Sunil S. Chirayath


Sunil S. Chirayath


Nuclear Safety, Security and Safeguards (3S) of Nuclear Fuel CycleMonte Carlo Radiation Transport


Prof. Chirayath is the Director of the Center for Nuclear Security Science & Policy Initiatives (NSSPI) at Texas A&M University with a joint appointment of Associate Professor of Nuclear Engineering. His B.Sc., M.Sc., and Ph.D. degrees are in Physics. Previous positions include: Scientific Assistant, Indian Atomic Energy Regulatory Board, Mumbai (1991 - 1998); Scientific Officer, Indian Atomic Energy Regulatory Board, Kalpakkam (1998 - 2007); Postdoctoral Research Associate, Texas A&M University (2007 - 2010); Research Scientist, Texas A&M University (2010 - 2014), Associate Director-NSSPI (2014-2015). He has more than 28 years of experience in Nuclear Science and Engineering research, education and training with specialization in nuclear safety, security and safeguards. He teaches courses on nuclear fuel cycle and nuclear material safeguards, nuclear security and Monte Carlo radiation transport. Research interests include safeguards approaches for nuclear fuel cycle, proliferation resistance quantification & analysis, nuclear forensics, nuclear security insider threat analysis, fast breeder reactor analysis and small modular reactor neutronics coupling with thermal hydraulics. In current position, manages and directs projects funded by USDHS and USDOE, USDOS and nuclear utility companies. Has conducted nuclear security educational programs in the US and abroad for faculty and professionals. He has over 150 technical publications in referred journals (41) and peer reviewed (23) and other conference proceedings (95). He has supervised more than 34 MS thesis and PhD dissertation research of students (including 13 current students), most of them conducting research in the area of nuclear nonproliferation. He has also supervised 5 postdoctoral research associates in the nuclear nonproliferation subject area.


Collaborative work in the area of innovative Molten Salt Reactor design and nuclear safeguards approaches by combining the capabilities of the Texas A&M center for Nuclear Security Science and Policy Initiatives (NSSPI) and the Tokyo Institute of Technology Laboratory of Advanced Nuclear Energy (LANE).


  • Experimental and Computational Assessment of Unique Trace Elements and Isotope Ratios in Plutonium from Depleted Uranium Irradiated in Fast Reactor Blankets

    This project is a five-year, multi-disciplinary effort, led by the Center for Nuclear Security Science and Policy Initiatives (NSSPI) of the Texas Engineering Experiment Station (TEES) at Texas A&M University (TAMU). The overall purpose of this project was to use computational and experimental methods to determine whether it is possible to reliably predict and measure a unique intrinsic physical signature in weapons-grade plutonium (Pu) produced in reactors of foreign nuclear fuel cycles. The particular fuel types of interest are fast breeder reactor (FBR) depleted uranium blankets and CANDU-type reactor natural uranium fuel.

    Project Objectives and Impact
    1. Fingerprinting weapon-grade plutonium produced in fast breeder reactor (FBR) blankets and thermal reactor (CANDU reactor) low-burned fuel (1GWd/t).
    2. Experimental validation of weapon-grade Pu fingerprints originating from unique nuclear fuel cycles.
    3. Development of a national nuclear forensics capability for targeting weapon-grade plutonium produced from low burned fuel assemblies in foreign nuclear fuel cycles.
    4. Separation of plutonium from fission products and uranium using PUREX and characterization of this Pu by destructive and nondestructive analyses; these results will be highly valuable as teaching and demonstration tools for graduate and undergraduate students.
    5. Mentoring, educating and supporting postdoctoral researcher, graduate and undergraduate students.
    6. Publications through student presentations in technical conferences and scholarly journals.

