Abstract
Liquid metal fast reactors often utilize a tightly packed triangular fuel pins lattice, wrapped with a helical wire spacer, and are enclosed within hexagonally shaped ducts. During reactor operation, a total or partial blockage of subchannel coolant flow may occur within the fuel assembly. This can be due to isolated or combined causes, such as debris collection and accumulation, and cladding deformation. The complexity of flow behavior, phenomena of flow and heat transfer throughout a wire-wrapped fuel assembly, and particularly the effects of channel blockage, has attracted the worldwide research community to pursue extensive experimental and numerical investigations. The 61-pin wire-wrapped experimental bundle at Texas A&M University, with a fully accessible clear test section, has been designed, constructed, and operated to conduct high-resolution measurements of the flow characteristics throughout the bundle. High spatial and temporal resolution measurements of velocity fields along several vertical and horizontal planes throughout the bundle have been produced using advanced laser-based techniques. This article will focus on high-resolution velocity measurements in the interior sub-channels of the 61-pin wire-wrapped fuel assembly featuring a combined approach of matching-index-of-refraction (MIR) and time-resolved particle image velocimetry (TR-PIV) techniques. From the obtained TR-PIV velocity fields, flow statistics such as mean velocity, root-mean-square fluctuating velocity, and Reynolds stress are computed and presented. Spectral analysis is performed on the fluctuating velocity to extract the vortex shedding frequency in the region downstream of the blockage. The experimental results provide a better understanding of the flow behavior under a channel blockage, providing a unique set of experimental data to support the validation of advanced numerical simulation codes.
| Original language | English |
|---|---|
| Pages | 4532-4541 |
| Number of pages | 10 |
| State | Published - 2019 |
| Externally published | Yes |
| Event | 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019 - Portland, United States Duration: Aug 18 2019 → Aug 23 2019 |
Conference
| Conference | 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019 |
|---|---|
| Country/Territory | United States |
| City | Portland |
| Period | 08/18/19 → 08/23/19 |
Funding
Texas A&M University has conducted isothermal flow experiments within of a wire-wrapped 61-pin hexagonal fuel bundle to support the research on advanced nuclear reactors, within the framework of sponsored US Department of Energy (DOE) projects. The experimental facility has been constructed to allow the application of advanced laser-based flow measurement techniques, such as time-resolved particle image velocimetry (TR-PIV) and stereoscopic PIV (TR-SPIV), combined with the matched-index-of-refraction (MIR). The results of these experimental activities will be a high-fidelity experimental database of flow field measurements that will be suitable for validating CFD codes [8]. Nguyen et al. [5], Goth et al. [6], Nguyen et al. [7], and Brockmeyer et al. [9] have shown through previous studies that the flow characteristics within the wire-wrapped fuel assembly are very complicated and strongly influence the flow and heat transfer phenomena between the coolant and fuel rods. The characterization and understanding of channel blockage flow mixing effects are of particularly of interest inside of the interior subchannels of the wire wrapped fuel bundle. This work was performed for the Department of Energy under contract DE-NE000832, and with the intense collaboration of Jadyn Reis and Blaze Boyed, undergraduate students at the Nuclear Engineering Department.
| Funders | Funder number |
|---|---|
| US Department of Energy | |
| U.S. Department of Energy | DE-NE000832 |
Keywords
- Flow Blockage
- PIV
- Wire-Wrapped Assembly