The ORNL’s Spallation Neutron Source (SNS) is a megawatt class accelerator-based pulsed neutron source. In this facility neutrons are produced via high-energy spallation reactions induced by colliding 1 GeV protons into liquid mercury at a frequency of 60 Hz. The spallation process causes a temperature rise in the mercury on the order of 107 K/s. The isochoric energy deposition leads to several complex thermal-hydraulic phenomena in the SNS-target system such as the formation of tensile pressure waves that cavitate the mercury, “micro flow jets” inducing erosion of the vessel walls, increase of localized structural pressure loads, integral vessel fatigue, among others.
Technical Approach
The design and improvement of various generations of target designs have depended heavily on computational tools to forecast and virtually test the performance of SNS targets. In order to quantify the accuracy and validity of the predictions made by Computational Fluid Dynamics (CFD), a series of experiments have been performed utilizing state-of-the-art full field, non-intrusive measurement techniques. A set of full scale transparent test sections have been fabricated and installed to perform Particle Image Velocimetry measurements of the various SNS target designs.
Benefit
Validation and Verification of CFD predictions have been performed with excellent results. Testing of hydraulic performance of various new components in the transparent test section has helped to improve target reliability.
Sponsor
SNS
Principal Investigator
Elvis Dominguez-Ontiveros
