Approval and control of radiation processes, EB and gamma

The documentation which is needed for approval of radiation treated products includes a facility description and an initial plant commissioning procedure. The description of the facility must put particular emphasis on those parameters, which in effect determines the dose in the product. For a gamma plant these are source strength and geometry, product conveyor geometry and mode of transport, and in a similar manner for electron accelerator plants, the beam characteristics, power and geometry, and product transport parameters. The initial commissioning concerns measurement of dose and dose distribution in a reference product, and of procedures, which describe how traceability of these measurements to primary standards is obtained. Commissioning measurements must be repeated whenever major changes of the facility are made. In order to maintain the correct dose, a routine monitoring system must be established. This consists of measurement and recording of the process parameters, and of routine dosimetry. For a gamma plant, the most important (and sometimes the only) variable parameter is the product speed (or dwell time), while for electron beam plants, the beam parameters must also be recorded. For approval of individual processes or products, it is necessary to demonstrate that the dose within the actual product is within the process design limits. Measurement of dose distribution is therefore needed in order to locate minimum and maximum dose points, and subsequently it is needed to determine the variability of dose at these points. (author)