阅读说明：本技术 真空离线啜吸系统及检测方法 (Vacuum off-line sipping system and detection method ) 是由 郝庆军 邓志新 龚雪琼 周政 石中华 廖昌斌 邹森 于 2020-07-27 设计创作，主要内容包括：本发明属于核电维修技术领域,具体涉及一种真空离线啜吸系统及检测方法。本公开的检测方法在确保检测准确性的前提下,实现多啜吸筒分时同步交替检测,缩短检测时间。采用多个啜吸筒啜吸交替检测的方法将平均检测一组燃料组的时间缩短30％以上。此外,由于设计了多个啜吸筒,既可实现双啜吸筒交替检测工作,也可实现单啜吸筒独立检测工作,提高了系统的冗余性。(The invention belongs to the technical field of nuclear power maintenance, and particularly relates to a vacuum off-line sipping system and a detection method. The detection method disclosed by the invention realizes the time-sharing synchronous alternative detection of multiple sipping tubes on the premise of ensuring the detection accuracy, and shortens the detection time. The time for average detecting a group of fuel groups is shortened by more than 30% by adopting a method of sip alternation detection. In addition, due to the design of a plurality of sipping tubes, the alternate detection work of the double sipping tubes can be realized, the independent detection work of the single sipping tube can also be realized, and the redundancy of the system is improved.)

1. A vacuum offline sipping system, comprising: the system comprises a plurality of sipping barrels, a gas source, a first water source, a vacuum pump, a radioactivity detector, a spent water pool and an exhaust gas discharge system, wherein the gas source is used for outputting non-radioactive gas, and the first water source is used for conveying water;

the first vent of each sip tube is connected to the first connection point through a first vent valve, and the second vent of each sip tube is connected to the second connection point through a second vent valve;

the first connecting point is connected with a third connecting point through a first air source valve, the second connecting point is connected with the third connecting point through a second air source valve, and the third connecting point is connected with the air source;

the water inlet of each sipping barrel is connected with the fourth connection point through a water inlet valve, the water outlet of each sipping barrel is connected with the spent pool through a water outlet valve, and each water outlet valve can discharge the liquid of the sipping barrel connected with the sipping barrel to the spent pool;

the fourth connection point is connected with the first water source through a first water source valve;

the first connecting point is also connected with the vacuum pump through a first detection valve, the vacuum pump is connected with the radioactivity detector, and the radioactivity detector is connected with the exhaust emission system through a second detection valve;

the second connection point is connected between the radiation detector and the second detection valve by a third detection valve.

2. The vacuum offline sipping system of claim 1, wherein the vacuum offline sipping system further comprises: a gas pretreatment device;

the gas pretreatment device is connected between the first detection valve and the vacuum pump.

3. The vacuum offline sipping system of claim 1, wherein the vacuum offline sipping system further comprises: a second water source for outputting non-radioactive boric acid water, and the first water source for outputting boric acid water;

the fourth connection point is connected to the second water supply via a second water supply valve.

4. A detection method applied to the vacuum off-line sipping system according to any one of claims 1 to 3, the method comprising:

step 100, performing loop gas purging on the vacuum off-line sipping system;

step 101, after performing loop gas flushing on the vacuum off-line sipping system, selecting a sipping tube from the plurality of sipping tubes as a target sipping tube, using the remaining sipping tube as a standby sipping tube, and performing water flushing on the target sipping tube;

step 102, after the target sipping tube is subjected to water washing treatment, encapsulating the fuel assembly to be detected into the target sipping tube;

step 103, performing inflation and drainage treatment on the target sipping barrel after the water replacement treatment, flushing a plurality of standby sipping barrels in the process of performing inflation and drainage on the target sipping barrel, and respectively packaging other fuel assemblies to be detected into the standby sipping barrels;

step 104, after the target sipping tube is subjected to inflation and drainage treatment, performing background detection on the target sipping tube, and after the target sipping tube is subjected to background detection, performing vacuum radioactive detection on the target sipping tube to obtain a detection result;

step 105, after obtaining the detection result, performing an air washing process on a loop where the target sipping tube and the radioactive detector are located, lifting a fuel assembly in the target sipping tube, then performing an air washing process on the target sipping tube, packing a new fuel assembly to be detected into the target sipping tube, using the target sipping tube as a new standby sipping tube, and selecting a sipping tube from the original standby sipping tubes as a new target sipping tube;

step 106, repeating the operations from step 103 to step 105 for the new target sipping tube until the detection task is completed.

