Delayed Fast Neutron as an Indicator of Burn-Up for Nuclear Fuel Elements

Feasibility study of burn-up analysis and monitoring using delayed fast neutrons was investigated at Missouri University of Science and Technology Reactor (MSTR). Burnt and fresh fuel elements were used to collect delayed fast neutron data for different power levels. Total reactivity varied depending on the burn-up rate of fuel elements for each core configuration. The regulating rod worth was 2.07E-04 Δk/k/in and 1.95E-04 Δk/k/in for T121 and T122 core configurations at 11 inch, respectively. Delayed fast neutron spectrum of F1 (burnt) and F16 (fresh) fuel elements were analyzed further, and a strong correlation was observed between delayed fast neutron emission and burn-up. According to the analyzed peaks in burnt and fresh fuels, reactor power dependency was observed and it was determined that delayed neutron provided more reliable results at reactor powers of 50 kW and above

Proactive strategies in personal dose monitoring, prevention and mitigation

At certain threshold, nuclear radiation (like x-rays and gamma-rays) may adversely impact the health of living tissues. The exposure to these radiations in nuclear facilities is measured by devices called dosimeters. The devices are generally worn on the torso and are monitored by health physics division to report the radiation dose received by the personnel. However, this approach is not proactive--since the dosimeters reflect the dose that has already been absorbed in the body of the wearer. This work presents a scheme to proactively avoid large dose acquisition at radiation-prone facilities. The work was divided into three major segments: (i) identify and characterize radioactive source(s), (ii) determine the impact of localized source(s), and (iii) estimate the integrated doses in traversing/evacuating the facility. The scope of this work does not extend to the development of proactive dosimeter. However, the approaches developed in these segments will be integrated into a dose monitoring system that would prevent or mitigate large dose acquisition. This work also has applications in nuclear facilities, hospitals, homeland security, and border protection --Abstract, page iv

Improving urban water quality for livelihoods enhancement in the Odaw-Korle river catchment of Accra, Ghana

Water and environmental resources which provide opportunities for households are threatened by human activities that leads to pollution. The research objectives were to understand the contribution water makes to the livelihoods of urban and peri-urban households; the factors influencing perceptions, attitudes and behaviour in relation to surface water and environmental quality, and measures for promoting community participation in water and environmental management. Ten communities were selected in Accra and its surrounding communities to reflect different levels of infrastructure provision for the study. Four focus group discussions were held in each community, with a mixed group, men, women, and young adults. Issues which emerged were investigated further in a structured household questionnaire survey involving 443 respondents. Key informant interviews were held with the most important government and non government regulatory, research and service provision departments and organizations in water, sanitation, and the environment sectors. Water samples from some of the selected communities were analyzed in the laboratory to compare with respondents’ perceptions. Among the households surveyed, 59.14% were engaged in a water dependent occupation which contributed over 80% of household income in some cases. The study also found that perceptions of water and environment are influenced by the existing social and cultural setting. There were common concepts which helped groups to interpret and make meaning from their environment. The prospects for successful water and environmental interventions can be enhanced through an understanding of this local knowledge and perceptions. There was no clear relationship between attitudes and environmental behaviour or between attitudes and socioeconomic status. Actual behaviour was influenced by ability to pay for services, their availability and the influence of shared community norms. Although citizen participation in water and environmental management decision making is very limited at present, community collective action holds good prospects for future interventions in water and environmental management

Effect of rare disaster risks on crude oil : evidence from El Niño from over 145 years of data

We extend the literature on the effect of rare disaster risks on commodities by examining the effect of the El Niño-Southern Oscillation (ENSO) on crude oil via the recently developed kth order nonparametric causality-in-quantile framework, utilizing a long-range historical data set spanning the period 1876:01 to 2021:04. The methodology allows us to test for the predictive role of ENSO over the entire conditional distribution of not only real oil returns but also its volatility, by controlling for misspecification due to uncaptured nonlinearity and regime changes. Empirical findings show that the Southern Oscillation Index (SOI), measuring the ENSO cycle, not only predicts real West Texas Intermediate (WTI) oil returns of the United States (US), but also volatility, over the entirety of the respective conditional distributions. The findings highlight the role of rare disaster risks over not only financial markets, but also commodities with significant implications for policymakers and investors.http://link.springer.com/journal/704hj2023Economic

