Patent Number: 
Section: claims

1. A system to determine a position of a control rod within a nuclear power plant, the control rod being movable by predetermined increments along a range of motion, the control rod being associated with a plurality of detection coils that are spaced apart at predetermined intervals along the range of motion such that a spacing of the predetermined intervals is greater than a spacing of the predetermined increments, the system comprising:a data acquisition unit configured to communicate with each detection coil and to detect output signals from the plurality of the detection coils as the control rod is moved by predetermined increments along the range of motion, the output signals having fluctuations corresponding to each incremental movement of the drive rod; anda processing unit in communication with the data acquisition unit, the processing unit being configured to derive the axial position of the control rod relative to each predetermined increment based on the fluctuations corresponding to each incremental movement. 2. The system of claim 1, wherein at least one of the predetermined increments is positioned within one of the detection coils. 3. The system of claim 2, wherein a fluctuation corresponding to the at least one of the predetermined increments is used to derive the axial position of the control rod relative to said one of the detection coils. 4. A method of determining a position of a control rod within a nuclear power plant, the control rod being movable by predetermined increments along a range of motion, the control rod being associated with a plurality of detection coils that are spaced apart at predetermined intervals along the range of motion such that a spacing of the predetermined intervals is greater than a spacing of the predetermined increments, the method comprising:detecting output signals from the plurality of the detection coils as the control rod is moved by predetermined increments along the range of motion, the output signals having fluctuations corresponding to each incremental movement of the drive rod; andprocessing the detected output signals to derive the axial position of the control rod relative to each predetermined increment based on the fluctuations corresponding to each incremental movement. 5. The method of claim 4, wherein at least one of the predetermined increments is positioned within one of the detection coils. 6. The method of claim 5, wherein a fluctuation corresponding to the at least one of the predetermined increments is used to derive the axial position of the control rod relative to said one of the detection coils.