JPS6011516Y2 - nuclear fuel rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to nuclear fuel rods fitted with spacer wires for use in fast breeder reactors.

As shown in Figure 1, a nuclear fuel rod consists of a hollow cladding tube 4 containing nuclear fuel material, a lower end plug 1 and an upper end plug 3 welded to both ends, and a spacer wire 2 wound around the outside. It will be done.

As shown in Figs. 2 and 3, the spacer wire is made by passing one end of the spacer wire 2 through a small hole provided in the lower end plug 1 and forming a ball (ball stopper) by a method such as welding. , the spacer wire 2 is wound around the nuclear fuel rod body while applying a constant tension, and the other end of the spacer wire 2 is welded and fixed to the upper end plug 3.

Conventionally, spacer wires have been soft-annealed to make the work easier.

However, it has recently been discovered that cold-worked wire has superior properties to annealed wire at the temperatures at which nuclear fuel rods are commonly used.

Now, if an annealing material is used for the spacer wire 2, no gap will be created between the nuclear fuel rod body and the spacer wire 2, as shown in FIG.

This is because the wire is soft, so it adapts to nuclear fuel rods.

However, when a cold-worked wire is used, the wire is hard and has spring properties, so there is a gap A between the end plug and the wire at the wire bending part of the lower end plug, as shown in Figure 4. arise.

This is not allowed by nuclear fuel rod manufacturing standards.

One possible way to eliminate this problem is to increase the tension applied to the spacer wire and reduce the curvature of the bent portion of the wire, but this is undesirable because it increases the stress on the spacer wire nuclear fuel rod.

Therefore, it is desirable to be able to wrap and attach a spacer wire that has been processed with cold oil around a nuclear fuel rod body without any gaps.

The present invention proposes a spacer wire that has been subjected to cold working and is wrapped around a nuclear fuel rod body without any gaps.

The present invention is obtained by winding a cold-worked spacer wire around a small-diameter round rod, shaping the wire, and wrapping the wire around a nuclear fuel rod body.

As shown in FIG. 5, a small hole is provided in a round rod 7 having an outer diameter smaller than that of the nuclear fuel rod body, and one end of a cold-worked spacer wire is inserted into the hole. Wrap it around the outside.

The spacer wire is then removed from the round bar.

However, when the spacer wire is removed from the round rod, the bending curvature increases due to the spring back of the wire, so the thickness of the round rod 7 is determined so that the wire will come into close contact with the nuclear fuel rod body in that state. There is a need to.

One end of the spacer wire removed from the round rod is fastened to the lower end plug of the nuclear fuel rod, and when tension is applied to the wire, the curvature of the bent portion of the wire matches the body of the nuclear fuel rod, as shown in Figure 6. As such, there is no gap between the spacer wire and the nuclear fuel rod body.

If the spacer wire is wound in this state, a good nuclear fuel rod with no gaps between the spacer wire and the nuclear fuel rod body can be provided.

As described above, according to the present invention, a nuclear fuel rod can be obtained that exhibits excellent effects such as being able to wrap even hard cold-worked spacer wires without gaps.

[Brief explanation of the drawing]

Figure 1 is an overall view of the nuclear fuel rod, Figures 2 to 4 are partial views showing the spacer and wire stopper, and Figures 5 and 6.
The figure is a partial view showing a spacer wire ball stopper according to the present invention. 4...Nuclear fuel rod body, 5...King stop,
6... Spacer wire subjected to cold working.

Claims (1)

[Scope of utility model registration request] In a device comprising a nuclear fuel rod body and a cold-worked spacer wire wound around the nuclear fuel rod body, a spacer wire having an outer diameter smaller than that of the nuclear fuel rod body to be wound around one end of the spacer wire. When the rod is inserted into a small hole provided in a round rod, wound around the outer periphery of the rod, bent, and then removed from the rod, the curvature of the bent portion and the curvature of the outer diameter of the nuclear fuel rod body are different. A nuclear fuel rod characterized by being provided with a bent portion formed to fit together.