CN113782237B - Maintenance method for seal section of reactor core measurement system - Google Patents
Maintenance method for seal section of reactor core measurement system Download PDFInfo
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- CN113782237B CN113782237B CN202110888843.XA CN202110888843A CN113782237B CN 113782237 B CN113782237 B CN 113782237B CN 202110888843 A CN202110888843 A CN 202110888843A CN 113782237 B CN113782237 B CN 113782237B
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- 238000005259 measurement Methods 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 39
- 238000012423 maintenance Methods 0.000 title claims description 11
- 238000007789 sealing Methods 0.000 claims abstract description 96
- 230000000903 blocking effect Effects 0.000 claims abstract description 20
- 238000012360 testing method Methods 0.000 claims description 19
- 238000002955 isolation Methods 0.000 claims description 13
- 230000035515 penetration Effects 0.000 claims description 13
- 239000000446 fuel Substances 0.000 claims description 6
- 230000008439 repair process Effects 0.000 claims description 6
- 238000004891 communication Methods 0.000 claims description 5
- 230000000149 penetrating effect Effects 0.000 claims description 4
- 230000007547 defect Effects 0.000 abstract description 5
- 238000011144 upstream manufacturing Methods 0.000 description 8
- 239000007788 liquid Substances 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000010276 construction Methods 0.000 description 3
- 239000003758 nuclear fuel Substances 0.000 description 3
- 235000011089 carbon dioxide Nutrition 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
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- 238000005192 partition Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
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Classifications
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C17/00—Monitoring; Testing ; Maintaining
- G21C17/017—Inspection or maintenance of pipe-lines or tubes in nuclear installations
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Abstract
The application relates to a method for overhauling a sealing section of a reactor core measurement system, which comprises the following steps: reducing the pressure in the main passage and withdrawing the finger sleeve portion; ice blocking the main passage at a position between the reactor pressure vessel and the sealing section to separate a sub-passage in the main passage at a side close to the sealing section; releasing the residual pressure within the sub-passageway; disassembling the sealing section; and taking out the first sealing element in the sealing section and overhauling the first sealing element. According to the method for overhauling the sealing section of the reactor core measurement system, after the pressure in the main passage of the system is partially reduced, the main passage is subjected to ice blocking, the sub-passages are separated from one side, close to the sealing section, in the main passage, and the sub-passages can be subjected to independent pressure relief under the working condition that the system keeps under pressure, so that the sealing section is overhauled. The method has the advantages that the sealing section of the reactor core measuring system is overhauled under the working condition of pressure, the state withdrawal depth of the overhauling time group is reduced, the operation steps during overhauling are reduced, and the period of defect treatment of the sealing section is shortened.
Description
Technical Field
The application relates to the technical field of seal segment maintenance, in particular to a method for maintaining a seal segment of a reactor core measurement system.
Background
In a nuclear power plant, a plurality of neutron fluence rate measurement channels in a reactor core measurement system (RIC) are distributed in a plurality of fuel assemblies respectively. In the measurement channel of the fuel assembly, a thimble tube is inserted from the bottom of the core, and a detector moves inside the thimble tube, thereby measuring the neutron fluence rate point by point over the entire height of the core. Wherein a circuit pressure boundary is formed by the seal segments, a static and dynamic seal is established between the guide tube and the guide sleeve, and leakage is not allowed.
In the related technology, when leakage occurs in a sealing section of the reactor core measurement system, the unit needs to be cooled by the RRA in a normal shutdown mode, and then is withdrawn to an MCS maintenance shutdown mode or an RCD complete unloading mode, namely, the pressure of a first loop of the unit is reduced to the atmospheric pressure, and after all nuclear fuel assemblies are removed, maintenance is carried out, so that the operation is complex and the construction period is long.
Disclosure of Invention
Accordingly, it is necessary to provide a method for repairing a seal section of a core measurement system, which aims at the problems of complicated repair operation and long construction period of the seal section of the core measurement system.
