Circulating flushing device and method for high-temperature and high-pressure test loop of research reactor

Abstract

The invention relates to the technical field of research reactor operation and maintenance, and provides a research reactor high-temperature and high-pressure test loop circulating flushing device and method.The research reactor high-temperature and high-pressure test loop circulating flushing device comprises a water tank, a flushing pump, a first filter and a second filter, and the first filter, the water tank, the flushing pump and the second filter are sequentially connected to the outlet end of a main pump unit; and finally, the air flows back to the heat exchange unit of the test loop through the second filter, so that a forced circulation external loop is formed, impurities in the test loop are effectively removed, and each loop is independently flushed step by step, so that the effect of single flushing is enhanced, the exposure dose time of operation and maintenance personnel is shortened, and the operation safety is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of research reactor operation and maintenance, and in particular to a high-temperature and high-pressure test loop circulating flushing device and method for a research reactor. Background Art

[0002] The high temperature and high pressure test loop is used for research reactor irradiation test facilities and simulates the actual service environment of fuel elements. It has an independent temperature, pressure and flow control system, and can perform steady-state irradiation tests under high neutron flux to verify whether the design, manufacturing process, performance and materials of the fuel elements meet the expected requirements. Usually after the loop construction is completed or the test project is completed, the main pipeline of the high temperature and high pressure test loop needs to be flushed to avoid the problem of valve jamming, flow orifice plate and instrument damage caused by particulate matter in the system pipeline, and to reduce the metal debris in the main pipeline from entering the reactor and generating radioactive nuclides after irradiation activation, which constitutes a radiation source in the coolant, resulting in an increase in radioactive waste generated by the test loop operation, which seriously affects the flow regulation of the main coolant system and even endangers the safe operation of the research reactor.

[0003] At present, in the joint flushing of the primary circuit of domestic nuclear power plants, the pump performance test and pipeline test are usually combined, and the flushing water is discharged from the storage tank into the pressure vessel, and then discharged from the pressure vessel to complete the pipeline flushing. However, a large number of pipelines related to the primary circuit of the third-generation nuclear power plant adopt passive design, so the joint flushing of the primary circuit also chooses a combination of high-pressure jet technology and manual scrubbing. However, there are still problems such as inconvenient operation, long exposure time of workers and poor flushing effect. Summary of the invention

[0004] The purpose of the present invention is to provide a high-temperature and high-pressure test loop circulating flushing device for a research reactor, which solves the above-mentioned technical problems, is easy to operate, effectively removes impurities in the test loop, reduces the exposure dose time of operation and maintenance personnel, and improves the safety of operation.

[0005] The present invention is achieved through the following technical scheme: a research reactor high-temperature and high-pressure test loop circulating flushing device, including a heat exchange unit and a main pump unit connected in sequence, the main pump unit is externally connected to a water tank through a pipeline, a first filter is connected between the water tank inlet and the main pump unit outlet, the water tank outlet is sequentially connected to a flushing pump and a second filter through a pipeline, and the second filter outlet is connected to the heat exchange unit inlet.

[0006] Furthermore, the heat exchange unit includes a first heat exchanger and a second heat exchanger which are connected in series or in parallel by switching valves, the heat exchange unit is connected in parallel with a first bypass valve, and the main pump unit is connected in parallel with a second bypass valve.

[0007] Furthermore, outlet ends of the first filter and the second filter are both connected to exhaust valves via branches.

[0008] Furthermore, the water tank comprises an inlet pipe and an outlet pipe, and the inlet pipe is above the liquid level.

[0009] Furthermore, an opening is provided on the top of the water tank, a sealing cover is connected to the opening, and a drain valve is connected to the bottom of the water tank through a pipeline.

[0010] Preferably, the cover is made of transparent glass.

[0011] Furthermore, the pipeline adopts a high-molecular polytetrafluoroethylene hose.

[0012] Furthermore, both the first filter and the second filter are basket filters.

