JPS60155995A - Pressure tube type reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a pressure tube nuclear reactor.

[Background of the invention]

The core of a pressure tube nuclear reactor is composed of a large number of pressure tube assemblies. FIG. 1 is a sectional view showing the configuration of a pressure tube assembly, with (a) showing the upper part and (b) showing the lower part.

The pressure pipe assembly 1 consists of a pressure pipe 2 and an upper extension pipe 3 and a lower extension pipe 4 connected above and below it, respectively, and is supported by an upper iron water shield 6 and a lower iron water shield 7 in the reactor core 5. has been done. The pressure tube assembly 1 stops the reactor coolant as an internal fluid and the thermal insulation gas as an external fluid, and has a fuel assembly 8, an upper shielding plug 9, and a lower shielding plug 1 inside.
It is a long tubular container having internal structures such as 0 and their supporting parts, and further equipped with a seal plug 11 attached to the lower end to be attached and detached at the time of fuel exchange. Then, the reactor coolant enters the inlet pipe nozzle 12 of the lower extension pipe 4 of the pressure pipe 2, boils and evaporates while cooling the fuel assembly 8 in the pressure pipe 20 section, and becomes a two-phase flow, and the reactor coolant enters the inlet pipe nozzle 12 of the lower extension pipe 4 of the pressure pipe 2. It exits from the tube 3 via an outlet tube nozzle 13 into an outlet tube (not shown). Therefore, inside the reactor core 5, which is made up of a large number of these pressure tube assemblies 1, an upper shielding plug 9 is located above the fuel assembly 8, and a lower shielding plug 10 is located below the fuel assembly 8.
A seal plug 11 is housed therein, and acts as a cylindrical primary slowing body with cooling channels to reduce radiation streaming from the core. This lower shield plug 10 is positioned at the lower end of the fuel assembly 8, supports the fuel assembly 8, has a connecting pipe 14 and a connecting pipe support rod (not shown), and has a cooling water flow path. It serves as a cylindrical primary retardation body to reduce radiation streaming from the core, and as a flow resistance body it provides the function of distributing flow to the core. In addition, the seal plug 11
has an upper guide pipe 15 and a lower guide pipe 16, and a plug with a seal is fixed to the opening of the pressure pipe lower extension pipe 4 for loading and unloading the fuel assembly 8 to seal the reactor coolant. be.

The lower shielding preg 10 and the seal plug 11 have an integrated structure.

Fuel exchange in a pressure tube nuclear reactor using such a pressure tube assembly 1 will be explained with reference to FIG.

In this figure, 1 is a pressure pipe assembly, 5 is a reactor core, 17 is a fuel exchange room, 18 is a traveling rail, 19 is a traveling trolley, 20
is a fuel exchanger, 21 is a pressure vessel, 22 itJ:Is port, 23 is a snout, 24 is a lower boat, 25 is a snout, 26 is a gripper, 27 is a transfer boat, 28
is an underground underwater transfer road, 29 is an underwater transfer machine, 30 is a fuel handling facility, 31 is a fuel exchange pool, 32 is a fuel loading/unloading machine,
33 is a transfer boat, and 34 is a fuel storage rack.

In the case of fuel exchange, the fuel exchanger 20 moved by the traveling trolley 19 is connected to the lower end of a predetermined pressure pipe assembly l, and the seal plug 11 and the lower shielding plug 1 are connected by a grab operation.
0 and the used fuel assembly 8 are pulled out and replaced with the fuel exchanger 20.
Then, a new fuel assembly 8 etc., which has been previously accommodated in the fuel exchanger 20, is inserted into the pressure tube assembly 1. The used fuel assemblies 8 and the like exchanged here are transported from the fuel exchange chamber 17 by an underwater transfer device 29 to a fuel exchange pool 31 via an underground underwater transfer passage 28, and are then discarded by a fuel inlet/output device 32. The fuel is transported to a fuel handling facility (not shown).

