A circulating system for a multi-mode in-containment refueling water tank after water quality anomaly

Abstract

The present application relates to a kind of multi-mode inner containment water tank water quality after abnormal circulation system of refueling.The system includes first circulation loop, second circulation loop and third circulation loop, first circulation loop includes first PTR purification pump and first PTR inlet valve, second circulation loop includes second PTR purification pump and second PTR inlet valve, and third circulation loop includes first EHR pump and first heat exchanger.After monitoring the water quality in the inner containment water tank of refueling, first circulation loop, second circulation loop and third circulation loop are started simultaneously and run for a preset time.The present application fills the scheme of circulating in the inner containment water tank of refueling after abnormal water quality in specific mode, solves the actual demand of nuclear power unit, so that nuclear power unit can be more safely and stably operated.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant operation monitoring, and more specifically, to a multi-mode containment refueling water tank water quality abnormality recirculation system. Background Technology

[0002] Before sampling, the IRWST (Inside Refueling Water Tank) in the containment of a nuclear power plant needs to be circulated, which means that the water in the IRWST is stirred evenly to make the sampling more accurate.

[0003] As shown in Table 1, six operating modes for the reactor are defined based on reactivity, core thermal power, and average reactor coolant temperature. In addition, there is a third mode, known as the complete unloading mode, which occurs after all nuclear fuel has been transferred from the reactor pressure vessel to the PTR system's spent fuel pool.

[0004] Table 1. Definitions of 6 operating modes during reactor operation (a) Excluding heat of decay.

[0005] (b) All bolts on the reactor pressure vessel top cover are in full tension.

[0006] Based on the extent of primary loop integrity failure, Mode 5 can be divided into a primary loop pressurization-capable state and a primary loop non-pressurization-capable state. The primary loop pressurization-capable state refers to the state when the pressure vessel top cover vent sleeve, pressurizer, and atmospheric blind flange are all installed. The primary loop non-pressurization-capable state refers to the state when at least one of the reactor pressure vessel top cover vent sleeve, pressurizer, and atmospheric blind flange has been removed.

[0007] (c) One or more bolts on the top cover of the reactor pressure vessel are not in a fully tensioned state.

[0008] Table 2 shows the mitigation measures and follow-up action strategies required in the technical specifications after the IRWST refueling tank inside the containment experiences water quality non-compliance. As can be seen from Table 2, once the IRWST water quality becomes non-compliant, it needs to be restored within 8 hours. Currently, three RIS low-pressure safety injection pumps are started simultaneously for circulation, with a total mixing flow rate of 360 m³ / h. Simulation calculations show that the boron concentration in the IRWST can be uniformly adjusted within 7 hours.

[0009] Table 2. Technical Specifications for In-Containment Refueling Tanks (IRWSTs) like Figure 1The dashed box indicates the existing IRWST refueling tank circulation method within the containment, which involves circulation via three rows of RIS system low-pressure safety pumps. However, in modes 4, 5, and 6, the RIS system low-pressure safety pumps must also function as the RHR system to remove heat from the primary loop. In these modes, the RIS system low-pressure safety pumps can no longer circulate the IRWST tank. The operation of the RIS low-pressure safety pumps in modes 4, 5, and 6 is as follows: Figure 2 As indicated by the dashed box. Therefore, a new solution is needed for modes 4, 5, and 6 to replace the mixing function of the low-pressure safety pump, while also meeting the principle in the technical specifications to restore the water quality of the IRWST tank inside the containment within 8 hours, in order to fill the gaps in the existing design. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to provide a recirculation system for the refueling tank inside the containment vessel in a multi-mode configuration when the water quality is abnormal.

