Patent Number: 055552790
Section: claims

1. A computer-based power oscillation monitoring system for detection and indication of thermal-hydraulic stability margin in a nuclear reactor having a core including a plurality of fuel assemblies, said system comprising: a) a plurality of neutron flux detectors in the nuclear reactor core contiguous to the fuel assemblies, said plurality of flux detectors being distributed throughout the reactor core, said plurality of flux detectors providing a like plurality of output signals, each output signal being indicative of the neutron flux of the portion of the core adjacent the corresponding flux detector;  b) a computer-based detector processing system utilizing:  c) a corrective signal means for improving reactor stability margin when said simulated decay ratio signal reaches a predetermined level.  a) a plurality of neutron flux detectors in the nuclear reactor core contiguous to the fuel assemblies, said plurality of flux detectors being distributed throughout the reactor core, said plurality of flux detectors providing a like plurality of output signals, each output signal being indicative of the neutron flux of the portion of the core adjacent the corresponding flux detector, said plurality of output signals being organized into a plurality of flux detector output signal groups;  b) a frequency filter for removing select frequency components of said flux detector output signals that are of a frequency in excess of a characteristic frequency range of a thermal-hydraulic instability;  c) a computer-based detector processing system utilizing:  d) a corrective signal means for improving reactor stability margin when said simulated decay ratio signal reaches a predetermined level.  a) a plurality of neutron flux detectors in the nuclear reactor core contiguous to the fuel assemblies, said flux detectors being approximately equally distributed throughout the reactor core, said plurality of flux detectors providing a like plurality of output signals, each output signal being indicative of the power density of the portion of the core adjacent the corresponding flux detector, said plurality of output signals organized into one or more flux detector output signal groups;  b) a computer-based detector processing system utilizing:  c) a corrective signal means for improving reactor stability margin when said simulated decay ratio signal reaches a predetermined level.  a) a plurality of neutron flux detectors in the nuclear reactor core contiguous to the fuel assemblies, said flux detectors being distributed throughout the reactor core, said plurality of flux detectors providing a like plurality of output signals, each said output signal being indicative of the neutron flux of the portion of the core adjacent the corresponding flux detector, said plurality of output signals being organized into one or more flux detector output signal groups;  b) a frequency filter for removing select frequency components of said flux detector output signals that are of a frequency in excess 0.7 Hz;  c) a computer-based detector processing system utilizing:  d) a suppression signal means for issuing an oscillation suppression signal when said simulated decay ratio signal in any group reaches a predetermined level.  a) providing a plurality of neutron flux detectors in the nuclear reactor core contiguous to the fuel assemblies, said plurality of flux detectors being distributed throughout the reactor core, said plurality of flux detectors providing a like plurality of output signals, each output signal being indicative of the power density of the portion of the core adjacent the corresponding flux detector;  b) processing said output signal of each flux detector utilizing a computer-based detector processing system by the steps of:  c) providing a corrective signal means for improving reactor stability margin when said simulated decay ratio signal reaches a predetermined level.  a) providing a plurality of neutron flux detectors in the nuclear reactor core contiguous to the fuel assemblies, said plurality of flux detectors being distributed throughout the reactor core, said plurality of flux detectors providing a like plurality of output signals, each output signal being indicative of the neutron flux of the portion of the core adjacent the corresponding flux detector;  b) providing a frequency filter for removing select frequency components of said flux detector output signals that are of a frequency in excess of a characteristic frequency range of a thermal-hydraulic instability;  c) processing said output signal of each flux detector utilizing a computer-based detector processing system by the steps of:  d) providing a corrective signal means for improving reactor stability margin when said simulated decay ratio signal reaches a predetermined level.  a) providing a plurality of neutron flux detectors in the nuclear reactor core contiguous to the fuel assemblies, said flux detectors being distributed throughout the reactor core, said plurality of flux detectors providing a like plurality of output signals, each output signal being indicative of the power density of the portion of the core adjacent the corresponding flux detector, said plurality of output signals being organized into a one or more flux detector output signal groups;  b) processing said output signal of each flux detector utilizing a computer-based detector signal processing system by the steps of:  c) providing a corrective signal means for improving reactor stability margin when said simulated decay ratio signal reaches a predetermined level.  a) providing a plurality of neutron flux detectors in the nuclear reactor core contiguous to the fuel assemblies, said flux detectors being distributed throughout the reactor core, said plurality of flux detectors providing a like plurality of output signals, each output signal being indicative of the power density of the portion of the core adjacent the corresponding flux detector, said plurality of output signals being organized into one or more of flux detector output signal groups;  b) filtering for removal of select frequency components of said flux detector output signals that are of a frequency in excess 0.7 Hz;  c) processing said output signal of each flux detector utilizing a computer-based detector signal processing system by the steps of:  d) a suppression signal means for issuing an oscillation suppression signal when said simulated decay ratio signal in any group reaches a predetermined level. 2. The computer-based oscillation detection system of claim 1, wherein said system includes a frequency filter for removing select frequency components of said flux detector output signals that are of a frequency in excess of a characteristic frequency range of a thermal-hydraulic instability. 3. The filter of claim 2, wherein the filter provides for removal of select components of said flux detector output signal that are of a frequency greater than approximately 0.7 Hz. 4. The computer-based oscillation detection system of claim 1, wherein the neutron flux detectors are local power range monitors. 5. The computer-based oscillation detection system of claim 1, wherein the simulated decay ratio algorithm divides the plurality of flux detector output signals into a plurality of groups, each group corresponding to a plurality of flux detectors spread throughout the core, and each group being processed individually and simultaneously to yield the simulated decay ratio signal. 