| 摘要 |
PROBLEM TO BE SOLVED: To provide a structure wherein a detector is easily replaced while no impurity is accumulated, by simplifying a structure wherein a water level of a reactor is detected with ultra sonic wave and electro-magnetic wave. SOLUTION: Water and steam are present in a housing tube 4 which penetrates a reactor vessel upper lid 3, and a guide tube 2 of single pipe structure is assigned in it, and a detector 1 provided inside the guide tube 2, while connected to an external measurement device with a signal line 5. With ultra sonic wave emitted from the detector 1, based on difference in reflection coefficient of ultra sonic wave between on the steam and on the water (the reflection coefficient for steam is larger than that for water), a liquid level is detected. With the detector 1 vertically moved with a driving mechanism, liquid-surface measurement is performed continuously. There is no narrow part in the housing tube 4 because the guide tube 2 is a single tube, so no impurity is accumulated and replacement of the detector 1 is easier. |
