JPS60120298A - Regenerator for rein in condensate desalting instrument - 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 a regeneration method and regeneration system for L1 condensate desalination equipment, and particularly to a regeneration method and system suitable for reducing radioactive waste in nuclear power plants. The present invention relates to a playback system for carrying out the playback method described on the left.

[Background of the invention]

In order to smoothly operate nuclear power generation I9i and thermal power plants, etc., it is necessary to use highly reliable C1t as equipment for various devices. Similarly, in terms of water quality management for boiling water reactors, each S#
Strict management is carried out using purification equipment, but a large amount of radioactive waste is generated as a result of the operation of the purification equipment, amounting to approximately 50% of the amount generated from the entire plant.

Therefore, today it is possible to reduce waste generation from these purification systems at a lower cost.

Figure 1 shows an example of a system overview of a current boiling water reactor. Steam discharged from the reactor pressure vessel 1 passes through a high pressure turbine 2 and a low pressure turbine 3, and becomes condensed water in a condenser 4. Corrosion formation that occurs in the condenser 4, the extraction system 7 that connects the turbine 3 and the feed water heater 8, and the feed water heater 8, etc. (Ions and oxides of iron, cobalt, etc.) Wax, impurities in the condensate, etc. It is removed by a condensate purification system such as a p-filtration device 5 and a condensate desalination device 6. Thereafter, the water passes through the feed water heater 8 and returns to the reactor pressure vessel l. Note that the condenser is usually cooled by seawater or the like.

The cooling water systems of these reactors are contaminated with foreign substances such as nuclear fission products and corrosion products (crud) of the cooling water pipes, and when the concentration of these foreign substances increases, they can cause damage to the piping of the cooling water system and the surfaces of the fuel rods. A phenomenon occurs in which a cladding film is formed and radioactive fission products are occluded on its surface. As a result, this becomes a major obstacle when inspecting the pipes, hops, valves, etc. of the cooling water system. Further, if the crud adheres to the surface of the fuel rod, heat transfer between the fuel rod and the cooling water is inhibited and local heating occurs, which may lead to damage to the fuel rod.

Currently, for purification of cooling water for nuclear couplers (11 condensate P
(i) A condensate purification device that is a combination of a desalination device and a condensate desalination device, (2) A reactor purification device is used, but the capacity of the condensate purification device (1) that processes all condensate. is large.

Here, the condensate filtration device is made by powdering bead-shaped ion exchange resin and coating it on a nylon element, and is mainly used to remove crud generated upstream of the condensate system. It is installed in

In addition, the condensate desalination equipment is a mixed-bed desalination tower made of anion and cation exchange resins, and by passing condensate through this, the ionic components and crud in the condensate are ion-exchanged with the ion exchange resin layer. and filtration to purify the condensate.

The ionic components and cladding captured by the ion exchange resin are extracted from the condensate desalination equipment and regenerated separately in a regeneration tower. The regeneration method includes chemical regeneration of the ion exchange resin with acid and alkali, and physical cleaning of the ion exchange resin by backwashing, whereby the ion exchange resin is desorbed and discharged from the system.

FIG. 2 shows a regeneration system of the conventional mixed-bed desalination apparatus using the above-mentioned out-of-column regeneration method. The ion exchange resin with reduced desalination performance in the desalination device 6 is transferred to the A/exchange tower 9, where the ion exchange resin is converted into an anion exchange resin 11 according to the difference in specific gravity by the injected water 17 and air 18. and cation exchange resin 12. The separated anion exchange resin 9 is transferred to an ion exchange resin regeneration tower 13.

In the ion exchange resin regeneration tower IO, the cation exchange resin 12 is regenerated with sulfuric acid, and in the anion exchange resin regeneration tower 13, the anion exchange resin 9 is regenerated with caustic soda 15. The recycled resin is transferred to the resin mixing tower 16, where the cation exchange resin and the anion exchange resin are mixed, and then charged into the condensate demineralization tower 6 again, where the condensate 19 is treated and feed water 20 is obtained.

The amount of radioactive waste generated as a result of these regenerations amounts to about 20% of the amount generated in the entire plant, so the reduction effect on the waste generation side is significant.

Kirani, as a means of reducing the amount of recycled waste liquid, in the final treatment stage, the sulfuric acid used to regenerate the cation resin and the caustic soda used to regenerate the anion resin are neutralized and converted into sodium sulfate (mirabilite). Because of this, there are limits to volume reduction such as concentration treatment.

Therefore, as a fundamental measure to reduce the amount of waste, there is a problem in that it is necessary to improve the resin regeneration efficiency per recycled liquid tank and reduce the amount of recycled liquid by changing the recycling method.

[Purpose of the invention]

The present invention achieves a total improvement in regeneration efficiency per regenerated liquid by combining methods to improve the regeneration efficiency of ion exchange resins, which ultimately occurs through regeneration. The object of the present invention is to provide a regeneration method that achieves a reduction in the amount of radioactive waste; and an apparatus that can employ the regeneration method.

