JPH09178892A - Radioactive contamination suppressing method and primary reactor cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further increase the suppressing effect of radioactivity sticking via the electrolytic polishing of a member kept in contact with a radioactive fluid by suppressing the sticking of a clad. SOLUTION: A zero-energy thermonuclear apparatus(ZETA) potential measuring device 37 continuously measuring the ZETA potentials of a granular corrosive product and a structural material applied with electrolytic polishing and a clad ZETA potential adjusting device 39 adjusting the ZETA potential of the granular corrosive product are installed on the outlet side of a recirculation pump 17. The ZETA potential of the corrosive product in a coolant is adjusted by these devices 37, 39 so that repulsive force is applied between a clad which is the granular corrosive product and the structural material applied with electrolytic polishing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radioactive contamination suppressing method for reducing the amount of radioactivity adhering to a structural material which is in contact with a radioactive fluid such as a coolant in a radioactive material handling facility such as a nuclear power plant, and a method for suppressing the radioactive contamination. The present invention relates to a primary cooling system for a nuclear reactor in which the amount of radioactivity attached to a structural material is reduced by the method.

[0002]

2. Description of the Related Art At present, the mainstream of nuclear power plants in Japan is light water reactors such as boiling water reactors (BWRs) and pressurized water reactors (PWRs). In these light water reactors, light water (normal water) not only acts as a moderator that slows down neutrons, but also acts as a medium that transfers generated heat.

FIG. 16 schematically shows a BWR primary cooling system, in which light water circulates in each system as a coolant mainly in the nuclear reactor. That is, the steam generated in the core 3 in the reactor pressure vessel 1 passes through the steam line 5 and the turbine 7
Turning the. The steam that has worked in the turbine returns to water in the condenser 9. The water is condensed by the condensate pump 11 into a condensate purification device
After removing the impurities, it is preheated by the feed water heater 15 and returned into the reactor pressure vessel 1. Further, the reactor water is forcedly circulated by the recirculation pump 17 and the jet pump 19. Further, a part of the reactor water flowing through the reactor water recirculation system is cooled by the reactor water purification system pump 21 by the regenerative heat exchanger 23 and the non-regenerated heat exchanger 25, and then purified by the reactor water purification device 27, It is brought back into the reactor from the water supply system.

In some plants, the reactor water purification system pump 21 is arranged downstream of the regenerative heat exchanger 23 or the non-regenerative heat exchanger 25. Furthermore, a plant (called ABWR), which does not have a reactor water recirculation system, is equipped with a plurality of pumps called internal pumps inside the reactor and forcibly stirs the reactor water with this. , The number of plants of this type tends to increase in the future.

By the way, on the surface of the fuel cladding tube, the following phenomenon occurs with the heat transfer from the nuclear fuel to the coolant. For example, in a BWR, a particulate metal oxide (generally called a clad) containing iron as a main component such as a corrosion product brought in from a water supply / condensation system or an ionic impurity is caused by a boiling phenomenon or a eutectoid reaction. It is immobilized on the surface of the fuel cladding tube.

Here, the adhesion of the particulate metal oxide by the boiling phenomenon means that the particulate metal oxide containing iron as a main component is seized and adhered to the dry surface generated on the surface of the fuel cladding tube by boiling. It is a phenomenon that is fixed by.

The adhesion of ionic impurities by the eutectoid reaction refers to a phenomenon in which the adhered particulate metal oxide and ionic impurities form a composite oxide and are immobilized on the surface of the fuel cladding tube. There is. As a reaction of this kind, a reaction in which nickel ferrite is produced from Fe ₂ O ₃ + Ni ²⁺ + H ₂ O → NiFe ₂ O ₄ + 2H ⁺ iron clad and nickel ions is well known as follows.

Further, in the PWR, the boiling phenomenon on the fuel surface is limited to only the upper portion of the fuel rod, so that the amount of these deposits is smaller than that of the BWR, but the above-mentioned deposit phenomenon is observed.

On the surface of the fuel cladding tube, these corrosion products are irradiated with neutrons and are activated to be converted into radioactive corrosion products. The total amount of the generated radioactive corrosion products is not fixed on the fuel surface as it is, but some of them are exfoliated in the form of particles or are eluted in the form of ions, which causes the radioactivity in the primary coolant. It will increase the concentration.

The radioactive material generation process includes a process in which corrosion products are separated / eluted from the in-core structural material and fixed on the fuel surface to be activated, or the core structural material is directly activated in that part. A process of elution as a radioactive corrosion product is also considered.

The radioactive substances generated through various processes reach the whole area of the primary cooling system of the plant by using the primary cooling medium as a medium and contaminate each system.

It is believed that the main process for incorporating the particulate radioactive material into the structural material of the primary cooling system is physical adsorption on the material surface or adhesion by gravity settling.

On the other hand, it is understood that an ionic radioactive substance is codeposited as an oxide in a corrosion film formed on the surface when a metallic material is corroded, or incorporated by an isotope exchange reaction. For example, ⁶⁰ Co ₂₊ is associated with the corrosion of steel materials by the following two equations: ⁶⁰ Co ₂₊ + 2Fe ₃₊ + 4H ₂ O + 8e ⁻ → ⁶⁰ CoFe ₂
O are considered to be incorporated in the coating in _{^{4 + 4H 2 60 Co 2+ +}} CoFe 2 O 4 → Co 2+ + 60 CoFe 2 O 4.

In this way, the metallic material in contact with the primary coolant takes up the radioactive substance, and the amount thereof increases with the rate of increase over time due to the growth of the corrosion film and the rate of uptake of the particulate radioactive substance. The rate will continue to increase until it balances with the rate at which the amount of radioactive material already deposited due to radioactive decay decreases.

