Radiachromic: A radiation monitoring system

Abstract

Radiation measurement and radiation monitoring are vitally important elements of a radiation processing program. This includes both the basic calibration of the ‘free field’ and the routine monitoring of the facility during operation. A basic calibration may use time-consuming, arduous, and expensive methods for initial primary standard measurements. In contrast, an on-going quality control system should be compact, rugged, simple to use, and relatively inexpensive. It should have the capability of yielding highly reproducible measurements that can be related to the basic calibration data. It would be desirable to use the same system for routine monitoring of process lines, as well as for complete mapping under operating conditions. Various plastic film materials have been utilized to measure radiation fields. The radiachromic materials have been found to have advantages in reproductibility, stability, equivalent response to electrons and gamma ray fields, dose rate independence and negligible variation for most environmental parameters. A simple photometer has been developed for read-out. The physical and chemical properties of the total system are described. A standard radiachromic has been selected for application to radiation processing. This material has a dose range of 5 × 10 4 to 3 × 10 7 rads, no dose rate effects to above 4 × 10 14 R/sec, an equivalent response to electrons and gamma rays, shelf life of greater than one year. Other forms are also applicable to radiation processing.