Session: DA-09-01 Piping and Equipment Dynamics and Dynamic Response Analysis

Paper Number: 106307

106307 - Repeatability and Uncertainty Study of Dynamic Strain Data Measured on the Coupled Fluid-Structure Vessels in Response to High Intensity Proton Pulses 

Spallation Neutron Source (SNS) produces neutrons through spallation reactions with the short pulse (~0.7 µs) operated at a repetition rate of 60 Hz with 1.0 GeV protons onto the mercury target in a stainless-steel vessel. Considering the short pulse length and relatively large incident beam dimensions of 200 mm by 70 mm, the heating from a pulse is essentially isochoric. Therefore, each pulse causes a distributed pressure field in the mercury, with pressures exceeding 20 MPa. Dynamic high-pressure waves created by the proton pulses interact with the stainless-steel vessel. Fluid-structure interaction causes stress cycles in the target vessel and leads to fatigue cracks and cavitation of the mercury, which leads to further damage. Strain measurements are critical for understanding and improving the lifetime of the target vessels. The measurements also allow evaluation of the efficacy of pulse mitigation techniques such as injecting small helium gas bubbles into the flowing mercury.

 

Since 2015, researchers at SNS have used fiber-optic sensor systems to measure dynamic strain responses of the target vessels. These systems have been improved significantly over the years. An abundance of detailed mercury target strain data has been collected and is available for evaluation. We would like to use these strain data to validate simulation results. It is important that the uncertainty of the measurements is quantified as part of the validation process. This paper focuses on the repeatability and uncertainty study in strain measurement data of SNS target vessels. The approach used for data analysis is described and the potential reasons causing the variance associated with measurements are further investigated and discussed. 

Presenting Author: Hao Jiang Oak Ridge National Lab

Presenting Author Biography: Hao Jiang is currently working as a R&D Mechanical Engineer in Spallation Neutron Source, Oak Ridge National Lab. She supports reliable operation and improvements to the target systems through development and analysis activities focused on the mechanical responses of components to loads. Hao earned her Bachelor's and Master's degrees from Tongji University, and her Ph.D. in Mechanical Engineering from Purdue University. In addition to her support of target systems over the years, Hao has also worked on analysis and testing of fuel cladding and spent nuclear fuel assemblies. She has 20 years’ experience in mechanical system analysis and evaluation and has author and co-author numerous journal and conference papers.

Authors:

Hao Jiang Oak Ridge National Lab
Drew Winder Oak Ridge National Laboratory
Yun Liu Oak Ridge National Laboratory