<p>Plutonium accumulation from the operation of nuclear power plants presents a critical challenge for nuclear energy management, particularly due to the high decay heat and long-lived isotopes. The addition of plutonium as a thermal and fast reactor fuel material emerges as a potential strategy to reduce plutonium accumulation. The present study aims to investigate the fission reactor physics neutronic parameters such as infinite multiplication factors, reactivity coefficient, and kinetic parameters of the VVER-1000 fuel assembly with the addition of plutonium as a Mixed Plutonium–Uranium nitride fuel material, (Pu,U)N and (Pu,U)N + GdN. Neutronic calculations were carried out using MCNP6 with ENDF/B-VII.1 nuclear data library. The calculation results show that mixed Pu–U nitride fuel exhibits comparable safety characteristics to standard uranium oxide fuel material. Mixed Pu–U nitride fuel shows a better temperature coefficient of reactivity at the beginning of cycle compared to standard uranium oxide fuel_. With proper plutonium fraction adjustment for reactivity, mixed Pu–U nitride fuel can extend the fuel cycle length with its higher excess reactivity but low reactivity swing in fuel assembly level, compared to standard oxide fuel. Further study was needed to optimize the advantages of this fuel assembly in the reactor core. On the other hand, plutonium reduction for up to 19% for Pu-239 after 40 MWD/kg fuel burnup shows that plutonium utilization in the form of mixed Pu–U nitride fuel can be used to reduce the accumulation of plutonium.</p>