FIG. 3 is a sectional view of a main part showing details of the fuel exchanger, and FIG. 4 is a sectional view taken along line AA in FIG. In these figures, the same parts as in FIGS. 1 and 2 are given the same reference numerals. In these figures, 35 is a rotating drum type magazine assembly, 36 is a disk, 37 is a magazine tube, 38 is a bearing, 39 is a magazine stopper, 40 is an opening/closing operation mechanism, 41 is a gripper guide tube, '42 is a grab mechanism, Reference numeral 43 indicates a grab, and reference numeral 44 indicates a fuel assembly accommodated in the magazine tube 37. “Therefore, when performing fuel exchange in this way, the third
The length Ml of the magazine tube 37 or the length M2 of the lower guide tube 16 shown in the figure is the fuel assembly 8, the lower shielding plug 10, and the lower shielding plug 10 that the magazine tube 37 should contain. , and is determined by the length of the longest seal plug 11.

In addition, FIG. 4 shows the arrangement of the reactor core 5, pressure tube assembly 1, outlet pipes 4, 5, and □inlet pipe 46 of a pressure tube type nuclear reactor. 1, the inlet pipe 46 is connected to the upper extension pipe 3 and the inlet pipe 46 is connected to the lower extension pipe 4 in a tube group structure. Therefore, when the number of pressure pipe assemblies 1 increases as the size of the plant increases, the number of inlet pipes 46 connected to the lower extension pipe 4 also increases.
As a result, the dimension L1 required for the arrangement of the inlet pipe 46 in FIG.
increases, and accordingly, the dimension L2 of the pressure pipe lower extension pipe 4 increases, and the relationship between this and the dimension L3 of the fuel assembly 1 becomes L2>L8.

Therefore, the longest thing that the magazine tube 37 should contain is the lower 4 shielding plug 10, and the length Ml of this magazine tube 37 and the length M2 of the lower guide tube 16 are the length of the lower shielding plug 1°. It will depend on the situation.

As mentioned above, as the number of pressure pipes increases as the size of the plant increases, the L2 dimension becomes thicker, and as a result, the Ml
+M2 dimension becomes larger, resulting in an increase in the height of the fuel exchange chamber 17 shown by H in FIG. 2, and as a result, the position of the reactor core 5 in the reactor body becomes higher. 45, it is considered that the seismic resistance of the most important equipment piping such as the inlet pipe 46 during vibrations such as during an earthquake may be in a very severe condition.

[Purpose of the invention]

An object of the present invention is to eliminate such problems and provide a pressure tube nuclear reactor with high earthquake resistance and excellent fineness.

[Summary of the invention]

The present invention provides a fuel assembly, a lower shielding plug located above the fuel assembly, a lower shielding plug located below the fuel assembly,
It has a plurality of rectifying plates having a flow distribution function on its outer periphery, and includes a lower shielding plug and a plug having a communication pipe and a support rod for the communication pipe at the lower part, and an upper guide pipe and a lower guide pipe. A pressure tube type atom consisting of a plurality of pressure tube aggregates consisting of a pressure tube equipped with a removable seal plug at the lower end, and pressure/α upper and lower extension tubes connected to the upper part of the pressure tube. In the furnace, the lower shielding plug is divided into a plurality of divided lower shielding plugs in the longitudinal direction and stacked in multiple stages, and each of the divided lower shielding plugs has the rectifying plate on its outer periphery, and A stopper that supports the vertical load caused by the fuel assembly, the divided lower shielding plug, etc. is installed at a position opposite to the lower end of the rectifier plate of the divided lower shielding plug at the lowest stage of the inner peripheral surface of the pressure pipe. Here are some of the features.

The present invention provides that the earthquake resistance of equipment piping, etc. during earthquakes can be improved to a certain extent by lowering the installation height of those equipment piping, etc.
This was done with a focus on improving their health.
As mentioned above, by dividing the lower shielding plug into a plurality of parts and rotating each divided lower shielding plug and fuel assembly by the fuel exchanger grab mechanism to enable removal from the stopper, the lower shielding plug and the fuel assembly can be separated. The fuel assemblies can be attached and detached in short lengths, and as a result, the dimensions of the fuel exchanger magazine tube that accommodates them can be shortened, making it possible to achieve the intended purpose.

[Embodiments of the invention]

Examples will be described below with reference to FIGS. 6 to 26. Note that this example window is a case in which the number of divisions of the lower shielding plug and the fuel assembly is two. In these figures, the first to
The same parts as in FIG. 5 are given the same reference numerals, and the same parts in each figure are also given the same numbers.

