Method for diagnosing three barriers of nuclear power unit

Abstract

The invention provides a nuclear power unit three-barrier diagnosis method. The method comprises the following steps: acquiring operation parameters and state parameters of a nuclear power unit; performing three-barrier diagnosis and nuclear safety function state diagnosis according to the operation parameters and the state parameters to obtain a three-barrier state diagnosis result and a nuclear safety function state diagnosis result; and generating a state diagnosis report according to the three-barrier state diagnosis result and / or the nuclear safety function state diagnosis result, and outputting the state diagnosis report. According to the invention, rapid diagnosis and prediction of the states of the three barriers are realized, the diagnosis efficiency and accuracy are improved, manual intervention is reduced, and powerful support is provided for safe operation of the nuclear power plant.

Description

Technical Field

[0001] This application relates to the field of nuclear power unit safety monitoring technology, and in particular to a method for diagnosing the three barriers of a nuclear power unit. Background Technology

[0002] Diagnosing the status of the three barriers in a nuclear power plant involves evaluating the unit's condition and accident situation. Traditional methods for judging the status of the three barriers in nuclear power plants rely on the skills and experience of operation experts, which are inefficient and prone to errors. Summary of the Invention

[0003] This application provides a method for diagnosing the three barriers of a nuclear power unit, which solves the problem that traditional methods for judging the status of the three barriers in nuclear power plants rely on the technology and experience of operation experts, resulting in low efficiency and a high risk of errors.

[0004] The technical solution adopted by this application to solve its technical problem is: to provide a method for diagnosing the three barriers of a nuclear power unit, wherein the three barriers include fuel cladding, primary loop system and containment, and the method includes:

[0005] Step S1: Obtain the operating parameters and status parameters of the nuclear power unit;

[0006] Step S2: Perform three-barrier diagnosis and nuclear safety functional status diagnosis based on the operating parameters and status parameters to obtain the three-barrier status diagnosis results and nuclear safety functional status diagnosis results;

[0007] Step S3: Generate a status diagnosis report based on the status diagnosis results of the three barriers and / or the status diagnosis results of nuclear safety functions, and output the status diagnosis report.

[0008] In one embodiment, the operating parameters and status parameters include radiation and safety-related operating parameters of the nuclear power unit, nuclear reactor operating status parameters, and the concentration of radioactive materials in the contaminated sump of the plant.

[0009] The radiation and safety-related operating parameters of the nuclear power unit include at least: the highest core outlet temperature, reactor building pressure, containment air radioactivity, pressurizer depressurization line temperature, reactor depressurization tank pressure, leakage from the primary loop to the secondary loop of the steam generator, radioactive material concentration in the steam generator blowdown system, and radioactive material concentration in the condenser.

[0010] The nuclear reactor operating status parameters include at least: control rod position, primary loop boron concentration, shaft seal temperature, primary loop underheating, secondary loop system operating status data, reactor residual heat removal system valves, and steam emission system valve opening.

[0011] In one embodiment, step S2 includes at least:

[0012] If the highest temperature at the core outlet meets the preset no-damage temperature, then the fuel cladding is determined to be undamaged.

[0013] If the highest temperature at the core outlet meets the preset failure temperature, then the fuel cladding is determined to be damaged.

[0014] If the highest temperature at the reactor core outlet meets the preset melting temperature, then the fuel cladding is determined to have melted.

[0015] In one embodiment, step S2 further includes:

[0016] If the reactor building pressure and the containment air radioactivity meet the preset containment breach conditions, then the primary loop breach is determined to be inside the containment.

[0017] If the temperature of the pressurizer depressurization line and the pressure of the reactor depressurization tank meet the preset pressurizer release line rupture conditions, then it is determined that the primary loop rupture is on the pressurizer release line.

[0018] If the concentration of radioactive material in the contaminated pit of the plant meets the preset conditions for a breach outside the containment, then it is determined that the primary loop breach is outside the containment.

