No abstract

An electronic device that can raise the upper limit of detected gamma exposure from 5 mR/h up to 100 R/h, in the case of a high-pressure ionization chamber (HPIC), has been developed. The chamber has a 7 L sensitive volume filled with high-purity argon at 300 psi pressure and its current sensitivity is 16 nA/R/h. An empirical relationship between I and R has been used to program the electronic device. This device consists of an autoranging dc amplifier, an 8751 microcontroller, and an analog to digital converter/digital to analog converter. A single current reading obtained at 300 V is processed by the system to display the exposure rate instantaneously. Experiments have shown that the exposure rate values derived are comparable to the rates delivered within ±7.7%. The method has the advantage of using a single ion chamber over a very wide range and the device can be used with existing HPIC systems. Potential applications include area gamma monitoring in power reactors and other laboratories.