Session: DA-01-03 Design and Analysis of Pressure Vessels and Components-3

Paper Number: 123110

123110 - Hydrogen Vessel Weld Porosity Stress Analysis Using Ct Scan Data 

The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory produces the most intense, pulsed neutron beams in the world for various scientific research experiments and industrial development activities. The neutrons spalled from a mercury target are moderated and filtered into instrument channels by the Inner Reflector Plug (IRP), which is designed for the purpose of moderating, reflecting, and shielding these neutrons and other particles. The SNS lower IRP is the bottom-most segment of the inner reflector plug components. The lower IRP is a complex structure consisting of an aluminum vessel, beryllium and stainless-steel reflectors, water and cryogenic hydrogen moderators, neutron poisons, and various channels for neutron transport.  The lower IRP must be replaced regularly due to consumption of the neutron poisons and embrittlement of the structural materials from radiation.

The hydrogen moderators are a welded constructed from 6061-T6 aluminum. Each vessel has one piping connection with concentric tubing for supply and return of 18K hydrogen.  Currently, the hydrogen moderator vessel body is welded with the connecting tubes using gas tungsten arc welding (GTAW). Radiographic Testing (RT) scan had indicated porosity within the weld but did not define the location or shape of the porosity. For a better definition of the weld defects, the computed tomography (CT) scan technique was used to produce an accurate 3D image of the weld and weld defects. This paper will describe the procedure to incorporate the CT scan porosity data into the finite element model of a hydrogen moderator with GTAW weldment to determine fitness-for-service. The stress analysis was performed to evaluate the weld defects and to qualify the GTAW weldment via the ASME BPVC design criteria.

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 and the Inner Reflector Plug (IRP) 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 SNS over the years, Hao has also worked on analysis and testing of fuel cladding and spent nuclear fuel assemblies. She has more than 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
Douglas Armitage Oak Ridge National Laboratory
Nick Summerlot Oak Ridge National Laboratory