CASL members TVA, Westinghouse, and Oak Ridge National Laboratory have successfully completed a detailed simulation of the initial startup of Watts Bar Nuclear Unit 2 (WBN2) using the advanced reactor simulation tools known as VERA. WBN2 is the first commercial power reactor to join the nation's electrical grid in over two decades, and the modern core design and availability of data make it an excellent benchmark for CASL. Calculations were performed three months prior to the startup, and in the first blind application of VERA to a new reactor, predicted criticality and physics parameters very close to those later measured by TVA. Subsequent calculations with the latest version of VERA and using exact measurement conditions improved the results even further. The escalation to full power required approximately five months, including several intermediate testing power plateaus. The entire power, temperature, and control rod history was simulated with VERA by the hour, requiring 4,130 time steps, and included isotopic depletion and decay through ten additional shutdown intervals. TVA provided the startup data, as well as measured boron concentrations, reactor temperatures, ex-core axial flux difference (AFD), and twelve measured incore neutron flux distributions. The entire simulation required 892,837 core-hours, or 13.5 days on 2,784 cores. This included 16,605 neutronics/thermal-hydraulic iterations.