Method for controlling temperature of flushing water for mechanical seal of nuclear power plant waste heat drain pump and computer readable storage medium

Abstract

The application discloses a kind of nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method and computer readable storage medium, in the ascending stage of nuclear power unit, when the medium temperature of RRA reaches any value in 120 DEG C~135 DEG C, it is switched from double pump operating state to single pump operating state;In the descending stage of nuclear power unit, when the medium temperature of RRA reaches any value in 100 DEG C~145 DEG C, execute pump switching operation, thus the mechanical seal flushing water temperature of residual heat removal pump in outage can be avoided to jump up.In when the medium temperature of RRA reaches any value in 158 DEG C~177 DEG C, then close the isolation valve between RRA and primary loop system, make RRA and primary loop system mutually isolated, so it can prevent the mechanical seal flushing water temperature of residual heat removal pump from exceeding design limit as far as possible, to reduce the risk that mechanical seal damage is caused by the mechanical seal flushing water temperature of residual heat removal pump is too high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear power plant residual heat removal pump, and particularly relates to a nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method and a computer readable storage medium. BACKGROUND

[0002] The reactor residual heat removal system (RRA) is also called reactor shutdown cooling system. In the normal shutdown process of the reactor, when the primary loop temperature drops to 180 DEG C and below, and the pressure drops to 3.0 Mpa per hour, the RRA removes the residual heat of the reactor core, the sensible heat of the primary loop water and equipment, and the heat generated in the primary loop by the running main pump, so that the reactor enters a cold shutdown state. The RRA includes two heat exchangers, two residual heat removal pumps, and related pipelines, valves, and necessary instruments for operation control. The residual heat removal pump, as the driving equipment of the RRA, transports the reactor coolant as the medium. The residual heat removal pump plays an indispensable role in mitigating accidents in the design basis accident of the nuclear power plant. The mechanical seal of each residual heat removal pump adopts a self-circulation flushing scheme, but the mechanical seal of the self-circulation flushing scheme generally has a problem of high mechanical seal flushing water temperature in the high-temperature standby state. Each residual heat removal pump has some design limits of the mechanical seal flushing water temperature. Usually, 75 DEG C is the first alarm temperature value, 85 DEG C is the second alarm temperature value, 110 DEG C is the maximum temperature limit for starting the pump, and if the mechanical seal flushing water temperature reaches 120 DEG C, it is considered that the mechanical seal of the residual heat removal pump is not available. The existing technology has the following defects: the existing residual heat removal pump generally has a problem of mechanical seal flushing water temperature exceeding the design limit in the high-temperature standby state. The high mechanical seal flushing water temperature can cause damage to the mechanical seal, which has an adverse effect on the safe operation of the reactor residual heat removal system. However, there is currently no systematic study on the high-temperature problem of the self-circulation mechanical seal flushing scheme in the field of nuclear power technology, and therefore there is no related solution. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method and a computer readable storage medium to reduce the risk of mechanical seal damage caused by high mechanical seal flushing water temperature of the residual heat removal pump.

[0004] The technical solution adopted by the present application to solve the technical problem is: providing a nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method, which is suitable for a reactor residual heat removal system, the reactor residual heat removal system includes at least two residual heat removal pumps, and the nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method includes the following steps:

[0005] S1, in the on-line stage of the nuclear power unit, the two residual heat removal pumps are operated together;

[0006] S2, judging whether the medium temperature of the reactor residual heat removal system reaches a first preset temperature in the ascending stage of the nuclear power unit, if the judging result is yes, stopping one of the residual heat removal pumps, and keeping the other residual heat removal pump running, the first preset temperature is set as any value in 120℃-135℃;

[0007] judging whether the medium temperature of the reactor residual heat removal system reaches a second preset temperature, if the judging result is yes, closing the isolation valve between the reactor residual heat removal system and the primary loop system, the second preset temperature is set as any value in 158℃-177℃;

[0008] S3, judging whether the medium temperature of the reactor residual heat removal system reaches a third preset temperature in the descending stage of the nuclear power unit, if the judging result is yes, stopping the residual heat removal pump in running state and starting the residual heat removal pump in stopped state, the third preset temperature is set as any value in 100℃-145℃;

[0009] judging whether the medium temperature of the reactor residual heat removal system reaches a second preset temperature, if the judging result is yes, closing the isolation valve between the reactor residual heat removal system and the primary loop system, the second preset temperature is set as any value in 158℃-177℃.

