METHOD AND DEVICE FOR MEASURING LEVEL IN RADIOACTIVE WASTE LIQUID STORING TANK

PURPOSE:To measure a boundary level between supernatant liquid and a deposition layer as well as the level of waste liquid without direct contact with the waste liquid, by moving a radiation detector relatively to the direction of the height of a storing tank, and by finding the level from a change in the strength of radiation in the direction of the height of the tank. CONSTITUTION:A radiation detecting apparatus 12 is set adjacently to a storing tank 10, and a lift 15 whereon a shielding vessel 14 is mounted is driven upward at a prescribed speed. A radiation falling into a slender hole 16 of the shielding vessel 14 is detected by a radiation detector 13, subjected to signal processing in a radiation signal processing circuit 18, and compared with a value set beforehand in a discrimination circuit 19. The level of the incident radiation lowers remarkably with the elevation of the radiation detector 13, and when an input measurement signal falls below the set value, the position of the detector 13 is called by a driving control circuit 17 and is indicated in an indicator 21 as the level of waste liquid or a boundary between a deposition layer and supernatant liquid.