The hyperfine interaction constants of the triplet (3d2)3P states of Sell are calculated using Rayieigh-Schr?dinger perturbation method. The core polarizations are included to all orders using a recurrence formula and the correlations to low orders. The results are compared with experimental data and MCDF calculations of Young et al. It is found that the core polarization (especially the spin polarization) has drastic effects on the magnetic dipole interaction constant. Our results for constant A (MHz) are-116.667 and -12.442 for 3P1 and 3P2 states respectively, that of the experiments are-107.3(6) and -27.7(8), whereas the MCDF calculations of Young et al. obtained-1.8 and 85.9.