JPH0361917B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a vibration isolation mechanism for an internal pump attachment part provided at the lower part of a pump attachment nozzle of a new type of boiling water nuclear reactor.
This invention relates to a vibration isolation mechanism that provides a mechanism that can prevent not only thermal deformation but also vibration between the heat insulating sleeve of the pump mounting nozzle and the pump casing of the internal pump.

[Background of the invention]

As is well known, boiling water reactors are widely adopted and operated in nuclear power plants, but various improvements have been made and so-called A-BWR new boiling water reactor type nuclear plants are being adopted. I'm getting used to it.

As shown in Fig. 1, a set number of internal pumps 2, 2, ... are installed around the bottom of the pressure vessel 1 of the A-BWR reactor to circulate cooling water for cooling. has been done.

As shown in detail in FIG. 2, the internal pump has a pump shaft 6 rotating in the lower part of the pump casing 5 attached to the heat insulating sleeve 4 of the pump mounting nozzle 3 of the pressure vessel 1. A submersible motor 7 is provided, and a pump impeller 8 and a differential user 9 are provided inside the upper pressure vessel 1.
is provided as the pump hydraulic power section.

The internal pump 2 is mounted to the pressure vessel 1 at the bottom of the pressure vessel 1 in an asymmetrical manner with respect to the radial direction for reasons of design.

Therefore, when the temperature of the nuclear reactor increases as the A-BWR operates, the temperature of the pressure vessel 1 also increases, and therefore the pump casing 5 also undergoes thermal expansion and thermal deformation.

Incidentally, since the pump casing 5 is fixed to the pressure vessel 1 by welding, the pump casing 5 is disposed asymmetrically in the radial direction of the bottom of the pressure vessel 1 as described above, thereby preventing thermal deformation of the pump casing 5. Naturally, if the pump shaft 1 is kept in a restrained state, a large thermal stress is generated in the bottom part of the pump shaft 1.

To deal with this, the conventional A-BWR employs a pump attachment nozzle 3 of the pressure vessel 1 that is of a thermal stress relaxation type and has excellent thermal deformation followability.

However, while pump-mounted nozzles with excellent followability are excellent at restraining thermal deformation, they lack rigidity and are less effective against vibrations.In particular, they have little resistance against low-frequency vibrations, making them vulnerable to plant vibrations. There was a drawback.

Further, the pump casing 5 is integrally provided with an annular protrusion in order to improve installation accuracy when attaching to the pump mounting nozzle 3. However, as mentioned above, the annular protrusion is not installed for the purpose of vibration isolation, so the contact between the annular protrusion and the heat insulating sleeve 4 is It is unavoidable that minute gaps are formed between the two, and moreover, they are non-uniform, and therefore the vibration-proofing effect is not necessarily sufficient.

In this way, because the vibration prevention function is not sufficient or because of the anisotropy, the durability of the internal pump 2 may not be as designed, or leakage may occur. There was a problem that may cause serious problems.

[Purpose of the invention]

The object of the present invention is to
The problem of the vibration isolation mechanism of the pump mounting nozzle for the internal pump installed in the lower part of the BWR pressure vessel was set as a technical issue to be solved. It is an object of the present invention to provide an excellent vibration isolation mechanism for a boiling water reactor pressure vessel that is fully functional and beneficial to the field of pump application in the nuclear power industry.

[Summary of the invention]

The summary of the present invention, which is based on the above-mentioned claims in accordance with the above-mentioned object, is to solve the above-mentioned problems by providing a heat-insulating sleeve for a pump mounting nozzle of an A-BWR pressure vessel and an internal pump provided inside the heat-insulating sleeve. A convex part and a concave part are provided in the radial direction on one and the other of the pump mounting nozzles to form a fitting part, and a heat insulating material is interposed in at least a part of the fitting part to prevent the pressure vessel from rising in temperature during reactor operation. Then, the gap between the convex part and the concave part becomes gradually narrower, the pump casing and the heat insulating sleeve become integrated through the heat insulating material, the natural frequency increases, and it is prevented from vibrating due to low frequency vibration, etc. The vibration isolation function is now fully achieved, and the radial expansion and contraction of the pump casing is sufficiently tolerated.In addition, due to the insulation, the heat input from the pressure vessel is reduced to A-BWR.
Technical measures have been taken to ensure that the circulation of cooling water is not hindered.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described below based on the drawings from FIG. 3 onwards.