The embodiment of the application provides a method for overhauling a sealing section of a reactor core measurement system, which comprises the following steps:
reducing the pressure in the main passage and withdrawing the finger sleeve portion; the main passage is positioned between the finger sleeve and the guide pipe sleeved outside the finger sleeve and is communicated with the reactor pressure vessel;
ice blocking the main passage at a position between the reactor pressure vessel and the sealing section to separate a sub-passage in the main passage at a side close to the sealing section; the finger sleeve is penetrated into the fuel assembly in the reactor pressure vessel, and the sealing section is positioned at one end, which is away from the reactor pressure vessel, outside the guide pipe;
releasing the residual pressure within the sub-passageway;
disassembling the sealing section;
and taking out the first sealing element in the sealing section and overhauling the first sealing element.
In one embodiment, the step of ice blocking the main passageway at a location between the reactor pressure vessel and the seal segment comprises:
ice blocking is carried out on a main passage sleeved at the position between the penetrating piece outside the guide pipe and the isolating valve; the penetration is located between the reactor pressure vessel and the seal segment, and the isolation valve is located between the penetration and the seal segment.
In one embodiment, the step of releasing the residual pressure within the sub-passage comprises:
removing a second seal on the back pressure joint in communication with the sub-passageway to relieve residual pressure within the sub-passageway; the back pressure joint is located between the isolation valve and the seal segment.
In one embodiment, the step of disassembling the seal segment comprises:
cutting off a thrust section and an extension section which are connected with the finger sleeve, and dismantling a sleeve in the sealing section to enable the sub-passage to be communicated with the outside; one end of the finger sleeve, which is away from the reactor pressure vessel, passes through the sealing section and is connected with the thrust section and the extension section, and one end of the sleeve is sleeved at the end part of the guide pipe.
In one embodiment, the step of removing the first seal in the seal segment and performing service includes:
the sub-passageway is pressurized by the back pressure joint to flush the first seal out of the seal segment.
In one embodiment, the step of pressurizing the sub-passageway by the back pressure joint includes:
one end of the pressure line is connected to the back pressure joint, the other end of the pressure line is connected to the pressure pump, and the sub-passage is pressurized by the pressure pump.
In one embodiment, after the step of removing the first seal in the seal segment and performing service, the steps of:
the first seal and sleeve are reinstalled and the seal segment is subjected to a first tightness test.
In one embodiment, after the step of reinstalling the first seal and sleeve, performing a first tightness test on the seal segment and testing for compliance, the method further comprises the steps of:
and reconnecting the thrust section and the extension section with the finger sleeve, removing the ice plug to reconnect the main passage, and carrying out ice plug again after the finger sleeve is restored to the original position, and carrying out a second tightness test on the sealing section.
In one embodiment, the step of performing a tightness test on the seal segment comprises:
the sub-passage is pressurized by the back pressure joint to check whether leakage occurs at the seal section.
In one embodiment, after the step of performing a second tightness test on the sealing section and passing the test, the method further comprises the following steps:
the second seal on the back pressure joint is reinstalled.
According to the method for overhauling the sealing section of the reactor core measurement system, after the pressure in the main passage of the system is partially reduced, the main passage is subjected to ice blocking, the sub-passage is separated from one side, close to the sealing section, in the main passage, and the sub-passage can be subjected to independent pressure relief under the working condition that the system keeps the pressure so as to overhauling the sealing section. The method has the advantages that the sealing section of the reactor core measuring system is overhauled under the working condition of pressure, the state withdrawal depth of the overhauling time group is reduced, the operation steps during overhauling are reduced, and the period of defect treatment of the sealing section is shortened.
Drawings
FIG. 1 is a cross-sectional view of a structure of a core measurement system in a method of servicing a seal section of the core measurement system according to one embodiment of the present application;
FIG. 2 is an enlarged schematic view of FIG. 1 at A;
FIG. 3 is a flow chart of a method for servicing a seal section of a core measurement system according to one embodiment of the present disclosure;
fig. 4 is a schematic flow chart of a method for repairing a seal segment of a core measurement system according to another embodiment of the present application.
