JPH07318687A - Coolant purification system for reactor - Google Patents

Abstract

PURPOSE:To enhance the reliability and safety by backing up and diversifying the function of the purification system for a pressure suppression pool. CONSTITUTION:A pressure vessel 2 in a reactor container 1 is coupled with a valve 14 isolating the inside and outside of a suction line. A pressure suppression pool 3 installed under the reactor container 1 is coupled with an S/P water suction piping 17 through an S/P water suction/isolation valve 18. The S/P water suction piping 17 is coupled through an S/P water suction valve 19 with a regenerative heatexchanger 4 and a non-regenerative heat-exchanger 5. The isolation valve 14 is coupled, on the downstream side thereof, with the regenerative heat-exchanger 4. The non-regenerative heat-exchanger 6 is coupled, on the downstream side thereof, with a pump 6, an inlet valve 15 and a filtering/ desalting tower 7 for reactor coolant purification system, a blow-down flow regulation valve 11, the pressure suppression pool, and a collection tank for low conductivity waste liquid system. When the system is isolated due to low reactor water level and the normal function can not be expected, functions of the pump, heat-exchangers, etc., are utilized effectively to contribute to the enhancement of safety.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactor coolant purification system installed in a nuclear power plant.

[0002]

2. Description of the Related Art A boiling water nuclear power plant is usually equipped with a reactor coolant purification system for purifying the primary coolant, lowering the electrical conductivity of the reactor water, and removing the radiation source. The conventional nuclear reactor purification system has a structure as shown in FIG.
That is, the primary coolant held in the reactor pressure vessel 2 stored in the reactor containment vessel 1 is sucked in, and the filter desalting tower 7 is passed through the regenerative heat exchanger 4, the non-regenerative heat exchanger 5 and the pump 6. To purify the primary coolant.

Then, it is returned to the reactor pressure vessel 1 through the regenerative heat exchanger 4, or returned to the reactor pressure vessel 1 without passing through the regenerative heat exchanger 4, or pressure is passed without passing through the regenerative heat exchanger 4. Suppression pool 3 or low conductivity waste liquid system (LC
W) It is returned to the collection tank.

In FIG. 3, reference numeral 8 is a filter desalting tower bypass valve, 9 is a regenerative heat exchanger bypass valve (manual), 10 is an injection valve to a condensate water supply system, 11 is a blowdown flow rate control valve, and 12 Is a blow line orifice bypass valve, 13 is a blow line pressure suppression pool (S / P) side outlet valve, 14 is a suction line inside and outside isolation valve, 15 is a filter desalting tower inlet valve, 16 is a regenerative heat exchanger inlet valve Are shown respectively.

The cooling water flowing out of the reactor pressure vessel 2 is cooled by the regenerative heat exchanger 4 and the non-regenerative heat exchanger 5,
It is purified by the filter desalting tower 7 through the reactor coolant purification system pump 6, and is again returned from the condensate water supply system to the reactor pressure vessel 1 through the regenerative heat exchanger 4. In this configuration, the system has no function when the isolation valve 14 of the suction line is closed due to the decrease in reactor water level.

[0006]

The operation of the conventional reactor coolant purification system is performed when the water level in the reactor pressure vessel 2 is normal, and the water level in the reactor pressure vessel 2 decreases (L
In the case of -2), the system is isolated by the isolation valve 14 and all the functions are stopped. Therefore, although the pump 6, the heat exchangers 4,5, and the filter desalting tower 7 are provided and have the functions of heat removal and purification, there is a problem that the equipment is not used under such circumstances. .

In the boiling water reactor, when the reactor pressure drops, the functions to be achieved for maintaining the soundness of the nuclear power plant include the function of injecting water into the core for cooling the core and the function of the reactor. 3 functions of a spray function to the reactor containment vessel 1 for cooling the atmosphere in the containment vessel 1 and removal of fission products, and a cooling function of the pressure suppression pool for preventing damage to the containment vessel 1 and removing decay heat. There are types. In boiling water reactors, these are achieved by using multiple systems depending on the type of reactor.

Further, purification of the pressure suppression pool 3 is effective in reducing radiation exposure, and in the improved boiling water reactor and some of the boiling water reactors, a pressure suppression pool cleaning system or a system similar to it is necessary. However, no pressure suppression pool purification system is installed in other boiling water reactors.

The present invention has been made to solve the above problems, and effectively utilizes the pump, heat exchanger, and filter demineralization tower of the reactor coolant purification system to realize the function of the pressure suppression pool purification system. It is to provide a reactor coolant purification system with backup and diversification to improve reliability and safety.

