Patent Number: 
Section: claims

1. An apparatus for detecting a position of a control rod, the apparatus comprising:a control rod driving shaft having an outer circumferential surface on which position information is marked;a mirror configured to reflect the position information; anda detector configured to detect a position of the control rod driving shaft from the position information reflected by the mirror, when the control rod driving shaft moves vertically,wherein the mirror is disposed to surround the control rod driving shaft along the outer circumferential surface of the control rod driving shaft and is formed of quartz and has a ring shape,the position information is marked as a number or a bar code in order to determine an absolute position of the control rod driving shaft,the detector comprises:an optical system comprising a lens configured to receive an image of the position information reflected from the mirror;an optical fiber connected to the optical system and configured to transmit the image,the optical fiber comprises an inner fiber surrounded and protected by a high-temperature gel, an inner stainless tube, an aluminum tube, and an outer stainless tube, sequentially. 2. The apparatus of claim 1, wherein the detector comprises:a storage unit configured to store the image transmitted from the optical fiber; anda display unit configured to display the image stored in the storage unit to the outside of a nuclear reactor. 3. The apparatus of claim 1, wherein the mirror has a hollow truncated cone shape with a through-hole through which the control rod driving shaft passes. 4. The apparatus of claim 1, wherein a plurality of grooves for vertically moving the control rod driving shaft are formed in the outer circumferential surface of the control rod driving shaft, and the position information is formed between the grooves. 5. The apparatus of claim 2, further comprising an optical connector configured to transmit the image to the outside of the nuclear reactor.