CN111477362A - An annular fuel rod fixing snap ring and fixing device - Google Patents

Abstract

A fixing clamp ring and a fixing device for an annular fuel rod comprise a fixing nut and a clamp ring; the clamping ring is integrally of a C-shaped structure, and a mounting circular hole is formed in the opening; the lower end of the fuel rod is provided with a groove; the lower end of the fuel rod is arranged on the lower tube seat through a fixing nut. When the disassembly is needed, force to two sides is applied from the opening of the clamping ring, so that the quick disassembly is realized. The inner side of the fixed nut is provided with a thread structure. The screw thread of the inner side of the fixed nut is matched with the screw thread of the lower tube seat. And a snap ring is arranged on the lower side of the fixed nut.

Description

An annular fuel rod fixing snap ring and fixing device

technical field

The invention belongs to the technical field of nuclear fuel, and in particular relates to an annular fuel rod fixing snap ring and a fixing device.

Background technique

In the current design of the fuel assembly, the fuel rod is clamped by the spacer frame and fixed between the upper and lower tube seats, and there is a certain gap between the lower end plug of the fuel rod and the lower tube seat. With the slackening of the spacer during the operation of the reactor, the clamping force is weakened, which is not enough to fix the fuel rods, and the fuel rods fall. integrity, increasing the probability of fuel rod failure. In addition, when the spacer grid loses its clamping force, the fuel rods falling on the lower tube seat may move up and down under the action of the lifting force of the water flow, which increases the friction between the fuel rod and the spacer grid, as well as with the lower tube seat. The probability of collision between them is not conducive to the safety of fuel rods.

The fuel rods with free lower end plugs are prone to flow-induced vibration during the coolant flushing process, and fretting abrasion occurs at the contact position between the vibrating fuel rods and the spacer grid, resulting in thinning or even rupture of the fuel rod cladding thickness, which may cause radioactive material leakage.

The annular fuel rods cool the fuel rods through closed inner and outer coolant passages. With the operation of the reactor, tiny impurities are easy to appear in the main system, for example, the wastes remaining in the manufacturing process of the internal components of the pressure vessel or in the main circuit pipeline, or the corrosion products formed during the operation of the reactor, etc., can easily cause fuel The flow channel of the rod is blocked, and the center hole of the lower end plug is the only water inlet hole in the internal flow channel. If the water inlet hole of the lower end plug is blocked, the flow rate of the inner flow channel of the annular fuel rod will be reduced, and the sufficient cooling capacity of the fuel rod cannot be maintained, threatening the Fuel rods are safe.

SUMMARY OF THE INVENTION

The purpose of the present invention is to design an annular fuel rod fixing device aiming at the above-mentioned defects of the prior art.

The technical scheme of the invention is as follows: an annular fuel rod fixing snap ring and a fixing device, comprising a fixing nut, a snap ring and a fuel rod; the lower end of the fuel rod is provided with a groove;

When disassembly is required, force is applied to both sides from the opening of the snap ring, so that rapid disassembly can be achieved.

The lower end of the fuel rod is mounted on the lower tube seat through a fixing nut.

There is a threaded structure on the inside of the fixing nut.

The threads on the inside of the retaining nut match the threads on the lower socket.

Install a snap ring on the underside of the retaining nut.

The snap ring has a C-shaped structure as a whole.

There is a mounting hole at the opening of the snap ring.

The annular fuel rod fixing snap ring and the fixing device are used in pressurized water reactors, marine power reactors, fast reactors and boiling water reactors.

The annular fuel rod fixing snap ring and the fixing device are applied to power reactors and heavy water reactors.

The beneficial effects of the present invention are:

The lower end fixing piece connects and fixes the lower end plug with the lower tube seat, so as to prevent the fuel rods from falling on the lower tube seat during the operation of the reactor, without falling impact force, and reducing the failure probability of the fuel rods. At the same time, the lower end fixing piece fixes the fuel rod on the lower tube seat, which ensures that the fuel rod does not move axially under the action of the lifting force of the coolant flow, and reduces the friction between the fuel rod and the spacer.