[0019] If the concentration of radioactive material in the steam generator's wastewater system meets the preset conditions for the rupture of the steam generator's heat transfer tube, then it is determined that a steam generator heat transfer tube rupture accident has occurred.

[0020] In one embodiment, step S2 further includes:

[0021] If the concentration of radioactive material in the steam generator blowdown system meets the preset non-collectible leakage condition of the penetration component, then it is determined that the penetration component of the containment has a non-collectible leakage.

[0022] If the leakage of the steam generator from the primary circuit to the secondary circuit meets the preset non-collectible leakage condition of the ventilation duct, then it is determined that the ventilation duct of the containment has a non-collectible leakage.

[0023] If the leakage from the primary circuit to the secondary circuit and the steam generator pressure meet the preset non-collectible leakage conditions of the secondary circuit, then it is determined that a non-collectible leakage has occurred in the secondary circuit.

[0024] In one embodiment, step S2 further includes:

[0025] If the position of the control rod is greater than a preset number of steps or the boron concentration in the primary loop meets the preset suspicion condition, then the subcritical state is judged as suspicious.

[0026] In one embodiment, step S2 includes:

[0027] If the underheating of the first loop is undersaturated, then it is determined that the heat dissipation of the first loop system is sufficient.

[0028] If the underheating of the primary loop is a preset saturation or overheating condition, then it is determined that the heat removal of the primary loop system is insufficient.

[0029] If the opening degree of the valves of the reactor waste heat removal system and the valves of the steam emission system meets the preset uncontrollable output condition, then it is determined that the heat output of the primary loop system is uncontrollable.

[0030] In one embodiment, step S2 includes:

[0031] If the shaft seal temperature meets the preset sufficient cooling condition, it is determined that the primary loop system shaft seal cooling is sufficient.

[0032] If the underheating of the primary loop meets the preset weak cooling condition, then it is determined that the cooling of the primary loop system's heat shaft seal is weak.

[0033] In one embodiment, step S2 further includes:

[0034] If the operating status data of the secondary loop system meets the condition that there is no uncollectible leakage data, then the containment integrity is determined to be weak.

[0035] In one embodiment, the status diagnostic report includes at least one of a tabular form and a graphical form.

[0036] Implementing this application has the following beneficial effects: This application provides a method for diagnosing the three-barrier system of a nuclear power unit. The method includes: acquiring the operating parameters and status parameters of the nuclear power unit; performing three-barrier diagnosis and nuclear safety functional status diagnosis based on the operating parameters and status parameters, obtaining three-barrier status diagnosis results and nuclear safety functional status diagnosis results; generating a status diagnosis report based on the three-barrier status diagnosis results and / or nuclear safety functional status diagnosis results, and outputting the status diagnosis report. This application achieves rapid diagnosis and prediction of the three-barrier status, improves diagnostic efficiency and accuracy, reduces manual intervention, and provides strong support for the safe operation of nuclear power plants. Attached Figure Description

[0037] The present application will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0038] Figure 1 This is a flowchart illustrating the diagnostic method for the three barriers of nuclear power units proposed in this application. Detailed Implementation

[0039] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by related similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0040] like Figure 1 As shown, Figure 1 This is a flowchart illustrating the diagnostic method for the three barriers of nuclear power units proposed in this application.

[0041] The technical solution adopted by this invention to solve its technical problem is: constructing a three-barrier diagnostic method for nuclear power units, wherein the three barriers include fuel cladding, primary loop system, and containment, and the method includes:

[0042] Step S1: Obtain the operating parameters and status parameters of the nuclear power unit;

[0043] In this step, it should be noted that the operating parameters and status parameters of the nuclear power unit can be obtained from the nuclear power unit's operating system or its related systems, such as monitoring systems, emergency command systems, or databases, or they can be obtained through manual input.

[0044] Step S2: Perform three-barrier diagnosis and nuclear safety functional status diagnosis based on operating parameters and status parameters, and obtain the three-barrier status diagnosis results and nuclear safety functional status diagnosis results;

[0045] Step S3: Generate a status diagnosis report based on the status diagnosis results of the three barriers and / or the status diagnosis results of nuclear safety functions, and output the status diagnosis report.