[Summary of the invention]

Ion exchange resins are regenerated by removing attached ions/ions (iron, copper, cobalt, nickel 7, etc. for cation resins, chlorine, sulfuric acid, etc. for anion resins) that are attached to the surface of the ion exchange resin by ion exchange reactions. , bicarbonate ions, etc.) with hydrogen ions/or hydroxyl ions/that are present in large amounts in the regenerating solution.

Furthermore, from the perspective of reducing the amount of radioactive waste, reusing the regenerating liquid that has been used for regeneration will lead to effective use of the regenerated chemicals, so we investigated the possibility of reuse.

As mentioned earlier, it is said that impurities attached to the surface of the ion exchange resin are eluted as a result of a competitive reaction with the regenerated resin 1, which is present in large quantities in the regenerated liquid. If the concentration of impurities present therein is extremely low compared to when the regenerant is used, it can be reused. In this case, it goes without saying that the amount of the regenerating chemical must be sufficient to fill the exchange capacity of the ion exchange resin to be regenerated.

In fact, water sampling and regeneration were repeated for about five years at a nuclear power plant, and Table 1 shows the impurity concentration If in the waste liquid from which the resin with the highest ion load and the impurity concentration in the recycled S liquid was considered to be crystalline. Make it.

From the measurement results shown in Table 1, the concentration of impurities in the conventional waste liquid that has been recycled once is about 1/1000 or less of the concentration of the regenerated chemical, so it can be ignored. Therefore, even if the recycled waste liquid is used again, there is almost no effect on the ion exchange resin regeneration efficiency.

This indicates that the recycled waste liquid obtained by regenerating the resin from the condensate demineralization tower used in the current boiling water type atomic cuffant can be sufficiently reused.

The main reason why it has not been reused so far is that the design was designed to allow for continued operation while regenerating the desalination tower resin even in the event of a seawater leak from the condenser heat exchanger. It had been.

Since it was believed that the recycled waste liquid at that time contained large amounts of chlorine and sodium ions, which are seawater components, reuse of the regenerant was not considered.

Today, however, technological improvements in the materials and maintenance of condenser heat exchangers have significantly reduced the possibility of seawater leaks, and it can be safely assumed that they rarely occur. ing. As a result, there is almost no possibility that chlorine, which is harmful to corrosion, will be contained in the recycled waste liquid.

On the other hand, as for improving the regeneration efficiency of the ion exchange resin, judging from the results of previous studies, it has been found that it can be achieved by increasing the concentration of chemicals in the regeneration solution or by slowing down the water flow rate of the regeneration solution. An example of these experimental results is shown in FIG.

FIG. 3 shows the integrated value of iron ions eluted from the cation exchange resin by the sulfuric acid regeneration solution. As a result, J:F) When the concentration of the regeneration chemical in the regeneration solution is doubled, the regeneration efficiency is improved.

However, from the point of view of reducing the amount of recycled waste materials, this method is difficult to implement in actual equipment because the amount of Glauber's salt ultimately generated as waste increases and the amount of chemicals used in the regenerating solution increases. It becomes an effect. Next, it can be seen that it is effective to improve the regeneration efficiency by slowing down the water flow rate of the regeneration liquid. 1 From the results shown in Figure 3, if the regenerating solution water flow rate is reduced to about 1/2, the amount of leached iron adhering to the ion exchange resin will more than double.

The water flow rate of the regenerating chemicals is □10 considering the case where there is a seawater leak and the case where there is no seawater leak.
It is necessary to adjust the tune from 1 cm/min to 1 crn/min.

[Embodiments of the invention]

Examples of the present invention will be shown below.

FIG. 4 is an example of a regeneration system for reusing recycled waste liquid. The regenerated liquid is transferred from the raw liquid storage tank 2 in a partially diluted state through the regenerated chemical transfer line 21 to the regenerated liquid tank 2.
2 and stores the amount necessary for one playback. After the regeneration tower is filled with resin sent from the resin transfer line/31, regeneration yt is injected from the chemical injection line/20, and the regenerated waste liquid is
Recovered Lie: /24J: Recovered in the regenerated liquid tank.

This palindromed recycled waste liquid is used in the next regeneration.

To dispose of the regenerated liquid, close the valve 26 and send the waste liquid recovery tuck through the transfer line 23 with the valve 25 activated.

Figure 5 shows the case where a dedicated D tank is installed to store recycled waste liquid to be reused. In the event of an emergency such as a leak, it is possible to improve the reproduction success rate and shorten the reproduction time.

Fig. 6 shows the case where the regeneration method is implemented to slow down the flow rate of the regeneration liquid, and the flow rate of the regeneration liquid injection life 2-1 is shown in Fig. 6. . In this case, since it is possible to measure the regeneration efficiency per regenerated sputum volume, the conventional regeneration efficiency can be maintained sufficiently even if the amount of regeneration liquid used is reduced.

