JPS60205290A - Cooling system of recirculating pump in nuclear 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] Does this invention provide recirculation within a nuclear reactor? related to the cooling system of the pump.

[Technical background of the invention and its problems]

FIG. 1 is an explanatory diagram showing a conventional cooling system for a recirculation pump in a nuclear reactor.

Generally, the reactor recirculation bond 2 installed at the lower part of the reactor pressure vessel 1 needs to cool its motor section 3 and the like to ensure normal operation.

The reactor recirculation pump 2 is cooled not only by the primary cooling water of the secondary cooling system 4 but also by the purge water system 5.

The purge water system 5 boosts the pressure of water replenished from the outside with a purge system pressure pump 9, and re-injects it into the reactor from a purge water inlet nozzle 13 as purge water with a pressure higher than that of the coolant in the reactor pressure vessel 1. It is supplied into the pump casing 15 of the circulation pump 2. The purge water supplied into the pump casing 15 flows through the pump casing 15 and the shaft 1.
7 and flows out into the reactor pressure vessel 1. As a result, high-temperature coolant (approximately 3000 ml) inside the reactor pressure vessel 1
is prevented from flowing into the pump casing 15 from between the pump casing 15 and the shaft 17, and the motor section 3 and the like inside the pump casing 15 can be maintained at a low temperature.

Further, a seal water system 18 is provided in parallel to the purge water system 5. This seal water system 18 is pressurized by an external water/metal seal system pressure pump 19 to produce seal water, and this seal water is supplied into the pump casing 15 from a seal water inlet nozzle 21 . Inside the reactor Fi) Circulation d? During maintenance and inspection of the pump, the supply of ♀-d water from the purge water system 5 is cut off, and the seal water system 18 is activated. The supply of seal water from the seal water system 18 prevents the coolant from flowing into the motor section 3 side.

Note that the reference numeral C, 25 is a check valve, and the reference numeral 27 is a heat exchanger of the primary cooling system 4.

However, the reactor pressure vessel 1 normally requires 12 reactor recirculation pumps 2, and each reactor recirculation pump 2 has a primary cooling system 4°, a groove system 5 and a seal. Since the system 18 is provided, when the reactor recirculation pump 2 is operating, the flow rate, temperature, pressure, etc. of the fluid flowing through each group must be monitored every 4.5 degrees 18. Therefore, there is a problem that the operation control of the in-reactor recirculation pump 2 becomes complicated.

Further, there is a drawback that the installation space for the piping of each group 4, 5, 18 becomes large, and maintenance and inspection work for the in-reactor recirculation pump 2 becomes complicated.

[Purpose of the invention]

This invention is a book made in consideration of the above facts,
This invention relates to a cooling system for a recirculation pump in a nuclear reactor that can simplify operation control and maintenance and inspection work.

[Summary of the invention]

In order to achieve the above object, the cooling system for an in-reactor recirculation pump according to the present invention uses an impeller housed inside the reactor pressure vessel to coolant f inside the reactor pressure vessel:
When applied to an in-reactor recirculation pump that performs forced circulation, a primary cooling system pressurizing pump is installed in the primary cooling system that supplies primary cooling water to the in-reactor recirculation pump. is set at a higher pressure than the coolant, and a water supply pipe is connected to the secondary system pressurizing pump, and primary cooling water is appropriately supplied from this water supply pipe. This system allows primary cooling water to flow into the reactor pressure vessel from between the shaft and casing of the reactor recirculation pump.

[Embodiments of the invention]

Hereinafter, the implementation of this invention will be explained based on the details.

Figures 2j and 3 show the inside of the nuclear reactor according to this invention, lJ
+ It is an explanatory view showing one example of the cooling system of Donzo.

As shown in FIG. 2, inside the reactor pressure vessel 31,
A reactor core 33 and a coolant are accommodated therein. In the lower part of this reactor pressure vessel 31, several Mt, usually 12 in-reactor recirculation pumps 37 are installed. The reactor recirculation pump 37 guides the coolant to the reactor core 33, where it is heated and becomes a two-phase flow of steam and water.

This two-phase flow is separated into steam and saturated water by a steam/water separator 39, and the steam is guided to a steam dryer 41 disposed above the steam/water separator 39 and dried. The steam is led from the steam outlet nozzle 43 to the main steam pipe.

In addition, the saturated water Vi separated by the steam separator 39 flows down inside the reactor pressure equalizer 31 and is again forcedly circulated to the reactor core by the reactor recirculation pump 37.

FIG. 3 shows an in-reactor recirculation pump 37 that forcibly circulates the coolant 35 in this manner.

Each pump casing 45 of the plurality of in-reactor recirculation pumps 37 is vertically installed in the lower part of the reactor pressure vessel 31 . A lower large diameter portion of the pump casing 45 faces the outside of the reactor pressure vessel 31, and a stator 47 is fixedly disposed inside this lower large diameter portion. On the other hand, a rotor shaft 49 is housed within the pump casing 45 .

