Temporary cold source system and method for realizing cold state function test of nuclear power plant

Abstract

The embodiment of the invention provides a temporary cold source system and a method for realizing a cold state function test of a nuclear power plant, and the temporary cold source system comprises a temporary cooling water supply module which is used for providing cooling water in a single system debugging stage before the cold test; the containment ventilation and refrigeration module is used for carrying out dehumidification and refrigeration on the interior of the containment before the containment tightness test; the main pump motor test cooling module is used for executing a main pump motor test before a cold test; and the cold-state function test cooling module is used for realizing heat export and cooling of the cold-state function test of the nuclear power plant. The temporary cold source system and the method for realizing the cold-state function test of the nuclear power plant provided by the embodiment of the invention can effectively solve the problem that the cold-state function test of the nuclear power plant is limited by debugging of an important service water system (SEC), and can ensure that major project nodes are realized on schedule. The device has the characteristics of high reliability, low test cost and no restriction by external maritime work conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power plant commissioning, and particularly to a temporary cold source system and a method for realizing the cold state function test of a nuclear power plant. Background Art

[0002] During the construction of a nuclear power plant, it is necessary for the important service water system (SEC system) to be officially available to perform the cold state function test of the nuclear power plant. However, the important service water system (SEC) often cannot be realized on schedule due to the long approval cycle for the application of using seawater, and the large construction workload of the combined pump house, intake channel, drainage corridor, siphon well and submarine tunnel.

[0003] In the prior art, various high-cost means must be adopted to make the important service water system (SEC) available for commissioning before the cold state function test can be carried out, including digging a temporary drainage pipe gallery to discharge into the sea to solve the problem that the formal siphon well or submarine tunnel is unavailable, or installing large pumps to draw water from other places, closing the forebay, and establishing an SEC self-circulation to solve the problem of the restriction of the seawater use application and the unavailability of external water intake. At present, there is no commissioning plan that can carry out the cold state function test of a nuclear power plant without the SEC system being available. Moreover, in the prior art, in order to make the SEC system available for commissioning, a large number of temporary measures are required, with high input costs and high test risks. Summary of the Invention

[0004] Embodiments of the present invention provide a temporary cold source system and a method for realizing the cold state function test of a nuclear power plant, aiming to solve the problem that the existing cold state function test of a nuclear power plant is restricted by the availability of the important service water system (SEC) and cannot achieve major project nodes on schedule.

[0005] In a first aspect, embodiments of the present invention provide a temporary cold source system for the cold state function test of a nuclear power plant, including:

[0006] A temporary cooling water supply module for providing cooling water during the single-system commissioning stage before the cold test;

[0007] A containment ventilation and refrigeration module for dehumidifying and refrigerating the inside of the containment before the containment tightness test;

[0008] A main pump motor test cooling module for performing a main pump motor test before the cold test to control the water temperature of the equipment cooling water system not to exceed the safety setting value;

[0009] A cold state function test cooling module for realizing heat extraction and cooling of the cold state function test of the nuclear power plant.

[0010] In a second aspect, embodiments of the present invention provide a method for realizing the cold state function test of a nuclear power plant, including:

[0011] Use the temporary cooling water supply module to provide cooling water during the single-system commissioning stage before the cold test;

[0012] Use the containment ventilation and refrigeration module to dehumidify and refrigerate the inside of the containment before the containment tightness test;

[0013] Use the main pump motor test cooling module to perform the main pump motor test before the cold test to control the water temperature of the equipment cooling water system not to exceed the safety set value;

[0014] Use the cold functional test cooling module to achieve heat extraction and cooling for the cold functional test of the nuclear power plant.

[0015] The embodiment of the present invention provides a temporary cold source system and a method for realizing the cold functional test of a nuclear power plant. The temporary cold source system includes a temporary cooling water supply module, a containment ventilation and refrigeration module, a main pump motor test cooling module, and a cold functional test cooling module. The temporary cooling water supply module and the containment ventilation and refrigeration module are used to commission each system equipment before the test to ensure that each system equipment can operate normally, so that when the main pump motor test cooling module and the cold functional test cooling module conduct tests, the test process will not be affected due to the lack of a cold source. If there is a lack of a formal cold source, the temporary cooling water supply module can be used to provide cooling water for the single system. This temporary measure has a relatively low risk. Brief Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a module schematic diagram of a temporary cold source system for the cold functional test of a nuclear power plant provided by the embodiment of the present invention;

[0018] Figure 2 It is a connection schematic diagram of the temporary cooling water supply module and the single system;

[0019] Figure 3 It is a component schematic diagram of the containment ventilation and refrigeration module;

[0020] Figure 4 It is a connection schematic diagram of the cold functional test module and each system;

[0021] Figure 5 It is a process schematic diagram of a method for realizing the cold functional test of a nuclear power plant provided by the embodiment of the present invention;

[0022] Figure 6Schematic diagram of a sub - process for a method of realizing cold - state functional tests in a nuclear power plant provided by an embodiment of the present invention;

[0023] Figure 7 Another schematic diagram of a sub - process for a method of realizing cold - state functional tests in a nuclear power plant provided by an embodiment of the present invention;

[0024] Figure 8 Another schematic diagram of a sub - process for a method of realizing cold - state functional tests in a nuclear power plant provided by an embodiment of the present invention;

[0025] Figure 9 Another schematic diagram of a sub - process for a method of realizing cold - state functional tests in a nuclear power plant provided by an embodiment of the present invention;

[0026] Figure 10 Schematic diagram of the cooling scheme for the RIS - RHR heat exchanger in Train A;

[0027] Figure 11 Schematic diagram of the cooling scheme for the RIS - RHR heat exchanger in Train B;

[0028] Figure 12 Schematic diagram of the cooling scheme for the RIS - RHR heat exchanger in Train C;

[0029] Figure 13 Schematic diagram of the parameters for EHR to reversely cool RRI.