[0010] Preferably, after step S3, further comprising:

[0011] S41, judging whether the isolation valve is closed, if the judging result is yes, starting the residual heat removal pump in stopped state again, and making the two residual heat removal pumps run together.

[0012] Preferably, in step S41, after judging that the isolation valve is closed, before starting the residual heat removal pump in stopped state again, further comprising: judging whether the medium temperature of the reactor residual heat removal system is less than 163℃, and judging whether the mechanical seal flushing water temperature of the stopped residual heat removal pump appears a downward trend; if the judging results are all yes, starting the residual heat removal pump in stopped state again, and making the two residual heat removal pumps run together.

[0013] Preferably, after step S3, further comprising:

[0014] S42, judging whether the isolation valve is closed, if the judging result is yes, judging whether the medium temperature of the reactor residual heat removal system is less than 135℃, if yes, stopping the two residual heat removal pumps.

[0015] Preferably, after step S2 and before step S3, the method further comprises: S21, judging whether the running residual heat removal pump is in failure, if the result of the judgment is yes, stopping the residual heat removal pump in failure and starting another residual heat removal pump in stop state, and after a predetermined condition is met, restarting the residual heat removal pump in failure, the predetermined condition being that the residual heat removal pump in failure is repaired to normal state and the medium temperature of the residual heat removal system is less than 135 DEG C.

[0016] Preferably, after step S2 and before step S3, the method further comprises: S22, judging whether the temperature difference between the two residual heat removal pumps is greater than 60 DEG C, if the result of the judgment is yes, stopping the residual heat removal pump in running state and starting another residual heat removal pump in stop state.

[0017] Preferably, before step S1, the method further comprises:

[0018] S0, judging whether the flow parameter of the residual heat removal system is greater than or equal to a normal value, if the result of the judgment is yes, executing step S1, and if the result of the judgment is no, not executing step S1.

[0019] Preferably, the flow parameter comprises a thermal shield cooling water flow, a mechanical seal cooling water flow and a bearing cooling water flow.

[0020] The step S0 comprises: judging whether the thermal shield cooling water flow is greater than or equal to 1000 L / h, judging whether the mechanical seal cooling water flow is greater than or equal to 700 L / h, and judging whether the bearing cooling water flow is greater than or equal to 500 L / h, if the results of all the judgments are yes, executing step S1, and if the result of one of the judgments is no, not executing step S1.

[0021] Preferably, the second preset temperature is set to be any value in the range of 163 DEG C to 177 DEG C.

[0022] The application further provides a computer readable storage medium, the computer readable storage medium storing a computer program, the computer program being executed by a processor to realize the steps of the nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method.

[0023] The present application has at least the following beneficial effects: in the up-regulation stage of the nuclear power unit, when the medium temperature of the RRA reaches any value in the range of 120-135 DEG C, the double-pump operation state is switched to the single-pump operation state; in the down-regulation stage of the nuclear power unit, when the medium temperature of the RRA reaches any value in the range of 100-145 DEG C, the pump switching operation is performed, so that the temperature jump of the mechanical seal flushing water of the shutdown residual heat removal pump can be avoided. When the medium temperature of the RRA reaches any value in the range of 158-177 DEG C, the isolation valve between the RRA and the primary loop system is closed, so that the RRA and the primary loop system are isolated from each other, thus preventing the temperature of the mechanical seal flushing water of the residual heat removal pump from exceeding the design limit value as much as possible, thereby reducing the risk of mechanical seal damage caused by the excessively high temperature of the mechanical seal flushing water of the residual heat removal pump. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the present application, the present application will be further described below in combination with the drawings and embodiments, in which:

[0025] Figure 1 is a flow chart of the nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method of some embodiments of the present application;

