JPH05341086A - Underwater organic impurity removing system - Google Patents

Abstract

PURPOSE:To remove organic impurities included in the water in a condensate storing tank to be carried in from the condensate storing tank when a hot well in a condenser is to be filled with water before starting. CONSTITUTION:With the outlet from a condensate storing tank 100, an organic impurities decomposing device 103 is connected through a condensate conveying pump 101 and a valve 102. The outlet from this decomposing device 103 is through a valve 104 connected with a condenser 5, whose outlet side is connected with a condensate purifying system consisting of a condensate filtrating device 8, condensate desalting device 9, etc. The outlet from this desalting device 9 is connected with the inlet to the abovementioned condensate storing tank 100 via a high pressure condensate pump 12 and valves 105, 106.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for removing organic impurities in water for decomposing and removing organic impurities brought into a condenser from a condensate storage tank installed in a boiling water nuclear power plant.

[0002]

2. Description of the Related Art A boiling water nuclear power plant (hereinafter referred to as a BWR plant) has a condensate storage tank 100 shown in FIG. Water is supplied into the condenser 5, and water is supplied to the control rod drive system 111 by the control rod drive pump 110.
Water comes in from the condensate purification system.

That is, in FIG. 7, the steam in the reactor pressure vessel 1 flows into the turbine 4 through the main steam line 2 and the main steam stop valve 3 and into the condenser 5 which has finished its work in the turbine 4 and is condensed. To do.

The water in the hot well 6 of the condenser 5 has a low-pressure condensate pump 7 which removes insoluble impurities by a condensate filter 8 of a condensate purification system, and impurities by a condensate demineralizer 9. Removed and purified.

The purified condensate is supplied from the high pressure condensate pump 12 through the low pressure feed water heater 13, the feed water pump 14, the high pressure feed water heater 15 and the valve 16 into the reactor pressure vessel 1 as a coolant.

A water supply recirculation pipe 19 is provided via a water supply recirculation valve 18 to branch from the outlet side pipe of the high pressure water heater 15 and connect it to the condenser 5. A condensate recirculation pipe 27 that branches from the outlet side pipe of the high-pressure condensate pump 12 and connects to the hot well 6 is connected via a condensate recirculation valve 17. Further, condensate demineralizer bypass lines 10 are provided on both sides of the condensate demineralizer 9 via valves 11.

By the way, as a procedure to be carried out before the reactor is started up, following the recovery after the work, all the system of the plant except the system which is constantly operating at that time is lined up to the usable state.

Condensate storage tank in primary system of boiling water reactor
100 water is pressurized by condensate transfer pump 101, and valve 10
Replenish via the 2 to the hot well 6 of the condenser 5. After the water filling in the hot well 6 is completed, the water in the condensate storage tank 100 stored in the hot well 6 is pressurized by the low-pressure condensate pump 7 of the condensate purification system, and the condensate filtering device 8 and the condensate dewatering device are discharged. It is sent to the salt device 9 to remove impurities.

After the impurities are removed, the condensate is pressurized by the high-pressure condensate pump 12 and passed through the condensate recirculation valve 17 to the hot well 6
Returned to. By repeating this, the condensate system purification operation for removing impurities in the condensate line is performed.

Next, the water in the hot well 6 is pressurized by the low-pressure condensate pump 7, and the condensate filter 8 and the condensate demineralizer 9 are supplied.
After being sent to the high pressure condensate pump 12
Pressurized by, through low pressure feed water heater 13, pressurized by feed water pump 14, through high pressure feed water heater 15, feed water recirculation field valve 18
Is returned to the hot well 6 via.

By repeating this, the water supply system cleaning operation is performed. Impurities in the condensate water supply system generated during the outage will be removed by performing the condensate water supply system purification operation to improve the water quality. This is intended to reduce the amount of impurities brought into the reactor at startup.

[0012]

A problem in the condensate storage tank of the BWR plant is an organic impurity which is produced by elution and decomposition of the coating material on the inner surface of the condensate storage tank 100 and accumulated in the tank. Although these organic impurities pass through the condensate filter and condensate demineralizer during the condensate feed water purification operation before startup, most of them are not removed by the condensate filter and condensate desalinizer, so most of them are removed during startup. Brought to the furnace.

On the other hand, the water in the condensate storage tank in which the organic impurities are accumulated is injected as control rod drive water into the control rod drive system and directly carried into the reactor. The above-mentioned organic impurities are decomposed by being exposed to high temperature and high pressure conditions and radiation in the reactor and become various impurities, which cause deterioration of water quality of the reactor.