Accumulation of radioactive substances on the inner surface of pipes and the surface of equipment increases the radiation exposure of workers who carry out disassembly and inspection of the parts and equipment. As a result, the exposure rate to workers who perform other work in the vicinity increases as well. As a result, the total exposure dose (total Munchie belt) during the plant operation and the periodic inspection period is increased. This leads to an increase in the cost of the periodic inspection due to an increase in the number of workers and an extension of the period of the periodic inspection. On the other hand, it becomes a social problem and hinders the construction of a new plant. Against this background,
Actively researching methods for suppressing the accumulation of radioactive substances and methods for removing once accumulated radioactive substances (decontamination methods).

When the migration behavior of these radioactive substances is comprehensively examined, in order to suppress the increase in the air dose rate due to the adhesion of the radioactive corrosion products to the surface of the primary system piping and the surface of the equipment, (1) radioactive corrosion No product is generated, (2) Radioactive material is retained at the generation site and is not transferred to reactor water,
(3) Remove the radioactive substances that have migrated to the reactor water, do not increase the concentration in the primary coolant, (4) do not attach the radioactive substances to the pipe surface or equipment, (5) remove the attached radioactive substances, etc. Countermeasures are possible.

The technique described in Japanese Examined Patent Publication No. 2-2520 is made from the viewpoint of (4).
By subjecting the contact surface with the radioactive fluid to electropolishing, the formation of a corrosion layer is suppressed, and as a result, the amount of ionic radioactive substances taken into the corrosion layer is reduced to reduce radioactive contamination. .

[0018]

The above-mentioned technique suppresses the adhesion of ionic radioactive substances, but the effect of suppressing the adhesion of particulate radioactive substances has hardly been mentioned and it was unclear.

Therefore, the present inventor conducted the following radioactive adhesion test in order to evaluate the effect of electrolytic polishing on the adhesion of particulate radioactive substances.

First, as shown in FIG. 17, pipe-shaped test pieces A, B, C and A'made of stainless steel were connected using a joint 4D. The test piece A and the test piece A ′ had the same inner surface and had the same specifications. The test piece B has an inner surface that is electrolytically polished, and the test piece C has a different degree of electrolytic polishing and is smoothed more than the test piece B. The average line surface roughness Ra (μm) (measured by a stylus type surface roughness meter) of the inner surface of each of these test pieces before the radioactivity adhesion test was measured by the test pieces A (A ′), B and C, respectively. 3.0,
0.9 and 0.1. Here, the surface roughness Ra means that a portion of the measurement length l is cut from the roughness curve in the direction of the center line, the center line of the cut portion is taken as the X-axis, and the direction of longitudinal magnification is taken as the Y-axis. When a curve is represented by y = f (x), the following equation

[Equation 1] The value obtained by is expressed in units of micrometers (μm), and the smaller the value, the smoother it is.

Next, two test pieces consisting of the above four test pieces are arranged as shown in FIG. 18, and the upstream side is the first test piece 6a and the downstream side is the second test piece 6b. High-pressure high-pressure water at 70 atm and 280 ° C was passed through the test body of No. 2. Further, ⁶⁰ Co solution from the first injection line 8a of the high-temperature high-pressure water first specimen 6a just before the iron clad from the second specimen 6b immediately before the second injection line 8b, respectively, ⁶⁰
Co was injected at a concentration of 0.01 Bq / ml in high-temperature water and an iron clad of 20 ppb. In this radioactivity attachment test, water flow was stopped about every 100 hours, the amount of radioactivity attached was measured, and the change was followed.

FIG. 19 shows the result of the radioactivity adhesion test in the first test body 6a, that is, in the environment without the iron clad. First, since the test pieces A and the test pieces A ′ have almost the same amount of adhesion, it is evaluated that there is no influence of the position, that is, the decrease of the radioactivity concentration due to the consumption of ⁶⁰ Co. Although the amount of radioactivity increases with time, it is clear that test piece A
(A ') was the largest, test piece B was the second, and test piece C was the smallest. This indicates that the electropolishing suppresses the adhesion of ionic radioactive substances.

FIG. 20 shows the result of the radioactivity adhesion test in the environment where the second test body 6b, that is, the iron clad coexists. The order of the attached amount of radioactivity is test piece A (A ′)> test piece B> test piece C as in the case of the first test body 6a, but the absolute amount is obviously higher than that of the first test body 6a. There were many. This result means that the amount of radioactivity attached increased due to the coexistence of iron clad in water.

After completion of the radioactivity adhesion test, the test piece is analyzed,
Two reasons were investigated: a cause of a small amount of radioactivity adhering to the electrolytically polished test piece in an environment without an iron clad, and a cause of an increase in the amount of adhering radioactivity due to the coexistence of the iron clad.

As a result, it was found that the cause of the small amount of radioactivity adhering to the electrolytically polished test piece in the environment without the iron clad was as described in the above Japanese Patent Publication No. 2520/1990. . That is, in an environment in which only ionic radioactive substances are present, ionic radioactive substances are incorporated in the corrosion film generated along with the corrosion of the wetted part of the structural material. It is generated as a result of the fact that the corrosion of the structural material was suppressed by applying electrolytic polishing to the material of the wetted part of "," or "the effective surface area was reduced by smoothing by electrolytic polishing". The amount of oxide film per unit area decreases,
The amount of radioactivity taken in is suppressed.

On the other hand, the following results were obtained regarding the cause of the increase in the attached radioactivity in the environment where the iron clad coexists. That is, not only the usual corrosion film is generated and the radioactivity is taken into the test piece of the second test body 6b subjected to the radioactivity adhesion test in the environment where the iron clad coexists, Iron clad adheres and ⁶⁰ Co
Was taken in, and as a result, it was found that the amount of attached radioactivity was increased as compared with the first test body 6a. Further, when observed in detail, the clad adhered was present so as to be incorporated in the corrosion film of the base material, and was hardly detached by a treatment such as ultrasonic cleaning. This means that the adhesion of the iron clad increases the number of sites for radioactivity, and from a different perspective, the adhesion of the iron clad means that the corrosion of the test piece was promoted and the amount of corrosion film increased. It turned out to produce the same result as.

