JP3428204B2 - Fuel assembly transport separator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel assembly transportation separator used for transportation or handling of a nuclear reactor fuel assembly.

[0002]

2. Description of the Related Art When transporting a fuel assembly from, for example, a processing plant to a nuclear power plant, in order to prevent damage to the fuel rods due to vibration during transportation and handling, FIG.
The fuel assembly transporting separator 1 shown in FIG. 15 is mounted as shown in FIG.

FIG. 13 is a perspective view showing a conventional fuel transport separator 1 with the fuel rod side up and the outer side down.
FIG. 14 is a perspective view showing that FIG. 13 is turned upside down so that the outside is up and the fuel rod side is down.

As is apparent from FIGS. 13 and 14, a conventional fuel transportation separator 1 has a U-shaped outer frame 2 and this outer frame 2.
The inner surface, that is, in FIG. 13, a plurality of comb plates 3 which are vertically arranged in parallel at substantially equal intervals on the bottom surface. As shown in FIGS. 15 (a) and 15 (b), the comb plate 3 is a flat plate having elongated convex portions 4 formed in a crispy pattern on both surfaces.
15 (a) is a perspective view of the comb plate 3, and FIG. 15 (b) is a top view of FIG. 15 (a).

The U-shaped outer frame 2 and the plurality of comb plates 3 are made of plastic and integrally molded, and as shown in FIG. 16, a comb is formed between the plurality of fuel collecting rods 6 of the fuel assembly 5. The plate 3 is inserted and the fuel rod 6 is sandwiched between the protrusions 4.

FIG. 16 shows two fuel assembly transport separators 1 so as to cover one side of the fuel assembly 5 and about half of two adjacent sides so as to hold the outside of the fuel assembly 5 from the left and right. It shows a state in which four sides of the fuel assembly 5 are used and the separators 1 are attached to alternate sides along the longitudinal direction. In FIG. 16, reference numeral 7 is a spacer that holds the fuel rods 6 at a predetermined distance, and 8 is a lower tie plate that holds the lower ends of the fuel rods 6.

Further, in order to prevent the separator 1 from moving during transportation, the comb plate 3 is formed with a plurality of vertical elongated projections 4 as shown in FIG. The convex portion 4 of the plate 3 contacts. Fuel rods 6 (eight sides) are inserted between the outer frame 2 and the comb plate 3 and between the comb plate 3 and the comb plate 3. The separator 1 covers almost the entire length of the fuel rod at regular intervals during transportation as shown in FIG.

[0008]

By the way, the conventional fuel assembly transport separator 1 is used for transporting new fuel for a nuclear reactor. The new fuel refers to a freshly manufactured fuel assembly before being loaded into the core, and uses low enriched uranium dioxide.

Since the new fuel does not normally generate heat, the plastic transport separator 1 is used to maintain the soundness of the fuel assembly 5 from an accident such as vibration, drop or impact during transportation. .

Recently, a fuel assembly using a reprocessed pull thermal MOX fuel has been researched and developed, and when the fuel assembly is transported, heat may be generated in the fuel transportation container. Therefore, when the conventional plastic separator 1 is used, it becomes difficult to maintain the soundness of the fuel.

That is, simply speaking, the MOX fuel is a fuel in which uranium and plutonium are mixed, and the plutonium always generates heat when emitting α rays, so that the MOX fuel generates heat. Since the maximum temperature due to this heat is considered to be about 150 ° C. of the fuel rod, there is a problem that the conventional plastic separator 1 softens or melts the plastic so that it cannot be used.

In addition, assuming a vertical drop accident of the fuel assembly 5, it is possible that the boss surface of the lower tie plate 8 falls due to the impact load of the fuel rod 6. Along with this fall, bending occurs at the lower part of the fuel rod 6, and the lower tie plate 8
Between the spacer 7 and the spacer 7, the support span of the fuel rod 6 constrained by the separator 1 becomes short, and the deformation curvature of the fuel rod 6 becomes small, which causes the fuel rod 6 to be damaged.

17 (a) and 17 (b) show the appearance of the fuel rod 6 when it is deformed. 17A shows the case where the supporting span 1 of the fuel rod fixing portion 9 by the lower tie plate 8 and the supporting portion 10 by the spacer 7 is short, and FIG. 17B shows the case where the unsupported span L is long.

The deformation curvature r of the fuel rod 6 when the support span 1 in FIG. 17 (a) is short is smaller than the deformation curvature R when the support span L is long in FIG. 17 (b). Further, when the number of the mounted separators 1 increases, it becomes difficult for the heat from the fuel rods 6 to escape, and the mounting work also increases.

