JPS61142392A - Vibration preventing device for internal pump - Google Patents

Abstract

PURPOSE:To prevent the occurrence of vibration, by providing a pair of key grooves which respectively have such a tapered surface as to allow slip between said key groove and plural key grooves, which are circumferentially formed in the inner surface of the lower part off a nozzle and the outer surface of a sleeve in a manner to be positioned facing each other. CONSTITUTION:A through-hole is bored in a lower end plate 11 of a reactor pressure vessel, a nozzle 11b is inserted thereinto, and is coupled to a sleeve 12a of a motor case 12. 3 or more key grooves 13, axially extended, are circumferentially formed in the inner surface of the lower end of the sleeve 11b, and key grooves 14, having a tapered surface, are formed in a position, allowing the key grooves to be respectively positioned facing the key grooves 13, in the outer surface of the end of the sleeve 12a. This, even if an axis is displaced due to a pressure and thermal deformation, prevents an increase in contact surface of the key, and enables prevention of production of vibration through relief of stress.

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.

[Technical backbone 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, as shown in FIG. It is generally known that a sleeve 2a of a case 2 is inserted and welded, and the lower end of the motor case 2 is connected to a base member 4 via a shock absorber 3 such as a snapper. In this type of vibration isolator, relative displacement occurs between the motor case 2 attached to the lower part 11 of the reactor pressure vessel and the foundation member 4 due to heat, internal pressure, etc. as the pressure vessel becomes high temperature. It is necessary to have a structure that allows this to escape. Also, shock absorber 3
Since the motor case 2 is required to have a function of restraining the motor case 2 against minute vibrations caused by the operation of the internal pump and large displacements caused by an earthquake, the structure becomes extremely complicated and large.

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.
Even if each of the internal pumps, which are normally installed in the lower mirror 1 of the reactor pressure vessel, were to be supported in two directions, the space occupied would be enormous. This not only results in an increase in the space at the bottom of the pressure vessel, but also has the problem of affecting the accessibility to heat exchangers, etc. located near the support.

(Objective of the Invention) The present invention has been made in consideration of the above points, and an object of the present invention is to improve safety, reliability, and economic efficiency by alleviating stress generated by equipment operation, earthquakes, etc. It is an object of the present invention to provide a vibration isolating device for an internal pump that can improve accessibility to equipment near the bottom of a pressure vessel and improve workability.

[Summary of the invention]

The present invention relates to a nozzle inserted into a through hole provided in a lower mirror of a reactor pressure vessel, and an internal pump which is inserted into the nozzle from its lower end side and whose upper end is connected to the upper end of the nozzle. a sleeve of the motor case, key grooves provided at least three circumferentially at approximately equal intervals so as to face each other on the inner surface of the lower part of the nozzle and the outer surface of the sleeve; This is a vibration isolator for an internal pump characterized by comprising a pair of key grooves each having a tapered surface as shown in FIG.

[Embodiments of the invention]

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

In FIG. 1, the reference numeral 11 partially indicates the lower mirror of the reactor pressure vessel, and the lower mirror 11 of the reactor pressure vessel is provided with 8 to 12 through holes. A nozzle 11b is inserted into the nozzle 11a.
As shown in FIG. 1, the sleeve 12a of the motor case 12 of the internal pump is loosely fitted into the inner pump 1b from the lower end thereof, and the upper end of the sleeve 12a of C and the nozzle 11
The −F end portion of b is integrally connected, for example, by welding or the like.

As shown in FIGS. 1 and 2, the inner surface of the lower end of the nozzle 11b is provided with first key grooves 13 extending in the axial direction at three or more locations in the circumferential direction (four locations in the figure). A second keyway 14 is provided on the outer surface of the lower end of the sleeve 12a at a position opposite to the first keyway 13.