FIG. 21 is a diagram obtained by subtracting FIG. 20 from FIG. 20, and shows the change in the amount of radioactivity increased by the adhesion of the iron clad. It should be noted in FIG. 21 that the amount of radioactivity increased by the adhesion of the iron clad changes depending on the surface condition of the test piece. Test piece A, A '
Although the increasing tendency of the amount of radioactivity due to the adhesion of the iron clad to the steel was initially larger than that of the electrolytic polishing test pieces (test pieces B and C), the increasing tendency was measured so as to gradually become saturated. On the other hand, the increase in radioactivity due to the adhesion of the iron clad to the electropolished test pieces (test pieces B and C) was almost linear. From this, it can be said that the iron clad is more likely to adhere to the electropolished test piece in the medium to long term, and there is a concern that the amount of radioactivity will exceed that of the untreated material due to the extension of the test time. In any case, it can be said that the adhesion of the iron clad increases the amount of the radioactive substance deposited, and there is a risk that the effect of suppressing the deposition of the radioactivity due to the electrolytic polishing is offset.

In this test, it is presumed that the iron clad first adhered to the inner surface of the test piece and then ⁶⁰ Co was taken therein, but the same result was obtained even if the iron clad containing ⁶⁰ Co was adhered in advance. it is conceivable that. In other words, this test can be interpreted as a test in which a particulate radioactive substance was taken in.

The present invention has been made in consideration of the results of the above radioactive deposition test, and is intended to suppress the increase of the air dose rate due to the deposition of radioactive corrosion products on the surface of the primary system piping and the equipment surface. Among the above-mentioned five measures of (1), from the viewpoints of (1) no generation of radioactive corrosion products and (4) no adhesion of radioactive substances to the pipe surface and equipment, the effect of suppressing the adhesion of radioactivity by electrolytic polishing treatment It is an object of the present invention to provide a method for suppressing radioactive contamination that can further increase the air dose rate and suppress the exposure of workers, and a primary cooling system for a reactor embodying this method.

[0030]

That is, according to the invention of claim 1, in a method for suppressing radioactive contamination of a member which is in contact with a radioactive fluid, the liquid contact surface of the member is electrolytically polished in advance and the member is It is characterized in that it is formed of a metal material having a monthly corrosion release amount of 1 mg / dm ² or less at an operating environment temperature.

The invention of claim 2 is characterized in that, in the method for suppressing radioactive contamination, particulate matter of 0.1 μm or more is removed from the radioactive fluid in contact with the member.

According to a third aspect of the present invention, in a method for suppressing radioactive contamination of a member that comes into contact with a radioactive fluid, the liquid contact surface of the member is electrolytically polished in advance, and the zeta potential of the liquid contact surface and the radioactive fluid It is characterized in that at least one of the zeta potentials is adjusted so that the difference from the zeta potential of the particulate matter is reduced to electrostatically suppress the adhesion of the particulate matter to the liquid contact surface.

The invention of claim 4 is characterized in that the zeta potential of the liquid contact surface of the member is adjusted by polarizing the member.

The invention of claim 5 is characterized in that the zeta potential of the liquid contact surface of the member is adjusted by forming an oxide film on the liquid contact surface in advance.

The invention of claim 6 is characterized in that an oxide film is formed on the liquid contact surface by contacting the liquid contact surface with high temperature water of 250 ° C. or higher for 500 hours or longer.

The invention of claim 7 is characterized in that the high temperature water has an electric conductivity at 25 ° C. of 1 μS / cm or less and a dissolved oxygen concentration of 1 ppm or more.

The invention of claim 8 is characterized in that the zeta potential of the particulate matter in the radioactive fluid is adjusted by changing the crystal form of the particulate matter.

The invention of claim 9 is characterized in that the zeta potential of the particulate matter in the radioactive fluid is adjusted by changing the particle size of the particulate matter.

According to a tenth aspect of the present invention, in a method for suppressing radioactive contamination of a member which comes into contact with a radioactive fluid, the liquid contact surface of the member is subjected to electrolytic polishing in advance, and secondarily even when it is activated by activation. It is characterized in that metal ions whose isotope ratio is adjusted so as not to generate radionuclides are injected into a radioactive fluid.

In the eleventh aspect of the present invention, the metal ion whose isotope ratio is adjusted is Mg, Cr-50 excluding Mg-26.
Cr excluding Cr, V excluding V-51, T excluding Ti-50
i, Ni-58, Ni-62 and Ni except Ni-64,
Zn and Cd excluding Zn-64, Zn-68 and Zn-70
Cd excluding -114, Mo excluding Mo-98, W-184
And at least one selected from the group consisting of W and Nb excluding W-186.

According to a twelfth aspect of the present invention, in a method for suppressing radioactive contamination of a member that comes into contact with a radioactive fluid, the liquid contact surface of the member is electrolytically polished in advance, and the pH of the radioactive fluid is adjusted to alkali metal ions or alkaline earth. It is characterized in that it is adjusted to be neutral to weakly alkaline by at least one of the group metal ions.

The thirteenth aspect of the present invention is the method for suppressing radioactive contamination according to the twelfth aspect, wherein at least one of an alkali metal ion and an alkaline earth metal ion substantially corresponding to the ion equivalent concentration of soluble chromium in the radioactive fluid is used. Is injected into the radioactive fluid.

According to a fourteenth aspect of the present invention, the p of the radioactive fluid is
The feature is that H is adjusted so that the pH at 25 ° C. is 8.6 or less.

According to a fifteenth aspect of the present invention, in the reactor primary cooling system in which the primary coolant of the nuclear reactor circulates, the liquid contact surface of the structural material which comes into contact with the primary coolant is electrolytically polished in advance, and The filter is characterized by comprising at least one of a filter desalting filter, a hollow fiber filter and a ceramic filter for removing particulate matter of 0.1 μm or more.