Note that the same parts as in FIGS. 1 and 2 will be described using the same reference numerals.

The aspect of the embodiment shown in FIG. 3 is substantially an enlarged view of the part shown in FIG. 2, and a set number of internal pumps 2, 2, . The pump casing 5
is integrally provided via welding 10 to the upper part of a flexible type heat insulating sleeve 4 that can easily follow thermal deformation of the pressure vessel 1, and the heat insulating sleeve 4
It is interposed with a set gap 11 in between.

The gap 11 forms an insulating air layer that evens out the distribution of heat in the reactor.

Further, between the two, an annular projection 12 is formed on the pump casing 5 side in the form of a ring to oppose the heat insulating sleeve 4 and improve installation accuracy.

In this invention, as shown in FIG. 4 and below, on one side of the heat insulating sleeve 4, four convex portions 13 are provided at intervals of 90 degrees in the circumferential direction over almost the entire axial length of the sleeve. 13 are integrally formed, and on the other hand, long notches 14, 14, 14 as recesses corresponding to each of the spills 13 are recessed in the axial direction on the outer periphery of the pump casing 5.

Glass wool 15 as a heat insulating material is attached to the three inner front surfaces of the notch 14 over the entire length in the longitudinal direction using an appropriate adhesive or the like.

In the illustrated embodiment, the notch 14 is formed in the shape of a bulge formed on the outer peripheral surface of the pump casing 5, but it may be formed in the shape of a circumferential surface.

The spill 13 and the notch 14 form a fitting portion 16.

In the above configuration, when the temperature of the A-BWR reactor is low, the pump casing 5 and the heat insulating sleeve 4 are in the state shown in FIG.
The gap 11 is set wide.

When the nuclear reactor is actively operated and the temperature rises, the heat insulating sleeve 4 expands due to the heat, but its inner diameter is reduced by the heat and the spill comes inside.

However, one reason is that the pump casing 5 is cooled and does not expand because cooling water flows through its inside, and two, the glass wool 15 is attached to the inner surface of the notch 14. Because of this, the heat from the convex portion 13 does not enter and the two do not expand together. Therefore, only the spill 13 enters the notch 14 and gradually the gap between the fitting portions 16 becomes smaller as shown in FIG. The heat insulating sleeve 4 and the pump casing 5 are integrated and rigidly connected via the heat insulating material 15.

Even in the integrated connected state, the temperature of the pump casing 5 does not rise due to gap circulation and heat insulation by the heat insulating material 15.

Therefore, the thermal expansion of the fitting part 16 does not become so large, so that the pump attachment nozzle 3 is kept sufficiently flexible.

On the other hand, even if vibrations, particularly low-frequency vibrations, occur in a nuclear power plant, the pump casing 5 is
Vibration can be sufficiently prevented by connecting the heat insulating sleeve 4 to the heat insulating sleeve 4 via the heat insulating sleeve 4.

Since extreme thermal expansion of the pump casing 5 does not occur, the generation of thermal stress on the pressure vessel 1 is suppressed, thermal deformation is not restrained, and the stress is sufficiently relaxed.

It goes without saying that the embodiments of this invention are not limited to the above-described embodiments; for example, various embodiments can be adopted, such as reversing the protrusions and recesses with respect to the heat insulating sleeve and pump casing. .

According to the above embodiment, by providing a vibration isolation mechanism in the pump installation nozzle of the internal pump to the bottom of the pressure vessel of the A-BWR, even if the temperature of the reactor rises, thermal deformation of the internal pump can be avoided. An excellent effect is achieved in that the anti-vibration function can be realized without any restrictions.

