Patent ID: 9543046
Date: 2017-01-10
CPC Classifications: G21C,Y02E

Claim:
1. A detection apparatus that can determine whether spent nuclear fuel rods are missing or have been replaced with dummy spent nuclear fuel rods or have been replaced with fresh spent nuclear fuel rods, wherein the spent nuclear fuel rods are part of a spent nuclear fuel array located in a spent nuclear fuel storage pool, the spent nuclear fuel array having the spent nuclear fuel rods arranged in a quadrant symmetric pattern with guide tubes adjacent and between the spent nuclear fuel rods, comprising: a detection apparatus insertion fixture positioned in said spent nuclear fuel storage pool and adapted to contact the spent nuclear fuel array, said detection apparatus insertion fixture including a slider assembly with insertion tubes adapted to be inserted into the guide tubes in the spent nuclear fuel array, said insertion tubes moveable in the guide tubes of the spent nuclear fuel array by said slider assembly, a first detector and a second detector contained within the insertion tubes, wherein said first detector and said second detector are neutron detectors or gamma detectors and wherein said first detector and said second detector detect radiation responses, wherein the insertion tubes are between the spent nuclear fuel rods that are arranged in a quadrant symmetric pattern, wherein the insertion tubes containing said first detector and said second detector are inserted into the guide tubes adjacent the spent nuclear fuel rods and move through the guide tubes in the spent nuclear fuel array wherein said first detector and said second detector are in predetermined positions in the quadrant symmetric pattern; a measuring and analyzing device, said measuring and analyzing device connected to said first detector and said second detector wherein said first detector and said second detector are located in predetermined positions in the quadrant symmetric pattern for measuring said radiation responses of said first detector and said second detector at the predetermined positions in the quadrant symmetric pattern simultaneously at said predetermined positions in the quadrant symmetric pattern and processing said radiation responses and producing a signature; and wherein said measuring and analyzing device uses said signature for determining whether some spent nuclear fuel rods within the spent nuclear fuel array in the spent nuclear fuel storage pool are missing or have been replaced with dummy spent nuclear fuel rods or have been replaced with fresh spent nuclear fuel rods using said signature by determining whether said signature has been perturbed from the quadrant symmetric pattern.