[0046] In this step, it should be noted that a status diagnostic report is generated based on the diagnostic results. The report includes detailed information on the fuel cladding status, primary loop system status, containment status, and nuclear safety functional status. The report can be in the form of tables, reports, graphs, etc., for further verification and analysis by operations experts. The output diagnostic report provides nuclear power plant management with effective information on unit status and accident progress.

[0047] This invention utilizes automation technology to achieve rapid diagnosis and prediction of the three-barrier status of nuclear power units, significantly reducing data entry time, improving efficiency, reducing the error rate of manual form filling, and enhancing the accuracy of diagnosis and prediction. The rapidly generated diagnostic and prediction results provide real-time information to nuclear power plant management, supporting emergency decision-making, helping operators promptly identify potential problems and take corrective measures, and ensuring the safe operation of the nuclear power unit. Furthermore, the automatically generated diagnostic reports reduce the manual workload of operators, improving work efficiency, while allowing operation experts to review and modify the automatically generated reports, ensuring their accuracy and reliability. By monitoring and diagnosing the operating status of nuclear power units in real time, this invention can promptly identify and address potential safety issues, thereby improving the overall safety of the nuclear power unit.

[0048] Furthermore, the operating parameters and status parameters include radiation and safety-related operating parameters of the nuclear power unit, operating status parameters of the nuclear reactor, and the concentration of radioactive materials in the contaminated sump of the plant.

[0049] The radiation and safety-related operating parameters of nuclear power units include at least: the highest core outlet temperature, reactor building pressure, containment air radioactivity, pressurizer depressurization line temperature, reactor depressurization tank pressure, leakage from the primary loop to the secondary loop of the steam generator, radioactive material concentration in the steam generator blowdown system, and radioactive material concentration in the condenser.

[0050] Nuclear reactor operating status parameters include at least: control rod position, primary loop boron concentration, shaft seal temperature, primary loop underheating, secondary loop system operating status data, reactor residual heat removal system valves, and steam venting system valve opening.

[0051] Furthermore, step S2 includes at least:

[0052] If the highest temperature at the core outlet meets the preset no-damage temperature, then the fuel cladding is deemed to be undamaged.

[0053] If the highest temperature at the core outlet meets the preset failure temperature, then the fuel cladding is determined to be damaged.

[0054] If the highest temperature at the core outlet meets the preset melting temperature, then the fuel cladding is determined to have melted.

[0055] In one embodiment, fuel cladding condition diagnosis involves obtaining the highest core outlet temperature, which is a key parameter reflecting the fuel cladding condition. This temperature data is obtained through the nuclear power unit's operating system or other relevant systems.

[0056] Assessing Fuel Cladding Condition: Undamaged: If the highest core outlet temperature is lower than the preset undamaged temperature (e.g., 650°C), the fuel cladding is considered undamaged. This indicates the fuel cladding is in good condition and has not suffered any damage. Damaged: If the highest core outlet temperature is higher than the undamaged temperature (650°C) but lower than or equal to the preset damage temperature (e.g., 1100°C), the fuel cladding is considered damaged. This indicates the fuel cladding has been damaged but has not yet reached the point of melting. Melted: If the highest core outlet temperature is higher than the preset melting temperature (e.g., 1100°C), the fuel cladding is considered melted. This indicates the fuel cladding is severely damaged, potentially leading to the release of radioactive materials. See Table 1 for fuel cladding condition diagnosis and assessment criteria.

[0057]

[0058] Table 1: Diagnosis and Judgment Criteria for Fuel Cladding Condition.

[0059] Furthermore, step S2 also includes:

[0060] If the reactor building pressure and containment air radioactivity meet the preset containment breach conditions, then the primary loop breach is determined to be inside the containment.

[0061] If the temperature of the pressurizer depressurization line and the pressure of the reactor depressurization tank meet the preset pressurizer release line rupture conditions, then the primary loop rupture is determined to be on the pressurizer release line.