Detailed Description
In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is, however, susceptible of embodiment in many other forms than those described herein and similar modifications can be made by those skilled in the art without departing from the spirit of the application, and therefore the application is not to be limited to the specific embodiments disclosed below.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Fig. 1 is a structural cross-sectional view of a core measurement system in a method for repairing a seal section of the core measurement system according to an embodiment of the present application, and fig. 2 is an enlarged schematic view at a in fig. 1.
Referring to fig. 1 to 2, the core measurement system in the overhaul method according to the embodiment of the present application includes a thimble 110, a thrust segment 310, an extension segment 320, a guide pipe 120 and a seal segment 200 that are disposed on the thimble 110 in a penetrating manner, wherein one end of the thimble 110 passes through a bottom head 180 of the reactor and is disposed in a fuel assembly 170 of the reactor, a guide pipe 120 is sleeved on a portion of the thimble 110 located outside the reactor, and the guide pipe 120 is not attached to the thimble 110 but a certain gap is left between the thimble 110 and the guide pipe. It should be noted that, the guide tube 120 is not sleeved outside the entire finger sleeve 110, and the end of the finger sleeve 110 away from the fuel assembly 170 is penetrated out of the guide tube 120 and connected to the thrust section 310 and the extension section 320. A sealing section 200 is provided at the interface of the finger sleeve 110 and the guide tube 120 to achieve a seal between the finger sleeve 110 and the guide tube 120. Wherein the sealing section 200 is located at the end of the guide tube 120, and a first sealing member 210 is disposed in a sleeve 220 in the sealing section 200 to realize the sealing function of the sealing section 200. Thus, a complete annular channel, i.e., a main passage 130, is formed in the gap between the guide tube 120 and the thimble tube 110, the main passage 130 being in communication with the reactor pressure vessel, and a liquid medium being present in the main passage 130 to effect pressure transfer. Between the lower head 180 and the sealing section 200 of the reactor, the guide pipe 120 is first passed through a penetration 140, such as a shielding wall or the like, and then the guide pipe 120 is provided with an isolation valve 150 and a back pressure joint 160 in sequence. The back pressure joint 160 is provided with a channel communicated with the main passage 130, and the back pressure joint 160 is also provided with a second sealing element capable of sealing the channel. The first seal 210 is a generic term for the components that perform a sealing function in the seal segment 200, and the second seal is a generic term for the components that perform a sealing function in the back pressure joint 160, that is, the first seal 210 and the second seal may each include one or more seal components, and when they include a plurality of seal components, the seal components may be the same type or different types, and are not limited herein.
In the related technology, when leakage occurs in a sealing section of the reactor core measurement system, the unit needs to be cooled by the RRA in a normal shutdown mode, and then is withdrawn to an MCS maintenance shutdown mode or an RCD complete unloading mode, namely, the pressure of a first loop of the unit is reduced to the atmospheric pressure, and after all nuclear fuel assemblies are removed, maintenance is carried out, so that the operation is complex and the construction period is long.
FIG. 3 is a flow chart of a method for servicing a seal section of a core measurement system according to one embodiment of the present application.
To at least partially solve the above problems, please refer to fig. 1-2 and fig. 3 in combination, an embodiment of the present application provides a method for repairing a seal section of a core measurement system, the method comprising the steps of:
s102, reducing the pressure in the main passage 130, and partially extracting the finger sleeve 110 together with the thrust section 310 and the extension section 320. Wherein the main passage 130 is located between the thimble 110 and the guide tube 120 sleeved outside the thimble 110, and the main passage 130 communicates with the reactor pressure vessel.
The first circuit pressure was 25bar when the reactor was in RRA cool down normal shutdown mode. For facilitating subsequent operations, the pressure in the main passage 130 may be reduced to not higher than 10bar, such as 9bar, 8.5bar, 7bar, etc., for a suitable reduction in the primary circuit pressure. After loosening the compression nuts upstream and downstream of the seal segment 200, the finger sleeve 110, along with the thrust segment 310 and extension segment 320, is withdrawn about 50cm for subsequent service operations.