Design and characterization of a strong positron source at the MSTR beam port

“For many years, slow positron sources have found uses in diverse fields including medical physics, nuclear physics, biology, surface science, exotic atom research and space science. The purpose of this work is to design and optimize a reactor-based positron source at the Missouri University of Science and Technology Reactor (MSTR) beam port and quantify its intensity. Monte Carlo simulations using the MCNP6 code were used to model the positron production and moderation processes at the MSTR beam port. The thermal neutron flux at the beam port was determined experimentally and used in the source definition of the radiation transport simulations. The source comprised a Cd (n,γ) converter with a tungsten foil grid acting as both pair production target and positron moderator. This work provides rigorously calculated moderator efficiency tabulations for tungsten foil moderators over a relevant range of positron energies and incidence angles. To optimize the positron source for MSTR, slow positron extraction yields were simulated over a range of foil thickness, grid lengths, foil-to-foil pitch sizes, and extraction voltages. A 3 cm in length by 0.2 cm in pitch tungsten grid with 10 μm thick foils was found to maximize the rate of positron extraction in an extraction potential range of 100 to 300 V while longer and narrower grids are more efficient at higher extraction potentials. In its current core configuration, the MSTR would provide a comparatively weak source of positrons. However, several methods for increasing positron yield are suggested including: reconfiguring the core, increasing reactor power, and placing the positron source inside the beam tube”--Abstract, page iii

Fusion transmutation of waste: design and analysis of the in-zinerator concept.

Due to increasing concerns over the buildup of long-lived transuranic isotopes in spent nuclear fuel waste, attention has been given in recent years to technologies that can burn up these species. The separation and transmutation of transuranics is part of a solution to decreasing the volume and heat load of nuclear waste significantly to increase the repository capacity. A fusion neutron source can be used for transmutation as an alternative to fast reactor systems. Sandia National Laboratories is investigating the use of a Z-Pinch fusion driver for this application. This report summarizes the initial design and engineering issues of this ''In-Zinerator'' concept. Relatively modest fusion requirements on the order of 20 MW can be used to drive a sub-critical, actinide-bearing, fluid blanket. The fluid fuel eliminates the need for expensive fuel fabrication and allows for continuous refueling and removal of fission products. This reactor has the capability of burning up 1,280 kg of actinides per year while at the same time producing 3,000 MWth. The report discusses the baseline design, engineering issues, modeling results, safety issues, and fuel cycle impact

An examination of the role of education in supporting the rural economy of southern Ghana

