Robert J. Pink

Idaho National Laboratory Experimental Program to Measure the Flow Phenomena in a Scaled Model of a Prismatic Gas-Cooled Reactor Lower Plenum for Validation of CFD Codes

The experimental program that is being conducted at the Matched Index-of-Refraction (MIR) Flow Facility at Idaho National Laboratory (INL) to obtain benchmark data on measurements of flow phenomena in a scaled model of a prismatic gas-cooled reactor lower plenum using 3-D Particle Image Velocimetry (PIV) is presented. A description of the scaling analysis, experimental facility, 3-D PIV system, measurement uncertainties and analysis, experimental procedures and samples of the data sets that have been obtained are included. Samples of the data set that will be presented include the mean velocity field in an approximately 1:7 scale model of a region of the lower plenum of a typical prismatic gas-cooled reactor (GCR) similar to a General Atomics Gas-Turbine-Modular Helium Reactor (GTMHR) design. This experiment has been selected as the first Standard Problem endorsed by the Generation IV International Forum. The flow in the lower plenum consists of multiple jets injected into a confined cross flow — with obstructions. The model consists of a row of full circular posts along its centerline with half-posts on the two parallel walls to approximate flow scaled to that expected from the staggered parallel rows of posts in the reactor design. The model is fabricated from clear, fused quartz to match the refractive-index of the mineral oil working fluid. The benefit of the MIR technique is that it permits high-quality measurements to be obtained without locating intrusive transducers that disturb the flow field and without distortion of the optical paths. An advantage of the INL MIR system is its large size which allows obtaining improved spatial and temporal resolution compared to similar facilities at smaller scales. Results concentrate on the region of the lower plenum near its far reflector wall (away from the outlet duct). Inlet jet Reynolds numbers (based on the jet diameter and the time-mean average flow rate) are approximately 4,300 and 12,400. The measurements reveal developing, non-uniform flow in the inlet jets and complicated flow patterns in the model lower plenum. Data include three-dimensional vector plots, data displays along the coordinate planes (slices) and charts that describe the component flows at specific regions in the model. Information on inlet velocity profiles is also presented.© 2008 ASME

Hot Hydrogen Test Facility

The core in a nuclear thermal rocket will operate at high temperatures and in hydrogen. One of the important parameters in evaluating the performance of a nuclear thermal rocket is specific impulse, ISp. This quantity is proportional to the square root of the propellant’s absolute temperature and inversely proportional to square root of its molecular weight. Therefore, high temperature hydrogen is a favored propellant of nuclear thermal rocket designers. Previous work has shown that one of the life-limiting phenomena for thermal rocket nuclear cores is mass loss of fuel to flowing hydrogen at high temperatures. The hot hydrogen test facility located at the Idaho National Lab (INL) is designed to test suitability of different core materials in 2500°C hydrogen flowing at 1500 liters per minute. The facility is intended to test non-uranium containing materials and therefore is particularly suited for testing potential cladding and coating materials. In this first installment the facility is described. Automated Data acquisition, flow and temperature control, vessel compatibility with various core geometries and overall capabilities are discussed.

Physical and Computational Modeling for Chemical and Biological Weapons Airflow Applications

There is a need for information on dispersion and infiltration of chemical and biological agents in complex building environments. A recent collaborative study conducted at the Idaho National Engineering and Environmental Laboratory (INEEL) and Bechtel Corporation Research and Development had the objective of assessing computational fluid dynamics (CFD) models for simulation of flow around complicated buildings through a comparison of experimental and numerical results. The test facility used in the experiments was INEEL’s unique large Matched-Index-of-Refraction (MIR) flow system. The CFD code used for modeling was Fluent, a widely available commercial flow simulation package. For the experiment, a building plan was selected to approximately represent an existing facility. It was found that predicted velocity profiles from above the building and in front of the building were in good agreement with the measurements.

Measurements and Code Comparisons for Advanced Gas Reactor Coolant Channels Containing Spacer Ribs

Core coolant channels and control rod passages in prismatic gas-cooled nuclear reactors consist of typically hexagonal arrays of circular tubes or annuli containing spacer ribs. A major goal of an ongoing study to characterize the fundamental thermal fluid physics of high temperature flows in gas cooled reactors is to guide code development and assess code capabilities for treating forced convection problems in advanced reactors. Flow through an idealized annular channel containing an array of spacer ribs is examined both experimentally and computationally without complicating thermal phenomena. Laser Dopler Velocimetry (LDV) measurements in a transparent quartz model with index-matching oil flow are obtained in the INEEL’s unique large Matched Index of Refraction (MIR) flow facility to determine the velocity and turbulence fields, and to provide visualization of the flow. Experimental results are compared with numerical computations as a first step to understanding heat transfer enhancement and hindrance by the bluff spacer rib bodies.Copyright