JPH01250093A - Nuclear fuel rod - Google Patents

Abstract

PURPOSE:To prevent misloading even when there are various kinds of enrichment by changing combinations of the width, length, and height of a rib for misloading prevention according to the enrichment of the nuclear fuel rod. CONSTITUTION:The rib 2 for misloading prevention and a rib 3 for rotation prevention are formed on the outer peripheral surface of the rear end part of the nuclear fuel rod 1 for a high-temperature gas furnace which is sectioned nearly circularly. The height H, width W, and length L of the rib 2 are varied according to the enrichment of nuclear fuel. A groove 6 (not shown in figure) of size corresponding to the rib 2 is formed in the nuclear fuel rod insertion hole of a graphite block 5 (not shown in figure). When a different fuel rod 1 is inserted into the insertion hole 5, the rear end of the fuel rod 1 projects from the graphite block 5 or an abnormal gap is formed between the groove 6 and rib 2, so the misloading is decided visually clearly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a nuclear fuel rod, and more particularly to a nuclear fuel rod that can be accurately inserted into a predetermined nuclear fuel rod insertion hole of a graphite block.

[Prior art and problems to be solved by the invention] Currently, in pinyin block type fuel assemblies for high-temperature gas reactors, nuclear fuel rod insertion holes provided in hexagonal graphite blocks are nuclear fuel rods of a predetermined enrichment must be inserted into the

Therefore, special measures are required to prevent nuclear fuel other than the nuclear fuel rods defined in the predetermined nuclear fuel rod insertion holes from being erroneously loaded.

That is, the width and length of the anti-rotation rib attached to the rear end of the nuclear fuel rod, and the width and length of the groove corresponding to the rib provided in the nuclear fuel rod insertion hole into which the nuclear fuel rod must be inserted. By designing the dimensions of the ribs and the grooves so that they match, and by making the designs different depending on the enrichment of the fuel rod, a specific nuclear fuel rod insertion hole is provided with an enrichment that does not correspond to the enrichment. This prevents incorrect loading of nuclear fuel rods by inserting other nuclear fuel rods at the same time.

For example, nuclear fuel rods for high enrichment use have wider and shorter ribs to prevent rotation, while nuclear fuel rods for lower enrichment use have narrower ribs and longer ribs. The dimensions of the ribs are determined in stages so that the corresponding nuclear fuel rod insertion holes are designed so that the grooves have the same width and length as the enrichment rib dimensions. By doing so, it is mechanically controlled so that nuclear fuel rods of a specific enrichment are inserted only into the corresponding nuclear fuel rod insertion holes.

If a nuclear fuel rod is mistakenly inserted into the wrong position of the nuclear fuel rod insertion hole, the nuclear fuel rod will not be inserted into the nuclear fuel rod insertion hole at the correct position, and the rear end of the fuel rod will protrude from the nuclear fuel rod insertion hole entrance. Otherwise, the rear end of the nuclear fuel rod cannot be inserted at all, so incorrect loading can be detected by appearance.

However, as the enrichment level increases, the number of combinations of nuclear fuel rods and corresponding nuclear fuel rod insertion holes increases, so there is a dimensional limit to simply changing the width and length of the ribs to prevent one rotation. , the number of combinations cannot be sufficiently accommodated, resulting in erroneous placement.

An object of the present invention is to provide a nuclear fuel rod that can be accurately inserted into a predetermined nuclear fuel rod insertion hole provided in a graphite block even when the nuclear fuel rod has various enrichments. .

[Means for Solving the Problems] The present invention for solving the problems described above has a width, length and height different from those of other nuclear fuel rods depending on the enrichment level, and the end faces of the nuclear fuel rods are different from those of other nuclear fuel rods depending on the enrichment level. A specific nuclear fuel which is provided with a lip for preventing erroneous loading at its rear end that matches the rear end surface of the rod, and has a groove corresponding to the rib for preventing erroneous loading in a plurality of nuclear fuel rod insertion holes provided in a graphite block. This nuclear fuel rod is characterized in that it can be inserted into a rod insertion hole.

In the present invention, three parameters consisting of the width, length, and height of the rib for preventing erroneous loading are changed depending on the enrichment level of the nuclear fuel rod.

How the width, length, and height of the ribs are changed is arbitrary.

Therefore, any number of nuclear fuel rods with ribs for preventing misloading having dimensions corresponding to the enrichment can be used.

