Extended replacement method for core thermocouple connectors

Abstract

The present disclosure belongs to the field of nuclear power technology, and specifically relates to a method for extending and replacing a core thermocouple connector. The disclosed extension method uses cold-pressed welding technology of the same material at the connection part between the new thermocouple and the old thermocouple to ensure the accuracy of the thermocouple measurement performance. The cold-pressed weld part is wrapped with a high-temperature radiation-resistant insulating material to prevent the two thermocouple wires from contacting each other and causing signal interference. The two thermocouples of the C1 core thermocouple were repaired by the extension method. After the repair, the insulation resistance values ​​returned to normal. After a cycle of verification, the core thermocouple function indication was normal.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power, and in particular relates to a method for extending and replacing a core thermocouple connector. Background Art

[0002] During online maintenance of thermocouples in pressurized water reactor nuclear power plants, if the thermocouple cannot be removed even after the extraction force exceeds a certain limit, it indicates that the thermocouple is stuck or stuck in the guide sleeve, making it impossible to replace the thermocouple. Once the thermocouple itself is confirmed to be in good condition, the thermocouple is repaired online. Because the thermocouples are concentrated in a cluster column, the workspace is confined, and due to high radiation doses and insufficient lighting, traditional repair methods are difficult to repair thermocouple connectors. Therefore, there is an urgent need to improve the repair efficiency of core thermocouples. Summary of the Invention

[0003] In order to overcome the problems existing in the related art, a method for extending and replacing a core thermocouple connector is provided.

[0004] According to one aspect of an embodiment of the present disclosure, a method for extending and replacing a core thermocouple connector is provided, the method comprising:

[0005] Step 100: selecting a new thermocouple made of the same material as the old thermocouple, selecting a new thermocouple connector of the same model as the old thermocouple connector, welding one end of the new thermocouple to the new thermocouple connector, and sealing and protecting them;

[0006] Step 101: Cut off the other end of the new thermocouple by a preset length, then polish the other end of the new thermocouple until the thermocouple wire is exposed, and determine the positive and negative poles of the exposed wire, so that the length of the positive wire is greater than the length of the negative wire.

[0007] Step 102: Cut off the old thermocouple connector and polish the old thermocouple at the cut portion until the old thermocouple filament is exposed. Then, determine the positive and negative poles of the filaments so that the length of the positive filament is shorter than the length of the negative filament.

[0008] Step 103, using a ferrule connector of the same model as the primary seal of the old thermocouple, and inserting the ferrule connector into the wire of the old thermocouple;

[0009] Step 104: contacting the positive wire of the new thermocouple with the positive wire of the old thermocouple, contacting the negative wire of the new thermocouple with the negative wire of the old thermocouple, isolating the positive wire and the negative wire with a high-temperature resistant insulating sheet, selecting an extension tube to surround the new thermocouple and the old thermocouple, and cold-pressing welding the new thermocouple and the old thermocouple using a nickel tube outside the extension tube;

[0010] Step 105, after the cold pressure welding is completed, the new thermocouple and the old thermocouple are filled with a filling material in the extension tube so that the new thermocouple and the old thermocouple are insulated and sealed from the outside world;

[0011] Step 106: Use a joint to fix the newly extended thermocouple.

[0012] In a possible implementation, the preset length may be between 30-40 cm.

[0013] In one possible implementation, the extension tube is a 3 / 8 Swagelok instrument line.

[0014] In a possible implementation, the filling material is epoxy resin or magnesium oxide powder.

[0015] In one possible implementation, the connector is a Swagelok connector.

[0016] The beneficial effects of the present disclosure are as follows: The expanded method of the present disclosure utilizes cold-welding technology using the same material at the connection between the new thermocouple and the old thermocouple, ensuring the accuracy of the thermocouple's measurement performance. High-temperature radiation-resistant insulating material is used to wrap the cold-welded portion to prevent contact between the two thermocouple wires, causing signal interference. The expanded method was used to repair both thermocouples in the C1 core thermocouple. After repair, the insulation resistance values ​​returned to normal. After one cycle of verification, the core thermocouple's functional indications were normal. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below with reference to specific embodiments.

[0018] According to one aspect of an embodiment of the present disclosure, a method for extending and replacing a core thermocouple connector is provided, the method comprising steps 100 to 106 .

