Investigation on the behaviour of Fe++ and Cu++ chemical dosimeter under process conditions, including the influence of solute concentration in the system

The reaction mechanism proposed for the Fe-Cu dosemeter in the literature has failed to explain why the yield of Fe+++ is not a linear function of dose and why there is a difference in the initial yield when the solution is oxygen saturated as opposed to oxygen depleted. In addition, an investigation of the dose-rate effect on G(Fe+++) in oxygenated and oxygen depleted solutions yields results which have not proved amenable to the introduction of new reaction mechanisms. Pulse radiolysis studies have also failed to provide insight into additional reaction mechanisms which would explain the various discrepancies in the radiological behavior of the Fe-Cu system. In the present work, the Fe-Cu system was studied under extreme conditions of solute concentration and dose-rate. The experiments were aimed at determining the influence of concentrations of O2, Fe++, Fe+++ and Cu++ on the yield of Fe+++ in the irradiated Fe++-Cu++ dosemeter solution. Rapid mixing techniques were employed and a model reaction scheme developed for computer calculations to test the understanding of the radiochemical reactions. Methods for suppressing the reactions Cu++O2→Cu+++O2- and HO2+Fe++→HO2-+Fe+++ and thus improving dosemeter performance in a gamma field were determined. However, the investigation demonstrated that the dosemeter cannot be used for high dose-rate dosimetry of pulsed electron beams