In August 2019, through a contract by Battelle Energy Alliance (BEA), WSC also delivered a full simulator upgrade for Idaho National Labs Advanced Test Reactor (ATR) Simulator. WSC fully replaced the environment and models, including the reactor neutronics and thermal hydraulics, with our 3KEYMASTER simulation system and modeling tools. WSC also teamed with Studsvik of America to provide the ATR's serpentine-shaped core model using their RAMONA code. In addition to upgrading the environment and models, WSC improved the modeling of the radiation transport to allow a more integrated environment with a DRMS (radiation monitoring system) currently being installed, and provided interfaces with the MaxDNA virtual control system and the stimulated systems (CDS, IO and the DRMS). The updated simulator includes a full set of soft panel graphics that mimics the ATR control room panels. The 3KEYMASTER Instructor Station provides access to thousands of generic malfunctions and custom malfunctions unique to the ATR and access to visually dynamic diagrams of all modeled systems.