S104, ice blocking is performed on the main passage 130 located at a position between the reactor pressure vessel and the seal section 200 to partition the sub-passage 131 at a side of the main passage 130 near the seal section 200.
More specifically, the main passage 130 located at the position between the penetration 140 and the isolation valve 150 is ice-blocked, and since the liquid medium is contained in the main passage 130, the main passage 130 located at the position between the penetration 140 and the isolation valve 150 is ice-blocked, a pressure boundary of the main passage 130 may be formed at the position, and another pressure boundary of the main passage 130 may be formed at the position of the sealing section 200. The main passageway 130 is separated at the ice shutoff location, forming a sub-passageway 131 between the shutoff location and the seal segment 200. The ice blocking operation may be implemented by using an ice blocking device, which may include a dry ice generator (such as a liquid carbon dioxide bottle), and the liquid medium in the annular channels inside the finger sleeve 110 and the guide tube 120 is cooled by using dry ice to solidify and block. After the ice blockage is finished, the liquid medium is boiled off, and normal use of the finger sleeve 110 is not affected.
S106, releasing the residual pressure in the sub-passage 131.
After step 104, one pressure boundary of the main passageway 130 is formed at the ice-blocking location, another pressure boundary of the main passageway 130 is formed at the seal segment 200 location, and the main passageway 130 is partitioned at the ice-blocking location to form a sub-passageway 131 between the blocking location and the seal segment 200. In this manner, the sub-passage 131 alone may be depressurized to facilitate servicing the seal segment 200 without affecting the system pressure within the reactor. The method realizes the overhaul of the sealing section 200 of the reactor core measurement system under the working condition of pressure, reduces the state withdrawal depth of the overhaul opportunity group, reduces the operation steps during the overhaul, and shortens the period of defect treatment of the sealing section 200.
S108, disassembling the sealing section 200.
In step S106, the residual pressure in the sub-passage 131 is released, i.e. the sub-passage 131 between the ice-blocking position and the seal segment 200 has been depressurized, at which point the upstream gland nut may be completely loosened, and the seal segment 200 disassembled at normal pressure for servicing.
And S110, taking out the first sealing element 210 in the sealing section 200 and overhauling.
After disassembly of the seal segment 200, the first seal 210 in the seal segment 200 may be removed and the upstream and downstream sealing surfaces in the seal segment 200, the surface of the finger sleeve 110, and the first seal 210 inspected, and after confirming the failure point, the defective component or assembly may be repaired or replaced.
According to the method for overhauling the sealing section of the reactor core measurement system, after the pressure in the main passage 130 of the system is partially reduced, the main passage 130 is subjected to ice blocking, the sub-passages 131 are separated from one side, close to the sealing section 200, in the main passage 130, and the sub-passages 131 can be subjected to independent pressure relief under the working condition that the system keeps the pressure so as to overhaul the sealing section 200. The method realizes the overhaul of the sealing section 200 of the reactor core measurement system under the working condition of pressure, reduces the state withdrawal depth of the overhaul opportunity group, reduces the operation steps during the overhaul, and shortens the period of defect treatment of the sealing section 200.
Since the guide pipe 120 is provided with the isolation valve 150 and the back pressure joint 160 in order after passing through the penetration 140 between the lower head 180 and the sealing section 200 of the reactor, it is necessary to select an appropriate position for the subsequent operation when ice blocking the main passage 130. Thus, in some embodiments, step S104 includes: the main passage 130 at a position between the penetration 140 and the isolation valve 150 is ice-blocked. Wherein the penetration 140 is located between the reactor pressure vessel and the seal segment 200, and the isolation valve 150 is located between the penetration 140 and the back pressure joint 160. As shown in fig. 1 and 2, after ice blocking is performed at a position between the penetration 140 and the isolation valve 150, a sub-passage 131 between the blocking position and the sealing section 200 is formed, facilitating the subsequent repair operation.
