the life of the core. It was found that standard ray spacing and step sizes are sufficient for accurately performing full core depletion calculations, but special care is needed for problems of smaller scale

WORM - A NEW OPEN ROAD LINE SOURCE MODEL FOR LOW WIND SPEED CONDITIONS

Emission from road traffic constitutes one of the most important sources of air pollution in urban areas. This paper describes a newly developed air pollution dispersion model for open roads and highways called WORM (Weak Wind Open Road Model), and give some results using this model during low wind speed and (strongly) stable atmospheric conditions at Nordbysletta in Norway, during a 3-4 months period in the winter/spring of 2002

Beyond the Problem Novel: Robert Cormier\u27s Vision and the World of Adolescent Tragedy

Robert Cormier is the premier writer for adolescents in the United States according to The Handbook of American Popular Literature and dozens of literary critics. Although his novels have won numerous awards from the American Library Association (ALA), his novels have also generated controversy from critics who believe his novels are excessively dark and disturbing. Adolescents in Robert Cormier\u27s world are by no means the average teenagers one may expect to find at a local high school. Instead, the adolescent world is shown to be more complex and dangerous, where evil preys on the good, where loneliness and isolation are not occasional occurrences but commonplace, and where anyone who dares to be different is doomed to failure. Cormier\u27s fiction suggests a nihilistic view of society and also implies a dystopia, with almost every present force (government, schools, and religion) mounting together to crush caring individuals. Cormier shows even those who are in power and control (antagonists) find no more happiness than their victims. While Cormier\u27s adolescent novels (which include The Chocolate War, I am the Cheese, The Bumblebee Flies Anyway, Beyond the Chocolate War, We All Fall Down, Tunes for Bears to Dance to, In the Middle of the Night, and Tenderness) belong to the problem novel sub-genre of realistic fiction, they also philosophically differ from the typical problem novel, as represented by such writers as Avi, Judy Blume, Glendon Swarthout, and Paul Zindel. It helps to understand Cormier\u27s fiction by placing it in the context of naturalism, which emphasizes the impotence of individuals because of forces within nature and society. Cormier\u27s vision of adolescents is unusual within the context of adolescent literature because it seems to undermine the concept of the individual, showing adolescents as unable to escape from the problems that encompass them, in part because the problems are difficult, but mainly because the culture of adolescents in conjunction with adult culture ultimately punishes those who attempt to be different, unique, or (especially) good. Cormier\u27s world is one devoid of hope, which contradicts the setting of most problem novels. Additionally, Cormier\u27s novels undermine a common theme in adolescent literature, the rite of passage that develops teens into adults. Instead of treating adolescence as a rite of passage, Cormier shows it to be a period where no transition is needed or can occur since both adults and teenagers are shown to be equally brutal to people who wish to be good or independent. Finally, Cormier\u27s intense focus on characterization makes him unique from most problem novel authors, which usually focus on the problems instead of the characters or relationships. Cormier seems to hint that the problems that surround his characters are arbitrary, and most of the actual harm (both physical and psychological) that occurs to adolescents who try to be different from their peers come from the majority of seemingly ordinary adolescents who are shown to be brutal to anyone who wishes or dares to be different. Thus, I conclude that Cormier exposes the dark side of human nature, and his vision of the adolescent world is one where evil triumphs over good and where individuals who dare disturb the universe are crushed

Low-Order Multiphysics Coupling Techniques for Nuclear Reactor Applications

The accurate modeling and simulation of nuclear reactor designs depends greatly on the ability to couple differing sets of physics together. Current coupling techniques most often use a fixed-point, or Picard, iteration scheme in which each set of physics is solved separately, and the resulting solutions are passed between each solver. In the work presented here, two different coupling techniques are investigated: a Jacobian-Free Newton-Krylov (JFNK) approach and a new methodology called Coarse Mesh Finite Difference Coupling (CMFD-Coupling). What both of these techniques have in common is that they are applied to the low-order CMFD system of equations. This allows for the multiphysics feedback effects to be captured on the low-order system without having to perform a neutron transport solve.The JFNK and CMFD-Coupling approaches were implemented in the MPACT (Michigan Parallel Analysis based on Characteristic Tracing) neutron transport code, which is being developed for the Consortium for Advanced Simulation of Light Water Reactors (CASL). These methods were tested on a wide range of practical reactor physics problems, from a 2D pin cell to a massively parallel 3D full core problem. Initially, JFNK was implemented only as an eigenvalue solver without any feedback enabled. However this led to greatly increased runtimes without any obvious benefit. When multiphysics problems were investigated with both JFNK and CMFD-Coupling, it was concluded that CMFD-Coupling outperformed JFNK in terms of both accuracy and runtime for every problem. When applied to large full core problems with multiple sources of strong feedback enabled, CMFD-Coupling reduced the overall number of transport sweeps required for convergence

