JP3137388B2 - Life prediction method of ion exchange resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating the life of an ion-exchange resin packed in a condensate desalination tower of a nuclear power plant using a boiling water reactor (hereinafter referred to as a BWR nuclear power plant). About the method.

[0002]

2. Description of the Related Art The ion exchange resin of a condensate desalination tower used in a BWR nuclear power plant has no fixed use period (life) and should be used as long as possible from the viewpoint of reducing the amount of waste generated. In order to maintain high-purity water quality, it is better to replace it with a new one at each periodic inspection.

On the other hand, if only the condensate desalination tower is used, the performance of removing the clad is improved year by year as shown in FIG. 6. Therefore, in order to reduce the radiation exposure, it is necessary to reduce the carry-in of the clad into the furnace. I had to use the ion exchange resin for many years while worried.

[0004] From experience, even when a cation exchange resin (cation resin) has been used for about 10 years, there is no remarkable decrease in strength and ion exchange capacity. Although the exchange group is weakly basified, it does not contribute to the performance of removing the clad, so that only the anion exchange resin is exchanged.

[0005] However, even if the cation exchange resin is used for a long time even though the strength and the ion exchange capacity are not remarkably reduced, there is a concern about the problem of elution of organic impurities.

[0006]

The problems of the prior art are:
There was no telling how many years the ion exchange resin could be used at the WR nuclear power plant, and over the years of use it had to be used worried about sudden degradation. The problem to be solved by the present invention is that the life of the ion exchange resin cannot be predicted in this way.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. For example, the present invention is based on the prediction of the service life of a cation exchange resin, which greatly affects the performance of removing a clad such as a corrosion product in a coolant, to replace the ion exchange resin. It is an object of the present invention to provide a method for estimating the life of an ion exchange resin, which can give a planner to a product.

[0008]

The present invention measures the amount of iron in a cation exchange resin to determine the conditions for accelerating oxidative deterioration, and then performs an accelerated deterioration treatment by adding an oxidizing agent to the cation exchange resin. Next, the moisture content of the degraded ion exchange resin subjected to the accelerated degradation treatment is measured, the degree of degradation is determined by comparing the moisture content with actual plant data, and then various evaluation tests of the degraded ion exchange resin are performed. Then, the evaluation test results
Pre the life of the ion exchange resin based on the collation to acceptability determination and previously prepared ion-exchange resin used reference to the row cormorants series of operations
Measurement method, and the above series of operations is performed at several different points.
A different test resin was created and tested under degradation conditions.
Interpolation or from the results of the various evaluation tests of the test resin
Outer insert against the O Ri said ion-exchange resin used criteria Rukoto
Characterized by life predicted.

[0009]

The cation exchange resin of the condensate desalination tower takes in iron into the cation exchange resin particles with the age of use (Fig. 2). Since iron acts as an oxidation catalyst, a small amount of oxidizing agent can cause deterioration according to the amount of intragranular iron. An indicator of deterioration can be seen in “increase in water content”, which can quantitatively represent crosslinking rupture (irreversible swelling) due to oxidation.

From the change in the water content of the cation exchange resin, which is empirically known in the actual plant, the number of years of accelerated deterioration can be determined. On the other hand, the strength, impurity elution characteristics, etc. of the accelerated deterioration ion exchange resin are tested to determine whether or not the resin can be used. Is determined and the life is evaluated.

[0011] The ion exchange resin in the condensate desalination tower removes not only ions but also cladding. Some of the clad is dissolved on the surface of the cation exchange resin and becomes ions to be taken into the ion exchange resin particles. These irons tend to increase year by year because the chemical regeneration of the cation exchange resin is performed with sulfuric acid, which has poor regeneration efficiency. This iron acts as an oxidation catalyst.

On the other hand, the cation exchange resin undergoes oxidation during the operation, swells due to breakage of the crosslinks. Therefore, if a cation exchange resin used in a real machine is sampled and an oxidizing agent is added thereto, irreversible swelling proceeds at an accelerated rate in the presence of an iron catalyst. In this way, the state of the ion exchange resin several years from now can be created, and it is possible to confirm by a test what behavior the ion exchange resin will take.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a method for estimating the life of an ion exchange resin according to the present invention will be described with reference to FIGS. FIG. 1 is a process chart of the life estimation method of the present embodiment, and FIGS.
Shows a relationship curve diagram or diagram during each step in FIG. That is, in FIG. 1, the amount of iron in a cation exchange resin as a sample whose life is to be predicted is measured (reference numeral 1), and a condition for accelerating deterioration is determined (reference numeral 2). The acceleration conditions are defined by the amount of iron in the ion exchange resin, the treatment time with hydrogen peroxide, the treatment temperature, the hydrogen peroxide concentration, and the quantitative ratio of ion exchange resin / hydrogen peroxide.

After accelerated deterioration treatment (reference numeral 3) under these conditions, the moisture content of the ion exchange resin is measured (reference numeral 4), and how many years of deterioration has occurred is compared with the actual plant data (reference numeral 5). Deterioration degree (how many years of use) is determined (reference numeral 6). Next, an evaluation test (reference numeral 7) using the accelerated deterioration ion exchange resin is performed. This evaluation test includes strength, dissolution, exchange capacity, exchange rate, and the like.

The evaluation test result is compared with the ion exchange resin use standard (reference numeral 8) to determine whether the use is possible or not (reference numeral 9). The pass / fail judgment is fed back to the deterioration degree judgment (reference numeral 6), and several different inferiorities are obtained.
Under test conditions, test resins with different degrees of degradation are prepared. This
Interpolated or extrapolated from the results of various evaluation tests of these test resins
By insertion, the ion exchange resin use standard 8 is illuminated.
In addition, by changing the degree of accelerated deterioration by several points, it is possible to make a life expectancy (reference numeral 10) as to how long it can be used thereafter.

