Evaluation, Construction, and Verification of a Subchannel Steady State Heat Transfer Code for Plate-Fueled Reactors

Several high performance research reactors use plate fuel that is clad with aluminum and cooled with forced convection of subcooled water. High resolution multiphysics simulation tools have been developed to allow the performance of the core in these reactors to be assessed in more detail. The high resolution multiphysics (HRMP) simulation tools must go through verification and validation (V&V) to ensure the additional detail of the outcomes is accompanied with quantifiable uncertainties and confidence intervals. As an example of V&V, a one-dimensional subchannel code with conventional engineering flow and heat transfer models may be used to check the performance of a three-dimensional computational fluid dynamics assessment. This work develops a plate-fueled reactor subchannel steady state heat transfer code (PFSC) using a one-dimensional subchannel model. V&V is done for the PFSC by deriving several key equations, which are used in the subchannel heat transfer analysis, from the Reynolds Transport Theorem. This activity allows the subchannel model to be extended to include uncertainties and biases associated with the modeling simplifications, which can extend the utility of the subchannel model as a tool for testing the HRMP model. The initial basis for the development of the subchannel code is the High Flux Isotope Reactor (HFIR), which is a leading example of a high performance plate-fueled research reactor. The PFSC includes new features from the existing HFIR Steady State Heat Transfer Code (SSHTC) such as density and elevation changes in the momentum and energy equations, friction losses and internal heat generation in the energy equation, more accurate correlations for the thermophysical properties of water, new models used as limiting criteria in the reactor analysis, and flags that separate the heat transfer and fluid flow from fuel plate surface oxidation and deflections. A code to code comparison is done between the new flexible subchannel code and the HFIR SSHTC, as well as a comparison to an analytical solution for a simplified case with uniform heat flux and constant fluid properties. Biases associated with the one-dimensional assessment of the subchannel model are also reviewed. These activities provide quality assurance for the PFSC

Gaps in College Biology Students\u27 Understanding of Photosynthesis: Implications for Human Constructivist Learning Theory and College Classroom Practice.

The main research question of this study was: What gaps in biochemical understanding are revealed by a range of university introductory biology students as they work through a critically acclaimed multimedia program on photosynthesis, and what are the corresponding implications for elaboration of the Ausubel-Novak-Gowin Learning Theory (ANG, now Human Constructivism)? Twelve students, mixed for ability, gender and ethnicity, were recruited from two sections of Bio 101. Before and after instruction in photosynthesis, in-depth clinical interviews were conducted during which participants completed a range of cognitive tasks such as sorting, concept mapping, explaining and predicting. Some tasks involved interacting with a computer simulation of photosynthesis. This study primarily employed qualitative case study and verbal analysis methods. Verbal analysis of the clinical interviews revealed numerous gaps that were categorized into typologies. The two major categories were propositional gaps and processing gaps. Propositional gaps were evident in development of participants\u27 concepts, links and constructs. Significant among these were conceptual distance gaps and continuity of matter gaps. Gaps such as convention gaps and relative significance gaps seem to be due to naivete in the discipline. Processing gaps included gaps in graphic decoding skills and relevant cognitive habits such as self-monitoring and consulting prior knowledge. Although the gaps were easier to detect and isolate with the above-average participants, all participants showed evidence of at least some of these gaps. Since some gaps are not unexpected at all but the highest literacy levels, not all the gaps identified are to be considered deficiencies. The gaps identified support the attention given by ANG theorists to the role of prior knowledge and metacognition as well as the value of graphic organizers in knowledge construction. In addition, this study revealed numerous gaps in graphic decoding, indicating that both direct experience and explicit instruction are needed if students are to learn how to learn with graphics, especially those graphics central to understanding a computer simulation\u27s representations of structures, inputs, processes and outputs. It is hypothesized that gaps similar to those revealed in this study may be at the root of some alternative conceptions documented in the literature

