| 摘要 |
PURPOSE:To detect the flow velocity and temperature sufficiently with a higher sound detection sensitivity, by heightening the residual magnetic flux density of a permanent magnet to enhance the bias magnetic field in a compound sensor for fuel assembly of a sodium cooling type nuclear reactor. CONSTITUTION:A compound sensor 25 is provided on a flow guide for a fuel assembly of a nuclear reactor. Pure iron cores 22 and 22A are provided in a container of the sensor 25 in contact with a permanent magnet 40, magnetrostrictive vibrators 41 and 41A and a magnetrostrictive vibrator 41. A ceramic bobbin 24 is wound with an primary exciting coil 21 and secondary exciting coils 22 and 22A. Then, the residual magnetic flux density of the permanent magnet 40 is heightened to give magnetostrictive vibrators 41 and 41A a high bias magnetic field. The magnetostrictive vibrator 41A is separated from the permanent magnet 40 with the one side thereof 41A made a free end so as to keep sound energy from propagating to the permanent magnet 40. Thus, a greater electromechanical connection factor of the magnetostrictive can raise the sound detection sensitivity thereby enabling sufficient detection of the temperature and flow velocity alike in an eddy current type temperature/flowmeter. |
