WSC has completed the upgrade of Zaporizhzhya Nuclear Power Plant Unit 1 Full-Scope Simulator in Ukraine. WSC developed and replaced all primary, secondary, balance of plant, and auxiliary systems, including the electrical system models, using the 3KEYMASTER state-of-the-art environment and modeling tools. The Reactor Primary Systems Thermal-Hydraulic and Neutronics models were upgraded using Idaho National Laboratory (INL) RELAP5-RT and NESTLE. The scope of the hardware upgrade included replacing the aged fleet of computers and upgrading the obsolete interface between the main servers and the panel Input/output (I/O) system. The Unit 1 full-scope simulator is currently in Pilot Operation, and WSC looks forward to a long-term relationship with the Zaporizhzhya plant based on their forthcoming modernization FSSs for Unit 3 and Unit 5.