JPH0577280B2 - - Google Patents

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 particularly 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 filtration and demineralization device 25 and a condensate demineralization device 26 . In this condensate purification system, crud iron that is generated due to corrosion of plant constituent materials and mixed into the primary water is removed. This clad iron is generally formed from particulate metal impurities.

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

Thereafter, the condensate is conveyed to the feedwater heater 28 by the high-pressure condensate pump 27, heated there, and transferred as feedwater to the reactor pressure vessel 21 by the feedwater pump 29 to become reactor water 30.

A part of the reactor water 30 is supplied to the reactor water purification pump 3
6, the water is transferred to the reactor water purification system filtration desalination device 34 and purified. Further, a fuel pool cooling purification system filtration desalination device 35 is connected to the reactor pressure vessel 21 . 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.

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

Condensate containing crud iron flows into the condensate filter 2 from the condensate inlet 6, passes through an element 8 having a precoat layer to remove the crud iron, and then the condensate flows out from the condensate outlet 7. .

As the filtration mechanism in this condensate filtration device 25, a model of 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.
The state of part A in the figure is shown.

As shown in FIGS. 8 and 9, the filtration mechanism has conventionally been considered only based on differential pressure characteristics.
In a filtration mechanism considered only based on differential pressure characteristics, for example, in Figure 7, the condensate clad iron concentration is 10 PPb, while the outlet clad iron concentration is 1 PPb at a certain time, and at another time. It was not possible to elucidate the phenomenon in which the outlet clad iron concentration was around 3PPb, and the countermeasures were also unclear.

On the other hand, in order to reduce the radioactivity level of the reactor water 30, simply reducing the amount of crud iron brought into the reactor water 30 is not effective; it is necessary to mix an appropriate amount of crud iron into the reactor water 30. . For this purpose as well, it is necessary to appropriately and accurately control the amount of clad iron at the outlet of the condensate filtration and desalination device 25. However, the conventional condensate filtration and desalination equipment 25
However, slurry preparation conditions were uniform, and it was not possible to appropriately and accurately control the outlet clad iron concentration.

In addition, in order to control the amount of crud iron brought into the reactor 30, the reactor water purification system filtration desalination device 34
It is necessary to control the outlet clad iron concentration of the fuel pool cooling and purification system filtration desalination device 35, but as with the condensate filtration desalination device 25, slurry creation conditions are uniform, and the outlet clad iron concentration is controlled. I couldn't control it.

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

[Structure of the invention]

(Means for Solving the Problems) The present invention involves pre-coating 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 condensing water into the filter. The filtration desalination equipment for a nuclear power plant is configured to remove crud iron through the slurry preparation tank, and the slurry preparation tank is provided with an automatic feeding device for appropriately controlling the amount of powdered cation resin and powdered anion resin added. It is characterized in that a stirrer driven by an automatic transmission is installed in the tank, and an automatic control device that controls the stirring rotation speed and stirring time is connected to the automatic transmission.

(Function) By changing the mixing ratio of the powdered cation resin and powdered anion resin by the automatic feeding device, and by changing the rotation speed and stirring time of the stirrer driven by the automatic transmission by the automatic control device. Therefore, it is possible to control the iron concentration in the outlet cladding of the filtration/desalination device by changing the precoat state on the element.

(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 includes a powder cation resin 15 in a slurry preparation tank 9.
A powder slurry made from powder anion resin 16 is sucked up by an ejector 10, precoated onto an element 8 installed in a condensate filter 2 by a precoat pump 11, and the condensate is transferred to a condensate inlet 6.
The condensate is allowed to flow into the condensate filter 2 to remove crud iron, and then flows out from the ascites outlet 7.

The powder cation resin 15 and the powder anion resin 16 are temporarily stored in a cation tank 15a and an anion tank 16a, respectively, and are supplied to the slurry preparation tank 9 by the input amount controller 17.
The amount of input is controlled appropriately. The cation tank 15a, the anion tank 16a, and the amount controller 17 constitute an automatic feeding device.

In addition, an automatic transmission 1 is installed in the slurry preparation tank 9.
3 is installed, and an automatic control device 14 that controls the stirring rotation speed and stirring time is connected to this automatic transmission 13.

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 making tank 9 is stirred by the stirrer 12, and a prescribed amount of the powdered cationic resin 15 and the powdered anionic resin 16 are put into the slurry making tank 9 by the 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 transmission 13 is controlled by the automatic control device 14.
The rotation speed and stirring time of the stirrer 12 driven by the stirrer 12 can be automatically controlled.