[0011] The technical solution adopted by the present invention to solve its technical problem is: to construct a multi-mode containment refueling water tank water quality abnormality recirculation system, including a first circulation loop, a second circulation loop and a third circulation loop; The first circulation loop includes a first PTR purification pump and a first PTR inlet valve. The first end of the first PTR purification pump is connected to the first end of the first PTR inlet valve via a pipeline. The second end of the first PTR inlet valve is connected to the first outlet of the refueling tank inside the containment via a pipeline. The second end of the first PTR purification pump is connected to the first inlet of the refueling tank inside the containment via a pipeline. The second circulation loop includes a second PTR purification pump and a second PTR inlet valve. The first end of the second PTR purification pump is connected to the first end of the second PTR inlet valve via a pipeline. The second end of the second PTR inlet valve is connected to the second outlet of the refueling tank inside the containment via a pipeline. The second end of the second PTR purification pump is connected to the first inlet of the refueling tank inside the containment via a pipeline. The third circulation loop includes a first EHR pump and a first heat exchanger. The first end of the first EHR pump is connected to the first spare outlet of the refueling tank inside the containment via a pipe. The second end of the first EHR pump is connected to the first end of the first heat exchanger via a pipe. The second end of the first heat exchanger is connected to the second inlet of the refueling tank inside the containment via a pipe. Upon detecting an abnormality in the water quality of the refueling tank inside the containment vessel, the first circulation loop, the second circulation loop, and the third circulation loop are simultaneously activated and run for a preset time.

[0012] Furthermore, in the multi-mode containment refueling tank water quality abnormality recirculation system described in this invention, the third circulation loop also includes a third check valve, a third orifice plate, and a fourth orifice plate. The second end of the first heat exchanger is connected to the first end of the third check valve via a pipe. The second end of the third check valve is connected to the first end of the third orifice plate via a pipe. The second end of the third orifice plate is connected to the second inlet of the refueling tank inside the containment via a pipe. The first end of the first heat exchanger is connected to the first end of the fourth orifice plate via a pipe. The second end of the fourth orifice plate is connected to the second end of the first EHR pump via a pipe.

[0013] Furthermore, in the multi-mode containment refueling tank water quality abnormality recirculation system described in this invention, the third circulation loop also includes at least one electric valve and at least one manual valve, the at least one electric valve and at least one manual valve are installed in the third circulation loop, and one of the electric valves is connected in parallel with the fourth throttling orifice plate.

[0014] Furthermore, in the multi-mode containment refueling tank water quality abnormality recirculation system described in this invention, a fourth circulation loop is also included, which includes a second EHR pump and a second heat exchanger. The first end of the second EHR pump is connected to the second spare outlet of the refueling tank inside the containment via a pipe, the second end of the second EHR pump is connected to the first end of the second heat exchanger via a pipe, and the second end of the second heat exchanger is connected to the third inlet of the refueling tank inside the containment via a pipe. If the third loop malfunctions during operation, the third loop will be shut down and the fourth loop will be started.

[0015] Furthermore, in the multi-mode containment refueling tank water quality abnormality recirculation system described in this invention, the fourth circulation loop also includes a fourth check valve, a fifth orifice plate, and a sixth orifice plate. The second end of the second heat exchanger is connected to the first end of the fourth check valve via a pipe. The second end of the fourth check valve is connected to the first end of the fifth orifice plate via a pipe. The second end of the fifth orifice plate is connected to the third inlet of the refueling tank inside the containment via a pipe. The first end of the second heat exchanger is connected to the first end of the sixth orifice plate via a pipe. The second end of the sixth orifice plate is connected to the second end of the second EHR pump via a pipe.

[0016] Furthermore, in the multi-mode containment refueling tank water quality abnormality recirculation system described in this invention, the fourth circulation loop also includes at least one electric valve and at least one manual valve, the at least one electric valve and at least one manual valve are installed in the fourth circulation loop, and one of the electric valves is connected in parallel with the sixth throttling orifice plate.