FIG. 6 is a cross-sectional view showing the entire pressure tube assembly 1 of one example of a real lung, in which (a) shows the upper part, (b) shows the lower part, and 8a and 8b are each divided into two parts, each having its own length. divided fuel assemblies 10a and 1 of total length N, where N′ and N″
0b is a divided lower shielding plug with a total length M, and the lengths of the two halves are M' and M'', and L and O indicate the lengths of the seal plug 11 and the upper shielding plug 9, respectively. FIG. 7 shows details of part B in FIG.
FIG. 8 is an explanatory diagram showing the engaged state of FIG.
In these figures, 46 is a sleeve;
Reference numeral 7 indicates rectifier plates provided in multiple directions around the outer circumference of the divided lower shielding plug 10b. Lower shielding plug 10
The engaging portions a and 10b have an uneven shape in consideration of the shielding effect, and a protrusion 48 is provided on the convex surface of the divided lower shielding plug 10a for rotation prevention and positioning.
A recess that engages with the protrusion 48 is formed on the concave surface of the divided lower shielding plug 10b.

Further, Fig. 9 is a view from below of the upper part of the fuel assembly divided into two in the detail of part 0 in Fig. 6, and Fig. 10 shows the joined state of the two divided fuel assemblies 8a and 8b. F- in Figure 9
In these figures, 49a
and 49b, a spacer 5 to which the fuel assembly 8a is fixed;
0a and 50b are the intermediate type v-) which is integrated with a spacer, and the two divided fuel assemblies 83 and 8b are engaged with the intermediate tie plates 50a and 50b, and the middle +FAj tie plate 49a and 49b have a structure with slits in order to minimize the interference caused by the use of the intermediate tie plate in consideration of the cooling water flow path, and are made of a material with low neutron absorption. A protrusion 51 for stopping and positioning the fuel is provided on the central convex surface of the lower intermediate tie plate 50a, and a protrusion 52 located around the periphery, and a stopper 53 is provided on the middle iMJ tie plate 50b.

FIG. 11 is a diagram illustrating fuel exchange in a pressure tube reactor using such a pressure tube assembly, in which the fuel exchange chamber 17 is
The height H' of the fuel exchange chamber ρ is shorter than the height H of the conventional fuel exchange chamber ρ shown in FIG. Fuel exchange is carried out using the specified pressure pipe assembly 1.
The fuel exchanger 17 is connected to the lower end of the fuel exchanger 17, and the seal plug 11 and the divided lower shielding plugs 10a and 10 are connected by a grab operation.
b and the used divided fuel assemblies sa, sb are sequentially pulled out and stored in this fuel exchange machine 17, and then new divided fuel assemblies 8a, 8b previously housed in the fuel exchange machine 17 are extracted. etc. are inserted into the pressure tube assembly 1. The spent divided fuel assemblies 8a, 8b, etc. are transferred to the fuel exchange pool 31fi by running the fuel exchange machine 17 in the same way as in the conventional case shown in FIG. 2, and from there are carried out to the spent fuel handling facility. .

FIG. 12 is a sectional view showing details of the main part of the fuel exchanger 20, FIG. 13 is a sectional view taken along line GG in FIG. 12, and FIG.
Figure 2 is a cross-sectional view of the main part of the rotary machine groove for selecting the grab of the fuel exchanger, Figure 15 is a cross-sectional view taken along line H-H in Figure 14, and Figure 16 is the
4, □ FIG. 17 is a cross-sectional view taken along J-J in FIG. 14, and FIG. 18 is a cross-sectional view of a main part in a state different from that in FIG. 14. In these figures, 54 is a grab rotation drive mechanism;
5 is a grab lifting/lowering drive mechanism, 56 is a grab mechanism fixing plate, 5
7 is a rotary drive for selecting the grab mechanism! 41 + mechanism, 58 a protrusion, and 59 a gear.

The fuel exchanger 20 shown in FIG. 12 is housed inside a pressure vessel 21 mounted on a traveling trolley 19 shown in FIG. It has a grab rotation drive mechanism 54. As in the conventional case, the magazine assembly 35 is supported by upper and lower desks 36 via bearings 38 on the upper and lower sides.
and 36, and includes a plurality of magazine tubes 37 arranged on the same circumference. FIG. 13 shows a case where there are 14 magazine tubes 37. For example, 8 of these are used for new divided fuel assemblies and 2 are used for used divided fuel assemblies. for the sealing plug, and the rest for the exposed shielding plug. The magazine assembly 35 has a drive mechanism (as in the conventional case).
(not shown), the rotation is controlled to an arbitrary rotational position.

