The nuclear transmutation is the only way to reduce the radioactive hazard of the high level long-lived radioactive minor actinides (MA). The majority of commercial reactors in operation in the world are pressurized water reactor (PWRs), hence the transmutation efficiency of minor actinide nuclide (MA) in PWR are crucial problem in the area of the nuclear waste disposal.

This study aims to improve the transmutation efficiency of MA and flatten the core power distribution by using MA nuclide for PWR.

First of all, the HPR1000 (Hualong #1) model 177 core structure was taken as reference PWR, thermal-fast neutron convertible material ⁶LiD was introduced to design coated axially non-uniform MA/⁶LiD transmutation rods which structurally applicable to the PWR. The internal component of the transmutation rods was UO₂, and the external component was the transmutation coating material composed of MA and ⁶LiD nuclides. The layout of the coating material on the transmutation rods was axially three, five and seven segments structure, and the coating thickness gradually decreased from the middle to both ends. Then, the Monte Carlo program RMC2.0 developed by the Reactor Engineering Calculation and Analysis Laboratory of Tsinghua University was employed to establish the core and calculate the effect of transmutation coating material composition on core k_eff.

The results show the best transmutation effect up to 23.25% is realized when the mass ratio of ⁶LiD to MA in the transmutation coating material is 2∶8. Among the coated axially nonuniform transmutation rods, the seven-segment transmutation rod has the best transmutation effect, and the transmutation rate is 25.43%. The best fission effect of three-segment transmutation rod has the fission rate of 4.48% for MA nuclide. At the same time, the transmutation rod with axial non-uniform structure can reduce the axial power peak factor of the core from 1.778 to 1.375.

Compared with axially uniform rods, these axially non-uniform MA/⁶LiD transmutation rods have good transmutation efficiency, especially the fission rate, and good performance on flatten axial power distribution is achieved, simutanously.