JP7062568B2 - Water treatment method and water treatment preparation method for nuclear power plants - Google Patents

Description

An embodiment of the present invention is a water treatment method for a nuclear power plant that purifies and treats the possessed water held in the nuclear power plant during the shutdown period of the nuclear power plant, and a nuclear power generation prepared for implementing the water treatment method. Regarding the method of preparing for water treatment at the power plant.

A large amount of water is held in a nuclear power plant where power generation operations are suspended for the purpose of cooling nuclear fuel. For example, a large amount of water is stored and held in a reactor well, a suppression chamber, a spent fuel storage pool, and a condensate purification system facility. During the shutdown period of the nuclear power plant, the purification treatment of water is delayed compared to the operation, and these waters contain more impurities such as clads than the operation. Moreover, this impurity contains radioactive substances.

When shifting from the shutdown state of a nuclear power plant to decommissioning, in order to dismantle the equipment that holds the above water, the water in the equipment to be dismantled is transferred before dismantling, and impurities including radioactive substances are removed. Therefore, it is necessary to purify this water. In addition, even when restarting a nuclear power plant that has been shut down, it is necessary to purify the water inside the nuclear power plant in the same way in order to ensure stable operation of the plant and reduce the exposure of workers during operation. .. Hereinafter, the water held and accumulated in the nuclear facility during the shutdown is referred to as the held water. In addition, the nuclear power plant is out of service when it is not engaged in power generation work, and some equipment such as the fuel pool cooling and purification system is in operation for cooling and inspection of nuclear fuel. There is.

Japanese Unexamined Patent Publication No. 2014-52251

Until now, water that has been used and discarded in nuclear power plants has been purified using existing waste treatment equipment.

Even in the decommissioning of nuclear power plants and preparations for restarting nuclear power plants that have been out of service for a long period of time, a large amount of water possessed will be treated using existing waste treatment equipment as before. .. Although the amount of water held in such nuclear power plants that requires purification treatment is large, the treatment capacity per unit time that can be purified by waste treatment equipment is relatively small compared to the amount of water held.
Therefore, a large amount of water held in the reactor wells, suppression chambers, spent fuel storage pools and condensate purification system facilities of these nuclear power plants is treated as waste according to the treatment capacity of the existing waste treatment facilities. If the water is transferred to the equipment for purification treatment, it may take several months until the purification treatment of the retained water is completed, and the burden on the existing waste treatment equipment is large. Furthermore, during that time, work for dismantling and restarting the above equipment such as reactor wells and suppression chambers could not be started, and the construction period for decommissioning nuclear power plants and preparing for restart may be prolonged. ..

The embodiment of the present invention has been made in consideration of the above-mentioned circumstances, and is a water treatment method and a water treatment preparation method for a nuclear power plant that can efficiently carry out purification treatment of retained water in a stopped nuclear power plant. The purpose is to provide.

The water treatment method of a nuclear power plant according to the embodiment of the present invention is a water treatment method of a nuclear power plant that treats the water possessed in the nuclear power plant during the shutdown period of the nuclear power plant, and is a nuclear reactor in the nuclear power plant. The first transfer step of transferring the retained water held in at least one of the well, the fuel storage pool, the suppression chamber, and the condensate storage facility to the main dewatering unit in the reactor building, and the transfer to the main dewatering unit. It has a purification step of purifying the retained water in the condensate purification system facility inside the reactor building and a second transfer step of transferring the retained water purified in the purification step to the outside of the reactor building. The first transfer step is characterized in that the retained water held in the reactor well is transferred to the main water recovery device via the recovery water storage facility .

The method for preparing water treatment for a nuclear power plant according to the embodiment of the present invention is a condensate purification system facility in which the retained water held in the suppression chamber in the nuclear power plant is transferred to the main condenser during the shutdown period of the nuclear power plant. It is characterized in that the suppression chamber is connected to the main condenser before the step of purifying the water.

According to the embodiment of the present invention, it is possible to efficiently carry out the purification treatment of the possessed water in the stopped nuclear power plant.

