JPS6123890A - Vibrationproof apparatus of internal pump - Google Patents

Abstract

PURPOSE:To simplify the structure of a vibrationproof apparatus by forming a key extending in the axial direction, in the peripheral direction onto one among the inner peripheral surface of the penetration hole of a pressure container and the outer peripheral surface of a motor case, in an internal pump. CONSTITUTION:A penetration hole 11a is drilled onto the lower mirror 11 of the pressure container of a nuclear reactor, and the motor case 12 of an internal pump is freely fitted from the lower edge side. Three or more keys 13 extending in the axial direction are integrally installed in the peripheral direction onto the inner peripheral surface at the lower edge of the penetration hole 11a, and a key way 14 corresponding to the key 13 is formed onto the motor case 12, and vibration can be prevented by the fitting between the key 13 and the key way 14. Therefore, structure can be simplified, and dimension can be reduced.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a vibration isolating device for an internal pump that is incorporated into a boiling water reactor pressure vessel and forcibly circulates coolant, and particularly relates to a vibration isolating device for an internal pump that is built into a boiling water reactor pressure vessel and forcibly circulates coolant. The present invention relates to a vibration isolating device for an internal pump that can be made smaller, more compact, and more reliable.

[Technical background of the invention and its problems]

The internal pump is a main component of the primary system that is built directly into the reactor pressure vessel, and also contains rotating parts.

Therefore, it is essential to alleviate the vibrations caused by the operation or the deformation caused by external forces such as earthquakes in order to improve the reliability and safety of the nuclear reactor.

Conventionally, as a vibration isolator for this internal pump, the upper end of the motor case 2 of the internal pump is inserted into a through hole 1a provided in the lower mirror 1 of the reactor pressure vessel, as shown in FIG. It is generally known that the lower end of the motor case 2 is connected to the base member 4 via a shock absorber 3 such as a snapper. In this type of vibration isolator, the reactor pressure vessel lower mirror 1
As the temperature of the pressure vessel increases, relative displacement occurs between the motor case 2 attached to the base member 4 and the base member 4 due to heat, internal pressure, etc., so it is necessary to have a structure to release this.

In addition, the shock absorber 3 must have the function of restraining the motor case 2 against minute vibrations caused by internal pump operation and large displacements caused by earthquakes, making the structure extremely complex and large. There are also drawbacks.

In addition, in order to deal with the arbitrariness of the direction of vibrations and earthquakes,
The motor case 2 is viewed from at least two directions in a horizontal section.
It is necessary to support the reactor pressure vessel lower mirror 1,
Even if support is provided in two directions for each of the internal pumps, which are usually installed in eight to twelve units, the amount of space occupied by the internal pumps is enormous, which not only results in an increase in the space at the bottom of the pressure vessel, but also increases the need for support. There is a problem in that it also affects the accessibility to nearby heat exchangers and the like.

[Purpose of the invention]

The present invention has been made in consideration of these points,
Provides a vibration isolator for internal pumps that can simplify and downsize the structure to improve reliability and economy, as well as improve accessibility and workability to equipment near the bottom of the pressure vessel. The purpose is to

[Summary of the invention]

As a means for achieving the above object, the present invention provides a key extending in the axial direction on at least one of the inner peripheral surface of the through hole provided in the lower mirror of the reactor pressure vessel or the outer peripheral surface of the motor case of the internal pump. are provided in a total of three or more locations in the circumferential direction, and at least one of the keys is provided with a keyway corresponding to the key, and the allowable displacement amount is adjusted by the gap in the circumferential direction between the key and the keyway. It is characterized by

[Embodiments of the invention]

The present invention will be explained below based on a first embodiment shown in FIGS. 1 to 3.

In the figure, 11 is a reactor pressure vessel lower mirror, and this reactor pressure vessel lower mirror 11 has 8 to 12 through holes 11.
A, that is, a pump nozzle is bored, and a motor case 12 of an internal pump is loosely fitted into this through hole 11a from the lower end side as shown in FIG. and the upper end of the through hole 11a are integrally connected, for example, by welding or the like.

1 and 2 on the inner circumferential surface of the lower end of the through hole 11a.
As shown in the figure, keys 13 extending in the axial direction are integrally provided at three or more locations in the circumferential direction (four locations in the figure), and are loosely fitted into the through hole 11a of the motor case 12. There is a key groove 1 corresponding to this key 13 in the part where the
4 are provided. The fit between the key 13 and the keyway 171 provides vibration isolation for the internal pump.

Note that a fitting tolerance is set for the gap between the contact surfaces between the key 13 and the keyway 14 according to the permissible amplitude, and the shape of the key 13 is determined according to load conditions such as earthquakes. There is.

Next, the operation of this embodiment will be explained with reference to FIG.

Since the inside of the motor case 12 is cooled,
The temperature difference between the reactor pressure vessel lower mirror 11 and the through hole 11a is as follows:
There is a possibility that the temperature can reach up to about 200°C at the rated time. Due to this temperature difference, the radial gap between the outer peripheral surface of the motor case 12 and the inner peripheral surface of the through hole 11a increases by ΔR.

This amount of displacement ΔR is ΔR-α・R・ΔT (1) However, α: Linear expansion coefficient R: Through-hole inner radius ΔT = Temperature difference. Assuming that the temperature difference ΔT is 200° C., the displacement amount ΔR is about 0.4#.