On the other hand, an upper guide tube 15 with a magazine assembly 35 sandwiched therebetween and a snout 23 attached above the pressure vessel 21 passes through the pressure vessel 21 and is fixed at a predetermined position on the same radius as the arrangement of the magazine tubes 37. A grab mechanism 42' including a grab 43' is disposed directly below the upper guide tube 15. The grab mechanism 42' is a seal plug grab mechanism 42' as shown in FIG.
a.

The three divided lower shielding plug grab mechanisms 42'b and the divided fuel assembly grab mechanisms 42'C are supported by the grab mechanism fixing plate 56 at positions shifted by 30 degrees in phase, for example. has been done.

The grab mechanism fixing plate 56 is rotationally controlled to a predetermined rotational position by the grab mechanism selection rotary drive mechanism 57.

Similarly, the grab 43' is a seal plug glove 43'a.
, the divided lower shielding plug grab 43'b, and the divided fuel assembly grab 43'C correspond to the three grab mechanisms 42'a, 42'b, and 42'C, respectively.
is included in. As shown in FIG. 14, the glove 43' is provided with a gear 59 at its lower end, and its rotation is arbitrarily controlled by a grab rotational mechanism 54. This glove rotation drive mechanism 54 can be attached to and detached from the glove 43'. Further, as shown in FIG. 15, the glove 43' is provided with a protrusion 58 on its lower outer circumferential surface, and is raised and lowered by a grab raising and lowering drive mechanism 55.

FIG. 14 shows a state in which the glove 43' is located at the lower end, and FIG. 18 shows a state in which the glove 43' is located at the upper end.

In addition, at another position shifted by 1800 degrees in phase from the grab 43', for example, a gripper guide tube 41 having an upper boat 22 at the top and a lower end thereof is located above the grab with the magazine assembly 35 in between. a divided fuel assembly 8a with a lower port 24;

Lower guide pipes 16 serving as elevating guide passages for the pressure vessels 8b and the like are fixedly installed so as to penetrate through the pressure vessels 21, respectively. Furthermore, the lower end of each magazine tube 37 is equipped with an open/close type magazine stopper 39 as in the conventional case, and two positions corresponding to the grab mechanism 42' and the lower guide tube 16 are equipped with Based on magazine stopper 39
A closing operation mechanism 40 for enclosing the pressure vessel 21 is arranged on the pressure vessel 21 side. This magazine stopper 39 fits into the magazine tube 37 yen! When carrying out a grab operation through the magazine tube 37, it is necessary to use the gripper 26. When lifting and suspending the fuel supply f+88, 8b which has been reduced by 1 Ift1 in the magazine tube 37, the magazine stopper 39 of the corresponding magazine tube 37 is opened.

Hereinafter, the procedure for refueling the -1fi nuclear reactor will be described.

First, the snout 23 is connected to the pressure tube assembly 1 of the reactor, and the seal plug 11 and the divided lower S shielding plug 10a are assembled by lifting and rotating the grab 43' and rotating the magazine assembly 350.

10b, the divided fuel assemblies 8a, 8b are drawn into the magazine tubes 37 of the valleys 1'' in this order, and then the new divided fuel assemblies 8a, 8b prepared in advance in another magazine tube 37 are inserted. Load the temple into pressure pipe assembly 1 Bong 1. While the glove 43' passes through the magazine tube 37 during this work process, the magazine stopper 39 is kept open by the opening/closing operation mechanism 40 according to a command. Next, the fuel transfer device 20 is moved and the transfer boat 27 is transferred to the underground underwater transfer passageway 28 at a delivery position 1a) to the lower boat 24. A disused divided fuel assembly Ba is housed.

Grab 8b. Here, the corresponding magazine tube 37
When the magazine stopper 39 is fully opened and the gripper 26 is operated, the fuel assembly Ba is divided through the lower system 1 ivy pipe 16 and the lower port 24.

8b etc. are suspended to the underwater transfer machine 29 and transferred.