The present invention has been made to solve the above problems, and prevents damage to fuel rods due to heat and vibration during transportation or handling of a fuel assembly using MOX fuel, for example, to prevent fuel damage. Another object of the present invention is to provide a separator for transporting a fuel assembly which can maintain the soundness of the fuel.

[0016]

In order to achieve the above-mentioned object, the invention of claim 1 is one side and adjacent sides of a fuel assembly.
An almost U-shaped outer frame that covers about half of the two sides that can be worn, and this outer frame
Mounted between the fuel rods of each of the fuel assemblies attached to
And a comb plate to be inserted, wherein the outer frame and the comb plate are made of metal.
By attaching a corrugated metal plate inside the outer frame
And wherein such Rukoto. The invention of claim 2 is
Fold the corrugated metal plate into the corrugated metal plate mounting part formed on the outer frame.
The feature is that they are attached in an assembled manner.

[0017]

[0018]

[0019]

[0020]

According to the first and second aspects, the separator is made of metal.
The Rukoto forming, even when heat is generated in the fuel assembly, softened or, without or melt, because the fuel can be supported, Ru can ensure sound fuel.

[0021]

[0022]

Further, according to the first and second aspects, by attaching the corrugated metal plate to the outer frame, the corrugated metal plate functions as a leaf spring to mitigate vibration during transportation and prevent deformation and damage of the fuel rod. it can.

Further, according to the second aspect of the present invention , the corrugated metal plate is bent and attached to the corrugated metal plate mounting portion provided on the outer frame, so that the effect of the leaf spring of the corrugated metal plate is not suppressed, so that the fuel rod is deformed and damaged. Can be prevented.

[0025]

EXAMPLE An example of the fuel assembly transport separator according to the present invention will be described with reference to FIGS. 1 to 7. Figure 1
2 shows a perspective view in which the side for inserting the fuel assembly transporting separator of the present embodiment into the fuel body is directed upward and the outside is directed downward. FIG. 2 shows the state of FIG. With the upper surface of the above, the side to be inserted into the fuel rod faces downward and the outside faces upward.

That is, in FIG. 1 and FIG.
Reference numeral 11 denotes a fuel assembly transport separator according to the present embodiment. The separator 11 has a U-shaped outer frame that covers one side of the fuel assembly 5 and about half of two adjacent sides as shown in FIG. 12, a curved corrugated comb plate 13 mounted in the outer frame 12 and inserted between the fuel rods 6 and 6, and a corrugated metal plate 14.

Here, for convenience of description, in FIGS. 1 and 2, the outer frame 12 has its upper and lower portions referred to as bottom surfaces and both side portions referred to as side surfaces. That is, the outer frame 12 indicates a state in which both sides of the bottom surface are bent at right angles to form both side surfaces. The outer frame may be integrally formed by bending the bottom surface and the side surface by pressing or the like, or may be connected and integrated by folding, inserting, welding or the like of a steel plate.

The outer frame 12 is provided with a large number of circular heat dissipation holes 15 on both the bottom surface and the side surfaces, and the curved projections 16 are formed at the ends where the bottom surface is bent at a right angle to form both side surfaces. A notch 17 is provided in the part.

The comb plate 13 is a comb plate 13 composed of two corrugated plates arranged in series from both left and right sides along a line passing through the notches 17 and 17 provided on both side surfaces shown in FIG.
A plurality of (seven in the figure) comb plates 13 are arranged in parallel in the outer frame 12.

That is, the comb plate 13 is not a single continuous corrugated plate, but is composed of two corrugated plates obtained by dividing one corrugated plate from the center. Then, they are brought into contact with each other in the central portion with a little space, and they can be easily bent from the central portion. Also, multiple sheets (7 sheets in the figure)
In the comb plate 13, the three comb plates 13 in the central portion are shown in FIG.
As shown in (a), the length is shortened by the other comb plates 13 on both sides so as not to interfere with the water rod of the fuel assembly.

That is, the reason why the central portion is made shorter than both side portions is that the water rod of the fuel assembly is larger than the outer diameter of the fuel rod 6, so that the comb plate 13 has a uniform length. This is because the water rod deteriorates the adhesion and the insertion of the comb plate 13 is halfway.

The outer plate 12 and the comb plate 13 are joined by welding, but the outer frame 12 and the corrugated metal plate 14 are formed with a corrugated metal plate mounting portion 18 having a space by bending the ends of the outer frame 12. The corrugated metal plate 14 is mounted on the corrugated metal plate mounting portion 18.