[0026] Figure 2 is a temperature-time curve of the mechanical seal flushing water of the residual heat removal pump and a medium temperature-time curve of the RRA;

[0027] Figure 3 is a fitting curve diagram of the temperature of the mechanical seal flushing water of the residual heat removal pump and the medium temperature of the RRA;

[0028] Figure 4 is a temperature-time curve diagram of the primary loop medium temperature and the mechanical seal flushing water temperature of the two residual heat removal pumps when the method of an embodiment of the present application is applied in the up-regulation stage of a certain nuclear power unit;

[0029] Figure 5 is a temperature-time curve diagram of the primary loop medium temperature and the mechanical seal flushing water temperature of the two residual heat removal pumps when the method of an embodiment of the present application is applied in the down-regulation stage of a certain nuclear power unit;

[0030] Figure 6 is a flow chart of the nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method of some embodiments of the present application;

[0031] Figure 7 is a flow chart of the nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method of some embodiments of the present application;

[0032] Figure 8is a flow chart of a nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method according to another embodiment of the present application;

[0033] Figure 9 is a flow chart of a nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method according to another embodiment of the present application;

[0034] Figure 10 is a flow chart of a nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method according to another embodiment of the present application;

[0035] Figure 11 is a flow chart of a nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method according to another embodiment of the present application. DETAILED DESCRIPTION

[0036] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0037] As described in the background, the mechanical seal of the existing residual heat removal pump adopts a self-circulation flushing scheme. On this basis, the temperature of the mechanical seal flushing water in the high-temperature standby state generally exceeds the design limit. Through analysis, this is due to the insufficient natural circulation capacity of the mechanical seal cooler of the residual heat removal pump in the hot standby state. In order to avoid the high temperature of the mechanical seal return water of the residual heat removal pump causing damage to the mechanical seal, the present application proposes a nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method (hereinafter referred to as the mechanical seal flushing water temperature control method). Through the mechanical seal flushing water temperature control method, the temperature of the residual heat removal pump mechanical seal flushing water can be effectively controlled to not exceed the design limit (in different embodiments, the design limit can be set to 75℃ or 85℃ or 110℃ or 120℃), thereby avoiding the situation of mechanical seal damage caused by high temperature.

[0038] The mechanical seal flushing water temperature control method of the present application is applicable to a reactor residual heat removal system (hereinafter referred to as RRA), and the RRA includes at least two residual heat removal pumps. Hereinafter, only the case of two residual heat removal pumps will be described as an example. In some embodiments, the RRA can include more than three residual heat removal pumps.

[0039] Please refer to Figure 1 The mechanical seal flushing water temperature control method of the present application at least includes the following steps:

[0040] S1, in the up-regulation stage of the nuclear power unit, two residual heat removal pumps are operated together. Specifically, in the up-regulation stage of the nuclear power unit (the platform period of 25 bar pressure), the medium temperature of the primary loop system shows an upward trend, and the medium temperature of the RRA also shows an upward trend following the medium temperature of the primary loop system. Two residual heat removal pumps are operated together (double pump operation) to export the heat of the primary loop system.

[0041] S2, in the up-regulation stage of the nuclear power unit, it is judged whether the medium temperature of the RRA reaches a first preset temperature, if the judgment result is yes, one of the residual heat removal pumps is stopped, and the other residual heat removal pump is kept running (single pump operation). Wherein, the first preset temperature is set to any value in 120℃-135℃. That is, the first preset temperature can be 120℃, 135℃ or any value between 120℃-135℃. If the judgment result is no, the double pump operation state is continued.