As described above, since the back pressure joint 160 is provided with the channel communicating with the main passage 130, the back pressure joint 160 is further provided with the second sealing member capable of sealing the channel, and thus, in some embodiments, the step S106 includes: the second seal on the back pressure fitting 160 in communication with the sub-passageway 131 is removed to relieve the residual pressure within the sub-passageway 131. Wherein the back pressure joint 160 is located between the isolation valve 150 and the seal segment 200. After the second sealing member on the back pressure joint 160 is removed, the sub-passage 131 communicates with the outside through the channel in the back pressure joint 160, and the residual pressure in the sub-passage 131 can be released.
To remove the first seal 210 in the seal segment 200, the seal segment 200 needs to be disassembled, specifically, in some embodiments, step S108 includes: the thrust section 310 and the extension section 320 connected to the finger sleeve 110 are cut off, and the sleeve 220 in the seal section 200 is removed to allow the sub-passage 131 to communicate with the outside. Wherein, the end of the finger sleeve 110 facing away from the reactor pressure vessel passes through the sealing section 200 and is connected with the thrust section 310 and the extension section 320, and one end of the sleeve 220 is sleeved at the end of the guide tube 120. As shown in fig. 1, after the thrust section 310 and the extension section 320 connected to the finger sleeve 110 are removed, the sleeve 220 having one end of the seal section 200 sleeved on the finger sleeve 110 can be removed, and at this time, the sub-passage 131 is in communication with the outside. The first seal 210 in the seal segment 200 may then be removed from the sleeve 220 for servicing.
In the related art, in order to remove the first seal 210 in the seal segment 200, a scooping tool is typically used to scoop the first seal 210 into the seal segment 200, which is easy to damage the sealing surface of the seal sleeve 220 and the surface of the finger sleeve 110 upstream of the seal segment 200, causing irreversible damage to the seal segment 200 and the finger sleeve 110, affecting the service life of the system. To solve the above problem, in some embodiments, step S110 includes: the sub-passageway 131 is pressurized by the back pressure joint 160 to flush the first seal 210 out of the seal segment 200. Since the sub-passage 131 communicates with the outside through the passage in the back pressure joint 160 after the second seal member on the back pressure joint 160 is removed, the pressure can be applied to the sub-passage 131 through the passage in the back pressure joint 160, and the first seal member 210 in the seal section 200 is punched out by the pressure. The method adopts a pressurizing mode to take out the first sealing element 210, does not need to penetrate a tool into the sealing section 200, does not damage the sealing surface of the sealing sleeve 220 and the surface of the finger sleeve 110 at the upstream of the sealing section 200, and prolongs the service life of the sealing section 200 to a certain extent.
Based on the above embodiment, the step of pressurizing the sub-passage 131 by the back pressure joint 160 includes: one end of the pressure line 410 is connected to the back pressure joint 160, the other end of the pressure line 410 is connected to the pressure pump 420, and the pressure pump 420 pressurizes the sub-passage 131. As shown in fig. 1, the pressurizing device 400 is connected to the back pressure joint 160, the pressurizing device 400 includes a pressure pump 420, the pressure pump 420 includes an outlet end and an inlet end, the outlet end is connected to the back pressure joint 160 through a pressure line 410, the inlet end is connected to a water source through a water inlet pipe, so that water is fed into the inner annular channels of the finger sleeve 110 and the guide pipe 120 through the pressure pump 420, the water applies pressure to the walls of the finger sleeve 110 and the guide pipe 120 in the inner annular channels between the finger sleeve 110 and the guide pipe 120, and the applied pressure can be set according to the pressure when the unit is operated. The pressure line 410 is also provided with a pressure gauge for indicating the magnitude of pressure applied to the inner annular passage, an exhaust valve for exhaust, a relief valve, and the like. The pressure pump 420 may be a hand pump.
