[en] Purpose: To enable inspection for the external appearance of fuel rods in the inside of fuel assemblies. Constitution: An external appearance inspection device main body vertically guided swingeably along the axial direction of a fuel assembly comprises a probe moving mechanism and a fiber scope probe. The device also has a fiber scope transmission part, an industrial television transmitter, an optical source, a VTR and a television receiver. The probe is inserted into the gap between fuel rods, and can be moved within a horizontal plane by the probe driving mechanism. The probe is moved vertically together with the external appearance inspection device main body by vertically moving the wire rope by a winch. The probe is also constituted such that it can be withdrawn from between the fuel rods and moved in the direction perpendicular to the drawing. (Yoshihara, H.)