5. The method of claim 4, wherein selecting a sip canister from the existing sip canisters to be used as the new target sip canister comprises: selecting a target sip from the pending sippers that have never been tested, or that have been tested the least number of times.

6. The method of claim 4, wherein step 100 comprises:

opening the first gas source valve, each second vent valve, the first detection valve and the third detection valve to enable non-radioactive gas output by the gas source to continuously flush the radioactive detector, the radioactive detector associated pipeline and a device connected in series with the radioactive detector until the radioactivity level detected by the radioactive detector reaches a preset threshold value;

under the condition that the radioactivity level detected by the radioactivity detector reaches a preset threshold value, closing the first detection valve and the third detection valve, and opening each first ventilation valve within a preset time length to enable nonradioactive gas output by the gas source to continuously flush the upper pipeline of each sipping barrel;

and after the preset time, closing the first air source valve, each first ventilation valve and each second ventilation valve.

7. The method of claim 4, wherein step 101 comprises: opening the water inlet valve and the water outlet valve corresponding to the first water source valve and the target sipping barrel, and closing the water inlet valve and the water outlet valve corresponding to the target sipping barrel after the first water source continuously flushes the target sipping barrel for the preset time length.

8. The method of claim 4, wherein step 103 comprises: opening a first vent valve and a drain valve corresponding to the first water source valve, the first air source valve and the target sipping barrel, and a water inlet valve and a water outlet valve corresponding to each sipping barrel,

enabling the gas source to continuously convey gas to the target sipping barrel until the volume of liquid discharged by a water outlet valve of the target sipping barrel is detected to reach a preset threshold value, and closing a first gas source valve, a first ventilation valve corresponding to the target sipping barrel and the water outlet valve; and is

And after the first water source continuously washes the standby sipping cylinders for the preset time length, closing the water inlet valves and the water outlet valves corresponding to the standby sipping cylinders.

9. The method of claim 4, wherein the step of performing a vacuum radioactive assay on the target sipping tube comprises;

detecting a target sipping tube to obtain a detection result under the condition that a first vacuum degree is extracted through a vacuum pump;

if the obtained detection result is smaller than the detection threshold, repeatedly detecting the target sipping tube to obtain a detection result under the condition that the second vacuum degree is extracted through the vacuum pump, and taking the repeatedly obtained detection result as a final detection result.

10. The method of claim 4, further comprising:

and under the condition that the detection task is completed, opening the first water source valve, the water inlet valve and the water outlet valve of each sipping barrel, and flushing each sipping barrel through the first water source.

Technical Field

The invention belongs to the technical field of nuclear power maintenance, and particularly relates to a vacuum off-line sipping system and a detection method.

Background

The fuel assembly of the nuclear power plant is in a high-temperature, high-pressure and strong-irradiation environment for a long time, and the thin-wall cladding structure of the fuel rod is damaged or the material performance is degraded under the action of thermal stress, thermal expansion, irradiation damage and the like, so that the fuel assembly is damaged. Fuel assemblies produce a variety of fission products after a chain fission reaction is completed. When the fuel assembly is broken, fission products are released from the breach, and some fission gases such as Xe-133 and Kr-85 are insoluble in water.

In order to avoid reloading the damaged fuel assemblies into the reactor and affecting the core safety, the suspected damaged fuel assemblies must be sipped offline during a refueling overhaul, screened and isolated in time, and thus the accuracy of sipping detection is highly required. Meanwhile, if the detection time is too long, the overhaul process can be delayed, and the economic benefit of the power plant is influenced, so that the detection efficiency is also an important factor. Generally, fuel assembly offline sipping detection is a multi-step process of fuel preparation, constructing an environment to be detected, detection, resetting the environment after detection, and the preparation time before and after detection generally accounts for about 85% of the overall time. Meanwhile, the detection loop, sipping tube and the like have the risk of radioactive contamination after being used, and the detection precision is easily influenced, so that the reconstruction of the environment to be detected is complex, and more time is consumed.