[0017] Furthermore, in the multi-mode containment refueling tank water quality abnormality recirculation system described in this invention, at least one RIS low-pressure safety injection pump circulation loop is also included for water circulation in the containment refueling tank. In the fully unloading mode, at least one of the first circulation loop, the second circulation loop, the third circulation loop, and the RIS low-pressure injection pump circulation loop is selected for circulation operation.

[0018] Furthermore, in the multi-mode containment refueling tank water quality abnormality recirculation system described in this invention, the first circulation loop also includes a first check valve, a first throttling orifice plate, at least one manual isolation valve and at least one electric valve. The second end of the first PTR purification pump is connected to the first end of the first check valve via a pipeline. The second end of the first check valve is connected to the first end of the first orifice plate via a pipeline. The second end of the first orifice plate is connected to the first inlet of the refill water tank inside the containment via a pipeline. The at least one manual isolation valve and the at least one electric valve are installed in the first circulation loop.

[0019] Furthermore, in the multi-mode containment refueling tank water quality abnormality recirculation system described in this invention, the second circulation loop also includes a second check valve, a second throttling orifice plate, at least one manual isolation valve and at least one electric valve. The second end of the second PTR purification pump is connected to the first end of the second check valve through a pipeline. The second end of the second check valve is connected to the first end of the second orifice plate through a pipeline. The second end of the second orifice plate is connected to the first inlet of the refill water tank inside the containment through a pipeline. The at least one manual isolation valve and the at least one electric valve are installed in the second circulation loop.

[0020] Furthermore, in the multi-mode containment refueling tank water quality abnormality recirculation system described in this invention, the first circulation loop is connected to the first RCV charging pump. If the first RCV charging pump is started during the operation of the first circulation loop, the first circulation loop is shut down. The second circulation loop is connected to the second RCV charging pump. If the second RCV charging pump is started during the operation of the second circulation loop, the second circulation loop is shut down.

[0021] The present invention provides a multi-mode recirculation system for refueling tanks within containment after water quality abnormalities, which has the following advantages: The present invention fills the gap in the solution for recirculation after water quality abnormalities in refueling tanks within containment under specific modes, solves the actual needs of nuclear power units, and enables nuclear power units to operate more safely and stably. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic diagram of the low-pressure safety injection pump for mixing the IRWST water tank in existing technology; Figure 2 This is a schematic diagram of the operation mode of the RIS low-pressure safety injection pump in modes 4, 5, and 6 of the existing technology; Figure 3 This is a schematic diagram of the recirculation system provided in this embodiment of the invention after the water quality of the refueling tank inside the containment becomes abnormal. Figure 4 This is a schematic diagram of the structure of the recirculation system in the containment water tank under multiple modes provided in this embodiment of the invention, which is used to address water quality abnormalities. Detailed Implementation

[0023] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] In a preferred embodiment, reference Figure 3 and Figure 4 The multi-mode containment refueling tank water quality abnormality circulation system of this embodiment includes a first circulation loop 10, a second circulation loop 20 and a third circulation loop 30. The first circulation loop 10, the second circulation loop 20 and the third circulation loop 30 will be described below.

[0025] The first circulation loop 10 includes a first PTR purification pump 101 and a first PTR inlet valve 102. The first end of the first PTR purification pump 101 is connected to the first end of the first PTR inlet valve 102 via a pipe. The second end of the first PTR inlet valve 102 is connected to the first outlet of the refueling tank inside the containment via a pipe. The second end of the first PTR purification pump 101 is connected to the first inlet of the refueling tank inside the containment via a pipe.

[0026] The second circulation loop 20 includes a second PTR purification pump 201 and a second PTR inlet valve 202. The first end of the second PTR purification pump 201 is connected to the first end of the second PTR inlet valve 202 via a pipe. The second end of the second PTR inlet valve 202 is connected to the second outlet of the refueling tank inside the containment via a pipe. The second end of the second PTR purification pump 201 is connected to the first inlet of the refueling tank inside the containment via a pipe.

