a b s t r a c tIn severe accident conditions with loss of active cooling in the core, zirconium alloys, used as fuel cladding materials for current light water reactors (LWR), undergo a rapid oxidation by high temperature steam with consequent hydrogen generation. Novel fuel technologies, named accident tolerant fuels (ATF), seek to improve the endurance of severe accident conditions in LWRs by eliminating or at least mitigating such detrimental steam-cladding interaction. Most ATF concepts are expected to work within the design framework of current and future light water reactors, and for that reason they must match or exceed the performance of conventional fuel in normal conditions. This study analyzed the neutronic performance of ATF when employed in both pressurized and boiling water reactors. Two concepts were evaluated: (1) coating the exterior of zirconium-alloy cladding with thin ceramics to limit the zirconium available for reaction with high-temperature steam; (2) replacing zirconium alloys with alternative materials possessing slower oxidation kinetics and reduced hydrogen production. Findings show that ceramic coatings should remain 10e30 mm thick to limit the neutronic penalty. Alternative cladding materials, with the exception of SiC, enhance neutron loss compared to zirconium-alloys. An extensive parametric analysis concluded that reference performance metrics can be met by employing 300-mm or less thick cladding or increasing fuel enrichment by up to 1.74% depending on material and geometry.
This paper presents an investigation of the application of a suite of sensors for simultaneous in-situ measurements of machining processes. While not every individual sensor responds to all machining phenomena, the suite of sensors together responds to many machining phenomena of interest, including chip segmentation, chip breakage, and vibrations. The simultaneous use of a suite of sensors with modest data-acquisition equipment and the use of careful preliminary laboratory testing for optimizing sensor performance distinguishes this present proof-of-concept work from prior process monitoring efforts using individual sensors. This paper includes a discussion of pre-deployment laboratory measurements and a full description of the instrumented tool holder, associated circuitry, and data analysis methods. The deployment of multiple sensors of varying sophistication and cost lays a technical foundation for the ultimate objective of industrially practical measurement and monitoring systems for metal cutting processes.
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