JP2926626B2 - Separator assembly for transportation of fuel assemblies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention is applied to a case where a fuel assembly is mounted between fuel rods to prevent generation of fretting flaws due to vibration of the fuel rods. The present invention relates to a separator assembly for transport of a fuel assembly to be prevented.

(Prior Art) FIG. 7 shows a typical fuel assembly used in a boiling water reactor. This fuel assembly 1 includes a plurality of fuel rods 2 arranged in a grid and A spacer 3 for maintaining a constant horizontal spacing between the fuel rods 2;
The upper tie plate 4 and the lower tie plate 5 for supporting the tie plate, and a combined fuel rod 6 for connecting the two tie plates 4, 5 to each other. At present, in transporting the fuel assembly 1, a polyethylene transport separator is used to prevent fretting flaws caused by the vibration of the fuel rod 2.

FIG. 8 shows this type of conventional transport separator,
FIG. 9 and FIG. 10 show how the transport separator is mounted on the fuel assembly.

The conventional transport separator 7, as shown in FIG.
It is mounted between the fuel rods 2 arranged in a grid. As shown in FIGS. 8 and 10, the transport separator 7 is provided with an elastic flat plate portion 8 for obtaining a spring property, and is provided on both surfaces of the elastic flat plate portion 8 at predetermined intervals, and is directly attached to the fuel rod 2. And a plurality of projecting support portions 9 in contact with each other. Then, a reaction force is applied to the adjacent fuel rods 2 by the elastic force of the elastic flat plate portion 8, thereby preventing the fuel rods 2 from vibrating.

Other known transport separators include, for example, JP-A-60-111184 and JP-A-60-1995491.
JP, JP-A-62-145195 or JP-A-1-15
There is one described in JP-A-1299.

(Problems to be Solved by the Invention) Since the conventional transport separator 7 is formed of a synthetic resin, the material, thickness, shape and the like are limited in order to obtain an appropriate elastic force, and moreover, it is accurate. In order to obtain a proper shape, manufacturing methods such as casting into a mold are limited, and there is a problem that manufacturing costs increase.

Further, in general, there is a problem that the synthetic resin is weak to heat and melts at a certain temperature or higher, or its elasticity decreases due to softening, so that it cannot be used in a situation where the fuel rod temperature becomes high.

As a method of solving this, it is conceivable to manufacture with a heat-resistant resin. However, since the heat-resistant resin having a higher heat-resistant temperature is more expensive, the manufacturing cost is significantly increased and is not practical.

The present invention has been made in consideration of such points,
An object of the present invention is to provide a fuel assembly transport separator that does not change its elastic force over a wide temperature range and can be manufactured at low cost.

[Configuration of the invention]

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a fuel assembly comprising a plurality of fuel rods bundled in a lattice shape, which is mounted between the fuel rods, In the fuel assembly and the transport separator assembly, each of which has a plurality of protruding support portions provided at predetermined intervals on both surfaces of the elastic flat plate portion and directly contacting the fuel rods, the elastic metal sheet has irregularities. A core member formed by integrally processing an elastic flat plate portion and each protruding support portion, and a synthetic resin having flexibility disposed by spraying at least a portion of the surface of the core member that comes into contact with the fuel rods And a plurality of the core members are integrally connected by spot welding.

(Operation) In the fuel assembly transport separator according to the present invention, since the elastic force is obtained by the elastic thin metal core member, the change in the elastic force can be reduced over a wide temperature range. , Stable elastic force is secured. On the other hand, since a flexible synthetic resin surface member is disposed on the surface of the core member at least at a portion that comes into contact with the fuel rod, contact between metals is prevented.

(Embodiment) An embodiment of the present invention will be described below with reference to FIG. 1 and FIG.

FIG. 1 shows an example of a transport separator for a fuel assembly according to the present invention. The transport separator 11 includes an elastic flat plate portion 12 for obtaining spring properties and two surfaces of the elastic flat plate portion 12. And a plurality of projecting support portions 13 provided at predetermined intervals. This transport separator 11
In order to prevent fretting damage caused by vibration of the fuel rods, each protruding support portion 13 directly contacts the fuel rods when mounted between fuel rods (not shown) of the fuel assembly. Has become.

As shown in FIG. 2, the transport separator 11 is provided with a core member 14 formed by integrally forming an elastic flat plate portion 12 and each protruding support portion 13 by subjecting a metal sheet having elasticity to unevenness. On the entire surface of both sides of the core member 14, a surface member 15 made of a synthetic resin having flexibility is provided.

As the core member 14, stainless steel, aluminum, an aluminum alloy, iron, or the like is used, and as the surface member 15, polysulfone, polyamideimide, PEE
K, polyether sulfone, polyether imide, wholly aromatic polyimide, polyamino bismaleide, or epoxy-modified polyimide is used.

As described above, since the elastic flat plate portion 12 and each protruding support portion 13 are constituted by the core member 14 made of a thin metal plate having elasticity, it can be manufactured easily and with high precision by pressing or the like. The shape provides a sufficient reaction force to a wide range of compressive stress.

