JPS63259499A - Filtering desalting device for nuclear power plant - 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] [Object of the Invention] (Industrial Field of Application) The present invention relates to a condensate filtration desalination device for a nuclear power plant, and in particular to a nuclear power plant capable of appropriately controlling the crud iron removal rate. Concerning condensate filtration and desalination equipment.

(Prior art) Figure 6 shows a schematic system diagram of a nuclear power plant. In FIG. 6, main steam generated from primary water in a reactor pressure vessel 21 is led to a turbine 22, and after driving the turbine 22, is led to a condenser 23 and becomes condensed water. This condensate is transported by a low-pressure condensate pump 24 to a condensate purification system consisting of a condensate, water filtration and desalination device 25, and a condensate demineralization device 26. In this condensate purification system, clad iron that is generated due to corrosion of plant constituent materials and mixed into the primary water is removed. This cladding iron is generally formed from particulate metal impurities.

Here, cladding refers to insoluble solid content (all components), and cladding iron refers to only the iron content of the insoluble solid content.

Thereafter, the condensate is transported by the high pressure condensate pump 27 to the feed water heater 28, where it is heated and transferred to the reactor pressure vessel 21 as feed water by the feed water pump 29.
It becomes 0.

A portion of the reactor water 30 is transferred by the reactor water purification pump 36 to the reactor water purification system filtration desalination device 34 and purified. In addition, the reactor pressure vessel 21 is equipped with a fuel pool cooling purification system filtration desalination device i! 235 is connected. Due to these, the impurity concentration of the reactor water 30 becomes approximately constant in a stable state of the plant.

This nuclear power plant is provided with a condensate filtration and desalination device 25, a reactor water purification system filtration and desalination device 34, and a fuel pool cooling and purification system filtration and desalination device 35 as filtration and desalination devices. Among these, the condensate filtration and demineralization device 25 includes a plurality of condensate filters 32 arranged in parallel, and further includes a bypass valve 33.

The condensate filtration device 25 will be further explained in detail in FIG.

The powder resin slurry created from the powder cation resin and the powder anion resin in the slurry creation tank 9 is transferred to the ejector 10.
The water is sucked up and precoated onto the element 8 installed in the condensate filter 2 by the precoat pump 11. Element 8 is a fine-mesh, single-layer stainless wire mesh, the outer surface of which is pre-coated with powdered resin.

Condensate containing clad iron is transferred to condensate filter 2 from condensate population 6.
The cladding iron is removed by passing through the element 8 containing the precoat layer, and then the residual water flows out from the condensate lower.

As the filtration mechanism in this condensate filter 2225, a model of the filtration mechanism related to differential pressure increase characteristics has been considered. FIG. 8 is an enlarged view of an element having a precoat layer, and FIG. 9 is a diagram showing a conventional filtration mechanism, showing the state of section A in FIG. 8.

As shown in FIGS. 8 and 9, the filtration mechanism has conventionally been considered only based on differential pressure characteristics.

In a filtration mechanism that is considered only based on differential pressure characteristics, for example, in Fig. 7, the condensate cladding iron concentration ■ is 1 opppb, while the outlet cladding iron concentration ■ may be IPPb at a certain time, or at a certain time. It was not possible to elucidate the phenomenon in which the outlet cladding iron concentration ■' was 3PPb, and the countermeasures were also unclear.

On the other hand, in order to lower the radioactivity level of the reactor water 30, simply reducing the amount of clad iron brought into the reactor water 30 is not effective; it is necessary to mix an appropriate amount of clad iron into the reactor water 30. . For this reason as well, it is necessary to appropriately and accurately control the amount of cladding iron at the outlet of the condensate filtration and desalination device 25.

However, in the conventional condensate filtration and desalination apparatus 25, slurry preparation conditions are uniform, and the outlet cladding iron concentration cannot be appropriately and accurately controlled.

In addition, in order to control the amount of crud iron brought into the reactor water 30, it is necessary to control the crud iron concentration at the outlet of the reactor water purification system filtration desalination device 34 and the fuel pool cooling purification system filtration demineralization device 35. Although necessary, condensate filtration and desalination equipment 25
Similarly, the slurry preparation conditions were uniform, and the outlet cladding iron concentration could not be controlled.

The present invention has been made in consideration of these points, and is a filtration desalination system for nuclear power plants that can appropriately control the outlet clad iron concentration of the filtration desalination equipment installed at nuclear power plants. The purpose is to provide equipment.

