Improvements to In-Canal Assay of High Specific Activity 60 Co at the Advanced Test Reactor

Improvements to the quality of measurements in the assaying of high specific activity (HSA) 60Co produced at the Advanced Test Reactor (ATR) at the Idaho National Laboratory are reported. Such assays are conducted regularly between cycles at the ATR, and because of radiological safety concerns, they are performed within the ATR canal. A standard ion chamber detector is placed in a collimated assay tube within the canal. Another tube, parallel to the detector, is used to position various 60Co standards and targets. The collimated port between these tubes allows for the targets to be pulled across the collimator via a winch system. Previous measurements were performed at discrete 1.5-in. steps using a hand-cranked winch system. Charge was collected and integrated for 10 s at each discrete step during a scan. Two substantial improvements to the assay include an electronically controlled, motor-driven winch system and a software-controlled continuous charge collection. Combined, these changes improved the quality of measurements as well as streamlined the assay process.