Patent ID: 8731128
Filing Date: 2014-05-20
Classification: G21C,Y02E

Abstract:
1. An indexing device installation unit provided at an access tunnel, in a nuclear reactor containment vessel, the access tunnel leading a plurality of guide tubes to a local power range monitor detector provided in a nuclear reactor, the indexing device installation unit comprising: an indexing device of a traversing in-core probe configured to selectively insert the guide tubes to a plurality of areas on the local power range monitor detector, the indexing device being provided in the access tunnel; a base mounted with the indexing device; a holding part configured to hold the base in a suspended state from a ceiling portion of the access tunnel; and a lift mechanism configured to uplift and down the base held by the holding part along with the indexing device in the access tunnel, the lift mechanism forming a predetermined clearance in the access tunnel when uplifting the base, so as to enable a worker to pass through the access tunnel, wherein the holding part has: a sleeve on whose inner surface a female thread is formed; a shaft screwed into the sleeve and having a male thread formed thereon; and a sprocket attached to one end of the sleeve, and one end of the shaft is fixed to the base; and wherein the lift mechanism has a driving source rotating the sprocket in a circumferential direction and, in moving the base up and down, changes a screwing depth of the shaft into the sleeve by rotating the sprocket.