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In-Process Inspection System Using Tool-Touch Auditron
Published in Stephan D. Murphy, In-Process Measurement and Control, 2020
The sensor was evaluated in its ruggedized form using the printed circuit board design, as opposed to the earlier hand-wired versions. The acoustic emission transducer was a Dune-gan/Endevco D750. The specified compressional wave frequency bandwidth for this transducer is 100 to 300 kHz with a sensitivity of 60 db at its resonant peak frequency. The same transducer had been used in earlier feasibility testing at GE with the Gray VTL and other machines for both touch sensing and closed-loop machining. The amplifier was the same one used in earlier designs. The unit consists primarily of an active high-pass filter with thresholding and analog-to-digital conversion to provide an appropriate signal for the CNC controller. The updated printed circuit board version of the sensor made provisions for wire wrap selectable filtering. The filter’s high-pass cutoff frequency can be changed via a pad of two resistors and two capacitors. The amplifier gain is easily changed via a pad of four resistors. The amplifier accommodates both single-ended and differential acoustic emission sensors through wire wrap jumpers. The D750 transducer utilized provides a differential signal; thus the amplifier was configured accordingly for the evaluation.
Interconnection technology
Published in Stephen Sangwine, Electronic Components and Technology, 2018
Interconnection technology is of fundamental importance in the design and manufacture of electronic products. Electrical joints in electronic systems are most often made by soldering, although for some purposes wire-wrapping or crimping is used. Soldered joints were made in the past with a low-melting-point tin–lead alloy that dissolves into the surfaces of the metals being joined. From 2006 onwards, tin–lead solder has been replaced in most applications by lead-free solders to avoid the use of lead, which is toxic. Cleanliness, flux, and sufficient heat are essential requirements for a good soldered joint. Different solders are available for different applications: the type of solder to be used should be selected with care. Wire-wrap jointing is an alternative to soldering for some applications and has advantages in ease of alteration for prototype work. The integrity of a wire-wrap joint depends on good metal-to-metal contact brought about by the pressure of the wire on the sharp corners of the terminal pin.
Fast Reactors, Gas Reactors, and Military Reactors
Published in Robert E. Masterson, Nuclear Engineering Fundamentals, 2017
The fuel rods in LMFBRs are stainless steel tubes about 7–8 mm in diameter, and the average diameter of a fuel pin is about 6.6 mm. The fuel pellets inside of the pins contain a mixture of uranium and plutonium dioxide (UO2 and PuO2), and the amount of plutonium in the fuel pins is equal to between 15% and 35% of the total uranium content (by weight). The fuel pins are much closer together than they are in a water reactor (about 17%), and they are kept apart by spacers, or in some cases, helically wound wire around each fuel pin. The helically wound wire is sometimes called a wire-wrap. Using a helical wire in a fuel assembly has the advantage that it increases the amount of turbulent mixing, and therefore, it helps to increase the heat transfer rate between the fuel rods and the coolant. It can also provide additional structural stability and integrity in some cases. The fuel rods in the radial blanket are generally much larger than they are in the core. These rods contain UO2, and almost all of the uranium in the blanket is U-238. The average diameter of a fuel pin in the blanket is about 15 mm. This is about twice as large as a typical fuel pin in the core. The layout of the fuel pins in the core and blanket regions is shown in Figure 15.6. Notice that the diameter of the fuel rods in the axial blanket (above and below the core) is the same as that in the core, but in the radial blanket, the rods are much larger. The larger diameters can be tolerated because they require less cooling than the fuel pins in the core do.
Subchannel Analysis of LFR Wire-Wrapped Fuel Bundle with RELAP5-3D
Published in Nuclear Technology, 2023
Cristiano Ciurluini, Vincenzo Narcisi, Ivan Di Piazza, Fabio Giannetti
The rationale behind the FPS modeling follows the lessons learned from Refs. [14] and [21]. The presence of wires wrapped to the pins leads to an increase in bundle pressure drop and enhances the cross flow among adjacent channels by adding a swirl contribution. Indeed, when the axial flow meets the wire wrap, it starts to swirl around the pin following the wire-wrap helical shape. These two phenomena must be properly simulated while developing the RELAP5-3D model. To do it, several aspects must be carefully considered: (1) the FPS geometrical scheme; (2) the cross-flow model, to account for the lateral mass exchange between subchannels; (3) the wire-wrap induced turbulent mixing model, generating mass and energy transfer among adjacent channels; (4) the fluid conduction model, in both axial and radial directions. To separately evaluate their impact on the simulation outcomes, three different FPS models were tested against experimental results. The first contains the improved geometrical scheme for the FPS and the cross-flow model only (‘cfmo’). In the second, the wire turbulent mixing (‘wtm’) was added. Finally, also, the fluid thermal conduction (‘ftc’) was included in the input deck.
Turbulent Mixing Models and Other Mixing Coefficients in Subchannel Codes—A Review Part A: Single Phase
Published in Nuclear Technology, 2020
Aiguo Liu, Bao-Wen Yang, Bin Han, Xianlin Zhu
For fuel bundles, two kinds of spacers are widely used, i.e., wire wrap and spacer grid. As flow runs into spacers, directional disturbance is generated that redistributes the flow field downstream. The turbulence and velocity field change dramatically with strong inter-subchannel cross flow and turbulent mixing. The first subchannel code that reflected the spacers’ influence was COBRA-IIIC with the wire wrap model.50 The DRM for wire wrap has been embedded in the COBRA-IIIC, original COBRA-IV, and other Liquid Metal Fast Breed Reactor subchannel analysis codes. In these models, the transverse mass flow rate due to the wire-forced flow component was given as directly proportional to the subchannel mass flow rate multiplied by π(D+Dw)/H where D and Dw are the fuel pin and wire spacer diameters and H is the wire lead length. Apparently the forced cross-flow models are based solely on continuity considerations and do not account for momentum effects. Hence, Ninokata et al.51 modified the DRM model to account for the momentum effect by adding drag force components into the momentum conservation equations. The distributed resistance forces experienced by the solid walls (rod and wire spacer) due to fluid motion are shown in Fig. 22. The drag force components are the function of Re, wire wrap angle, etc. The flow condition was also extended to the laminar flow.
Coupled Monte Carlo Transport and Conjugate Heat Transfer for Wire-Wrapped Bundles Within the MOOSE Framework
Published in Nuclear Science and Engineering, 2023
A. J. Novak, P. Shriwise, P. K. Romano, R. Rahaman, E. Merzari, D. Gaston
This concludes the application of Cardinal to a seven-pin version of the ABR driver assembly. The seven-pin ABR simulations were conducted on Summit and required approximately 60 node hours for the isothermal flow solve and an additional 100 node hours for the coupled physics energy solve (on a frozen velocity field). Cardinal predicts realistic temperature and power distributions for SFR geometries, but additional validation is required for the wire-wrap MSM. Comparisons of Cardinal CHT simulations using the wire-wrap MSM using a 61-pin partially heated wire-wrap experiment33 are underway. Pending acceptable accuracy, the MSM will provide a pathway toward full-core RANS modeling of SFRs.