JPS61265600A - Radioactive waste treating facility - 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] [Field of Application of the Invention] The present invention relates to radioactive waste treatment equipment of nuclear power plants, and in particular to the treatment of backwash waste generated from non-auxiliary filtration equipment for condensate purification systems. [Background of the Invention] In conventional boiling water nuclear power plants, the condensate purification system includes a condensate demineralizer loaded with granular ion exchange resin, or a powder demineralizer. A purification system that combines a precoat type filtration device using a filter aid such as ion exchange resin and a demineralizer is used.

Radioactive waste generated from conventional condensate purification system filtration equipment has been treated as follows using the treatment equipment shown in FIG. In other words, the condensate purification system powder resin precoat type filtration device 4 is controlled by the operating differential pressure, and when the specified differential pressure is reached, backwashing is automatically performed and the filtration of powdered ion exchange resin, etc. Backwash waste liquid containing auxiliary materials is generated. Crud components, mainly iron oxide, captured by the filtration device adhere to the powdered ion exchange resin, and are discharged from the filtration device together with the ion exchange resin during backwashing.

The backwash waste liquid generated in this way is once received in a backwash water receiving tank 6 installed at the bottom of the condensate purification system filtration device 4, and then transferred to a sedimentation separation tank 7. This sedimentation separation tank 7 sediments and separates the powdered ion exchange resin and solid contents such as chlorine and chlorine adhering to the resin from the backwash water, and also stores the solid contents such as the powdered ion exchange resin and chlorine and chlorine for a certain period of time. It has the function of attenuating radioactivity.

After the solid content is sedimented and separated in a sedimentation separation tank 7 using a ζ filter, the supernatant water is decanted and transferred to a liquid waste treatment facility 9.
After being treated in the same way as equipment drain, etc., it is collected into a condensate storage tank and reused within the power plant.

On the other hand, the solid content that has been sedimented and separated is stored for a certain period of time and attenuated, then transferred to the solidification equipment 8, packed in drums, and solidified. The above is a conventional method for treating backwash waste liquid from a condensate purification system filtration system.

However, in recent years, there have been plans to install non-auxiliary material type filtration devices in condensate purification systems in order to meet the demand for reducing waste generation and, by extension, equipment costs. Development is progressing diligently.

The non-auxiliary type filtration device mentioned above does not use filtering aids such as powdered ion exchange resin, so it does not generate secondary waste and eliminates the need for large-capacity sedimentation tanks that were previously required. There are benefits. However, the method for treating backwash waste generated from a non-auxiliary type filtration device has not yet been determined, and there are problems as described below.

In conventional powder resin pre-coat type filtration equipment, the backwash waste liquid contains crud and powdered ion exchange resin, and the crud adheres to the resin, making it relatively easy for the solid content in the waste liquid to settle and separate. Ta. However, non-aid type filtration devices do not use filtration aids such as ion exchange resins, and hollow fiber membrane filtration devices in particular have the advantage of being able to capture minute crud on the micron order due to their performance. The backwash waste liquid generated from this non-auxiliary material type filtration device is
Because there are no filter aids such as ion-exchange resins, and there are many ultra-fine particles on the micron order that are difficult to settle, the conventional sedimentation separation treatment method for backwash waste liquid is impractical. However, the lack of a well-established treatment method for backwash waste from non-auxiliary filtration devices is a major obstacle to the installation of non-auxiliary filtration devices.

FIG. 5 shows the sedimentation separation characteristics of backwash waste liquid when a non-auxiliary type (hollow fiber membrane type) filter is used in the condensate purification system. As can be understood from this figure, the iron concentration percentage [wt%] is 2.
At 0% or less, almost no sedimentation occurs.

Figure 6 shows the backwashing waste liquid after 24 hours of sedimentation separation.
The solid content particle size distribution in supernatant water is shown.

Since the conventional condensate purification system filtration device is used as the above-mentioned auxiliary material, the rational method for treating the backwash waste liquid is to perform sedimentation separation treatment of the solid content in a sedimentation separation tank. However, from the viewpoint of reducing waste generation and equipment operating costs, there is a trend toward adopting non-auxiliary material type filtration devices such as hollow fiber membrane type in condensate purification systems.

However, as shown in Figure 6, the hollow fiber membrane type filtration device is capable of capturing cracks and cracks on the order of microns or less due to its performance. Difficult to separate. However, it can be said that the sedimentation separation process in the conventional sedimentation separation tank is not suitable for the treatment of backwash waste liquid of a non-auxiliary type filtration device.

