Arrangement and procedure for the level indication utilizing internal radiation sources

This invention has to do with an arrangement and procedure for the liquid level indication in pressurized water reactors and steam generators in nuclear power plants. The level indication is not dependent of reactor power and is thermally compensated. No additional impacts on the pressure vessels are necessary. Technology-inherent internal radiation sources (reactor core, activated coolant) are used and according to the law of radiation absorption in connection with calibration during normal reactor operation the coolant level within the pressure vessels can be derived from the detector signals