Design of an experimental facility with a unit cell test section for studies of the lower plenum in prismatic high temperature gas reactors

Journal Article · Thu May 23 00:00:00 EDT 2019 · Annals of Nuclear Energy

DOI:https://doi.org/10.1016/j.anucene.2019.05.037· OSTI ID:1848134

Landfried, D. Tyler ^[1]; Kristo, Paul ^[2]; Clifford, Corey E. ^[3]; Kimber, Mark ^[4]

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1. Univ. of Pittsburgh, PA (United States). Dept. of Mechanical Engineering and Materials Science
2. Texas A & M Univ., College Station, TX (United States). Dept. of Mechanical Engineering
3. Texas A & M Univ., College Station, TX (United States). Dept. of Nuclear Engineering
4. Texas A & M Univ., College Station, TX (United States). Dept. of Mechanical Engineering; Texas A & M Univ., College Station, TX (United States). Dept. of Nuclear Engineering

A proposed design for a Generation IV reactor is the very-high temperature reactor (VHTR), which employs helium as the primary coolant. Although many advantages exist with this design, a number of challenges remain. One such area of concern is the turbulent mixing of non-isothermal flows in the lower plenum, where an array of coolant jets collectively mix and traverse around a series of structural support posts before exiting the core. Neighboring jets in the lower plenum could experience temperature differences as high as 300–400 K, causing potential hot streaking in the support posts. Additional problems could occur further downstream if the level of non-uniformity in the temperatures is too high (e.g, inducing thermal stresses on gas turbine blades). Therefore, it is important that adequate tools exist to predict the turbulent mixing within the VHTR lower plenum. This task remains difficult to achieve due to the complex geometry and flow physics that dictate the mixing. Various modeling approaches can only be assessed using data acquired from a carefully designed experimental facility. This paper presents details of such a facility, where high-fidelity measurements can be acquired for a scaled portion of the lower plenum defined herein as a ‘‘unit cell”, which consists of a hexagonal array of jets whose flow is directed into a test section with support posts positioned between neighboring jets, and subjected to a crossflow. Through adjusting velocity and temperature conditions at the jet inlets, different locations within the lower plenum can be experimentally simulated. System response quantities (SRQs) include both temperature and velocity measurements, captured via multiple thermocouples embedded in each post, and particle image velocimetry (PIV), respectively. These SRQs provide assessment metrics for both the momentum and energy models present in current computational solvers, and therefore the experimental facility is a valuable source for validation data. Another benefit is a more comprehensive understanding of the thermal-hydraulic loading conditions and flow physics present in the VHTR lower plenum.

• Research Organization: Univ. of Houston, TX (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE)
• Grant/Contract Number: NE0000718
• OSTI ID: 1848134
• Alternate ID(s): OSTI ID: 1692237
• Journal Information: Annals of Nuclear Energy, Vol. 133, Issue C; ISSN 0306-4549
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Nuclear Science & Technology
Unit cell
Very high temperature reactor
Impinging jets
Bank of cylinders
Thermal striping
Lower plenum