To study the applicability of utilization of Inert Matrix fuels (IMF) in PWR, the variations of infinite multiplication factor kinf, fuel temperature coefficient Dc, moderator temperature coefficient MTC with PuO2 volume fractions in two typical IMF fuels, PuO2+ZrO2+MgO and PuO2+ThO2, are calculated and analyzed. And the preliminary acceptable design regions of IMF fuels composition to satisfy the negative Dc and MTC are obtained. ©, ...