FIG. 2 shows the relationship between the amount of intragranular iron in the cation exchange resin and the age of the ion exchange resin. FIG. 3 shows a sample of a condensate desalination tower ion-exchange resin sample that has been used for 5 years and has 9 g of iron per liter of cation-exchange resin.
In this figure, the water content of the ion exchange resin with respect to the treatment time when immersed and left at 60 ° C. in a volume ratio of the hydrogen peroxide solution 10 with respect to the ion exchange resin 1 with respect to the ion exchange resin 1 is shown.

From the result, it was determined how many years the water content was in the actual plant.
Yearly, the ion exchange resin treated for 8 hours shows deterioration for 14 years, and the ion exchange resin treated for 24 hours shows deterioration for 20 years.

Next, when these deteriorated cation exchange resins were immersed in pure water at 30 ° C., the total organic carbon (T
FIG. 4 is a graph in which OC) elution rates are plotted with respect to the number of years of use.
Shown in FIG. 5 shows the relationship between the number of years of use and the crushing strength of the ion exchange resin. When the pass / fail judgment is made based on the use reference values for the characteristics of each ion exchange resin, it is determined that the crushing strength in FIG. 5 can be used up to 18 years, that is, the remaining 13 years, but the TOC elution in FIG. It is determined that only the remaining seven years can be used. In this way, a plurality of criteria are provided, and the shortest life is evaluated on the safe side.

In this example, the life expectancy of the ion exchange resin of the condensate desalination tower used for 5 years was determined to be 7 years. Therefore, a plan is made to replace all towers in seven years. In this case, as described above, there is a concern that replacement of a new ion-exchange resin may lower the clad removal performance. Therefore,
A method of successively exchanging the ion exchange resin over seven years may be adopted, and if there is a lapse of seven years to consider separately installing a clad removing apparatus. On the other hand, from the viewpoint of waste treatment and disposal, the period of seven years will be a sufficient period for considering handling of waste ion exchange resin.

When the amount of iron in the cation exchange resin is large,
Conditions are changed such as lowering the hydrogen peroxide concentration in the embodiment, increasing the capacity ratio of ion exchange resin / hydrogen peroxide solution to lower the accelerated deterioration temperature, and the like. Conversely, when the amount of iron in the cation exchange resin is small, the reverse operation is performed. In the present invention, hydrogen peroxide is used as the oxidizing agent, but the object can be achieved by using another oxidizing agent or an oxidizing device such as ultraviolet rays.

Although the TOC elution rate and the crushing strength were used to judge the applicability, it is more accurate to perform a multifaceted evaluation by using other criteria such as ion exchange capacity and ion exchange rate. In addition, iron is added to a new ion exchange resin by cladding or ions, and the accelerated deterioration and life evaluation of the present invention are performed.

[0022]

According to the present invention, the replacement time of the ion exchange resin can be predicted, so that the replacement of the ion exchange resin can be planned. Therefore, the stock period of a new ion exchange resin can be shortened, and it is economical, and at the same time, deterioration during storage can be minimized. In addition, by avoiding simultaneous replacement of all of the condensate desalination towers, TO
It is possible to eliminate from both sides of C and the clad.

[Brief description of the drawings]

FIG. 1 is a process diagram showing one embodiment of a method for predicting the life of an ion exchange resin according to the present invention.

FIG. 2 is a curve diagram showing the relationship between the amount of intragranular iron of the cation exchange resin in FIG. 1 and the years of use.

FIG. 3 is a curve diagram showing the relationship between the water content of the cation exchange resin and the oxidation treatment time in FIG.

FIG. 4 is a diagram showing the relationship between the TOC dissolution rate and the number of years of use in the evaluation test in FIG.

5 is a curve diagram showing the relationship between the crushing strength and the number of years of use in the evaluation test in FIG.

FIG. 6 is a curve diagram showing the relationship between the clad removal performance and the years of use of the ion exchange resin in the conventional method for predicting the life of an ion exchange resin.

[Explanation of symbols]

1. Measurement of iron content in ion exchange resin. 2. Determination of deterioration acceleration conditions. 3. Acceleration deterioration treatment. 4. Measurement of water content of deteriorated ion exchange resin. 5. Actual plant data. 6. Determination of deterioration degree. 7. ... Evaluation test, 8 ... Ion-exchange resin use standard, 9 ...
Pass / fail judgment, 10 ... Life expectancy.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 47/00-47/14 C02F 1/42 G21C 17/003 G21F 9/12

Claims (1)

(57) [Claims] 1. The method according to claim 1, wherein the amount of iron in the cation exchange resin is measured to determine conditions for accelerating oxidative degradation.
An oxidizing agent is added to the inside for accelerated deterioration treatment, and then the accelerated deterioration
The moisture content of the treated degraded ion exchange resin was measured and this
The water content is compared with the actual plant data to determine the degree of deterioration, then various evaluation tests of the deteriorated ion exchange resin are performed, and then the evaluation test results are compared with a previously prepared ion exchange resin use standard to pass or fail. based on the decision in a row jar series of operations
Method to predict the life of the ion exchange resin, and
The above series of operations is performed under different conditions under several different degradation conditions.
A test resin was prepared and performed.
Said Ri by the Rukoto to interpolate interpolated or out of the seed evaluation test results
A method for estimating the life of an ion-exchange resin, comprising predicting the life of the ion-exchange resin by comparing it with a use standard of the ion-exchange resin.