The corrugated metal plate 14 has an outer frame 12 as shown in FIG.
The corrugated metal plate 14 is attached to the outer frame 12 with flexibility by bending the end part of the corrugated metal plate and sandwiching the curved surface part formed by bending the end part of the corrugated metal plate.

FIG. 5 is a partially enlarged view of the mounting portion of the outer frame 12 and the corrugated metal plate 14. As shown in FIG. 6A, the corrugated metal plate 14 is provided with an elliptic comb plate insertion hole 19 so as to be attached to the outer frame 12 through the space between the comb plates 13.

Since the corrugated metal plate 14 is also a portion that comes into contact with the fuel rods 6, the corrugated metal plate 14 is formed into a corrugated shape so that the contact portion has a curved surface. There is a mounting method.

FIG. 6A is a plan view of the corrugated metal plate 14 when viewed from the direction of FIG. 3A or the opposite direction, so that the comb plate 13 passes through the oval comb plate insertion hole 19. The corrugated metal plate 14 is located at the base of the comb plate mounting portion. The upper and lower ends shown by hatching in FIG. 6B are the parts attached to the outer frame 12.

FIG. 7 shows only the outer frame 12 of FIG. 4 (a), and the convex portion 16 and the corrugated metal plate mounting portion 18 are obtained by bending the outer frame 12 itself into a curved surface. The 16 and the attachment portion 18 are not attached to the outer frame 12.

FIG. 8 shows a deformation state of the outer frame 12 that is expected at the time of an accident. FIG. 8 (a) shows that the mounting surface of the comb plate 13 is curved, and FIG. 8 (b) shows the comb plate 13. 3 shows a deformed state in which the mounting surface is bent diagonally. When the comb plate mounting surface is deformed as described above, the comb plate mounting portion may be destroyed and the comb plate 13 may be removed from the outer frame 12. Therefore, the convex portion 16 is provided to prevent these deformations.

FIG. 9 partially shows a state in which the comb plate 13 is normally inserted between the fuel rods 6 and 6. FIG. 10 shows that the fuel assembly transport separator 11 of the present invention is attached to the fuel assembly. 4 shows a deformed state of the outer frame 12 and the comb plate 13 when the fuel rod 6 is deformed in the case. FIG. 11 shows an example in which the comb plate 13 is formed in a corrugated curved surface, and FIG. 12 shows an example in which the corrugated shape of the comb plate is formed by a square comb plate 20 formed in a rectangular shape at right angles.

The reason why the separator 11 of this embodiment is made of metal, particularly stainless steel is as follows. That is, since heat is generated from the MOX fuel, dew condensation may occur in the transportation container when the MOX fuel is stored in the transportation container. In addition, stainless steel is used because a light material is good and the material cost is relatively low so as not to increase the weight during transportation. Carbon steel cannot be used because it easily rusts even with metal.

As described above, according to the present embodiment, the fuel assembly transport separator 11 is arranged so that the comb plate 13 of the fuel assembly transport separator 11 is inserted between the fuel rods 6 as shown in FIG. Put on. FIG. 9 is an enlarged view of a portion where the comb plate 13 of the fuel assembly transporting separator 11 is inserted between the fuel rods 6 of the fuel assembly.

As is apparent from FIG. 9, in this embodiment, the comb plate 13 keeps the comb plate 13 in constant contact with the fuel rod 6 due to the curved waveform. Further, as shown in FIGS. 1 to 3, the notch 17 of the outer frame 12 prevents the outer frame 12 and the comb plate 13 from restraining the deformation of the fuel rod 6 when the fuel rod is deformed. Further, the convex portion 16 of the outer frame 12 prevents the comb plate 13 from coming off the outer frame 12 by deforming the comb plate 13 when the outer frame 12 is deformed.

FIG. 10 shows how the outer frame 12 and the comb plate 13 are deformed corresponding to the deformation of the fuel rod 6 when the fuel rod 6 is deformed. That is, as is apparent from FIG. 10, the cutout 17 is provided in the outer frame 12 and the comb plate 13 is divided into two plates, so that the deformation of the fuel rod 6 is difficult to be prevented.

Further, in the conventional plastic separator, the fuel rod 6 is not scratched even if there is a corner at the portion contacting the fuel rod 6, but it is made of metal as shown in FIGS. 12 (a) and 12 (b). Since the corners 21 of the square comb plate 20 are made of metal and are hard, the fuel rod 6
The fuel rod 6 is likely to be damaged in the portion in contact with
If it is severely damaged, it cannot be used as a fuel rod.

