Title:
METHOD OF MEASURING IDLE GAP AND APPARATUS FOR CARRYING OUT THE METHOD
Document Type and Number:
Japanese Patent JPS5393863
Kind Code:
A
Abstract:
Measurement of the play between a drive nut of non-magnetic material and a drive spindle is described for a control rod drive mechanism, in which the nut is free to move axially in a sleeve which prevents it from rotating, but is limited in its axial movement by a stop surface. A special drive mechanism is fitted to the spindle and is used for rotating it until the nut meets the stop surface; an emitter forming part of an indicator for magnetic field intensity is then placed outside the sleeve and close to a permanent magnet fixed to the nut; the spindle is then rotated in the opposite direction until the indicator indicates a change in the field intensity, which is evidence that the magnet and therefore the nut has now moved. The angle of rotation of the spindle which has occurred in this reverse direction is then measured and from this the play is calculated. Used in control rod mechanisms, where the nut typically is made of graphite, the wear is so high that about 20% of the mechanisms need replacement each year. The method enables the amount of play resulting from the wear to be determined without dismantling any part of the control rod drive mechanism.
Inventors:
INGUBAARU ASUTE
Application Number:
JP533678A
Publication Date:
August 17, 1978
Filing Date:
January 23, 1978
Export Citation:
Assignee:
ASEA ATOM AB
International Classes:
G01B7/00; G01B7/14; G21C7/14; (IPC1-7): G01D5/12; G21C7/14