The Korea Atomic Energy Research Institute (KAERI) says it has developed a new technique for the world's first nuclide separation device that employs robots and sensors.
To safely manage radioactive waste, radionuclide analysis must be conducted to determine what radionuclides are present within it. There are three processes involved including preprocessing, separation, and measurement.
Nuclide separation is the process of adding a reagent that reacts with a specific nuclide to a sample of melted radioactive waste. This process is repeated to separate each nuclide. Current techniques include a manual method of adding the reagent to a separation container by gravity and an automatic method using a pump.
The manual method is unable to control the speed of the reagent, the KAERI notes, and the automatic method has the disadvantage of having complex components such as pumps, valves, and numerous tubes connected to the valves. The valves must be activated according to a predetermined sequence. In particular, the automatic method requires cleaning each time it is used to ensure that no radioactive materials remain in the valves that control the injection of the reagent and the tubes through which the reagent moves.
The KAERI says that the separation device it has developed uses an automatic method. A liquid handling robot that does not come into contact with radioactive samples inserts reagents as needed. The radioactive samples separated by the reagent reaction are each collected for the next measurement process. Due to the use of the robot, there is no need for a valve that can cause residual materials or blockages. The number of tubes used has also been drastically reduced. This makes it possible to easily replace components that come into contact with radioactive samples. It completely eliminates the possibility of cross-contamination due to residual samples.
A non-contact sensor has been applied to the nuclide separation vessel for the first time. This sensor detects when all the reagents have been injected. It then notifies the operator in real time that the process of adsorbing or separating the nuclide into the adsorbent inside the separation vessel is complete. This allows more accurate separation than the existing method of operating the pump for a set period of time.
The KAERI says that the new device can efficiently sequentially separate technetium-99, strontium-90, iron-55, niobium-94, and nickel-59 and nickel-63 from a single sample. An effectiveness evaluation conducted in cooperation with the KAERI's Radioactive Waste Chemical Analysis Centre, found that technetium, strontium, niobium and nickel were separated three times faster than the existing method. This achieved a high nuclide recovery rate of eighty-three to ninety-seven percent. In contrast to the existing method, iron was able to react about thirty three percent longer by precisely controlling the amount and speed of the reagent, resulting in better and more precise results.
Ryu Jae-soo is the head of KAERI's Advanced Nuclear Cycle Technology Development Division. He said, “Future commercialization of the technology will provide a technological breakthrough that will allow for more rapid and efficient analysis of radioactive waste generated during the operation or decommissioning of nuclear facilities.”