Nuclear Energy

Meet the RELAP5-3D Team

Meet the researchers and engineers who develop, maintain and advance RELAP5-3D while supporting nuclear reactor analysis, software development and user applications.

IRUG Team Photo containing 5 individuals
Portrait: Piyush Sabharwall

Dr. Piyush Sabharwall

Irradiation Experiment Thermal Hydraulics Analysis Manager

Portrait: George Mesina

Dr. George Mesina

Acting manager for Thermal Fluids Systems, Methods & Analysis

connie stevens

Connie Stevens

Project Coordinator
Mauricio Eduardo Tano Retamales

Dr. Mauricio Tano Retamales

Staff Scientist

RELAP5 team portraits: Carlo Parisi

Dr. Carlo Parisi

Nuclear Engineer

Portrait: Jan Vermaak

Dr. Jan Vermaak

Senior Nuclear Multiphysics Engineer

RELAP5 team portraits: Brandon Cox

Brandon Cox

Engineer & Software Developer

RELAP5 team portraits: Victor Leite

Dr. Victor Coppo Leite

Researcher

Dr. Ishita Trivedi

Computational Scientist

Portrait: Robert Kile

Dr. Robert Kile

Advanced Reactor Research & Development Engineer

Connect with our Team

Questions about our research, capabilities or collaboration opportunities?
Our team is ready to connect you with the right experts and resources at INL.

Contact Us

Program Manager: R53DProgramManager@inl.gov

Project Coordinator: R53DProject.Coordinator@inl.gov​

Custodian: R53DCodeCustodian@inl.gov

Developers: R53DCode.Developers@inl.gov

Portrait: Piyush Sabharwall

Piyush Sabharwall

Irradiation Experiment Thermal Hydraulics Analysis Manager

Sabharwall is a distinguished staff scientist in the Nuclear Science and Technology directorate at the Idaho National Laboratory with more than 20 years of research and development experience. On June 24, 2024, he became manager of the department containing the RELAP5-3D program. He is a recognized expert in the design and safety of nuclear systems, with specialized knowledge in thermal-hydraulics, heat transfer, compact heat exchanger design and thermal energy systems. Sabharwall is the technical area lead on the U.S. Department of Energy Office of Nuclear Energy’s Microreactor R&D Program, the Holtec Small Modular Reactor 300 Advanced Reactor Demonstration Project and has led the development of a gas-cooled cartridge loop for the Versatile Test Reactor. In his current role as Thermal Fluid Systems Methods and Analysis department manager, he leads INL’s thermal hydraulics research supporting and guiding development of system code such as RELAP5, MOOSE-based tools such as SAM and Pronghorn, and leads the development of thermal-hydraulic validation experiments assisting with accelerated development and deployment of advanced reactor technologies. He has consulted for industries, both nationally and internationally, building technical expertise with an additional focus on market studies and economic viability to rebuild U.S. nuclear industrial infrastructure and position the U.S. industry to continue its leadership in the global energy market.

Portrait: George Mesina

Dr. George Mesina

Acting manager for Thermal Fluids Systems, Methods & Analysis

Dr. George Mesina earned his PhD in Applied Mathematics in 1988 from the University of Pittsburgh. He has served as the RELAP5-3D Code Architect for 25 years. He is the acting manager for INL’s Thermal Fluids Systems, Methods, and Analysis department, responsible for the RELAP5-3D code analysts and developers and leading the RELAP program.

connie stevens

Connie Stevens

Project Coordinator

Ms. Connie Stevens works as the RELAP5-3D project coordinator. She received a Master of Legal Studies from the University of Utah S.J. Quinney College of Law, and a B.Sc. in Applied Management from Brigham Young University-Idaho. Connie’s work is currently focused on building and strengthening relationships with domestic and international RELAP5-3D license holders, leading the organization of the annual International RELAP5 User Group (IRUG) meeting, and providing program management support to the department manager and RELAP5 team.