According to a sixteenth aspect of the present invention, the structural material has a corrosion emission amount of 1 mg / dm / month at the ambient temperature of use.
It is characterized by being formed of a metal material of ² or less.

According to a seventeenth aspect of the present invention, in the reactor primary cooling system in which the primary coolant of the nuclear reactor circulates, the liquid contact surface of the structural material which comes into contact with the primary coolant is subjected to electrolytic polishing in advance, and the electrolytic material of the structural material is electrolyzed. A zeta potential measuring device that measures the zeta potential of the wetted surface and the zeta potential of the particulate matter in the primary coolant, and a zeta potential that adjusts the zeta potential of the wetted surface or the zeta potential of the particulate matter. And an adjusting device.

The invention of claim 18 is characterized in that the zeta potential adjusting device adjusts the zeta potential of the particulate matter by changing its crystal form or crystal grain size.

The invention of claim 19 is characterized in that the zeta potential adjusting device adjusts the zeta potential of the liquid contact surface by polarizing the structural material.

According to a twentieth aspect of the present invention, the zeta-potential adjusting device comprises a structural member in which each connecting portion is insulated by inserting a packing, an electrode axially installed in the inner center of the structural member, and a structure. It is characterized in that it has a direct current power source for supplying a direct current between the material and the electrode.

According to a twenty-first aspect of the present invention, in the reactor primary cooling system in which the primary coolant of the nuclear reactor circulates, the liquid contact surface of the structural material which comes into contact with the primary coolant is electrolytically polished in advance, and this electrolytic polishing is performed. It is characterized in that an oxide film is formed on the applied liquid contact surface to previously adjust the zeta potential of the liquid contact surface.

According to a twenty-second aspect of the invention, in the reactor primary cooling system according to the twenty-first aspect, the conductivity at 25 ° C. is 1 μS / cm.
In the following, an oxide film is formed in advance by bringing pure water having a dissolved oxygen concentration of 1 ppm or more into contact with the liquid contact surface at a temperature of 250 ° C. or more for 500 hours or more.

According to a twenty-third aspect of the present invention, in a reactor primary cooling system in which the primary coolant of the nuclear reactor circulates, the liquid contact surface of the structural material which comes into contact with the primary coolant is preliminarily electropolished, and The metal ion implanter that injects into the primary coolant metal ions whose isotope ratio has been adjusted so that secondary radionuclides are not generated even when brought in, and the concentration of metal ions in the primary coolant And a metal ion monitoring device for monitoring and controlling the implantation amount of metal ions.

According to a twenty-fourth aspect of the present invention, the metal ion implanting apparatus comprises means for blowing carbon dioxide gas into pure water to generate an electrolytic solution, and the generated electrolytic solution containing a metal element whose isotope ratio is adjusted. A means for generating a metal ion whose isotope ratio is adjusted by dipping multiple metal plates and applying a DC voltage between these plates, and degassing carbon dioxide gas from the electrolytic solution containing this metal ion to perform primary cooling. And a means for removing carbon dioxide gas supplied into the material.

In the twenty-fifth aspect of the present invention, the metal ion implanting apparatus allows high temperature water to pass through a column packed with particles of a metal or oxide thereof whose isotope ratio is adjusted, and the metal released by a corrosion reaction. It is characterized by including means for supplying high-temperature water containing ions into the primary coolant having substantially the same high temperature.

According to a twenty-sixth aspect of the present invention, in the nuclear reactor primary cooling system according to the twenty-fifth aspect, the metal oxide is a sintered body which is fired at a temperature of half or more of a melting temperature of the metal oxide.

According to a twenty-seventh aspect of the present invention, in the nuclear reactor primary cooling system according to the twenty-fifth aspect, the high-temperature water is a primary coolant collected by a shunt.

In the twenty-eighth aspect of the present invention, the metal ion implantation apparatus is a solution or a solution containing at least one compound selected from the group consisting of hydrides, hydroxides and metal salts of isotope-adjusted metals. It is characterized by including means for supplying the slurry into the primary coolant.

According to a twenty-ninth aspect of the present invention, the metal ion whose isotope ratio is adjusted is Mg, Cr-50 excluding Mg-26.
Cr excluding Cr, V excluding V-51, T excluding Ti-50
i, Ni-58, Ni-62 and Ni except Ni-64,
Zn and Cd excluding Zn-64, Zn-68 and Zn-70
Cd excluding -114, Mo excluding Mo-98, W-184
And at least one selected from the group consisting of W and Nb excluding W-186.

According to a thirtieth aspect of the present invention, in the reactor primary cooling system in which the primary coolant of the nuclear reactor circulates, the liquid contact surface of the structural material in contact with the primary coolant is electrolytically polished in advance, and Chromium concentration monitoring means for monitoring the chromium concentration of the liquid, and based on the monitoring results of the chromium concentration monitoring means, at least one of alkali metal ions and alkaline earth metal ions is adjusted so as to match the ion equivalent of the chromium concentration in the primary coolant. And an alkali supply means for supplying one of them into the primary coolant.

In obtaining the invention of each of the above claims, the present inventor, in order to investigate the cause of the difference in the adhesion of the iron clad between the electrolytic polishing material and the untreated material, following the above-mentioned radioactivity adhesion test. The following additional tests were conducted.

FIG. 22 shows the measurement results of the zeta potential of the iron clad added in the radioactivity adhesion test. The measurement was performed at 25 ° C. with pΗ as a parameter. In general, particulate matter exhibits a unique electrokinetic potential in water, which is called zeta potential. The zeta potential is the portion of the potential difference at the interface between a solid and a liquid that effectively acts on the electrokinetic phenomenon, and represents the potential difference between the electrically fixed phase on the solid surface and the liquid.

As is clear from FIG. 22, the zeta potential of the iron clad changes with pH, and the pH shows a plus on the acidic side and a minus on the alkaline side. In addition, the potential is reversed in the neutral region (potential becomes zero: PEC) pH
There are conditions. Ultrapure water is used in the primary system of BWR, and it is operated at a pH value of 25 ° C in the vicinity of 7, but the iron clad used in this test is slightly positively charged at pH = 7. I understand.