In view of this, how to efficiently implement offline sipping detection of the fuel assembly becomes an urgent technical problem to be solved.

Disclosure of Invention

To overcome the problems in the related art, a vacuum offline sipping system and a detection method are provided.

According to an aspect of embodiments of the present disclosure, there is provided a vacuum offline sipping system, comprising: the system comprises a plurality of sipping barrels, a gas source, a first water source, a vacuum pump, a radioactivity detector, a spent water pool and an exhaust gas discharge system, wherein the gas source is used for outputting non-radioactive gas, and the first water source is used for conveying water;

the first vent of each sip tube is connected to the first connection point through a first vent valve, and the second vent of each sip tube is connected to the second connection point through a second vent valve;

the first connecting point is connected with a third connecting point through a first air source valve, the second connecting point is connected with the third connecting point through a second air source valve, and the third connecting point is connected with the air source;

the water inlet of each sipping barrel is connected with the fourth connection point through a water inlet valve, the water outlet of each sipping barrel is connected with the spent pool through a water outlet valve, and each water outlet valve can discharge the liquid of the sipping barrel connected with the sipping barrel to the spent pool;

the fourth connection point is connected with the first water source through a first water source valve;

the first connecting point is also connected with the vacuum pump through a first detection valve, the vacuum pump is connected with the radioactivity detector, and the radioactivity detector is connected with the exhaust emission system through a second detection valve;

the second connection point is connected between the radiation detector and the second detection valve by a third detection valve.

In one possible implementation, the vacuum offline sipping system further includes: a gas pretreatment device;

the gas pretreatment device is connected between the first detection valve and the vacuum pump.

In one possible implementation, the vacuum offline sipping system further includes: a second water source for outputting non-radioactive boric acid water, and the first water source for outputting boric acid water;

the fourth connection point is connected to the second water supply via a second water supply valve.

According to another aspect of the embodiments of the present disclosure, there is provided a detection method applied in the above-mentioned vacuum offline sipping system, the method comprising:

step 100, performing loop gas purging on the vacuum off-line sipping system;

step 101, after performing loop gas flushing on the vacuum off-line sipping system, selecting a sipping tube from the plurality of sipping tubes as a target sipping tube, using the remaining sipping tube as a standby sipping tube, and performing water flushing on the target sipping tube;

step 102, after the target sipping tube is subjected to water washing treatment, encapsulating the fuel assembly to be detected into the target sipping tube;

step 103, performing inflation and drainage treatment on the target sipping barrel after the water replacement treatment, flushing a plurality of standby sipping barrels in the process of performing inflation and drainage on the target sipping barrel, and respectively packaging other fuel assemblies to be detected into the standby sipping barrels;

step 104, after the target sipping tube is subjected to inflation and drainage treatment, performing background detection on the target sipping tube, and after the target sipping tube is subjected to background detection, performing vacuum radioactive detection on the target sipping tube to obtain a detection result;

step 105, after obtaining the detection result, performing an air washing process on a loop where the target sipping tube and the radioactive detector are located, lifting a fuel assembly in the target sipping tube, then performing an air washing process on the target sipping tube, packing a new fuel assembly to be detected into the target sipping tube, using the target sipping tube as a new standby sipping tube, and selecting a sipping tube from the original standby sipping tubes as a new target sipping tube;

step 106, repeating the operations from step 103 to step 105 for the new target sipping tube until the detection task is completed.

In one possible implementation, selecting a sip canister from the original standby sip canisters as a new target sip canister includes: selecting a target sip from the pending sippers that have never been tested, or that have been tested the least number of times.

In one possible implementation, step 100 includes:

opening the first gas source valve, each second vent valve, the first detection valve and the third detection valve to enable non-radioactive gas output by the gas source to continuously flush the radioactive detector, the radioactive detector associated pipeline and a device connected in series with the radioactive detector until the radioactivity level detected by the radioactive detector reaches a preset threshold value;

under the condition that the radioactivity level detected by the radioactivity detector reaches a preset threshold value, closing the first detection valve and the third detection valve, and opening each first ventilation valve within a preset time length to enable nonradioactive gas output by the gas source to continuously flush the upper pipeline of each sipping barrel;

and after the preset time, closing the first air source valve, each first ventilation valve and each second ventilation valve.