[Introduction:] The data used for writing this thesis was gathered mainly from twenty-one small-scale rural industries which fall under six categories Food, Ceramics, Woodwork, Iron Extraction, Textiles and Bricks and Tiles.These industries were located in five administrative regions of Southern Ghana : Greater Accra, Central, Eastern, Volta and Western; and the fieldwork was conducted over the period of June, 1980 to March, 1981. The total distance covered during the fieldwork was approximately 2,300 miles.The aim of this study, is to bring to focus, the role which adopted European education plays in supporting the Ghanaian rural economy, particularly in the creation of certain attitudes of the rural industrial entre-preneurial and working classes.Previous literature surveyed on this area revealed that concern was mainly directed towards large-size urban-oriented industries in the modern sector of the Ghanaian economy. Therefore, such findings could not be used strictly as a basis for this study although some of their themes were drawn upon. Consequently, the thirty-five hypotheses postulated by this study concerning the influence of formal education on the formation of attitudes, self-concept, job satisfaction, educational relevance to rural industries, teacher influence, skill training programmes, modernization and perceptions of rural small-scale workers had to be investigated in their own right.Computer analysis of the collected data suggests that:(i) The adopted European education has created some awareness in certain categories of the elite to venture into, what until recently, has been termed indigenous industries.(ii) Certain categories of attitudes of rural workers have been strongly influenced in their formation by the process of formal schooling.(iii) Certain categories of attitudes of rural workers which,although necessary for industrial development, have not been significantly influenced in their formation by the process of formal education. (iv) Contrary to widespread belief that rural industries employ mainly first-cycle school leavers, significant proportions of second-cycle and tertiary school leavers find employment in this sector.This thesis has been divided into four parts. Part One consists of Chapters One, Two and Three. In Chapter One, frequently recurring terms throughout the thesis have been defined. Literature on the area to be studied was reviewed in Chapter Two and in Chapter Three, the theme, the problem and the hypotheses arising from review of the literature and statement of the problem were formulated.Part Two consists of Chapters Four and Five. In Chapter Four, Ghana's rural small-scale industries were discussed in relation to European or formal education. Chapter Five examines Ghana's rural small-scale industries in a theoretical context.Part Three consists of Chapters Six, Seven and Eight. The methodology adopted in the research was set out in Chapter Six. In Chapters Seven and Eight, the statistical analysis of fieldwork data were presented.Part Four consists of Chapters Nine and Ten. In Chapter Nine, a synopsis of research results was given and in Chapter Ten, conclusions and implications of research results were stated

Neutronic analysis of pebble-bed cores with transuranics

At the brink of nuclear waste repository crises, viable alternatives for the long term radiotoxic wastes are seriously being considered worldwide. Minor actinides serve as one of these targeted wastes. Partitioning and transmutation in fission reactors is one possible incineration option and could potentially serve as a source of nuclear fuel required for sustainability of energy resources. The objective of this research was to evaluate the neutronic performance of the pebble-bed Very High Temperature Reactor (VHTR) configurations with various fuel loadings. The configuration adjustments and design sensitivity studies specifically targeted the achievability of spectral variations. The development of several realistic full-core 3D models and validation of all modeling techniques used was a major part of this research effort. In addition, investigating design sensitivities helped identify the parameters of primary interest. The full-core 3D models representing the prototype and large scale cores were created for use with SCALE 5.0 and SCALE 5.1 code systems. Initially the models required the external calculation of a Dancoff correction factor; however, the recent release of SCALE 5.1 encompassed inherent double heterogeneity modeling capabilities. The full core 3D models with multi-heterogeneity treatments are in agreement with available pebble-bed High Temperature Test Reactor data and were validated through benchmark studies. Analyses of configurations with various fuel loadings have indicated promising performance and safety characteristics. It was found that through small configuration adjustments, the pebble-bed design can be tweaked to produce desirable spectral shifts. The future operation of Generation IV nuclear energy systems would be greatly facilitated by the utilization of minor actinides as a fuel component. This would offer development of new fuel cycles, and support sustainability of a fuel source

Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation: Special Report of the Intergovernmental Panel on Climate Change

This Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) has been jointly coordinated by Working Groups I (WGI) and II (WGII) of the Intergovernmental Panel on Climate Change (IPCC). The report focuses on the relationship between climate change and extreme weather and climate events, the impacts of such events, and the strategies to manage the associated risks. The IPCC was jointly established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), in particular to assess in a comprehensive, objective, and transparent manner all the relevant scientific, technical, and socioeconomic information to contribute in understanding the scientific basis of risk of human-induced climate change, the potential impacts, and the adaptation and mitigation options. Beginning in 1990, the IPCC has produced a series of Assessment Reports, Special Reports, Technical Papers, methodologies, and other key documents which have since become the standard references for policymakers and scientists.This Special Report, in particular, contributes to frame the challenge of dealing with extreme weather and climate events as an issue in decisionmaking under uncertainty, analyzing response in the context of risk management. The report consists of nine chapters, covering risk management; observed and projected changes in extreme weather and climate events; exposure and vulnerability to as well as losses resulting from such events; adaptation options from the local to the international scale; the role of sustainable development in modulating risks; and insights from specific case studies