On the other hand, FIG. 23 shows the same measurement performed on the test piece A and the test piece C. Although the measurement results of both show the same pH dependence as the iron clad, there is a difference in the value at pH = 7. That is, both were negative at pH = 7, and the absolute value was larger in the test piece C subjected to electrolytic polishing treatment.

FIG. 24 shows the results of an iron clad adhesion test at 25 ° C. The test procedure is as follows. First, prepare a test piece as shown in Fig. 17, and include 1 ppm of the same iron clad as that added in the radioactivity adhesion test.
C water was supplied. Under that condition, an adhesion test of the iron clad was carried out for 10 hours using pΗ as a parameter. The pH was tested in the range of 4 to 10 and adjusted by appropriately adding NaOH and HCl.
After the clad adhesion test, the test piece was analyzed for each pΗ condition, and the amount of iron clad adhering to the inner surface of the test piece was measured.

As a result, although significant iron clad adhesion was observed at pH = 7, almost no iron clad adhesion was observed under other pH conditions. This is understood as follows. That is, the adhesion of the iron clad to the test piece is dominated by electrostatic force such as the zeta potential, and only under the condition pΗ = 7 where the zeta potential of the iron clad and the zeta potential of the test piece have different signs. , The attractive force was exerted on both, and the iron clad adhered to the test piece.
It is considered that under the conditions, both zeta potentials had the same sign, so that repulsive force was exerted and repulsed each other, and the adhesion phenomenon was not seen.

Further, FIG. 24 shows that more iron clad adhesion was measured in the test piece C subjected to electrolytic polishing, and there is a risk that the electrolytic clad surface becomes larger in terms of iron clad adhesion. There is.

By the way, the radioactivity adhesion test whose results are shown in FIGS. 19 to 21 was carried out with high temperature water of 280 ° C., and the results of the adhesion test of the iron clad carried out at 25 ° C. shown in FIG. 24 are applied as they are. Although not possible, it is easily conceivable that even at 280 ° C, electrostatic forces such as zeta potential have a great influence on the adhesion phenomenon of the iron clad. It is considered that at 280 ° C, a corrosion oxide film is formed on the inner surface due to contact with high temperature water, and the zeta potential of the test piece changes with time.

FIG. 25 conceptually shows the time variation of the zeta potential of the test piece. Here, the test piece a is a test piece that has been pre-oxidized with high-temperature water at 280 ° C., and the test piece b has the same specifications as the test piece a, but is not pre-oxidized. As a result of the preliminary oxidation treatment, an oxide film is formed on the test piece a, and the test piece b shows a metallic luster.

When the test pieces a and b were brought into contact with high-temperature water at 280 ° C., the zeta potential of the test piece a showed a constant value, but the test piece b initially showed a low potential, and the test piece a with time passed. Asymptotic to the value of. The change in the zeta potential of the test piece b corresponds to the formation process of the oxide film, is low on the metallic glossy surface, and approaches the value of the test piece a as the oxide film grows. When the zeta potential of the test piece is low, the difference from the zeta potential of the iron clad becomes large, which causes an increase in the adhesion amount. This suggests that the adhesion of the iron clad is accelerated immediately after the test. Considering the nuclear power plant, it can be said that there is a risk that the adhesion of the iron clad is accelerated especially during the period when the oxide film is being formed on the liquid contact part immediately after the operation of the new plant is started.

The test results shown in FIGS. 22 to 25 are summarized. By electrolytically polishing the contact surface with the radioactive fluid, it is possible to effectively suppress the uptake of ionic radioactive substances. Incorporation of radioactive substances (including the phenomenon in which iron clad adheres and is incorporated therein) is strongly controlled by the electrostatic force between the iron clad (particulate radioactive substance) and the liquid contact material. Cage,
It is concluded that this occurs regardless of the presence or absence of electropolishing treatment, and there is a risk that the amount adhered to the electropolishing surface will increase depending on the conditions.

However, in any case, the adhesion of the iron clad means increasing the adhesion amount of the particulate radioactive material, and it can be said that there is a risk that the effect of suppressing the adhesion of the radioactivity by the electrolytic polishing is offset.

Based on such test results, the inventor of the present invention, for example, in the case of performing electrolytic polishing on a material in contact with liquid for the purpose of suppressing adhesion of radioactivity in a nuclear power plant or the like, From such a point of view, we have come to the conviction that the effect of suppressing radioactivity adhesion can be further enhanced.

1) It is necessary to remove the corrosion products containing iron clad as a main component, or so-called particulate radioactive substances, which are radioactiveized on the fuel surface. Especially,
Immediately after the start of plant operation, there is a risk that the adhesion of iron clad will be accelerated, so caution is required.

2) Even under water conditions where removal of particulate radioactive material can be expected to effectively suppress the attachment of ionic radioactivity, there is a corrosion oxide film that is the site of radioactivity attachment. The phenomenon of uptake of ionic radioactive substances into the still occurs. In the phenomenon that ionic radioactive substances are incorporated into the oxide film due to the formation of the oxide film, suppressing the amount of ionic radioactive substance incorporated by allowing metal ions to coexist in the coolant under appropriate conditions. You can

3) By properly adjusting the water quality, it is possible to suppress the growth of the oxide film and reduce the amount of ionic radioactive substances taken up.

The main suppression methods in the present invention are
(1) Corrosion products containing iron clad as a main component, and suppressing the generation of so-called particulate radioactive materials that are activated on the fuel surface, (2) Corrosion products containing iron clad as a main component Substances, and the suppression of the so-called particulate radioactive substances, which have been activated on the fuel surface, on the electropolished surface, (3) Suppression of ionic radioactive substances taken into the oxide film by the coexistence of metal ions (4) Suppressing the growth of the oxide film itself, which is the site for incorporating radioactivity, by adjusting the water quality.