[0027] The third circulation loop 30 includes a first EHR pump 301 and a first heat exchanger 302. The first end of the first EHR pump 301 is connected via a pipe to the first standby outlet of the refueling tank inside the containment. The second end of the first EHR pump 301 is connected via a pipe to the first end of the first heat exchanger 302. The second end of the first heat exchanger 302 is connected via a pipe to the second inlet of the refueling tank inside the containment. Figure 3 As can be seen from the diagram, in this embodiment, after the first backup outlet is activated, the positions of the first backup outlet and the second inlet on the refill tank inside the containment are staggered to achieve a better turbidity effect.

[0028] Upon detecting an abnormal water quality in the refueling tank within the containment vessel, the first circulation loop 10, the second circulation loop 20, and the third circulation loop 30 are simultaneously activated and run for a preset time. It can be understood that "simultaneous activation" here means that the first circulation loop 10, the second circulation loop 20, and the third circulation loop 30 start at approximately the same time. Considering actual operation and the equipment startup process, the requirement of "simultaneous activation" is met if the first circulation loop 10, the second circulation loop 20, and the third circulation loop 30 complete activation within a short period of time.

[0029] After the first circulation loop 10, the second circulation loop 20, and the third circulation loop 30 are running, it is calculated that the circulation flow rate of the first PTR purification pump 101 used in the first circulation loop 10 is 90 m³ / h, the circulation flow rate of the second PTR purification pump 201 used in the second circulation loop 20 is 90 m³ / h, and the circulation flow rate of the first EHR pump 301 used in the third circulation loop 30 is 200 m³ / h. Therefore, the total circulation flow rate of the first circulation loop 10, the second circulation loop 20, and the third circulation loop 30 is 380 m³ / h. The circulation flow rate is slightly larger than the flow rate when the three rows of RIS low-pressure safety injection pumps are running simultaneously. It can meet the circulation requirements in modes 4, 5, and 6 and is slightly better than the existing technology of using three rows of RIS low-pressure safety injection pumps to run simultaneously.

[0030] Furthermore, based on the circulation requirements, namely that the total circulation flow rate is at least one times the water volume in the containment refueling tank IRWST, the circulation time can be calculated based on the water volume in the containment refueling tank IRWST and the total circulation volume of the first circulation loop 10, the second circulation loop 20, and the third circulation loop 30.

[0031] This embodiment fills the gap in the solution for recirculation after abnormal water quality in the refueling tank inside the containment under a specific mode, solving the actual needs of nuclear power units and enabling nuclear power units to operate more safely and stably.

[0032] In some embodiments, the recirculation system following abnormal water quality in the containment refueling tank under multiple modes is referenced. Figure 3 The third circulation loop 30 in this embodiment also includes a third check valve 303, a third orifice plate 304, and a fourth orifice plate 305. The second end of the first heat exchanger 302 is connected to the first end of the third check valve 303 via a pipe. The second end of the third check valve 303 is connected to the first end of the third orifice plate 304 via a pipe. The second end of the third orifice plate 304 is connected to the second inlet of the refueling tank inside the containment via a pipe. The first end of the first heat exchanger 302 is connected to the first end of the fourth orifice plate 305 via a pipe. The second end of the fourth orifice plate 305 is connected to the second end of the first EHR pump 301 via a pipe. This embodiment improves the stability of the third circulation loop by incorporating a check valve and an orifice plate.

[0033] In some embodiments, the recirculation system following abnormal water quality in the containment refueling tank under multiple modes is referenced. Figure 3 The third circulation loop 30 in this embodiment also includes at least one electric valve 50 and at least one manual valve 60. The electric valve 50 and the manual valve 60 are installed in the third circulation loop 30, and one of the electric valves 50 is connected in parallel with the fourth throttling orifice plate 305. The electric valve 50 and the manual valve 60 can be installed as needed, for example, according to… Figure 3 Install at the location shown.

