Abstract: Condition assessment of spent nuclear fuel prior to permanent storage is an important component of their life cycle assessment. Given their radioactive nature, only external inspection is possible for these systems while damage and conditions of interest are unobserved. The anatomy of containment structures for spent nuclear fuel is quite complex, consisting of a hierarchy of subsystems interconnected at a finite number of joints, thus greatly filtering wave motion and restricting the flow of information throughout this system. In this talk I will describe our effort at prognosis for these systems. Specifically, we develop a highly detailed 200M DOF finite element model. Nested dynamic reduction techniques are used to facilitate the numerical evaluation of this model. Even with such level of detail, modeling errors are still unavoidable and are represented through a combination of non-parametric models (random matrix models for stiffnesses) and parametric models (random variables for joints and fasteners). A six hundred dimensional polynomial chaos expansion (PCE), that also captures non-parametric effects is constructed using projection-pursuit basis adaptation methods. Statistical updating is then implemented to assimilate experimental dynamical measurements made on the external casing with the aim of inferring the nature and location of damage inside the containment structure. The talk will detail the nested structural dynamics construction, the adapted PCE representation, and the specialized updating techniques.
Speaker Bio: Prof. Roger Ghanem holds the Tryon Chair of Stochastic Methods and Simulation at the University of Southern California where he is also Professor in the Departments of Civil & Environmental Engineering and Aerospace & Mechanical Engineering. Prior to joining USC in 2005, he had served on the faculty of Johns Hopkins University and SUNY-Buffalo. Dr. Ghanem's research is in the areas of stochastic analysis and computational science. For the past thirty years, he has worked on scientific, mathematical and algorithmic aspects of uncertainty quantification with applications from across science and engineering. His recent work addresses challenges presented by modeling errors and complex interacting systems such as those exhibiting multiscale and multiphysics behaviors. Dr. Ghanem has co-authored over 200 journal articles related to stochastic systems and predictive science. He has supervised the research of over 20 postdoctoral associates and 40 PhD students.
Dr. Ghanem has served as President of EMI, on the Executive Council of USACM, as Chair of the SIAM-SIAG on Uncertainty Quantification, and on USNCTAM. He is a fellow of AAAS, SIAM, USACM, IACM, and EMI. Dr. Ghanem is the recipient of a number of awards acknowledging his research and teaching contributions. His research has been supported by NSF, ONR, AFOSR, DARPA, DOE, and a number of industries including GM, GE, Daikin, Taisei, Takenaka, and Shimizu.