In addition, since nuclear fuel rods must be inserted into specific nuclear fuel rod insertion holes depending on the enrichment level, it is necessary to insert a plurality of nuclear fuel rod insertion holes provided in the graphite block into corresponding ribs to prevent incorrect loading. It is necessary to form a groove of width, length and depth. However, the shape of the rib to prevent incorrect loading and the shape of the groove of the nuclear fuel rod insertion hole are not required to match completely, but when a predetermined corresponding nuclear fuel rod is inserted into the nuclear fuel rod insertion hole , the groove has a shape that allows the inner wall of the groove to substantially match the outer surface of the rib for preventing erroneous loading, and the rib for preventing erroneous loading to be housed in the groove without creating wasted space. It's fine if you do.

[Function] According to the above configuration, the width and depth of the groove in the nuclear fuel rod insertion hole provided in the graphite block match the width and height of the rib for preventing erroneous loading in the nuclear fuel rod. Even if the nuclear fuel rod is inserted into the nuclear fuel rod insertion hole, the length of the groove and the length of the rig do not match, so the rear end of the nuclear fuel rod has a graphite block nuclear fuel rod insertion hole. If the nuclear fuel rod protrudes from the plane or the rear end of the nuclear fuel rod enters the nuclear fuel rod insertion hole of the graphite block too much, it can be determined that the nuclear fuel rod has been incorrectly loaded into the nuclear fuel rod insertion hole.

Even if the width and length of the groove in the nuclear fuel rod insertion hole provided in the graphite block match the radius and length of the rib to prevent incorrect loading on the nuclear fuel rod, the nuclear fuel rod When attempting to insert a nuclear fuel rod into the insertion hole, if the depth of the groove is smaller than the height of the rib, the nuclear fuel rod cannot be inserted into the insertion hole; When the length dimension is larger than the height dimension of the rib, the nuclear fuel rod can be inserted into the nuclear fuel rod insertion hole, but there is a large gap between the rib and the groove in the depth direction within the groove. In any case, it can be determined that this nuclear fuel rod has been erroneously loaded into the nuclear fuel rod insertion hole.

Even if the depth and length of the groove in the nuclear fuel rod insertion hole provided in the graphite block match the height and length of the rib to prevent incorrect loading on the nuclear fuel rod, When attempting to insert a nuclear fuel rod into a nuclear fuel rod insertion hole, if the width of the groove is smaller than the width of the rib, the nuclear fuel rod cannot be inserted into the nuclear fuel rod insertion hole; When the dimension is larger than the width dimension of the rib, the nuclear fuel rod can be inserted into the nuclear fuel rod insertion hole, but a large gap is created between the rib and the groove in the width direction of the groove. In any case, it can be determined that this nuclear fuel rod has been erroneously loaded into the nuclear fuel rod insertion hole.

In this way, by changing the height of the rib provided at the rear end of the nuclear fuel rod to prevent erroneous loading, the width of the rib to step B, and the length of the rib to step C, (aXbXc
) Ribs are formed to prevent incorrect loading of nuclear fuel rods corresponding to the enrichment of the stage.

Therefore, even if the enrichment level increases dramatically, according to the present invention, incorrect loading of nuclear fuel rods can be effectively prevented.

[Example 1] The present invention will be explained in further detail by showing examples of the present invention below.

Figures 1 and 2 show the structure of the ribs for preventing erroneous loading.

As shown in FIGS. 1 and 2, a rib 2 for preventing erroneous loading having dimensions of height H, [W and length L is provided on the outer circumferential surface of the rear end of a nuclear fuel rod 1 having a substantially circular cross section. is formed to protrude. Note that 3 is a rib for preventing rotation.

In the present invention, the dimensions of the height H1 width W and length L of the rib 2 for preventing erroneous loading are changed according to the enrichment of the nuclear fuel. This is intended to prevent incorrect loading.

- For example, as shown in Figure 3, for the first nuclear fuel rod 1a with high enrichment, the width of the rib 2a for preventing incorrect loading is Wl, the height is Hl, and the length is As shown in FIG. 4, the high enrichment first nuclear fuel rod 1
Regarding the second nuclear fuel rod 1b whose enrichment level is lower than a, the width of the rib 2b for preventing erroneous loading is set to W2 (W2 <Wl
), its height is set to H2 (H2<Hl), and its length is set to Lp (L2<t,), and as shown in FIG. 5, the enrichment is lower than that of the second nuclear fuel rod 1b. Third
The nuclear fuel rod 1c has a rib 2C to prevent its incorrect loading.
(7) Set the width to W3 (W3 < W2 ), the height to H3 (H3 < H2), and the length to L3 (L3 <
L2).

