JPH0755383A - Structure for supporting heat transfer tube for steam generator - Google Patents

Abstract

PURPOSE:To improve supporting strength by a method wherein a plurality of outwardly attached perforated plates are arranged on the outer surface of a cylindrical inner wall through the through holes of the outwardly attached perforated plates while inwardly attached perforated plates are arranged integrally with the inner surface of a cylindrical outer wall between the outwardly attached perforated plates through the through holes of the inwardly attached perforated plates. CONSTITUTION:When a plurality of layers of heat transfer tube 27 are arranged, the heat transfer tube 27, positioned at inside relatively, are provided sequentially through the outwardly attached perforated plates 31, attached to the outer surface of a cylindrical inner wall 25 with a space circumferentially. In this case, the heat transfer tubes 27 at the outside are provided alternately through the through holes 31a, 32a so as to interpose the inwardly attached perforated plates 32 between the outwardly attached perforated plates 31. The heat transfer tubes 27 for all layers are bent so as to have a helical coil shape and, thereafter, the outside parts of the inwardly attached perforated plates 32 are attached integrally to the inner surface of the cylindrical outer wall 24 through coupling devices 33. According to this method, the supporting strength can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support structure for a heat transfer tube for a steam generator, and more particularly to improving the support strength of the heat transfer tube and suppressing the occurrence of fluid vibration.

[0002]

2. Description of the Related Art FIG. 2 is a Japanese Unexamined Patent Publication No. 3-252593 (fuel assembly exchange device), Japanese Unexamined Patent Publication No. 3-252594 (fuel assembly exchange device), and Japanese Unexamined Patent Publication No. 3-25259.
5 shows an example of a light water cooled nuclear reactor described in Japanese Patent Publication No. 5 (fuel assembly exchange device).

In FIG. 2, reference numeral 1 is a reactor pressure vessel,
2 is a core, 3 is a steam generator, 6 is a primary cooling water pump, 1
Reference numeral 5 is a riser pipe, 16 is a poison tank, 17 is a cooling water inlet, 18 is a hydraulically operated valve, 19 is a poison distributor, and P is boric acid water (pool water in the furnace).

In the nuclear reactor having such a structure, the primary cooling water and the boric acid water P flow differently (circulate) as described below depending on the difference between the operation and the stop of the pump.

During operation, the primary cooling water passes through the core 2, the riser pipe 15, the primary cooling water pump 6, the steam generator 3, and the cooling water inlet 17, as shown by the solid arrow in FIG. However, the boric acid water P is isolated by the hydraulically operated valve 18 and the poison distributor 19 to prevent the phenomenon of insertion and the phenomenon of mixing.
Therefore, the steady operation state is maintained without changing the boric acid water concentration in the primary cooling water.

When the primary cooling water pump 6 is stopped, the steam generator 3 is not fed, and when the discharge pressure drop of the primary cooling water pump 6 is detected, the hydraulically operated valve 18 opens the pipeline. In addition, since the primary cooling water continuously heated in the core 2 rises, the raised primary cooling water is sent out to the inside of the poison tank 16 as shown by a dashed arrow in FIG. The boric acid water P flows into the core 2 via the poison distributor 19 and the concentration of boric acid in the core 2 increases, whereby the fission reaction is suppressed and the suspension is led to a natural stop.

In such a reactor of FIG. 2, the inside and outside of the poison tank 16 are surrounded by the primary cooling water at a high temperature, and the boric acid water P based on the heat output of the reactor is The volume of liquid changes due to expansion and contraction.
At the portion of the poison distributor 19, the boundary between the primary cooling water and the boric acid water P is likely to change, and the controllability of the reactor output is likely to be impaired.

Next, FIG. 3 shows another structural example (plan example) of the light water cooling type reactor. In the plan example, the reactor pressure vessel 1 is placed in the pool water W of the reactor containment vessel 21 in a state of being immersed in water, and the poison tank 22 is also placed in the pool water W. And the reactor pressure vessel 1
The poison tank 22 and the poison tank 22 are connected by a liquid supply system pipe 23.

With this structure, the poison tank 22 is housed in the pool water W in a low temperature state, and the thermal isolation from the reactor pressure vessel 1 and the isolation between the primary cooling water and the boric acid water P are performed. By carrying out the setting and supplying the boric acid water P using the drop and the specific gravity difference and merging the boric acid water P at the lower position of the circulation flow of the primary cooling water,
At the time of actuation of the hydraulically operated valve 18, high-concentration boric acid water can be fed into the reactor core 2 from below as shown by the arrow in FIG. 3 to promptly bring the reactor to a natural shutdown state.
It is possible to improve the safety by increasing the capacity of the boric acid water P.