[0062] If the concentration of radioactive material in the contaminated pit of the plant meets the preset conditions for a breach outside the containment, then the primary circuit breach is determined to be outside the containment.

[0063] If the concentration of radioactive material in the steam generator's wastewater system meets the preset conditions for the rupture of the steam generator's heat transfer tube, then it is determined that a steam generator heat transfer tube rupture accident has occurred.

[0064] In one embodiment, the primary loop breach location is diagnosed to determine if the primary loop breach is inside the containment: if the reactor building pressure is greater than a preset pressure value (e.g., 1.2 bar) and the containment air radioactivity is greater than a preset activity value (e.g., 4 × 10⁻⁶). 6 Bq / m 3 If the primary circuit breach is found inside the containment structure, then the breach is determined to be inside the containment structure.

[0065] In one embodiment, the primary loop rupture location is diagnosed to determine if the primary loop rupture is on the pressurizer release line: if the temperature of the pressurizer depressurization line is greater than a preset temperature value (e.g., 90°C) and the pressure of the reactor depressurization tank is greater than a preset pressure value (e.g., 2 bar), then the primary loop rupture is determined to be on the pressurizer release line.

[0066] In one embodiment, the primary loop breach location is diagnosed to determine if the primary loop breach is outside the containment: if the concentration of radioactive material in the contaminated sump of the plant meets a preset condition (e.g., a high alarm), then the primary loop breach is determined to be outside the containment.

[0067] In one embodiment, the diagnosis of the primary loop rupture location and the diagnosis of a steam generator heat transfer tube rupture accident are performed if the concentration of radioactive material in the steam generator blowdown system is greater than a preset value (e.g., 4 × 10⁻⁶). 7 Bq / m 3 Or, the leakage rate of the steam generator from the primary loop to the secondary loop exceeds a preset value (e.g., 70 L / h, when the reactor nuclear power is greater than 20%), or the leakage rate of the steam generator from the primary loop to the secondary loop exceeds another preset value (e.g., 300 C / s), or the concentration of radioactive material in the condenser exceeds a preset value (e.g., 4 × 10⁻⁶). 7 Bq / m 3 If the condition is met, it is determined that a steam generator heat transfer tube rupture accident has occurred. The primary loop system status diagnosis conditions are shown in Table 2.

[0068]

[0069]

[0070] Table 2. Conditions for diagnosing the status of a primary loop system.

[0071] Furthermore, step S2 also includes:

[0072] If the concentration of radioactive material in the steam generator blowdown system meets the preset non-collectible leakage condition of the penetration, then it is determined that there is a non-collectible leakage in the penetration of the containment.

[0073] If the leakage from the steam generator from the primary circuit to the secondary circuit meets the preset non-collectible leakage condition of the ventilation duct, then it is determined that there is a non-collectible leakage in the ventilation duct of the containment.

[0074] If the leakage from the primary circuit to the secondary circuit and the steam generator pressure meet the preset non-collectible leakage conditions of the secondary circuit, then it is determined that a non-collectible leakage has occurred in the secondary circuit.

[0075] In one embodiment, a non-collectible leak is determined by: the concentration of radioactive material in the steam generator blowdown system meeting a preset non-collectible leak condition (e.g., greater than 4 × 10⁻⁶). 7 Bq / m 3 If the leakage is not collected, it is determined that there is a non-collectible leak in the penetration part of the containment.

[0076] In one embodiment, a non-collectible leak is determined to occur in the containment ventilation duct:

[0077] If the leakage from the steam generator from the primary loop to the secondary loop meets the preset non-collectible leakage condition of the vent pipe (e.g., greater than 70 l / h, when the reactor nuclear power is greater than 20%), then it is determined that there is a non-collectible leakage in the containment vent pipe.