(I) A vertical sectional view of a nuclear power plant showing the state of storage of water held in a suspended nuclear power plant to which the water treatment method of the nuclear power plant according to the embodiment is applied. The system diagram explaining the treatment system of the possession water of FIG. A system diagram explaining the condensate purification system equipment and the water supply system equipment.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a vertical sectional view of a nuclear power plant showing the state of storage of retained water held in a stopped nuclear power plant to which the water treatment method of the nuclear power plant according to the embodiment is applied. The nuclear power plant 10 shown in FIG. 1 includes a reactor building 11, a turbine building 12, a condensate storage facility 13, and a waste treatment facility 14, and has a core (not shown) in the reactor building 11. A reactor storage vessel 16 for accommodating a reactor pressure vessel 15 is arranged. The condensate storage facility 13 and the waste treatment facility 14 are both facilities provided outside the reactor building 11 and the turbine building 12.

In addition to the reactor containment vessel 16, the reactor building 11 is provided with a reactor well 17, a spent fuel storage pool 18, a suppression chamber 19, and the like. By accommodating the reactor pressure vessel 15, the reactor containment vessel 16 prevents the leakage of radioactivity in the event of an accident as a primary containment facility. The reactor well 17 is a space above the reactor pressure vessel 15, and this space is filled with water during underwater work such as fuel removal. The spent fuel storage pool 18 stores the spent fuel while cooling it with cooling water. The suppression chamber 19 stores cooling water for cooling the core in the event of an accident. The reactor building 11 is a reinforced concrete structure and also functions as a secondary storage facility for preventing leakage of radioactive materials in the event of an accident.

In the turbine building 12, the turbine 21 and the generator (not shown) are arranged inside, and the main condenser 22 is arranged directly under the turbine 21. Further, the turbine building 12 is provided with a condensate purification system facility 23 (FIG. 2) including a main condenser 22. The turbine building 12 is a reinforced concrete structure similar to the reactor building 11, and functions to prevent leakage of radioactive materials in the event of an accident.

As shown in FIG. 2, the condensate purification system equipment 23 has a main condensate 22, a condensate pump 25, a filtration device 26, a desalination device 27, a circulation pump 28, and a main condensate in the condensate recirculation line 24. 22 are sequentially arranged and configured. The steam that worked in the turbine 21 is condensed by the main condenser 22 to be condensate, and the condensate purification system equipment 23 purifies the condensate. That is, while the condensate in the main condenser 22 circulates and flows through the condensate recirculation line 24 due to the operation of the condensate pump 25 and the circulation pump 28, impurities such as clads in the condensate and unnecessary ionic components are used. Is removed by the filtration device 26 and the condenser 27. If the capacity of the condensate pump 25 is sufficiently large, the circulation pump 28 may be omitted.

Further, a drainage pipe 29 provided with a drainage valve 30 is connected to the condensate recirculation line 24 in the condensate purification system equipment 23 downstream of the desalination device 27 and upstream of the circulation pump 28. The drainage pipe 29 is connected to the waste treatment facility 14 described in detail later, or is opened to the environment such as the sea.

The condensate storage facility 13 is installed outside the reactor building 11 and outside the turbine building 12, and is connected to the main condenser 22 inside the turbine building 12 by using the first connection pipe 31. Further, the condensate storage facility 13 is connected to the reactor well 17 in the reactor building 11 by using the second connection pipe 32, and the spent fuel storage pool in the reactor building 11 is connected by using the third connection pipe 33. It is connected to 18. During normal operation, the condensate storage facility 13 temporarily stores the condensate purified by the condensate purification system facility 23 via the first connection pipe 31, and then stores it at a required location, for example, the first connection pipe 31. Water is supplied to the main condenser 22 via the second connecting pipe 32, to the reactor well 17 via the second connecting pipe 32, and to the spent fuel storage pool 18 via the third connecting pipe 33.

