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The Virtual Environment for Reactor Applications (VERA)

The Virtual Environment for Reactor Applications (VERA) includes computational tools and supporting infrastructure that represent the cutting edge in light water reactor modeling and simulation, and can be used to solve neutronics, thermal-hydraulics, fuel performance, and coupled physics problems with advanced uncertainty quantification tools. VERA integrates physics components based on science-based models, state-of-the-art numerical methods, and modern computational science, and is verified and validated using data from operating PWRs, single-effect experiments, and integral tests. VERA is optimized for efficient execution on multiple platforms, including leadership-class computers, advanced architecture platforms now under development, and industrial engineering workstation clusters. CASL’s integrated, coupled solutions with VERA provide a more realistic representation of the reactor’s behavior. With VERA as its vehicle, CASL is developing and applying models, methods, data, and understanding to accelerate future advances in the development of this cleaner energy source.

VERA is available as a private distribution through the Radiation Safety Information Computing Center (RSICC). Distribution is currently limited to US citizens and legal permanent residents residing in the US under Test & Evaluation or Government Use license terms. VERA licensing is per individual; users must sign a license agreement and an export control agreement prior to receiving access to the code. CASL reserves the right to approve each request. The software package features extensive documentation that includes user, theory, verification & validation, and installation manuals.

Contact us at to start the request process. Please provide information regarding your intended usage of VERA and what compute resources you have available.

CASL's core simulator capabilities
Physics Model VERA Core Simulator Components
Neutron Transport 3D transport, 23+ energy groups
Power Distribution pin-by-pin, either homogenized or explicitly modeled
Xenon / Samarium pin-by-pin, either homogenized or explicitly modeled
Depletion pin-by-pin with actual core conditions
Reflector Models actual 3D geometry
Thermal Hydraulics subchannel with cross-flow
Fuel Temperatures pin-by-pin 2D or 3D
Fuel Performance science-based models for key performance phenomena
Target Platforms 32 – 300,000+ processing cores

System Requirements:

VERA is designed to run on Linux platforms with 32 or more cores. Detailed system software configuration and third party library requirements are specified in the Installation Guide provided with the code distribution.

User support links:

Questions, issues, bugs, and suggestions should be reported to Every effort will be made to respond to any requests within a reasonable period. Due to active development efforts, users may experience some delays.