[0078] In one embodiment, the secondary loop system leakage diagnosis determines that a non-collectible leak has occurred in the secondary loop if the leakage rate from the primary loop to the secondary loop and the steam generator pressure meet preset non-collectible leakage conditions in the secondary loop (e.g., the leakage rate from the primary loop to the secondary loop is greater than 300 c / s and the steam generator pressure is less than 2 bar). The containment diagnostic conditions are shown in Table 3.

[0079]

[0080]

[0081] Table 3. Diagnostic criteria for leakage in containment and secondary loop systems.

[0082] Furthermore, step S2 also includes:

[0083] If the value of the intermediate range power measurement channel meets the preset subcritical qualification condition, then the subcritical state is judged to be sufficient.

[0084] If the position of the control rod is greater than the preset number of steps or the boron concentration of the primary loop meets the preset suspicion state condition, then the subcritical state is judged as suspicious.

[0085] If the value of the intermediate range power measurement channel meets the preset subcritical weak condition, then the subcritical state is determined to be weak.

[0086] The preset subcriticality qualification conditions include: the value of the intermediate range power measurement channel is less than the preset value (e.g., 3 × 10⁻⁶ within 20 minutes of reactor shutdown). -5 A, after a 20-minute shutdown, the value is 10. -8 A). Preset suspicious condition conditions include: control rod position greater than a preset number of steps (e.g., greater than 5 steps), indicating that the control rods may not be able to effectively control the nuclear reaction rate; primary loop boron concentration less than the preset suspicious condition condition (e.g., less than 2300 ppm); preset weak subcriticality conditions include: intermediate range power measurement channel value greater than a preset value (e.g., greater than 3 × 10⁻⁶ within 20 minutes of reactor shutdown). -5 A, after a 20-minute shutdown, the value is greater than 10. -8 A).

[0087] In one embodiment, the subcritical safety function diagnosis prioritizes using the value from the intermediate range power measurement channel for judgment. Once the result is obtained, the primary loop boron concentration and control rod position data are no longer processed. If the intermediate range power measurement channel data cannot be obtained, the primary loop boron concentration is used for judgment. If this data also cannot be obtained, the control rod position is used as a final judgment.

[0088] Determine the subcriticality status: Subcriticality is sufficient: If the value of the intermediate range power measurement channel is less than the preset value (e.g., 3 × 10⁻⁶ within 20 minutes of reactor shutdown). -5 A, or stop the stack for 20 minutes and then 10 -8 A) indicates that the subcriticality condition is sufficient. Weak subcriticality: If the value of the intermediate range power measurement channel is greater than the preset value (e.g., 3 × 10⁻⁶ within 20 minutes of reactor shutdown). -5 A, or stop the stack for 20 minutes and then 10 -8 A) If the subcriticality state is weak, it is judged as "suspicious." Subcriticality state is "suspected": Control rod position judgment: If the control rod position is greater than a preset number of steps (e.g., 5 steps), the subcriticality state is judged as "suspicious." This indicates that the control rods may not be effectively controlling the nuclear reaction rate and further investigation is needed. Primary loop boron concentration judgment: If the primary loop boron concentration is less than a preset suspected state condition (e.g., less than 2300 ppm), the subcriticality state is judged as "suspicious." This indicates that the boron concentration in the primary loop may be insufficient to effectively absorb neutrons and control the nuclear reaction rate. The subcriticality state judgment conditions are shown in Table 4.

[0089]

[0090] Table 4 shows the conditions for judging the criticality state.

[0091] Furthermore, step S2 includes:

[0092] If the stabilizing water level and the underheating of the first loop meet the preset conditions for satisfactory first loop water level, then the first loop water level is judged to be satisfactory.

[0093] If the stabilizing water level and the underheating of the primary circuit meet the preset primary circuit water capacity degradation condition, then the primary circuit water capacity status is determined to be degraded.

[0094] If the primary loop underheating meets the preset primary loop water level and core exposure condition, then the primary loop water level status is determined to be core exposure.

[0095] In one embodiment, the preset primary coolant charge conditions include: pressurization level (Lpzr) > 0% and ΔT saturation is undersaturated; or reactor pressure vessel water level (Lvsl) > THL (threshold level) and ΔT saturation is undersaturated. The preset primary coolant charge degradation conditions include: pressurization level (Lpzr) < 0% and ΔT saturation is undersaturated; or reactor pressure vessel water level (Lvsl) < THL and ΔT saturation is undersaturated; or ΔT saturation is saturated. The primary coolant charge state for a bare core includes ΔT saturation being overheated.

[0096] In one embodiment, the primary loop water level is diagnosed to determine if the primary loop water level is satisfactory:

[0097] If the primary coolant circuit is undersaturated and the pressurizer water level is greater than a preset value (e.g., 0%) or the pressure vessel water level is greater than a preset value (e.g., THL), then the primary coolant circuit water level is considered satisfactory. This indicates that the fuel assemblies in the reactor core can be completely covered by water.

[0098] In one embodiment, a primary loop water level diagnosis is performed to determine if the primary loop water level has degraded:

[0099] If the primary circuit is undersaturated and the pressurizer water level is less than the preset value (e.g., 0%) or the pressure vessel water level is less than the preset value (e.g., THL), then the primary circuit water level is degraded.

[0100] If the underheating of the primary loop is saturated, then the water capacity of the primary loop is downgraded.

[0101] In one embodiment, the primary coolant charge level is diagnosed to determine the amount of primary coolant charge and whether the core is exposed.

[0102] If the primary coolant level is underheated, the reactor core is considered exposed due to insufficient primary coolant charge. Table 5 shows the criteria for determining the primary coolant charge state, where ΔTsaturated indicates an overheated state, meaning the water has completely turned into steam and the temperature is above the saturation temperature. ΔTsaturated indicates an undersaturated state, meaning the water temperature is below the saturation temperature and the water has not yet begun to turn into steam. ΔTsaturated indicates a saturated state, meaning the water temperature is equal to the saturation temperature and the water has begun to turn into steam, but has not yet completely turned into steam.

[0103]

[0104] Table 5 shows the criteria for judging the primary water circuit device.

[0105] Furthermore, step S2 also includes:

[0106] If the underheating of the primary loop is undersaturated, then the heat removal of the primary loop system is considered sufficient.

[0107] If the underheating of the primary loop is under the preset saturation or overheating condition, it is determined that the heat removal of the primary loop system is insufficient.

[0108] If the opening degree of the valves in the reactor waste heat removal system and the steam discharge system meets the preset uncontrollable output condition, then the heat output of the primary loop system is determined to be uncontrollable.

[0109] In one embodiment, a primary loop system heat removal diagnosis is performed to determine if the primary loop system has sufficient heat removal capabilities.

[0110] If the primary loop underheating condition is undersaturated, it indicates that the primary loop system has sufficiently dissipated heat. This means that the cooling system is operating effectively, heat is being dissipated in a timely manner, and the temperature of the primary loop system remains within a safe range.

[0111] In one embodiment, a primary loop system heat removal diagnosis is performed to determine if the primary loop system's heat removal is insufficient.

[0112] If the underheating of the primary loop is within the preset saturation or overheating conditions, it indicates insufficient heat removal from the primary loop system. This suggests a potential problem with the cooling system, and insufficient heat removal may cause the temperature of the primary loop system to rise, requiring further inspection and handling.

[0113] In one embodiment, the primary loop system heat exhaust diagnostic determines that the primary loop system heat exhaust is uncontrollable: if the opening degrees of the valves in the reactor residual heat removal system and the steam exhaust system meet the preset uncontrollable exhaust conditions (e.g., the system is connected), then the primary loop system heat exhaust is determined to be uncontrollable. This indicates that the heat exhaust system may have failed, and immediate measures are needed to restore the system to normal operation. The primary loop system heat exhaust determination conditions are shown in Table 6.

[0114]

[0115] Table 6. Criteria for judging heat output from the primary loop system.

[0116] Furthermore, step S2 includes:

[0117] If the shaft seal temperature meets the preset sufficient cooling condition, it is determined that the primary loop system shaft seal cooling is sufficient.

[0118] If the underheating of the primary loop meets the preset weak cooling condition, then the cooling of the primary loop system's heat shaft seal is determined to be weak.

[0119] In one embodiment, the shaft seal cooling status is diagnosed to determine if the shaft seal cooling is sufficient:

[0120] If the shaft seal temperature meets the preset sufficient cooling condition (e.g., shaft seal temperature less than 60℃), then the primary loop system shaft seal cooling is considered sufficient. This indicates that the shaft seal cooling system is operating normally and can effectively maintain the shaft seal temperature within a safe range.

[0121] Determining Weak Shaft Seal Cooling: If the underheating of the primary loop meets the preset weak cooling condition (e.g., shaft seal temperature greater than 100℃), then the primary loop system's shaft seal cooling is determined to be weak. This indicates a potential problem with the shaft seal cooling system, resulting in insufficient cooling and requiring further inspection and handling. The shaft seal cooling status judgment conditions are as follows:

[0122] As shown in Table 7.

[0123]

[0124]

[0125] Table 7. Criteria for judging the cooling status of shaft seals.

[0126] Furthermore, step S2 also includes:

[0127] If the operating status data of the secondary loop system meets the condition that there is no uncollectible leakage, then the containment integrity is determined to be weak.

[0128] In one embodiment, containment integrity diagnosis determines that the containment integrity is weak:

[0129] If the operating status data of the secondary loop system meets the condition of having no uncollectible leaks, then the containment integrity is judged to be weak. This indicates that there may be a leak in the secondary loop system, but the leakage amount has not yet reached the level of being uncollectible, and further inspection and handling are required. The containment integrity diagnostic conditions are shown in Table 8.

[0130] The remaining status of containment integrity requires analysis of the specific accident process, and the judgment should be made by operation experts based on experience according to the acquired accident information.

[0131]

[0132] Table 8. Diagnostic criteria for containment integrity.

[0133] Furthermore, the status diagnostic report should include at least one of the following formats: tabular or graphical.

[0134] This application provides a method for diagnosing the three-barrier function of a nuclear power unit. The method includes: acquiring the operating parameters and status parameters of the nuclear power unit; performing three-barrier function diagnosis and nuclear safety functional status diagnosis based on the operating parameters and status parameters, obtaining three-barrier function status diagnosis results and nuclear safety functional status diagnosis results; generating a status diagnosis report based on the three-barrier function status diagnosis results and / or nuclear safety functional status diagnosis results, and outputting the status diagnosis report. This application achieves rapid diagnosis and prediction of the three-barrier function status, improves diagnostic efficiency and accuracy, reduces manual intervention, and provides strong support for the safe operation of nuclear power plants.

[0135] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that for those skilled in the art, free combinations of the above technical features and various modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for diagnosing the three barriers of a nuclear power unit, wherein the three barriers include fuel cladding, primary loop system, and containment, characterized in that, The method includes: Step S1: Obtain the operating parameters and status parameters of the nuclear power unit; Step S2: Perform three-barrier diagnosis and nuclear safety functional status diagnosis based on the operating parameters and status parameters to obtain the three-barrier status diagnosis results and nuclear safety functional status diagnosis results; Step S3: Generate a status diagnosis report based on the status diagnosis results of the three barriers and / or the status diagnosis results of nuclear safety functions, and output the status diagnosis report.

2. The method for diagnosing the three barriers of a nuclear power unit according to claim 1, characterized in that, The operating parameters and status parameters include radiation and safety-related operating parameters of nuclear power units, operating status parameters of nuclear reactors, and the concentration of radioactive materials in contaminated sump pits of the plant. The radiation and safety-related operating parameters of the nuclear power unit include at least: the highest core outlet temperature, reactor building pressure, containment air radioactivity, pressurizer depressurization line temperature, reactor depressurization tank pressure, leakage from the primary loop to the secondary loop of the steam generator, radioactive material concentration in the steam generator blowdown system, and radioactive material concentration in the condenser. The nuclear reactor operating status parameters include at least: control rod position, primary loop boron concentration, shaft seal temperature, primary loop underheating, secondary loop system operating status data, reactor residual heat removal system valves, steam emission system valve opening, intermediate range power measurement channel values, and primary loop underheating.