[0030] Explanation of the markings in the figure:

[0031] 1. Temporary cold source system;

[0032] 11. Temporary cooling water supply module;

[0033] 12. Containment ventilation and refrigeration module; 121. Main air supply subsystem; 1211. Fan; 122. Special air - cooled unit; 1221. Chilled water pump; 123. Temporary refrigeration unit; 1231. Temporary refrigerator; 1232. Circulation pump; 124. EVR heat exchanger; 1241. Cooling coil;

[0034] 13. Main pump motor test cooling module;

[0035] 14. Cold - state functional test cooling module; 141. Primary circuit cooling module; 1411. RIS - RHR heat exchanger; 1412. PTR heat exchanger; 142. Equipment cooling water circulation loop cooling module; 1421. IRWST pool;

[0036] 15. Single system; 151. Safety injection system; 152. Containment heat removal system; 1521. Containment heat exchanger; 153. Equipment cooling water system; 154. Chemical and volume control system;

[0037] 16. Additional cooling system; 161. Intermediate circuit. Detailed implementation manner

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] It should be understood that when used in this specification and the appended claims, the terms "comprises" and "comprising" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0040] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in this specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0041] It should be further understood that the term " / and / " used in this specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0042] Please refer to Figure 1-2 , an embodiment of the present invention provides a temporary cold source system 1 for cold functional tests of nuclear power plants, including:

[0043] A temporary cooling water supply module 11 for providing cooling water during the commissioning stage of a single system 15 before the cold test;

[0044] A containment ventilation and refrigeration module 12 for dehumidifying and refrigerating the inside of the containment before the containment tightness test;

[0045] A main pump motor test cooling module 13 for performing a main pump motor test before the cold test to control the water temperature of the equipment cooling water system not to exceed the safety set value;

[0046] A cold functional test cooling module 14 for realizing heat extraction and cooling of the cold functional test of the nuclear power plant.

[0047] In this embodiment, before the test, each system device is cooled and debugged by the temporary cooling water supply module 11 and the containment ventilation and refrigeration module 12 to ensure the normal operation of each system device. When the main pump motor test cooling module 13 conducts the test, the test process will not be affected due to the lack of a cold source. If there is no formal cold source, the temporary cooling water supply module can provide cooling water for a single system. After the temporary cooling water supply module 11, the containment ventilation and refrigeration module 12, and the main pump motor test cooling module 13 are completed, the cold state functional test cooling module 14 is then executed. Since a large amount of heat needs to be exported during the cold state functional test of the nuclear power plant by the cold state functional test cooling module 14, the exported heat needs to be cooled. For a single system 15, cooling water needs to be provided by the temporary cooling water supply module 11 during the commissioning phase. The temporary cooling water supply module 11 includes a temporary demineralized water storage and distribution system (abbreviated as SED), and cooling water is provided through the SED to complete the first start-up test of the motor and pump in the single system 15. For the containment, before the containment tightness test (abbreviated as CTT), the inside of the containment needs to be dehumidified and refrigerated by the containment ventilation and refrigeration module 12. During the dehumidification and refrigeration process, the required cooling water flow rate is 168.6 m 3 / h, the heat load is 1080 kW, and refrigeration needs to be continuously provided for 2 - 3 days. For the main pump motor, during the test, the water inventory in the circulation loop of the component cooling water system 153 (abbreviated as RRI) needs to be maintained at a predetermined level, and this predetermined level can be set to the maximum water inventory, such as 357 m 3 . Then, directly start the RRI to circulate, and conduct a single main pump motor test while controlling the water temperature in the circulation loop not to exceed the safety set value (such as 38°C).

[0048] Specifically, as Figure 2 shown, the temporary cooling water supply module 11 is connected to the single system 15 through a temporary water supply network and is used to provide cooling water to the single system 15 to complete the first start-up test. The single system 15 includes a safety injection system 151, a containment heat removal system 152, a component cooling water system 153, and a chemical and volume control system 154.

[0049] In this embodiment, the temporary water supply network is the temporary water supply network of the SED, which mainly completes the first start-up test of the motor and pump in the single system 15. The single system 15 includes a safety injection system (RIS) 141, a containment heat removal system (EHR) 142, a component cooling water system (RRI) 143, and a chemical and volume control system (RCV) 144. During the test, the water consumption of each system is shown in Table 1:

[0050] Table 1. Cooling water requirements of each system during the single system test phase

[0051]

[0052]

[0053] In specific implementation, SED also includes temporary water supply devices with a maximum water supply capacity of up to 160m 3 / h, and the water storage capacity of its water tank is 1600m 3 , water production capacity is 60m 3 / h, which can meet the cooling water demand for the initial startup test of the motors and pumps of RIS, EHR, RRI, and RCV.

[0054] Specifically, such as Figure 3 As shown, the containment ventilation and refrigeration module 12 includes a containment cooling and ventilation system having a main air supply subsystem 121 and a dedicated air cooling unit 122 or a temporary refrigeration unit 123 for providing cooling water to the main air supply subsystem 121 .

[0055] In this embodiment, during the ventilation and cooling stage before the containment sealing test (CTT), the main air supply subsystem 121 of the containment cooling ventilation system (EVR) is required to dehumidify and cool the interior of the containment. During the dehumidification and cooling process, the cooling water flow rate required by the EVR is 168.6m 3 / h, the total heat load is 1080kW, and cooling needs to be provided continuously for 2-3 days.