    - Periods: 2011-2016
    - Funding source: US National Science Foundation and US Department of Homeland Security
    - Members: Prof. Charles M. Folden III

    Plutonium source attributionMaximum likelihood data analyticsPUREX decontamination factors


Specially Appointed Associate Professor, Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology


Associate Professor, Department of Nuclear Engineering, Texas A&M University


Director, Texas A&M Center for Nuclear Security Science and Policy Initiatives (NSSPI), Texas A&M University


Research Assistant Professor, Department of Nuclear Engineering, Texas A&M University


Interim Director, NSSPI, Texas A&M University


Associate Director, NSSPI, Texas A&M University


Research Scientist, NSSPI, Texas A&M University


Visiting Assistant Professor, Department of Nuclear Engineering, Texas A&M University


Postdoctoral Research Associate, NSSPI, Texas A&M University


Scientific Officer, Indian Atomic Energy Regulatory Board, Mumbai and Kalpakkam


Scientific Assistant, Indian Atomic Energy Regulatory Board, Mumbai


Stipendiary One-year Trainee, Bhabha Atomic Research Center, Mumbai and Tarapur


Senior Member of the Institute of Nuclear Materials Management (INMM)


Honorary Professor at Amity Institute of Nuclear Science and Technology, Amity University, Uttar Pradesh, India

Academic Year 2011-2012

Outstanding Faculty Award: Texas A&M Nuclear Engineering Department


S. S. CHIRAYATH, J. M. OSBORN, and T.M. COLES, “Trace Fission Product Ratios for Nuclear Forensics Attribution of Weapons-Grade Plutonium from Fast and Thermal Reactors,” Science and Global Security, 23 (1), 48-67


S. S. CHIRAYATH, R. ELMORE, G. HOLLENBECK, N. CHANDREGOWDA, W.S. CHARTLON, R. METCALF, J. RAGUSA, “Proliferation Resistance Analysis and Evaluation Tool for Observed Risk (PRAETOR) – Methodology Development,” Journal of Nuclear Materials Management, 43 (2), 22-36


P.M. MENDOZA, S.S. CHIRAYATH, and C.M. FOLDEN III, “Fission Product Decontamination Factors for Plutonium Separated by PUREX from Low-Burnup Fast Neutron Irradiated Depleted UO2”, Applied Radiation and Isotopes, 118, 38-42


M.A. HAWILA and S.S. CHIRAYATH, “Nuclear Security Risk Analysis: An Insider-Outsider Collusion Scenario”, International Journal of Nuclear Security, 2 (2)


E. D. KITCHER* and S.S. CHIRAYATH, “A Neutron Transport and Thermal Hydraulics Coupling Scheme to Study Xenon Induced Power Oscillations in a Nuclear Reactor”, Annals of Nuclear Energy, 106, 64-70


M.W. SWINNEY, C.M. FOLDEN III, R.J. ELLIS, and S.S. CHIRAYATH, “Experimental and Computational Forensics Characterization of Weapons-grade Plutonium Produced in a Fast Reactor Neutron Environment”, Nuclear Technology, 197 (1), 1-11


J.M. OSBORN, E.D. KITCHER, J.D. BURNS, C.M. FOLDEN III, and S.S. CHIRAYATH, “Nuclear Forensics Methodology for Reactor-Type Attribution of Chemically Separated Plutonium”, Nuclear Technology, 201, 1-10


M.A. HAWILA and S.S. CHIRAYATH, “Combined Nuclear Safety-Security Risk Analysis Methodology Development and Demonstration through a Case Study”, Progress in Nuclear Energy, 105, 153-159


S.M. WOO, and S.S. CHIRAYATH, “Evaluation of Nuclear Material Accountability by the Probability of Detection for Loss of Pu (LOPu) Scenarios in Pyroprocessing”, Nuclear Engineering Technology, 51 (1), 198-206


J.M. OSBORN, K.J. GLENNON, E.D. KITCHER, J.D. BURNS, C.M. FOLDEN III, and S.S. CHIRAYATH, “Experimental Validation of a Nuclear Forensics Methodology for Source Reactor-Type Discrimination of Chemically Separated Plutonium”, Nuclear Engineering Technology, 51 (2), 384-393