Therefore, as shown in FIGS. 11 (a) and 11 (b), the comb plate 13 is formed in a curved waveform so that it comes into contact with the fuel rod 6 on a curved surface so that the fuel rod 6 is vibrated during transportation to cause vibration. I try not to get scratches.

[0046]

According to the first and second aspects of the present invention, since the separator is made of metal, it is relatively lightweight, does not cause rust, and can soften or melt even if heat is generated in the fuel rod. no, Ru can ensure the soundness of the fuel assembly. Well
Was, Ru can be secured to mitigate vibration during fuel assembly transportation of the fuel rod integrity by corrugated metal plate attached to the outer frame, according to the invention of claim 1 and 2. Further, according to the invention of claim 2 , the vibration effect of the corrugated metal plate is not suppressed by folding the corrugated metal plate with the mounting portion of the corrugated metal plate provided on the outer frame.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a fuel assembly transport separator according to the present invention.

FIG. 2 is a perspective view showing FIG.

3A is a top view of FIGS. 1 and 2 viewed from the direction of arrow a, and FIG. 3B is a side view of the same viewed from the direction of arrow b.

FIG. 4A is a side view of FIGS. 1 and 2 seen from the direction of arrow c, and FIG. 4B is a sectional view taken along line XX of FIG.

5 is an enlarged vertical sectional view showing a state where a corrugated metal plate is attached to the outer frame in FIGS. 1 and 2. FIG.

6A is a plan view of the corrugated metal plate in FIGS. 1 and 2, and FIG. 6B is a sectional view taken along line YY of FIG.

FIG. 7 is a front view showing the relationship between the outer frame and the corrugated metal plate mounting portion in FIGS. 1 and 2.

FIG. 8A is a perspective view showing a curved surface deformation state of a comb plate attachment surface expected in an accident, and FIG. 8B is a perspective view showing a deformation state of the comb plate attachment surface bent at a diagonal line.

FIG. 9 is a vertical sectional view showing a comb plate inserted between fuel rods.

FIG. 10 is a partial cross-sectional view showing a deformed state of the outer frame and the comb plate when the fuel rod is deformed.

11 (a) is a perspective view of the comb plate in FIG.
(B) is a top view of (a).

FIG. 12 is a perspective view showing an example in which the comb plate of FIGS. 1 and 2 is formed into a square comb plate having an uneven surface shape, and (b) is a top view of (a).

FIG. 13 is a perspective view showing a conventional fuel assembly transport separator.

FIG. 14 is a perspective view showing FIG. 13 by turning over.

15A is a perspective view showing a comb plate in FIGS. 13 and 14, and FIG. 15B is a top view of FIG.

FIG. 16 is a perspective view showing a state where the conventional fuel assembly transport separator shown in FIGS. 13 and 14 is mounted on a fuel assembly.

17 (a) is an external view showing a state in which the fuel rod is largely deformed, and FIG. 17 (b) is an external view showing a state in which the fuel rod is slightly deformed compared to (a).

[Explanation of symbols]

1 ... Conventional fuel assembly transport separator, 2 ... Outer frame, 3
... comb plate, 4 ... convex part, 5 ... fuel assembly, 6 ... fuel rod, 7
... Spacer, 8 ... Lower tie plate, 9 ... Fuel rod fixing part, 10 ... Fuel rod supporting part, 11 ... Fuel assembly transport separator of the present invention, 12 ... Outer frame, 13 ... Comb plate, 14 ... Corrugated metal plate ,
15 ... Heat dissipation hole, 16 ... Convex part, 17 ... Notch, 18 ... Corrugated metal plate mounting part, 19 ... Comb plate insertion hole, 20 ... Square comb plate, 21 ... Corner part.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-31790 (JP, A) Actually opened 62-86597 (JP, U) Actually opened 64-64797 (JP, U) Actually opened 6- 40899 (JP, U) Actual Kaihei 1-180699 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G21C 3/00

Claims (2)

(57) [Claims] 1. A substantially U-shaped outer frame covering one side of a fuel assembly and about half of two adjacent sides, and a comb plate inserted between each fuel rod of the fuel assembly attached to the outer frame. The outer frame and the comb plate are made of metal , and a corrugated metal plate is attached in the outer frame . 2. The corrugated metal plate is a wave formed on the outer frame.
Claim 1 fuel assembly transport separators according to characterized by comprising mounting in alignment folding shape metal plate mounting portion.