The waste treatment facility 14 shown in FIG. 1 is a facility for treating liquid or solid waste generated in the reactor building 11 and the turbine building 12, and is installed outside the reactor building 11 and outside the turbine building 12. The liquid such as water treated by the waste treatment facility 14 is released to the environment such as the sea. The waste treatment facility 14 is also in operation during normal operation of the nuclear power plant 10. The amount of water to be treated by the waste treatment facility 14 during normal operation of the nuclear power plant 10 is a small amount of the retained water held in the nuclear power plant 10 and accumulated, so that the retained water is per unit time. The waste treatment facility 14 having a small treatment capacity is used for sufficient purification treatment.

On the other hand, for example, in the nuclear power plant 10 that has been shut down for a relatively long period of several months to several years, or in the nuclear power plant 10 before the decommissioning, the reactor well 17 in the reactor building 11 and the spent fuel are used. A large amount of water W Exists. Although it depends on the scale of the nuclear power plant 10, the water holding W in the reactor power plant 10 is assumed to be 9000 tons, for example, and the breakdown is 2000 tons in the reactor well 17 and 2000 tons in the spent fuel storage pool 18. The suppression chamber 19 has 2000 tons, the condensate purification system equipment 23 has 1000 tons, and the condensate storage equipment 13 has 2000 tons. In the decommissioning of the nuclear power plant 10 and the preparation for restarting, it is necessary to efficiently purify the above-mentioned large amount of retained water W in order to shorten the construction period.

If this large amount of retained water W is purified by the existing waste treatment facility 14, the treatment capacity of the waste treatment facility 14 per unit time is usually about 10 to 20 tons, so that the retained water W is purified. It takes a long time. Therefore, since the dismantling work and the work for restarting are performed after the purification treatment of the retained water W, the construction period for decommissioning the nuclear power plant 10 and preparing for restarting may be prolonged. Further, depending on the impurity content of the retained water W, a large load is applied to the waste treatment facility 14, which requires frequent maintenance, and the purification treatment of the retained water W may take a longer period of time.

In the water treatment method of the nuclear power plant in the present embodiment, a large amount of water W held in the nuclear power plant 10 during the outage period is used by using the condensate purification system facility 23 having a treatment capacity of about 1000 tons per unit time. It purifies a large amount in a short time, and has a first transfer step, a purification step, and a second transfer step. Further, before the first transfer step, there is a connection step as a water treatment preparation method for the nuclear power plant.

As shown in FIG. 2, the connection step is a step of connecting the suppression chamber 19 in the reactor building 11 to the main condenser 22 in the turbine building 12 by using the fourth connection pipe 34. In this connection step, as described later, the retained water W held in the suppression chamber 19 in the first transfer step is transferred to the main condenser 22, and the transferred retained water W is transferred to the condensate purification system in the purification step. It is carried out before purification by the equipment 23.

In the first transfer step, the retained water W held in at least one of the reactor well 17, the spent fuel storage pool 18, the suppression chamber 19, and the condensate storage facility 13 during the shutdown period of the nuclear power plant 10 is stored. This is the process of transferring to the main condenser 22. In the present embodiment, in the first transfer step, the retained water W held in the reactor well 17, the spent fuel storage pool 18, the suppression chamber 19, and the condensate storage facility 13 is used as the main condenser in the turbine building 12. Transfer to 22.

That is, in this first transfer step, the retained water W held in the reactor well 17 was transferred to the condensate storage facility 13 using the existing second connecting pipe 32 and held in the spent fuel storage pool 18. The retained water W is transferred to the condensate storage facility 13 using the existing third connection pipe 33, and the retained water W in the condensate storage facility 13 and the retained water W transferred to the condensate storage facility 13 are already installed. Transfer to the main condenser 22 using the first connection pipe 31 of the above. Further, in this first transfer step, the retained water W held in the suppression chamber 19 is directly transferred to the main condenser 22 by using the fourth connection pipe 34 newly installed in the above-mentioned connection step.

The purification step is a step of purifying the retained water W transferred to the main condenser 22 in the first transfer step by the condensate purification system equipment 23 in the turbine building 12. That is, while the retained water W transferred to the main condenser 22 circulates in the condensate recirculation line 24 by the operation of the condensate pump 25 and the circulation pump 28, the clad in the retained water W and the like are formed. The impurities are removed and purified by the filtering device 26 and the desalting device 27.