[0056] In specific implementation, a dedicated air cooling unit 122 of a safety cooling water system (DEL) can be used to provide cooling water, which can provide a cooling water flow of 240m 3 / h, the cooling water flow rate has met the cooling water flow rate required in the dehumidification and refrigeration process (168.6m 3 / h), the cooling capacity of the dedicated air cooling unit 122 is 1260kW, which is greater than the total heat load generated, so that the temperature inside the containment is reduced. A temporary refrigeration unit 123 can also be used to provide cooling water to the EVR, wherein the cooling capacity provided by a single temporary refrigeration unit 123 is 420kW and the cooling water flow rate is 100m 3 / h, if the cooling water flow required by the EVR during the dehumidification and cooling process is met, three temporary refrigeration units 123 are required to provide cooling water for the EVR.

[0057] Specifically, such as Figure 3 As shown, the main air supply subsystem 121 includes a fan 1211, which is connected to a ring header and a distribution pipe network in sequence. The fan 1211 is used to cool the inhaled air and send it into the ring header, and then transport it to the target area through the distribution pipe network.

[0058] In this embodiment, during the dehumidification and refrigeration process, the cooling water flow required by the EVR is 168.6 m 3 / h, and the total heat load is 1080 kW. In order to better cool the inhaled air, two fans 1211 need to operate simultaneously. Each fan 1211 transports the refrigerated air to the target area through an annular header and a distribution pipe network. In specific implementation, four fans 1211 are provided in the main air supply subsystem 121. When the system is operating normally, two of the fans 1211 are put into operation, and the other two fans 1211 are in standby state. When the two fans 1211 in use cannot be used due to other elements, the other two fans 1211 are used, thus successfully completing the dehumidification and refrigeration inside the containment. In addition, the fans 1211 can be replaced with air-conditioning units, and the same effect can be achieved.

[0059] In specific implementation, the operating chilled water system (DER) provides cooling water. Among them, the supply and return water temperatures of this system are 7 - 12 °C. Condensate will be generated after the cooling water passes through the fans 1211, and these condensates are discharged through the nuclear island exhaust and water delivery system (RPE).

[0060] Specifically, as Figure 3 shown, the main air supply subsystem 121 further includes an EVR heat exchanger 124 having a cooling coil 1241; the dedicated air-cooled unit 122 is provided with a chilled water pump 1221 for transporting cooling water, and the dedicated air-cooled unit 122 is connected to the cooling coil 1241 of the EVR heat exchanger 124 through a temporary pipeline and an in-island pipeline;

[0061] Alternatively, the temporary refrigeration unit 123 includes a temporary refrigerator 1231 and a circulation pump 1232. The temporary refrigerator 1231 is used to provide cooling water, and the circulation pump 1232 is used to transport the cooling water provided by the temporary refrigerator 1231. The temporary refrigerator 1231 is connected to the cooling coil 1241 of the EVR heat exchanger 124 through a temporary pipeline and an in-island pipeline.

[0062] In this embodiment, when the dedicated air-cooled unit 122 of DEL is used to provide chilled water, the chilled water provided by the dedicated air-cooled unit 122 is led from Room A to Room B through a temporary pipeline (a temporary pipeline with a size of DN200 can be used), and the temporary pipeline is connected to the in-island pipeline of the DER, and then the in-island pipeline is connected to the cooling coil 1241 of the EVR heat exchanger 124. In specific implementation, the dedicated air-cooled unit 122 includes a chilled water pump 1221 for transporting cooling water, and its rated flow rate is 240 m 3 / h, and the head is 38 meters (the minimum flow rate is 168 m 3 / h, and the maximum flow rate is 288 m 3 / h, after bypassing through the pipeline with the minimum flow rate, the chilled water flow rate sent out is 217.3 m 3 / h).

[0063] In specific implementation, if the fan 1211 is replaced with an air conditioning unit, four air conditioning units are also required. The elevation of the four air conditioning units is 33.2 meters, and the elevation of the chilled water pump 1221 is 26.3 meters. The height difference between the two is 6.9 meters. The head of the chilled water pump 1221 (i.e., 38 meters) minus the height difference (i.e., 6.9) is 31.1 meters (used to offset the frictional resistance along the pipeline). The elevation of the pump for operating the chilled water system (hereinafter referred to as the DER pump) is -3.45 meters, and the height difference from the four air conditioning units is 36.65 meters. The head of the DER pump is 61 meters, so the head of the DER pump minus the height difference between the two is 24.35 meters.

[0064] For the DN200 pipeline, with a flow velocity of 168.6 m 3 / h, supplying chilled water at 7 - 12°C, the specific resistance (ΔP m ) is 111.3867669 Pa / m, calculated according to the following formula:

[0065]

[0066] where λ is the friction resistance coefficient, l is the straight pipe section length (m), ρ is the density of water (kg / m 3 ), for a system supplying water at 7 - 12°C, the average temperature is taken as 10°C, and the density of water is taken as 999.73 kg / m 3 , ν is the flow velocity of water (m / s), and d is the pipeline diameter (m).