[0013] A method for circulating and flushing a high-temperature and high-pressure test loop of a research reactor comprises the following steps:

[0014] Step S1, filling the water tank with water to discharge the gas in the circuit;

[0015] Step S2, adjusting the valve, firstly only flushing the circuits where the first bypass valve and the second bypass valve are located, and after flushing for a set time, flushing the circuit where the first heat exchanger is located and the circuit where the second heat exchanger is located respectively;

[0016] Step S3: After checking that there is no foreign matter in the first filter, stop flushing.

[0017] The present invention has at least the following advantages and beneficial effects:

[0018] (1) By sequentially connecting the first filter, water tank, flushing pump and second filter at the outlet of the main pump unit, and finally returning the second filter to the heat exchange unit of the test circuit, a forced circulation external loop is formed, which effectively removes impurities in the test circuit, reduces damage to the heat exchange unit and the main pump unit, and improves the reliability and service life of the entire system.

[0019] (2) By flushing each circuit separately in steps, the effect of a single flush is enhanced, the exposure time of operation and maintenance personnel is reduced, the safety of operation is improved, the flushing time and resource utilization are optimized, and foreign matter is effectively prevented from directly entering the heat exchange unit.

[0020] (3) An opening is provided in the water tank to vent the circuit system equipment. At the same time, deionized water can be connected to add water to the system. By checking the first filter, it can be determined whether the system is flushed clean. The operation and maintenance personnel only need to operate in the centralized operation area, which is convenient for the preparation of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 A schematic diagram of the structure of a high-temperature and high-pressure test loop circulating flushing device for a research reactor provided by the present invention;

[0023] Icons: 1-heat exchange unit, 11-first heat exchanger, 12-second heat exchanger, 13-first bypass valve, 2-main pump unit, 21-first pump body, 22-second pump body, 23-second bypass valve, 3-first filter, 4-water tank, 41-inlet pipe, 42-outlet pipe, 43-opening, 44-sealing cover, 45-drain valve, 5-flushing pump, 6-second filter, 7-exhaust valve. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example

[0027] like Figure 1As shown, in this embodiment, a circulating flushing device for a high-temperature and high-pressure test loop of a research reactor is mainly disclosed, which is suitable for flushing the main coolant system of the high-temperature and high-pressure test loop. The existing main coolant system is usually a closed loop of forced circulation, including a heat exchange unit 1 and a main pump unit 2 connected in sequence. The pressurized water from the main pump unit 2 flows through the test device and the heat exchange unit 1 in sequence, and finally returns to the main pump unit 2 to complete the cycle. The main structure of the flushing device includes a water tank 4, a flushing pump 5, a first filter 3 and a second filter 6. The main pump unit 2 is externally connected to the water tank 4 through a pipeline. The first filter 3 is connected between the inlet end of the water tank 4 and the outlet end of the main pump unit 2. The outlet end of the water tank 4 is sequentially connected to the flushing pump 5 and the second filter 6 through a pipeline. The outlet end of the second filter 6 is connected to the inlet end of the heat exchange unit 1; specifically, when it is necessary to flush the test circuit, the flushing device is installed and connected, and the valve is adjusted to connect the flushing device in series with the heat exchange unit 1 and the main pump unit 2 to form a forced circulation external circuit. The circulating flushing removes impurities in the test circuit, reduces damage to the heat exchange unit 1 and the main pump unit 2, and improves the reliability and service life of the entire system. The arrangement of the first filter 3 and the second filter 6 improves the pipeline flushing effect and prevents the risk of foreign matter being introduced into the test circuit again. It should be noted that the flushing device is centrally fixed in the process room. When the system is flushed, the operation and maintenance personnel only need to operate in the centralized operation area, which reduces the difficulty of the circulating flushing operation and the manpower investment cost.