[Structure of the invention]

(Means for solving the problem of m points) The present invention precoats a powder resin slurry made from a powder cation resin and a powder anion resin in a slurry preparation tank onto an element in a filter, and then returns the powder resin slurry into the filter. A filtration desalination device for a nuclear power plant configured to remove clad iron through water, the slurry preparation tank being provided with an automatic charging device for appropriately controlling the amount of powdered cation resin and powdered anion resin, and further comprising: Install an agitator driven by an automatic transmission in the production tank,
A feature of this automatic transmission is that an automatic control device for controlling the stirring rotation speed and stirring time is connected to this automatic transmission.

(Function) The automatic dosing device changes the mixing ratio of powdered cation resin and powdered anionic resin, and the automatic control device changes the rotational speed and stirring time of the stirrer driven by the automatic transmission, thereby precoating the element. Conditions can be changed to control the outlet cladding iron concentration of the salt filtration device.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIGS. 1 to 5 are diagrams showing an embodiment of a filtration and desalination apparatus for a nuclear power plant according to the present invention, which is used as a condensate filtration and desalination apparatus for a nuclear power plant.

In FIG. 1, the condensate filtration and desalination apparatus 1 is configured to transfer a powder slurry made from a powder cation resin 15 and a powder anion resin 16 in a slurry production tank 9 to an ejector 10.
The condensate is sucked up by the pre-coat pump 11 and pre-coated onto the element 8 installed in the condensate filter 2, and the condensate is allowed to flow into the condensate filter 2 from the condensate inlet 6 to remove the clad iron. After that, it is configured to flow out from the rear water outlet lower.

Powder cation resin 15 and powder anion resin 16 are:
Cation tank 15a and anion tank 1, respectively.
The amount of the powdered cation resin 15 and the powdered anion resin 16 into the slurry preparation tank 9 is controlled as appropriate by the amount controller 17. The cation tank 15a, the anion tank 16a, and the amount controller 17 constitute an automatic feeding device.

Further, an agitator 12 driven by an automatic transmission 13 is installed in the slurry preparation tank 9, and this automatic transmission 13
Automatic control device 1 that controls stirring rotation speed and stirring time
4 are connected.

Next, the operation of this embodiment having such a configuration will be explained.

First, the slurry preparation tank 9 is filled with pure water to a specified level, and a specified amount of powdered anion resin 16 is put into the slurry preparation tank 9. In this case, the input amount controller 17 opens and closes the outlet of the anion tank 16a to control the input amount of the powdered anion resin 16. Next, the inside of the slurry preparation tank 9 is stirred by the stirrer 12, and the powdered cationic resin 1 is stirred.
Similarly to the powdered anion resin 16, a predetermined amount of the powdered anion resin 5 is charged into the slurry preparation tank 9 by the input amount controller 17.

In this way, the input amount controller 17 can automatically control the input amounts and mixing ratio of the powdered cation resin 15 and the powdered anion resin 16.

Further, the automatic control device 14 can automatically control the rotation speed and stirring time of the agitator 12 driven by the automatic transmission 13.

When this condensate filtration and desalination equipment was used, the following results were found regarding the outlet cladding iron concentration and the filtration mechanism.

First, regarding the filtration mechanism of condensate filtration and desalination equipment,
A model of filtration mechanism for outlet cladding iron concentration and differential pressure characteristics was found. This is shown in FIG.

・In other words, in Figure 2, the saturation mechanism can be assumed to be electrochemical adsorption - saturation 6 pure volume filtration - saturation - surface filtration - saturation, and the change in outlet cladding iron concentration related to the increase in differential pressure can be explained. I understand.

An example of this performance is shown in Figure 3.

Further, this change in the outlet cladding iron concentration is classified into 3FIf patterns as shown in FIG. It was found that in order to control the outlet clad iron concentration, it is necessary to understand the mixing ratio of the powdered resin slurry (C-powder cation resin ffi/A-powder anion resin amount) and the sedimentation characteristics of the powder resin floc. Ta. The sedimentation properties of powdered resin flocs are generally defined as V■ the slurry sedimentation volume after a certain period of time (approximately 15-20 minutes). - v/ divided by the initial slurry volume
vo, and this V/Vo can be changed by changing the stirring time and rotation speed of the stirrer for any mixing ratio.

FIG. 5 shows an example of the relationship between the average outlet clad iron concentration of the condensate filter 2 and the number of operating days using the mixing ratio and v/vo as parameters. For example, if you want the average outlet clad iron concentration of the condensate filter 2 to be Q, 8PPb, the mixing ratio C/A-
6/IV/V, Φ0°5 is sufficient. In that case, the number of operation days will be approximately 29 days.