[0067] The local resistance of a 90° elbow is 563.0891652 Pa, and the local resistance of a 45° elbow is 287.0650646 Pa, which can be calculated according to the following formula:

[0068]

[0069] where ζ is the local resistance coefficient of the pipeline fitting, ν is the flow velocity of water (m / s), ρ is the density of water (kg / m 3 ), taken as 999.73 kg / m 3 . The values of the local resistance coefficient ζ of common pipeline fittings are shown in Table 2 as follows:

[0070] Table 2. Local resistance coefficients of common pipeline fittings

[0071]

[0072] Based on this estimation, the resistance loss of the newly added temporary pipeline is 53276.11658 Pa, the self-resistance loss of the DEL formal loop is 163956 Pa, the resistance loss of the DER inlet pipeline to the island is 71579 Pa, the resistance loss of the coil in the EVR heat exchanger is 50000 Pa, and the resistance loss of the entire cooling supply loop is 338811.1166 Pa. Converted to head resistance, it is 33.4380574 meters. The head of the chilled water pump of the DEL dedicated air-cooled unit is 38 meters. It can be seen that it is feasible to use a DN200 temporary pipeline to connect the DER inlet pipeline to the island to supply chilled water to the air-conditioning unit.

[0073] When using the temporary refrigeration unit 123 to supply cooling water, the temporary refrigeration unit 123 can be installed at a suitable location (such as outside the door) to supply chilled water to the main air supply subsystem 121. Among them, the temporary refrigeration unit 123 includes a temporary refrigerating machine 1231 and a circulation pump 1232. The heat exchange capacity of the temporary refrigerating machine 1231 used is 420 kW, the total power consumption is 123 kW, and the performance coefficient is 3.41. Therefore, in order to effectively handle the total heat load (1080 kW) during the dehumidification and refrigeration process, three identical temporary refrigerating machines 1231 need to be installed. The flow rate of the circulation pump 1232 is 100 m 3 / h. In order to meet the cooling water flow rate required by the EVR (168.6 m 3 / h) during the dehumidification and refrigeration process, two circulation pumps 1232 need to be installed.

[0074] In specific implementation, the temporary refrigeration unit 123 also includes a temporary chilled water circulation loop. The temporary chilled water supply loop is an integrated unit, including a expansion tank, a liquid level switch, a pre-pump filter, a circulation pump, a flow switch, a pressure gauge, a thermometer, an auxiliary electric heater, an automatic air vent, an exhaust pipe, a hose joint, a power supply interface, and corresponding control circuits and other structures. Therefore, the head of the circulation pump 1232 needs to meet the flow resistance requirements of the connected temporary chilled water circulation loop and can be selected as 60 meters.

[0075] Specifically, as Figure 4 shown, the cold-state function test cooling module 14 includes a primary loop cooling module 141 and a equipment cooling water circulation loop cooling module 142. The primary loop cooling module 141 is used to cool the primary loop heat load of the equipment cooling water system 153, and the equipment cooling water circulation loop cooling module 142 is used to cool the remaining heat load of the circulation loop of the equipment cooling water system 153.

[0076] In this embodiment, the heat load generated during the cold-state functional test can be divided into two parts, namely the primary loop heat load of the equipment cooling water system 153 and the remaining heat load of the circulation loop. Different cooling methods are adopted for these two parts of the heat load. Among them, the primary loop heat load is cooled by the primary loop cooling module 141, and the remaining heat load of the circulation loop is cooled by the equipment cooling water circulation loop cooling module 142, so as to ensure the normal operation of the main pump motor test.

[0077] Specifically, as Figure 4 shown, the temporary cold source system 1 further includes an additional cooling system 16. The primary loop cooling module 141 includes a RIS-RHR heat exchanger 1411 and a PTR heat exchanger 1412 connected to the RIS-RHR heat exchanger 1411. Both the RIS-RHR heat exchanger 1411 and the PTR heat exchanger 1412 include an A column, a B column, and a C column. The RIS-RHR heat exchanger 1411 is connected to the intermediate loop 161 of the additional cooling system 16.

[0078] In this embodiment, the intermediate loop 161 of the additional cooling system 16 (abbreviated as ECS) is connected to the RIS-RHR heat exchanger 1411, so that when the primary loop cooling module 141 cools the primary loop heat load, a total of three columns of RIS-RHR heat exchangers 1411 (namely the A-column RIS-RHR heat exchanger, the B-column RIS-RHR heat exchanger, and the C-column RIS-RHR heat exchanger) are used for cooling. This cooling method can be summarized as three RIS-RHR heat exchangers + ECS intermediate loop cooling. If any one column of the RIS-RHR heat exchanger 1411 fails, it will automatically switch to the other two columns of the RIS-RHR heat exchanger 1411 to continue cooling the primary loop. The two failed columns still have the cooling capacity for the primary loop as long as the ECS cold source is available. Specifically, during implementation, since the RIS-RHR heat exchanger 1411 is connected to the PTR heat exchanger 1412, and the PTR heat exchanger 1412 also includes three columns of PTR heat exchangers (namely the A-column PTR heat exchanger, the B-column PTR heat exchanger, and the C-column PTR heat exchanger), during the cooling process, the cooling water passing through the RIS-RHR heat exchanger 1411 will enter the PTR heat exchanger 1412 and then cool the primary loop heat load.

[0079] It should be noted that if the ECS cold source fails, since the main pump motor, the RIS motor, the RCV motor, and the RCV letdown heat exchanger are all supplied with cooling water by the equipment cooling water system 153 (RRI), at this time, the main pump motor test cooling module 13 can be directly stopped, and the primary loop will not heat up rapidly, that is, the primary loop heat load will not increase, and the unit state is still controllable.

[0080] Specifically, the primary loop heat load is the heat load generated by circulating one main pump, three RIS pumps, and an RCV pump minus the heat load generated by the RCV letdown heat exchanger. Alternatively, the primary loop heat load is the heat load generated by circulating three main pumps, three RIS pumps, and an RCV pump minus the heat load generated by the RCV letdown heat exchanger.