Actually, iron cladding (Fe203) with a particle size of 0.1 micron
Calculating the sedimentation rate using Stokes' theorem is as follows.

Calculation formula: Ut=g(ρ, -ρf)D2/18μUt: Terminal sedimentation velocity [saws/sec) g: Gravitational acceleration 980 ccm/s@a2)ρ3: Density of particles (Fe203) 5.2 Cg/as' ]ρf
: Density of fluid (water) 1 (g/cm' :) D: Particle size 0.1 [μ) = 10-5 (: particles] μ: Viscosity of fluid (water) I x 10-2 g/cn・sec (at C)
, calculating Nyoshi Ut is approximately 8X10-'IyfI/h
becomes.

In other words, it takes 12,500 hours to settle 1 meter of 0.1 micron iron cladding, and from this calculation, it can be said that it is unrealistic to perform sedimentation separation treatment for backwash waste liquid from a filtration device as a non-auxiliary material. .

Therefore, when carrying out sedimentation separation, it is possible to use a flocculant to promote coagulation and sedimentation of solids, but since such a flocculant is used, the amount of waste generated increases. Not suitable for processing objects.

[Purpose of the invention]

The purpose of the present invention is to provide a radioactive liquid waste treatment facility that:
In order to realize the use of non-auxiliary materials (rationalization) in condensate purification system filtration equipment, we developed a system that processes backwash waste generated from non-auxiliary filtration equipment without sedimentation and separation of solid content. It is about providing.

[Summary of the invention]

Kinei EA was developed to achieve the above objective based on the background described above, and is used in nuclear power generation equipment that uses a non-auxiliary m-filtration device in the condensate purification system. The backwash waste liquid is passed through a concentration processing device to be concentrated without undergoing sedimentation separation in a tank and solid content attenuation process, and only the concentrated waste liquid with a high solid content is solidified in a solidification equipment. This solves the above-mentioned problems.

[Embodiments of the invention]

The present invention will be specifically described below with reference to FIGS. 1 to 3.

In Fig. 1, the backwash waste generated from the non-auxiliary filter 10 of the condensate purification system is once received in the backwash water receiving tank 6, and when the concentration of crud is high, the crud is solidified without being sedimented and separated. It is transferred to equipment 8 and solidified into drums.

Moreover, when the concentration of crud content is relatively low, it is also possible to reduce the load on the solidification equipment 8 by concentrating the backwash water and reducing waste liquid.

Specifically, the backwash water is passed through a parallel flow furnace material filtration device such as a porous tube filter or a concentration processing device 11 such as an evaporative concentration device, and is concentrated to about 100 to 200 times, so that the solid matter is high. Only the concentrated waste liquid that has become concentrated is transferred to the solidification equipment 8,
This is a solidification process.

The permeated water (treated water) or distilled water from the concentration treatment device 11 is transferred to the liquid waste treatment facility 9, where it is once again subjected to filtration and desalination treatment to reduce the electrical conductivity to a specified value or less.
In principle, it shall be reused within the plant. In the concentration processing device 11, the crud content in the backwash waste liquid is concentrated, and the permeate water (treated water) in which the crud concentration has been sufficiently reduced is obtained.
Alternatively, distilled water can be desalinated and used as reused water.

The average bore diameter of the porous tube filter is 0.
Since it is 2 microns thick and uses parallel flow filtration, there is no risk of solid content in the backwash waste liquid entering the filter permeate side.

In summary, in the treatment equipment shown in Figure 1, the backwash waste liquid containing minute cracks and cracks is not subjected to sedimentation separation treatment, and when the solid content concentration in the backwash waste liquid is high, the waste liquid is directly processed or If the waste liquid is low, the waste liquid is passed through a concentration treatment device, concentrated, and then transferred to a solidification facility, thereby making it possible to use a non-auxiliary filter for condensate purification. .

A basic embodiment of a radioactive liquid waste treatment facility according to the present invention is shown in FIG. In the figure, reactor coolant is evaporated in a reactor 1, drives a turbine 2, and then becomes condensed in a condenser 3.A hollow fiber membrane type condensate filter 12 and a condensate desalination device are used. 5, it is purified and returned to the reactor 1. In this condensate purification system equipment, the condensate desalination device 5 uses a mixed bed demineralizer, and the used resin is temporarily stored and then solidified as in the conventional method. Since it is not directly related to the present invention, detailed explanation will be omitted here.