Mauricio Eduardo Tano Retamales

Mauricio Tano Retamales

Staff Scientist

Dr. Mauricio Tano-Retamales is a Staff Scientist in the Thermal Fluids Systems and Methods Analysis group at Idaho National Laboratory (INL). He currently leads efforts for high- and intermediate-fidelity modeling and simulation of multiphysics phenomena in advanced nuclear reactors, which include the development of models coupling between neutronics, thermal-hydraulics, thermomechanics, salt chemistry, and corrosion. Additionally, Dr. Tano-Retamales is an active developer of INL’s coarse-mesh computational fluid dynamics (CFD) code Pronghorn and INL’s MOOSE-based subchannel code for advanced nuclear reactors. Dr. Tano-Retamales leads the coupling between RELAP5-3D and CFD codes and performs nuclear reactor analyses using RELAP5-3D. 

RELAP5 team portraits: Carlo Parisi

Dr. Carlo Parisi

Nuclear Engineer

Dr. Carlo Parisi holds a MSc and PhD in nuclear engineering from Pisa University, Italy. He joined INL in 2015, and since then he has worked on the Light Water Reactor Sustainability (LWRS) program, Versatile Test Reactor (VTR) and improved Advanced Test Reactor (ATR) concepts, and the sodium loop for the TREAT reactor. Since 2020 he is responsible for the thermal hydraulic design of the microreactor “MARVEL”.

RELAP5 team portraits: Jan Vermaak

Dr. Jan Vermaak

Senior Nuclear Multiphysics Engineer

Jan Vermaak joined INL in 2022 as a Senior Nuclear Multiphysics Engineer. He has 14 years of diverse experience in reactor engineering ranging from nuclear safety analysis to managing reactor engineering at the Texas A&M University TRIGA reactor. He holds a bachelor’s degree in mechanical engineering and a master’s and PhD in nuclear engineering. Jan’s current work is focused on code development and analysis in the fields of neutronics, computational fluid dynamics (CFD), thermal-hydraulics, mechanical stress, and nuclear fuel performance.

RELAP5 team portraits: Brandon Cox

Brandon Cox

Engineer & Software Developer

Brandon Cox is an engineer and software developer in the Thermal Fluid System Methods & Analysis Department at Idaho National Laboratory. In 2019 he graduated from Brigham Young University with a B.S. in Chemical Engineering. He has experience developing engineering software and computational fluid dynamics (CFD). He is currently a RELAP5-3D Developer and Analyst. In this capacity, he participates in various RELAP5-3D updates and development activities and corrects user errors. He also performs engineering calculations and analyses using RELAP5-3D and CFD. He has experience using Python, Fortran, Linux, and OpenFOAM. Outside of work he enjoys spending time with family and many outdoor activities including hiking, hunting, fishing, and photography.

 
 

RELAP5 team portraits: Victor Leite

Dr. Victor Coppo Leite

Researcher

Dr. Victor Coppo Leite is a researcher at Idaho National Laboratory who recently earned a Ph.D. in Nuclear Engineering from Pennsylvania State University. He also holds a Bachelor of Science and a Master of Science in the same field from the Federal University of Rio de Janeiro. His interests include incorporating machine learning methods into thermal hydraulic problems and multi-physics modeling. Currently, he applies his expertise to contribute to the development of RELAP5-3D, while also engaging in activities to maintain the code and conduct analyses.

 

Dr. Ishita Trivedi

Computational Scientist

Dr. Ishita Trivedi works as a computational scientist in the Advanced Reactor Design & Technology at Idaho National Laboratory (INL). She received her PhD in Nuclear Engineering from North Carolina State University focusing on Uncertainty Quantification and Propagation Methods for Safety Analysis of Lead-cooled Fast Reactors. Ishita also has a M.Sc. and B.Sc. in Nuclear Engineering from North Carolina State University and Pennsylvania State University, respectively. At INL, Ishita is involved in several advanced reactor multi-physics analysis projects including leading the MARVEL criticality benchmark development, nuclear thermal propulsion reactor modeling and simulation among other projects. Ishita also works in software quality assurance, validation & verification of INL applications.

Portrait: Robert Kile

Dr. Robert Kile

Advanced Reactor Research and Development Engineer

Dr. Robert Kile is an Advanced Reactor Research and Development Engineer at Idaho National Laboratory. His work focuses on code validation for gas-cooled reactors. Dr. Kile is also the coordinator for the Depressurized Conduction Cooldown problem of the OECD-NEA HTTF Benchmark.