JPH0427892A - Manufacture of spacer plate for nuclear fuel - Google Patents

Abstract

PURPOSE:To manufacture a highly accurate spacer plate without any disorder in dimensional accuracy by finishing the spacer plate with afterward finishing process even if some dimensional changes of element material for processing appear being caused by heating process after the primary processing. CONSTITUTION:To a plate 5 of an element material consisting of an alloy of nickel radical, shearing process of windows 3 and fixed protrusion parts 2a, and bending process of fixed protrusion parts 2 and elastic protrusions 1, both of which require comparatively less graded accuracy as a primary machinery processing, are carried out. Then, the plate 5 of the element material, after being subject to the aforementioned process, is heat-processed as shown in the figure (b) and, after that, is subject to shearing process 6 for an outer shape shaping and shearing process of fitting slits 4 which require highly graded accuracy as a finishing process. The spacer plate obtained in such way is a highly accurately finished goods even if the plate of the element material deforms by the heating process, since the sharing process for the outer shape shaping and of the fitting slits which require highly graded accuracy are carried out as a final processing stage.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a spacer used in a nuclear fuel assembly, particularly a spacer plate constituting a lattice-type spacer.

(Prior art) In a nuclear reactor fuel assembly, as shown in Fig. 4,
Nuclear fuel spacers are installed in multiple stages in the axial direction to accurately maintain the spacing between the large number of fuel rods (7) and simple control rod guides (8) arranged in parallel to each other, and to restrain lateral vibrations. (9) is provided, and the spacer (9)
is an important part that maintains the fuel rods etc. at regular intervals for several years in a nuclear reactor where high temperature, high pressure water flows at high speed.Many thin spacer plates are carved into the spacer plate. The fitting slits are used to combine them in a lattice shape as shown in FIG. 5, and the outer periphery is surrounded by side plates αυ.

By the way, in such a spacer, the spacer plate constituting it has a window (3) as shown in FIG.
and a slit (4) for fitting.
As shown in figure (b), elastic protrusions (1) for holding fuel rods
and a fixing protrusion (2). As mentioned above, the spacer is important in holding the fuel rods, and the performance of the spacer is greatly influenced by the accuracy of the position and shape of the slits and projections.
Particularly high precision is required for the spacer plates. Therefore, the conventional manufacturing method for such a spacer plate is to process a thin plate by press working or the like, and after the shape is determined by the process, it is heat-treated to produce a product. (Problem to be Solved by the Invention) However, in the above method, deformation such as distortion due to stress release and dimensional change due to shrinkage occurs in the spacer plate due to heat treatment, so it is difficult to manufacture a spacer plate with high precision to meet the requirements. That was difficult.

In addition, taking into account deformation due to heat treatment in some areas,
Attempts have been made to manufacture spacer plates by setting the shape of the spacer plates in advance, but even with this method, deformation due to heat treatment is not uniform, so it is still insufficient to improve processing accuracy.

Furthermore, it has been proposed to heat-treat the thin plate and then perform press working, but this method suffers from problems such as distortion remaining in the processed portion and difficulty in performing highly processed processes.

The present invention deals with the actual situation such as on ridges, and improves the machining accuracy of the spacer plate by dividing the machining into primary and finishing parts and inserting a heat treatment process between them, resulting in high precision that is not affected by dimensional changes due to heat treatment The purpose is to manufacture a spacer plate of.

(Means for Solving the Problems) Accordingly, the method for manufacturing the spacer plate for nuclear fuel of the present invention, which meets the above purpose, involves subjecting a thin plate material to mechanical processing such as bending and shearing, and heat treatment. When manufacturing, the machining is divided into primary processing and finishing processing,
It is characterized in that first, primary processing is performed, then heat treatment is performed, and after the deformation due to the heat treatment is completed, finishing processing is performed.

In this case, specifically, primary bending and shearing, which do not require relatively high precision, are performed as primary processing, and shearing, which requires high precision, and finishing bending, which also requires high precision, are performed as finishing processing. Further, as the material for the spacer plate, a nickel-based alloy plate is suitable from the standpoint of effectively obtaining a high-precision spacer plate by these manufacturing methods.

This is because, in the case of nickel-based alloys, dimensional changes such as shrinkage occur due to aging heat treatment.

Further, even in the case of zirconium-based alloys, residual stress is released by stress relief heat treatment and distortion occurs, so the usefulness of the present invention is extremely high.

(Function) According to the manufacturing method of the present invention as described above, even if dimensional changes occur in the processed material due to heat treatment after the primary processing, the finishing is performed by the subsequent finishing processing, so the dimensional accuracy etc. It becomes possible to create a highly accurate spacer plate without any deviations.

In addition, in the above manufacturing method, when a nickel-based alloy is used as the material for the spacer plate, the alloy undergoes heat treatment.
Since the hardness is suitable for shearing and bending processes that require precision, it is possible to obtain a spacer plate with higher precision through finishing processing.

(Example) Hereinafter, a method for manufacturing a spacer plate of the present invention will be described with further reference to the accompanying drawings.