[0019] Step 100: Select a new thermocouple made of the same material as the old thermocouple, select a new thermocouple connector of the same model as the old thermocouple connector, weld one end of the new thermocouple to the new thermocouple connector, and seal and protect.

[0020] In step 101, the other end of the new thermocouple is cut off to a predetermined length (e.g., the predetermined length may be between 30-40 cm), and then the other end of the new thermocouple is polished until the thermocouple wire is exposed. The positive and negative poles of the exposed wire are determined, so that the length of the positive wire is greater than the length of the negative wire.

[0021] Step 102 , cutting off the old thermocouple connector, grinding the old thermocouple at the cut portion until the old thermocouple filament is exposed, and determining the positive and negative poles of the filament so that the length of the positive filament is shorter than the length of the negative filament.

[0022] Step 103: Use a ferrule connector of the same model as the primary seal of the old thermocouple and insert the ferrule connector into the wire of the old thermocouple.

[0023] In step 104, the positive wire of the new thermocouple is brought into contact with the positive wire of the old thermocouple, and the negative wire of the new thermocouple is brought into contact with the negative wire of the old thermocouple. A high-temperature-resistant insulating sheet is used to isolate the positive and negative wires to prevent contact between the wires and measurement errors. An extension tube is selected to surround the new and old thermocouples. For example, nuclear-grade instrument tubing (such as 3 / 8 Swagelok instrument tubing) can be used as the extension tube. Nickel tubing is used to cold-weld the new and old thermocouples to the outside of the extension tube.

[0024] Step 105: After the cold welding is completed, a filler material is used to fill the extension tube with the new thermocouple and the old thermocouple to insulate and seal the new thermocouple from the outside world. The filler material can be, for example, epoxy resin or magnesium oxide powder. The new guide tube of the expansion method is filled with epoxy resin or magnesium oxide powder to ensure reliable insulation of the expanded portion of the thermocouple.

[0025] In step 106 , the newly extended thermocouple is fixed using a connector (the connector may be, for example, a Swagelok connector).

[0026] The technical solution disclosed in the present invention can, on the one hand, save the maintenance cost of the core thermocouples, and on the other hand, improve the maintenance efficiency, which can reduce the downtime of the unit, increase the availability of the unit, and thus improve the power generation output.

[0027] While various embodiments of the present disclosure have been described above, the above descriptions are illustrative, non-exhaustive, and not intended to be limiting of the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements to existing technologies, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for extending and replacing a core thermocouple connector, characterized in that: The method comprises: Step 100: selecting a new thermocouple made of the same material as the old thermocouple, selecting a new thermocouple connector of the same model as the old thermocouple connector, welding one end of the new thermocouple to the new thermocouple connector, and sealing and protecting them; Step 101: Cut off the other end of the new thermocouple by a preset length, then polish the other end of the new thermocouple until the thermocouple wire is exposed, and determine the positive and negative poles of the exposed wire, so that the length of the positive wire is greater than the length of the negative wire. Step 102: Cut off the old thermocouple connector and polish the old thermocouple at the cut portion until the old thermocouple filament is exposed. Then, determine the positive and negative poles of the filaments so that the length of the positive filament is shorter than the length of the negative filament. Step 103, using a ferrule connector of the same model as the primary seal of the old thermocouple, and inserting the ferrule connector into the wire of the old thermocouple; Step 104: contacting the positive wire of the new thermocouple with the positive wire of the old thermocouple, contacting the negative wire of the new thermocouple with the negative wire of the old thermocouple, isolating the positive wire and the negative wire with a high-temperature resistant insulating sheet, selecting an extension tube to surround the new thermocouple and the old thermocouple, and cold-pressing welding the new thermocouple and the old thermocouple using a nickel tube outside the extension tube; Step 105, after the cold pressure welding is completed, the new thermocouple and the old thermocouple are filled with a filling material in the extension tube so that the new thermocouple and the old thermocouple are insulated and sealed from the outside world; Step 106: Use a joint to fix the newly extended thermocouple.

2. The method according to claim 1, characterized in that The preset length is between 30-40 cm.

3. The method according to claim 1, characterized in that The extension tube is 3 / 8 Swagelok instrument line.

4. The method according to claim 1, wherein The filling material is epoxy resin or magnesium oxide powder.

5. The method according to claim 1, wherein The fittings described are Swagelok fittings.