[0034] In some embodiments, the multi-mode containment refueling tank water quality abnormality recirculation system also includes a fourth circulation loop 400. The fourth circulation loop 400 includes a second EHR pump 401 and a second heat exchanger 402. The first end of the second EHR pump 401 is connected via a pipe to a second backup outlet of the containment refueling tank. The second end of the second EHR pump 401 is connected via a pipe to the first end of the second heat exchanger 402. The second end of the second heat exchanger 402 is connected via a pipe to a third inlet of the containment refueling tank. Figure 3 As can be seen from the diagram, in this embodiment, after the second backup outlet is activated, the positions of the second backup outlet and the third inlet on the refill tank inside the containment are staggered to achieve a better turbidity effect.

[0035] If the third circulation loop 30 malfunctions during the operation of the first circulation loop 10, the second circulation loop 20, and the third circulation loop 30, it will be shut down and the fourth circulation loop 400 will be started. After starting the fourth circulation loop 400, calculations show that the circulation flow rate of the first PTR purification pump 101 used in the first circulation loop 10 is 90 m³ / h, the circulation flow rate of the second PTR purification pump 201 used in the second circulation loop 20 is 90 m³ / h, and the circulation flow rate of the second EHR pump 401 used in the fourth circulation loop 400 is 200 m³ / h. Therefore, the total circulation flow rate of the first circulation loop 10, the second circulation loop 20, and the fourth circulation loop 400 is 380 m³ / h. This circulation flow rate is slightly larger than the flow rate when three rows of RIS low-pressure safety pumps are used for circulation simultaneously. It can meet the circulation requirements in modes 4, 5, and 6 and is slightly better than the existing technology that uses three rows of RIS low-pressure safety pumps for circulation simultaneously.

[0036] Furthermore, based on the circulation requirements, namely that the total circulation flow rate is at least one times the water volume in the containment refueling tank IRWST, the circulation time can be calculated based on the water volume in the containment refueling tank IRWST and the total circulation volume of the first circulation loop 10, the second circulation loop 20, and the fourth circulation loop 400.

[0037] It is understandable that, since the circulation flow rates of the third circulation loop 30 and the fourth circulation loop 400 are the same, the fourth circulation loop 400 can be started as the normal circulation loop, while the third circulation loop 30 can be used as a backup circulation loop. That is, after detecting an abnormality in the water quality in the refueling tank inside the containment vessel, the first circulation loop 10, the second circulation loop 20, and the fourth circulation loop 400 will be started simultaneously and run for a preset time. Furthermore, if the fourth circulation loop 400 malfunctions during the operation of the first circulation loop 10, the second circulation loop 20, and the fourth circulation loop 400, then the fourth circulation loop 400 will be shut down and the third circulation loop 30 will be started.

[0038] It should be noted that the third loop 30 and the fourth loop 400 in this embodiment cannot operate simultaneously. Only one of the third loop 30 and the fourth loop 400 can operate, and the other is used as a backup loop.

[0039] This embodiment is equipped with a backup circulation loop, which is activated when the normal circulation loop malfunctions, ensuring that the refueling tank inside the containment can be circulated smoothly.

[0040] In some embodiments, the fourth circulation loop 400, which operates in response to abnormal water quality in the containment refueling tank under multiple modes, further includes a fourth check valve 403, a fifth orifice plate 404, and a sixth orifice plate 405. The second end of the second heat exchanger 402 is connected to the first end of the fourth check valve 403 via a pipe. The second end of the fourth check valve 403 is connected to the first end of the fifth orifice plate 404 via a pipe. The second end of the fifth orifice plate 404 is connected to the third inlet of the containment refueling tank via a pipe. The first end of the second heat exchanger 402 is connected to the first end of the sixth orifice plate 405 via a pipe. The second end of the sixth orifice plate 405 is connected to the second end of the second EHR pump 401 via a pipe. This embodiment utilizes a check valve and an orifice plate in the fourth circulation loop to ensure more stable operation of the fourth circulation loop.