Therefore, in order to suppress the displacement tolerance to about 0.1 m+, for example, displacement restraint by contact between the key 13 and the keyway 14 in the radial direction cannot be expected to be effective.

Therefore, in this embodiment, as shown in FIG. 3, the displacement tolerance is adjusted by the circumferential gap X between the key 13 and the keyway 14.゛Here, if the change in the gap
W: Can be expressed by the width of the keyway. For example, if the width W of the keyway is assumed to be 1011n, the change opening ΔX will be approximately 0.01m, and by determining the fitting machining tolerance between the key 13 and the keyway 14 in consideration of this value, the pressure vessel Necessary displacement restraint is possible over the entire range from room temperature to high temperature.

Therefore, by replacing shock absorbing devices such as snappers that require complex functions with a simple key structure, the reliability and economical efficiency of the vibration isolator can be greatly improved.

In addition, the support that used to occupy a large space at the bottom of the pressure vessel is no longer required, which improves the accessibility and workability of equipment near the bottom of the pressure vessel, such as the internal pump heat exchanger, and frees up the space below the pressure vessel. Can be made more compact, reducing building construction costs and in-service inspection (ISI)
Cost reductions, including labor costs, can be expected.

In addition, all vibration isolators can be manufactured in a factory during the pressure vessel manufacturing process, eliminating the need for on-site assembly with other equipment and shortening the plant construction process.

4 and 5 show a second embodiment of the present invention, in which, contrary to the first embodiment, there is a key groove on the side of the through hole 11a.
4 is provided, and a key 13 is also provided on the motor case 12 side.

That is, as shown in FIG. 4, the internal pump motor case 12 is loosely fitted into 8 to 12 through holes 11a drilled in the reactor pressure vessel lower mirror 11 from the lower end side, and the motor The upper end of the case 12 and the through hole 1
The upper end portion of 1a is integrally connected, for example, by welding or the like.

4 and 5 on the inner peripheral surface of the lower end of the through hole 11a.
As shown in the figure, key grooves 14 extending in the axial direction are provided at three or more locations in the circumferential direction (four locations in the figure), and a portion of the motor case 12 that is loosely fitted into the through hole 11a is provided. A key 13 that fits into the keyway 14 is provided on the outer peripheral surface of the lower end. As in the previous embodiment, the vibration of the internal pump is damped by the fit between the key 13 and the keyway 14.

Therefore, even if the positions of the key 13 and the keyway 14 are reversed, the same effects as in the embodiment described above can be expected.

In both of the above embodiments, the keys 13 and the keyways 14 are provided at equal intervals in the circumferential direction to cope with the arbitrariness of the direction of vibrations and earthquakes, but they do not necessarily have to be at equal intervals. do not have. .

Further, in both of the above embodiments, the key 1 is attached only to either the inner circumferential surface of the through hole 11a or the outer circumferential surface of the motor case 12.
Although the explanation has been given on a case in which 3 are provided, for example, half of the number may be provided on both sides.

〔Effect of the invention〕

As explained above, the present invention provides a total of three or more locations in the axial direction on at least one of the inner peripheral surface of the through hole provided in the lower mirror of the reactor pressure vessel or the outer peripheral surface of the motor case of the internal pump. In addition to providing a key that extends to at least one of the keys, at least one of the keys is provided with a keyway corresponding to the key, and the allowable displacement is adjusted by the gap in the circumferential direction between the key and the keyway. Simplify and downsize the structure to improve reliability and economy.
At the same time, it is possible to improve the accessibility to equipment near the bottom of the pressure vessel and the workability.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a first embodiment of the present invention, Fig. 2 is an enlarged cross-sectional view taken along the line II-II in Fig. 1, and Fig. 3 is a method for adjusting the allowable displacement amount by the gap between the key and the keyway. FIG. 4 is a diagram corresponding to FIG. 1 showing the second embodiment of the present invention, FIG. 5 is an enlarged sectional view taken along the v-v line in FIG. 4, and FIG. FIG. 2 is a configuration diagram showing a vibration isolator. 11... Reactor pressure vessel lower mirror, 11a... Through hole,
12...Motor case, 13...Key, 14...
keyway. Applicant's agent Ino Mata 1. Heat-extinguishing 1.

Claims (1)

[Scope of Claims] 1. A through hole provided in a lower mirror of a reactor pressure vessel, and a motor case of an internal pump that is inserted into the through hole from the lower end side and whose upper end is connected to the upper end of the through hole. and,
At least one of the inner circumferential surface of the through hole or the outer circumferential surface of the motor case is provided with an axially extending key provided at a total of three or more places in the circumferential direction on one side, and at least one of the inner circumferential surface of the through hole or the outer circumferential surface of the motor case. and a keyway provided corresponding to the key on the other hand. 2. The vibration isolating device for an internal pump according to claim 1, characterized in that a key is provided on the outer circumferential surface of the motor case, and a keyway is provided on the inner circumferential surface of the through hole. 3. The vibration isolating device for an internal pump according to claim 1, characterized in that a key is provided on the inner circumferential surface of the through hole, and a key groove is provided on the outer circumferential surface of the motor case.