On-line monitoring and analysis of reactor vessel integrity
First Claim
1. A method of real-time on-line monitoring and analysis of nuclear reactor pressure vessel integrity in a unit in which reactor coolant is circulated along the inner wall of the pressure vessel, said method comprising the steps of:
- generating signals representative of the temperature of the reactor coolant at selected critical points along said inner wall of the pressure vessel even under stagnant flow conditions on a real-time basis;
generating signals representative of the pressure of the reactor coolant on a real-time on-line basis; and
generating on a real-time on-line basis, as a function of changes in the temperature and pressure signals, a visual representation of a margin to non-ductile failure of the vessel at selected critical points for all flaw depths through the vessel wall.
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Accused Products
Abstract
A real time analysis of nuclear reactor vessel integrity is preformed by monitoring reactor coolant temperature and pressure and fast neutron fluence, and generating therefrom a visual comparison of the reference nil-ductility transition temperature, RTndt, required for flaw initiation and the actual RTndt through the entire depth of the vessel wall at selected critical locations. When flaw initiation is indicated at any depth, the RTndt required for flaw propagation arrest is also generated and displayed. A display can also be generated to provide guidance for optimum performance during heatup and cooldown. Thermocouples located at the reactor core inlet are used in conjunction with the resistance temperature detectors, RTDs, conventionally provided in the cold leg conduits to generate a more accurate measurement of the coolant temperature at the critical locations in the vessel. Under stagnant flow conditions a correlation is applied to the RTD readings to provide the best estimate of coolant temperature at the critical locations.
33 Citations
29 Claims
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1. A method of real-time on-line monitoring and analysis of nuclear reactor pressure vessel integrity in a unit in which reactor coolant is circulated along the inner wall of the pressure vessel, said method comprising the steps of:
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generating signals representative of the temperature of the reactor coolant at selected critical points along said inner wall of the pressure vessel even under stagnant flow conditions on a real-time basis; generating signals representative of the pressure of the reactor coolant on a real-time on-line basis; and generating on a real-time on-line basis, as a function of changes in the temperature and pressure signals, a visual representation of a margin to non-ductile failure of the vessel at selected critical points for all flaw depths through the vessel wall. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for on-line monitoring and real-time analysis of nuclear reactor pressure vessel integrity in a reactor unit in which reactor coolant is circulated along the inner wall of the pressure vessel, said apparatus comprising:
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means for measuring on a real-time on-line basis the temperature of the reactor coolant along the inner wall of the pressure vessel from measurements taken at a point spaced from the inner wall of the vessel even under stagnant flow conditions; means for measuring on a real-time on-line basis the pressure of the reactor coolant; digital computer means for periodically sampling said reactor coolant temperature and pressure measurements and for generating on a real-time on-line basis, as a function of changes over time in the measured temperature and pressure, vessel condition signals representative of the proximity to non ductile failure of the pressure vessel wall at selected critical locations for all flaw depths through the pressure vessel wall; a visual display device; and means for applying said vessel condition signals generated by the digital computer to the visual display device to generate a real-time on-line visual representation of the proximity of the pressure vessel wall to non-ductile failure at the critical locations for all flaw depths. - View Dependent Claims (10, 11, 12, 13)
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14. A method of on-line monitoring and analysis of nuclear reactor pressure vessel integrity in a unit in which reactor coolant is circulated along the inner wall of the pressure vessel, said method comprising the steps of:
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generating on an on-line basis, temperature signals representative of the temperature of the reactor coolant circulating along the inner wall of the pressure vessel; generating on an on-line basis, a pressure signal representative of the reactor coolant pressure; generating a signal representative of fast neutron fluence to which the reactor pressure vessel has been subjected; generating as a function of said fluence signal a visual representation of the actual real time reference nil-ductility transition temperature (RTndt) across the entire pressure vessel wall thickness at a preselected critical location in said wall; generating as a function of transients in said reactor coolant temperature and pressure signals, a visual representation of the real time required RTndt, across the entire pressure vessel wall thickness at said selected critical location, said required RTndt being the RTndt that would be required in the pressure vessel wall for flaw initiation to occur as a result of stresses set-up by said transients; and superimposing said visual representations of the real-time actual and required RTndt'"'"'s for flaw initiation across the entire pressure vessel wall thickness for the selected critical location to generate a visual representation of the difference in value between the actual and required RTndt presented as an RTndt margin. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. A method of on-line monitoring and analysis of the integrity of a vessel in which the inner wall thereof is contacted with a fluid which is subject to varying temperature and pressure conditions, the method comprising the steps of;
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generating on an on-line basis signals representative of the temperature of said fluid adjacent the inner wall of the vessel; generating on an on-line basis signals representative of the pressure of said fluid; generating signals representative of the actual reference nil-ductility transition temperature (RTndt) across the entire vessel wall thickness at a preselected critical location in said vessel wall; generating as a function of transients in said fluid temperature and pressure signals, signals representative of the real time required RTndt for flaw initiation across the entire vessel wall thickness at said selected critical location, said required RTndt for flaw initiation being the RTndt that would be required in the vessel wall for flaw initiation to occur as a result of stresses set up by said transients; and comparing said actual RTndt signals with the required RTndt singals for flaw initiation to generate a representation of the difference in value between the actual and required RTndt signals. - View Dependent Claims (23, 24, 25, 26)
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27. In combination:
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a nuclear reactor having a reactor core housed in a pressure vessel with reactor coolant circulating along the inner surface of the pressure vessel walls and through the reactor core; means for on-line measurement of the reactor coolant temperature and for generating temperature signals therefrom; means for on-line measurement of the reactor coolant pressure and for generating a pressure signal therefrom; digital computer means for periodically sampling said reactor coolant temperature and pressure signals and for generating as a function of said on-line temperature and pressure signals, signals representative for selected locations in the vessel of real-time reference nil-ductility transition temperatures (RTndt) required for flaw initiation across the vessel wall as a result of stresses induced by changes in said temperature and pressure signals and for generating signals representative of the actual RTndt across the vessel wall at each selected location; and display means for generating a visual display comparing the real-time RTndt signals required for flaw initiation with the actual RTndt signals for each selected location. - View Dependent Claims (28)
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29. Apparatus for on-line monitoring and analysis of the integrity of a vessel in which the inner wall thereof is contacted by a fluid which is subjected to varying temperature and pressure conditions, said apparatus comprising:
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means for measuring on an on-line basis the temperature of the fluid contacting the vessel wall; means for measuring on an on-line basis the pressure of the fluid; and digital computer means for periodically sampling the fluid temperature and pressure measurements and for generating on an on-line basis as a function of said on-line temperature and pressure measurements, signals representative, for at least one selected location along the inner wall of said vessel, of real-time reference nil-ductility transition temperatures (RTndt) required for flaw initiation at all depths across the vessel wall as a result of stresses induced by changes in said temperature and pressure measurements, and for generating signals representative of the actual RTndt across the vessel wall at said selected location; and means for comparing the actual RTndt signal with the required RTndt signal for flaw initiation to generate a representation of the difference in value between the actual and required RTndt signals.
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Specification