6. The computer-based oscillation detection system of claim 1, wherein the simulated decay ratio algorithm includes a spike rejection means to minimize the effect of unexpected, single, large deviations in the periodicity signals of the flux detectors. 7. The computer-based oscillation detection system of claim 1, wherein the simulated decay ratio algorithm includes a smoothing function means. 8. A computer-based power oscillation monitoring system for detection and indication of thermal-hydraulic stability margin in a nuclear reactor having a core including a plurality of fuel assemblies, said system comprising: 9. A computer-based power oscillation monitoring system for detection and indication of thermal-hydraulic stability margin in a nuclear reactor having a core including a plurality of fuel assemblies, said system comprising: 10. The computer-based oscillation detection system of claim 9, wherein said system includes a frequency filter for removing frequency components of said flux detector output signals that are of a frequency in excess of a characteristic frequency range of a thermal-hydraulic instability. 11. The filter of claim 10, wherein the filter provides for removal of select components of said flux detector output signal that are of a frequency greater than approximately 0.7 Hz. 12. The computer-based oscillation detection system of claim 9, wherein the neutron flux detectors are local power range monitors. 13. The computer-based oscillation detection system of claim 9, wherein said time block is in the range of approximately 1 to 60 seconds. 14. The computer-based oscillation detection system of claim 9, wherein said time block is dynamically established. 15. The computer-based oscillation detection system of claim 9, wherein the simulated decay ratio algorithm includes a spike rejection means to generate an effective successive confirmation count signal based on the block successive confirmation count signal to minimize the effect of unexpected, single, large deviations in the block successive confirmation count signal. 16. The computer-based oscillation detection system of claim 9, wherein the simulated decay ratio algorithm includes a smoothing function means to process the effective confirmation count signal to generate a nominal successive confirmation count signal that minimizes changes in the block successive confirmation count resulting from statistical variations from one time block to another. 17. The computer-based oscillation detection system of claim 9, wherein the simulated decay ratio algorithm includes a spike rejection means to generate an effective successive confirmation count signal based on the block successive confirmation count signal to minimize the effect of unexpected, single, large deviations in the block successive confirmation count signal, and a smoothing function means to process the effective successive confirmation count signal to generate a nominal successive confirmation count signal that minimizes changes in the block successive confirmation count resulting from statistical variations from one time block to another. 18. A computer-based power oscillation monitoring system for detection and indication of thermal-hydraulic instabilities in a nuclear reactor having a core including a plurality of fuel assemblies, said system comprising: 19. A computer-based method for detecting, monitoring and indicating thermal-hydraulic stability margin in a nuclear reactor having a core including a plurality of fuel assemblies, said system comprising: 20. The computer-based method of claim 19, wherein said method includes providing a frequency filter for removing frequency components of said flux detector output signals that are of a frequency in excess of a characteristic frequency range of a thermal-hydraulic instability. 21. The computer-based method of claim 20, wherein the step of providing the filter provides for removal of select components of said flux detector output signal that are of a frequency greater than approximately 0.7 Hz. 22. The computer-based method of claim 19, wherein the step of providing the neutron flux detectors includes providing local power range monitors spatially distributed throughout the core. 23. The computer-based method of claim 19, wherein the step of processing the output signal employing the simulated decay ratio algorithm includes dividing the plurality of flux detector output signals into one or more groups, each group corresponding to a plurality of flux detectors spread throughout the core, and each group being processed individually and simultaneously to yield the simulated decay ratio signal. 24. The computer-based method of claim 19, wherein the step of processing the output signal employing the simulated decay ratio algorithm includes employing a spike rejection means to minimize the effect of unexpected, single, large deviations in the periodicity signals of the flux detectors. 25. The computer-based method of claim 19, wherein the step of processing the output signal employing the simulated decay ratio algorithm includes employing a smoothing function means. 26. A computer-based method for detecting, monitoring and indicating thermal-hydraulic stability margin in a nuclear reactor having a core including a plurality of fuel assemblies, said system comprising: 27. A computer-based method for detecting, monitoring, and indicating thermal-hydraulic stability margin in a nuclear reactor having a core including a plurality of fuel assemblies, said system comprising: 28. The computer-based method of claim 27, including frequency filtering for removal of select frequency components of said flux detector output signals that are of a frequency in excess of a characteristic frequency range of a thermal-hydraulic instability. 29. The filter of claim 28, wherein the step of filtering includes removing select components of said flux detector output signal that are of a frequency greater than approximately 0.7 Hz. 30. The computer-based method of claim 27, wherein the neutron flux detectors are local power range monitors. 31. The computer-based method of claim 27, wherein each said time block is in the range of approximately 1 to 60 seconds. 32. The computer-based method of claim 11, wherein said time block is dynamically established. 33. The computer-based method of claim 27, including providing a spike rejection means to generate an effective successive confirmation count signal based on the block successive confirmation count signal to minimize the effect of unexpected, single, large deviations in the block successive confirmation count signal. 34. The computer-based method of claim 27, including providing a smoothing function means to process the effective confirmation count signal to generate a nominal successive confirmation count signal that minimizes changes in the block successive confirmation count resulting from statistical variations from one time block to another. 35. The computer-based method of claim 27, including providing a spike rejection means to generate an effective successive confirmation count signal based on the block successive confirmation count signal to minimize the effect of unexpected, single, large deviations in the block successive confirmation count signal, and a smoothing function means to process the effective successive confirmation count signal to generate a nominal successive confirmation count signal that minimizes changes in the block successive confirmation count resulting from statistical variations from one time block to another. 36. A computer-based method for detecting, monitoring and indicating thermal-hydraulic stability margin in a nuclear reactor having a core including a plurality of fuel assemblies, said system comprising: