Test method for lower limit of leakage of No.1 seal of nuclear reactor main pump

Abstract

The present application relates to a method for testing the lower limit of the leakage of the No. 1 seal of a nuclear reactor main pump, comprising: S100 selecting a preset lower limit value, adjusting the temperature in the test chamber to a first temperature, so that the leakage of the No. 1 seal corresponding to the first temperature is the preset lower limit value; S200 rotating the pump shaft simulation component and the dynamic ring, and monitoring the leakage of the No. 1 seal; S300 continuously cooling the test chamber; S400 judging whether the leakage of the No. 1 seal is stable at the current value; S500 if the leakage of the No. 1 seal is stable at the current value, proceeding to step S600; if the leakage of the No. 1 seal is not stable at the current value, and the overall growth rate is less than the upper limit growth rate, increasing the cooling level of the test chamber, and returning to step S400 for re-judgment; S600 shutting down the test system, and taking the current value of the No. 1 seal leakage that is stable in step S500 as the lower limit of the No. 1 seal leakage. The above-mentioned test method can measure the lower limit of the leakage of the No. 1 seal of the main pump to obtain its true lower limit value.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear power, in particular to a method for testing the lower limit of leakage of a No. 1 seal of a nuclear reactor main pump. Background Art

[0002] The reactor main pump (also known as the coolant pump) is a critical piece of equipment in a nuclear power plant. Its primary function is to ensure the continuous circulation of coolant within the primary circuit. During operation, to prevent coolant leakage into the pump shaft area, three seals are installed on the main pump shaft: seal number one, seal number two, and seal number three, arranged from bottom to top. Seal number one is the primary component and is a controlled-leakage seal that relies on a liquid film suspension. Seal number one consists of a stationary ring and a rotating ring, which are mounted on the pump shaft and arranged axially. The rotating ring is fixedly connected to the pump shaft and rotates synchronously with the shaft. A gap exists between the stationary ring and the outer circumference of the pump shaft, allowing the stationary ring to move axially, thereby changing the gap size. During operation, injection water at a pressure higher than the reactor primary coolant system (RCP) enters the pump. A portion of this injection water flows downward into the RCP system, preventing primary coolant from entering the pump shaft and seal area. A portion of the injected water flows through the gap between the moving and stationary rings of the No. 1 seal and flows upward through the gap between the stationary ring and the pump shaft. Afterwards, some of this injected water flows through the No. 2 seal and some flows into the leakage line of the No. 1 seal. By measuring the flow rate in the leakage line of the No. 1 seal, the leakage rate of the No. 1 seal can be determined.

[0003] Typically, the leakage of the No. 1 seal is a critical parameter. If the value is too low, it can cause abnormal wear on the dynamic and static rings of the No. 1 seal, necessitating the pump shutdown for maintenance. Therefore, the main pump manufacturer pre-determines a lower limit for the leakage of the No. 1 seal. When using the main pump, nuclear power plants must monitor the leakage of the No. 1 seal in real time to prevent it from falling below the lower limit and being missed. However, based on the main pump's operating conditions, staff discovered that the manufacturer's lower limit for the leakage of the No. 1 seal was overly conservative. In reality, while ensuring that the dynamic and static rings do not experience abnormal wear, the leakage of the No. 1 seal can be reduced to a much lower level. Therefore, a test method is urgently needed to measure the lower limit of the No. 1 seal's leakage. Summary of the Invention

[0004] Based on this, the present invention proposes a method for testing the lower limit of leakage of the No. 1 seal of the main pump of a nuclear reactor, which can measure the lower limit of leakage of the No. 1 seal of the main pump to obtain its true lower limit value.

[0005] A method for testing the lower limit of leakage of the No. 1 seal of a nuclear reactor main pump includes the following steps:

[0006] S100 selects a preset lower limit value, adjusts the temperature in the test chamber to a first temperature, and makes the leakage of seal No. 1 corresponding to the first temperature reach the preset lower limit value;

[0007] S200 rotates the pump shaft simulation and the dynamic ring and monitors the leakage of the No. 1 seal;

[0008] S300 continuously cools the test cavity;

[0009] S400 determines whether the leakage of seal No. 1 is stable at the current value;

[0010] If the leakage of seal No. 1 is stable at the current value in step S500, proceed to step S600; if the leakage of seal No. 1 is not stable at the current value and is increasing at a rate less than the upper limit, increase the cooling level of the test chamber and return to step S400 for another determination.

[0011] In step S600 , the test system is shut down, and the current value of the leakage of the No. 1 seal maintained stably in step S500 is used as the lower limit of the leakage of the No. 1 seal.

[0012] In one embodiment, step S100 includes:

[0013] S110: raising the temperature of the test chamber to a second temperature;

[0014] S130: lowering the temperature of the test chamber from the second temperature to the first temperature;

[0015] The temperature difference between the second temperature and the first temperature is greater than 50 degrees, and the leakage of the No. 1 seal is monitored during step S100.

[0016] In one embodiment, step S100 further includes step S120 located between step S110 and step S130:

[0017] The test chamber is maintained at the second temperature for a preset time period.

[0018] In one embodiment, step S130 includes:

[0019] S131 starts the refrigerator to cool the test chamber;

[0020] S132 opens the low-temperature water inflow channel to allow the low-temperature water to flow through the test chamber;

[0021] S133 determines the temperature of the test chamber. If the temperature of the test chamber is higher than the first temperature, the low-temperature water inflow channel remains open; if the temperature of the test chamber is equal to the first temperature, the low-temperature water inflow channel is closed.

[0022] In one embodiment, the method of increasing the cooling level of the test chamber in step S500 is:

[0023] The low-temperature water inflow channel is opened to allow the low-temperature water to flow through the test cavity.

[0024] In one embodiment, the method of increasing the cooling level of the test chamber in step S500 is:

[0025] The rotational speed of the pump shaft dummy is reduced.

[0026] In one embodiment, the step S700 is further included after the step S600:

[0027] The wear of the dynamic ring and the static ring is detected. If there is no abnormal wear, the lower limit of the leakage of the No. 1 seal determined in step S600 is valid; if there is abnormal wear, the lower limit of the leakage of the No. 1 seal determined in step S600 is invalid.

[0028] In one embodiment, the step S010 is further included before the step S100:

[0029] Install seal No. 1 in the test cavity and check the sealing of the test cavity. If the sealing requirements are met, proceed to the next step. If the sealing requirements are not met, suspend the test.

[0030] In one embodiment, step S020 is further included between step S010 and step S100:

[0031] Injection water is sent into the test chamber to increase the pressure of the test chamber to the No. 1 sealing working pressure.

[0032] In one embodiment, the method for obtaining the preset lower limit value is:

[0033] The parameters of the No. 1 seal are obtained, a No. 1 seal geometric model is established based on the parameters, and a No. 1 seal leakage lower limit simulation calculation is performed based on the No. 1 seal geometric model using simulation software.

[0034] The above-mentioned method for testing the lower limit of the leakage of the No. 1 seal of the main pump of a nuclear reactor first selects a preset lower limit value in step S100, and adjusts the temperature in the test chamber to a first temperature so that the corresponding No. 1 seal leakage at this time is the preset lower limit value. Then, in step S200, the pump shaft simulation component drives the dynamic ring to rotate (simulating the rotation of the pump shaft and the dynamic ring under the working state), and the leakage of the No. 1 seal is detected, and the dynamic test under the working state is entered. Since the injected water generates heat due to friction when flowing through the gap between the static ring and the dynamic ring, and after the dynamic ring starts to rotate, the heat generated by the friction of the liquid film increases, the temperature in the test chamber tends to rise. Therefore, in step S300, the test chamber is continuously cooled in the hope of offsetting the temperature increase caused by the friction heat generated by the liquid film, thereby keeping the leakage at a relatively stable low level. After the cooling process, in step S400, it is judged whether the leakage of the No. 1 seal is stable at the current value. In step S500, if the leakage rate has not stabilized at its current value and is increasing, the current cooling level is insufficient to offset the heat generated by fluid film friction, the test chamber temperature is still rising, and the leakage rate cannot be maintained at its current low level. Furthermore, if the leakage rate is increasing at a rate less than the upper limit, this indicates that there has been no significant leakage surge, thus confirming that abnormal wear of the dynamic and static rings is not occurring. (Typically, if the gap between the dynamic and static rings is too small, the leakage rate will fall below the lower limit, causing abnormal wear between the dynamic and static rings, and subsequently, a surge in the leakage rate and the test chamber temperature.) In this case, the cooling level of the test chamber needs to be increased to achieve a balance with the frictional heat generation. Step S400 is then repeated to determine whether the leakage rate has stabilized at its current value. If the leakage rate has not stabilized at its current value and is increasing at a rate less than the upper limit, the cooling level is increased and the process returns to step S400 for further determination until the leakage rate stabilizes at its current value, proceeding to step S600. At this point, the leakage rate has been able to maintain its current low level, preserving the stability of the dynamic and static rings. The test system is shut down, and the current value of the leakage of the No. 1 seal maintained stably in step S500 is the lower limit of the leakage of the No. 1 seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the structure of the connection between the No. 1 seal and the pump shaft;

[0036] Figure 2 Schematic diagram of the structure of the test system in one embodiment of the present application (simplified version);

[0037] Figure 3 This is a flow chart of a method for testing the lower limit of leakage of the No. 1 seal of a nuclear reactor main pump in one embodiment of the present application;

[0038] Figure 4 for Figure 3Flowchart of step S100;

[0039] Figure 5 for Figure 3 Flowchart of step S130;

[0040] Figure 6 for Figure 3 Flowchart after step S600;

[0041] Figure 7 for Figure 3 Flowchart before step S100.

[0042] Reference numerals:

[0043] No. 1 seal 110, dynamic ring 111, static ring 112, pump shaft 120, seal housing 130, gap 140, slit 150, No. 2 seal 160, No. 3 seal 170;

[0044] Test bench 200, test chamber 210, pump shaft simulation part 220, driving part 230;

[0045] The injected water flows into pipeline 310 and No. 1 sealed leakage pipeline 320. DETAILED DESCRIPTION

[0046] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0047] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0049] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0050] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0051] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0052] Figure 1 This is a schematic diagram of the structure of the connection between the No. 1 seal and the pump shaft; Figure 2 Schematic diagram of the structure of the test system in one embodiment of the present application (simplified version).

[0053] See Figure 1 and Figure 2The reactor main pump (i.e., coolant pump) is one of the important equipment in a nuclear power plant. Its main function is to realize the continuous circulation of coolant in a single loop. During the operation of the main pump, in order to prevent the coolant from leaking into the pump shaft 120 area, three seals are set on the pump shaft 120 of the main pump, namely, seal No. 1 110, seal No. 2 160, and seal No. 3 170 arranged in sequence from bottom to top. Among them, seal No. 1 110 is the main component and is a controlled leakage seal that relies on liquid film suspension. Seal No. 1 110 includes a dynamic ring 111 and a static ring 112 that are sleeved on the pump shaft 120 and arranged at intervals along the axial direction of the pump shaft 120. Among them, the dynamic ring 111 is fixedly connected to the pump shaft 120 and can rotate synchronously with the pump shaft 120. The static ring 112 is fixedly connected to the sealing outer cover 130. There is a gap 150 between the static ring 112 and the outer circumference of the pump shaft 120. The static ring 112 can move along the axial direction of the pump shaft 120 to change the size of the gap 140 between the dynamic ring 111 and the static ring 112. When the main pump is working, injection water with a pressure higher than the RCP (reactor main coolant system) enters the pump, and part of the injection water flows downward into the RCP system to inhibit the first-circuit coolant from entering the pump shaft 120 and the seal area. Part of the injection water flows into the gap 140 between the dynamic ring 111 and the static ring 112 of the No. 1 seal 110, and flows upward through the gap 150 between the static ring 112 and the pump shaft 120 ( Figure 1 The direction indicated by the arrow is the flow direction of this injected water. Subsequently, part of this injected water flows through the second seal 160, and part flows into the first seal leakage pipeline 320. By detecting the flow rate of the first seal leakage pipeline 320, the leakage amount of the first seal can be obtained.

[0054] Generally, the leakage of the No. 1 seal is a relatively important parameter. If the value is too low, it will cause abnormal wear of the dynamic ring 111 and the static ring 112 of the No. 1 seal 110, and the pump must be stopped for maintenance. Therefore, the main pump manufacturer will pre-set the lower limit of the leakage of the No. 1 seal. When using the main pump, the nuclear power plant must monitor the leakage of the No. 1 seal in real time to avoid it falling below the lower limit and not being discovered in time. However, based on the operation of the main pump, the staff found that the lower limit of the leakage of the No. 1 seal given by the manufacturer (here, defined as the rated lower limit) was too conservative. In fact, under the premise of ensuring that the dynamic ring 111 and the static ring 112 do not suffer abnormal wear, the leakage of the No. 1 seal can reach a lower level.

[0055] Based on this, the present invention proposes a method for testing the lower limit of leakage of the No. 1 seal of the main pump of a nuclear reactor, which can measure the lower limit of leakage of the No. 1 seal of the main pump to obtain its true lower limit value.

[0056] Figure 3 This is a flow chart of a method for testing the lower limit of leakage of the No. 1 seal of a nuclear reactor main pump in one embodiment of the present application.

[0057] See Figures 1 to 3 A method for testing the lower limit of leakage of the No. 1 seal of a nuclear reactor main pump provided by an embodiment of the present invention comprises the following steps:

[0058] S100 selects a preset lower limit value and adjusts the temperature in the test chamber 210 to a first temperature so that the leakage of the No. 1 seal corresponding to the first temperature is the preset lower limit value;

[0059] S200 rotates the pump shaft simulation component 220 and the dynamic ring 111, and monitors the leakage of the No. 1 seal;

[0060] S300 continuously cools the test chamber 210;

[0061] S400 determines whether the leakage of seal No. 1 is stable at the current value;

[0062] If the leakage of seal No. 1 is stable at the current value in step S500, proceed to step S600. If the leakage of seal No. 1 is not stable at the current value and is increasing at a rate less than the upper limit, increase the cooling level of test chamber 210 and return to step S400 for another determination.

[0063] In step S600 , the test system is shut down, and the current value of the leakage of the No. 1 seal maintained stably in step S500 is used as the lower limit of the leakage of the No. 1 seal.

[0064] Specifically, the test method provided by the present invention is carried out on a test bench 200, and a test chamber 210 is provided in the test bench 200 for providing a test environment. The No. 1 seal 110, the No. 2 seal 160, and the No. 3 seal 170 are installed in the test chamber 210. The pump shaft simulation part 220 is installed in the test chamber 210 for simulating the pump shaft 120. The driving part 230 can drive the pump shaft simulation part 220 and the dynamic ring 111 to rotate to simulate the rotation of the pump shaft 120 and the dynamic ring 111 under the working state. The driving part 230 can be a motor. Generally, temperature, pressure and the inclination angle (cone angle) of the bottom slope of the static ring 112 will affect the leakage of the No. 1 seal. When the pressure and the cone angle remain unchanged, the leakage of the No. 1 seal will decrease as the temperature decreases.

[0065] The above-described method for testing the lower limit of the No. 1 seal leakage of a nuclear reactor main pump begins with, in step S100, selecting a preset lower limit and adjusting the temperature within the test chamber 210 to a first temperature such that the corresponding No. 1 seal leakage at this point is at the preset lower limit. Then, in step S200, the pump shaft simulator 220 rotates the dynamic ring 111 (simulating the rotation of the pump shaft 120 and dynamic ring 111 under operating conditions), and the No. 1 seal leakage is measured, thus entering the dynamic operating test. Since the injected water generates frictional heat when flowing through the gap 140 between the stationary ring 112 and the dynamic ring 111, and the heat generated by the fluid film friction increases after the dynamic ring 111 begins to rotate, the temperature within the test chamber 210 tends to rise. Therefore, in step S300, the test chamber 210 is continuously cooled to offset the temperature increase caused by the fluid film frictional heat generation, thereby maintaining the leakage at a relatively stable low level (i.e., lower than the leakage under normal operating conditions). After the cooling process, in step S400, it is determined whether the leakage of the current No. 1 seal is stable at the current value. In step S500, according to the judgment result, if the leakage is not stable at the current value and is in a growing state, it means that the current cooling level cannot offset the heat generated by the friction of the liquid film, the temperature of the test chamber 210 is still rising, and the leakage cannot be maintained at the current low level; at the same time, the overall leakage increases at a growth rate less than the upper limit growth rate, indicating that there is no leakage surge, which means that there is no abnormal wear between the current dynamic ring 111 and the static ring 112 (usually, if the gap 140 between the dynamic ring 111 and the static ring 112 is too small, the leakage will be lower than the lower limit, and abnormal wear will occur between the dynamic ring 111 and the static ring 112, and then the leakage and the temperature of the test chamber 210 will surge). At this time, it is necessary to increase the cooling level of the test chamber 210 to achieve a balance with the friction heat generation. Then, the process returns to step S400 and repeatedly determines whether the leakage has stabilized at its current value. If the leakage has not stabilized at its current value and is increasing at a rate less than the upper limit, the cooling level is increased and the process returns to step S400 for further determination until the leakage stabilizes at its current value, whereupon the process proceeds to step S600. At this point, the leakage has been essentially stabilized at its current low level, ensuring that no abnormal wear occurs on the dynamic ring 111 or the static ring 112. The test system is shut down, and the current value of the No. 1 seal leakage that has been stabilized in step S500 is the No. 1 seal leakage lower limit.

[0066] It should be noted that the leakage rate mentioned in this application can be stabilized at a certain value, not strictly maintained at that value. A fluctuation of 10L / h above or below that value is considered stable at that value. For example, a leakage rate fluctuation between 100L / h and 120L / h is considered stable at 110L / h. In addition, the temperature surge mentioned in this application refers to a temperature increase of greater than 15°C / min, and the leakage surge refers to a leakage increase of greater than 300L / min.

[0067] As mentioned above, when the pressure and cone angle remain unchanged, the leakage of seal No. 1 will decrease as the temperature decreases. In step S300, the present invention adopts a method of lowering the temperature to reduce the leakage of seal No. 1, so that the leakage of seal No. 1 reaches a lower value. If the result of step S400 is negative, it means that the current cooling level is not enough to offset the heat generated by liquid film friction. Although the size of the gap 140 has temporarily reached a smaller value, the leakage has also reached a lower value accordingly, but both cannot be maintained for a long time and will soon increase as the temperature rises. Therefore, although the current leakage is very low, the current leakage is not the actual lower limit. When the leakage is too low, abnormal wear of the dynamic ring 111 and the static ring 112 may occur. However, if the result of step S400 is negative, and the overall leakage is increasing at a growth rate less than the upper limit growth rate, it means that the leakage has not surged, and further indicates that although the current leakage is low, it will not cause abnormal wear. However, if the judgment result of step S400 is negative, and the overall leakage volume is increasing at a rate greater than the upper limit growth rate (i.e., the growth rate when the aforementioned growth rate is 300L / min), that is, a surge occurs, then it means that the current leakage volume may have fallen below the actual lower limit value, which may have caused abnormal wear. In this case, it is necessary to abandon the test, reset the preset lower limit value and the parameters of the test system, and retest. When the cooling level is continuously increased and the test returns to step S400 for re-judgment, the current cooling level can offset the heat generated by the friction of the liquid film, so that the leakage volume of seal No. 1 is basically stable at a value (denoted as a). a is the minimum leakage volume that can be stably maintained under the current conditions, that is, the lower limit of leakage volume.

[0068] In some embodiments, the method for obtaining the preset lower limit value is:

[0069] The parameters of the No. 1 seal 110 are obtained, a geometric model of the No. 1 seal is established based on the parameters, and a simulation calculation of the lower limit of the No. 1 seal leakage is performed based on the geometric model of the No. 1 seal using simulation software.

[0070] Specifically, a special calculation tool for the main pump mechanical seal is formed by encapsulating the FEA software, and a multi-physics field analysis and calculation of fluid-solid thermal coupling is implemented for the No. 1 seal 110, and simulation calculations are performed after the model is calibrated. When the geometric model of the No. 1 seal is established based on the parameters of the No. 1 seal 110, the parameters used include the inner diameter, outer diameter, height, inflection point radius, cone angle, etc. of the No. 1 seal 110. In a specific embodiment, when establishing the theoretical performance calculation model of the main pump mechanical seal, a 2D axisymmetric method is adopted, wherein the static ring 112 is a double-cone angle design, and the dynamic ring 111 and the static ring 112 are made of Si3N4. In this embodiment, according to the simulation results, the preset lower limit value is 120L / h. When the first temperature is 30°C, the corresponding leakage amount is 120L / h. It should be noted that at the first temperature, the leakage amount only needs to be able to reach near 120L / h, for example, between 112L / h and 128. In other embodiments, the numerical range of the preset lower limit value is not limited. Depending on the reactor type, main pump model and specific parameters of the No. 1 seal of the nuclear reactor, the preset lower limit value may have other ranges.

[0071] In addition, the preset lower limit value can also be selected based on the rated lower limit value given by the manufacturer of the main pump and its No. 1 seal, that is, the preset lower limit value can be less than the rated lower limit value. In actual application, multiple preset lower limit values ​​can be selected based on the rated lower limit value and tested in sequence.

[0072] Figure 4 for Figure 3 Flowchart of step S100 in FIG.

[0073] See Figures 2 to 4 In some embodiments, step S100 includes:

[0074] S110: raising the temperature of the test chamber 210 to a second temperature;

[0075] S130: lowering the temperature of the test chamber 210 from the second temperature to the first temperature;

[0076] The temperature difference between the second temperature and the first temperature is greater than 50 degrees, and the leakage of the No. 1 seal is monitored during step S100.