In this example, since the condensate filtration device uses a hollow fiber membrane that does not have an auxiliary material, the used powdered resin that was generated from the condensate filter is not generated and the cladding is removed. The contained backwash waste liquid becomes the target waste in the waste treatment facility. A major feature of this embodiment is that this backwash waste liquid is directly treated with a low conductivity waste liquid system or a high conductivity waste liquid system that has a porous tube filter 14, which is a parallel flow furnace material filtration device of a liquid waste treatment facility. It is a characteristic.

That is, when treating the backwash waste liquid of the condensate filter with a low conductivity waste liquid system, the following processing steps are taken. The backwash waste generated from the hollow fiber membrane type condensate filter 2 is once received in the condensate filter backwash receiving tank 6 and then transferred to the low conductivity waste liquid collection tank 13. Note that if the condensate can be directly transferred from the condensate filter to the collection tank 13, the installation of the backwash receiving tank 6 can be omitted. In the low conductivity waste liquid system, after being subjected to temporary treatment by the porous tube filter 14, the permeated water (treated water) is desalted by the demineralizer 15, and is basically recovered to the condensate storage tank 17. The backwash waste liquid is combined with other low-conductivity waste liquids and passed through the porous tube filter 14 to concentrate solid contents such as chlorine and carbon in the waste liquid.

In the Delus tube filter 14, the waste liquid circulates through the tube-shaped F material and passes through clear water, gradually increasing the concentration of solids in the circulating liquid and concentrating the waste liquid. becomes.

Here, the bore diameter of the porous tube filter 14 is 0.2 microns on average, and as mentioned above, there is almost no possibility that crud in the backwash waste liquid will enter the permeate side. good.

As described above, the concentrated waste liquid with a high solid content concentration is transferred to the concentrated waste liquid tank 23, where it is temporarily stored and then transferred to the solidification equipment 8 where it is assimilated.

On the other hand, when the backwash waste liquid from the hollow fiber membrane deaf condensate filter 12 is treated with a high conductivity waste liquid system, the following steps are taken. The backwash waste liquid generated from the hollow fiber model filter 12 is
The process of transferring to the high conductivity waste liquid collection tank 18 is the same as the case of transferring to the low conductivity waste liquid collection tank 13 described above. In the high-conductivity waste liquid system, after the concentrated distillation process by the evaporative concentrator 19, the distilled water is desalted by the demineralizer 20, and then collected into the condensate storage tank 17, or the water is discharged from the water outlet 22. released from the system. The backwash waste liquid is concentrated and distilled together with other high conductivity waste liquids in an evaporative concentrator 19, and the concentrated waste liquid is processed in the same manner as the concentrated liquid of the porous tube filter 14 described above.

The frequency of occurrence of backwash waste liquid from the hollow fiber membrane type condensate filter 12 is expected to be about once per year per tower, and the amount generated is small at about 10 m/pa, de, so low conductivity waste liquid system, No matter which high conductivity waste liquid system is used for treatment, there is no problem in terms of system and equipment capacity.

According to this embodiment, it is possible to treat backwash waste liquid from a non-auxiliary condensate filter using existing liquid waste treatment equipment without installing a dedicated treatment device. There is an economical advantage, and the load on the solidification equipment can be reduced because the backwash waste liquid from the condensate filter is not transferred directly to the solidification equipment, but is transferred to the concentration processing equipment after concentration. Effects such as this can be obtained.

As an applied embodiment of the present invention, in addition to the processing described above, a processing method as shown in FIG. 3 can be considered. In this application example, it is assumed that the condensate desalination device 5 is non-regenerating so that recycled waste liquid is not generated, and low conductivity waste liquid and high conductivity waste liquid are subjected to p-filtration and desalination treatment, and A major feature is that a hollow fiber membrane is used for the filtering device 26.

Therefore, even if the backwash waste generated from the hollow fiber membrane type condensate filter 12 is treated in the liquid waste treatment equipment, the crud in the backwash waste will be returned to the hollow fiber membrane dust v filter of the liquid waste treatment system. The problem now arises in the treatment of the backwash waste liquid of the hollow fiber membrane filtration device of the liquid waste treatment facility.

Therefore, in this application example, the hollow fiber membrane type condensate filter 12
The backwash waste liquid is not transferred to the liquid waste treatment system, but directly transferred to the solidification equipment 8.

