  We consider the role of quantum effects in the non-perturbative decay of
non-abelian string with orientational moduli in non-supersymmetric D=4 gauge
theory. To this aim the effective action in the $CP(N-1)$ model on a disc at
large N has been calculated. It exhibits phase transition at some radius, the
"wrong sign" Luscher term and large boundary boojum-like negative contribution.
The effect of $\theta$ - term and the possibility of the spontaneous creation
of the non-abelian string are briefly discussed.