After connecting the snout 23 to the pressure tube assembly 1 of the reactor, in order to draw the divided fuel assemblies 8a, 8b, etc. into the magazine tube 37, the snout 23 is connected to the pressure tube assembly 1 of the reactor. After connecting, the seal plug grab mechanism 42
'a is set at a predetermined position directly below the upper guide tube 15 by the rotation drive mechanism 57 for selecting a grab mechanism. Next, the magazine tube 37 for the seal plug is set in a predetermined position directly below the same upper guide tube 15 by rotation of the desk 36. Next, the seal plug glove 43'a is moved upward by φ by the grab lifting side 1lJJIfA mechanism 55, and after removing the seal plug 11 from the coffin 9, the grab lifting drive mechanism 55
to move downward. Next, the bottom plug grab mechanism 42'b is set at the position directly below the upper guide tube 15 by the grab mechanism selection rotary drive mechanism 57.
Next, the magazine tube 37 for the shielding plug is attached to the desk 3.
6, it is set in a predetermined position directly below the same upper guide tube 15. Next, the shielding plug grab 43'b is moved upward by the grab lifting/lowering drive mechanism 55, and when it reaches the position of the lower shielding plug 10, it is stopped by a command. Next, this grab 43'b is attached to the grab rotation part dJqA structure 5.
The lower shielding plug 10 is rotated to a predetermined position by 4, and after the lower shielding plug 10 is removed, it is moved downward by the grab elevating drive mechanism 55 and when it reaches the predetermined lowest position lft, the grab located below rotates. It is rotated to a predetermined position by a drive mechanism 55. This operation is similarly performed on all of the divided lower shielding plugs 1oa and iob. At this time, since the lower shielding plugs 10a and 10b are divided at C as shown in FIG. 6, the length accommodated in the magazine tube 37 of the fuel exchanger 20 is M.
′.

For example, the lower shielding plug 10a located below this
By pulling out the lower shielding plug 10b of the raft,
The fuel assemblies 8a and 8b located above the lower shielding plug 10b descend together with the 7-leaf plug 11 and the lower lower shielding plug 10a due to their own weight.
It is supported by the rectifying plate 59 of the upper lower shielding plug 10b at the position of the stopper 59 provided on the inner peripheral part of the pressure tube assembly 1 shown in FIG. 19, which shows the details of the D section in the figure.

FIG. 20 and FIG. 21, which shows a cross section thereof, show a state in which the lower shielding plug 10b is supported by a stopper 59 via a rectifier plate 47 provided on the outer periphery of the lower shielding plug 10b.
As shown in FIG. 21, a plurality of stoppers 59 are installed on the inner periphery of the pressure pipe so as to be at the same angle as the rectifying plate 47 so that the flow of the cooling water is not obstructed due to pressure loss or the like.

Next, the fuel exchanger grab 43' is attached to the cross-shaped groove provided on the bottom of the lower shielding plug 10b, and the fuel exchanger grab 43' is attached to the grab mechanism 42.
', the rectifying plate 47 installed on the lower shielding plug 10b is removed from the stopper 59, and the lower shielding plug 10b and the fuel assembly 8a and 8b are lowered. The sectional view in FIG. 22 shows the positional relationship between the stopper 59 and the current plate 47 provided on the outer periphery of the lower shielding plug 10b when it is removed from the stopper 59 and lowered. The position of the protrusion 53 of the divided fuel assembly 8b shown in FIG. For example, in the examples shown in FIGS. 21 and 9, the stopper 59, the current plate 47, and the protrusions 53 are installed at 60° intervals, and the current plate 47 and the protrusions 53 are arranged at cross angles of 30°. It is supported by the concave and convex parts.

Further, by the above-described operation, the divided lower shielding plugs 10a, 10b and the divided fuel assemblies 8a, 8b are
The fuel assembly 3a, 8b is separated and divided using the conventional fuel exchanging technique and is supported by the stopper 59 by the U'Ms object 53, and the lower shielding plug 10a is divided.

10b is accommodated in the fuel tank housing tube 37.

As shown in FIG. 6, the fuel assembly 8 has 0 parts 8a and 8b.
The dimensions are N' and N, respectively.
As shown in FIGS. 9 and 10, the installation angle of the protrusion 52 is offset by 30 degrees from the protrusion $53 of the lower fuel assembly 8b, and the lower fuel assembly 8a is Even in the separated state, the upper fuel assembly 8b is supported by the stopper 59 by the protrusion 53.The separated lower fuel assembly 8a is accommodated in the fuel exchanger magazine tube 37 in the same manner as described above. .