Coping with High-Priced Corn

Feed costs represent 50 to 70% of livestock production expenses and are a critical component of livestock profitability. In the Upper Midwest and Upper Great Plains, corn grain is a primary source of energy in livestock diets. Consequently, as the price of corn escalates, so does the cost of feeding livestock. But cost isn’t all: you also must address dietary and management considerations when coping with increased corn prices

Design of Fault Tolerant Control systems

This research designs a Fault Tolerant Control (FTC) approach that compensates for both actuator and sensor faults by using multiple observers. This method is shown to work for both linear time-variant and linear time-invariant systems. This work takes advantage of sensor redundancy to compensate for sensor faults. A method to calculate the rank of available sensor redundancy is developed to determine how many independent sensors can fail without losing observability. This rank is the upper bound on the number of simultaneous sensor failures that the system can tolerate. Based on this rank, a series of reduced order Kalman observers are created to remove sensors presumed faulty from the internal feedback of the estimators. Actuator redundancy is examined as a potential way to compensate for actuator faults. A method to calculate the available actuator redundancy is designed. This redundancy would allow for the correction of partial and full actuator failures, but few systems exhibit sufficient actuator redundancy. Actuator faults are instead tolerated by replacing the Kalman estimators with Augmented State Observers (ASO). The ASO adds estimates of the actuator faults as additional states of the system in order to isolate and estimate the actuator faults. Then a supervisor is designed to select the observer that correctly identifies the sensor fault set. From that observer, the supervisor collects state estimates and calculates estimates of the sensors and faults. These estimates are then used in feedback with a controller that performs pole placement on the original system

The Data Sprint Approach: Exploring the field of Digital Humanities through Amazon’s Application Programming Interface

This paper documents the results of an intensive "data sprint" method for undertaking data and algorithmic work using application programming interfaces (APIs), which took place during the Digital Method Initiative 2013 Winter School at the University of Amsterdam. During this data sprint, we developed a method to map the fields of Digital Humanities and Electronic Literature based on title recommendations from the largest online bookseller, Amazon, by retrieving similar purchased items from the Amazon API. A first step shows the overall Amazon recommendation network for Digital Humanities and allows us to detect clusters, aligned fields and bridging books. In a second step we looked into four country-specific Amazon stores (Amazon.com, Amazon.co.uk, Amazon.fr and Amazon.de) to investigate the specificities of the Digital Humanities in these four countries. The third step is a network of all books suggested for the Electronic Literature field in the four Amazon stores we searched, which offers a comparison to the field of Digital Humanities.publishedVersio

Association of West Nile virus illness and urban landscapes in Chicago and Detroit

BACKGROUND: West Nile virus infection in humans in urban areas of the Midwestern United States has exhibited strong spatial clustering during epidemic years. We derived urban landscape classes from the physical and socio-economic factors hypothesized to be associated with West Nile Virus (WNV) transmission and compared those to human cases of illness in 2002 in Chicago and Detroit. The objectives were to improve understanding of human exposure to virus-infected mosquitoes in the urban context, and to assess the degree to which environmental factors found to be important in Chicago were also found in Detroit. RESULTS: Five urban classes that partitioned the urban space were developed for each city region. The classes had many similarities in the two settings. In both regions, the WNV case rate was considerably higher in the urban class associated with the Inner Suburbs, where 1940–1960 era housing dominates, vegetation cover is moderate, and population density is moderate. The land cover mapping approach played an important role in the successful and consistent classification of the urban areas. CONCLUSION: The analysis demonstrates how urban form and past land use decisions can influence transmission of a vector-borne virus. In addition, the results are helpful to develop hypotheses regarding urban landscape features and WNV transmission, they provide a structured method to stratify the urban areas to locate representative field study sites specifically for WNV, and this analysis contributes to the question of how the urban environment affects human health

Towards a framework for corporate disclosure of circular economy : Company perspectives and recommendations

Circular economy (CE) is becoming an increasingly mandatory material issue within corporate sustainability reporting, however, what remains unaddressed within literature are the perspectives and capacities of the companies which must soon adapt to meet the evolving reporting requirements. This research aims to capture insights from companies engaged with CE in order to develop recommendations that support the integration of CE within corporate sustainability reports. To do this, a series of semi-structured interviews and focus groups were conducted with companies operating in Italy or the Netherlands, not limited by sector. The results provide a list of challenges experienced-and benefits gained-by companies from externally communicating CE. Companies are urged to consider not only risks associated with staying in the linear economy but also those associated with the implementation of new circular practices, to communicate potential sustainability trade-offs and reduce potential claims of CE-related greenwashing. Practical recommendations are offered for developing targets and indicators for CE as well as identifying and reporting CE-specific risks and opportunities