[0041] In some embodiments of the multi-mode containment refueling tank water quality abnormality recirculation system, the fourth circulation loop 400 further includes at least one electrically operated valve 50 and at least one manually operated valve 60. The at least one electrically operated valve 50 and at least one manually operated valve 60 are installed in the fourth circulation loop 400, and one of the electrically operated valves 50 is connected in parallel with the sixth orifice plate 405. The electrically operated valve 50 and the manually operated valve 60 can be installed as needed, for example, according to… Figure 3 Install at the location shown.

[0042] In some embodiments, the recirculation system following an abnormal water quality in the refueling tank within the containment in a multi-mode configuration also includes at least one RIS low-pressure safety injection pump circulation loop for circulating water in the refueling tank within the containment. The nuclear power unit includes three RIS low-pressure safety injection pump circulation loops.

[0043] In the fully unloaded mode, due to the large-scale maintenance work already underway, it is unlikely that all three RIS low-pressure safety pump circulation loops will be available simultaneously. Generally, at least one loop will be under maintenance. In this case, the RIS low-pressure safety pump circulation loop that is not under maintenance can be selected for the circulation operation. Furthermore, considering that the technical specifications do not specify the measures to be taken and the recovery time for water quality issues in the containment refueling tank IRWST during the fully unloaded mode, at least one of the following can be selected for circulation: first circulation loop 10, second circulation loop 20, third circulation loop 30, fourth circulation loop 400, and RIS low-pressure safety pump circulation loop. However, third circulation loop 30 and fourth circulation loop 400 cannot be selected simultaneously. After selecting the circulation combination, the total circulation flow rate must be at least one times the water volume in the IRWST tank. There is no limit to the circulation time, but the continuity of the circulation operation must be ensured. If an interruption occurs, circulation must be restarted with a total circulation flow rate at least one times the water volume in the containment refueling tank IRWST.

[0044] This embodiment solves the circulation scheme in the complete unloading mode, and provides a combination of multiple technical solutions. The circulation loop can be reasonably arranged according to the overhaul site conditions.

[0045] In some embodiments of the multi-mode containment refueling tank water quality abnormality recirculation system, the first circulation loop 10 further includes a first check valve 103, a first orifice plate 104, at least one manual isolation valve 40, and at least one electric valve 50. The second end of the first PTR purification pump 101 is connected to the first end of the first check valve 103 via a pipeline. The second end of the first check valve 103 is connected to the first end of the first orifice plate 104 via a pipeline. The second end of the first orifice plate 104 is connected to the first inlet of the containment refueling tank via a pipeline. At least one manual isolation valve 40 and at least one electric valve 50 are installed in the first circulation loop 10. The first check valve 103 is used to prevent backflow in the first circulation loop 10, and the first orifice plate 104 is used to control the flow rate of the first circulation loop 10. The installation of at least one manual isolation valve 40 and at least one electric valve 50 in the first circulation loop 10 can be understood as follows: the manual isolation valve 40 and the electric valve 50 can be installed as needed, for example, according to… Figure 4 The device is installed in the position shown and is required to remain open after the first circulation loop 10 is opened. This embodiment utilizes a check valve and a throttling orifice plate in the first circulation loop to ensure more stable operation of the first circulation loop.

[0046] In some embodiments of the multi-mode containment refueling tank water quality abnormality recirculation system, the second circulation loop 20 further includes a second check valve 203, a second orifice plate 204, at least one manual isolation valve 40, and at least one electric valve 50. The second end of the second PTR purification pump 201 is connected to the first end of the second check valve 203 via a pipeline. The second end of the second check valve 203 is connected to the first end of the second orifice plate 204 via a pipeline. The second end of the second orifice plate 204 is connected to the first inlet of the containment refueling tank via a pipeline. At least one manual isolation valve 40 and at least one electric valve 50 are installed in the second circulation loop 20. It is understood that the manual isolation valve 40 and the electric valve 50 can be installed as needed, for example, according to... Figure 4 The device is installed in the position shown and is required to remain open after the second circulation loop 20 is opened. This embodiment utilizes a check valve and a throttling orifice plate in the second circulation loop to ensure more stable operation of the second circulation loop.