In one possible implementation, step 101 includes: opening the water inlet valve and the water outlet valve corresponding to the first water source valve and the target sipping barrel, and closing the water inlet valve and the water outlet valve corresponding to the target sipping barrel after the first water source continuously flushes the target sipping barrel for the preset time length.

In one possible implementation, step 103 includes: opening a first vent valve and a drain valve corresponding to the first water source valve, the first air source valve and the target sipping barrel, and a water inlet valve and a water outlet valve corresponding to each sipping barrel,

enabling the gas source to continuously convey gas to the target sipping barrel until the volume of liquid discharged by a water outlet valve of the target sipping barrel is detected to reach a preset threshold value, and closing a first gas source valve, a first ventilation valve corresponding to the target sipping barrel and the water outlet valve; and is

And after the first water source continuously washes the standby sipping cylinders for the preset time length, closing the water inlet valves and the water outlet valves corresponding to the standby sipping cylinders.

In one possible implementation, performing vacuum radioactive detection on the target sipping tube to obtain a detection result, including;

detecting a target sipping tube to obtain a detection result under the condition that a first vacuum degree is extracted through a vacuum pump;

if the obtained detection result is smaller than the detection threshold, repeatedly detecting the target sipping tube to obtain a detection result under the condition that the second vacuum degree is extracted through the vacuum pump, and taking the repeatedly obtained detection result as a final detection result.

In one possible implementation, the method further includes:

and under the condition that the detection task is completed, opening the first water source valve, the water inlet valve and the water outlet valve of each sipping barrel, and flushing each sipping barrel through the first water source.

The invention has the beneficial effects that: the detection method disclosed by the invention realizes the time-sharing synchronous alternative detection of multiple sipping tubes on the premise of ensuring the detection accuracy, and shortens the detection time. The time for average detecting a group of fuel groups is shortened by more than 30% by adopting a method of sip alternation detection. In addition, due to the design of a plurality of sipping tubes, the alternate detection work of the double sipping tubes can be realized, the independent detection work of the single sipping tube can also be realized, and the redundancy of the system is improved.

Drawings

Fig. 1 is a schematic diagram illustrating a vacuum offline sipping system, according to an example embodiment.

Detailed Description

The invention is described in further detail below with reference to the figures and the embodiments.

An embodiment of the present disclosure provides a vacuum offline sipping system, including: the system comprises a plurality of sipping barrels, a gas source, a first water source, a vacuum pump, a radioactivity detector, a spent water pool and an exhaust gas discharge system, wherein the gas source is used for outputting non-radioactive gas, and the first water source is used for conveying water;

the first vent of each sip tube is connected to the first connection point through a first vent valve, and the second vent of each sip tube is connected to the second connection point through a second vent valve;

the first connecting point is connected with a third connecting point through a first air source valve, the second connecting point is connected with the third connecting point through a second air source valve, and the third connecting point is connected with the air source;

the water inlet of each sipping barrel is connected with the fourth connection point through a water inlet valve, the water outlet of each sipping barrel is connected with the spent pool through a water outlet valve, and each water outlet valve can discharge the liquid of the sipping barrel connected with the sipping barrel to the spent pool;

the fourth connection point is connected with the first water source through a first water source valve;

the first connecting point is also connected with the vacuum pump through a first detection valve, the vacuum pump is connected with the radioactivity detector, and the radioactivity detector is connected with the exhaust emission system through a second detection valve;

the second connection point is connected between the radiation detector and the second detection valve by a third detection valve.

The vacuum off-line sipping detection of the fuel assembly is that the fuel assembly to be detected is hung into a container (sipping barrel) capable of realizing an underwater sealing function, a detection environment of the fuel assembly to be detected is established, negative pressure is generated in the container through loop control to promote release of radioactive fission gas in a damaged fuel assembly, finally, the activity of the released fission gas is detected through a set of high-precision radioactive detectors, and whether the fuel assembly to be detected is damaged or not is judged.

