Year
1993
Abstract
The gain of a portable low resolution BGO detector-PMCA measurement system, used to make holdup measurements in a manufacturing plant environment, is sensitive to fluctuations in ambient temperature. To ensure reliable measurements in the field, operators had to periodically measure a standard radioactive source and manually adjust the gain to meet established acceptable criteria. Failure to meet the measurement control criteria resulted in repeating all measurements acquired since the previous acceptable measurement control check. An automatic temperature compensation system was developed by characterizing the PMCA gain response as a function of temperature and establishing a software-controlled temperature compensation program. A voltage-independent temperature transducer is mounted in the BGO probe. Prior to taking an actual measurement, the software checks the temperature of the probe sensor and adjusts the PMCA gain according to the response curve. The frequency of periodic gain checks is reduced, which reduces the overall measurement time. Measurement control failures have almost been eliminated, reducing the need to make repeat measurements. The apparent significant improvement in measurement precision will be verified by future studies. The measurement system can be used over the temperature range of 0 to 40 °C.