[0047] In some embodiments of the multi-mode containment refueling tank water quality abnormality recirculation system, the first circulation loop 10 is connected to the first RCV charging pump 701. If the first RCV charging pump 701 is started during the operation of the first circulation loop 10, the first circulation loop 10 will be shut down at this time because the priority level (safety level) of the first RCV charging pump 701 is higher than the containment refueling tank recirculation.

[0048] The second circulation loop 20 is connected to the second RCV charging pump 702. If the second RCV charging pump 702 is started during the operation of the second circulation loop 20, the second circulation loop 20 will be shut down at this time because the priority level (safety level) of the second RCV charging pump 702 is higher than that of the refueling tank in the containment.

[0049] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0050] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0051] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0052] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They do not limit the scope of protection of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A recirculation system for a multi-mode containment refueling tank after water quality abnormalities, characterized in that, It includes a first loop (10), a second loop (20) and a third loop (30); The first circulation loop (10) includes a first PTR purification pump (101) and a first PTR inlet valve (102). The first end of the first PTR purification pump (101) is connected to the first end of the first PTR inlet valve (102) through a pipe. The second end of the first PTR inlet valve (102) is connected to the first outlet of the refueling tank inside the containment through a pipe. The second end of the first PTR purification pump (101) is connected to the first inlet of the refueling tank inside the containment through a pipe. The second circulation loop (20) includes a second PTR purification pump (201) and a second PTR inlet valve (202). The first end of the second PTR purification pump (201) is connected to the first end of the second PTR inlet valve (202) through a pipe. The second end of the second PTR inlet valve (202) is connected to the second outlet of the refueling tank inside the containment through a pipe. The second end of the second PTR purification pump (201) is connected to the first inlet of the refueling tank inside the containment through a pipe. The third circulation loop (30) includes a first EHR pump (301) and a first heat exchanger (302). The first end of the first EHR pump (301) is connected to the first spare outlet of the refueling tank inside the containment via a pipe. The second end of the first EHR pump (301) is connected to the first end of the first heat exchanger (302) via a pipe. The second end of the first heat exchanger (302) is connected to the second inlet of the refueling tank inside the containment via a pipe. After detecting an abnormal water quality in the refueling tank inside the containment vessel, the first circulation loop (10), the second circulation loop (20), and the third circulation loop (30) are simultaneously started and run for a preset time.

2. The recirculation system for abnormal water quality in the containment refueling tank under multiple modes as described in claim 1, characterized in that, The third circulation loop (30) also includes a third check valve (303), a third orifice plate (304), and a fourth orifice plate (305). The second end of the first heat exchanger (302) is connected to the first end of the third check valve (303) via a pipe. The second end of the third check valve (303) is connected to the first end of the third orifice plate (304) via a pipe. The second end of the third orifice plate (304) is connected to the second inlet of the refueling tank inside the containment via a pipe. The first end of the first heat exchanger (302) is connected to the first end of the fourth orifice plate (305) via a pipe. The second end of the fourth orifice plate (305) is connected to the second end of the first EHR pump (301) via a pipe.

3. The recirculation system for abnormal water quality in the containment refueling tank under multiple modes as described in claim 2, characterized in that, The third circulation loop (30) further includes at least one electric valve (50) and at least one manual valve (60), the at least one electric valve (50) and at least one manual valve (60) being installed in the third circulation loop (30), and one of the electric valves (50) being connected in parallel with the fourth throttling orifice plate (305).

