Patent ID: 8811566

Claim:
A guide thimble plug of a nuclear fuel assembly, the guide thimble plug comprising: a main body having an internal threaded hole located through the main body, the main body for coupling to a bottom nozzle in a lower end by the internal threaded hole and directly coupling to a shock absorption tube and a guide thimble in an upper portion thereof; an upper insert part located in an upper end of the main body and having an external thread located on a circumferential outer surface thereof for coupling to the shock absorption tube; a thermal deformation prevention part located on the main body below the upper insert part, the thermal deformation prevention part being recessed inward from an outer surface of the main body, wherein when the main body is coupled to the guide thimble, a gap is defined between the thermal deformation prevention part and the guide thimble; and a protruding part located between the upper insert part and the thermal deformation prevention part and having an upper surface in the upper insert part side, the upper surface being perpendicular to the outer surface of the main body so as to support a lower end of the shock absorption tube, a lower surface in the thermal deformation prevention part side, and an outer surface on a circumferential outer surface thereof, the outer surface having a diameter greater than a diameter of the thermal deformation prevention part, for being forcibly fitted into the guide thimble, wherein a width of the thermal deformation prevention part is two or more times greater than a width of the protruding part.