[0028] Furthermore, in a specific implementation, the heat exchange unit 1 provided in the embodiment of the present invention includes a first heat exchanger 11 and a second heat exchanger 12 connected in series or in parallel by switching valves, the heat exchange unit 1 is connected in parallel with a first bypass valve 13, the main pump unit 2 includes a first pump body 21 and a second pump body 22 connected in parallel, and the main pump unit 2 is connected in parallel with a second bypass valve 23; specifically, series or parallel operation can be achieved by switching valves, and the flow path of the fluid can be flexibly adjusted. This embodiment can form three flushing paths, the first of which is a loop flowing through the first bypass valve 13 and the second bypass valve 23 connected in series, the second is a loop flowing through the first heat exchanger 11 and the main pump unit 2 connected in series, and the third is a loop flowing through the second heat exchanger 12 and the main pump unit 2 connected in series, and three flushings are performed respectively, thereby enhancing the effect of a single flushing.

[0029] Furthermore, in a specific implementation, the outlet ends of the first filter 3 and the second filter 6 provided in the embodiment of the present invention are connected to an exhaust valve 7 through a branch. Specifically, when detecting the internal conditions of the first filter 3 and the second filter 6, it is necessary to open the exhaust valve 7 first to reduce the internal pressure and avoid overflow of flushing water.

[0030] Furthermore, in a specific implementation, the water tank 4 provided in the embodiment of the present invention includes an inlet pipe 41 and an outlet pipe 42, and the inlet pipe 41 is above the liquid level; specifically, the inlet pipe 41 and the outlet pipe 42 can be arranged on the same side of the water tank 4, and adopt the form of water inlet at the top and water outlet at the bottom. The outlet pipe 42 is located below the liquid level and close to the bottom of the water tank 4, and the inlet pipe 41 is above the liquid level. The liquid level of the water tank 4 submerges the pipe mouth, which is beneficial to the exhaust of the system and the realization of the flushing cycle; preferably, an opening 43 is provided on the top of the water tank 4, and the opening 43 is connected with a cover 44, and the cover 44 is made of transparent glass material, which is convenient for exhausting the flushing loop pipeline and observing the liquid level of the water tank 4, and it is convenient to add water when the liquid level drops, while reducing the splashing of the flushing medium and pollution of the environment. The bottom of the water tank 4 is connected with a drain valve 45 through a pipeline to facilitate drainage after flushing.

[0031] Furthermore, in the specific implementation, the above-mentioned pipeline provided in the embodiment of the present invention adopts a polymer polytetrafluoroethylene hose, which has good physical properties and good bending performance, and is easy to install in a narrow process room; it has strong resistance to positive and negative pressures, and is not easily deformed by changes in system pressure during the flushing process; it is resistant to high temperatures, and the water temperature during the flushing process will rise due to the heat generated by the flushing pump 5, and the polymer polytetrafluoroethylene hose must be resistant to high temperatures of up to 120°C; it is corrosion-resistant, and drugs will be added during the flushing process for chemical cleaning, and the polymer polytetrafluoroethylene hose pipe wall and joints must be corrosion-resistant and rust-proof to avoid the introduction of foreign matter again.

[0032] Furthermore, in a specific implementation, the first filter 3 and the second filter 6 provided in the embodiment of the present invention both adopt basket filters. Specifically, the basket filter can adopt the existing technology, with the fluid entering from the upper part and flowing out from the lower part. After the fluid enters the filter barrel with a filter screen of a certain specification, its impurities are blocked by the filter screen, and the clean filtrate is discharged from the filter outlet. When checking whether there are any foreign objects in the entire system, just take out the detachable filter barrel in the basket filter, check the filter screen and reinstall it before continuing to use it.

