How does the PRC-function work?
The Product Radiation Compensation (PRC) feature provides reliable, accurate level measurement through an independent activity measurement and integral compensation. Here, two separate detector systems are used, which simultaneously measure the level and the radiation from the product. Even under difficult process conditions, a high measurement accuracy can thus be ensured.
In case the source must be exchanged …
Radiometric sources decay by time. So the signal to noise ratio to the natural background radiation is going worse. If you already have installed radiometric measurements and are faced with the decision to replace the meanwhile weak sources, a PRC system can initially prevent the replacement of a source. Because with the PRC measurement, the background effect, which interferes more and more in the case of a weak source, is simply subtracted.
Successes with PRC level measurement
The PRC measurement has already been applied successfully several times. For example, in an uranium processing plant in which the level of uranium-suspension is measured in several vessels. The dose rate originating from the product radiation is roughly around 80 µSv/h. Similarly, in the production of polypropylene, the PRC measurement could provide a solution. The radiation intensity, initiated by the radioactivity in the measured product may result in dose rates of 0,5 to 3 µSv/h, which is approximately in the range of the usual designed source radiation at the detector.
Berthold's measuring solution with PRC
If NORM is present, wouldn’t it be good to know how strong the product radiation is at any given moment? This is possible with a second detector! It only has to be shifted around the vessel so that the radiation from the source does not reach the "compensation detector". The information from this "compensation detector" must then be simply transferred to the level detector and will be processed there. This option provides our level measurement system LB 480 SENSseries.Thus, a level gauge is realized, that is independent of any product radiation.
Graphic representation of level measurement with natural radioactivity
The trend illustrates how the measured value of a level measurement is falsified if the radiation in the product continuously increases over time.
Detector versions with PRC
The PRC-measurement is available as a level gauge in the following SENSseries detector versions:
- CrystalSENS (point detector)
- UniSENS (rod detector)
- SuperSENS (point detector with highest sensitivity)
In PRC measurements, a point detector is preferably used, because it is easier and better to shield. Moreover the point detector is located at a significantly larger distance to the radioactive product, as it is mounted at the 100% level position.