Design of a Unit Cell Facility for Studies of the Prismatic VHTR Lower Plenum Conference Paper uri icon


  • One proposed design for a Generation IV reactor is the very high temperature gas reactor, which uses helium as the primary coolant due to its advantageous properties as an inert gas. One area of concern for the VHTR is the lower plenum, where temperature differences as high as 300-400 K can cause hot streaking. The lower plenum consists of a series of structural posts and an array of coolant jets which lead to a singular outlet from the reactor core. The objective of this study is to present the design for an experimental facility where insight can be gained into flow physics within the VHTR lower plenum. To study the lower plenum mixing behavior, an experimental setup including a test section herein called the 'unit cell' is designed. The unit cell consists of six hexagonally arranged jets directing their flow into the test section and subsequently traveling through a hexagonal array of seven support posts, all in the presence of a cross flow. Temperature profiles are captured via multiple thermocouples embedded in each post. With the 6 jets whose outlets are on the top face of the test section, along with the cross flow at the inlet of the test section, the unit cell is capable of experimentally simulating notable post and jet configurations found in the lower plenum. With the radial temperature profiles, the thermal fluctuations and flow behavior on these posts can be studied. The present work focuses on the scaling and design of the unit cell facility. This facility will be used to provide high quality experimental data for future validation studies as well aid to achieve more comprehensive understanding of the loading conditions which cause the thermal stresses experienced by the structural support posts in the lower plenum of the VHTR.

published proceedings

  • International Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015

author list (cited authors)

  • Landfried, D. T., Kristo, P., & Kimber, M.

complete list of authors

  • Landfried, DT||Kristo, P||Kimber, M

publication date

  • January 2015