3. The method for diagnosing the three barriers of a nuclear power unit according to claim 2, characterized in that, Step S2 includes at least the following: If the highest temperature at the core outlet meets the preset no-damage temperature, then the fuel cladding is determined to be undamaged. If the highest temperature at the core outlet meets the preset failure temperature, then the fuel cladding is determined to be damaged. If the highest temperature at the reactor core outlet meets the preset melting temperature, then the fuel cladding is determined to have melted.

4. The method for diagnosing the three barriers of a nuclear power unit according to claim 2, characterized in that, Step S2 further includes: If the reactor building pressure and the containment air radioactivity meet the preset containment breach conditions, then the primary loop breach is determined to be inside the containment. If the temperature of the pressurizer depressurization line and the pressure of the reactor depressurization tank meet the preset pressurizer release line rupture conditions, then it is determined that the primary loop rupture is on the pressurizer release line. If the concentration of radioactive material in the contaminated pit of the plant meets the preset conditions for a breach outside the containment, then it is determined that the primary loop breach is outside the containment. If the concentration of radioactive material in the steam generator's wastewater system meets the preset conditions for the rupture of the steam generator's heat transfer tube, then it is determined that a steam generator heat transfer tube rupture accident has occurred.

5. The method for diagnosing the three barriers of a nuclear power unit according to claim 2, characterized in that, Step S2 further includes: If the concentration of radioactive material in the steam generator blowdown system meets the preset non-collectible leakage condition of the penetration component, then it is determined that the penetration component of the containment has a non-collectible leakage. If the leakage of the steam generator from the primary circuit to the secondary circuit meets the preset non-collectible leakage condition of the ventilation duct, then it is determined that the ventilation duct of the containment has a non-collectible leakage. If the leakage from the primary circuit to the secondary circuit and the steam generator pressure meet the preset non-collectible leakage conditions of the secondary circuit, then it is determined that a non-collectible leakage has occurred in the secondary circuit.

6. The method for diagnosing the three barriers of a nuclear power unit according to claim 2, characterized in that, Step S2 further includes: If the value of the intermediate range power measurement channel meets the preset subcritical qualification condition, then the subcritical state is judged to be sufficient. If the position of the control rod is greater than the preset number of steps or the boron concentration of the primary loop meets the preset suspicion state condition, then the subcritical state is judged as suspicious. If the value of the intermediate range power measurement channel meets the preset subcritical weak condition, then the subcritical state is determined to be weak.

7. The method for diagnosing the three barriers of a nuclear power unit according to claim 2, characterized in that, The step S2 comprises: If the stabilizing water level and the underheating of the first loop meet the preset conditions for satisfactory first loop water level, then the first loop water level is judged to be satisfactory. If the stabilizing water level and the underheating of the primary circuit meet the preset primary circuit water capacity degradation condition, then the primary circuit water capacity status is determined to be degraded. If the primary loop underheating meets the preset primary loop water level and core exposure condition, then the primary loop water level status is determined to be core exposure.

8. The method for diagnosing the three barriers of a nuclear power unit according to claim 2, characterized in that, The step S2 comprises: If the shaft seal temperature meets the preset sufficient cooling condition, it is determined that the primary loop system shaft seal cooling is sufficient. If the underheating of the primary loop meets the preset weak cooling condition, then it is determined that the cooling of the primary loop system's heat shaft seal is weak.

9. The method for diagnosing the three barriers of a nuclear power unit according to claim 2, characterized in that, Step S2 further includes: If the operating status data of the secondary loop system meets the condition that there is no uncollectible leakage data, then the containment integrity is determined to be weak.

10. The method for diagnosing the three barriers of a nuclear power unit according to claim 1, characterized in that, The status diagnostic report shall include at least one of the following formats: tabular or graphical.

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