Fig. 1 is a schematic diagram illustrating a vacuum offline sipping system, according to an example embodiment. As shown in fig. 1, the vacuum offline sipping system includes 2 sipping barrels 18, the first vent of each sipping barrel 18 is connected to the first connection point through a first vent valve V1, and the second vent of each sipping barrel 18 is connected to the second connection point through a second vent valve V2;

the first connecting point is connected with a third connecting point through a first air source valve V002, the second connecting point is connected with the third connecting point through a second air source 14 valve V001, and the third connecting point is connected with the air source 14;

the inlet of each sip barrel 18 is connected to the fourth connection point through an inlet valve V3, the outlet of each sip barrel 18 is connected to the spent pool 17 through an outlet valve V4, and each outlet valve V4 is capable of draining the liquid of the sip barrel 18 connected thereto to the spent pool 17;

the fourth connection point is connected to the first water supply 15 via a first water supply 15 valve;

the first connection point is further connected with the vacuum pump 11 through a first detection valve V007, the vacuum pump 11 is connected with the radioactivity detector 12, and the radioactivity detector 12 is connected with the exhaust emission system 13 through a second detection valve V006;

the second connection point is connected between the radioactivity detector 12 and the second detection valve V006 via a third detection valve V005.

It should be noted that, the number of sip tubes may be selected as needed, and the number of sip tubes is not limited in the embodiments of the present disclosure.

In one possible implementation, as shown in fig. 1, the vacuum offline sipping system further includes: the gas pretreatment device 10 is connected between the first detection valve V007 and the vacuum pump 11, and the gas pretreatment device 10 can effectively filter impurities in gas input into the vacuum pump and effectively reduce the damage of the impurities in the gas to the vacuum pump and the radioactive detector.

In one possible implementation, as shown in fig. 1, the vacuum offline sipping system further includes: a second water source 16, the second water source 16 capable of outputting non-radioactive boric acid water; the first water source 15 is capable of outputting boric acid water (e.g., the first water source may take water from a spent fuel pool, the disclosure does not require the radioactivity of the boric acid water of the first water source). The fourth connection point is connected to a second water supply 16 via a second water supply valve V004. For example, when the procedure of flushing impurities with a large amount of water is performed, the first water source 15 may be used to flush the impurities in the sipping barrel 18, and then the second water source 16 may be used to flush the sipping barrel 18 with non-radioactive boric acid solution to perform the water replacement process, so as to discharge the radioactive residues, thereby reducing the amount of non-radioactive boric acid solution used.

In one possible implementation, a method for detecting a sip is provided, where the method is applicable to the vacuum offline sipping system, and the method includes:

step 100, performing loop gas purging on the vacuum off-line sipping system;

as shown in fig. 1, step 100 may include:

opening a first gas source valve V002, each second vent valve V2, a first detection valve V007 and a third detection valve V005 to enable nonradioactive gas output by a gas source 14 to continuously flush the radioactive detector 12, pipelines associated with the radioactive detector 12 and devices (such as a vacuum pump 11, a gas pretreatment device and the like) connected in series with the radioactive detector 12, wherein the radioactivity level of the passing gas can be detected by the radioactive detector 12 in the gas flushing process, the first detection valve V007 and the third detection valve V005 can be closed under the condition that the radioactivity level detected by the radioactive detector 12 reaches a preset threshold value, and each first vent valve V1 is opened within a preset time length to enable nonradioactive gas output by the gas source 14 to continuously flush the upper pipelines of each sipping barrel 18; after a predetermined period of time, the first gas supply valve V002, and the first vent valves V1 are closed. It should be noted that, in the embodiment of the present disclosure, each valve may be in a normally closed state, and the corresponding valve may be opened according to the requirement of the process flow at each stage, and the corresponding valve may be closed after the process flow is finished.

Step 101, after performing loop gas flushing on the vacuum off-line sipping system, selecting a sipping tube from the plurality of sipping tubes as a target sipping tube, using the remaining sipping tube as a standby sipping tube, and performing water flushing on the target sipping tube;

for example, as shown in fig. 1, the left sip barrel 18 may be selected as the target sip barrel 18 and the right sip barrel 18 may be selected as the standby sip barrel 18, and then the first water source valve V003, the inlet valve V3 corresponding to the target sip barrel 18, and the outlet valve V4 may be opened to let the first water source 15 flush the target sip barrel 18 for the preset length of time, and then the inlet valve V3 and the outlet valve V4 corresponding to the target sip barrel 18 may be closed.