In Fig. 5, the white lower row () indicates a predetermined V/V value, and the upper row shows the slurry stirring time until reaching that vZVo value, and the number of rotations of the stirrer 12 is increased or the area of the stirring blade is increased. By doing so, the stirring time can be shortened.

When a predetermined v/vo value is reached, the automatic controller 14 causes the automatic transmission 13 to stop driving the agitator 12 .

By changing the mixing ratio of the powder cation resin and the powder anion resin in this way, and changing the rotation speed of the stirrer 12 and the area of the stirring blades to change the v/vo value and change the slurry preparation conditions, the condensate filter It is possible to appropriately control the outlet cladding iron concentration of No. 2 (that is, the outlet cladding iron concentration of the condensate filtration and desalination device 1). In addition, condensate filtration desalination equipment 1
The change curve of outlet cladding iron concentration can also be controlled.

As described above, according to the present embodiment, the outlet cladding iron concentration of the condensate filtration and desalination apparatus 1 can be easily controlled, so even if the inlet water quality of the condensate filtration and desalination apparatus 1 changes, the outlet cladding concentration can be easily controlled. can be quickly and easily controlled. Also,
Since the cladding iron concentration at the outlet of the condensate filtration and desalination equipment 1 can be controlled as necessary, it is easy to control the amount of cladding iron brought into the reactor water, reducing the radioactivity level in the nuclear power plant. It is possible to reduce the radiation dose for people exposed to radiation.

In addition, in this embodiment, an example in which the filtration and desalination apparatus according to the present invention is applied is shown, but the present invention is not limited to this, and the filtration and desalination apparatus of the present invention can be applied to a reactor water purification system filtration and desalination apparatus or a fuel pool cooling purification system filtration. It can also be applied to desalination equipment.

〔Effect of the invention〕

According to the present invention, the cladding iron concentration at the outlet of the filtration and desalination apparatus can be easily controlled as necessary. Therefore, it becomes easy to control the amount of cladding iron brought into the reactor water, and it is possible to reduce the radioactivity level in the nuclear power plant and reduce the radiation exposure of workers.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a condensate filtration desalination device which is an embodiment of the filtration desalination device according to the present invention, and Fig. 2 shows the filtration mechanism of the change in the outlet cladding iron concentration of the condensate filtration desalination device. Figure 3 is a diagram showing outlet cladding iron concentration and differential pressure characteristics,
Figure 4 is a diagram showing the relationship between slurry creation conditions and outlet cladding iron concentration, Figure 5 is a diagram showing the relationship between outlet cladding iron concentration and number of operating days with resin mixing ratio and v/vo as parameters,
FIG. 6 is a schematic diagram of a nuclear power plant, FIG. 7 is a diagram showing a conventional condensate filtration desalination device, and FIG. 8 is an enlarged view of an element having a precoat layer of a conventional condensate filtration desalination device. 9th
The figure shows the filtration mechanism of a conventional condensate filtration and desalination device. 1... Condensate filtration desalination device, 2... Condensate filter, 8...
...Element, 9...Slurry creation tank, 12...
- Stirrer, 13... Automatic transmission, 14... Automatic control device, 15... Powdered cation resin, 15a... Cation tank, 16... Powdered anion resin, 16a...
-Anion tank, 17... input amount controller. Applicant's representative: Mr. Sato +0 20 30 40. It can be concluded that the number of days for cuttings, the number of days for cuttings, the number of days for cuttings, the mechanism of filtration, electrochemical feeding - fi left saturation - class volume overflow - @Tomorowa - WIm filtration - same left saturation. Filtration mechanism of outlet clad iron concentration change Figure 2 Number of days for cutting (days) Figure 3 Number of days for cutting Number of days for cutting (
o) (b) Number of operating days (days) Pre-coat layer Figure 8-11iJ! F Lifespan Conventional filtration mechanism

Claims (1)

[Claims] A nuclear power plant filtration system in which a powdered resin slurry made from powdered cation resin and powdered anionic resin is precoated on an element in a filter in a slurry preparation tank, and condensate is passed through the filter to remove crud iron. In the desalting equipment, the slurry making tank is provided with an automatic feeding device that appropriately controls the amounts of the powdered cation resin and powdered anionic resin, and the slurry making tank is further provided with an agitator driven by an automatic transmission. A filtration desalination device for a nuclear power plant, characterized in that an automatic control device for controlling stirring rotation speed and stirring time is connected to a transmission.