PRINCIPAL LEADERSHIP AS A MODERATOR OF TEACHER TURNOVER FOLLOWING NATURAL HAZARD EXPOSURE

This study investigated principal leadership as a moderator of teacher turnover following natural hazard exposure. Like other disruptions to schooling, such as pandemics, natural hazard exposure is associated with a variety of negative outcomes in schools, including increased stress for teachers and lowered achievement for students. Using statewide administrative personnel records, I explored whether teacher turnover follows natural hazard exposure. I also explored the extent to which natural hazard exposure is associated with teacher turnover by comparing turnover rates across schools affected by one or more exposures. Using interview data, I also investigated the support and care school principals exhibited toward teachers following a natural hazard exposure. Through a sequential mixed methods design, I aimed to determine the influence principal leadership may have on teacher turnover in schools exposed to a natural hazard through leaders’ crisis management and caring leadership behaviors. The study presents nuanced evidence that can guide school and district leaders and policymakers looking for information about how principal leadership can attenuate teacher turnover in the context of a school exposed to a natural hazard. In addition, the study adds to the emerging literature on the effects of natural hazard exposure on schools, as these effects are a pressing issue due to global climate change and the expected increases in natural hazard exposure.Doctor of Philosoph

Recommendations for​ Wildfire Recovery Planning for the City of Arcata

Western landscapes are experiencing an increased scale and intensity of wildfires, due in part to climate change, fire suppression, and an expanding wildland-urban interface. The damage to human lives and property caused by wildfires has prompted all levels of government to galvanize planning efforts to better respond to and recover from wildfire. This report summarizes the need for effective wildfire recovery planning for the City of Arcata, California. The city is currently working on its Hazard Mitigation Plan to be eligible for funding under FEMA hazard mitigation grant programs. This report seeks to inform the city by highlighting the importance of incorporating recovery planning into the Hazard Mitigation Plan. Research was conducted via review of other plans and interviews of officials and those affected by wildfires. The gathered information was used to identify current short and long-term resources that exist for the recovery of residents, businesses, and schools. Through this process gaps in current wildfire recovery resources were identified and this information was used to make recommendations to the City of Arcata for their Hazard Mitigation Plan. Recommendations include drafting a comprehensive debris removal plan, having a plan to disseminate information to affected persons, and identifying areas where temporary housing could be erected

School-based mental health supports during COVID-19: School professional perspectives

The present study explored the ways school professionals adapted school-based mental health supports and services for remote delivery during the coronavirus disease 2019 (COVID-19) pandemic. We surveyed 81 school professionals (e.g., counselors, psychologists, and social workers) and conducted in-depth interviews with a subsample of professionals (n = 14) to explore their perceptions and experiences of supporting youth with mental health concerns and suicide-related risk during the fall and winter of the 2020–2021 school year. Commonly endorsed school-based mental health interventions (e.g., counseling services and checking in), ways of communicating (phone and email), and individuals delivering support and services to students with suicide-related risk (e.g., counselors and teachers) were identified based on school professional survey responses. Qualitative findings point to facilitators (e.g., specific platforms for connecting with students and families) and barriers (e.g., limited communication) to successful service delivery during COVID-19. Findings highlight the creative ways school support professionals adapted to provide school-based mental health supports. Implications for remote school-based mental health services during and following the pandemic are discussed

Project X: Physics Opportunities

Part 2 of "Project X: Accelerator Reference Design, Physics Opportunities, Broader Impacts". In this Part, we outline the particle-physics program that can be achieved with Project X, a staged superconducting linac for intensity-frontier particle physics. Topics include neutrino physics, kaon physics, muon physics, electric dipole moments, neutron-antineutron oscillations, new light particles, hadron structure, hadron spectroscopy, and lattice-QCD calculations. Part 1 is available as arXiv:1306.5022 [physics.acc-ph] and Part 3 is available as arXiv:1306.5024 [physics.acc-ph]