This paper evaluates the neutronic feasibility and multi-physics safety of a hybrid Accident Tolerant Fuel (ATF) assembly in a VVER-1000 reactor. The proposed design strategically employs standard UO2 within the inner core and a high-density U3Si2 matrix in the peripheral pins to take advantage of inter-assembly thermalization for cycle length extension. Coupled evaluations were performed using OpenMC continuous-energy Monte Carlo transport and OpenFOAM steady-state conjugate heat transfer Compu