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

First, regarding the filtration mechanism of the condensate filtration and desalination equipment, a model of the filtration mechanism with respect to outlet clad iron concentration and differential pressure characteristics was found. This is shown in FIG.

That is, in Figure 2, the filtration mechanism can be assumed to be electrochemical adsorption → saturation → pure volume filtration → saturation → surface filtration → saturation, and the change in outlet clad iron concentration can be explained in relation to the increase in differential pressure. I understand.

An example of this performance is shown in Figure 3.

In addition, this change in the outlet clad iron concentration is due to the fourth
As shown in the figure, it is classified into three types of patterns. In order to control the outlet clad iron concentration, it was found that it is necessary to understand the mixing ratio of the powdered resin slurry (C = amount of powdered cation resin / A = amount of powdered anionic resin) and the sedimentation characteristics of the powdered resin floc. Ta. The sedimentation characteristics of powdered resin flocs can generally be understood as V/ _V0 , where V=slurry sedimentation volume after a certain time (approximately 15 to 20 minutes) divided by _V0 =initial slurry volume. Moreover, this V/V ₀ 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/V ₀ as parameters. For example, condensate filter 2
If you want to set the average outlet clad iron concentration to 0.8PPb, the mixing ratio C/A=6/1V/V ₀ ≒0.5 should be used. In that case, the number of operating days will be approximately 29 days.

In Figure 5, the lower part in parentheses indicates the predetermined V/V ₀
The upper row shows the slurry stirring time until reaching the V/V ₀ value, and the stirring time can be shortened by increasing the rotation speed of the stirrer 12 or increasing the area of the stirring blades. can. When the predetermined V/V ₀ value is reached, the automatic controller 14 stops the agitator 12 from driving the automatic transmission 13 .

In this way, by changing the mixing ratio of the powdered cation resin and powdered anionic resin, and also by changing the rotation speed of the stirrer 12 and the area of the stirring blades, changing the V/V ₀ value and changing the slurry creation conditions, the condensate The clad iron concentration at the outlet of the filter 2 (that is, the clad iron concentration at the outlet of the condensate filtration and desalination apparatus 1) can be appropriately controlled. Moreover, the change curve of the clad iron concentration at the outlet of the condensate filtration and desalination apparatus 1 can also be controlled.

In this way, according to this embodiment, the outlet clad iron concentration of the condensate filtration and desalination apparatus 1 can be easily controlled, so even if the quality of the inlet water of the condensate filtration and desalination apparatus 1 changes, the outlet clad iron concentration can be controlled. can be quickly and easily controlled. In addition, the concentration of crud iron at the outlet of the condensate filtration and desalination equipment 1 can be controlled as necessary, making it easier to control the amount of crud iron brought into the reactor water, thereby reducing the radioactivity level at the nuclear power plant. Therefore, it is possible to reduce the radiation dose of workers.

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, it is possible to easily control the clad iron concentration at the outlet of the filtration and desalination equipment as required. Therefore, it becomes easy to control the amount of crud 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 drawings]

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 clad iron concentration at the outlet of the condensate filtration desalination device. Figure 3 is a diagram showing the outlet cladding iron concentration and differential pressure characteristics, Figure 4 is a diagram showing the relationship between slurry preparation conditions and outlet cladding iron concentration, and Figure 5 is a diagram showing the relationship between the slurry preparation conditions and the outlet cladding iron concentration.
The figure shows the relationship between the outlet clad iron concentration and the number of operating days, with the resin mixing ratio and V/V ₀ 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. FIG. 9 is a diagram showing the filtration mechanism of a conventional condensate filtration and desalination apparatus. 1... Condensate filtration desalination device, 2... Condensate filter,
8...Element, 9...Slurry creation tank, 1
2... Stirrer, 13... Automatic transmission, 14... Automatic control device, 15... Powder cation resin, 15a
... Cation tank, 16 ... Powdered anion resin, 16a ... Anion tank, 17 ... Input amount controller.

Claims (1)

[Claims] 1. A nuclear power plant configured to pre-coat an element in a filter with a powder resin slurry made from a powder cation resin and a powder anion resin in a slurry preparation tank, and pass condensate through the filter to remove crud iron. In the filtration desalination apparatus, the slurry creation tank is provided with an automatic charging device that appropriately controls the amount of powdered cation resin and powdered anion resin, and the slurry creation tank is further equipped 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 this automatic transmission.