The Versatile Test Reactor (VTR) is a new test reactor being designed under the DOE-NE, with the goal of bridging irradiation capabilities gaps in the United States. It will provide the highest fast neutron flux of any reactor, enabling accelerated testing of materials, fuels and other components for new reactors. It is designed as a versatile machine offering  capabilities to all advanced nuclear reactor technologies through the incorporation of cartridge loops allowing irradiation of materials with various types of coolants. At the conceptual design stage, it is a 300 MWth Sodium-cooled Fast Reactor able to achieve fast flux levels in excess of 4.3x10¹⁵ n/cm²-s, which is equivalent to >50 dpa per year.

Argonne is coordinating activities for the design of the nuclear core and safety analysis of the VTR, integrating efforts from other national laboratories in this area. Some of the relevant ongoing activities include maturation of the core design, code V&V, uncertainties quantification, system integration, thermal-hydraulics assessment, and shielding assessment.