The rotor shaft 49Fi is rotatably supported by the upper radial ring 46 and the lower radial bearing 48. The rotor shaft 49 is formed so that its upper end reaches into the reactor pressure vessel 31, and the rotor 51 is positioned opposite the stator 470.
will be placed. These stator 47 and rotor 5]K
Thus, the motor part of the reactor recirculation bomb f37 is formed.

A pump impeller 5 is also provided at the upper end of the rotor shaft 49.
3 is installed protrudingly. The pump impeller 531C faces the outer cylinder 57 of the differential user 55, and the inner cylinder 59 is connected to the outer cylinder 57. The inner cylinder 59 is the reactor pressure vessel 31'
is fixed on the nozzle pump 61 of. These pump impeller and diffuser group form the pump section of the reactor recirculation pump 37.

On the other hand, a thrust disk 63 is fixed to the lower end of the rotor shaft 49. This thrust disk 63 is rotatably supported by the thrust bearing 6 and the pump casing 45. Further, a bottom plate 67 is fixed to the lower end of the pump casing 45, and the bottom plate 67 forms a closed channel ω surrounding the thrust disk 53.

Further, the pump casing 45 is provided with a cooling water inflow lower 1 communicating with the closed chamber at its lower part, and a cooling water outflow lower 3 is formed approximately at the center in the axial direction. A primary cooling system piping 77 of a secondary cooling system 75 is connected to the cooling water inflow lower 1 and the cooling water outflow lower 3 .

A heat exchanger 79 is installed in the primary cooling system piping 77 .

-The primary cooling water flowing through the secondary cooling system piping 77 is connected to the heat exchanger 79
Inside, the secondary cooling water flowing through the secondary cooling system piping 81 cools the temperature. Further, a locking adjustment valve for temperature adjustment is provided on the upstream side of the heat exchanger 79 in the secondary cooling system piping 77, and this flow rate adjustment valve section controls the control of the primary cooling water flowing into the heat exchanger 79. The key is adjusted.

The temperature of the primary cooling water is set to maintain the motor parts 47 and 51 of the reactor recirculation pump 37 at about 60C or less, but the temperature is controlled by the heat exchanger 79 between the temperature control flow rate regulating valves. Adjusting the flow rate of the primary cooling water flowing into the
It is controlled by adjusting the flow rate of the secondary cooling water in the secondary cooling system piping 81.

Further, on the downstream side of the heat exchanger 79 of the secondary cooling system piping 77,
- A ceiling cooling system pressure pump 85 is provided. By this secondary cooling system pressurizing pump 85, the secondary cooling water is pressurized to a pressure slightly higher than the coolant pressure (approximately 70.7 mm) in the reactor pressure vessel 31, and is introduced into the closed chamber 69. It will be destroyed.

A water supply pipe 87 that supplies primary cooling water from the outside is connected to the suction side of the primary cooling system pressurizing pump blade.

This water supply pipe 87 is connected to a replenishment flow rate adjustment valve 89 from that side of the secondary cooling system pressurizing pump. A check valve 91 is provided in the fourth order. The replenishment flow rate adjustment valve 89 is connected to the secondary cooling system distribution "ff".
The make-up water υii;

By closing the temperature circular v1j 1llIIA adjustment F83 and the supply flow rate adjustment valve 89 and the check valve 91, -
Even if the water cooling system pressure pump 85 should stop, the cooling water in the reactor pressure vessel 31 is prevented from flowing out, and the water level in the reactor pressure vessel 31 is maintained at a predetermined level.

Although not shown in FIG. 3, the pump casing 15
A seal water inlet nozzle is provided at the upper part of the cooling water outflow lower 3. A seal water system is connected to this seal water inlet nozzle, and seal water is supplied to the seal water inlet nozzle during maintenance and inspection of the in-reactor recirculation pump to enable the seal mechanism inside the pump casing 15. Due to the operation of this sealing mechanism, the pump casing 15 is
This prevents the coolant from flowing inside, and allows maintenance and inspection of the motor sections 47 and 51 by removing the bottom plate 67.

Next, the effect will be explained.

When the primary cooling system pressurizing pump operates, the secondary cooling water is pressurized and flows from the cooling water inlet lower 1 into the closed chamber/ω. The primary cooling water that has flowed into the sealed channels 69 is guided to the thrust bearing field and the lower radial bearing 45 by the rotation of the thrust disk 630.
These 65,451- are cooled, and further the motor section (stator 47, rotor 51) is cooled.

During reactor operation, the inside of the reactor pressure vessel 31 reaches a high temperature of about 300 C, and this heat is transmitted to the motor sections 47 and 51 via the pump casing 45 and the rotor shaft 49, as described above. .51 is cooled by primary cooling water and maintained below about 60C.

The primary cooling water that has cooled the motor sections 47 and 51'i further cools the upper radial bearing 46, and then most of the cooling water is transferred from the cooling water outflow lower 3 to the temperature FA saving flow M'al'J regulating valve. Reach Seki. - The flow rate of the secondary cooling water is adjusted by the temperature control I5i+ and the θ4 regulating valve 83, and is then passed through the heat exchanger 79 to heat the Tanabata sections 47 and 51 to about 60C.
Cool to below (1., heated to AM. Then -
The secondary cooling water reaches the primary cooling system piping 114.