[0033] In this embodiment, a method for circulating and flushing a high-temperature and high-pressure test loop of a research reactor is also disclosed, comprising the following steps:

[0034] Step S1, the water tank 4 is filled with water to discharge the gas in the circuit; it should be noted that the main coolant system of the test circuit needs to be welded with a reserved flange for external connection to ensure the detachable connection of the flushing device; by adding deionized water into the water tank 4, the system circuit is filled with water to drive out the gas, and the circuit is checked for leaks;

[0035] Step S2, adjusting the valve, first flush only the circuits where the first bypass valve 13 and the second bypass valve 23 are located, and after the flushing setting time, flush the circuits where the first heat exchanger 11 and the second heat exchanger 12 are located respectively; specifically, adopting step-by-step flushing, each circuit is flushed separately for 30 minutes, which can be efficiently cleaned for different equipment, is simple to operate, avoids unnecessary energy consumption and failure risks that may be caused by one-time large-scale flushing, not only improves the safety of operation, but also optimizes the flushing time and resource utilization; flushing the bypass pipeline first can effectively prevent foreign matter from directly entering the heat exchange unit 1, and increase the flushing time;

[0036] Step S3, after checking that no foreign matter is added to the first filter 3, stop flushing; it should be noted that, during the flushing process, only the first filter 3 is checked, and the second filter 6 is only used as a safety measure to prevent the introduction of new foreign matter into the loop system, and has no effect on the flushing result. The second filter 6 is only checked once after the flushing is completed. The acceptance standard is that no foreign matter is found in the first filter 3 for two consecutive inspections, and then the flushing can be stopped, and then the flushing device is removed and the valve status of the main coolant system is restored; wet maintenance is adopted for maintenance after flushing, and the main coolant system is filled with water and a certain concentration of hydrazine is added to reduce the oxygen concentration and reduce corrosion.

[0037] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A research reactor high temperature and high pressure test loop circulation flushing device, comprising a heat exchange unit (1) and a main pump unit (2) connected in sequence, characterized in that: The main pump unit (2) is externally connected to a water tank (4) via a pipeline; a first filter (3) is connected between the inlet end of the water tank (4) and the outlet end of the main pump unit (2); the outlet end of the water tank (4) is sequentially connected to a flushing pump (5) and a second filter (6) via a pipeline; the outlet end of the second filter (6) is connected to the inlet end of the heat exchange unit (1).

2. A research reactor high temperature and high pressure test loop circulating flushing device as claimed in claim 1, characterized in that: The heat exchange unit (1) comprises a first heat exchanger (11) and a second heat exchanger (12) which are connected in series or in parallel by switching valves; the heat exchange unit (1) is connected in parallel with a first bypass valve (13); and the main pump unit (2) is connected in parallel with a second bypass valve (23).

3. A research reactor high temperature and high pressure test loop circulating flushing device as claimed in claim 1, characterized in that: The outlet ends of the first filter (3) and the second filter (6) are both connected to an exhaust valve (7) via a branch line.

4. A research reactor high temperature and high pressure test loop circulating flushing device as claimed in claim 1, characterized in that: The water tank (4) comprises an inlet pipe (41) and an outlet pipe (42), wherein the inlet pipe (41) is above the liquid level.

5. A research reactor high temperature and high pressure test loop circulating flushing device as claimed in claim 1, characterized in that: The top of the water tank (4) is provided with an opening (43), the opening (43) is connected to a sealing cover (44), and the bottom of the water tank (4) is connected to a drain valve (45) via a pipeline.

6. A research reactor high temperature and high pressure test loop circulating flushing device as claimed in claim 5, characterized in that: The sealing cover (44) is made of transparent glass.

7. A research reactor high temperature and high pressure test loop circulating flushing device as claimed in claim 1, characterized in that: The pipeline adopts a high molecular polytetrafluoroethylene hose.

8. A research reactor high temperature and high pressure test loop circulating flushing device as claimed in claim 1, characterized in that: The first filter (3) and the second filter (6) are both basket filters.

9. A flushing method for a high temperature and high pressure test loop circulating flushing device for a research reactor based on claim 2, characterized in that: The following steps are involved: Step S1, the water tank (4) is filled with water to discharge the gas in the circuit; Step S2, adjusting the valve, firstly only flushing the circuits where the first bypass valve (13) and the second bypass valve (23) are located, and after flushing for a set time, flushing the circuits where the first heat exchanger (11) and the circuits where the second heat exchanger (12) are located respectively; Step S3: After checking that no foreign matter is added to the first filter (3), stop flushing.

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