JPS5979891A - Pump for reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pump for a nuclear reactor, and more particularly, to a pop for a nuclear reactor that can improve seismic resistance by 10% and improve ease of installation.

[Technical background and problems of the invention]

Conventional cooling methods for BWR type light water reactors include a system in which 14 internal tubes are installed to circulate the coolant within the reactor, and the primary cooling system for the W Miko reactor is limited to the inside of the reactor.
ing.

In FIG. 1, which shows the cross-sectional structure of a conventional nuclear reactor pump used in such cases, a motor tacho is provided below the reactor vessel l, and a stator t and a rotor t are provided in a motor cutting ring 3. The drive shaft 6 is rotated by this. An impeller 7 is fixed to the tip of the shaft through the upper part of the drive shaft (:r), which passes through the wall of the reactor vessel L.The impeller 7 rotates inside the reactor, supplying the coolant to the defuzer G. The drive shaft 6 of C is supported by an upper journal $11, a lower journal bearing 10 and a thrust bearing //, and the diffuser g is It is fixed by a stretch tube 12 and a stretch tube nut /3 at the tip of the motor housing.A purge water pipe /g is provided on the inner surface of the motor housing 3.

However, in conventional pumps for elongated reactors with such a structure, the drive shaft 6 is supported only outside the reactor vessel.
Since there is no bearing that pivotally supports the directly lower part of the impeller 7, there is a risk that the impeller 7 will vibrate in the lateral direction due to deflection of the drive shaft B during an earthquake and come into contact with the diffuser G. In order to prevent the occurrence of such an accident, a method 11 is to provide a wear ring/l on the inner periphery of the diffuser g.

However, according to this method, even if there is no problem with the function of the pump in the event of an earthquake, the impeller 7 and the wear ring
There was a problem that the inside of the V reactor was contaminated due to abrasion as the V reactors slid in contact with each other. In addition, since there is no bearing to support the upper part of the drive shaft, in order to reduce the deflection of the shaft during ground Ti, it is necessary to increase the critical speed of the drive 11 by 11σ, so the shaft diameter should not be increased in the design. Special consideration of the above was necessary. Additionally, there is a stretch tube to secure the diffuser.

/2 and stretch tube nut /3, making it troublesome to assemble and adjust when installing the equipment. [Object of the Invention] Therefore, the purpose of the present invention is to prevent contact between the impeller and the diffuser in the event of an earthquake. It is an object of the present invention to provide a pump for a nuclear reactor that can prevent the above problems and easily fix a diffuser to a pump nozzle.

[Summary of the invention]

In order to achieve the above object, the present invention includes a drive shaft that is provided outside the reactor vessel and is driven by a single motor and is rotatably supported outside the reactor vessel, and this drive shaft penetrates the wall of the reactor vessel. In a nuclear reactor pump, the drive shaft is extended into the reactor vessel, and by rotating an impeller provided at the tip of the drive shaft, coolant is discharged and circulated into the reactor vessel through a diffuser. The tip is rotatably supported by a hydrostatic bearing that utilizes purge water, making it possible to reduce deflection of the drive shaft during earthquakes. Furthermore, the installation of the equipment can be improved by providing a hole that extends into the furnace vessel and fits into the tip of the motor housing.

[Embodiments of the invention]

Below, a first embodiment of a nuclear reactor pump according to the present invention will be described.
2 through 3, in which the same parts as in the figures are denoted by the same reference numerals, will be explained with reference to the figures.

In Fig. 2, a vertical motor tacho is provided immediately below the outside of the reactor vessel l, and a stator ≠ provided in the housing 3 of this motor λ and a rotor j are connected, and a drive shaft protrudes upward from the motor J. t is rotationally driven. The motor housing 3 extends vertically upward from the top of the motor 2, enclosing the drive shaft 6, and extends concentrically into the reactor vessel. is fixed. As the drive shaft B rotates, the impeller 7 rotates within the furnace, energizes the coolant, and circulates the coolant in the furnace through the defuzer G. There is a step 3a on the inner peripheral surface of the tip of the motor housing 3 that extends into the furnace.
A hydrostatic bearing 16 for pivotally supporting the end portion of the drive shaft 6 is provided on this step 'm3a. As shown in an enlarged view in FIG. 3, this static pressure bearing/A has an annular pressure holding slot 17 on its inner circumferential surface, and this slot 7 is accessed from the outside of the motor to the inner periphery of the motor tassel 3. Noku placed on the surface
The end of the purge water pipe /g is opened to introduce high-pressure purge water into the slit /7, so that the fluid pressure of the purge water can hold the drive shaft 6 in a non-contact state with the hydrostatic bearing /A. ing.