[0042] Specifically, the medium temperature of the primary loop system shows an upward trend, and the medium temperature of the RRA shows an upward trend following it. Please refer to the graph shown in Figure 2 , Figure 2 The "F1 RRA system temperature" in the graph refers to the medium temperature of the RRA, and the "F1 RRA001 PO mechanical seal flushing water temperature" refers to the mechanical seal flushing water temperature of one of the residual heat removal pumps of the RRA. Figure 2 The graph shows the trend of the mechanical seal flushing water temperature of the residual heat removal pump with the change of the medium temperature of the RRA, that is, the mechanical seal flushing water temperature of the residual heat removal pump is closely related to the medium temperature of the RRA. From Figure 2 It can be seen that after the medium temperature of the RRA reaches 120℃ (corresponding to the mechanical seal flushing water temperature of the residual heat removal pump reaching about 60℃), both of them show a steep upward trend, the medium temperature of the RRA jumps from 120℃ to about 160℃, and the mechanical seal flushing water temperature of the residual heat removal pump jumps from 60℃ to about 80℃. Therefore, when the medium temperature of the RRA reaches 120℃, the double pump operation state is switched to the single pump operation state, which can avoid the mechanical seal flushing water temperature of the stopped residual heat removal pump jumping. On the basis of 120℃, a certain margin is added, which can expand the theoretical limit value of 120℃ to the interval of 120℃-135℃.

[0043] Simultaneously, in step S2, it is also determined whether the medium temperature of the RRA has reached the second preset temperature. If the determination result is yes, the isolation valve between the RRA and the primary loop system is closed, and the second preset temperature is set to any value between 158℃ and 177℃. That is, the second preset temperature can be 158℃, 177℃, or any value between 158℃ and 177℃. In other words, the second preset temperature is greater than the first preset temperature. After the medium temperature of the RRA has exceeded the first preset temperature, further measures need to be taken to prevent the mechanical seal flushing water temperature of the shut-down waste heat discharge pump from becoming too high.

[0044] Specifically, please refer to Figure 3 , Figure 3 The black and red lines in the diagram represent two waste heat removal pumps, respectively. Figure 3 To adopt Figure 2 The chart shown is a fitted curve obtained after data fitting. From... Figure 3 It can be seen that when the medium temperature of the RRA reaches 180℃, the mechanical seal flushing water temperature of the waste heat discharge pump can reach 108℃, which is close to the maximum allowable temperature limit for pump start-up (110℃). Therefore, if the RRA and the primary circuit system are isolated when the medium temperature of the RRA reaches 180℃, the mechanical seal flushing water temperature of the shut-down waste heat discharge pump is very likely to exceed the maximum allowable temperature limit for pump start-up (110℃), or even exceed the limit of 120℃. Therefore, conservatively speaking, the maximum value of the second preset temperature is set to 177℃. At the latest, when the medium temperature of the RRA is judged to reach 177℃, the isolation valve between the RRA and the primary circuit system is closed, so that the RRA and the primary circuit system are isolated from each other. The RRA system no longer receives heat from the primary circuit system, which can prevent the mechanical seal flushing water temperature of the waste heat discharge pump from exceeding the maximum allowable temperature limit for pump start-up (110℃) and the limit of 120℃ as much as possible.

[0045] Please also refer to Table 1 below, which contains a selection of data. Figure 2 The chart shows some values. It can be seen that if the RRA and primary circuit system are isolated when the medium temperature in the RRA reaches approximately 159℃, the mechanical seal flushing water temperature of the shut-down waste heat discharge pump reaches approximately 75℃. Therefore, if the RRA and primary circuit system are isolated after the medium temperature in the RRA exceeds 158℃, the mechanical seal flushing water temperature of the shut-down waste heat discharge pump is very likely to exceed the first alarm temperature value (75℃). Therefore, conservatively, the minimum value of the second preset temperature is set to 158℃. The isolation valve between the RRA and primary circuit system is closed as early as when the medium temperature in the RRA reaches 158℃, isolating the RRA and primary circuit system from each other. This can prevent the mechanical seal flushing water temperature of the waste heat discharge pump from exceeding the first alarm temperature value (75℃) as much as possible.

