JPH0366636B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an emergency cooling system for ensuring cooling of an internal pump of a boiling water nuclear reactor when a cooling water leakage accident occurs in the internal pump.

[Technical background of the invention]

In general, boiling water reactors are equipped with multiple jet pumps inside the reactor pressure vessel, and a portion of the cooling water inside the reactor pressure vessel is taken out of the reactor pressure vessel and is pressurized by a recirculation pump. The jet pumps were fed with driving water, and these jet pumps recirculated the cooling water in the reactor pressure vessel through the reactor core.

Incidentally, recently, a system has been developed in which an internal pump is used instead of the jet pump to circulate cooling water within the reactor pressure vessel. 1st
A boiling water reactor equipped with such an internal pump is shown in FIG. In the figure, 1 indicates a reactor pressure vessel, and a shroud 2 is provided in this reactor pressure vessel 1.
A reactor core 3 is housed inside. A plurality of internal pumps 4 are provided at the bottom of the reactor pressure vessel 1. The cooling water in the reactor pressure vessel 1 is sent from below into the reactor core 3 by these internal pumps 4..., boils within the reactor core 3, becomes a two-phase flow of water and steam, and is sent upward. . This two-phase flow of water and steam is separated into water and steam by the steam separator 5, and the separated water is pumped into the core 3 again by the internal pumps 4 along with the feed water supplied from the feed water spargeer 6. flows in and circulates through this path. In addition, the separated steam is subjected to moisture removal in a steam dryer 7, and then to a main steam nozzle 8,
8, sent to the turbine via the main steam pipe (not shown).

The internal pump 4 described above is constructed as shown in FIG. That is, in the figure, reference numeral 10 denotes a motor casing, which has a watertight structure, and its tip is inserted from the outside into a nozzle 19 provided in the lower mirror section of the reactor pressure vessel 1. It is welded to the part. A water-immersed motor section 11 is housed within the motor casing 10. 12 is its rotating shaft, and this rotating shaft 12 has radial bearings 13, 13 and thrust bearings 14, 14.
is supported by. In addition, this rotating shaft 12
An impeller 15 is provided at the lower end of the motor casing 10, and the impeller 15 is configured to circulate cooling water within the motor casing 10. Note that 16 is a stator and 17 is a rotor. Also,
Reference numeral 20 denotes a pump section, which is composed of a differential user 21 and an impeller 22. The differential user 21 is seated at the tip of the nozzle 19 and is fixed by a stretch tube 23 and a stretch tube nut 24. The impeller 22 and the rotating shaft 12 of the motor section 11 are connected by a pump shaft 25. Therefore, this impeller 22 is connected to the pump shaft 2
5 and is driven by the motor section 11 to send the cooling water in the reactor pressure vessel 1 downward. Further, a cooling water inlet pipe 30 and a cooling water outlet pipe 31 are connected to the lower end and the upper end of the motor casing 10, respectively.
It is connected to the. And motor casing 1
0 is circulated through the heat exchanger 32 by the impeller 15 attached to the lower end of the rotating shaft 12, and this cooling water is heat exchanged with external cooling water by the heat exchanger 32. and this motor part 11
to cool down.

Furthermore, a labyrinth portion 33 is provided on the inner circumferential surface of the stretch tube 23, and the high temperature cooling water in the reactor pressure vessel 1 flows between the inner circumferential surface of the stretch tube 23 and the outer circumferential surface of the pump shaft 25. This prevents the fluid from flowing into the motor casing 10 through the gap between the two. Also, motor casing 1
An inflation seal 34 is provided on the upper part of the 0, and when the motor section 11 is removed, this inflation seal 34 is connected via a pressure water supply pipe 35.
Pressurized water is supplied to inflate the inflation seal 34 and bring it into close contact with the outer peripheral surface of the pump shaft 25, thereby preventing the cooling water in the reactor pressure vessel 1 from leaking when the motor casing 10 is opened. do.
Further, a purge water supply pipe 36 is connected to the upper inside of the motor casing 10. The motor casing 1 is then connected to the motor casing 1 via this purge water supply pipe 36.
Purge water is supplied into the motor casing 10, and this purge water flows to the reactor pressure vessel 1 side through the labyrinth part 33, preventing high temperature cooling water in the reactor pressure vessel 1 from flowing into the motor casing 10. are doing.

