| 摘要 |
PURPOSE:To shorten a preheating time to a large extent and to reduce the thermal shock to a transducer, by transmitting the heat of a high temp. liquid to the transducer through a heating medium and a highly heat-conductive liquid. CONSTITUTION:Prior to the separation operation of a control rod, a holding tube 13 is pierced through a shield plug 14 to be fallen into a nuclear reactor storing vessel and temporarily stopped in such a state that a heat-conductive body 35 is immersed in a cooling material but the bottom surface 13a of the lower end part of the holding tube 13 is not immersed. Because the cooling material 3 is held to high temp., the hermetically sealed container 37 of the heating medium 35 is quickly heated and the heat of said medium 35 is gradually conducted to a heat conductive rod 36 through a metal small sphere 38 being a heat resistant element and reaches a transducer 8 relatively rapidly through the bottom part 13a and heating liquid medium 34 to preheat the same to the vicinity of the temp. of the cooling material 3. Therefore, thermal shock is not generated in the transducer 8 at all and a preheating time is shortened to a large extent. When the transducer 8 almost reaches the temp. of the cooling material 3, the holding tube 13 is further fallen to monitor the confirmation of the separation of the control rod.
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