[0081] In this embodiment, there are two calculation methods for the primary loop heat load. The first is the heat load generated by circulating one main pump, three RIS pumps, and an RCV pump minus the heat load of the RCV letdown heat exchanger, and its result during the test is equal to 5.7764953 MW. The second is the heat load generated by circulating three main pumps, three RIS pumps, and an RCV pump minus the heat load generated by the RCV letdown heat exchanger, and its result during the test is equal to 16.7899159 MW. If 3 - row RIS - RHR heat exchangers are used to cool the intermediate loop of the ECS, the total heat - carrying capacity is 18.93 MW.

[0082] Specifically, as Figure 4 shown, the equipment cooling water circulation loop cooling module 142 includes the IRWST pool 1421, the containment heat removal system 152 includes the containment heat exchanger 1521, and the IRWST pool 1421 is connected to the containment heat exchanger 1521; the main pump motor test cooling module 13 is connected to the IRWST pool 1421.

[0083] In this embodiment, connecting the IRWST pool 1421 to the containment heat exchanger enables the equipment cooling water circulation loop cooling module 142 to use the containment heat removal system 152 (abbreviation: EHR) to reversely cool the equipment cooling water system (abbreviation: RRI) when cooling the heat load of the circulation loop. This cooling method can be summarized as EHR reversely cooling RRI, and it cools by transferring heat to the IRWST pool 1421. The IRWST pool 1421 takes away the heat through online water replacement. Among them, the heat - carrying capacity of the containment heat exchanger 1521 is 9.2 MW. When the main pump motor test cooling module 13 is connected to the IRWST pool 1421, the temperature of the RRI is maintained stable through online water replacement (that is, while replenishing water and draining water), that is, controlling the water temperature of the equipment cooling water system not to exceed the safety set value.

[0084] Specifically, the remaining heat load of the circulation loop is the sum of the heat loads generated by the main pump motor, RIS motor, RCV letdown heat exchanger, RCV motor, self - circulation of the circulation loop, and the heat load of the motors of the equipment cooling water system 153.

[0085] In this embodiment, the remaining heat load of the circulation loop is equal to 4.5100841 MW. During specific implementation, by using EHR to reversely cool RRI, the heat loads of three main pump motors, RIS motors, RCV letdown heat exchangers, RCV motors, and the self-circulation of the circulation loop can be removed, with a total of 3.888 MW. If the RIS motor and the RCV letdown heat exchanger are directly cooled by connecting to temporary SED water, the heat load that needs to be removed by reverse cooling is 2.828 MW.

[0086] By adopting the temporary cold source system 1 provided in the embodiment of the present invention, the heat export requirement for cold commissioning can be met, and it is not restricted by the application for using seawater. The amount of seawater operation is small, which can effectively solve the problem of complex cold functional tests in the prior art. Moreover, the temporary cold source system in this embodiment does not need to wait for the formal cold source to be available all the time, and can also ensure the realization of project nodes on schedule.

[0087] As Figure 5 shown, the embodiment of the present invention also provides a method for realizing the cold functional test of a nuclear power plant, which is applied to the aforementioned temporary cold source system and includes S10 - S40:

[0088] S10. Use the temporary cooling water supply module to provide cooling water during the single-system commissioning stage before cold commissioning;

[0089] S20. Use the containment ventilation and refrigeration module to dehumidify and refrigerate the inside of the containment before the containment tightness test;

[0090] S30. Use the main pump motor test cooling module to perform the main pump motor test before cold commissioning to control the water temperature of the equipment cooling water system not to exceed the safety set value;

[0091] S40. Use the cold functional test cooling module to realize the heat export and cooling of the cold functional test of the nuclear power plant.

[0092] In S10, during the single-system commissioning stage before cold commissioning, the temporary cooling water supply module can be used to provide cooling water because the single systems in a nuclear power plant need appropriate cooling conditions during commissioning to simulate the temperature environment during normal operation, so as to accurately test the performance and functions of each single system, ensure that it can work properly under normal temperature conditions, and avoid component damage or performance anomalies caused by excessive temperature. For example, for some temperature-sensitive devices such as motors and sensors, appropriate cooling can ensure that they do not fail due to overheating during the test, so that potential problems of the devices can be accurately found, improving the accuracy and reliability of the commissioning. The temporary cooling water supply module can provide an independent cooling source according to the commissioning requirements of the single system, enabling the single system to be commissioned without being restricted by the overall cooling water system of the nuclear power plant, shortening the commissioning time, and improving the progress of the construction and commissioning of the entire nuclear power plant.

[0093] In S20, before the containment integrity test, it is necessary to control the temperature and humidity inside the containment. By using the containment ventilation and refrigeration module to dehumidify and refrigerate the inside, an ideal environment can be created for the containment integrity test. If the humidity inside the containment is high, it may affect the sealing performance of the sealing material, resulting in inaccurate test results. Through dehumidification and refrigeration, the sealing material can be in the best test state, ensuring the accuracy and reliability of the integrity test.

[0094] In S30, the main pump motor generates heat during operation. If the water temperature is too high, it may affect the performance and lifespan of the motor. Therefore, when the water volume in the circulation loop of the equipment cooling water system reaches a predetermined value, the main pump motor test cooling module needs to be started to circulate water, so as to control the water temperature in the circulation loop not to exceed the predetermined water temperature, ensuring that the main pump motor operates within a stable temperature range, avoiding problems such as a decrease in the insulation performance and efficiency of the motor caused by overheating, and guaranteeing the accuracy of the motor performance test.

[0095] In S40, during the performance of the cold functional test of the nuclear power plant, since a large amount of heat is exported, the heat is split into two parts for cooling. One part is cooled by the additional cooling system, and is taken away through the pipelines of the RRI system and the RIS-RHR heat exchanger; the other part is cooled by the containment heat export system, reversely cooling the RRI, and taking the heat to the IRWST pool.