The present invention has been made to solve the above-mentioned problems, and it is possible to prevent deterioration of water quality of a reactor due to organic impurities brought in from a condensate storage tank during water filling of a hot well before startup. To provide an impurity removal system.

[0015]

According to the present invention, an organic impurity decomposing device is connected to an outlet side of a condensate storage tank installed in a boiling water nuclear power plant via a condensate transfer pump and a valve, and the organic impurity is decomposed. The outlet side of the decomposition device is connected to a condenser via a valve, the outlet side of this condenser is connected to a condensate purification system, and the outlet side of this condensate purification system is the inlet side of the condensate storage tank. It is characterized by being connected to.

[0016]

[Operation] Condensate storage tank → organic impurity decomposition device → hot well → condensate purification system → condensate storage tank Internal water and organic impurities that purify water in the hot well are decomposed and removed by generation of ultraviolet rays or thermal decomposition.

The water in the condensate storage tank from which organic impurities have been removed can be used as control rod driving water, and the purified hot well water can be used for condensate and feed water purification operation. Therefore, it is possible to prevent the organic impurities from being brought into the reactor at the time of startup, and to avoid the influence on the reactor structural material.

[0018]

EXAMPLE An example of the system for removing organic impurities in water according to the present invention will be described with reference to FIGS. In FIG. 1, the same parts as those in FIG. 7 are designated by the same reference numerals, and the description of the overlapping parts will be omitted.

In FIG. 1, the water in the condensate storage tank 100 is pressurized by the condensate transfer pump 101 when the hot well 6 is filled with water before the BWR plant is activated, and the organic impurity decomposing device 103 is passed through the valve 102 and the valve 104 is passed. Is injected into the hot well 6 to cause the water level of the hot well 6 to be exceeded, and the hot well 6 is allowed to flow out to the outlet.

The water flowing out from the hot well 6 is pressurized by a low pressure condensate pump 7, passed through a condensate filter 8 and a condensate demineralizer 9 and pressurized by a high pressure condensate pump 12, and a valve 105,
Returned to the condensate storage tank 100 via 106.

By performing such a recirculation operation, the organic impurities accumulated in the condensate storage tank 100 due to elution and decomposition of the inner coating of the condensate storage tank 100 are decomposed by the organic impurity decomposition device 103, It is removed by the water filtration device 8. The ultraviolet irradiation means shown as a specific example of the organic impurity decomposing device 103 will be described with reference to FIGS.

That is, in order to efficiently decompose organic substances by ultraviolet rays, it is desirable to lengthen the contact time between the ultraviolet rays and the water to be treated to increase the contact area, and the effective distance for ultraviolet rays to decompose organic substances is The optimum distance is 5 to 10 mm from the contact surface of the lamp and the treated water. Actually, the lamp is not soaked in water, but the ultraviolet lamp 21 is housed in the transparent protection tube 22 so that the protection tube 22 and the water contact each other. Protective tube 22
The inside is filled with an inert gas that does not react with ultraviolet rays.

In the first example shown in FIG. 3, the water to be treated is made to flow upward, and the reaction tank 20 is made thicker than the outlet pipe 23 and the inlet pipe 24. The contact time can be extended and the contact area can be increased. Further, by providing a plurality of baffle plates 25 as shown in FIG. 4 showing the second example, it is possible to irradiate the ultraviolet rays more efficiently.

In the third FIG. 5, the water to be treated is atomized from the spray nozzle 26, and the protection tube in which the ultraviolet lamp 21 is inserted.
It is sprayed on 22 to increase the contact area. Further, many ultraviolet lamps 21 can be installed to efficiently decompose organic impurities in the water to be treated.

Thus, in FIG. 2, the condensate storage tank 10
The water in 0 is pressurized by the condensate transfer pump 101 and the valve
It flows into the organic impurity decomposition device 103 via 102. The organic impurity decomposing unit 103 is provided with an ultraviolet lamp 112 for supplying ultraviolet rays for decomposing organic impurities, by which the organic impurities are decomposed and carbon dioxide, organic acids, etc., which can be removed by the condensate filtering unit 8 and the condensate desalting unit 9. It has the function of being a component of.

Water whose organic impurities have been decomposed by passing through the organic impurity decomposition device 103 is sent to the hot well 6 through the valve 104, flows out from the outlet of the hot well 6, is pressurized by the low pressure condensate pump 7, and is recovered. The organic impurities decomposed by the water filtration device 8 and the condensate demineralizer 9 are removed, pressurized by the high-pressure condensate pump 12, and returned to the condensate storage tank 100 via the valves 105 and 106.