[0010]

According to the present invention, a recirculation system pipe of a reactor pressure vessel is branched and penetrates a reactor containment vessel to a regenerative heat exchanger, and a suction line is provided inside a suction line and through an outer isolation valve. In a reactor coolant purifying system, which is connected to the non-regenerating heat exchanger, a reactor coolant purifying system pump, and a filter desalting tower, is provided on the reactor containment vessel on the downstream side of the regenerative heat exchanger. A suction pipe is connected to the lower portion of the pressure suppression pool via an isolation valve, and this suction pipe is connected to the connection pipe between the regenerative heat exchanger and the non-regenerative heat exchanger via the suction valve. It is characterized by

[0011]

[Function] A suction pipe from the pressure suppression pool can be installed in the reactor coolant purification system, and the pressure suppression pool can be used as a water source to inject water into the reactor pressure vessel and return to the pressure suppression pool. This will contribute to the diversification of the system having the water injection function and the system having the cooling and purification functions of the pressure suppression pool.

[0012] Further, by removing heat and purifying even under the condition that the reactor coolant purification system has not been functioning in the past, the versatility of these functions is added to the reactor coolant purification system, and by extension, nuclear power Achieve improved reliability and safety of the power plant.

[0013]

EXAMPLE A first example of the reactor coolant purification system according to the present invention will be described with reference to FIG. In FIG. 1, the reactor pressure vessel 2 stored in the reactor containment vessel 1 is connected to the suction line inside / outside isolation valve 14. This isolation valve
14 is connected to the regenerated heat exchanger 4, and the regenerated heat exchanger 4 is connected to the non-regenerated heat exchanger 5.

A filter 20 is provided in the pressure suppression pool 3 installed below the reactor containment vessel 1, and an S / P suction pipe 17 is provided on the lower surface of the pressure suppression pool 3 with an S / P water suction isolation valve 18. Connected through.

The downstream side of this S / P water suction pipe 17 is S / P
Regeneration heat exchanger 4 and non-regeneration heat exchanger 5 via water suction valve 19
It is connected to the pipe between. The non-regenerated heat exchanger 5 is connected to the reactor coolant purification system pump 6. This pump 6
The discharge side is connected to the reactor coolant purification system filter desalting tower 7 through a filter desalting inlet valve 15.

On the outlet side of this filtration desalination tower 7, a regenerative heat exchanger bypass valve (electric) 9 and a regenerative heat exchanger inlet valve (electric)
16 and the blowdown flow control valve 11 are connected. The downstream side of the blowdown flow rate control valve 11 is connected to a pressure suppression pool via a low conductivity waste liquid collection tank and a blow line S / P side outlet valve 13.

The downstream side of the regenerative heat exchanger bypass valve 11 is connected via the injection valve 10 to the condensate water supply system and the pipe connected to the top of the reactor pressure vessel 2 via the valve. In the figure, reference numeral 8
Is a filtration desalting tower bypass valve, and 12 is a blow line orifice bypass valve.

However, in the above-described embodiment, during normal operation, the operation is performed with the same configuration as the conventional reactor coolant purification system as shown in the figure. When the water level in the reactor is lowered and the inner and outer isolation valves 14 are closed, the S / P water suction isolation valve 18 and the S / P water suction valve on the S / P water suction pipe 17 are closed.
Open 19 to allow suction from the pressure suppression pool 3. In order to reduce the pressure loss in the discharge pipe, the regenerative heat exchanger bypass valve 9 and the regenerative heat exchanger inlet valve 16 are electrically operated to enable remote operation.

In the present invention, since the suction from the pressure suppression pool 3 is possible, it is possible to inject the pressure suppression pool water into the reactor pressure vessel 1, cool the pressure suppression pool 3, and purify the pressure suppression pool 3. did.

In the operation of injecting the pressure suppression pool water into the reactor pressure vessel 1, the suction line isolation valve 14 is fully closed and then the filter desalting tower inlet valve 15 and the regenerative heat exchanger inlet valve 16 are fully closed. . After that, the S / P water suction isolation valve 18, the S / P water suction valve 19, the filter desalting tower bypass valve 8 and the regenerative heat exchanger bypass valve 9 are fully opened, and the reactor pressure is passed from the pressure suppression pool 3 through the condensate water supply system. Water is poured into the container 1.

This operation can be performed when the reactor pressure is sufficiently low and at the time of periodical inspection. Especially, by adding a system capable of injecting water when the reactor is stopped, the reliability at the time of shutdown can be improved. And improved safety is achieved.

In the operation of cooling the pressure suppression pool 3, the suction line isolation valve 14 is fully closed, and then the filter desalting tower inlet valve 15 and the regenerative heat exchanger inlet valve 16 are fully closed to suck the S / P water. Isolation valve 18, S / P water suction valve 19, Filtration desalting tower bypass valve 8, Blowdown flow rate adjusting valve 11, Blowline orifice bypass valve 12, Blowline S / P side outlet valve 13 are fully opened and pressure suppression pool 3 Form a line that circulates
The non-regenerated heat exchanger 5 cools the pressure suppression pool water.