[0046] Medium temperature of the RRA (°C) Mechanical seal flush water temperature of the residual heat removal pump (°C) 158.9772949 76.00041962 158.9764862 75.98453522 158.9756775 75.96865845 158.9748688 75.95277405 158.9740601 75.93688965 158.9732513 75.92100525 158.9336243 75.14273071 158.9328156 75.12685394 158.9320068 75.11096954 158.9311981 75.09508514 158.9303894 75.07920074 158.9295807 75.06331635 158.928772 75.04743195 158.9279633 75.03155518 158.9271545 75.01567078 158.9263458 74.99978638

[0047] Table 1

[0048] S3, in the downlink stage of the nuclear power unit, judging whether the medium temperature of the RRA reaches a third preset temperature, if the judging result is yes, stopping the operation of the residual heat removal pump in the running state, and starting the operation of the residual heat removal pump in the stopped state (pump switching operation). The third preset temperature is set to any value in 100℃-145℃. Specifically, unlike the uplink stage of the nuclear power unit, the medium temperature of the primary loop system as a whole begins to show a downward trend, and the medium temperature of the RRA begins to show a downward trend. During the downlink stage of the nuclear power unit, when the medium temperature of the RRA reaches any value between 100℃ and 145℃, the pump switching operation can be performed. Similarly, the same as step S2, in step S3, it is also necessary to judge whether the medium temperature of the RRA reaches a second preset temperature, if the judging result is yes, closing the isolation valve between the RRA and the primary loop system, and the second preset temperature is also set to any value in 158℃-177℃.

[0049] In summary, in the uplink stage of the nuclear power unit, when the medium temperature of the RRA reaches any value in 120℃-135℃, the state is switched from the double-pump operation state to the single-pump operation state; in the downlink stage of the nuclear power unit, when the medium temperature of the RRA reaches any value in 100℃-145℃, the pump switching operation is performed, which can avoid the temperature jump of the mechanical seal flushing water of the stopped residual heat removal pump. When the medium temperature of the RRA reaches any value in 158℃-177℃, the isolation valve between the RRA and the primary loop system is closed, so that the RRA and the primary loop system are isolated from each other, which can prevent the temperature of the mechanical seal flushing water of the residual heat removal pump from exceeding the design limit as much as possible.

[0050] Please refer to Figure 4 and Figure 5 , Figure 4 Fig. 1 shows the temperature-time curve of the primary loop medium temperature and the mechanical seal flushing water temperature of two residual heat removal pumps when the method of an embodiment of the present application is applied to the uplink stage of a certain nuclear power unit; Figure 5 Fig. 2 shows the temperature-time curve of the primary loop medium temperature and the mechanical seal flushing water temperature of two residual heat removal pumps when the method of an embodiment of the present application is applied to the downlink stage of a certain nuclear power unit. In the figures, Figure 4 and Figure 5 the blue line legend refers to the temperature curve of the primary loop medium, and the red line legend and the yellow line legend respectively refer to the temperature curves of the two residual heat removal pumps. Figure 5 The green curve in Fig. 1 refers to the temperature curve of the RRA. Figure 4 and Figure 5The area not shown in the temperature curve of the RRA represents the area where the temperature curve of the RRA coincides with the temperature curve of the primary loop medium, and both have the same temperature change trend.

[0051] like Figure 4 As shown, during the up-current phase of the nuclear power unit, at 120°C, one of the waste heat removal pumps is shut down while the other continues operation (single-pump switching). The shut-down pump exhibits a heating trend, while the operating pump shows a cooling trend, resulting in an intersection point in their temperature curves. At 135°C, one of the waste heat removal pumps is shut down again, while the other continues operation (pump switching). Again, the shut-down pump shows a heating trend, while the operating pump shows a cooling trend, again resulting in an intersection point in their temperature curves. In other words, during the up-current phase of the nuclear power unit, within the temperature range of 120°C to 135°C, the operation of the two waste heat removal pumps can be switched multiple times, and the mechanical seal flushing water temperature of both pumps can be controlled within the design limits.

[0052] like Figure 5 As shown, during the down-flow phase of the nuclear power unit, at 100℃, one of the waste heat removal pumps is shut down, and the other is switched on to continue operation (pump-off operation). The shut-down waste heat removal pump shows a heating trend, while the operating waste heat removal pump shows a cooling trend, causing the temperature curves of the two waste heat removal pumps to intersect. At 145℃, one of the waste heat removal pumps is shut down, and the other is switched on to continue operation (pump-off operation). The shut-down waste heat removal pump shows a heating trend, while the operating waste heat removal pump shows a cooling trend, causing the temperature curves of the two waste heat removal pumps to intersect. Therefore, during the down-flow phase of the nuclear power unit, within the temperature range of 100℃ to 145℃, the mechanical seal flushing water temperature of both waste heat removal pumps can be controlled within the design limits.

