In the present study it was evaluated the diffusion radius of triple junctions of and tilt boundaries in Ni, obtained by crystallization, depending on the content of free volume. It is shown that diffusion in the area of triple junctions containing excess free volume proceeds much more intense than in the case when the additional vacancies were not introduced in the calculation block. In the boundaries and junctions formed by them during crystallization the free volume dissipated much more efficiently than in the junctions formed by the boundaries. For this reason the diffusion radius of the triple junction of boundaries at the introduction of 2 % conditional vacancies (about 3.5 Å) less than the radius of the junction of boundaries (4-5 Å).