A method and apparatus for decoction and cleaning of hexagonal nuclear fuel assemblies in pressurized water reactors

Abstract

This invention relates to the field of nuclear fuel element manufacturing, and more particularly to a method and apparatus for defilming and cleaning hexagonal nuclear fuel assemblies for pressurized water reactors. The method involves: defilming the hexagonal nuclear fuel assembly in deionized water, followed by cleaning and rinsing in deionized water; and finally, rinsing and drying the fuel assembly. The apparatus includes: deionized water pipes connected to the tops of a defilming tank, a cleaning tank, and a rinsing tank; spray devices installed on the side walls of the defilming tank, cleaning tank, and rinsing tank; and a control cabinet controlling the injection volume of deionized water, drying temperature, drying time, spraying time, and airflow. This invention effectively removes zirconium shavings and surface films from the nuclear fuel assembly, and is safe and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of nuclear fuel element manufacturing, and in particular to a method and apparatus for defilming and cleaning hexagonal nuclear fuel assemblies for pressurized water reactors. Background Technology

[0002] Nuclear fuel assemblies are the core components of a nuclear power plant reactor, and foreign objects on their surface can affect the safe operation of the reactor. These fuel assemblies are characterized by high burnup and long operating cycles. The fuel rods are coated with a polyvinyl alcohol solution. When the coated fuel rods are pushed into the grid using a pusher method, the surface of the coated rod comes into contact with and rubs against the grid cells, inevitably scratching the fuel rod coating and generating zirconium shavings on the fuel rod surface or within the grid cells. Experience has shown that zirconium shavings are one of the significant causes of fuel assembly damage during reactor operation.

[0003] Traditional methods of cleaning nuclear fuel assemblies using NaOH aqueous solution and deionized water result in waste liquid that has a certain environmental impact. Other methods of removing foreign matter, such as blowing, can remove some zirconium shavings, but the surface film still adheres to the fuel rods. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and apparatus for defilming and cleaning hexagonal nuclear fuel assemblies of pressurized water reactors, which effectively removes foreign matter such as zirconium chips and surface films from the nuclear fuel assemblies in a safe and environmentally friendly manner.

[0005] This invention provides a method for defilming and cleaning hexagonal nuclear fuel assemblies in a pressurized water reactor, comprising the following steps:

[0006] Step 1: Prepare the demolding solution, insert the guide tube of the pressurized water reactor hexagonal nuclear fuel assembly into the plug, and then immerse it in the demolding solution for demolding; use the cleaning solution to clean the pressurized water reactor hexagonal nuclear fuel assembly;

[0007] The method for preparing the release liquid is as follows: heat deionized water to 90-100°C, introduce dry, oil-free compressed air, and bubble; the release liquid is the same as the cleaning liquid.

[0008] Step 2: Rinse the hexagonal nuclear fuel assemblies of the pressurized water reactor using rinsing fluid;

[0009] The rinsing solution is prepared by heating deionized water to 90-100°C, introducing dry, oil-free compressed air, and bubbling.

[0010] Step 3: Rinse with deionized water at 90-100℃;

[0011] Step 4: Wipe the surface of the pressurized water reactor hexagonal nuclear fuel assembly with a dry, clean coarse cotton cloth. If there are stains, return to Step 1. If there are no stains, continue to Step 5.

[0012] Step 5: Remove the plug from the guide tube of the pressurized water reactor hexagonal nuclear fuel assembly and dry it;

[0013] Step 6: Use a deburring tool to remove zirconium shavings and nodules from the fuel rods and grid cells. Use high-pressure nitrogen or filtered, dried, oil-free compressed air to purge from all six sides of the pressurized water reactor hexagonal nuclear fuel assembly. Purge each layer of fuel rods until there are no visible zirconium shavings on the fuel rods and grid cells.

[0014] In one specific embodiment of the present invention, in step one, the demolding time is not less than 20 seconds.

[0015] In one specific embodiment of the present invention, the cleaning time in step one is not less than 5 seconds.

[0016] In one specific embodiment of the present invention, in step two, the rinsing time is not less than 20 seconds.

[0017] In one specific embodiment of the present invention, in step five, hot air is used for drying.

[0018] In one specific embodiment of the present invention, the temperature of the hot air is 60-80°C.

[0019] In one specific embodiment of the present invention, the drying time is not less than 60 minutes.

