b'I D A H O N A T I O N A L L A B O R A T O R Y F Y 2 0 2 0 L A B O V E R V I E WJokisaaris LDRD will further INLsL D R D S U C C E S S S T O R Y excellence in basic sciences of irradiation effects on materialsAndrea Jokisaari combines computational modeling and support the development andVTR conceptual design, developed using state-of-the-deployment of next-generationand simulation with experimental irradiationart digital engineering toolsreactors worldwideand characterization to understand and predictINL manages VTR for NEirradiation damage in uranium. She both advances fundamental scientific understanding of materialsVTR will be a 300 MWth pool-type sodium-cooled reactor fueled by a ternary metallic mechanisms and develops tools that can be used to(uranium-plutonium-zirconium) alloy. predict the behavior of metallic fuels for a variety ofVTR will provide a high fast-neutron flux reactors and conditions. for accelerated testing. The reactor core is designed to house next-generation test vehicles and experimental capabilities.When completed, VTR will be used to test F Y 1 9 I M PA C T fuels, materials, instrumentation, and sensors BISON, a simulation tool based on INLs user-developed andin the fast-neutron spectrum, which will open-source code Multiphysics Object-oriented Simulationfill a major gap in the U.S. nuclear energy RD&D infrastructure. When integrated Environment (MOOSE), was developed to predict the behaviorwith the capabilities of INLs existing RD&D of nuclear fuels and materials undergoing irradiation for nuclearinfrastructure, VTR will enable the U.S. to reactors under normal operating and accident conditions. Industryregain and sustain leadership in advanced interest and relevance of BISON and the complementary Marmotreactor technologies.platform was demonstrated by on-site training and user support at Westinghouse, General Atomics, Kairos Power, the ElectricThe VTR team includes five other national Power Research Institute, and the Nuclear Regulatory Commission.laboratories, 20 universities, and multiple BISON predictions of U Siaccident tolerant fuel fuel swellingprivate companies. Mission need for VTR was 3 2 approved in February 2019. In August 2020, and fission gas release behavior were significantly improved by parameterization from Marmot lower length-scale simulations, aBEA initiated contract negotiations with a demonstration that such parameters can be determined quicklyteam led by Bechtel National Inc., including for new fuels using lower length scale simulations. Kairos PowerTerraPower and GE Hitachi Nuclear Energy, announced to the Nuclear Regulatory Commission their intentto support the design and build phase of the to use BISON for the design and licensing of their tristructuralVTR. In September 2020, DOE announced that isotropic (TRISO) particle fuel technology. it had approved Critical Decision 1, known as Approve Alternative Selection and Cost Range, the second step in the formal process The Marmot simulation of accidentDOE uses to review and manage research tolerant fuel gas bubbles on a grain boundary provides more accurateinfrastructure projects. The target date forinformation about core temperatures helping engineers make nuclearVTR operations is 2026.reactors safer and more reliable7'