A first key 15 and a second key 16 are inserted into the first key groove 13 and the second key groove 14 as a pair, respectively. The first key 15 and the second key 16 have tapered surfaces 15a and 16a formed on opposing surfaces, respectively, and these tapered surfaces 15a and 16a have slopes on which the keys 15 and 16 can slide against each other, The lower mirror 11 of the reactor pressure vessel and the motor case 12 have the same inclination angle due to the relative axial displacement and relative radial displacement.

Further, a bent portion 15b is formed on the lower surface of the first key 15 inserted into the first key groove 13 of the nozzle 11bllIll, and as shown in FIG. 3, the upper surface of the bent portion 15b is An elastic body such as a disc spring 17 is interposed between the two opposite to the lower end surface of the nozzle 11b, and the first key 15 and the nozzle 11b are connected by screwing the adjusting screw 18 from below the bent portion 15b toward the nozzle 11b. It is integrated.

Next, the operation of the above configuration will be explained.

If the lower end of the sleeve 12a is restrained by moving the first key 15 up and down the nozzle 11b using the adjusting screw 18 and eliminating the gap with the second key 16, it can be attached to the lower mirror 11 of the reactor pressure vessel. The attached nozzle 11b and the sleeve 12a of the pump case 12 undergo a relative axial displacement 2 and a relative radial displacement r at the lower end due to temperature difference, pressure difference, difference in material, shape, etc. compared to normal temperature and pressure.

Therefore, each relative displacement z in the restraint part at each position,
The slope of the sliding surface parallel to the relative displacement can be found from r.

Tapered surfaces 15a, 1 of first and second keys 15.16
By setting the inclination angle of the nozzle 11b to
and the tapered surface 15 due to the relative displacement of the lower end of the sleeve 12a.
a116a moves while maintaining a constant state of contact without relatively approaching or moving away. Therefore, even if the nozzle 11b1 sleeve 12a and its surroundings are deformed, a constant restraint state is always maintained by appropriately selecting the tapered surfaces 15a, 16a of the first and second keys 15, 16 according to the deformation. be able to.

〔Effect of the invention〕

As explained above, according to the present invention, a nuclear reactor pressure vessel,
Even if the axis of the key 15, 16 is shifted due to pressure or thermal deformation of the sleeve, the contact surface of the key 15, 16 will not expand, and the restraint state will remain constant. Therefore, displacement of piping, equipment, etc. due to equipment operation, earthquakes, etc. can be constantly restrained, and stress generated at the nozzle and sleeve connections can be alleviated, thereby improving earthquake resistance, reliability, and safety. Further, the restraint state can be arbitrarily adjusted by screwing the w4 node according to the usage state.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a first embodiment of the present invention, Fig. 2 is an enlarged sectional view taken along the line A-A 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 configuration diagram showing a conventional vibration isolating device for an internal pump. 11... Lower mirror of reactor pressure vessel 11a... Through hole 11b... Nozzle 12... Motor case 12a
...Sleeve 13...First keyway 14...Second keyway 15...First key 16...Second key 15a, 16a...Tapered surface 15b... Bent part 17... Belleville spring 18... Adjustment screw

Claims (3)

[Claims] (1) A nozzle inserted into a through hole provided in the lower mirror of the reactor pressure vessel, and a motor case for an internal pump that is inserted into this nozzle from its lower end and whose upper end is connected to the upper end of the nozzle. a sleeve, and at least three key grooves provided in the circumferential direction at approximately equal intervals, facing each other on the lower inner surface of the nozzle and the outer surface of the sleeve;
A vibration isolating device for an internal pump, comprising a pair of keyways each having a tapered surface that is inserted into the keyway and slidable relative to each other. (2) The key on the nozzle side is formed with a bent portion at the bottom, and an elastic body is interposed between the bent portion and the lower surface of the nozzle to adjust and fix it with an adjustment bolt. A vibration isolating device for an internal pump according to claim 1. (3) A patent claim characterized in that the tapered surfaces of the pair of keys are formed by matching inclination angles due to relative axial displacement and relative radial displacement between the lower mirror of the reactor pressure vessel and the motor case. A vibration isolator for an internal pump according to item 1.