Status of the Gd-water purification plant of the XENONnT Neutron Veto system.

One of the novel subsystems of the XENONnT experiment is the Neutron Veto, designed to reduce the neutron background by tagging them in a suited water Cerenkov detector. One of the key ingredients is the doping of water with gadolinium, the element with the highest neutron capture cross-section, in the form of $0.5%$ Gd-sulphate. In this contribution we will present the current status of the Gd-water purification plant, designed to maintain good optical properties of the solution, and the results of the "Reflectivity Monitor", which allows to check the performances of the detector, before and after the addition of Gd, in terms of transparency of the water and reflectivity of the walls.