Regarding the nuclear fuel rod insertion hole provided in the graphite block 5, as shown in FIG. 6, the first nuclear fuel rod insertion hole into which the first nuclear fuel rod la is inserted has a width slightly larger than Wl and a depth. Set the value to 1+.

A groove 4a having a length slightly larger than Ll is provided, and as shown in FIG.
The second nuclear fuel rod insertion hole into which b is inserted has a width slightly larger than W2, a depth of 2, and a length of L2.
As shown in FIG. 8, the third nuclear fuel rod insertion hole into which the third nuclear fuel rod 1c is inserted is provided with yI4b, which has a width slightly larger than W3 and a depth 23, and a groove 4C having a length slightly larger than L3 is provided.

In the first to third nuclear fuel rods 1a to 1c, each of the ribs 2a to 2c for preventing erroneous loading is provided in a straight line with one rib 3 of the three ribs for preventing rotation. Therefore, the dimension Jl+ is set such that the sum of the illiteracy and the radius of the first nuclear fuel rod insertion hole is slightly larger than the sum of the radius of the first nuclear fuel rod 1a and the aforementioned H1,
．． The dimensions of 3 are set in the same manner.

Therefore, originally, when the first nuclear fuel rod 1a is inserted into the first nuclear fuel rod insertion hole, the rear end surface of the first nuclear fuel rod la coincides with the flat end surface of the graphite block 5, but for example, the rear end surface of the first nuclear fuel rod la coincides with the flat end surface of the graphite block 5. When inserting the first nuclear fuel rod 1a into the second nuclear fuel rod insertion hole, the width of the groove 4b in the second nuclear fuel rod insertion hole is different from the width of the rib 2a for preventing incorrect loading in the first nuclear fuel rod 1a. The rib 2a of the nuclear fuel rod 1a gets stuck, and the rear end of the :51 nuclear fuel rod 1a protrudes from the flat end surface of the graphite block 5, so that the first nuclear fuel rod 1a cannot enter the second nuclear fuel rod insertion hole any further.

Therefore, incorrect loading of the first nuclear fuel rod 1a can be visually and clearly determined.

Furthermore, when the third nuclear fuel rod IC is inserted into the first nuclear fuel rod insertion hole, the radius W3 of the rib 2C for preventing erroneous loading is smaller than the width of the groove 4a in the first nuclear fuel rod insertion hole. , this rib 2C enters into the groove 4a, but the length of this groove 4a is approximately equal to Ll,
Since the rib length H3 is shorter than the rib length H3, when the rib 2C is housed in the groove 4a, the rear end of the first nuclear fuel rod 1a protrudes from the flat end surface of the graphite block 5, and no further The third nuclear fuel rod 1c is located within the first nuclear fuel rod insertion hole height.
(See Figure 9).

Therefore, incorrect loading of the third nuclear fuel rod 1c can be visually and clearly determined.

In addition to the above examples, the rib dimensions can also be determined as follows.

As shown in Fig. 10, for the fourth nuclear fuel rod 1d with low enrichment, the width of the incorrect loading prevention rib 2d is set to H4, the height is set to H4, and the length is set to H4. As shown in FIG. 11, for the fifth nuclear fuel rod 1e whose enrichment is higher than the fourth nuclear fuel rod 1d with a low enrichment, the width of the rib 2e for preventing incorrect loading is set to H4, and its height is set to H4. H5 (H4<
Hs) and the length is set to H4, and as shown in FIG. 12, for the sixth nuclear fuel rod if, which has a higher cilii degree than the fifth nuclear fuel rod 1e, a rib for preventing erroneous loading is provided. Set the width of 2f to H4, the height to H6 (H5<H6), and the length to H4.

That is, in the ribs 2d to 2f for preventing incorrect loading of the fourth to sixth nuclear fuel rods 1d to 1f, the radius W4 and the length H4 are equal to each other, and only their heights are different.

As for the various nuclear fuel inlet holes provided in the graphite pool A75, as shown in Fig. 13, the width of the fourth nuclear fuel rod insertion hole into which the fourth nuclear fuel rod 1d is inserted is slightly larger than H4. , depth to 1g.

A groove 4d whose length is slightly larger than H4 is provided, and as shown in FIG. 14, the fifth nuclear fuel rod insertion hole into which the fifth nuclear fuel rod 1e is inserted has a width slightly larger than H4. Larger dimensions, depth 25 and length H
As shown in FIG. 15, the third nuclear fuel rod insertion hole into which the third nuclear fuel rod 1c is inserted is provided with a groove 4e having a width slightly larger than H4. A groove 4c is provided with a depth set to 6 and a length slightly larger than H4.

