Absorbed dose and operation time as parameters of the P.I.BA operation

The PIBA (BArros Irradiation Plant), a sewage irradiation plant has being built at Tucuman (Argentina) the National Commission of Atomic Energy. It is designed for insure an absorbed dose of 2 kGy (3 kGy without oxygenation) to 140 m3/day of sludge by gamma irradiation from 60 Co sources. To guarantee that almost all the volume of the irradiate sludge had absorbed at least the fixed dose is more important that its volume uniformity since the desired effect of the treatment is to produce a harmless sewage in respect to the risk diseases. The objective of this work is the calculation if the absorbed dose related to the irradiation time, the operation time and the sources geometry and activity. Mathematical models are developed for obtaining the volume distribution of the absorbed dose. An absorbed dose ≥ 2 kGy is required for the 99.8% of the irradiated sludge volume. Achieving the threshold dose depends upon the total activity which determines the daily time of operation. A numerical set of the major interrelated parameters is given for the efficient operation of the PIBA. (author). 5 refs., 3 figs., 1 tab