[0020] This invention provides an apparatus for defilming and cleaning hexagonal nuclear fuel assemblies in pressurized water reactors, comprising:

[0021] Rinse-off device, deionized water pipeline, control cabinet, demolding tank, cleaning tank, rinsing tank, drying tank, jet blowing device;

[0022] The deionized water pipes are connected to the top of the stripping tank, the cleaning tank, and the rinsing tank, respectively.

[0023] Spraying devices are provided on the side walls of the stripping tank, washing tank, and rinsing tank.

[0024] The control cabinet controls the injection volume of deionized water, drying temperature, drying time, blowing time, and air volume.

[0025] Compared with existing technologies, the method and apparatus for demolding and cleaning hexagonal nuclear fuel assemblies of pressurized water reactors of the present invention can effectively remove foreign matter such as zirconium shavings and surface films from the nuclear fuel assembly, and the surface quality of the fuel assembly after demolding and cleaning meets expectations. Moreover, deionized water is used for demolding and cleaning, without adding other alkaline substances, reducing the environmental impact of the cleaning waste liquid. Attached Figure Description

[0026] Figure 1A schematic diagram showing the structure of a hexagonal nuclear fuel assembly stripping and cleaning device for a pressurized water reactor;

[0027] In the diagram, 1-spraying device, 2-deionization pipeline, 3-control cabinet, 4-demolding tank, 5-washing tank, 6-rinsing tank, 7-drying tank, 8-blowing device. Detailed Implementation

[0028] To further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0029] An embodiment of the present invention discloses a method for defilming and cleaning a hexagonal nuclear fuel assembly in a pressurized water reactor, comprising the following steps:

[0030] Step 1: Prepare the demolding solution. After inserting the guide tube of the pressurized water reactor hexagonal nuclear fuel assembly into the plug, immerse it in the demolding solution for demolding. The demolding time shall not be less than 20 seconds.

[0031] The method for preparing the release liquid is as follows: heat deionized water to 90-100°C, introduce dry, oil-free compressed air, and bubble.

[0032] The hexagonal nuclear fuel assembly of the pressurized water reactor is cleaned with a cleaning fluid for no less than 5 seconds.

[0033] The stripping solution is the same as the cleaning solution;

[0034] Step 2: Rinse the pressurized water reactor hexagonal nuclear fuel assembly with rinsing fluid for no less than 20 seconds;

[0035] The rinsing solution is prepared by heating deionized water to 90-100°C, introducing dry, oil-free compressed air, and bubbling.

[0036] Step 3: Rinse with deionized water at 90-100℃;

[0037] Step 4: Wipe the surface of the pressurized water reactor hexagonal nuclear fuel assembly with a dry, clean coarse cotton cloth. If there are stains, return to Step 1. If there are no stains, continue to Step 5.

[0038] Step 5: Remove the plug from the guide tube of the pressurized water reactor hexagonal nuclear fuel assembly and dry it;

[0039] Drying is performed using hot air;

[0040] The temperature of the hot air is 60-80°C, and the drying time is no less than 60 minutes.

[0041] Step 6: Use a deburring tool to remove zirconium shavings and nodules from the fuel rods and grid cells. Use high-pressure nitrogen or filtered, dried, oil-free compressed air to purge from all six sides of the pressurized water reactor hexagonal nuclear fuel assembly. Purge each layer of fuel rods until there are no visible zirconium shavings on the fuel rods and grid cells.

[0042] After cleaning the components, inspect the surface of the fuel assembly; there should be no visible zirconium shavings or other foreign matter.

[0043] An embodiment of the present invention discloses an apparatus for defilming and cleaning hexagonal nuclear fuel assemblies in pressurized water reactors, such as... Figure 1 As shown, it includes:

[0044] 1. Rinse device; 2. Deionized water pipeline; 3. Control cabinet; 4. Demolding tank; 5. Cleaning tank; 6. Rinse tank; 7. Drying tank; 8. Spray blowing device.

[0045] The deionized water pipe 2 is connected to the top of the stripping tank 3, the cleaning tank 4, and the rinsing tank 5 respectively;

[0046] Spraying devices 1 are provided on the side walls of the demolding tank 3, the washing tank 4, and the rinsing tank 5.

[0047] Control cabinet 3 controls the injection volume of deionized water, drying temperature, drying time, blowing time, and air volume.