[0077] Specifically, the first temperature is 30° C., and the second temperature is 95° C. The test chamber 210 is heated by a heater to reach the second temperature.

[0078] As previously mentioned, as the temperature decreases, the leakage of seal No. 1 decreases accordingly. If the temperature is set directly to the first temperature, the corresponding leakage of seal No. 1 will be higher than the leakage of seal No. 1 corresponding to the first temperature when the temperature is lowered from the second temperature. Therefore, by first raising the temperature of test chamber 210 and then lowering it, the leakage of seal No. 1 can be kept at a lower level, making it easier to reach the preset lower limit. (This is determined by the inherent characteristics of seal No. 1. As the temperature changes, the material of stationary ring 112 deforms, causing the cone angle to change. When the temperature drops rapidly, the cone angle becomes smaller, and therefore the leakage is reduced.)

[0079] Furthermore, in step S130, the temperature of test chamber 210 is lowered from the second temperature to the first temperature at a cooling rate b, where b is greater than 30°C / h. This means that the temperature of test chamber 210 is rapidly lowered from the second temperature to the first temperature. This significantly reduces leakage, lowering the leakage of seal No. 1 at the first temperature, making it easier to reach the preset lower limit.

[0080] See Figures 2 to 4 In some embodiments, step S100 further includes step S120 located between step S110 and step S130:

[0081] The test chamber 210 is maintained at the second temperature for a preset period of time.

[0082] Specifically, the preset time period may be more than half an hour. When the second temperature is maintained for a period of time before cooling, the initial leakage amount at the beginning of cooling can be kept at a more stable level.

[0083] Figure 5 for Figure 3 Flowchart of step S130 in FIG.

[0084] See Figure 2 、 Figure 3 and Figure 5 In some embodiments, step S130 includes:

[0085] S131 turns on the refrigerator to cool the test chamber 210;

[0086] S132 opens the low-temperature water inflow channel to allow the low-temperature water to flow through the test chamber 210;

[0087] S133 determines the temperature of the test chamber 210. If the temperature of the test chamber 210 is higher than the first temperature, the low-temperature water inflow channel remains open; if the temperature of the test chamber 210 is equal to the first temperature, the low-temperature water inflow channel is closed.

[0088] Specifically, after test chamber 210 has been maintained at the second temperature for a predetermined period of time, the refrigerator is turned on to cool test chamber 210. Simultaneously, a low-temperature water inlet channel is opened, allowing low-temperature water to flow into test chamber 210, absorb heat, and then be discharged from test chamber 210. This rapidly cools test chamber 210, lowering the leakage level of seal No. 1 corresponding to the first temperature to a lower level, making it easier to reach the predetermined lower limit. Specifically, low-temperature water at 10°C can be used to flow into test chamber 210.

[0089] When the temperature of the test chamber 210 drops to the first temperature, the driver 230 is turned on to drive the pump shaft simulation 220 to rotate at a speed of 1500 rpm. At this time, the low-temperature water inflow channel is closed, and only the refrigerator is used for cooling.

[0090] If the conclusion determined in step S400 is that the leakage of seal No. 1 can be stabilized at the current value, then the current cooling level provided by the refrigerator alone can meet the demand. If it cannot be stabilized at the current value, the cooling level needs to be increased and the process returns to step S400 for further determination.

[0091] See Figure 2 and Figure 3 In some embodiments, the method for improving the cooling level of the test chamber 210 in step S500 is:

[0092] The low-temperature water inflow channel is opened to allow the low-temperature water to flow through the test chamber 210 .

[0093] Specifically, activate driver 230 to check whether the leakage from seal number one is increasing, but not dramatically. If so, the maximum cooling level provided by the refrigerator (which can adjust its cooling level based on cooling demand) is insufficient to offset the frictional heat generated by the liquid film after rotating ring 111 begins rotating. Therefore, in addition to cooling the chamber with the refrigerator, the low-temperature water inlet channel can be re-activated, allowing low-temperature water to flow through test chamber 210 for auxiliary cooling and to offset frictional heat generation.

[0094] Since the temperature of the low-temperature water entering the channel is fixed, the cooling capacity it can provide is limited. Therefore, if the current cooling level still cannot meet the demand after the low-temperature water flow is opened, additional measures are needed to further improve the cooling level.

[0095] See Figure 2 and Figure 3 In some embodiments, the method for improving the cooling level of the test chamber 210 in step S500 is:

[0096] The rotational speed of the pump shaft dummy 220 is reduced.

[0097] It is understandable that when the rotational speed of the pump shaft simulator 220 is reduced, the rotational speed of the dynamic ring 111 is also reduced, and the frictional heat generated by the liquid film between the dynamic ring 111 and the static ring 112 will be reduced, which can indirectly reduce the temperature of the test chamber 210. Therefore, when the cooling demand cannot be met by the refrigerator and low-temperature water alone, the rotational speed of the pump shaft simulator 220 can be reduced on this basis. Of course, in other embodiments, the cooling level can be further improved by reducing the temperature of the low-temperature water in the low-temperature water flow channel. In some embodiments, the rotational speed of the pump shaft simulator 220 can also be reduced only on the basis of the refrigerator cooling, without opening the low-temperature water flow channel.

[0098] Furthermore, if the cooling level is improved by reducing the rotational speed of the pump shaft dummy 220, and if the process returns to step S400 and determines that the cooling level still needs to be improved, the rotational speed of the pump shaft dummy 220 can be further reduced. However, it should be noted that the lower limit of the rotational speed of the pump shaft dummy 220 is 30 rpm. This lower limit is the minimum rotational speed during normal reactor operation.

[0099] If the temperature is lowered by a refrigerator and low-temperature water is flowed through the test chamber 210 for auxiliary cooling, and the rotation speed of the pump shaft simulation component 220 has been reduced to the lower limit value, but the leakage volume still cannot be maintained stably, it is necessary to abandon this test, reset the preset lower limit value and the parameters of the test system, and retest.

[0100] In some embodiments, when the refrigerator is turned on, low-temperature water is introduced, and the speed of the pump shaft simulator 220 is reduced to 30 rpm, if the leakage rate of the No. 1 seal can be stably maintained at 150 L / h for half an hour, it can be preliminarily determined that the lower limit of the No. 1 seal leakage is 150 L / h. It should be noted that "stable maintenance" here does not mean completely unchanged, but rather a level close to 150 L / h, for example, between 140 L / h and 160 L / h.

[0101] Figure 6 for Figure 3 Flowchart after step S600 in FIG.

[0102] See Figure 2 、 Figure 3 and Figure 6 In some embodiments, step S600 is followed by step S700:

[0103] The wear of the dynamic ring 111 and the static ring 112 is detected. If there is no abnormal wear, the lower limit of the leakage of the No. 1 seal determined in step S600 is valid. If there is abnormal wear, the lower limit of the leakage of the No. 1 seal determined in step S600 is invalid.

[0104] Typically, the absence of a sudden increase in leakage and a temperature spike within the test chamber 210 indicates that the dynamic ring 111 and the stationary ring 112 are not experiencing abnormal wear. However, to improve accuracy, the wear of the dynamic ring 111 and the stationary ring 112 must still be inspected after the test. This inspection is primarily performed visually. If the O-ring is normal, the marks where the sealing panel and the ring meet are continuous and uniform, and the silicon nitride surfaces of the dynamic ring 111 and the stationary ring 112 are normal, then abnormal wear is confirmed.

[0105] Figure 7 for Figure 3 Flowchart before step S100.

[0106] See Figure 2 、 Figure 3 and Figure 7 In some embodiments, step S010 may be performed before step S100:

[0107] Install the No. 1 seal 110 in the test chamber 210 and check the sealing performance of the test chamber 210. If the sealing performance meets the requirements, proceed to the next step. If the sealing performance does not meet the requirements, suspend the test.

[0108] Specifically, after seal No. 1 110 is installed in test chamber 210, liquid is introduced into test chamber 210 via water inlet line 310 to check for leaks and to verify whether its airtightness meets test requirements, thereby improving test accuracy. If the airtightness does not meet the test requirements, the test needs to be suspended and the test system repaired. The test can then be resumed after the airtightness meets the test requirements.

[0109] See Figure 2 、 Figure 3 and Figure 7 In some embodiments, there is a step S020 between step S010 and step S100:

[0110] Injection water is sent into the test chamber 210 to increase the pressure of the test chamber 210 to the No. 1 sealing working pressure.

[0111] Specifically, after checking for airtightness and confirming no problems, test chamber 210 is evacuated and high-pressure injection water is introduced into test chamber 210 via injection water inlet line 310, raising the pressure in test chamber 210 to 158 bar, simulating the actual operating pressure of No. 1 seal 110. Simultaneously, the pressure in No. 1 seal leakage line 320 remains constant at 2.1 bar.