[Problems with background technology]

A cooling water inlet pipe and a cooling water outlet pipe are connected to the motor casing, and a temperature detector for detecting the temperature of the radial bearing and the thrust bearing is provided to penetrate the motor casing. Therefore, if the cooling water inlet pipe, the cooling water outlet pipe, the temperature sensor, etc. are damaged, the cooling water in the motor casing may leak. When a large amount of the cooling water inside the motor casing leaks out, the pressure inside the motor casing becomes low, and as a result, the high temperature cooling water inside the reactor pressure vessel flows into the motor casing through the labyrinth portion. Therefore, this high-temperature cooling water may damage insulators such as the stator of the motor section, leading to damage to the motor section.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to ensure cooling of the motor section and prevent damage to the motor section when cooling water inside the motor casing leaks. The purpose of the present invention is to provide an emergency cooling device for an internal pump.

[Summary of the invention]

The present invention detects the temperature or pressure of the cooling water in the motor casing of an internal pump that circulates the cooling water in the reactor pressure vessel, and detects leakage of the cooling water in the motor casing by increasing the temperature or decreasing the pressure of this cooling water. The motor is equipped with a cooling water leakage detection mechanism that detects the leakage, and an emergency cooling water supply mechanism that receives a signal from the cooling water leakage detection mechanism and supplies emergency cooling water into the motor casing in the event of a cooling water leakage accident. . Therefore, in the event that a leakage accident of cooling water inside the motor casing occurs, emergency cooling water will be supplied into the motor casing from the emergency cooling water supply mechanism to ensure cooling of the motor, and the reactor This can reliably prevent the motor section from being damaged by high-temperature cooling water from inside the pressure vessel.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to FIGS. 3 to 5. FIG. 1 shows a boiling water nuclear reactor equipped with an internal pump, and 101 in the figure is a reactor pressure vessel. This reactor pressure vessel 101
A shroud 102 is provided inside, and a reactor core 103 is accommodated within this shroud 102. A plurality of internal pumps 104 are provided at the bottom of the reactor pressure vessel 101, and the cooling water in the reactor pressure vessel 101 is pumped from below into the reactor core.
03, it boils in this core 103, becomes a two-phase flow of water and steam, and is sent upward. This two-phase flow of water and steam is separated into water and steam by a steam separator 105, and the separated water is sent to the supply spargeer 10.
The water flows into the core 103 again by the internal pumps 104 along with the water supplied from the reactor 6, and circulates through this path. Further, the separated steam is subjected to moisture removal in a steam dryer 107, and then to main steam nozzles 108, 108, and a main steam pipe (not shown).
is sent to the turbine via the

Then, the above internal pump 104 is connected to the second
It is configured as shown in the figure. In other words, 1 in the figure
Reference numeral 10 denotes a motor casing having a watertight structure, the tip of which is inserted from the outside into a nozzle 119 provided in the lower mirror section of the reactor pressure vessel 101, and is welded to the tip of this nozzle 119. There is. A water immersion type motor section 111 is housed within this motor casing 110. 11
Reference numeral 2 denotes its rotating shaft, and this rotating shaft 112 is supported by radial bearings 113, 113 and thrust bearings 114, 114. Further, an impeller 115 is provided at the lower end of this rotating shaft 112, and this impeller 115
The cooling water in the motor casing 110 is configured to be circulated by the motor casing 110. Note that 116 is a stator and 117 is a rotor. Further, 120 is a pump section, which is composed of a differential user 121 and an impeller 122. The differential user 121 is seated at the tip of the nozzle 119 and is fixed by a stretch tube 123 and a stretch tube nut 124. This impeller 122 and the rotating shaft 112 of the motor section 111 are connected by a pump shaft 125. Therefore, this impeller 12
2 is driven by the motor section 111 via the pump shaft 125, and sends the cooling water in the reactor pressure vessel 101 downward. In addition, the motor casing 11
A cooling water inlet pipe 130 and a cooling water outlet pipe 131 are connected to the lower and upper ends of the cooling water inlet pipe 130 and the cooling water outlet pipe 131, respectively, and the cooling water inlet pipe 130 and the cooling water outlet pipe 131 are connected to a heat exchanger 132. The cooling water inside the motor casing 110 is circulated through the heat exchanger 132 by an impeller 115 attached to the lower end of the rotating shaft 112, and this cooling water is circulated by the heat exchanger 132 to the outside. This motor section 11 undergoes heat exchange with water.
Cool 1.