[0048] To further understand the present invention, the method and apparatus for defilming and cleaning hexagonal nuclear fuel assemblies of pressurized water reactors provided by the present invention will be described in detail below with reference to embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0049] Example 1

[0050] Step 1: In Figure 1 Deionized water was added to the demolding tank and heated to 95°C. Dry, oil-free compressed air was introduced, and bubbles were formed. After inserting the 18 guide tubes of the assembly into the plug, it was lowered into the cleaning tank. The demolding time was 20 seconds. The demolding solution was drained. Deionized water was added again, heated to 95°C, and dry, oil-free compressed air was introduced, and bubbles were formed. The cleaning time was 5 seconds. Finally, it was rinsed and then lifted out.

[0051] Step Two: In Figure 1 Add deionized water to the cleaning tank, heat to 95°C, and then introduce dry, oil-free compressed air bubbles for 20 seconds. Drain the rinsing water.

[0052] Step 3: In Figure 1 Deionized water at 95°C is injected into the rinsing tank, and the components are rinsed when they are lifted.

[0053] Step 4: Wipe the surface of the pressurized water reactor hexagonal nuclear fuel assembly with a dry, clean coarse cotton cloth. If there are stains, return to Step 1. If there are no stains, continue to Step 5.

[0054] Step 5: Remove the plugs from the 18 guide tubes of the component, lower them into the drying chamber, close and secure the cover, and introduce hot air into the drying chamber for drying. When the hot air temperature is 60℃, the drying time is 70 minutes.

[0055] Step Six: Hoist the fuel assembly to the injection unit. During the descent of the fuel assembly, use a deburring tool to remove zirconium shavings and nodules from the fuel rods and grid elements. During the lifting of the fuel assembly, use high-pressure nitrogen or filtered, dried, oil-free compressed air to blow the fuel rods and grid from all six sides of the fuel assembly. Each layer of fuel rods must be blown until no visible zirconium shavings are visible on the fuel rods and grid.

[0056] Example 2

[0057] Step 1: In Figure 1 Deionized water was added to the demolding tank and heated to 98°C. Dry, oil-free compressed air was introduced, and bubbles were formed. After inserting the 18 guide tubes of the assembly into the plug, it was lowered into the cleaning tank. The demolding time was 30 seconds. The demolding solution was drained. Deionized water was added again, heated to 98°C, and dry, oil-free compressed air was introduced, and bubbles were formed. The cleaning time was 10 seconds. Finally, it was rinsed and then lifted out.

[0058] Step Two: In Figure 1 Add deionized water to the cleaning tank, heat to 98°C, and then introduce dry, oil-free compressed air bubbles for 30 seconds. Drain the rinsing water.

[0059] Step 3: In Figure 1 Deionized water at 98°C is injected into the rinsing tank, and the components are rinsed when they are lifted.

[0060] Step 4: Wipe the surface of the pressurized water reactor hexagonal nuclear fuel assembly with a dry, clean coarse cotton cloth. If there are stains, return to Step 1. If there are no stains, continue to Step 5.

[0061] Step 5: Remove the plugs from the 18 guide tubes of the component, lower them into the drying chamber, close and secure the cover, and introduce hot air into the drying chamber for drying. When the hot air temperature is 70℃, the drying time is 70 minutes.

[0062] Step Six: Hoist the fuel assembly to the injection unit. During the descent of the fuel assembly, use a deburring tool to remove zirconium shavings and nodules from the fuel rods and grid elements. During the lifting of the fuel assembly, use high-pressure nitrogen or filtered, dried, oil-free compressed air to blow the fuel rods and grid from all six sides of the fuel assembly. Each layer of fuel rods must be blown until no visible zirconium shavings are visible on the fuel rods and grid.

[0063] Example 3

[0064] Step 1: In Figure 1 Deionized water was added to the demolding tank and heated to 93°C. Dry, oil-free compressed air was introduced, and bubbles were formed. After inserting the 18 guide tubes of the assembly into the plug, it was lowered into the cleaning tank. The demolding time was 30 seconds. The demolding solution was drained. Deionized water was added again, heated to 93°C, and dry, oil-free compressed air was introduced, and bubbles were formed. The cleaning time was 10 seconds. Finally, it was rinsed and lifted out.

[0065] Step Two: In Figure 1 Add deionized water to the cleaning tank, heat to 93°C, and introduce dry, oil-free compressed air bubbles for 30 seconds. Drain the rinsing water.