First, (1) a corrosion product containing iron clad as a main component, or those produced by activation on the fuel surface,
Means and actions for suppressing the generation of so-called particulate radioactive material will be described.

As a method for suppressing the generation of corrosion products containing iron clad as a main component, or so-called particulate radioactivity generated by activation of these on the fuel surface, the generation amount itself at the corrosion product generation site How to regulate
There are two methods of preventing the generated particulate corrosion products from being brought into the reactor.

The generation part of the corrosion products is the liquid contact part of the piping material and the liquid contact part of the constituent equipment in all the systems in which the primary cooling water of the nuclear power plant circulates. Corrosion is generated by using stainless steel containing iron, chromium, and nickel as the main components for these wetted parts, and limiting the amount of corrosion released to 1 mdm (mg / dm ² / month) or less at each operating environment temperature. It is possible to drastically reduce the amount of generated materials.

By the way, in a light water reactor that uses water as a heat transfer medium, it is impossible to suppress the amount of corrosion products generated to zero by the existing technology. Therefore, a method is effective in which the particulate corrosion products generated and transferred into the coolant are collected by a filter and not brought into the reactor. As the filter for recovery, a filter desalting filter having a structure in which crushed resins are laminated, a hollow fiber filter having a macaroni structure, a ceramic filter, or the like can be applied. Using these filters, particles with a size of 0.1 μm or more can be efficiently collected.

(2) Corrosion products containing iron clad as a main component, and means and functions for suppressing adhesion of so-called particulate radioactive substances, which are activated on the fuel surface, to the electrolytically polished surface. Will be described.

In order to suppress the corrosion products containing iron clad as a main component and the so-called particulate radioactive substances, which are activated on the fuel surface, on the electropolished surface, the adhesion mechanism is a zeta mechanism. The electrostatic force such as electric potential may be used in reverse. That is, it suffices to adjust so that the repulsive force acts on the corrosion product containing iron clad as a main component and the electrolytically polished surface to repel each other. The zeta potential of the iron clad changes depending on its crystal form and crystal grain size. Therefore, these properties can be used to arbitrarily control the zeta potential of the iron clad to suppress the adhesion to the electropolished surface.

The iron clad observed in a nuclear power plant is classified according to its crystal form, hematite (αFe ₂ O ₃ ), magnetite (Fe ₃ O ₄ ), goethite (γFeOOΗ), and lepidocrocite (αFeO).
There is also an amorphous component which is Η) and which does not exhibit a crystalline form. The zeta potential of the iron clad changes depending on its crystal form and crystal grain size.

FIG. 26 shows an example of measurement of the zeta potential of the iron oxide of the reagent, which summarizes the results with pH as a parameter. As is clear from this figure, the zeta potential changes with pH and also with the difference in crystal form. Further, FIG. 27 shows that even if hematite has the same crystal morphology, the zeta potential differs depending on the size of the crystal grain size.

Therefore, it is considered possible to arbitrarily control the zeta potential of the iron clad by utilizing such a property.

On the other hand, it is also possible to suppress the adhesion of the iron clad by polarizing the electropolished surface and controlling the zeta potential of the liquid contact member.

Further, there is also a method of using a liquid contact material whose zeta potential of the electrolytically polished surface is adjusted in advance. For this purpose, there are a method of pre-oxidizing the target member in another place at the ambient temperature, and a method of attaching the member to a service site and then pre-filming by circulating hot water.

Next, (3) the means and action for suppressing the radioactivity incorporated in the oxide film by the coexistence of metal ions will be described.

Japanese Patent Publication No. 3-14155 discloses a method for suppressing the attachment of radioactive ions to a structural material in contact with a cooling material containing radioactive ions, in which the metal in the cooling material is in operation during the operation of the atomic couplant. Measure the amount of ions,
Based on this measurement value, Mg, Cr, V, Ti, Cu, Ni, so that the amount of metal ions in the coolant becomes a predetermined value,
At least one selected from the group consisting of Zn and Cd
Disclosed is a method for suppressing radioactive ion attachment, which comprises injecting metal ions of a seed material into the coolant.

As a result of conducting a test in accordance with the contents disclosed in this publication and confirming its effectiveness and elucidating the mechanism thereof, the present technology shows that ionic radioactive substances are associated with corrosion of structural materials. It was clarified that the rate of uptake of these radioactive ions was governed by the competitive reaction with the coexisting metal ion species in the process of being incorporated into these corrosive films, and that this principle was utilized.

That is, the uptake of ions into the corrosion film is governed by the concentration ratio of radioactive ions and other coexisting ionic species in the solution, although the size is small or large. When the coexisting ionic species concentration is high, As a result, it was found that the amount of radioactive ions incorporated into the corrosion film was suppressed.

In a nuclear power plant in which a liquid contact portion of a coolant containing a radioactive substance is electrolytically polished, it is effective to apply this technique as it is in order to more effectively suppress the adhesion of radioactivity. Although it is a means, it has been found that this technique has the following problems.

Mg, Cr, V, Ti, CU, Ni, Zn
Although metal ion implantation of Cd and Cd can be expected to suppress the uptake of ionic radioactive substances, a nuclear reaction occurs incidentally, and activation of each injected metal causes ²⁷ Mg,
³¹ Cr, ⁵⁵ Cr, ⁵² V, ⁵¹ Ti, ⁶⁴ Cu, ⁶⁶ Cu, ⁶⁵ N
It produces secondary radioactivity such as i, ⁵⁸ Co, ⁶⁹ Zn, ¹⁰⁷ Cd, ¹¹¹ Cd. Their half-life is shorter than that of ⁶⁰ Co, and the radioactivity decreases in a short time even if they adhere to the pipes, so wait a predetermined time after operation stop and wait for the radioactivity to decrease. Although it has been concluded that there is no problem, a detailed examination in the isotope handbook etc. revealed that not only short-lived nuclides were found in the secondary radionuclide group, but ⁶⁵ Z
It has been found that nuclides with a long half-life such as n are also generated.