On the other hand, the pressure of a portion of the primary cooling water that cooled the upper radial bearing 46 is slightly higher than the pressure of the coolant 5 in the reactor pressure vessel 31, so the pressure is slightly higher than that of the coolant 5 in the reactor pressure vessel 31. Climb up the gap 93A. The primary cooling water in the gap 93A rises even further, and flows between the inner cylinder 59 of the differential user 55 and the rotor shaft 49! i! 93B, between the outer cylinder 57 and the pump impeller field [93Ct--quietly flows into the reactor pressure vessel 31. As a result, the high temperature (approximately 300 C) coolant flows into the gap 93.
C, 93B, 93All-approaching pump casing 4
5 is prevented from entering the motor parts 47 and 51.
is maintained at a low temperature (approximately 60C or less).

- The flow rate flowing into the primary cooling system piping 771 decreases due to the secondary cooling water flowing into the reactor pressure vessel 31, but this -
Due to the operation of the flowmeter installed in the secondary cooling system piping 77 and the replenishment flow rate adjustment valve 89, the amount equivalent to the decrease is reduced to the water supply piping 87.
is supplied to the primary cooling system piping pump 85. Therefore, even when the water flows out into the reactor pressure vessel 31, the flow of the primary cooling system piping through the secondary cooling system piping 77 is always constant.

According to the above embodiment, the secondary cooling water is pressurized to a pressure slightly higher than that of the coolant in the primary cooling system pressurized ponzo system and is supplied into the pump casing 45, and this high-pressure secondary cooling water is pumped into the gap. 93A, B, and C into the reactor pressure vessel 31, there is no need for a conventional purge water system. Therefore, in the operation control of the cooling system of the in-reactor recirculation pump 37, the flow rate, temperature,
It is sufficient to monitor the pressure, etc., and the operation control in the cooling system of the reactor circulation pump 37 can be simplified.

1. Since the purge water system becomes unnecessary and the purge water system piping is removed, the space around the lower part of the reactor pressure vessel 31 can be expanded. Therefore, maintenance and inspection work on the in-reactor circulation pump 37 can be easily performed.

Furthermore, since a purge water system is not required, equipment costs can be reduced.

However, in this embodiment, since there is no security in forming a purge water inlet nozzle, one of the reactor recirculation bolts 37 is
1!8! The manufacturing process can be simplified and manufacturing costs can be reduced.

〔Effect of the invention〕

As described above, according to the cooling system for the in-reactor recirculation pump according to the present invention, the primary system pressure pump is disposed in the primary cooling system that supplies primary cooling water to the in-reactor recirculation pump, - Because the secondary cooling water is at a higher pressure than the coolant in the reactor pressure vessel, and the primary cooling water is appropriately supplied from the water supply pipe connected to the secondary cooling system pressurizing pump,
The purge water system was removed, and the primary cooling water was made to flow into the reactor pressure vessel from between the reactor interior 44 + circulation pump shaft and casing. As a result, monitoring of the cooling system of the reactor recirculation pump during reactor operation is sufficient by monitoring only the primary cooling system, and the space at the bottom of the reactor pressure vessel can be occupied by all personnel. This has the effect that the operation control and maintenance and inspection work in the cooling system of the internal recirculation pump can be completely simplified.

[Brief explanation of drawings]

Fig. 1 is a piping diagram showing a conventional cooling system for an in-reactor recirculation pump, and Fig. 2 shows an in-reactor noble circulation system to which an embodiment of the in-reactor recirculation pump cooling system according to the present invention is applied. FIG. 3 is an enlarged duct diagram showing this embodiment. 31... Reactor pressure vessel, 37... Reactor recirculation ponzo, 47... Stator, 49... Rotor shaft, 51... Rotor, 5:3... Bon twin bellows,
75... - secondary cooling system, 79... heat 5i'' exchanger, 83
... Temperature 1114 Node flow '11 regulating valve, connection...-
Secondary cooling system pressure pump, 87... Water supply piping, 89...
Replenishment flow rate adjustment valve. Representative Patent Attorney Noriyuki Chika (#1 person) Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. This in-reactor recirculation pump is applied to an in-reactor recirculation pump that forcibly circulates the coolant inside the pressure vessel by an impeller housed inside the reactor pressure vessel. A primary system pressure pump is installed in the primary cooling system that supplies primary cooling water to the upper 8-pin system to make the above-mentioned secondary cooling water higher pressure than the above-mentioned coolant, and a water supply pipe is connected to the upper 8-pin system pressure pump. A cooling system for a recirculation bond in a nuclear reactor, characterized in that it is configured to appropriately supply primary cooling water from a water supply pipe. 2. The secondary cooling system is configured to include a current regulating valve upstream of the heat exchanger that lowers the temperature of the secondary cooling water, and to adjust the flow rate of the primary cooling water supplied to the heat exchanger. A cooling system for a recirculation bond in a nuclear reactor according to claim 1.