Nathan O. Siu received his Ph.D. in Nuclear Science and Engineering from the University of California, Los Angeles. His general area of expertise is in the development of advanced methods for probabilistic risk assessment. Specific areas include the risk of dynamic accident sequences, the influence of plant operators on accident evolution, the potential effect and significance of internal fires, and the treatment of uncertainties.

Dr. Siu is currently serving as a Senior Technical Adviser in Probabilistic Risk Assessment (PRA) for the Probabilistic Risk Analysis Branch of the Office of Nuclear Regulatory Research for the U.S. Nuclear Regulatory Commission (NRC). He is responsible for advising management on PRA issues, for developing PRA research programs to address key issues, for providing PRA-related advice and support to technical staff, for supporting PRA-related cooperative research activities with U.S. and international organizations, and for supporting technology transfer to other technical communities. He is currently providing technical oversight and leadership for research on vulnerability-related issues. Prior to joining the NRC, he was an Engineering Fellow at the Idaho National Engineering Laboratory (INEL). Prior to joining the INEL, he was an Associate Professor of Nuclear Engineering at the Massachusetts Institute of Technology. He has authored or co-authored over 150 technical papers and reports, and has served as co-editor for collections of invited papers on various topics.

Dr. Siu is a Fellow of the American Nuclear Society, a member of the IAPSAM Board of Directors (IAPSAM is the organization responsible for the bi-annual Probabilistic Safety Assessment and Management – PSAM – international technical conferences), and a Principal Member of the National Fire Protection Association Technical Committee on Fire Risk Assessment Methods. He has served on the Editorial Board of Reliability Engineering and System Safety.