Note that in the fourth to sixth nuclear fuel rods 1d to 1f.

Each of the ribs 2d to 2f for preventing erroneous loading is provided in a straight line with one rib 3 of the three ribs for preventing rotation. Therefore, the above dimensions! ; L4 is the sum of 4 and the radius of the ml nuclear fuel rod insertion hole, which is the radius of the fourth nuclear fuel rod 1d and the H
4, and is set to be slightly larger than the sum of dimension 5. The dimensions of the intersection 6 are also set in a similar manner.

Therefore, originally, when the fourth nuclear fuel rod 1d is inserted into the fourth nuclear fuel rod insertion hole, the rear end surface of the fourth nuclear fuel rod ld would coincide with the flat end surface of the graphite block 5, but for example, When inserting the fourth nuclear fuel rod 1d into the fifth nuclear fuel rod insertion hole, the height fL of yt4e in the fifth nuclear fuel rod insertion hole
5 and the radius of the fifth nuclear fuel rod insertion hole is the fourth nuclear fuel rod 1.
d is larger than the sum of the height H4 of the rib 2d for preventing erroneous loading and the radius of the fourth nuclear fuel rod 1d.
d is accommodated in the groove 4e. However, an abnormal liJI gap is generated between the top surface of the rib 2d and the bottom surface of the groove 4e.

Therefore, incorrect loading of the fourth nuclear fuel rod 1d can be visually and clearly determined.

Furthermore, when the second and fifth nuclear fuel rods 1e are inserted into the fourth nuclear fuel rod insertion hole, the sum of the height H5 of the rib 2e for preventing erroneous loading and the radius of the fifth nuclear fuel rod 1e is the groove in the fourth nuclear fuel rod insertion hole. Since the dimension is larger than the sum of the height is of 4d and the radius of the fourth nuclear fuel rod insertion hole, this rib 2e is held against the flat end of the graphite block 5, and the fifth nuclear fuel rod 1e is inserted into the aforementioned 1a4d.
The rear end of the fifth nuclear fuel rod 1e protrudes from the flat end of the graphite block 5 (see FIG. 16).

Therefore, incorrect loading of the fifth nuclear fuel rod 1e can be visually and clearly determined.

Incidentally, when trying to insert the sixth nuclear fuel rod if into the fourth nuclear fuel rod insertion hole or the fifth nuclear fuel rod insertion hole, incorrect loading can be similarly visually determined.

[Effect of the Invention J According to the present invention, the width, height, and length of the ribs for preventing erroneous loading in the nuclear fuel rods are set according to the enrichment of the nuclear fuel. The number of combinations with ribs to prevent incorrect loading has increased dramatically,
As a result, even if the nuclear fuel enrichment levels in the nuclear fuel rods vary widely, it is possible to easily detect incorrect loading of nuclear fuel rods into predetermined nuclear fuel rod insertion holes provided in the graphite block.

Therefore, according to the present invention, the nuclear fuel rod can be accurately inserted into the nuclear fuel rod insertion hole.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the structure of the rib for preventing incorrect loading of the present invention, FIG. 2 is a side view showing the rear end of the nuclear fuel rod having the rib, FIGS. 3 to 5, and 10 to 12. Each figure is a front view showing another example of the rib for preventing erroneous loading of the present invention, and tJS6 to 8 and 13 to 15 are examples of the nuclear fuel rod insertion hole of a graphite block of a nuclear fuel rod having ribs. -g8 cross-sectional explanatory view showing the state housed in the interior, and FIGS. 9 and 16 are partial cross-sectional explanatory views for showing the operation of the present invention. 1, la, lb, lc, ld, le, le. l f ...---- Nuclear fuel rod, 2.2a, 2b,
2c. 2d, 2e, 2f... Rib for preventing incorrect loading, 3... Rib for preventing rotation, 4a, 4
b. 4c, 4d, 4e, 4f, groove, 5.
・・・・・・Graphite block. Figure 1 Figure 2 Figure 3 Figure 6 Figure 4 Figure 7 Figure 5 Figure 8 Figure 9

Claims (1)

[Claims] different widths than in other nuclear fuel rods, depending on the enrichment;
A rib for preventing erroneous loading, which has a length and height and whose end face coincides with the rear end face of the nuclear fuel rod, is provided at the rear end, and the rib is provided at the rear end to prevent misloading. A nuclear fuel rod characterized in that it can be inserted into a specific nuclear fuel rod insertion hole having a groove corresponding to a rib for preventing erroneous loading.