From the above, it was found that it is possible to generate no secondary radioactivity at all by adjusting the isotope ratio of the above metal ions. The meaning of adjusting the isotope ratio will be described below by taking Mg as an example.

In the natural world, Μg is ²⁴ Μg, ²⁵ Mg, ²⁶ M
Abundance ratios of 3 kinds of g are 78.99, 10.00, 11.01% respectively
(Kagaku Binran Basic, edited by The Chemical Society of Japan, published by Maruzen Co., Ltd., 3rd revised edition). Japanese Examined Patent Publication No. 3-14155 describes that ²⁷ Mg is produced when Mg is injected, but this is caused by the absorption of neutrons by ²⁶ Mg by using the isotope ratio without adjustment. And can be expressed by the following reaction formula ²⁶ μg (n, γ) ²⁷ μg.

At this time, if the isotope ratio is adjusted and ²⁶ Mg is excluded and one of ²⁴ Mg and ²⁵ Mg, or Mg consisting of these two components is used, a secondary generated by injecting these is produced. Adhesion of ionic radioactive substances can be suppressed without any significant radioactivity. Thus, adjusting the isotope ratio in the present invention means the above operation.

The smaller the mass, the easier the method for separating isotopes due to the difference in mass number. This can be inferred from the fact that deuterium ( ² H) and tritium ( ³ H) can be separated from hydrogen atoms relatively easily and can be obtained at low cost. With the current technology, it is possible to enrich uranium with a mass number of 230, and since the mass number of the target metal is 110 at the maximum, there is no technical problem. If this technique of adjusting the isotope ratio is used, not only Mg but also most of the metal ions described in Japanese Patent Publication No. 3-14155 can be applied.

Further, the method of adjusting the isotope ratio of the metal ions described in the above publication will be described below.

Cr: ⁵⁰ C (4.35%) excluded, ⁵² C
The isotope ratio is adjusted to one component of r, ⁵³ Cr, or ⁵⁴ Cr or a multi-component of two or more components. V: ⁵¹ V (99.75%) is excluded, and the isotope ratio is adjusted to consist of ⁵⁰ V only. Τi: ⁵⁰ Ti (5.2%) is excluded, ⁴⁶ Τi, ⁴⁷ Ti, ⁴⁸
Ti, ⁴⁹ to adjust the isotope ratio in one component or two or more multi-component of the .tau.i. Cu: Not applicable Ni: ⁵⁸ Ni (68.3%), ⁶² Ni (3.59%), ⁶⁴ Ni
(0.91%) is excluded and the isotope ratio is adjusted to one or two components of ⁶⁰ Ni and ⁶¹ Ni. Zn: ⁶⁴ Zn (48.6%), ⁶⁸ Zn (18.8%), ⁷⁰ Zn
(0.6%) is excluded and the isotope ratio is adjusted to one or two components of ⁶⁶ Zn and ⁶⁷ Zn. Cd: ¹¹⁴ Cd (28.7%) is excluded, ¹⁰⁶ Cd, ¹⁰⁸ C
d, ¹¹⁰ Cd, ¹¹¹ Cd, ¹¹² Cd, ¹¹³ Cd, ¹¹⁶ C
The isotope ratio is adjusted to one component of d or two or more components.

As described above, in the case of metal species in which the incorporation of ionic radioactive substances is suppressed by the addition of metal ions, adjustment of the isotope ratio eliminates the generation of secondary radioactivity associated with the injection, and the metal ions It can be seen that the injection can be performed more effectively. Further, it is of course possible to adjust the isotope ratio not only for the above-mentioned metal species but also for the metal species for which similar effects can be expected.

Other than the above metal species, molybdenum (M
It was confirmed that o), tungsten (W), niobium (Nb), and tantalum (Ta) have an effect of suppressing the uptake of the ionic radioactive substance. Although molybdenum, tungsten, niobium, and tantalum exist in the BWR primary coolant in the form of metal ions or metal acid ions, molybdenum, tungsten, and niobium can be applied to the present invention based on the following examination results.

Mo: Excluding ⁹⁸ Mo (24.1%), ⁹² M
The isotope ratio is adjusted to one component or two or more multicomponents of o, ⁹⁴ M, ⁹⁵ M, ⁹⁶ Mo, ⁹⁷ M, and ¹⁰⁰ Mo. W: Excluding ¹⁸⁴ W (30.3%) and ¹⁸⁶ W (28.6%),
^The isotope ratio is adjusted to one component or multiple components of ¹⁸⁰ W, ¹⁸² W, and ¹⁸³ W. Ta: Unadjustable (secondary radioactivity cannot be suppressed) Nb: Unnecessary (secondary radioactivity is not generated).

In ion implantation in an actual plant, it goes without saying that the selection of the element to be implanted and the adjustment ratio of its isotope are determined by comparing the effect with the investment amount. Even if harmful isotopes that generate secondary radioactivity by crystallization are not necessary to be completely removed 100%.

Finally, (4) the means and action for suppressing the growth of the oxide film itself, which is the site for incorporating radioactivity, by adjusting the water quality will be described.

It is generally known that the corrosion of steel materials is reduced by increasing pΗ. This is described in detail in the Stainless Steel Handbook (edited by Masayoshi Hasegawa, published by Nikkan Kogyo Shimbun, December 25, 1980, first edition, 8th edition, p297). According to this, it is stated that all reports agree that a high pΗ has the effect of improving the adhesion of corrosion products and reducing the release into water and the redeposition of products. Although it is widely recognized that a water environment with a high pΗ is effective against the corrosion of materials, it is not necessary to blindly raise the pH. Since the adhesion of the product to the heat transfer surface is the most disliked in both boilers and reactors, it is preferable to increase pH, but how to prevent alkali cracking etc.
The issue is whether to increase H. "

Considering, for example, in a nuclear power plant, this is because in a reactor type in which a boiling phenomenon occurs on the surface of the fuel clad tube, a concentration phenomenon occurs at that portion, and therefore the water quality environment of the fuel clad tube is cooled by increasing the pH. This is pointed out because the pH condition is extremely higher than the pH in the material and there is a risk of damage due to alkali cracking or the like.