Further, a labyrinth portion 133 is provided on the inner circumferential surface of the stretch tube 123, and the high temperature cooling water in the reactor pressure vessel 101 flows between the inner circumferential surface of the stretch tube 123 and the outer circumferential surface of the pump shaft 125. motor casing 1 through the gap between
This prevents the liquid from flowing into the interior of the 10. Further, an inflation seal 134 is provided on the upper part of the motor casing 110, and when the motor section 111 is removed, pressure water is supplied to this inflation seal 134 via a pressure supply pipe 135 to prevent the inflation. The seal 134 is expanded and brought into close contact with the outer circumferential surface of the pump shaft 125 to prevent cooling water in the reactor pressure vessel 101 from leaking when the motor casing 110 is opened. Further, a purge water supply pipe 136 is connected to the upper inside of the motor casing 110. Then, purge water is supplied into the motor casing 110 through this purge water supply pipe 136, and this purge water flows to the reactor pressure vessel 101 side through the labyrinth part 133, and the high temperature inside the reactor pressure vessel 101. Cooling water is prevented from flowing into the motor casing 110.

An emergency cooling water supply pipe 140 is connected to the upper part of the motor casing 110.
This emergency cooling water supply pipe 140 is connected to an emergency cooling water supply mechanism 141. This emergency cooling water supply mechanism 141 is composed of a pump 142 and a valve 143, and includes a water source 1 such as a pressure suppression chamber.
44 is applied by the pump 142, and the valve 143 and the emergency cooling water supply pipe 1
40 into the motor casing 110.

Further, 150 is a cooling water leak detection mechanism. This cooling water leakage detection mechanism 150 includes a temperature detector 151
and a control circuit 152. The temperature detector 151 is attached to the upper part of the motor casing 110.
The temperature of the coolant within 0 is configured to be detected. The detection signal of this temperature detector 151 is then sent to the control circuit 152 described above. This control circuit 152 sends a start signal to the pump 142 of the emergency cooling supply mechanism 141 when the temperature of the cooling water in the motor casing 110 detected by the temperature detector 151 rises above the temperature during normal operation. The lever pump 142 is started, and the discharge amount of the pump 142 is controlled in accordance with the temperature of the cooling water in the motor casing 110 to maintain the temperature of the cooling water in the motor casing 110 at a predetermined temperature or lower. It is configured as follows.

In the first embodiment of the present invention configured as described above, normally, the cooling water in the motor casing 110 is circulated through the heat exchanger 132 by the impeller 115 attached to the lower end of the rotating shaft 112 of the motor section 111. Ru. Therefore, the heat generated in the motor section 111 and the heat transferred from the reactor pressure vessel 101 side are released to the external cooling water via the heat exchanger 132, and the cooling water inside the motor casing 110 is kept constant. maintained at a temperature of

If the cooling water inlet pipe 130, the cooling water outlet pipe 131, etc. are damaged and the cooling water inside the motor casing 110 leaks to the outside, the pressure inside the motor casing 110 decreases, and the pressure inside the reactor pressure vessel 101 decreases. The high temperature cooling water of the labyrinth part 13
3 into the motor casing 110. As a result, the temperature of the cooling water within the motor casing 110 increases. The temperature rise in the cooling water is detected by the temperature detector 151, and a start signal is sent from the control circuit 152 to the pump 142 of the emergency cooling water supply mechanism 141.
starts and supplies low-temperature emergency cooling water into the motor casing 110. Therefore, this emergency cooling water mixes with the high-temperature cooling water flowing into the motor casing 110 through the labyrinth portion 133 and becomes low temperature, thereby preventing the temperature inside the motor casing 110 from rising. Further, the discharge amount of the pump 142, that is, the supply amount of emergency cooling water, is controlled in accordance with the temperature inside the motor casing 110, and the temperature of the cooling water inside the motor casing 110 is maintained below a predetermined temperature. Therefore, in the event of such a cooling water leakage accident, damage to the motor section 111 due to high temperature cooling water flowing in from the reactor pressure vessel 101 side can be prevented.

Further, FIG. 6 shows a second embodiment of the present invention.
This second embodiment uses a pressure detector 153 in place of the temperature detector 151 in the first embodiment. This second embodiment detects a pressure drop in the motor casing 110 due to leakage of cooling water, starts the pump 142, and controls the discharge amount of the pump 142 in accordance with the amount of pressure drop. This second embodiment has the same configuration as the first embodiment except for the above points, and the same reference numerals are given to the parts corresponding to the first embodiment in FIG. 6 and the explanation thereof will be omitted. .