The steam generator 3 incorporated in the nuclear reactor of FIG. 3 is installed in the annular space between the reactor pressure vessel 1 and the riser pipe 15. The steam generator 3 is shown in FIG.
Further, as shown in FIG. 5, the cylindrical outer wall 24 and the cylindrical inner wall 25 arranged concentrically, and the primary cooling water formed between the cylindrical outer wall 24 and the cylindrical inner wall 25 are inserted downward. The heat exchange chamber 26, a plurality of helical coil-shaped heat transfer pipes 27 arranged in parallel inside the heat exchange chamber 26, a feed water inlet 28 and a steam outlet 29 connected to these heat transfer pipes 27, and a cylindrical inner wall A plurality of perforated plates 30 that are integrally attached to the outer surface of 25 at intervals in the circumferential direction by welding or the like and are in close proximity to the cylindrical outer wall 24; 30a.

In the heat transfer tube 27 of such a steam generator, while the perforated plate 30 is attached to the cylindrical inner wall 25, the work of passing the pipe in a spiral shape sequentially while bending the pipe, It is assembled by a method such as repeating for the parallel layers.

[0012]

However, since the plurality of perforated plates 30 are necessarily arranged radially as shown in FIG. 5, the support pitch of the heat transfer tubes 27 becomes large at the outer position. The strength tends to decrease. In this case, increasing the number of the perforated plates 30 to reduce the support pitch at the outer position makes the support pitch at the inner position smaller, which is large due to the difference in thermal expansion between the heat transfer tube 27 and the perforated plate 30. Since thermal stress is often generated, there is a limit to the number of perforated plates 30 that can be installed in the conventional structure. Therefore, there remains a problem that fluid vibration is likely to occur at the outer position.

The present invention effectively solves the above problems, and an object thereof is to improve the support strength and suppress the occurrence of fluid vibration without impairing the assembling property of the heat transfer tube.

[0014]

As means for solving such a problem, a heat exchange chamber is defined between a cylindrical outer wall and a cylindrical inner wall, and a helical coil heat transfer tube is provided inside the heat exchange chamber. In the case of a steam generator in which is arranged a plurality of outward perforated plates in which the heat transfer tubes are inserted into the through holes, which are arranged in proximity to the cylindrical outer wall with a circumferential interval on the outer surface of the cylindrical inner wall. A plurality of inward perforated plates which are arranged between the outward perforated plates integrally with the inner surface of the cylindrical outer wall and at intervals in the radial direction with respect to the cylindrical inner wall and through which the heat transfer tubes are inserted into the through holes. The configuration is adopted.

[0015]

When the heat transfer tubes are arranged in the shape of a multi-layer helical coil, the heat transfer tubes located relatively inside and the heat transfer tubes located relatively outside are attached differently. In the inner heat transfer tube, a plurality of outward perforated plates are arranged at intervals in the circumferential direction on the outer surface of the cylindrical inner wall so that the through holes are inserted, and the outer heat transfer tube is The plurality of inwardly directed porous plates are interposed between the plurality of outwardly directed porous plates, the heat transfer tubes are inserted through the through holes, and the inwardly directed porous plates are integrally attached to the inner surface of the cylindrical outer wall. The support distance of the heat transfer tube at the outer position is reduced by inserting the through holes of both porous plates, and the supporting strength is secured by attaching the inward porous plate to the cylindrical outer wall.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a heat transfer tube support structure for a steam generator according to the present invention will be described below with reference to FIG. Also in this embodiment, the present invention is applied to a light water cooling type reactor in which the reactor pressure vessel 1 is placed in the pool water W of the reactor containment vessel 21 shown in FIG.

In FIG. 1, reference numeral 31 is an outward porous plate, 3
2 is an inward porous plate, and 33 is a fastener.

In the outward perforated plate 31, the outer surface of the cylindrical inner wall 25 is circumferentially spaced at a pitch similar to or larger than that of the perforated plate 30 shown in FIG. The outer wall 24 is arranged in the vicinity of the outer wall 24. A plurality of through holes 31a for inserting all layers of the heat transfer tubes 27 arranged in the heat exchange chamber 26 into helical coils are formed in the outward porous plate 31 along the vertical direction and the radial direction. To be done.

As shown in FIG. 1, the inward facing porous plate 32 is arranged between the outward facing porous plates 31, and is integrally attached to the inner surface of the cylindrical outer wall 24 by a fastener 33 such as a bolt. . Then, in the inward porous plate 32, the inner portion thereof is arranged at a large radial interval with respect to the cylindrical inner wall 25, and the outer position of the heat transfer tubes 27 arranged in parallel in the radial direction. A plurality of through-holes 32a are formed in some of the layers along the vertical and radial directions.

As shown in FIG. 1, the fastener 33 has a cylindrical outer wall formed by, for example, screwing a bolt from a hole formed in the cylindrical outer wall 24 into a screw hole formed in the outer portion of the inward porous plate 32. 24 and the inward porous plate 32 are integrated.

