JPH0763876A - Light water cooling reactor - Google Patents

Abstract

PURPOSE:To reduce leakage of primary cooling water fed to a steam generator, improve cooling efficiency and increase the detachable workability of a primary cooling water pump in a light water cooling reactor. CONSTITUTION:An outward connection tube 31 having an downward inclined outward opening face 31a is provided at the discharge opening of a primary cooling water pump 6, and an inward connection tube 32 having an inward opening face 32a jointed to the outward opening face 31a is set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light water cooling type nuclear reactor, and more particularly to improving the attachability / detachability of a primary cooling water pump when replacing a fuel assembly.

[0002]

2. Description of the Related Art FIG. 3 is a Japanese Patent Application Laid-Open No. H3-252593 (fuel assembly exchange device), Japanese Patent Application Laid-Open No. 3-252594 (fuel assembly exchange device), and Japanese Patent Application Laid-Open No. H3-25259.
5 shows an example of a light water cooled nuclear reactor described in Japanese Patent Publication No. 5 (fuel assembly exchange device).

In FIG. 3, 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 reactor core 2 rises, the raised primary cooling water is sent out to the inside of the poison tank 16 as shown by a broken 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. 3, 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. 4 shows another structural example (planned example) of the light water cooling type nuclear 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 core 2 from below as shown by the arrow in FIG. 4 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.

When performing the fuel assembly replacement work in these nuclear reactors, it is necessary to open the space above the core 2. At this time, FIG. 3 and FIG.
Of the reactor pressure vessel 1 shown in FIG.
Remove the top cover 21a of No. 1 to remove the primary cooling water pump 6
It involves the work of temporarily pulling out.

FIG. 5 shows an example of assembling the steam generator 3 and the primary cooling water pump 6 in consideration of the detachability of the primary cooling water pump 6. The discharge port of the primary cooling water pump 6 and the steam generator 3 are shown. Connection pipe 24 that connects these to the inlet of
Are arranged. This connecting pipe 24 is
The pair of joint flanges 24a are separated from each other, and a horizontal gap G of about 10 mm is set between the vertical flange surfaces of the pair of joint flanges 24a. The connection pipes 24 and the joint flanges 24a are arranged at four positions, for example, at intervals in the circumferential direction around the primary cooling water pump 6 in accordance with the number of installed steam generators 3 and the number of connected steam generators 3.

When the primary cooling water pump 6 is pulled out along with the replacement work of the fuel assembly, the upper lid 1a of the reactor pressure vessel 1 and the top cover 21a of the reactor containment vessel 21 are attached. The operation is performed by lifting and lifting the primary cooling water pump 6, taking care not to collide with the pair of joint flanges 24a based on the gap G.

[0013]

However, the connecting pipe 24
If the gap G exists in the gap G, the primary cooling water sent from the primary cooling water pump 6 to the steam generator 3 leaks from the gap G, which causes a phenomenon that the cooling efficiency of the primary cooling water is reduced. When the gap G is 10 mm, the efficiency decrease is estimated to be about 1%. On the other hand, the primary cooling water pump 6
The lifting work is carried out in water to reduce the radiation exposure, so it is difficult to set the lifting center accurately and to monitor the lifting situation, which tends to impair workability. The same problem occurs when the cooling water pump 6 is hung.

The present invention effectively solves the above-mentioned problems, and improves the cooling efficiency by reducing the leakage of the primary cooling water sent to the steam generator, and improves the workability of attaching and detaching the primary cooling water pump. Is intended.

[0015]

[Means for Solving the Problems] As a means for solving the above problems, a reactor pressure vessel is placed in the pool water of a reactor containment vessel in a submerged state, and the inside of the reactor pressure vessel is provided with an upper lid. In the case of a light water cooling reactor in which a primary cooling water pump that is suspended and forcibly circulates the primary cooling water, and a steam generator into which the primary cooling water is sent by the primary cooling water pump are arranged, The discharge port of the pump is provided with an outward connecting pipe that is integrally arranged along the radial direction and that has an outward opening surface that is inclined downward, and is integrally arranged along the radial direction at the inlet of the steam generator. At the same time, an inward connection pipe having an inward opening surface joined to the outward opening surface is provided.

[0016]

When the primary cooling water pump is assembled, the outward opening face of the outward connecting pipe and the inward opening face of the inward connecting pipe are brought into close proximity to each other, the gap between the joint portions is reduced, and the leakage of the primary cooling water is suppressed. . When the top cover of the reactor containment vessel is removed and the primary cooling water pump is lifted together with the upper lid of the reactor pressure vessel, both opening surfaces are separated in the vertical direction, so that they do not contact each other and interfere with each other. . When the outward opening surface of the outward connecting pipe and the inward opening surface of the inward connecting pipe are brought into close proximity by suspending the primary cooling water pump, both opening surfaces move in a slanting direction, resulting in a gap. In addition to the induction of a gradually reduced joining state,
Guidance toward the center is made by the contact of both opening surfaces.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a light water cooling type nuclear reactor according to the present invention will be described below with reference to FIGS. 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. 1 and 2, reference numeral 31 is an outward connecting pipe, 31a is an outward opening surface, 3
2 is an inward connection pipe, 32a is an inward opening surface.

