Performance of smart pressure transmitters under radiation ageing environment in NPPs

This paper presents the performance assessment of smart pressure transmitters subjected to accelerated radiation environment. Two transmitters were subjected to accelerated radiation ageing with a cumulative dose of 73 krad and 47 krad respectively at a dose rate of 1.878 k Gy/hr using cobalt-60 gamma radiation source. Investigation was mainly concerned about studying the performance parameters such as calibration, insulation resistance and power supply variation effects. It was observed during testing that one of the transmitters failed within 25 min of radiation aging. It was also evident that the sensor part of the transmitter was highly sensitive to gamma radiation which was found to be a major cause for change in the transmitter drift. A significant degradation was also observed in O-rings due to radiation ageing. A microscopic examination of hardware part of the circuit board was carried out and found significant degradation in the equipment circuit board which concludes to poor workmanship, manufacturing process and radiation effect.