A method of assembling the heat transfer tube 27 based on the support structure of the heat transfer tube for a steam generator having such a structure will be described below.

When the heat transfer tubes 27 are arranged in a plurality of layers, a plurality of outward perforated plates 31 are circumferentially spaced on the outer surface of the cylindrical inner wall 25 for the heat transfer tubes 27 which are located relatively inside. The heat transfer tube 27, which is vacant and attached by welding or the like, is passed through the through hole 31a of the outward porous plate 31 in order to finish it into a helical coil shape.

At that time, in the outer heat transfer tube 27,
The inward porous plate 32 is interposed between the outward porous plates 31, and the through holes 31a and the through holes 32a are alternately inserted to complete the helical coil shape.

After finishing the heat transfer tubes 27 for all layers into a helical coil shape, the outer portion of the inwardly directed porous plate 32 is integrally attached to the inner surface of the cylindrical outer wall 24 by the fasteners 33, so that FIG. Set as shown.

By inserting the heat transfer tubes 27 in this way, the layers located inside are supported in the same manner as in the example of FIG. 5, but the heat transfer tubes 27 located relatively outside are the outward facing porous plates. 31 and both through holes 31a, 32a of the inward porous plate 32
As a result, the supporting distance is reduced to about half as compared with the example of FIG. 5, and the supporting strength of the entire heat transfer tube 27 is improved.

[Other Embodiments] The following techniques can be adopted for the support structure of the heat transfer tube for a steam generator according to the present invention. a) The number of outward porous plates 31 and the number of inward porous plates 32 should be different. b) In that case, the pitch of the outward perforated plate 31 is partially narrowed and the arrangement of the inward perforated plate 32 is omitted. c) Disposing a plurality of inward porous plates 32 having different inward protruding lengths between the outward porous plates 31. d) Bending the outer part of the inward porous plate 32 and fixing it with the fastener 33.

[0027]

According to the support structure of the heat transfer tube for the steam generator of the present invention, the following effects can be obtained. (1) A plurality of outward perforated plates are arranged at intervals in the circumferential direction on the outer surface of the cylindrical inner wall, and a multi-layer helical coil-shaped heat transfer tube is inserted into the through hole of the outward perforated plate and between the outward perforated plates. Since the inward porous plate is arranged integrally with the inner surface of the cylindrical outer wall and the heat transfer tube is inserted into the through hole of the inward porous plate, the heat transfer tube is spread over the outward porous plate and the inward porous plate. By supporting it, the supporting strength can be improved, and in addition, the occurrence of fluid vibration can be suppressed. (2) By disposing the outward porous plate close to the cylindrical outer wall and arranging the inward porous plate in a state in which a space is provided in the radial direction with respect to the cylindrical inner wall, the assembling property of the heat transfer tube is not impaired. Especially, the support pitch of the heat transfer tube at the outer position is reduced,
It is possible to improve the support strength and suppress the occurrence of fluid vibration.

[Brief description of drawings]

FIG. 1 is a plan view of a main part showing an embodiment of a support structure for a heat transfer tube for a steam generator according to the present invention.

FIG. 2 is a front sectional view showing a conventional example of a light water cooling type nuclear reactor.

FIG. 3 is a front sectional view showing an example of a plan of a light water cooling type reactor.

FIG. 4 is a front sectional view showing a part of the steam generator of FIG. 3.

5 is a plan view of essential parts showing a supporting structure of the steam generator of FIG. 4. FIG.

[Explanation of symbols]

 1 Reactor Pressure Vessel 2 Core 3 Steam Generator 6 Primary Cooling Water Pump 21 Reactor Containment Vessel 21a Top Cover 24 Cylindrical Outer Wall 25 Cylindrical Inner Wall 26 Heat Exchange Chamber 27 Heat Transfer Tube 28 Water Supply Inlet 29 Steam Outlet 31 Outer Perforated Plate 31a Through hole 32 Inward porous plate 32a Through hole 33 Fastener G Gap P Boric acid water (reactor pool water) W Pool water

Claims (1)

[Claims] 1. A steam generator in which a heat exchange chamber is defined between a cylindrical outer wall and a cylindrical inner wall, and a helical coil-shaped heat transfer tube is arranged inside the heat exchange chamber. A plurality of outward perforated plates, which are arranged in a state of being close to the cylindrical outer wall in a circumferential direction on the outer surface of the inner wall, and in which heat transfer tubes are inserted into the through holes, Support for a heat transfer tube for a steam generator, characterized in that the heat transfer tube for a steam generator is provided with a plurality of inwardly directed perforated plates which are arranged integrally with each other and are radially spaced from a cylindrical inner wall and through which the heat transfer tubes are inserted. Structure.