The Polywell fusion concept, originally proposed by Robert W. Bussard in 1985, has been investigated for over four decades as a potential solution for achieving net fusion energy in a compact and economically viable reactor. It combines two distinct approaches: high-beta magnetic cusp confinement of electrons using polyhedral coil configurations and electrostatic ion confinement via a potential well formed by injected electron beams. While the hybrid nature of the Polywell system offers advantages in plasma stability and engineering simplicity, previous efforts have been limited by persistent challenges in achieving sufficient plasma confinement required to generate a net energy gain. In this study, we examine previous works and identify limitations of several Polywell embodiments that have historically impeded progress. We present an updated Polywell physics model incorporating experimental findings and recent first-principles particle-in-cell simulations. This updated model outlines a credible path toward overcoming confinement losses and achieving net energy gain using deuterium-tritium (D-T) fuels. Our findings provide a renewed scientific basis for the continued development of the Polywell fusion concept as a practical and scalable approach to fusion energy.
As standards discussions progress covering hydrogen transmission by pipeline, and new test data become available, it is important there exists a common understanding of the key terms and nomenclature associated with the various forms of hydrogen damage and the mechanisms of hydrogen embrittlement. A glossary of terms and descriptions of typical test methods and nomenclature are provided to enhance communication between individuals involved in discussions of the effects of hydrogen on pipeline steels. Differences will always exist in definitions of terms, particularly between various industries. However, the information provided here tries to provide the broadest possible usage, with particular emphasis on the pipeline community.
This project addresses pragmatic application of the new DOT/PHMSA MegaRule RIN 1 - 192.712 for recommended toughness values for determining if an ILI detected axial flaw needs repair or can instead be observed for any future growth. The MegaRule toughness is expressed as the Charpy energy value, which came from Charpy test data at 50�F. However, the fracture toughness of a surface-cracked pipe is quite different than Charpy impact toughness values, especially if the Charpy data is in the brittle-to-ductile transition region. The surface-cracked pipe burst-pressure transition temperature can be greatly lower than the Charpy impact specimen transition temperature due to loading rates and constraint effects (bending versus tension loading). In cases with axial surface cracks in vintage base-metal pipe tests, the surface-cracked pipe burst pressure transition temperature was greater than 200�F lower than the Charpy transition temperature. The procedures were extended to welds, and in the Level 1 report, databases from member companies were examined to establish what Charpy energy values should be used to reflect the toughness of a surface crack in the pipe at the operating temperatures, and still be consistent with the MegaRule Charpy information and safety desires.
This project details the methodologies used to collect and review crack failures, near misses and false positives, and how the available technologies are used in consideration of the CM-SRP pillars of crack (1) susceptibility, (2) inspection, (3) assessment and remediation, and (4) management. This project outcome enhances crack management by providing an independent review and understanding of the research gaps as they relate to cracking in pipelines, based on historic incidents, operator interviews, and subject matter expert opinions. The scope of work consisted of developing future research guideline suggestions through the following tasks: * Task 1 - Collection and review of publicly available reports, * Task 2 - Collection and review of PRCI member incident reports and operator interviews, * Task 3 - Compilation of root causes for historic crack-related pipeline incidents, * Task 4 - Categorization of root causes within the CM-SRP, and * Task 5 - Identification of research gaps in the CM-SRP. This report provides more details about the research suggestions, and cross-references them with the core priorities as outlined in CM-SRP report "Pathway to Achieving Efficient and Effective Crack Management," as well as the future research project ideas that have been submitted to PRCI four CM-SRP pillars. This report has a related Webinar.
Abstract This article provides an outline of the issues to consider in performing a probabilistic life assessment. It begins with an historical background and introduces the most common methods. The article then describes those methods covering subjects such as the required random variable definitions, how uncertainty is quantified, and input for the associated random variables, as well as the characterization of the response uncertainty. Next, it focuses on specific and generic uncertainty propagation techniques: first- and second-order reliability methods, the response surface method, and the most frequently used simulation methods, standard Monte Carlo sampling, Latin hypercube sampling, and discrete probability distribution sampling. Further, the article discusses methods developed to analyze the results of probabilistic methods and covers the use of epistemic and aleatory sampling as well as several statistical techniques. Finally, it illustrates some of the techniques with application problems for which probabilistic analysis is an essential element.