Further, FIG. 7 shows a third embodiment of the present invention.
In this third embodiment, the control circuit 152 controls the pump 1.
Instead of controlling the valve 42, the valve 143 is opened and closed, and the degree of opening is controlled. The third embodiment has the same structure as the first embodiment except for the above points.

Further, FIG. 8 shows a fourth embodiment of the present invention.
In this fourth embodiment, similarly to the third embodiment, a control circuit 152 controls the opening and closing of the valve 143 and also controls the degree of opening. Note that the cooling water leak detection mechanism 150 of this fourth embodiment has the same configuration as that of the second embodiment.

Further, FIG. 9 shows a fifth embodiment of the present invention.
In this fifth embodiment, the emergency cooling water supply mechanism 141 is also used as a purge water supply system. That is, in this fifth embodiment, a purge water supply pipe 155 is branched from the discharge side of the pump 142, and this purge water supply pipe 155 is connected to the upper part of the motor casing 110, and a flow rate adjustment device is installed in the middle of this purge water supply pipe 155. A valve 156 is provided, and the other structure is the same as that of the third embodiment. In this fifth embodiment, the pump 142 is always operated,
Since the valve 143 is normally closed, the cooling water discharged from the pump 142 flows through the flow rate adjustment valve 15.
6, the flow rate is adjusted, and the water is supplied as purge water into the motor casing 110 via the purge water supply pipe 155. When a leakage accident of cooling water inside the motor casing 110 occurs, the valve 143 is opened and a large flow of cooling water is supplied into the motor casing 110 via the emergency cooling water supply pipe 140. Prevents temperature rise within motor casing 110.

Further, FIG. 10 shows a sixth embodiment of the present invention. This sixth embodiment uses a pressure detector 153 in place of the temperature sensor 151 in the fifth embodiment, and the other configurations are the same as those of the fifth embodiment.

Furthermore, the present invention is not limited to each of the above-described embodiments; for example, the discharge amount of the pump or the opening degree of the valve does not necessarily have to be controlled in accordance with the temperature or pressure inside the motor casing; The pump may be started or stopped or only the valve may be opened or closed in response to a rise in temperature or a fall in pressure.

〔Effect of the invention〕

As described above, the present invention detects the temperature or pressure of the cooling water in the motor casing of the internal pump that circulates the cooling water in the reactor pressure vessel, and detects the temperature or pressure of the cooling water in the motor casing by increasing the temperature or decreasing the pressure of the cooling water. and an emergency cooling water supply mechanism that receives a signal from the cooling water leakage detection mechanism and supplies emergency cooling water into the motor casing in the event of a cooling water leakage accident. It is something. Therefore, in the event that a leakage accident of cooling water inside the motor casing occurs, emergency cooling water will be supplied into the motor casing from the emergency cooling water supply mechanism to ensure cooling of the motor, and the reactor This has great effects, such as being able to reliably prevent the motor section from being damaged by high-temperature cooling water from inside the pressure vessel.

[Brief explanation of drawings]

1 and 2 show a conventional example, with FIG. 1 being a longitudinal sectional view of a boiling water nuclear reactor, and FIG. 2 being a longitudinal sectional view of an internal pump. 3 to 5 show a first embodiment of the present invention, FIG. 3 is a longitudinal sectional view of a boiling water reactor, FIG. 4 is a longitudinal sectional view of an internal pump, and FIG. 5 is a schematic configuration. It is a diagram. Fig. 6 is a schematic diagram of the second embodiment, Fig. 7 is a schematic diagram of the third embodiment, Fig. 8 is a schematic diagram of the fourth embodiment, and Fig. 9 is a schematic diagram of the fifth embodiment. Figure 10 is the 6th
FIG. 1 is a schematic configuration diagram of an example. 101...Reactor pressure vessel, 103...Reactor core,
104...Internal pump, 110...Motor casing, 111...Motor section, 141...Emergency cooling water supply mechanism, 142...Pump, 150
... Cooling water leak detection mechanism, 151 ... Temperature detector, 153 ... Pressure detector.

Claims (1)

[Claims] 1. Detects the temperature or pressure of the cooling water in the motor casing of the internal pump that circulates the cooling water in the reactor pressure vessel, and detects leakage of the cooling water in the motor casing based on the temperature rise or pressure drop of this cooling water. Equipped with a cooling water leakage detection mechanism and an emergency cooling water supply mechanism that receives a signal from the cooling water leakage detection mechanism and supplies emergency cooling water into the motor casing of the internal pump in the event of a cooling water leakage accident. An emergency cooling system for internal pumps featuring: