  We calculate the O(alpha_s) radiative corrections to the three spin
independent and five spin dependent structure functions that describe the
angular decay distribution in the decay of a polarized top quark into a W-boson
(followed by the decay W^{+} -> l^{+} + nu_l or by W^{+} -> anti-q + q and a
bottom quark. The angular decay distribution is described in cascade fashion,
i.e. the decay t(uparrow) -> W^{+} + X_b is analyzed in the top rest system
while the subsequent decay W^{+} -> l^{+} + nu_l (or W^{+} -> anti-q + q) is
analyzed in the W rest frame. We present our results for the eight O(alpha_s)
integrated structure functions in analytical form keeping the mass of the
bottom quark finite. In the limit m_b -> 0 the structure function expressions
reduce to rather compact forms.