Fig. 4 is a schematic flow chart of a method for repairing a seal segment of a core measurement system according to another embodiment of the present application.
Referring to fig. 4 in conjunction with fig. 1-2, in other embodiments, embodiments of the present application provide a method of servicing a seal segment of a core measurement system, the method comprising the steps of:
s202, the pressure in the main passage 130 is reduced, and the finger sleeve 110 is partially extracted together with the thrust section 310 and the extension section 320.
S204, ice blocking is performed on the main passage 130 located at a position between the penetration 140 and the isolation valve 150 to separate the sub-passage 131 at a side of the main passage 130 near the seal segment 200.
S206, releasing the residual pressure in the sub-passage 131.
S208, disassembling the seal segment 200.
And S210, taking out the first sealing element 210 in the sealing section 200 and overhauling.
S212, reinstalling the first sealing element 210 and the sleeve 220, and performing a first tightness test on the sealing section 200.
After repair or replacement of defective components or assemblies is completed in the seal section 200 of the core measurement system, the disassembled components need to be reassembled for continued normal operation. Therefore, first seal 210 and sleeve 220 are reinstalled and seal segment 200 is tested for a first tightness to ensure that seal segment 200 is leak-tight enough to meet system operating requirements.
S214, reconnecting the thrust section 310 and the extension section 320 with the finger sleeve 110, removing the ice blockage to enable the main passage 130 to be communicated again, restoring the finger sleeve 110, the thrust section 310 and the extension section 320 together, tightening torque on the upstream and downstream nuts, performing ice blockage again, and performing a second tightness test on the seal section 200.
After the first tightness test performed on the seal section 200 is completed to ensure that the tightness of the seal section 200 meets the requirements, the thrust section 310 and the extension section 320 removed in the step S208 are re-welded with the finger sleeve 110, and the finger sleeve 110 is returned to its original position by removing the ice blockage, i.e. the finger sleeve 110 is returned to the position where it should be in the normal working state. Then, the original ice blocking position is blocked again, at this time, the sealing section 200 is communicated with the sub-passage 131, and a second tightness test is performed on the sealing section 200, that is, whether the tightness in the whole sub-passage 131 meets the operation requirement is tested.
In steps S212 and S214, the seal segment 200 is tested for first and second tightness, respectively, and in some embodiments, the sub-passageway 131 may be pressurized from the back pressure joint 160 to check for leaks at the seal segment 200. After the second sealing element on the back pressure joint 160 is removed, the sub-passage 131 is communicated with the outside through the channel in the back pressure joint 160, at this time, the pressure can be applied to the sub-passage 131 by means of the channel in the back pressure joint 160, and under the action of the pressure, whether the sealing section 200 leaks or not is detected, so that the tightness of the sealing section 200 can be verified.
And S216, after the tightness of the sealing section 200 is confirmed to meet the requirement, reinstalling the second sealing member.
When the second tightness test is completed on the sealing section 200, after the sealing performance of the sealing section 200 is confirmed to meet the requirement, the second sealing element at the back pressure joint 160 can be reinstalled, and after the locking plates and screws of the upstream and downstream nuts of the sealing section 200 are reinstalled, the whole system is returned to the normal working state.
In summary, in the method for overhauling the seal section of the reactor core measurement system according to the embodiment of the present application, the sub-passage 131 can be depressurized independently under the condition that the system keeps the pressure, so as to overhaul the seal section 200. The method has the advantages that the maintenance of the sealing section 200 of the reactor core measurement system under the working condition of pressure is realized, the state withdrawal depth of the maintenance set is reduced, the re-disassembly of nuclear fuel and the pulling out of the old finger sleeve 110 are avoided, the operation steps during the maintenance are reduced, the period of defect treatment of the sealing section 200 is shortened, and the available power generation time of the nuclear power unit is prolonged. Meanwhile, the overhauling method of the embodiment of the application avoids using a hard packing picking tool to pick out the packing, and can effectively protect the sealing surface of the upstream sealing sleeve 220 and the surface of the finger sleeve 110. In the case of a pressurized circuit, disassembly checks the seal segment 200 and proceeds without requiring a complete circuit pressure relief. Under the condition of the primary circuit with pressure, the sealing section 200 is subjected to tightness verification in advance, so that the situation that leakage is repeatedly treated again after ascending is avoided.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the claims. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.
