A NEW-GENERATION OF TRACK ETCHED MEMBRANES FOR MICROFILTRATION AND ULTRAFILTRATION .1. PREPARATION AND CHARACTERIZATION

A new experimental apparatus for porous track etched membrane producti on has been designed, tested and installed near the core of the IEA-R1 nuclear reactor at IPEN-Sao Paulo. The thermal neutron flux close to the centre of the reactor core has been used to produce fission fragme nts from uranium sample which was deposited on a rod located at the ce ntre of an evacuated aluminium chamber. These nuclear fragments imping e on a polycarbonate film mounted on the inner cylindrical wall of the irradiation chamber. Under conditions of uniform neutron flux large a reas of track etched membranes, with high level of pore uniformity, ha ve been produced in the micro and ultrafiltration range. Membranes wit h pore diameters ranging from 15 to 100 nm. have been prepared reprodu cibly, based upon a calibration curve of track diameter versus etching time.