Finally, rotate the remaining upper fuel assembly 8b by 30 degrees, and with the protrusion 52 removed from the stopper 59,
It is pulled out in the same manner as described above and stored in the fuel machine magazine tube 37.

Next, step V of the fuel loading method for this pressure-# type nuclear reactor.
Let me explain in detail. Divided fuel assemblies 8a, 8b,
The lower shielding plug 10a is divided into 1 parts.

10b is loaded into the pressure tube assembly 1 in the reverse order of the above-mentioned 11= order, and the fuel assembly is loaded in the situation where the rectifier plate 47 installed on the lower fA transport plug 10a is supported by the stopper 59. Body 10a, 10b, lower shielding plug lQa, 10
b is installed in one piece.

Next, the seal plug 11 is installed in the lower shielding plug 10H using a method similar to the conventional method. FIG. 23 is a cross-sectional view showing how the seal plug is installed in the pressure tube assembly 1, FIG. 24 is a 1-LllEfr side view of FIG. 16, and FIG. FIG. 26 is a sectional view taken along the line MM in FIG. 25. In these diagrams, 60 is the consecutive weight, 6
1 and 62 are springs, 63 is a connecting pipe support rod, 6
4 indicates a bolt. As shown in these figures, the seal plug lower guide tube 16 and the inner surface of the pressure tube are formed with slits (Iq) to prevent the seal plug 11 from rotating within the pressure tube assembly 1 and to prevent the seal plug 11 from rotating within the pressure tube assembly 1. Connecting pipe support rod 63 and seal plug 1 of plug 10a
The upper guide tube 15 of No. 1 also has a similar slit structure to prevent the lower shielding plug 10a and the seal plug 11 from rotating relative to each other.

Therefore, according to this structure, the fuel assembly 8a.

8b, lower shielding plug toa, 10b, and seal plug 11 can all be prevented from rotating, so it is possible to prevent angular deviations when each is pulled out.

That is, according to this embodiment, the fuel assembly 8a, 8b is divided into two parts, the lower shielding plug 10a is divided into two parts,
10b can be independently pulled out and loaded from the pressure tube assembly 1, so that the dimensions of the magazine tube 37 can be shortened.

In this embodiment, the lower shielding plug and the fuel assembly are divided into two in the longitudinal direction, and a stopper is provided on the outer periphery of the lower shielding plug and the fuel assembly, and a stopper is provided on the inner peripheral surface of the pressure pipe at the lower end of the rectifier plate of the lowermost lower shielding plug. A stopper is installed and the structure is designed to support the vertical load such as the weight of the fuel assembly and lower shielding plug, and the lower shielding plug and fuel assembly, which are divided into two parts, are rotated by the fuel exchanger plug mechanism and removed from the stopper. As a result, the shielding plug and fuel assembly can be delaminated in a short length, and as a result, the dimensions of the fuel exchanger magazine tube that accommodates them can be shortened, so the height of the entire refueling machine can be reduced. As shown in Fig. 11, the height H of the fuel exchange chamber can be reduced to H', and as a result, the core position can be moved closer, and the earthquake resistance of equipment piping, etc. can be improved, and the soundness can be improved. This has the effect that the fuel conversion chamber can be made smaller, so that the entire reactor building can also be made smaller.