However, in order to reduce the load on the solidification equipment, a small-capacity concentration processing device 24 (porous tube filter or evaporative concentration device, etc.) dedicated to backwash waste liquid treatment is installed, and the backwash waste liquid is concentrated and the concentrated liquid is solidified using the solidification equipment 8. Another option is to transfer the data to The permeated water (treated water) or distilled water from the concentration treatment device 24 is transferred to a collection tank 25 of the liquid waste treatment system, where it is subjected to filtration and desalination treatment. Further, the backwash waste liquid generated from the hollow fiber membrane type filtration device 26 of the liquid waste treatment system is also treated in the same manner as the backwash waste liquid from the condensate filter 12.

As described above, according to this application example, it is possible to simplify the liquid waste treatment equipment by collectively processing the low conductivity waste liquid system and the high conductivity waste liquid system, and a small By installing a volumetric concentration processing device, effects such as being able to reduce the load on the solidification equipment can be obtained.

In both the basic example and the applied example, when the backwash waste liquid is concentrated, the volume of the concentrated liquid to be solidified will be smaller than that of the backwash waste liquid. It becomes possible to temporarily store it in the storage tank at the foot of the foot. If you save it for a while, you can get the effect of attenuating radioactivity.

〔Effect of the invention〕

According to the present invention, the following effects can be obtained.

■ It is not necessary to install a large-capacity sedimentation separation layer for backwashing waste liquid treatment of condensate filters, which has the effect of reducing building volume and improving economic efficiency.

■ Since crud-containing backwash waste liquid is not treated by the condensation sedimentation method using coagulants, etc., it is effective in preventing an increase in the generation of waste (solid content).

■ It is possible to treat backwash waste liquid containing minute particles and particles.
By installing a non-auxiliary filter in the condensate purification system,
It is possible to reduce the amount of waste (used powder resin) generated.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram showing a radioactive waste treatment facility of the present invention, FIG. 2 is a schematic system diagram showing a basic embodiment of the present invention, and FIG. 3 is a schematic system diagram showing an applied example of the present invention. Figure 4 is a schematic system diagram showing conventional radioactive waste treatment equipment, Figure 5 is a sedimentation separation characteristic diagram of backwash waste liquid from a non-auxiliary condensate filter,
FIG. 6 is a solid content particle size distribution diagram in supernatant water after 24 hours of sedimentation and separation of backwash waste liquid from a non-auxiliary type condensate filter. 1... Nuclear reactor 2... Turbine 3...
Condenser 4... Powder resin pre-coated condensate filter 5... Condensate desalination device 6... Condensate filter backwash tank 7... Sedimentation separation tank 8... Solidification equipment 9.・・・
Liquid waste treatment equipment 10...Non-auxiliary material type condensate filter 11...Backwash waste liquid concentration processing device 12...Hollow fiber membrane type condensate filter 13...Low conductivity waste liquid system collection tank 14. ... Porous tube filter 15 ... Low conductivity waste liquid system desalination device 16 ... Low conductivity waste liquid system sample tank 17 ... Condensate storage tank 18 ... High conductivity waste liquid system collection tank 19...Evaporative concentration device 20...High conductivity waste liquid system desalination device 21...High conductivity waste liquid system sample tank 22...Water outlet 23...Concentrated waste liquid tank 24...Small capacity Concentration processing device 25...Liquid waste treatment system collection tank 26...Liquid waste treatment system hollow fiber M filter 27...Liquid waste treatment system desalination device 28...Liquid waste treatment system sample tank l: Hara, 4
-Length Ps Otsu:, 11&Furuzu reverse j Maruuke Tanks - Turbine 6:r! 7AL equipment, 5
:a rice S Wazurin Meishi Limited Express Rikibi, 5:a*, 1
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) nb571: Reverse 3 first, good 5 good can row J! Equipment Figure 2 Figure 3 Figure 4 Figure 5 Settling time (Hr)

Claims (1)

[Claims] 1. In nuclear power generation equipment that uses a non-auxiliary filtration device in the condensate purification system, backwash waste generated from the non-auxiliary filtration device is directly treated when the solid content concentration is high. Furthermore, when the solid content concentration is low, the radioactive waste treatment equipment is characterized in that water is passed through the concentration treatment equipment to perform concentration, and then transferred to the solidification treatment equipment for solidification treatment. 2. The radioactive waste treatment facility according to claim 1, wherein the concentration processing device is a parallel flow filter media filtration device using a porous tube filter. 3. The radioactive waste treatment facility according to claim 1, wherein the concentration processing device is an evaporative concentration device.