  In the context of the ASAI (Astrochemical Surveys At IRAM) project, we
carried out an unbiased spectral survey in the millimeter window towards the
well known low-mass Class I source SVS13-A. The high sensitivity reached (3-12
mK) allowed us to detect at least 6 HDO broad (FWHM ~ 4-5 km/s) emission lines
with upper level energies up to Eu = 837 K. A non-LTE LVG analysis implies the
presence of very hot (150-260 K) and dense (> 3 10^7 cm-3) gas inside a small
radius ($\sim$ 25 AU) around the star, supporting, for the first time, the
occurrence of a hot corino around a Class I protostar.
  The temperature is higher than expected for water molecules are sublimated
from the icy dust mantles (~ 100 K). Although we cannot exclude we are observig
the effects of shocks and/or winds at such small scales, this could imply that
the observed HDO emission is tracing the water abundance jump expected at
temperatures ~ 220-250 K, when the activation barrier of the gas phase
reactions leading to the formation of water can be overcome. We derive X(HDO) ~
3 10-6, and a H2O deuteration > 1.5 10-2, suggesting that water deuteration
does not decrease as the protostar evolves from the Class 0 to the Class I
stage.