The second transfer step is a step of transferring the retained water W purified in the purification step to the outside of the turbine building 12 when the drain valve 30 is opened by using the drain pipe 29. The transfer destination of the purified retained water W in this second transfer step is the waste treatment facility 14. The possessed water W is component-measured and dosimetrically measured by the waste treatment facility 14, purified as necessary, released to the environment outside the nuclear power plant, or stored in a container or the like. If the retained water w is sufficiently purified in the purification process, it may be released to the environment outside the nuclear power plant or stored in a container or the like without going through the waste treatment facility 14. You may.

Since it is configured as described above, according to the present embodiment, the following effects (1) to (4) are obtained.
(1) The retained water W held in the reactor well 17, the spent fuel storage pool 18, the suppression chamber 19, and the condensate storage facility 13 in the stopped nuclear power plant 10 is transferred to the main condenser 22. A large amount of retained water W transferred to the main condenser 22 is purified in a short time by the condensate purification system equipment 23 whose treatment capacity per unit time is larger than that of the waste treatment equipment 14. As a result, it is possible to efficiently carry out the purification treatment of the possessed water W at the stopped nuclear power plant 10.

(2) When the retained water W is transferred to the waste treatment facility 14 via the drainage pipe 29 after the purification process of the retained water W using the condensate purification system equipment 23, the possessed water W becomes the condensate purification system equipment. Since it is once purified by 23, the load on the waste treatment facility 14 can be reduced. For example, since maintenance such as filter replacement can be reduced in the waste treatment facility 14, the purification treatment of the retained water W by the waste treatment facility 14 can be efficiently performed in a short time. Therefore, since the dismantling work and the work for restarting can be started quickly, the construction period for the abolition device of the nuclear power plant 10 and the preparation for restarting can be shortened.

(3) When the retained water W purified by sufficiently removing impurities in the retained water W by the purification process using the condensate water purification system equipment 23 is discharged to the environment through the drainage pipe 29, nuclear power is used. It is possible to eliminate a large amount of retained water W in the power plant 10 in a short time. Therefore, since the dismantling work and the work for restarting can be started quickly, the construction period for the abolition device of the nuclear power plant 10 and the preparation for restarting can be shortened.

(4) When the water treatment method of the present embodiment is applied when the nuclear power plant 10 is decommissioned, the condensate water purification system equipment 23 used in the purification process is the equipment to be dismantled. Therefore, since it is not necessary to newly introduce a treatment facility for purifying the retained water W in the nuclear power plant 10, the retained water W in the nuclear power plant 10 can be rationally treated.

Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention, and the replacements and changes thereof can be made. , It is included in the scope and gist of the invention, and is also included in the scope of the invention described in the claims and the equivalent scope thereof.

For example, before the first transfer step, a step of connecting the reactor well 17 to the main condenser 22 by the fifth connecting pipe 35 may be provided. In this case, in the first transfer step, the retained water W in the reactor well 17 is transferred to the main condenser 22 through the fifth connecting pipe 35 without passing through the condensate storage facility 13.
Further, before the first transfer step, a step of connecting the spent fuel storage pool 18 to the main condenser 22 by the sixth connecting pipe 36 may be provided. In this case, in the first transfer step, the retained water W in the spent fuel storage pool 18 is transferred to the main condenser 22 through the sixth connecting pipe 36 without passing through the condensate storage facility 13.

Further, in the purification step, when the retained water W is circulated and purified by the condensate purification system equipment 23, the water supply system equipment 45 may be used together. FIG. 3 is a system diagram illustrating the condensate water purification system equipment 23 and the water supply system equipment 45. The feed water system equipment 45 used here includes feed water heaters 41 and 43, a pump 42, and a water supply recirculation line 44 connecting them. The feed water recirculation line 44 is a pipe branched from the condensate recirculation line 24 downstream of the desalination device 27, and the feed water heater 41, the pump 42, and the feed water heater 43 are connected in order, and the main condenser 22 is connected. Connect to. In addition, there is a line that partially branches from the downstream of the feed water heater 43 and connects to the reactor.