The organic impurity decomposing device 103 is provided with a thermal decomposing device by utilizing the fact that the organic impurities are decomposed by heat in addition to the decomposition by ultraviolet rays described in FIGS. The water can also be heat-treated.

Next, another embodiment of the present invention will be described with reference to FIG. In FIG. 6, 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 and only the main parts will be described.

During the condensate water supply system purification operation before startup,
As shown in FIG. 6, the branch line 28 branched from the outlet line of the low-pressure condensate pump 7 is connected to the organic impurity decomposing device 103, and the return line 29 returning to the condensate filtering device 8 is connected to each line 28, 29. Install valves 107, 108, and 109.

As a result, the water from the hot well 6 is pressurized by the high-pressure condensate pump 7, the valve 107 is kept closed, and the water is sent to the organic impurity decomposition apparatus 103 via the valve 108 to decompose the organic impurities.

The decomposed treated water is returned to the return line 29 via the valve 109, and the condensate filtering device 8 and the condensate desalting device 9 are returned.
Condensate recirculation valve that removes organic impurities decomposed in 18
The condensate system purification operation of returning to the hot well 6 via the is performed.

Next, in order to carry out the water supply system purification operation, the water in the hot well 6 follows the same line as the condensate water purification operation up to the high-pressure condensate pump 12, and then the low-pressure feed water heater.
High-pressure feed water heater 15 pressurized by feed water pump 14
Through the water supply recirculation valve 18 to the hot well 6.

The organic impurities generated by the decomposition of the ion exchange resin in the condensate demineralizer 9 by performing the condensate water supply system purification operation by such means are similar to the organic impurities generated from the condensate storage tank 100. Can be removed.

[0034]

According to the present invention, it is possible to decompose and remove the organic impurities contained in the water in the condensate storage tank and the organic impurities generated from the condensate demineralizer, and The water quality of the boiling water reactor primary system can be maintained at high purity. As a result, the soundness of the nuclear reactor structural material is maintained, and the reliability and life of the nuclear power plant can be improved.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a system for removing organic impurities in water according to the present invention.

FIG. 2 is a system diagram showing an enlarged main part in FIG.

FIG. 3 is a schematic diagram showing a first example of the organic impurity decomposing apparatus in FIG.

FIG. 4 is a schematic diagram showing a second example of the organic impurity decomposing apparatus in FIG.

FIG. 5 is a schematic diagram showing a third example of the organic impurity decomposing apparatus in FIG.

FIG. 6 is a system diagram showing another example of a system for removing organic impurities in water according to the present invention.

FIG. 7 is a system diagram showing an outline of a boiling water nuclear power plant for explaining a conventional example.

[Explanation of symbols]

1 ... Reactor pressure vessel, 2 ... Main steam line, 3 ... Main steam stop valve, 4 ... Turbine, 5 ... Condenser, 6 ... Hot well,
7 ... Low-pressure condensate pump, 8 ... Condensate filtering device, 9 ... Condensate demineralizer, 10 ... Condensate demineralizer bypass line, 12 ... High-pressure condensate pump, 13 ... Low-pressure feed water heater, 14 ... Water feed pump , 15 ... High-pressure water heater, 17 ... Condensate recirculation valve, 18 ... Water recirculation valve, 19 ... Water recirculation pipe, 20 ... Reactor, 21 ... UV lamp, 22 ... Protection tube, 23 ... Outlet tube, 24 ... Inlet pipe, 25 ... Baffle plate, 26 ... Spray nozzle, 27 ... Condensate recirculation pipe, 28
... Branching line, 29 ... Return line, 100 ... Condensate storage tank, 101 ... Condensate transfer pump, 103 ... Organic impurity decomposition device, 110 ... Control rod drive pump, 111 ... Control rod drive system, 11
2… UV lamp, 11, 16, 102, 104 to 109… Bulb.

Claims (1)

[Claims] 1. An organic impurity decomposing device is connected to an outlet side of a condensate storage tank installed in a boiling water nuclear power plant via a condensate transfer pump and a valve, and an outlet side of the organic impurity decomposing device is connected to a valve. Connect to the condenser via
A system for removing organic impurities in water, characterized in that an outlet side of the condenser is connected to a condensate purification system, and an outlet side of the condensate purification system is connected to an inlet side of the condensate storage tank.