FIG. 1(a) is a partial front view showing an example of a spacer plate manufactured by the manufacturing method of the present invention, and FIG. 1(b) is a sectional view taken along line A-A in FIG. 00) is a spacer plate, (1) is an elastic protrusion for holding fuel rods on the spacer plate α0), (2) is a fixed protrusion for holding fuel rods, (3) is a window,
(4) shows fitting slits when spacer plates are assembled in a lattice shape. FIG. 2 shows one mode of manufacturing a spacer plate having the above shape, and will be explained below with reference to FIGS. 2(a) to (c). In FIG. 2(a), ( 5) shows a thin plate material made of nickel-based metal, and the material plate (5) is used for the upper and lower parts (2a) of the window (3) and the fixing projection (2), which do not require relatively high precision as primary machining. Shearing processing and bending processing of the fixed protrusion (2) and the elastic protrusion (1) are performed.

After the above processing, the same material plate (5) is shown in the same figure (CI).
After undergoing the aging treatment as shown in FIG. 3C, as shown in FIG.

The spacer plate obtained in this manner becomes a highly accurate finished product because even if the material plate is deformed by heat treatment, the external shape and fitting slit, which require high precision, are sheared last. Moreover, since the material plate is made of a nickel-based alloy as described above, and the nickel-based alloy plate is hardened to a hardness suitable for shearing after heat treatment, the spacer plate obtained by this manufacturing method has a clean finish of shearing. It becomes more accurate.

Next, a second manufacturing method according to the present invention will be explained with reference to FIGS. 3(a) to 3(c).

In this manufacturing method, as shown in FIG. 3 (a), the primary machining process includes primary bending and shearing (not shown) of the upper and lower parts of windows and fixing protrusions that do not require relatively high precision.
After performing heat treatment as shown in the same figure (II),
As finishing processing, finishing bending processing and shearing of the outer shape of the spacer plate, fitting slits, etc. are performed. Compared to the method of the previous embodiment, the manufacturing method of this embodiment is characterized in that the primary bending process is performed in the primary process, and the final bending process is performed in the finishing process,
This method is effective when it is difficult to perform bending with a large degree of processing after heat treatment, and by performing a certain amount of bending before heat treatment, it has the advantage of allowing finish bending to be performed with high precision and without difficulty.

Note that this manufacturing method also has the following advantage: 1. Since the nickel-based alloy used as the material is hardened to a hardness suitable for bending after heat treatment, the finish bending can be performed with high precision.

(Effects of the Invention) As explained above, in the method for manufacturing a spacer plate for nuclear fuel of the present invention, machining is performed in two stages in manufacturing the spacer plate, first performing primary processing, then heat treatment, and then Finishing processing is performed after the heat treatment, and even if the material undergoes dimensional changes due to heat treatment, finishing processing is performed after this, so it is possible to achieve high precision with no deviations in dimensional accuracy, which was previously impossible. This method has the remarkable effect that the spacer plate can be manufactured and that the finishing process can be performed relatively easily since the spacer plate has been previously subjected to secondary processing.

Moreover, by using a nickel-based alloy as the material for the spacer plate, the hardening of the nickel-based alloy after heat treatment can be used to perform the finishing bending and shearing processes neatly, making it possible to obtain a spacer plate with higher precision. This is expected to have practical effects.

[Brief explanation of drawings]

FIG. 1(A) is a partial front view of a spacer plate manufactured by the manufacturing method of the present invention, FIG. 1(0) is a sectional view taken along line A-A in FIG. 1(A), and FIG. The same figure (b) shows the heat treatment process of the same example manufacturing method, the same figure (c) shows the finishing machining of the same example manufacturing method, and the third figure shows the primary machining of the example manufacturing method. Figure (a) shows the primary bending process of the manufacturing method of the embodiment of the tube 2 of the present invention, figure (I) shows the heat treatment process of the manufacturing method of the example, and figure (h) shows the finishing process of the manufacturing method of the example. FIG. 4 is a front view showing the fuel assembly, and FIG. 5 is a perspective view showing the spacer. (1)...Elastic protrusion for holding fuel rods, (2)...Fixing protrusion for holding fuel rods, (3)...Window, (4)...Slit for fitting, (5
)...Material board, 00)...Spacer board. Patent Applicant Nuclear Fuel Industry Co., Ltd. Agent Patent Attorney Yasushi Miyamoto Figure (a) (b) Figure (a) (b) (c) Figure

Claims (1)

[Claims] 1. When manufacturing a spacer plate using a thin plate as a material through mechanical processing such as bending and shearing, and heat treatment, the machining is divided into primary processing and finishing processing, and the material is first processed. 1. A method of manufacturing a spacer plate for nuclear fuel, which comprises performing primary processing, then heat treatment, and after completion of the deformation caused by the heat treatment, finishing processing is performed. 2. The method of manufacturing a spacer plate for nuclear fuel according to claim 1, wherein the primary processing is bending or shearing processing that does not require relatively high precision, and the finishing processing is shearing processing that requires high precision. 3. According to claim 1, the primary processing is a primary bending process or a shearing process that does not require relatively high precision, and the finishing process is a finish bending process that requires a high precision or a shearing process that also requires a high precision. A method for manufacturing a spacer plate for nuclear fuel. 4. The method for manufacturing a spacer plate for nuclear fuel according to claim 1, 2 or 3, wherein the thin plate material is a nickel-based alloy material.