Modeling of Safety Basis Events in the VTR

The Versatile Test Reactor (VTR) is a fast spectrum test reactor currently being developed in the United States under the direction of the U.S. Department of Energy, Office of Nuclear Energy. Safety analysis of the conceptual VTR design is being performed using the SAS4A/SASSYS-1 fast reactor safety analysis code with a model representing the reactor core, primary and secondary heat transport systems, reactor vessel auxiliary cooling system, and reactor protection system. The system’s response and safety performance are being evaluated for a wide spectrum of event initiators and accident sequences. This paper presents an overview of the activities that are ongoing in support of the modeling and analysis of safety basis events (SBEs) in the VTR, including the VTR SAS4A/SASSYS-1 model development, an overview of the SAS4A/SASSYS-1 verification and validation efforts, and a summary of key model development activities to improve the predictive capability of the code. A summary of the results and an analysis of several key SBEs are also presented. VTR authorization from the U.S. Department of Energy will require transient simulations that are demonstrated to be accurate.