Thus, by backing up the pressure suppression pool cooling function of the residual heat removal system, the cooling system is diversified and the reliability and safety are improved.

In the operation for purifying the pressure suppression pool 3, the suction line isolation valve 14 is fully closed, and then the filter desalting tower inlet valve 15 and the regenerative heat exchanger inlet valve 16 are fully closed to suck the S / P water. Isolation valve 18, S / P water suction valve 19, blowdown flow rate adjusting valve 11, blowline orifice bypass valve 12, blowline S / P side outlet valve 13 are fully opened to form a line for circulating the pressure suppression pool 3. The pressure control pool water is purified by the filter desalting tower 7.

According to the first embodiment, by backing up the function of the pressure suppression pool purification system, diversification is achieved and improvement in reliability and safety is achieved.

Next, a second embodiment of the reactor coolant purification system according to the present invention will be described with reference to FIG. In addition, in FIG.
The same parts as those in FIG. 1 are designated by the same reference numerals, and the description of the overlapping parts will be omitted.

Reference numeral 21 in FIG. 2 denotes a condensate storage tank, which connects the condensate storage tank 21 and the pressure suppression pool 3 to a condensate supply pipe 23 via a pump 22. A suction pipe 24 is branched from the condensate supply pipe 23 and connected via a suction valve 25, and the suction pipe 24 is connected to the suction pipe 17.

According to this second embodiment, the suction pipe 24 from the condensate storage tank 21 is pumped in the reactor coolant purification system.
Since it is installed on the upstream side of 22, it is possible to diversify the water source and avoid lowering the water level of the pool water in the pressure suppression pool 3.

[0029]

According to the present invention, when the system is isolated due to the low reactor water level in the reactor pressure vessel and normal functions cannot be expected, pumps, heat exchangers and other devices are effectively used, The reliability and safety of nuclear power plants can be improved.

Further, by having the capability of injecting water from the water source into the reactor pressure vessel, it is possible to diversify the water injection system when the pressure inside the reactor pressure vessel is reduced, and further, suction from the pressure suppression pool, By returning to the pressure suppression pool, the pressure suppression pool water can be cooled by the non-regeneration heat exchanger.

[Brief description of drawings]

FIG. 1 is a system diagram showing a first embodiment of a reactor coolant purification system according to the present invention.

FIG. 2 is a system diagram showing a second embodiment of a reactor coolant purification system according to the present invention.

FIG. 3 is a system diagram showing a conventional reactor coolant purification system.

[Explanation of Codes] 1 ... Reactor containment vessel, 2 ... Reactor pressure vessel, 3 ... Pressure suppression pool, 4 ... Regenerative heat exchanger, 5 ... Non-regenerative heat exchanger, 6
... Reactor coolant purification system pump, 7 ... Filtration desalting tower, 8 ... Filtration desalting tower bypass valve, 9 ... Regenerative heat exchanger bypass valve (electric), 10 ... Injection valve, 11 ... Blowdown flow control valve, 12 ...
Blow line orifice bypass valve, 13 ... Blow line S / P side outlet valve, 14 ... Suction line inside / outside isolation valve, 15
... Filter desalting tower inlet valve, 16 ... Regenerative heat exchanger inlet valve (electric), 17 ... S / P water suction pipe, 18 ... S / P water suction isolation valve, 19 ... S / P water suction valve, 20 ... Filter, 21 ... Condensate storage tank, 22 ... Condensate storage tank pump, 23 ... Condensate supply pipe, 24 ... Condensate suction pipe, 25 ... Suction valve.

Claims (4)

[Claims] 1. A regenerative heat exchanger, which is branched from a recirculation system pipe of a reactor pressure vessel, penetrates the reactor containment vessel, and is connected to a regenerative heat exchanger through suction line inner and outer isolation valves. In the reactor coolant purification system in which a non-regenerative heat exchanger, a reactor coolant purification system pump, and a filter demineralization tower are connected on the downstream side of the reactor, the lower part of the pressure suppression pool provided in the reactor containment vessel. Connect the suction pipe via the isolation valve to
A reactor coolant purification system characterized in that the suction pipe is connected to a connection pipe between the regenerative heat exchanger and the non-regenerative heat exchanger via a suction valve. 2. The reactor coolant purification system according to claim 1, wherein the suction pipe is connected to an upstream pipe of the reactor coolant purification pump. 3. The nuclear reactor coolant purification system according to claim 1, wherein the suction pipe is connected to a condensate storage tank. 4. The reactor coolant purification system according to claim 3, wherein the suction pipe from the condensate storage tank is connected to an upstream side of the reactor coolant purification system pump.