[0053] Furthermore, in some embodiments, the second preset temperature can be set to any value between 163°C and 177°C. That is, the minimum value of the second preset temperature is set to 163°C. Figure 2 and Figure 3 It can be seen that when the medium temperature of the RRA reaches 163℃, the isolation valve between the RRA and the primary circuit system is closed to isolate the RRA and the primary circuit system from each other. This can prevent the temperature of the mechanical seal flushing water of the residual heat discharge pump from exceeding approximately 91℃. 91℃ is between the first alarm temperature value (75℃) and the maximum allowable pump start temperature limit (110℃). Therefore, the mechanical seal flushing water temperature meets the maximum allowable pump start temperature limit while relatively delaying the isolation of the RRA.

[0054] Please see Figure 6In some embodiments, after step S3, the method further includes: S41, determining whether the isolation valve is closed; if the determination result is yes, restarting the waste heat discharge pump that is in the shutdown state, so that both waste heat discharge pumps operate together. That is, if it is determined that the isolation valve is closed, the operation can be restored from a single-pump operation state to a state where both waste heat discharge pumps operate together (dual-pump operation). Specifically, after the isolation valve is closed, the medium temperature of the RRA will gradually decrease, and the temperature of the mechanical seal flushing water of the waste heat discharge pump will also gradually decrease, so the temperature of the mechanical seal flushing water of the waste heat discharge pump can be basically controlled to not exceed the design limit. However, in some other embodiments, after step S3, the waste heat discharge pump that is in the shutdown state may not be restarted, and only one waste heat discharge pump may be kept running (single-pump operation). Resuming dual-pump operation after step S3 can accelerate the cooling of the RRA.

[0055] Furthermore, considering it more conservatively, such as Figure 7 As shown, in some embodiments, before restarting the shut-down waste heat discharge pump after determining that the isolation valve is closed in step S41, the steps may further include: determining whether the medium temperature of the RRA is less than 163°C, and determining whether the mechanical seal flushing water temperature of the waste heat discharge pump shows a downward trend. If both determinations are yes, the shut-down waste heat discharge pump is restarted. If one of the determinations is no, the shut-down waste heat discharge pump is not started, and the previously operating waste heat discharge pump continues to operate (maintaining single pump operation). That is, the conditions for restarting the shut-down waste heat discharge pump include (1) the isolation valve between the RRA and the primary loop system is closed, (2) the medium temperature of the RRA drops to below 163°C, and (3) the mechanical seal flushing water temperature of the waste heat discharge pump shows a downward trend.

[0056] Please see Figure 8 In some embodiments, after step S3, the method further includes: S42, determining whether the isolation valve is closed; if the determination result is yes, determining whether the medium temperature of the reactor waste heat removal system is less than 135°C; if yes, then shutting down both waste heat removal pumps simultaneously. As mentioned above, after the isolation valve is closed, the medium temperature of the RRA will gradually decrease, and the temperature of the mechanical seal flushing water of the waste heat removal pump will also gradually decrease, thus basically controlling the temperature of the mechanical seal flushing water of the waste heat removal pump to not exceed the design limit. Therefore, after the medium temperature of the RRA drops to less than 135°C, the two waste heat removal pumps can be shut down, and the RRA will then rely on natural cooling. Of course, in other embodiments, the two waste heat removal pumps can also be kept running, maintaining a single-pump or dual-pump operation.

[0057] Please see Figure 9In some embodiments, after step S2 and before step S3, the method further comprises: S21, judging whether the running residual heat removal pump has a fault, if the result of the judgment is yes, stopping the residual heat removal pump with the fault and starting another residual heat removal pump in the stopped state (i.e. switching pump operation), and after meeting a predetermined condition, restarting the residual heat removal pump with the fault, the predetermined condition being that the residual heat removal pump with the fault is repaired to a normal state and the medium temperature of the RRA is less than 135°C. Specifically, when judging whether the running residual heat removal pump has a fault, it can be further judged whether the fault is a fault that can be quickly solved or a fault that cannot be solved in a short period of time. If it is a fault that can be quickly solved, the instruction of switching pump operation is still executed, and after meeting the predetermined condition, the residual heat removal pump with the fault is restarted. If it is a fault that cannot be solved in a short period of time, it can be decided by the command department whether to retreat the nuclear power unit.

[0058] When the medium temperature of the RRA is reduced to below 135°C, the normal operation can be performed according to the CPR1000 operation regulation.

[0059] Please refer to Figure 10 In some embodiments, after step S2 and before step S3, the method further comprises: S22, judging whether the temperature difference between the two residual heat removal pumps is greater than 60°C, if the result of the judgment is yes, stopping the residual heat removal pump in the running state and starting the other residual heat removal pump in the stopped state (i.e. switching pump operation). If the result of the judgment is no, the original single pump operation state is maintained. Specifically, when the temperature difference between the two residual heat removal pumps is too large, the residual heat removal pump with lower temperature is prone to shaft jamming, therefore, after switching to single pump operation, the temperature difference between the two residual heat removal pumps can be further judged, if the temperature difference between the two residual heat removal pumps is greater than 60°C, in order to reduce the risk of shaft jamming of the residual heat removal pump with lower temperature, the switching pump operation can be performed.

[0060] In some embodiments, before step S1, the method further comprises: S0, judging whether the flow parameter of the RRA is greater than or equal to a normal value, if the result of the judgment is yes, step S1 is performed. If the result of the judgment is no, step S1 is not performed. Specifically, the flow parameter of the RRA also affects the temperature of the mechanical seal flushing water of the residual heat removal pump, for example, when the flow of the RRA is insufficient, the temperature of the mechanical seal flushing water of the residual heat removal pump is difficult to be reduced, and the high temperature may cause equipment damage. Therefore, before starting the two residual heat removal pumps, it can be ensured that the flow parameter of the RRA is greater than or equal to the normal value.

[0061] Further, please refer to Figure 11In some embodiments, the flow parameters can include the heat shield cooling water flow, the mechanical seal cooling water flow and the bearing cooling water flow. Step SO includes judging whether the heat shield cooling water flow is greater than or equal to 1000 L / h, judging whether the mechanical seal cooling water flow is greater than or equal to 700 L / h, judging whether the bearing cooling water flow is greater than or equal to 500 L / h, and executing step S1 if all the judgments are yes. If one of the judgments is no, step S1 is not executed. Specifically, the heat shield cooling water flow, the mechanical seal cooling water flow and the bearing cooling water flow can be obtained by reading the readings of the corresponding flow meters at the nuclear power site.

[0062] In some embodiments, the present application also provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the method for controlling the temperature of the mechanical seal flushing water of a residual heat removal pump of a nuclear power plant according to any one of the embodiments of the present application.

[0063] It can be understood that the above embodiments only express the preferred embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the patent scope of the present application; it should be pointed out that for those skilled in the art, the above technical features can be freely combined without departing from the concept of the present application, and several modifications and improvements can be made, which all belong to the protection scope of the present application; therefore, any equivalent transformation and modification within the scope of the claims of the present application shall belong to the scope of the claims of the present application.

