How does the PRC-function work?
The Product Radiation Compensation (PRC) feature provides reliable, accurate level measurement through an independent NORM radiation measurement and integral compensation. Two separate detectors are used, once measuring only NORM, the other NORM and the gamma from the Berthold source which is affected by level. The counts per second from the first detector are used to cancel out the effect of NORM on the second detector. With this Product Radiation Compensation, even under difficult process conditions a high measurement accuracy can be ensured.
In case the source must be exchanged …
Radiometric sources decay over time, which means the signal to noise ratio of the natural background radiation to process indication becomes worse with time. As Berthold’s PRC compensates for background fluctuations, instead of replacing an aged source, you can delay the source replacement by adding PRC which will decrease noise, and increase accuracy and reliability.
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 product radiation at a dose rate of 0.5 µSv/h can be up 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
To set up a PRC system, the nuclear source is placed across the vessel from a level detector, while a second detector of the same size is added perpendicular to the beam path coming from the nuclear source so that it is only seeing NORM. The information from this "compensation detector" is relayed to the level detector and is used to remove the impact of NORM from the level calculations and output. This function allows Berthold’s LB 480 SENSseries Level measurement system to provide a level output independent of any product radiation.