When the holding water W is circulated and purified by the condensate purification system equipment 23, by using the water supply system equipment 45 together, more holding water W can be held on the rear side of the main condenser 22. .. Therefore, more retained water can be withdrawn from at least one of the reactor well 17, fuel storage pool 18, suppression chamber 19, and condensate storage facility 13, and the reactor well 17, fuel storage pool 18, suppression. Work on decommissioning and restart preparation in at least one of the chamber 19 and the condensate storage facility 13 can be started earlier.

10 ... Nuclear power plant, 11 ... Reactor building, 12 ... Turbine building, 13 ... Condensate storage equipment, 14 ... Waste treatment equipment, 15 ... Reactor pressure vessel, 16 ... Reactor containment vessel, 17 ... Reactor well , 18 ... Spent fuel storage pool (fuel storage pool), 19 ... Suppression chamber, 21 ... Turbine, 22 ... Main water purifier, 23 ... Restoration purification system equipment, 24 ... Restoration recirculation line, 25 ... Restoration Pump, 26 ... Filtering device, 27 ... Desalting device, 28 ... Circulation pump, 29 ... Drainage pipe, 30 ... Drain valve, 31 ... First connection pipe, 32 ... Second connection pipe, 33 ... Third connection pipe, 34 ... 4th connection pipe, 35 ... 5th connection pipe, 36 ... 6th connection pipe, W ... Owned water, 41 ... Water supply heater, 42 ... Pump, 43 ... Water supply heater, 44 ... Water supply recirculation line, 45 ... Water supply system equipment

Claims (6)

It is a water treatment method of a nuclear power plant that treats the water owned in the nuclear power plant during the shutdown period of the nuclear power plant.
The first transfer step of transferring the retained water held in at least one of the reactor well, the fuel storage pool, the suppression chamber and the condensate storage facility in the nuclear power plant to the main condenser in the turbine building.
A purification process that purifies the retained water transferred to the main condenser with the condensate purification system equipment inside the turbine building.
It has a second transfer step of transferring the retained water purified in the purification step to the outside of the turbine building.
The first transfer step is a water treatment method for a nuclear power plant, which comprises transferring the retained water held in the reactor well to the main condenser via the condensate storage facility . It is a water treatment method of a nuclear power plant that treats the water owned in the nuclear power plant during the shutdown period of the nuclear power plant.
The first transfer step of transferring the retained water held in at least one of the reactor well, the fuel storage pool, the suppression chamber and the condensate storage facility in the nuclear power plant to the main condenser in the turbine building.
A purification process that purifies the retained water transferred to the main condenser with the condensate purification system equipment inside the turbine building.
It has a second transfer step of transferring the retained water purified in the purification step to the outside of the turbine building.
The first transfer step is a water treatment method for a nuclear power plant, which comprises transferring the retained water held in the fuel storage pool to the main condenser via the condensate storage facility . It is a water treatment method of a nuclear power plant that treats the water owned in the nuclear power plant during the shutdown period of the nuclear power plant.
The first transfer step of transferring the retained water held in at least one of the reactor well, the fuel storage pool, the suppression chamber and the condensate storage facility in the nuclear power plant to the main condenser in the turbine building.
A purification process that purifies the retained water transferred to the main condenser with the condensate purification system equipment inside the turbine building.
It has a second transfer step of transferring the retained water purified in the purification step to the outside of the turbine building.
The first transfer step is a water treatment method for a nuclear power plant, characterized in that the retained water held in the suppression chamber is transferred to the main condenser without passing through the condensate storage facility . The water treatment method for a nuclear power plant according to any one of claims 1 to 3 , wherein the destination of the purified retained water in the second transfer step is a waste treatment facility or an environment. The water treatment method for a nuclear power plant according to any one of claims 1 to 4 , wherein in the purification step, a water supply recirculation line of the water supply system equipment is used in combination with the water supply purification system equipment. During the shutdown period of the nuclear power plant, the suppression chamber is restored to the main state before the process of transferring the retained water held in the suppression chamber in the nuclear power plant to the main condenser and purifying it by the condensate purification system equipment. A method for preparing water for a nuclear power plant, which is characterized by connecting to a condenser.

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