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Product Quality
Published in G.K. Awari, C.S. Thorat, Vishwjeet Ambade, D.P. Kothari, Additive Manufacturing and 3D Printing Technology, 2021
G.K. Awari, C.S. Thorat, Vishwjeet Ambade, D.P. Kothari
Eddy-current testing (ET) is used to detect surface and subsurface flaws, such as cracks and pits, in conductive materials using electromagnetic induction. It can be sensitive to surface and near surface conditions and material type. Vacuum leak testing can be an effective way to assure the hermetic seal of a volume or containment vessel. Complications of applying this technique to AM fabricated products include the need for a sealing surface or sealing compound with the rough surface of as-deposited AM parts or the post-machining needed to obtain a flat sealing surface. Sintered, porous product, or partially fused powder surfaces could create a virtual leak or hidden pumping volume, reducing the utility of the process.
Ceramics and glasses
Published in Andrea Chen, Randy Hsiao-Yu Lo, Semiconductor Packaging, 2016
Andrea Chen, Randy Hsiao-Yu Lo
As stated in Chapter 1, hermetic packages are needed for high-reliability, high-performance applications such as military and aerospace applications. By definition, a hermetic seal prevents gases and liquids from penetrating the package and adversely affecting the integrated circuit. Also, because the package is made of ceramic or similar materials, the package can withstand higher operating and environmental temperatures than an equivalent plastic package.
Development of a Sodium Fast Reactor Cartridge Loop Testing Capability for the Versatile Test Reactor
Published in Nuclear Science and Engineering, 2022
Mitchell T. Farmer, Matthew Weathered, Darius Lisowski, Nathan Bremer, Dennis Kilsdonk, Tim Stack, Caleb Tomlin, Chris Plucker, Ed Moreno, Ran Kong, Zhengting Quan, Adam Dix, Seungjin Kim, Mamoru Ishii, Mark Anderson, Andrew Napora
A magnetic pump shaft coupler is also being developed as part of this work. Using a magnetic coupler is attractive as it can maintain a hermetic seal for the cartridge coolant by eliminating the need for a pump shaft seal. A magnetic pump coupler was originally used in the BOR-60 ILC test.2 In that case, the coupler was a pancake-type design and was located just below the reactor head with the pump shaft extending downward to the cartridge loop located in the core region. In the SFR cartridge application described herein, the coupler is an annular design and is integrated into the cartridge itself just below the refueling socket (Fig. 3). This approach has been adopted so that the pump shaft can be detached from the unit during refueling operations, opening up the possibility to leave the cartridge in the core as opposed to extracting the entire unit above the top of the core plane so that the fuel handling machine can function. This approach would simplify refueling operations for the VTR. Finally, the pump shaft will eventually need to be decoupled from the cartridge assembly prior to transfer into a hot cell for PIE. The ability to simply withdraw the pump shaft from the coupler (as opposed to cutting it) would further simplify operations.
The DRESDYN project: liquid metal experiments on dynamo action and magnetorotational instability
Published in Geophysical & Astrophysical Fluid Dynamics, 2019
F. Stefani, A. Gailitis, G. Gerbeth, A. Giesecke, Th. Gundrum, G. Rüdiger, M. Seilmayer, T. Vogt
The construction of the liquid-sodium MRI/TI experiment (figure 6) relies on our experience with HMRI and AMRI gained at the PROMISE facility, and with the TI experiment. One of the main constructional challenges of the new device is to combine a sophisticated mechanical configuration of split end-rings (which is necessary for the MRI part) with appropriate electrical contacts for applying the internal currents that are needed for the TI. As shown by Rüdiger et al. (2003), MRI for liquid sodium starts at a magnetic Reynolds number of Rm=21 and a Lundquist number of Lu=4.4 (both values correspond to the more conservative estimate for different electrical boundary conditions). With a height of the active Tayler–Couette cell of 2 m (figure 2(b)), and an outer radius of 0.4 m, we plan to reach a rotation rate of the inner cylinder of 20 Hz and an axial field of 130 mT, which is in either case more than double the critical value. With view on the safety issues when dealing with one ton of liquid sodium, one of the most critical aspects is the driving of the inner cylinder. For that purpose, a sophisticated magnetic coupler (figure 6(c)) has been developed and already tested, which ensures a hermetic seal of the entire experiment. Another critical part of the experiment is the large coil for generating the axial magnetic field. Great effort was spent to make this field as homogeneous as possible. The resulting construction weighs 5 tons, and will require around 120 kW of electrical power.
Surface Characterization of Depleted Uranium–Molybdenum to Determine Surface Coating Compatibility
Published in Nuclear Technology, 2018
Terry A. Ring, Byung Sang Choi, J. Paulo Perez, Brian Van Devener, Randy C. Polson, Douglas Crawford, Dennis Keiser, Daniel Wachs
Low-enriched uranium (LEU) molybdenum alloys with various atomic percent amounts of molybdenum are being considered as the new fuel for research reactors across Europe and the United States as part of the implementation of a reduced enrichment nuclear safeguard. The LEU for this purpose consists of an 8 to 10 at. % mixture of molybdenum with uranium containing 19.75% 235U and 80.25% 238U. Two U-Mo fuel concepts are being developed: One is a monolithic foil of U-Mo with Al cladding, and the other is a dispersion fuel where U-Mo particles are dispersed into Al powder that is then pressed into a compact foil. This alloy has a unique high-temperature crystal structure that accommodates fission products allowing up to 80% burnup.1 This fuel, in the form of either a powder or a foil, is to be sandwiched between two aluminum plates to form a composite fuel plate that will become part of the reactor core. It is desirable to put a coating on the U-Mo surface to hermetically seal the U-Mo to theoretically deter interdiffusion and still allow for strong attachment to the aluminum matrix and cladding. A good bond between U-Mo and the Al matrix/cladding prevents surface voids where fission gas can concentrate forming blisters at these points at this interface. Blisters will lead to poor heat transfer and undesirable hot spots in the fuel element. Interdiffusion leads to the development of a poor thermal conducting interaction layer of uranium and aluminum. A coating of ZrN is being contemplated for the hermetic seal material for the U-Mo and a good bond between U-Mo and Al matrix/cladding.