[0066] Step 3: In Figure 1 Deionized water at 93°C is injected into the rinsing tank, and the components are rinsed when they are lifted.

[0067] Step 4: Wipe the surface of the pressurized water reactor hexagonal nuclear fuel assembly with a dry, clean coarse cotton cloth. If there are stains, return to Step 1. If there are no stains, continue to Step 5.

[0068] Step 5: Remove the plugs from the 18 guide tubes of the component, lower them into the drying chamber, close and secure the cover, and introduce hot air into the drying chamber for drying. When the hot air temperature is 80℃, the drying time is 60 minutes.

[0069] Step Six: Hoist the fuel assembly to the injection unit. During the descent of the fuel assembly, use a deburring tool to remove zirconium shavings and nodules from the fuel rods and grid elements. During the lifting of the fuel assembly, use high-pressure nitrogen or filtered, dried, oil-free compressed air to blow the fuel rods and grid from all six sides of the fuel assembly. Each layer of fuel rods must be blown until no visible zirconium shavings are visible on the fuel rods and grid.

[0070] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0071] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for decoction and cleaning of hexagonal nuclear fuel assemblies in a pressurized water reactor, characterized in that, Includes the following steps: Step 1: Prepare the demolding solution, insert the guide tube of the pressurized water reactor hexagonal nuclear fuel assembly into the plug, and then immerse it in the demolding solution for demolding; use the cleaning solution to clean the pressurized water reactor hexagonal nuclear fuel assembly; The method for preparing the release liquid is as follows: heat deionized water to 90-100°C, introduce dry, oil-free compressed air, and bubble; the release liquid is the same as the cleaning liquid. Step 2: Rinse the hexagonal nuclear fuel assemblies of the pressurized water reactor using rinsing fluid; The rinsing solution is prepared by heating deionized water to 90-100°C, introducing dry, oil-free compressed air, and bubbling. Step 3: Rinse with deionized water at 90-100℃; Step 4: Wipe the surface of the pressurized water reactor hexagonal nuclear fuel assembly with a dry, clean coarse cotton cloth. If there are stains, return to Step 1. If there are no stains, continue to Step 5. Step 5: Remove the plug from the guide tube of the pressurized water reactor hexagonal nuclear fuel assembly and dry it; Step 6: Use a deburring tool to remove zirconium shavings and nodules from the fuel rods and grid cells. Use high-pressure nitrogen or filtered, dried, oil-free compressed air to purge from all six sides of the pressurized water reactor hexagonal nuclear fuel assembly. Purge each layer of fuel rods until there are no visible zirconium shavings on the fuel rods and grid cells.

2. The method for defilming and cleaning hexagonal nuclear fuel assemblies in a pressurized water reactor according to claim 1, characterized in that, In step one, the demolding time shall be no less than 20 seconds.

3. The method for defilming and cleaning hexagonal nuclear fuel assemblies in a pressurized water reactor according to claim 1, characterized in that, In step one, the cleaning time shall be no less than 5 seconds.

4. The method for defilming and cleaning hexagonal nuclear fuel assemblies in a pressurized water reactor according to claim 1, characterized in that, In step two, the rinsing time shall be no less than 20 seconds.

5. The method for defilming and cleaning hexagonal nuclear fuel assemblies in a pressurized water reactor according to claim 1, characterized in that, In step five, hot air is used for drying.

6. The method for defilming and cleaning hexagonal nuclear fuel assemblies in a pressurized water reactor according to claim 5, characterized in that, The temperature of the hot air is 60–80°C.

7. The method for defilming and cleaning hexagonal nuclear fuel assemblies in a pressurized water reactor according to claim 6, characterized in that, The drying time shall be no less than 60 minutes.

8. A device for defilming and cleaning hexagonal nuclear fuel assemblies in a pressurized water reactor, characterized in that, include: Rinse-off device, deionized water pipeline, control cabinet, demolding tank, cleaning tank, rinsing tank, drying tank, jet blowing device; The deionized water pipes are connected to the top of the stripping tank, the cleaning tank, and the rinsing tank, respectively. Spraying devices are provided on the side walls of the stripping tank, washing tank, and rinsing tank. The control cabinet controls the injection volume of deionized water, drying temperature, drying time, blowing time, and air volume.

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