Step 102, after the water flush treatment of the target sip, encapsulates the fuel assembly to be examined into the target sip, and may, for example, perform a sealing and water replacement treatment on the target sip to expel the original radioactive water from the target sip.

For example, as shown in fig. 1, the second water source valve V004, the inlet valve V3 and the outlet valve V4 corresponding to the target sipping barrel 18 may be opened. Injecting non-radioactive boric acid water into the target sipping tube 18, discharging the original radioactive water dissolved in the target sipping tube 18, and discharging the discharged waste water into the spent water pool 17. In one possible implementation, the volume of the water injected during the target sipping procedure is at least 2 times the volume of the sipping tube, so as to more completely remove the radioactive material in the target sipping tube.

Step 103, performing inflation and drainage treatment on the target sipping barrel after the water replacement treatment, flushing a plurality of standby sipping barrels in the process of performing inflation and drainage on the target sipping barrel, and respectively packaging other fuel assemblies to be detected into the standby sipping barrels;

as shown in fig. 1, step 103 includes: opening the first water source valve V003, the first air source valve V002, the first vent valve V1 and the exit valve V4 corresponding to the target sip barrel 18, and using the entrance valve V3 and the exit valve V4 corresponding to the target sip barrel 18,

continuing to infuse the gas source 14 to the target sip barrel 18 until the volume of liquid discharged from the exit valve V4 of the target sip barrel 18 reaches the preset threshold, and closing the first gas source valve V002, the first vent valve V1 and the exit valve V4 corresponding to the target sip barrel 18.

During the process of infusing the target sip barrel 18, the first water source 15 may be enabled to continuously flush the standby sip barrel 18 for a preset duration, and after the preset duration, the inlet valve V3 and the outlet valve V4 corresponding to the standby sip barrel 18 may be closed. Enclosing a ready-to-use fuel assembly into the standby sipping barrel 18.

In a possible implementation, during the sipping of the target sip, the first water source valve, the inlet valve and the outlet valve corresponding to the standby sipping may be opened, such that the first water source flushes the standby sipping for a predetermined duration, the first water source valve is closed, and a fuel assembly to be examined is encapsulated in the standby sipping. And then opening a second water source valve to inject the second water source non-radioactive water source into the sipping tube to be used, discharging the original radioactive water dissolved in the sipping tube to be used, and discharging the discharged wastewater into the spent water pool.

Step 104, after the target sipping tube is subjected to inflation and drainage treatment, performing background detection on the target sipping tube, and after the target sipping tube is subjected to background detection, performing vacuum radioactive detection on the target sipping tube to obtain a detection result;

as shown in fig. 1, second gas source 14 valve V001, first vent valve V1 and second vent valve V2 corresponding to target sipping barrel 18, first detection valve V007, second detection valve V006, and third detection valve V005 may be opened, external non-radioactive compressed gas source 14 is introduced for a preset ventilation duration, radioactivity K0 detected by radioactivity detector 12 after the preset ventilation duration may be recorded, and then second gas source 14 valve V001, first vent valve V1 and second vent valve V2 corresponding to target sipping barrel 18, first detection valve V007, second detection valve V006, and third detection valve V005 may be closed.

Next, the target sipping barrel 18 may be vacuumed: the first detection valve V007 and the first vent valve V1 corresponding to the target sip 18 may be opened, the vacuum pump 11 may be turned on, the gas pressure of the target sip 18 may be obtained until the gas pressure in the sip 18 reaches a predetermined value, and the vacuum pump 11 may be turned off.

A loop check of the target sipping barrel 18 may then be performed. The third detection valve V005 and the second vent valve V2 corresponding to the target sipping barrel 18 can be opened, and the radioactivity level at this time can be cyclically detected by the radioactivity detector 12 until the radioactivity value is stable, and then the radioactivity K1 can be recorded. And calculating a ratio M of K1 to K0, wherein when M is larger than or equal to a preset threshold value M0, the current detected fuel assembly is damaged, and when the size of M is lower than a preset threshold value M0, the current detected fuel assembly is not damaged.

