  We investigate transport and shot noise in lateral N-TI-S contacts, where N
is a normal metal, TI is a Bi-based three dimensional topological insulator (3D
TI), and S is an s-type superconductor. In normal state, the devices are in the
elastic diffusive transport regime, as demonstrated by a nearly universal value
of the shot noise Fano factor $F_{\rm N}\approx1/3$ in magnetic field and in
reference normal contact. In the absence of magnetic field, we identify the
Andreev reflection (AR) regime, which gives rise to the effective charge
doubling in shot noise measurements. Surprisingly, the Fano factor $F_{\rm
AR}\approx0.22\pm0.02$ is considerably reduced in the AR regime compared to
$F_{\rm N}$, in contrast to previous AR experiments in normal metals and
semiconductors. We suggest that this effect is related to a finite thermal
conduction of the proximized, superconducting TI owing to a residual density of
states at low energies.