Therefore, the drive shaft 6 is a conventional upper journal wheel.
In addition to the 1 bridge and the lower journal bearing, the lower portion of the upper impeller 70 surface is equipped with a hydrostatic bearing/A, totaling 3
Since it is supported at a point, it is possible to increase the critical speed of the drive shaft without increasing the shaft diameter. Therefore, the vibration of the drive shaft during an earthquake is significantly suppressed, preventing contact between the impeller 7 and the differential wear ring, which greatly improves the vibration distribution and reliability of the pump. Be able to do that.

Further, as shown in FIGS. 3 and V, a protruding stopper/9 is provided on the outer peripheral surface of the upper end of the motor housing 3 in order to fix the diffuser g, and the inner diameter of the lower end of the diffuser g is fixed to the motor It is formed to be slightly thicker than the outer diameter of the upper end of the Ujifugu, and 20 L-shaped grooves are provided on the inner circumferential surface of the lower end of the diffuser for fitting with the stopper /q. Therefore, by fitting the stopper /9 into this L-shaped groove 20 and rotating the diffuser t111, both can be easily locked. The arrows in Figure V indicate the direction of the reaction force that the diffuser receives.1 Therefore, when installing the diffuser, it is necessary to use a stretch tube and stretch cheap nut as shown in Figure 1. Insert the diffuser from the second part of the reactor vessel instead of 1. , by rotating in the direction of the reaction force.

-[-Effects of the Invention] The above theory shows that the present invention has the effect of the invention.
In other words, the drive shaft is supported directly below the impeller by a hydrostatic bearing that uses purge water, which prevents vibration of the drives 4 and 11 during earthquakes and prevents contact between the impeller and the detour ring. This can greatly improve the earthquake resistance and reliability of the pump.

Also, without using stretch tubes and nuts,
It is extremely easy to assemble and remove the power that can be directly attached to the motor housing, and at the manufacturing stage, assembly and adjustment can be carried out in a pre-assembled state before the furnace vessel is inspected. This makes it possible to improve and ensure installation accuracy.

[Brief explanation of the drawing]

1] is a longitudinal sectional view showing a conventional nuclear reactor pump, Fig. 2 is a longitudinal sectional view showing an embodiment of the nuclear reactor pump according to the present invention, and Fig. 3 is a longitudinal sectional view showing the neck 1 in Fig. 2. Pressure+i), 1 is an enlarged detailed view showing the vicinity of the receiving part, and the second figure is a directional arrow v1 view of 1-A-, which shows the fitting part of the diffuser in FIG. 3... Motor nozzle, t... Drive shaft, 7...
・Impeller, g... Diffuser, /I/, -... Wearing, /6... Throttle pressure bearing, /7... Slit,
/q...Stotsunoku1. ! 0...L-shaped groove.

Claims (1)

[Claims] 1. A drive shaft driven by a motor ΔI provided outside the reactor vessel is rotatably supported outside the reactor vessel, and this drive shaft is inserted through the wall of the reactor vessel to In a nuclear reactor pot which extends into the reactor vessel and discharges coolant into the reactor vessel through a diffuser and circulates it by rotating an impeller having an IL-shaft at the tip of the drive shaft, the tip of the drive shaft is A nuclear reactor pump characterized by being rotatably supported by a hydrostatic bearing. 2. The pump according to claim 1, wherein the fluid used in the hydrostatic bearing is purge water. 36. A patent claim characterized in that the housing of the motor unit is extended into the reactor vessel so as to enclose the drive shaft, and the Teifusa is removably locked to the tip of the extended motor cousing. The pump according to item 1 in the range of