〔Effect of the invention〕

The present invention makes it possible to provide a pressure tube nuclear reactor with high earthquake resistance and excellent soundness, and has great industrial effects.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the pressure tube assembly of a conventional pressure tube reactor, Figure 2 is an explanatory diagram of the fuel exchange method, Figure 3 is a sectional view of the main parts of the fuel exchange machine, and Figure 4 is A-A in Figure 3
Similarly, FIG. 5 is a vertical cross-sectional view showing the structure near the reactor core including the entry and exit pipes, and FIG. 6 is the pressure pipe 2 of the present invention! ! 7 is a sectional view of the main part showing the securing state of the lower shielding plug, which is also divided into two parts. −
A plan view in the direction of arrow E, FIG. 9 is a plan view of the upper part of the fuel assembly divided into two, and FIG. 10 is a main part showing the engaged state of the fuel assembly divided into two. 11 is an explanatory diagram of the fuel exchange method, FIG. 12 is a sectional view of the main part of the fuel exchange machine, FIG. 13 is a sectional view taken along the line G-G in FIG. 12, and FIG. 14 is an illustration of the fuel exchange method. 15 is a sectional view of the main part of the plug rotation mechanism of the exchanger, FIG. 15 is a sectional view taken along the line H-H in FIG. 18 is a sectional view of the main part in a state different from that in FIG. 14, FIGS. 19 and 20 are sectional views showing details of the D section in FIG. 6 in different states, and FIG. 20 - sectional view taken along the arrows,
FIG. 22 also shows the K − of FIG. 20 in different states.
23 is a sectional view of the main part showing the installed state of the seal plug, FIG. 24 is a sectional view taken along the line L-L in FIG. 23, and FIG. 25 is a sectional view of the lower shielding plug and the seal. Figure 26 is a sectional view of the lower part showing the installed state of the plug.
It is a sectional view taken along the line MM in the figure. DESCRIPTION OF SYMBOLS 1... Pressure tube assembly, 2... Pressure pipe, 3... Upper extension tube, 4... Upper extension tube, 5... Nuclear P reactor core, 6
... Upper iron water shielding body, 7... Lower iron water shielding body,
8... Fuel assembly, 8a, 8b... Divided fuel assembly, 9... Upper shielding plug, 10... Lower shielding plug, ioa. 10b...Divided lower shielding plug, 11...
Seal plug, 12... Inlet pipe nozzle, 13... Outlet pipe nozzle, 14... Connecting pipe, 15... Upper guide pipe, 16... Lower guide pipe, 20... Fuel exchanger, 21
...pressure vessel, 22-...l-Is boat, 23.
...Snout, 24...Lower hoard, 25...Snout, 26...Gripper, 35...Rotating drum type magazine assembly, 36...Disc, 37...Magazine tube, 38...・Bearing, 39... Magazine stopper, 40... Opening/closing operation mechanism, 41... Grip guide tube, 42'... Grab mechanism, 43'... Grab,
44...Fuel combination housed in magazine tube, 4
5... Outlet pipe, 46... Inlet pipe, 47... Current plate, 48... Projections, 49a, 49b... Spacer,
50a, 50b... intermediate tie plate, 51.52.
... Protrusion, 53... Stopper, 54... Grab rotation drive mechanism, 55... Grab lifting/lowering drive mechanism, 56...
- Grab mechanism fixing plate, 57... Rotary drive mechanism for grab mechanism selection, 58... Protrusion, 59... Gear, 60...
... Connecting rod, 63... Connecting pipe support rod. Agent Patent attorney Hiroo Nagasaki No. 3 Tomoe Kaya 1st 70 8th figure 1z Figure $14 Hardest 150 Kaya 160 Kaya I July + 54 $18 Kuchihaya 19 2nd figure 20 $210 06 $zz Hardest 10th Kaya 23 Kuchihaya 24 - continuation of page 1 0 Inventor Noriyoshi Sueyoshi 3-chome, Saiwaimachi, Hitachi City 0 Inventor Kiyoshi Ishikawa 3-chome, Saiwaimachi, Hitachi City Inventor Isao Koguchi Mari, Hitachi City Within 3-chome

Claims (1)

[Claims] 1. A fuel assembly, an upper shielding plug located above the fuel assembly, and a plurality of rectifying plates located below the fuel assembly and having a flow distribution function on the outer periphery thereof. A pressure pipe having a lower end containing a lower shielding plug having a communication pipe and a support rod for the communication pipe, and having a removable sealing plug having an upper guide pipe and a lower guide pipe attached to the lower end; In a pressure tube type nuclear reactor comprising a plurality of pressure tube assemblies constituted by upper and lower pressure tube extension tubes connected above and below the pressure tube, the lower shielding plug has a plurality of pressure tubes arranged in the longitudinal direction of the lower shielding plug. consisting of divided lower shielding plugs that are divided into and stacked in multiple stages, each of which has the rectifying plate on its outer periphery, and the lowermost divided lower shielding plug on the inner circumferential surface of the pressure pipe. A pressure tube nuclear reactor characterized in that a stopper is installed at a position facing the lower end of the current plate to support the vertical load caused by the fuel assembly, the divided lower shielding plug, etc. 2- @Me lower lower part - the plug and the fuel assembly are
A pressure tube nuclear reactor according to claim 1, which is divided into two parts.