Claims (9)
1. The maintenance method of the seal section of the reactor core measurement system is characterized by comprising the following steps of:
reducing the pressure in the main passage and withdrawing the finger sleeve portion; the main passage is positioned between the finger sleeve and the guide pipe sleeved outside the finger sleeve and is communicated with the reactor pressure vessel;
ice blocking the main passageway at a location between the reactor pressure vessel and the seal segment to separate a sub-passageway in the main passageway on a side of the main passageway adjacent the seal segment; the finger sleeve is arranged in the fuel assembly in the reactor pressure vessel in a penetrating way, and the sealing section is positioned at one end, which is away from the reactor pressure vessel, outside the guide pipe;
communicating the sub-passageway with the outside through a channel in a back pressure fitting in communication with the sub-passageway to relieve residual pressure within the sub-passageway;
disassembling the seal segment;
taking out the first sealing element in the sealing section and overhauling the first sealing element;
reinstalling the first seal and the sleeve within the seal segment, and performing a first tightness test on the seal segment;
after the first sealing test is qualified, removing ice blockage to enable the main passage to be communicated again;
and after the finger sleeve is restored to the original position, ice blocking is carried out again, and a second tightness test is carried out on the sealing section.
2. The core measurement system seal segment repair method of claim 1 wherein said step of ice blocking said main passageway at a location between a reactor pressure vessel and a seal segment comprises:
ice blocking is carried out on the main passage sleeved at the position between the penetrating piece outside the guide pipe and the isolating valve; the penetration is located between the reactor pressure vessel and the seal segment, and the isolation valve is located between the penetration and the seal segment.
3. The core measurement system seal segment service method of claim 2, wherein the step of relieving residual pressure within the sub-passage comprises:
removing a second seal on the back pressure joint to relieve residual pressure within the sub-passageway; the back pressure joint is located between the isolation valve and the seal segment.
4. The core measurement system seal segment repair method of claim 3, wherein the step of disassembling the seal segment comprises:
cutting off a thrust section and an extension section which are connected with the finger sleeve, and dismantling a sleeve in the sealing section to enable the sub-passage to be communicated with the outside; one end of the finger sleeve, which is away from the reactor pressure vessel, passes through the sealing section and is connected with the thrust section and the extension section, and one end of the sleeve is sleeved at the end part of the guide tube.
5. The method of servicing a seal segment of a core measurement system of claim 4, wherein the step of removing and servicing a first seal in the seal segment comprises:
pressurizing the sub-passageway from the back pressure junction to flush the first seal out of the seal segment.
6. The core measurement system seal segment service method of claim 5, wherein said step of pressurizing said sub-passage from said back pressure joint comprises:
and connecting one end of a pressure pipeline with the back pressure joint, connecting the other end of the pressure pipeline with a pressure pump, and pressurizing the interior of the sub-passage through the pressure pump.
7. The method of repairing a seal segment of a core measurement system according to claim 5, wherein after the first leak tightness test is passed, removing the ice plug to reconnect the main passage comprises:
and reconnecting the thrust section and the extension section with the finger sleeve, and removing the ice blockage to reconnect the main passage.
8. The core measurement system seal segment repair method of claim 7, wherein the step of performing a leak tightness test on the seal segment comprises:
pressurizing the sub-passage from the back pressure joint to check whether leakage occurs at the seal segment.
9. The method of servicing a seal segment of a core measurement system of claim 8, further comprising, after the step of performing a second leak tightness test on the seal segment and testing to be acceptable, the steps of:
reinstallation of the second seal on the back pressure fitting.
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