4. The recirculation system for abnormal water quality in the containment refueling tank under multiple modes as described in claim 1, characterized in that, It also includes a fourth circulation loop (400), which includes a second EHR pump (401) and a second heat exchanger (402). The first end of the second EHR pump (401) is connected to the second spare outlet of the refueling tank inside the containment via a pipe, the second end of the second EHR pump (401) is connected to the first end of the second heat exchanger (402) via a pipe, and the second end of the second heat exchanger (402) is connected to the third inlet of the refueling tank inside the containment via a pipe. If the third loop (30) malfunctions during operation, the third loop (30) will be shut down and the fourth loop (400) will be started.

5. The recirculation system for abnormal water quality in the containment refueling tank under multiple modes as described in claim 4, characterized in that, The fourth circulation loop (400) also includes a fourth check valve (403), a fifth orifice plate (404), and a sixth orifice plate (405). The second end of the second heat exchanger (402) is connected to the first end of the fourth check valve (403) via a pipe. The second end of the fourth check valve (403) is connected to the first end of the fifth orifice plate (404) via a pipe. The second end of the fifth orifice plate (404) is connected to the third inlet of the refueling tank inside the containment via a pipe. The first end of the second heat exchanger (402) is connected to the first end of the sixth orifice plate (405) via a pipe. The second end of the sixth orifice plate (405) is connected to the second end of the second EHR pump (401) via a pipe.

6. The recirculation system for abnormal water quality in the containment refueling tank under multiple modes as described in claim 5, characterized in that, The fourth circulation loop (400) further includes at least one electric valve (50) and at least one manual valve (60), the at least one electric valve (50) and at least one manual valve (60) being installed in the fourth circulation loop (400), and one of the electric valves (50) being connected in parallel with the sixth throttling orifice plate (405).

7. The recirculation system for abnormal water quality in the containment refueling tank under multiple modes as described in claim 1, characterized in that, It also includes at least one RIS low-pressure safety pump circulation loop for water circulation in the refueling tank within the containment. In the fully unloading mode, at least one of the first circulation loop (10), the second circulation loop (20), the third circulation loop (30), and the RIS low-pressure injection pump circulation loop is selected for circulation operation.

8. The recirculation system for abnormal water quality in the containment refueling tank under multiple modes as described in claim 1, characterized in that, The first circulation loop (10) also includes a first check valve (103), a first throttling orifice plate (104), at least one manual isolation valve (40) and at least one electric valve (50). The second end of the first PTR purification pump (101) is connected to the first end of the first check valve (103) through a pipeline. The second end of the first check valve (103) is connected to the first end of the first orifice plate (104) through a pipeline. The second end of the first orifice plate (104) is connected to the first inlet of the refill water tank inside the containment through a pipeline. The at least one manual isolation valve (40) and the at least one electric valve (50) are installed in the first circulation loop (10).

9. The recirculation system for abnormal water quality in the containment refueling tank under multiple modes as described in claim 1, characterized in that, The second circulation loop (20) also includes a second check valve (203), a second throttling orifice plate (204), at least one manual isolation valve (40) and at least one electric valve (50). The second end of the second PTR purification pump (201) is connected to the first end of the second check valve (203) through a pipeline. The second end of the second check valve (203) is connected to the first end of the second orifice plate (204) through a pipeline. The second end of the second orifice plate (204) is connected to the first inlet of the refill water tank inside the containment through a pipeline. The at least one manual isolation valve (40) and the at least one electric valve (50) are installed in the second circulation loop (20).

10. The recirculation system for abnormal water quality in the containment refueling tank under multiple modes as described in claim 1, characterized in that, The first circulation loop (10) is connected to the first RCV charging pump (701). If the first RCV charging pump (701) is started during the operation of the first circulation loop (10), the first circulation loop (10) is shut down. The second circulation loop (20) is connected to the second RCV charging pump (702). If the second RCV charging pump (702) is started during the operation of the second circulation loop (20), the second circulation loop (20) is shut down.

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