[0096] In this embodiment, four modules (temporary cooling water supply module, containment ventilation and refrigeration module, main pump motor test cooling module, and cold functional test cooling module) are each responsible for the cooling and temperature and humidity control tasks in different stages and different parts, and are started and closed according to different test stages and requirements, improving the flexibility and operability of the entire test system. For example, after the single-system commissioning is completed, the temporary cooling water supply module can be closed without affecting the normal operation of other modules. When a local problem occurs in a certain module, only the corresponding module needs to be maintained and adjusted, without having too much impact on the entire cold source system, reducing the maintenance cost and time cost.

[0097] As Figure 6 shown, the method for implementing the cold functional test of the nuclear power plant includes S51 - S52:

[0098] S51. Introduce the cooling water of the additional cooling system into the A-column RIS-RHR heat exchanger through a temporary pipeline;

[0099] S52. Lead the failure signal of the A-column RIS-RHR heat exchanger to the first protection shutdown instruction. If the cooling of the A-column RIS-RHR heat exchanger fails, close the A-column RIS-RHR heat exchanger, and lead the cooling water of the additional cooling system to the B-column RIS-RHR heat exchanger and the C-column RIS-RHR heat exchanger through the cooling side pipeline of the A-column PTR heat exchanger.

[0100] In this step, the A-column RIS-RHR heat exchanger is mainly used for cooling with the additional cooling system (ESC). A first valve that can be opened and closed is provided between the A-column RIS-RHR heat exchanger and the additional cooling system. When the cooling of the A-column RIS-RHR heat exchanger fails, a failure signal will be sent. The temporary cold source system leads the failure signal to the first protection shutdown instruction and controls the first valve to close to close the A-column RIS-RHR heat exchanger. All the cooling water that originally flowed through this part will flow through the other two columns (the B-column RIS-RHR heat exchanger and the C-column RIS-RHR heat exchanger), so as to ensure that the primary circuit can still be cooled by the other two columns of RIS-RHR heat exchangers in the case of the cooling failure of the A-column RIS-RHR heat exchanger. Among them, the cooling schematic diagram of the A-column RIS-RHR heat exchanger is shown in Figure 10.

[0101] As Figure 7 shown, the method for realizing the cold state functional test of the nuclear power plant further includes S61 - S62:

[0102] S61. Lead the cooling water of the additional cooling system to the B-column RIS-RHR heat exchanger through the cooling side pipeline and the temporary pipeline of the A-column PTR heat exchanger;

[0103] S62. Lead the failure signal of the B-column RIS-RHR heat exchanger to the second protection shutdown instruction. If the cooling of the B-column RIS-RHR heat exchanger fails, close the B-column RIS-RHR heat exchanger, and lead the cooling water of the additional cooling system to the A-column RIS-RHR heat exchanger and the C-column RIS-RHR heat exchanger through the B-column PTR heat exchanger.

[0104] This step is for the case of leading to the RIS-RHR heat exchanger in Train B. A second valve that can be opened and closed is provided between the PTR heat exchanger in Train A and the RIS-RHR heat exchanger in Train B. When the cooling of the RIS-RHR heat exchanger in Train B fails, a failure signal will be sent. The temporary cold source system leads the failure signal to the second protection shutdown instruction and controls the second valve to close, so as to close the RIS-RHR heat exchanger in Train B. The cooling water that originally flowed through this part will all flow through the other two trains (the RIS-RHR heat exchanger in Train A and the RIS-RHR heat exchanger in Train C), thus ensuring that when the cooling of the RIS-RHR heat exchanger in Train B fails, the primary circuit can still be cooled continuously through the other two trains of RIS-RHR heat exchangers. It should be noted that although it is led to the RIS-RHR heat exchanger in Train B only after the cooling of the RIS-RHR heat exchanger in Train A fails, the RIS-RHR heat exchanger in Train A is still available. Therefore, when the cooling of the RIS-RHR heat exchanger in Train B fails, it can still be led to the RIS-RHR heat exchanger in Train A for cooling. Among them, the cooling schematic diagram of the RIS-RHR heat exchanger in Train B is shown in Figure 11.

[0105] As Figure 8 shown, the method for realizing the cold state functional test of a nuclear power plant further includes S71 - S73:

[0106] S71: Guide the cooling water of the additional cooling system from the cooling side of the PTR heat exchanger in Train A to the cooling side of the PTR heat exchanger in Train C, and lead it to the RIS-RHR heat exchanger in Train C through a temporary pipeline;

[0107] S72: Remove the temporary bypass of the PTR heat exchanger in Train C and install a blind plate;

[0108] S73: Lead the failure signal of the RIS-RHR heat exchanger in Train C to the third protection shutdown instruction. If the cooling of the RIS-RHR heat exchanger in Train C fails, close the RIS-RHR heat exchanger in Train C, and lead the cooling water of the additional cooling system to the RIS-RHR heat exchanger in Train A and the RIS-RHR heat exchanger in Train B through the PTR heat exchanger in Train C.