Figure 7 shows the case where the flow rate of the regenerated liquid is slowed down and 29 collection basins are installed for the reused regenerated liquid in the same way as in Fig. 6.It is 7'C, and is used at all times in case of emergencies such as seawater leaks. It becomes possible to prepare a clean regeneration solution.

The radioactivity detector 28F shown in Figures 6 and 7
i. Detection of radiation in the regenerating liquid used repeatedly,
By understanding the concentration of impurities in the regenerated waste liquid, it is possible to determine when to replace the regenerated liquid with a new one. Since the radioactivity concentration and impurity ion concentration in the recycled wastewater differ depending on the quality of the condensate water of each plant, it is good to have a correlation between the radioactivity concentration and impurity ion concentration in advance. When the radioactivity detector 28 indicates that it is necessary to replace the regenerated liquid with a new one, the valve 26 is closed, the valve 25 is opened, and the regenerated waste liquid is sent to the recovery tank.

According to the method of reusing the regenerated liquid shown in Tables 4 and 5, the amount of regenerated liquid can be reduced by increasing the number of reuses. This is because, as shown in Figure 1, in recent boiling water nuclear power plants, the condensate filtration demineralizer 5 is installed before the condensate demineralizer 6, so the condensate demineralizer resin Since the amount of io/and crud loading on the condensate demineralizer resin has decreased, regeneration is only carried out once or twice a year. do not have. Therefore, one of the above regenerations is carried out during the regular inspection period, and the resin regeneration of the condensation tower is carried out at -i. Regeneration liquid at this time? The effectiveness of reusing methods becomes greater.

Moreover, if this method is fully adopted, the current 1100 MWe class plant will have lθ~11#! Therefore, if regeneration is repeated three times with one regeneration liquid, the amount of regeneration waste liquid generated can be reduced by about 60 cm. In addition, in plants without seawater leaks, the amount of load on the resin is extremely small, so the amount of regenerated liquid at one time can be used at least three times (5 to 6 times).
times) Can be used to trap 70~ SOW can be reduced.

Furthermore, unless frequent regeneration is required due to a seawater leak, sufficient time is often required for regeneration. Moreover, this is not the case for regeneration performed during periodic inspections.

Therefore, is it possible to improve the resin regeneration efficiency by slowing down the flow rate of the regeneration liquid shown in FIGS. 6 and 7? There are many times when measuring methods can be adopted. Furthermore, as shown in FIGS. 6 and 7, the crud in the regenerated liquid is removed by the filter 31, which increases the number of times the regenerated liquid is used. Further increases are possible.

If this method is adopted, as shown in Figure 3, water transportation l
If L is reduced to 1/2 of the normal value, the regeneration efficiency will be approximately doubled, making it possible to reduce the usage impact of the regeneration liquid to 1/2 or less.

By combining the above two regeneration methods, it is possible to reduce the amount of waste liquid generated under normal regeneration conditions by approximately 8 liters.

〔Effect of the invention〕

The number of waste drums generated during the condensate demineralizer resin regeneration in the current 1000 MWe class nuclear power generation furnace is about 200, so if the present invention is adopted, the number can be reduced to about 40.

The present invention is applicable to all types of mixed-bed condensate demineralizers, such as pressurized water type nuclear power generation equipment, thermal power generation equipment, etc.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the system of a boiling water nuclear power plant, Figure 2 is an explanatory diagram of a condensate desalination resin regeneration system, and Figure 3 is a diagram of a chemical a11 degree and a An explanatory diagram of the experimental results of changing the water speed. Figures 4 and 5 are system diagrams of the equipment that reuses the recycled waste liquid. Figures 6 and 7 show the water flow rate of the recycled waste liquid. FIG. 6 is a diagram showing slowed regeneration. l...Reactor pressure vessel, 2...High pressure turbine, 3...
...Low pressure turbine, 4 river condenser, 5 river condensate filtration desalination tower,
6... Condensate demineralization tower, 7... Gas extraction system line, 8 River water supply heater, 9... Resin fraction 11 column, 10... Anion exchange resin, 11... Cation exchange resin, 12...
- Blind ion regeneration tower. 1 figure rate 2 figure 3 memorial gift Daido (relative value) 1 figure, 5 figure, 6 figure 'V figure 1st page continuation @ inventor Sansui preference den

Claims (1)

[Claims] 1. Regarding a mixed-bed desalination tower containing a granular cation exchange resin and a small ion exchange resin, the ion exchange resin whose desalination performance has decreased is regenerated in a regeneration tower outside the tower, and the regenerated ion exchange resin is In a method for regenerating a mixed-bed water-covered demineralizer resin in which the desalination column is refilled to desalinate condensate, the regeneration solution used for -y regeneration is repeatedly used for regeneration of multiple ion exchange resins. ft Features: Condensate demineralizer resin regeneration equipment.