Claims

1. A method for controlling the temperature of a mechanical seal flush water of a nuclear power plant residual heat removal pump, suitable for a reactor residual heat removal system comprising at least two residual heat removal pumps, characterized in that, The nuclear power plant residual heat removal pump mechanical seal flushing water temperature control method comprises the following steps: S1, in the ascending stage of the nuclear power unit, two residual heat removal pumps are operated together; S2, in the ascending stage of the nuclear power unit, it is judged whether the medium temperature of the reactor residual heat removal system reaches a first preset temperature, if the judgment result is yes, one of the residual heat removal pumps is stopped, and the other residual heat removal pump is kept running, the first preset temperature is set to any value in 120-135℃; It is judged whether the medium temperature of the reactor residual heat removal system reaches a second preset temperature, if the judgment result is yes, the isolation valve between the reactor residual heat removal system and the primary loop system is closed, the second preset temperature is set to any value in 158-177℃; S3, in the descending stage of the nuclear power unit, it is judged whether the medium temperature of the reactor residual heat removal system reaches a third preset temperature, if the judgment result is yes, the residual heat removal pump in running state is stopped, and the residual heat removal pump in stopped state is started, the third preset temperature is set to any value in 100-145℃; It is judged whether the medium temperature of the reactor residual heat removal system reaches a second preset temperature, if the judgment result is yes, the isolation valve between the reactor residual heat removal system and the primary loop system is closed, the second preset temperature is set to any value in 158-177℃.

2. The nuclear power plant residual heat removal pump mechanical seal flush water temperature control method according to claim 1, characterized by, After step S3, it further comprises: S41, it is judged whether the isolation valve is closed, if the judgment result is yes, the residual heat removal pump in stopped state is started again to make two residual heat removal pumps operate together.

3. The nuclear power plant RCP mechanical seal flush water temperature control method according to claim 2, characterized by, In step S41, after the isolation valve is closed, before the residual heat removal pump in stopped state is started again, it can further comprise: judging whether the medium temperature of the reactor residual heat removal system is less than 163℃, and judging whether the mechanical seal flushing water temperature of the stopped residual heat removal pump appears a downward trend; if all the judgment results are yes, the residual heat removal pump in stopped state is started again to make two residual heat removal pumps operate together.

4. The nuclear power plant RCP mechanical seal flush water temperature control method according to claim 1, characterized by, After step S3, it further comprises: S42, it is judged whether the isolation valve is closed, if the judgment result is yes, it is judged whether the medium temperature of the reactor residual heat removal system is less than 135℃, if yes, two residual heat removal pumps are stopped together.

5. The nuclear power plant RCP mechanical seal flush water temperature control method according to claim 1, characterized by, After step S2, before step S3, it further comprises: S21, it is judged whether the residual heat removal pump in running state has a fault, if the judgment result is yes, the residual heat removal pump with fault is stopped, and the other residual heat removal pump in stopped state is started, after a predetermined condition is met, the residual heat removal pump with fault is restarted, the predetermined condition is that the residual heat removal pump with fault is repaired to normal state and the medium temperature of the reactor residual heat removal system is less than 135℃.

6. The nuclear power plant RCP mechanical seal flush water temperature control method of claim 1, wherein, After step S2 and before step S3, further comprising: S22, judging whether the temperature difference between the two waste heat removal pumps is greater than 60℃, if the result is yes, stopping the operation of the waste heat removal pump in the running state, and starting the operation of the other waste heat removal pump in the stopped state.

7. The method for controlling the temperature of the mechanical seal flush water of a nuclear power plant residual heat removal pump according to claim 1, characterized by, Before step S1, further comprising: S0, judging whether the flow parameter of the reactor waste heat removal system is greater than or equal to the normal value, if the result is yes, executing step S1, if the result is no, not executing step S1.

8. The nuclear power plant RCP mechanical seal flush water temperature control method according to claim 7, characterized by, The flow parameter comprises the heat shield cooling water flow, the mechanical seal cooling water flow and the bearing cooling water flow. The step S0 comprises: judging whether the heat shield cooling water flow is greater than or equal to 1000L / h, judging whether the mechanical seal cooling water flow is greater than or equal to 700L / h, judging whether the bearing cooling water flow is greater than or equal to 500L / h, if all the results are yes, executing step S1, if one of the results is no, not executing step S1.

9. The method for controlling the temperature of the mechanical seal flush water of a nuclear power plant residual heat removal pump according to claim 1, characterized by, The second preset temperature is set to any value in 163℃-177℃.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is executed by the processor to realize the steps of the nuclear power plant waste heat removal pump mechanical seal flushing water temperature control method in any one of claims 1-9.

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