[0109] This step is for the case of leading to the RIS-RHR heat exchanger in Train C. There is a third valve that can be opened and closed between the PTR heat exchanger in Train A and the RIS-RHR heat exchanger in Train C. When the cooling of the RIS-RHR heat exchanger in Train C fails, a failure signal will be sent. The temporary cold source system will direct the failure signal to the third protection shutdown instruction and control the third valve to close, so as to shut down the RIS-RHR heat exchanger in Train C. The cooling water that originally flowed through this part will all flow through the other two trains (the RIS-RHR heat exchanger in Train A and the RIS-RHR heat exchanger in Train B), thus ensuring that the primary circuit can still be cooled by the other two trains of RIS-RHR heat exchangers in the case of the cooling failure of the RIS-RHR heat exchanger in Train C. It should be noted that although it is led to the RIS-RHR heat exchanger in Train C only after the cooling failure of the RIS-RHR heat exchanger in Train A, the RIS-RHR heat exchanger in Train A is still available. Therefore, when the cooling of the RIS-RHR heat exchanger in Train C fails, it can still be led to the RIS-RHR heat exchanger in Train A for cooling. Among them, the cooling schematic diagram of the RIS-RHR heat exchanger in Train C is shown in Figure 12

[0110] In addition, since there are no heat loads such as main pumps and RCV letdown heat exchangers in the Train C loop (i.e., the loop between the PTR heat exchanger in Train C and the RIS-RHR heat exchanger in Train C), the Train C loop can be isolated and does not need to operate. Specifically, the temporary bypass of the PTR heat exchanger in Train C is removed and a blind flange is installed to prevent water from flowing through the PTR heat exchanger in Train C

[0111] This step aims at the situation in the prior art where the ECS intermediate loop is only connected to the EHR and the PTR heat exchanger in Train A. By connecting the three trains of RIS-RHR heat exchangers to the ECS intermediate loop, it realizes that one train of ECS drives three trains, making the heat transfer area more redundant and ensuring that three trains of RIS-RHR heat exchangers are mutually backup during the primary circuit cooling in the cold commissioning period

[0112] As Figure 9 shown, the method for realizing the cold functional test of a nuclear power plant includes S81 - S83

[0113] S81. Control the containment heat removal system to enter the backwashing or recirculation mode

[0114] S82. Preset the cooling water flow rate required for the main pump motor and control the operation of the main pump motor

[0115] S83. When the makeup water flow rate of the IRWST pool is adjusted to the predetermined water flow rate, start the temporary drain pump of the IRWST pool and adjust the drain flow rate through the temporary valve to maintain the liquid level of the IRWST pool at the predetermined liquid level

[0116] In this step, during the test, the heat in the cooling water system (RRI) circulation loop of the equipment is transferred to the IRWST pool by a device in the containment heat removal system (EHR). The IRWST pool removes the heat through the methods of "natural heat dissipation" and "online water replacement". Moreover, the temperature needs to be controlled at a predetermined temperature (such as below 45°C). Both EHR and RRI operate according to their designed operating conditions. Referring to the existing data, a simulation calculation is carried out for the containment heat exchanger, and the results are referred to Figure 13 As shown, in the containment heat exchanger, the inlet temperature on the tube side is 27.7°C, the pressure is 1.608 MPa.g, and the flow rate is 281.2 m 3 / h. The medium is SED demineralized water (i.e., the tube side inlet is replenished with SED water). The outlet temperature on the tube side is 37.2°C, and the outlet pressure is 1.4725 MPa.g; the inlet temperature on the shell side is 45°C, the pressure is 0.401 MPa.g, and the flow rate is 371 m 3 / h. The medium is SED demineralized water; the outlet temperature on the shell side is 37.8°C, the outlet pressure is 0.3725 MPa.g, and the heat load removed is 3.077 MW.

[0117] It can be seen from this that when the operating temperature of RRI does not exceed 45°C, by using the method of EHR reverse cooling of RRI, the heat load removed is 3.077 MW, which meets the cooling requirement that when the RIS motor and the RCV letdown heat exchanger are directly cooled by connecting to temporary SED water, the reverse cooling needs to remove a heat load of 2.828 MW.

[0118] During the specific implementation, the IRWST pool maintains a normal liquid level (such as 3.55 meters), and one column of the containment heat exchanger is selected (the containment heat exchanger has multiple columns, and only one column needs to be selected) and operates in the "backwashing / recycling mode of taking water from the RIS sump (i.e., the backwashing or recycling mode)". The RRI column corresponding to the selected column of the containment heat exchanger and the main pump motor operate under normal conditions. The flow rate of the main pump motor cooling water is set according to the test requirements. The flow rate on the RRI side of the containment heat exchanger is 371 m 3 / h. Other users configure the flow rate according to the actual situation, and adjust the makeup water flow rate of the IRWST pool to the predetermined water flow rate (such as 150 m 3 / h). At this time, start the temporary drain pump of the IRWST pool and adjust the drain flow rate through the temporary valve to make the liquid level of the IRWST pool stable at the predetermined liquid level (i.e., 3.55 meters), and then start the cold test.

[0119] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A temporary cold source system for the cold state functional test of a nuclear power plant, characterized in that, include: Temporary cooling water supply module, used to provide cooling water during the single system commissioning phase before cold testing; Containment ventilation and cooling module, used to dehumidify and cool the interior of the containment before the containment sealing test; The main pump motor test cooling module is used to perform the main pump motor test before the cold test to control the water temperature of the equipment cooling water system not to exceed the safety set value; The cold functional test cooling module is used to realize heat removal and cooling of the cold functional test of the nuclear power plant.

2. The temporary cooling source system according to claim 1, characterized in that: The temporary cooling water supply module is connected to the single system through a temporary water supply network and is used to provide cooling water to the single system to complete the first startup test, wherein the single system includes a safety injection system, a containment heat removal system, an equipment cooling water system, and a chemical and volume control system.

3. The temporary cold source system according to claim 1, characterized in that The containment ventilation and refrigeration module includes a containment cooling and ventilation system having a main air supply subsystem and a dedicated air cooling unit or a temporary refrigeration unit for providing cooling water to the main air supply subsystem.