Further, on the surface of the core member 14, a surface member 15 made of synthetic resin or the like is provided.
Since the metal is coated, it is possible to prevent the core member 14 and the fuel rods from coming into contact with each other while keeping the hardness of the projecting support portion 13 appropriately, thereby preventing the occurrence of scratches.

Further, in an application to a fuel assembly in which significant decay heat is generated and a fuel rod temperature is relatively high, such as a plutonium-uranium mixed oxide fuel, as the core member 14,
By using a metal that has a small change in compressive force due to temperature and that can be used up to a higher temperature, and by applying a heat-resistant resin as the surface member 15, even at a high temperature, the performance as the transport separator 11 is sufficiently secured. be able to.

In the case of the transport separator 11 according to the present embodiment, even if a heat-resistant resin is used as the surface member 15, the required amount is extremely small, so that the manufacturing cost can be reduced.

Example The present inventors, as shown in FIG.
using a stainless steel thin plate (stainless steel foil) with a total height of 4.2 to 5.0 mm
Core member 14 with a spacing of 15 to 20 mm, a width of 50 mm and a length of 63 mm
Then, the surface member 15 was coated on the surface to produce the transport separator 11.

Then, using this transport separator 11, the total height is 4.0 m
When it was compressed to m, it was confirmed that a compression force of 1 to 8 kg was obtained.

The coating method of the surface member 15 includes a dipping method (dipping), a powder electrostatic coating method, a spraying method (spraying), and the like. When a coating film test was performed, as shown in FIG.
It was confirmed that a film having good adhesion to No. 4 was obtained.

FIGS. 5 and 6 show another embodiment of the present invention, in which a plurality of transport separators 11 mounted between fuel rods are integrally connected.

That is, as shown in FIG. 5, the plurality of transport separators 11 mounted between the fuel rods are aligned with the intervals between the fuel rods in a metal U-shaped frame 16 coated with a synthetic resin. It is arranged. Each of these transport separators 11 has a sixth
As shown in the figure, spot welding 18
By doing so, it is configured to be fixed to the U-shaped frame 16. The fixed portion is coated with a synthetic resin by a spray method or the like.

In this way, the plurality of transport separators 11 are
By integrating at 16, the work time for attaching and detaching the transport separator 11 can be greatly reduced, and the radiation exposure dose of the workers can also be reduced.

In each of the above embodiments, the case where the surface member 15 of the core member 14 is provided has been described.
The surface member 15 may be arranged only at a portion of the surface that comes into contact with the fuel rod.

〔The invention's effect〕

As described above, the present invention is configured such that the separator includes a core member made of a thin metal plate and a surface member made of a synthetic resin disposed at least in a portion of the surface of the core member that comes into contact with the fuel rod. Under a wide range of temperature and vibration conditions, a necessary elastic force can be obtained, and even in a high temperature region, a reasonable transport separator having appropriate hardness without damaging the fuel rod can be provided at a low cost. .

[Brief description of the drawings]

1 is a perspective view showing a fuel assembly transport separator according to one embodiment of the present invention, FIG. 2 is an enlarged sectional view of a part II in FIG. 1, and FIGS. 3 and 4 are the present inventors. FIG. 5 is a perspective view of a transport separator according to another embodiment of the present invention, and FIG. 6 is an enlarged view of a part VI in FIG. 7 is a partially cutaway side view showing an example of the fuel assembly, FIG. 8 is a perspective view showing a conventional fuel assembly transport separator, FIG. 9 and FIG.
The figure is an explanatory view showing a state in which the separator is mounted between the fuel rods. 1 ... fuel assembly, 2 ... fuel rod, 6 ... combined fuel rod,
11 ... Transportation separator, 12 ... Elastic flat plate, 13 ... Protrusion support, 14 ... Core member, 15 ... Surface member, 16 ... U-shaped frame.

Continued on the front page (72) Inventor Yuichi Kusumi 2585 Nishi-Hachiman, Ryuo-cho, Nakakoma-gun, Yamanashi Prefecture (72) Inventor Hisashi Okuda 4-13-1 Tokodai, Tokodai, Ishioka-shi, Ibaraki Pref. Toyo-ku 2-3-6-K506 (72) Inventor Shinichi Mochizuki 3-14-17 Funabashi, Setagaya-ku, Tokyo (56) References JP-A-4-54490 (JP, A) (58) Fields investigated ( Int.Cl. ⁶ , DB name) G21C 3/00

Claims (1)

(57) [Claims] 1. A fuel assembly comprising a plurality of fuel rods bundled in a lattice and mounted between said fuel rods, said elastic rods being provided at predetermined intervals on both sides of said elastic plate. In a fuel assembly transport separator assembly composed of a plurality of projecting support portions that directly contact the surface, an elastic metal plate is subjected to unevenness processing to form an elastic flat plate portion and each projection support portion. And a surface member made of synthetic resin having flexibility, which is disposed by spraying on at least a portion of the surface of the core member that comes into contact with the fuel rod, and spots the plurality of core members. A separator assembly for transporting a fuel assembly, wherein the separator assembly is integrally formed by welding.