When M is less than M0, the first detection valve V007 and the first vent valve V1 corresponding to the target sip 18 may be opened, the vacuum pump 11 may be turned on, the gas pressure of the target sip 18 may be obtained, and the vacuum pump 11 may be turned off until the vacuum degree of the target sip 18 is less than the vacuum degree of the previous vacuum. A lower vacuum is drawn by the vacuum pump 11 to further facilitate the release of radioactive gas from suspected damaged fuel assemblies. And performing cycle detection of the loop of the target sipping barrel 18 again, and detecting to obtain the radioactivity K2. If there is no significant increase in K2 relative to K1 (e.g., the difference between K2 and K1 is less than a predetermined threshold), it is an indication that the fuel assembly under test is not damaged, and if there is a significant increase in K2 relative to K1 (the difference between K2 and K1 is greater than a predetermined threshold), it is damaged. Therefore, the occurrence of missing detection can be effectively avoided.

Step 105, after obtaining the detection result, performing an air washing process on a loop where the target sipping tube and the radioactive detector are located, lifting a fuel assembly in the target sipping tube, then performing an air washing process on the target sipping tube, packaging a new fuel assembly to be detected into the target sipping tube, performing a water replacement process, using the target sipping tube as a new standby sipping tube, and selecting a sipping tube from the original standby sipping tubes as a new target sipping tube;

for example, as shown in fig. 1, the target sipping canister 18 may be first vented to the detection circuit: and (3) opening a valve V1 and a second vent valve V2 of the second gas source 14, and a first detection valve V007 and a second detection valve V006 corresponding to the target sipping barrel 18, introducing an external nonradioactive compressed gas source 14, discharging radioactive gas possibly existing in a detection loop until the radioactivity detected by the radioactive detector 12 meets a preset threshold, and closing the valve V001 of the second gas source 14, the first vent valve V1 and the second vent valve V2 of the target sipping barrel 18, and the first detection valve V007 and the second detection valve V006.

The target sipping canister 18 is opened and the detected fuel assemblies are hoisted away from the target sipping canister 18 using on-site hoisting equipment.

Next, the target sipping barrel 18 may be loop air flushed: opening a first gas source valve V002, a second vent valve V2, a first detection valve V007 and a third detection valve V005 corresponding to the target sipping barrel 18, so that the radioactivity-free gas output by the gas source 14 continuously washes the radioactive detector 12, the pipeline associated with the radioactive detector 12 and the device (such as the vacuum pump 11, the gas pretreatment device and the like) connected in series with the radioactive detector 12, wherein the radioactivity level of the passing gas is detected by the radioactive detector 12 during the gas washing process, the first detection valve V007 and the third detection valve V005 are closed when the radioactivity level detected by the radioactive detector 12 reaches a preset threshold, and the first vent valve V1 corresponding to the target sipping barrel 18 is opened within a preset time period, so that the radioactivity-free gas output by the gas source 14 continuously washes the upper pipeline of each sipping barrel 18; after a preset duration, the first gas source valve V002, and the first vent valve V1 and the second vent valve V2 corresponding to the target sip canister 18 are closed.

After performing the loop gas flush on the target sip canister 18, and then performing the water flush on the target sip canister 18, the target sip canister 18 is then filled with a new fuel assembly to be examined, and a water replacement process is performed.

The target sip 18 may be used as a new standby sip 18, the original standby sip 18 may be used as a new target sip 18;

step 106, repeating the operations from step 103 to step 105 for the new target sipping tube until the detection task is completed.

And finally, under the condition that the detection task is completed, opening the first water source valve, the water inlet valve and the water outlet valve of each sipping barrel, introducing the demineralized water from the first water source valve, and flushing each sipping barrel so as to avoid the boric acid water from crystallizing in each sipping barrel.

In one possible implementation, selecting a sip canister from the original standby sip canisters as a new target sip canister includes: selecting a target sip from the pending sippers that have never been tested, or that have been tested the least number of times.

The detection method disclosed by the invention realizes the time-sharing synchronous alternative detection of multiple sipping tubes on the premise of ensuring the detection accuracy, and shortens the detection time. The time for average detecting a group of fuel groups is shortened by more than 30% by adopting a method of sip alternation detection. In addition, due to the design of a plurality of sipping tubes, the alternate detection work of the double sipping tubes can be realized, the independent detection work of the single sipping tube can also be realized, and the redundancy of the system is improved.

Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein were chosen in order to best explain the principles of the embodiments, the practical application, or technical improvements to the techniques in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.