4. The temporary cooling source system according to claim 3, characterized in that: The main air supply subsystem includes a fan, which is connected to a ring header and a distribution pipe network in sequence. The fan is used to cool the inhaled air and send it into the ring header, and then transport it to the target area through the distribution pipe network.

5. The temporary cold source system according to claim 4, characterized in that The main air supply subsystem also includes an EVR heat exchanger with a cooling coil; The dedicated air-cooling unit is provided with a chilled water pump for delivering cooling water, and the dedicated air-cooling unit is connected to the cooling coil of the EVR heat exchanger through a temporary pipeline and an island inlet pipeline; Alternatively, the temporary refrigeration unit includes a temporary refrigerator and a circulation pump, the temporary refrigerator is used to provide cooling water, the circulation pump is used to transport the cooling water provided by the temporary refrigerator, and the temporary refrigerator is connected to the cooling coil of the EVR heat exchanger through a temporary pipeline and an island inlet pipeline.

6. The temporary cold source system according to claim 1, characterized in that The cold function test cooling module includes: a primary cooling module and an equipment cooling water circulation loop cooling module. The primary cooling module is used to cool the primary heat load of the equipment cooling water system, and the equipment cooling water circulation loop cooling module is used to cool the residual heat load of the circulation loop of the equipment cooling water system.

7. The temporary cold source system according to claim 6, characterized in that, The temporary cold source system also includes an additional cooling system. The primary cooling module includes a RIS-RHR heat exchanger and a PTR heat exchanger connected to the RIS-RHR heat exchanger. Both the RIS-RHR heat exchanger and the PTR heat exchanger include columns A, B, and C. The RIS-RHR heat exchanger is connected to the intermediate circuit of the additional cooling system.

8. The temporary cold source system according to claim 7, wherein, The heat load of the primary circuit is the heat load generated by the circulation of one main pump, three RIS pumps and RCV pump minus the heat load generated by the RCV downstream heat exchanger, or the heat load of the primary circuit is the heat load generated by the circulation of three main pumps, three RIS pumps and RCV pump minus the heat load generated by the RCV downstream heat exchanger.

9. The temporary cold source system according to claim 6, characterized in that, The equipment cooling water circulation loop cooling module includes an IRWST water pool, the containment heat removal system includes a containment heat exchanger, and the IRWST water pool is connected to the containment heat exchanger; The main pump motor test cooling module is connected to the IRWST pool.

10. The temporary cold source system according to claim 9, characterized in that, The residual heat load of the circulation loop is the sum of the heat loads generated by the main pump motor, the RIS motor, the RCV letdown heat exchanger, the RCV motor, the self-circulation of the circulation loop, and the heat load of the motors in the equipment cooling water system.

11. A method for implementing a cold function test of a nuclear power plant, applied to the temporary cold source system according to any one of claims 1 to 10, characterized in that: It includes: Using the temporary cooling water supply module to provide cooling water during the single-system commissioning stage before the cold test; Using the containment ventilation and refrigeration module to dehumidify and refrigerate the inside of the containment before the containment leak-tightness test; Using the main pump motor test cooling module to perform the main pump motor test before the cold test to control the water temperature of the equipment cooling water system not to exceed the safety set value; Using the cold functional test cooling module to achieve heat extraction and cooling for the cold functional test of the nuclear power plant.

12. The method according to claim 11, applied to the temporary cooling source system according to any one of claims 7 to 8, characterized in that: It includes: Introduce the cooling water of the additional cooling system into the A train RIS-RHR heat exchanger through a temporary pipeline; Lead the failure signal of the A train RIS-RHR heat exchanger to the first protection closing instruction. If the cooling of the A train RIS-RHR heat exchanger fails, close the A train RIS-RHR heat exchanger, and lead the cooling water of the additional cooling system to the B train RIS-RHR heat exchanger and the C train RIS-RHR heat exchanger through the cooling side pipeline of the A train PTR heat exchanger.

13. The method according to claim 12, wherein It also includes: Introduce the cooling water of the additional cooling system into the B train RIS-RHR heat exchanger through the cooling side pipeline of the A train PTR heat exchanger and a temporary pipeline; Lead the failure signal of the B train RIS-RHR heat exchanger to the second protection closing instruction. If the cooling of the B train RIS-RHR heat exchanger fails, close the B train RIS-RHR heat exchanger, and lead the cooling water of the additional cooling system to the A train RIS-RHR heat exchanger and the C train RIS-RHR heat exchanger through the B train PTR heat exchanger.

14. The method according to claim 13, characterized in that It also includes: Guide the cooling water of the additional cooling system from the cooling side of the A train PTR heat exchanger to the cooling side of the C train PTR heat exchanger, and introduce it into the C train RIS-RHR heat exchanger through a temporary pipeline; Remove the temporary bypass of the C train PTR heat exchanger and install a blind plate; Lead the failure signal of the C train RIS-RHR heat exchanger to the third protection closing instruction. If the cooling of the C train RIS-RHR heat exchanger fails, close the C train RIS-RHR heat exchanger, and lead the cooling water of the additional cooling system to the A train RIS-RHR heat exchanger and the B train RIS-RHR heat exchanger through the C train PTR heat exchanger.

15. The method according to claim 11, applied to the temporary cooling source system according to any one of claims 9 to 10, characterized in that: It includes: Control the containment heat removal system to enter the backwashing or recirculation mode; Preset the cooling water flow rate required by the main pump motor and control the operation of the main pump motor; When the makeup water flow rate of the IRWST pool is adjusted to the predetermined water flow rate, start the temporary drain pump of the IRWST pool, and adjust the drain flow rate through a temporary valve to keep the liquid level of the IRWST pool at the predetermined liquid level.

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