Therefore, there is an excellent effect of improving the seismic resistance and vibration damping properties of the internal pump even while the A-BWR is in operation.

Moreover, not only the vibration-proofing function is improved, but even if thermal deformation occurs as in the conventional case, the thermal stress can be dispersed and suppressed to a low level.

By providing a convex portion on one side of the heat insulating sleeve and the pump casing of the pump mounting nozzle of the pressure vessel and a concave portion on the other side in the radial direction, vibration is not only prevented in all directions, but also thermal expansion and contraction are completely prevented. It has the excellent effect of being absorbed by the pump and preventing twisting of the pump mounting nozzle.

In particular, there is no movement of the center of the pump casing with respect to the heat insulating sleeve, and the excellent effect is that expansion and contraction of the long pump shaft in the vertical direction can be tolerated.

In this way, it is possible to reliably provide the effect of adding a vibration damping function while sufficiently maintaining the function of following thermal deformation as in the conventional case.

〔Effect of the invention〕

In the present invention, the heat insulating sleeve of the pump mounting nozzle and the pump casing fitted inside the sleeve are radially matched through a fitting part in which one side is a convex part and the other is a concave part, and the heat insulating sleeve of the pump mounting nozzle is radially connected to the pump casing. As the inner diameter of the heat insulating sleeve at the fitting portion decreases, the heat insulating sleeve and the pump casing fitted into the sleeve gradually become integrated through the heat insulating material at the fitting portion where one side is a convex portion and the other is a concave portion. At the same time, the heat insulating material interposed in the joint prevents heat input from the pump mounting nozzle side to the pump casing side, and the pump casing side The coupling of the fitting part due to thermal expansion of the fitting part does not become excessive, the flexibility of the pump mounting nozzle is maintained, the occurrence of thermal deformation stress is alleviated, and the effect is that it reliably provides vibration isolation and thermal deformation follow-up function. can get.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the arrangement of the internal pump in the A-BWR pressure vessel, Figure 2 is a cross-sectional view of the installation of the internal pump in the pressure vessel, and Figure 3
The following figures are explanatory diagrams of one embodiment of the present invention: FIG. 3 is a sectional view of the connection between the heat insulating sleeve and the pump mounting nozzle, FIG. 4 is a side view of the fitting part, and FIG. 6 and 7 are plan views of the fitting portion, and are respectively enlarged sectional views of the portion in FIG. 5 at normal temperature and high temperature. 1...Pressure vessel, 2...Internal pump,
3...Pump mounting nozzle, 4...Insulation sleeve,
5...Pump casing, 13...Convex portion (spill), 14...Concave portion (notch), 15...Insulating material.

Claims (1)

[Scope of Claims] 1. In a vibration isolation mechanism interposed between a pump casing of an internal pump provided at the lower part of a pressure vessel of a boiling water reactor and a heat insulating sleeve of a mounting nozzle of the internal pump, The heat insulating sleeve of the pump mounting nozzle and the pump casing fitted into the sleeve are connected radially at multiple locations in the circumferential direction through fitting portions, one of which is a convex portion and the other of which is a recess, and the fitting portion A vibration isolation mechanism for a boiling water reactor pressure vessel characterized by having a heat insulating material interposed therein. 2. Claim 1, wherein the convex portion and the concave portion are formed to have substantially the entire length in the vertical direction.
Vibration isolation mechanism for a boiling water reactor pressure vessel as described in . 3. The vibration isolation mechanism for a boiling water reactor pressure vessel according to claim 1, wherein the convex portion and the concave portion are formed in a portion in the vertical direction. 4. The vibration isolation mechanism for a boiling water reactor pressure vessel according to claim 1, wherein the heat insulating material is provided throughout the fitting portion. 5. The vibration isolation mechanism for a boiling water reactor pressure vessel according to claim 1, wherein the heat insulating material is glass wool.