| 摘要 |
PURPOSE:To prevent the occurrence of vibration, by providing a pair of key grooves which respectively have such a tapered surface as to allow slip between said key groove and plural key grooves, which are circumferentially formed in the inner surface of the lower part off a nozzle and the outer surface of a sleeve in a manner to be positioned facing each other. CONSTITUTION:A through-hole is bored in a lower end plate 11 of a reactor pressure vessel, a nozzle 11b is inserted thereinto, and is coupled to a sleeve 12a of a motor case 12. 3 or more key grooves 13, axially extended, are circumferentially formed in the inner surface of the lower end of the sleeve 11b, and key grooves 14, having a tapered surface, are formed in a position, allowing the key grooves to be respectively positioned facing the key grooves 13, in the outer surface of the end of the sleeve 12a. This, even if an axis is displaced due to a pressure and thermal deformation, prevents an increase in contact surface of the key, and enables prevention of production of vibration through relief of stress.
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