Rehabilitation of broken-down chamber for the Gammacell-220 Irradiation Facility

The broken-down chamber of the gammacell-220 irradiation facility used for the calibration of dosimeters at the National Nuclear Research has been repaired. This repair work involved the identification of suitable components for the aluminum welding capable of ensuring double welding of the inside and outside joints of the chamber. Of paramount importance is the ability of the welded joint to physically sustain the safety column which is made of 26.9 kg of reinforce lead. The wielding was also expected to ensure that the shape of the chamber is retained after installation, apart from allowing uninhibited movement of the chamber which carries samples to be taken into the belly of the gamma cell for irradiation. The Ferrous ammonium sulfate (Fricke) solution was used as the dosimetry standard to check the gamma dose after restoration of the equipment. This report presents information on the procedure and justification for undertaking the repairs of this unit. By this successful repairs and putting into operation of the Gammacell-220, the maintenance team at the Center have demonstrated their ability to undertake similar works on the Gammacell-220 in the future even to other countries in the sub-region. (author). 2 refs., 2 figs