Neutronics performance of the previously mentioned three FA designs is studied, particularly the power peaking factor and the reactivity varying with the FA burnup. The evaluation conditions, which have been determined from the core average, are as follows: the density of the moderator and the coolant is 0.58 g/cm^{3} and 0.3 g/cm^{3}, respectively, and the average fuel temperature is 830 °C without control rods. The k-inf and power peaking factor of the three FA design varies with burnup is given by Figs. 3 and 4. Figure 3 shows that the expected discharge burnup of the two FA with the average enrichment of 7.8% reaches to 60,000 MW d/t(U) from the viewpoint of core criticality, which is a theoretical burnup without considering the radiation effect and the mechanical performance. This burnup is much higher than that of the conceptual design with 5.7% average enrichment fuel, and satisfies the tentative target of 20 months or even longer refueling cycle. In addition, due to the addition of burnable poison Er_{2}O_{3}, the curve of reactivity variation is more flat than that of the conceptual design. Figure 4 shows that the peaking factor of the FA is decreased by using three region fuel rods with different enrichments. The maximum power peaking factor of FA is 1.04, which is much lower than that of the conceptual design (1.11), and the power peaking factor of FA is kept between 1.03 and 1.04 with the variation of burnup. The lower and more flat power peaking factor lays a foundation for the core optimization.