As shown in FIG. 1, the outward connection pipe 31 is integrated with the discharge port of the primary cooling water pump 6 in a state of being horizontally connected in the radial direction and connected to the discharge port. Will be distributed. An outward opening surface 31a inclined downward is formed at the outer end of the outward connecting pipe 31.

As shown in FIG. 1, the inward connecting pipe 32 is integrally disposed at the inlet of the steam generator 3 horizontally in the radial direction and connected to the inlet. . At the inner end portion of the inward connection pipe 32, the outward opening surface 31
An inward opening surface 32a corresponding to a and parallel to this is formed in a state of being inclined upward.

In the light water cooling type nuclear reactor having such a structure, in the assembled state shown in FIG.
1 and the inward opening surface 3a of the inward connecting pipe 32
2a and 2a are brought into close proximity to each other so that the gap G at the joint portion is reduced to, for example, about 3 mm, or is set to zero, so that the opening faces 31a and 32a from the opening faces 31a and 32a during operation of the primary cooling water pump 6 can be reduced. Leakage of primary cooling water is suppressed.

When the primary cooling water pump 6 is pulled out at the time of exchanging the fuel assembly, the top cover 21a shown in FIG. 4 is removed and the primary cooling water pump 6 is lifted together with the upper lid 1a. However, when the primary cooling water pump 6 is lifted up, as shown in FIG.
By separating 1a and 32a in the vertical direction, a gap G
Is gradually increased, so both opening surfaces 31
It is less likely that a and 32a will contact each other and cause interference.

On the other hand, when the primary cooling water pump 6 is suspended, the outward connection pipe 31 is moved downward and the opening surfaces 3
Although the vertical gap between 1a and 32a is narrowed, the outward opening surface 31a that gradually descends moves in parallel with the inward opening surface 32a, so that the gap G becomes gradually smaller. At this time, since the outward opening surface 31a is displaced in the surface direction with respect to the inward opening surface 32a, in addition to the guidance to the joined state, the opening surfaces 31a and 32a are brought into contact with each other toward the central direction. Guidance is performed and the state of FIG. 2 is led to the state of FIG.

[0023]

The light water cooled nuclear reactor according to the present invention has the following effects. (1) A discharge port of the primary cooling water pump is provided with an outward connecting pipe having an outward opening surface inclined downward, and an inward opening surface having an inward opening surface joined to the outward opening surface at the inlet of the steam generator. Since the structure that the connecting pipe is provided is adopted, when assembling the primary cooling water pump, the gap between the opening faces of the outward connecting pipe and the inward connecting pipe is shifted in the surface direction, and the gap becomes small, so that steam is generated. It is possible to reduce the leakage of the primary cooling water sent to the vessel and improve the cooling efficiency. (2) Even when the gap between both opening surfaces is reduced,
A slight upward movement of the primary cooling water pump increases the gap between the opening surfaces, so that the workability of attaching and detaching the primary cooling water pump at the time of replacement of the fuel assembly can be improved. (3) By tilting both opening surfaces, the primary cooling water pump is guided to the center position when the opening surfaces come into contact with each other when the primary cooling water pump is hung down, and workability during assembly is improved. Can be improved.

[Brief description of drawings]

FIG. 1 is a front sectional view of essential parts showing an embodiment of a light water cooling-type nuclear reactor according to the present invention.

FIG. 2 is a front sectional view showing a vertically moving state of the primary cooling water pump of FIG.

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

FIG. 4 is a front cross-sectional view showing a plan example of a light water cooling reactor.

5 is a front cross-sectional view showing a connection state between the primary cooling water pump and the steam generator in the examples of FIGS. 3 and 4. FIG.

[Explanation of symbols]

 1 Reactor Pressure Vessel 1a Upper Lid 2 Core 3 Steam Generator 6 Primary Cooling Water Pump 17 Cooling Water Inlet 18 Water Pressure Operated Valve 21 Reactor Containment Vessel 21a Top Cover 31 Outer Connecting Pipe 31a Outward Opening Surface 32a Inward Connecting Pipe 32a Inward Opening Surface G Gap P Boric acid water (in-furnace pool water) W Pool water

Claims (1)

[Claims] 1. A primary reactor in which the reactor pressure vessel is submerged in pool water of the reactor containment vessel, and inside the reactor pressure vessel is suspended by an upper lid and forcibly circulates primary cooling water. A cooling water pump and a light water cooling type nuclear reactor in which a steam generator to which the primary cooling water is fed by the primary cooling water pump is arranged, wherein the discharge port of the primary cooling water pump is integrally formed along the radial direction. An outward connection pipe that is arranged and has an outward opening surface that is inclined downward is provided at the inlet of the steam generator integrally along the radial direction and joined to the outward opening surface. A light water cooling type nuclear reactor characterized by being provided with an inward connecting pipe having.