| 摘要 |
PURPOSE:To detect securely positions of a floating fuel assembly between core gaps and a control rod in a disconnection failure state by adding plural transducers which face a reflecting plate to a holder provided under a transducer driving mechanism. CONSTITUTION:When the fuel assembly 5'' charged in a reactor core is monitored, the reflecting plate 19 and transducers 11 are provided opposite to each other across the core gap between the reactor core 4 and an upper mechanism (not shown in a figure). In this case, a couple of swivel arms 10'' and 10'' are stored in a holder 10' provided under the transducer driving mechanism (not shown in the figure) so that the arms are opened and closed in opposite directions, the transducers 11 and 11 are provided in the arms 10'' and 10'' so that they move forth and back as specified, and another transducer 11 is provided at the internal bottom part of the holder 10' in level with the arms 10''. Consequently, the transducers 11, 11, and 11 are scanned with phase difference and a floating fuel assembly 5'', etc. in the core gap 18 is detected. |