The lower end plug is fixed to the lower tube seat by the lower end fixing member, which reduces the flow-induced vibration caused by the flushing of the fuel rod by the coolant, thereby reducing the fretting abrasion of the fuel rod and reducing the risk of failure of the fuel rod.

Description of drawings

Fig. 1 is a schematic diagram of the annular fuel rod fixing snap ring and the fixing device fuel rod according to the present invention

2 is a schematic diagram of the installation of the annular fuel rod fixing snap ring and the fixing device according to the present invention

Figure 3 Schematic diagram of the installation of the annular fuel rod fixing snap ring and the fixing device according to the invention

4 is a schematic diagram of the annular fuel rod fixing snap ring and fixing device fixing nut according to the present invention

Figure 5 Schematic diagram of the annular fuel rod fixing snap ring and the fixing device snap ring according to the invention

In the figure: fixing nut 1, snap ring 2, groove 3, lower tube seat 4, fuel rod 5, mounting hole 6

Detailed ways

An annular fuel rod fixing snap ring and a fixing device, including a fixing nut 1 and a snap ring 2, the fixing nut 1 is shown in Figure 4, and its inner side has a threaded structure; and the structure of the snap ring 2 is shown in Figure 5, and its whole is as follows C-shaped structure, there is a mounting hole 6 at the opening, which plays a role of mounting and fixing; the fuel rod 5 is shown in Figure 1, and the lower end of the fuel rod 5 has a groove 3.

As shown in Figures 2 and 3 , the lower end of the fuel rod 5 is installed on the lower socket 4 through the fixing nut 1 , the inner thread of the fixing nut 1 is matched with the thread of the lower socket 4 , and then a snap ring is installed on the lower side of the fixing nut 1 2, thereby preventing the loosening of the fixing nut 1.

The device has the characteristics of anti-vibration and will not fall off in the case of vibration;

When disassembly is required, force to both sides is applied from the opening of the snap ring 2, so as to realize rapid disassembly.

Claims (10)

1. The utility model provides a snap ring and fixing device are fixed to annular fuel rod which characterized in that: comprises a fixed nut (1), a snap ring (2) and a fuel rod (5); the lower end of the fuel rod (5) is provided with a groove (3); the lower end of the fuel rod (5) is arranged on the lower tube seat (4).

2. The annular fuel rod fixing snap ring and fixing device as claimed in claim 1, wherein: when the disassembly is needed, force towards two sides is applied from the opening of the clamping ring (2), so that the quick disassembly is realized.

3. The annular fuel rod fixing snap ring and fixing device as claimed in claim 1, wherein: the lower end of the fuel rod (5) is arranged on the lower tube seat (4) through a fixing nut (1).

4. The annular fuel rod fixing snap ring and fixing device as claimed in claim 3, wherein: the inner side of the fixed nut (1) is provided with a thread structure.

5. The annular fuel rod fixing snap ring and fixing device as claimed in claim 4, wherein: the thread on the inner side of the fixed nut (1) is matched with the thread of the lower tube seat (4).

6. The annular fuel rod fixing snap ring and fixing device as claimed in claim 1, wherein: a snap ring (2) is arranged on the lower side of the fixed nut (1).

7. The annular fuel rod fixing snap ring and fixing device as claimed in claim 6, wherein: the clamping ring (2) is of a C-shaped structure as a whole.

8. The annular fuel rod fixing snap ring and fixing device as claimed in claim 7, wherein: an opening of the snap ring (2) is provided with a mounting round hole (6).

9. The annular fuel rod fixing snap ring and fixing device as claimed in any one of claims 1 to 8, wherein: the annular fuel rod fixing clamp ring and the fixing device are applied to pressurized water reactors, marine power reactors, fast reactors and boiling water reactors.

10. The annular fuel rod fixing snap ring and fixing device as claimed in any one of claims 1 to 8, wherein: the annular fuel rod fixing clamp ring and the fixing device are applied to power piles and heavy water piles.

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