[0112] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0113] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for testing the lower limit of the leakage of the No. 1 seal of the main pump of a nuclear reactor, characterized in that: The steps include: S100 selects a preset lower limit value, adjusts the temperature in the test chamber to a first temperature, and makes the leakage of seal No. 1 corresponding to the first temperature reach the preset lower limit value; S200 rotates the pump shaft simulation and the dynamic ring and monitors the leakage of the No. 1 seal; S300 continuously cools the test cavity; S400 determines whether the leakage of seal No. 1 is stable at the current value; If the leakage of seal No. 1 is stable at the current value in step S500, proceed to step S600; if the leakage of seal No. 1 is not stable at the current value and is increasing at a rate less than the upper limit, increase the cooling level of the test chamber and return to step S400 for another determination. In step S600 , the test system is shut down, and the current value of the leakage of the No. 1 seal maintained stably in step S500 is used as the lower limit of the leakage of the No. 1 seal.

2. The method for testing the lower limit of the leakage of the No. 1 seal of the nuclear reactor main pump according to claim 1, characterized in that: Step S100 includes: S110: raising the temperature of the test chamber to a second temperature; S130: lowering the temperature of the test chamber from the second temperature to the first temperature; The temperature difference between the second temperature and the first temperature is greater than 50 degrees, and the leakage of the No. 1 seal is monitored during step S100.

3. The method for testing the lower limit of the leakage of the No. 1 seal of the nuclear reactor main pump according to claim 2, characterized in that: Step S100 further includes step S120 located between step S110 and step S130: The test chamber is maintained at the second temperature for a preset time period.

4. The method for testing the lower limit of the leakage of the No. 1 seal of the nuclear reactor main pump according to claim 2 or 3, characterized in that: Step S130 includes: S131 starts the refrigerator to cool the test chamber; S132 opens the low-temperature water inflow channel to allow the low-temperature water to flow through the test chamber; S133 determines the temperature of the test chamber. If the temperature of the test chamber is higher than the first temperature, the low-temperature water inflow channel remains open; if the temperature of the test chamber is equal to the first temperature, the low-temperature water inflow channel is closed.

5. The method for testing the lower limit of the leakage of the No. 1 seal of the nuclear reactor main pump according to claim 4, characterized in that: In step S500, the cooling level of the test chamber is improved by: The low-temperature water inflow channel is opened to allow the low-temperature water to flow through the test cavity.

6. The method for testing the lower limit of the leakage of the No. 1 seal of the nuclear reactor main pump according to claim 5, characterized in that: In step S500, the cooling level of the test chamber is improved by: The low-temperature water inflow channel is opened to allow the low-temperature water to flow through the test chamber, and the rotational speed of the pump shaft simulation component is reduced.

7. The method for testing the lower limit of the leakage of the No. 1 seal of the nuclear reactor main pump according to claim 1, characterized in that: In step S500, the cooling level of the test chamber is improved by: The rotational speed of the pump shaft dummy is reduced.

8. The method for testing the lower limit of the leakage of the No. 1 seal of the nuclear reactor main pump according to claim 1, characterized in that: The method further includes step S700 after step S600: The wear of the dynamic ring and the static ring is detected. If there is no abnormal wear, the lower limit of the leakage of the No. 1 seal determined in step S600 is valid; if there is abnormal wear, the lower limit of the leakage of the No. 1 seal determined in step S600 is invalid.

9. The method for testing the lower limit of the leakage of the No. 1 seal of the nuclear reactor main pump according to claim 1, characterized in that: The method further includes step S010 located before step S100: Install seal No. 1 in the test cavity and check the sealing of the test cavity. If the sealing requirements are met, proceed to the next step. If the sealing requirements are not met, suspend the test.

10. The method for testing the lower limit of the leakage of the No. 1 seal of the nuclear reactor main pump according to claim 9, characterized in that: The method further includes step S020 located between step S010 and step S100: Injection water is sent into the test chamber to increase the pressure of the test chamber to the No. 1 sealing working pressure.

11. The method for testing the lower limit of the leakage of the No. 1 seal of the nuclear reactor main pump according to claim 1, characterized in that: The method for obtaining the preset lower limit value is: The parameters of the No. 1 seal are obtained, a No. 1 seal geometric model is established based on the parameters, and a No. 1 seal leakage lower limit simulation calculation is performed based on the No. 1 seal geometric model using simulation software.

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