Therefore, the present inventors have paid attention to the pH value published in the water quality data during the operation of the nuclear power plant, and have accumulated a huge amount of accumulated correlations between the pH value and the examples of damage to the fuel cladding. It was concluded that the BWR had no effect on the integrity of the fuel cladding if the pH of the coolant was at least 8.6 in terms of 25 ° C in alkaline water conditions. Of course, this pH value is for the current fuel cladding material, and needless to say, the adoption of a cladding tube that is more resistant to alkali corrosion will gradually increase the allowable range of application to higher pH.

By the way, in the case of BWR as an example, the water quality of the coolant is slightly shifted to the acidic side by the soluble chromium (at a level of several 10 ppb) existing at the highest concentration.
Therefore, in the present invention, by adding a reagent showing alkalinity,
It is intended to correct this deviation from neutrality and to change to weak alkaline water quality. As the reagent to be used, various kinds of alkali metals (Li, Na, K, Rb, Cs, Fr) and alkaline earth metals (Ca, Sr, Ba, Ra, Be, Mg) corresponding to the ion equivalent concentration of soluble chromium are used. At least one or more of the group consisting of compounds containing one or both of hydrogen and oxygen, such as hydroxides, hydrides, oxides, and metal acid salts, is applicable. Further, it is more desirable that the injected isotope ratio of the alkali metal or alkaline earth metal is adjusted so that secondary radioactivity due to activation does not occur even in the irradiation field of the core.

[0109]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the embodiment of the BWR of the primary cooling system for a nuclear reactor of the present invention will be described with reference to a main method for suppressing radioactive contamination, that is, electrolytic polishing is performed on a liquid contact portion of a coolant containing a radioactive substance. In addition, (1) Corrosion products containing iron clad as a main component, and those activated on the fuel surface,
Suppress the generation of so-called particulate radioactive materials, (2)
Corrosion products containing iron clad as a main component, and suppressing the adhesion of so-called particulate radioactive substances, which have been activated on the fuel surface, to the electrolytically polished surface (3) Ionic radioactivity incorporated in the oxide film Corresponding to the respective methods of suppressing the substance by the coexistence of metal ions and (4) suppressing the growth of the oxide film itself, which is the site for incorporating the radioactive substance, by adjusting the water quality, a description will be given with reference to the drawings. In addition, the same parts as those in FIG.
Duplicate description will be omitted.

First, (1) a corrosion product containing iron clad as a main component, and a method for suppressing the generation of so-called particulate radioactive substances, which are radioactiveized on the fuel surface, are applied to the practice of the present invention. The form will be described.

In a BWR plant as shown in FIG. 16, structural materials such as a reactor pressure vessel body, reactor internals, supply / condensation system piping and components, and reactor water recirculation, which come into contact with a coolant containing a radioactive substance. Electrolytic polishing of the liquid contact surface is applied to the piping and components of the system and the piping and components of the reactor water purification system for the purpose of suppressing the deposition of radioactive substances.

Furthermore, in order to more effectively suppress the adhesion of radioactive substances to the liquid contact surfaces of these structural materials, the parts where corrosion products are generated are the feed / condensation system, the reactor water purification system, and the reactor water recovery system. Metallic materials with a corrosion release rate of 1 mdm (mg / dm ² / month) or less at the respective operating environmental temperatures, such as stainless steel containing iron, chromium, or nickel as the main components, as materials for the circulation system piping and equipment wetted parts The amount of corrosion products generated is drastically reduced from the current level by using such as.

By the way, in the light water reactor using water as the heat transfer medium as described above, it is impossible to suppress the amount of corrosion products generated to zero by the existing technology. Therefore, a method is effectively used in which the particulate corrosion products generated and transferred into the coolant are collected by a filter and are not brought into the nuclear reactor to prevent conversion into radioactive corrosion products.

FIG. 1 schematically shows the structure of a filtration desalination filter suitable for recovering such particulate corrosion products. Reference numeral 31 is a structure called an element, which has a porous or mesh structure and is water permeable, and a crushed resin 33 is laminated on the outer surface thereof. The cross section of this filtration desalination filter is shown in FIG.

When a coolant containing particulate corrosion products is passed through the crushing resin 33 side through such a filter desalting filter, the corrosion products are trapped in the crushing resin 33 layer by the filtering phenomenon. In FIG. 2, reference numeral 35 indicates trapped particulate corrosion products.

When the filter desalting filter shown in FIG. 1 is used as a filter for recovering corrosion products, not only particulate corrosion products but also ionic impurities are trapped by the ion exchange reaction by the crushing resin 33. There is an effect.

As the filter for recovering the corrosion product, in addition to the above filter desalting filter, a hollow fiber filter having a macaroni structure, a ceramic filter or the like can be applied. With these filters, the size is 0.1 μm
The above particles can be efficiently recovered.

These recovery filters may be installed in one or more of the feed / condensation system, reactor water purification system and reactor water recirculation system of the BWR plant as shown in FIG. However,
Since the use temperature of the filtration desalination filter and the hollow fiber filter is 50 ° C. as a guide, the installation locations of these filters are limited to the condensate purification device 13 and the reactor water purification device 27. However,
For installation in other locations, once at 50 ° C
It goes without saying that there is no problem in using these after cooling the coolant.

On the other hand, although the ceramic filter varies depending on its type, it can usually be used at the reactor water temperature and can be applied to all the systems of the plant.

Next, (2) a method for suppressing the adhesion of corrosion products containing iron clad as a main component and so-called particulate radioactive substances, which are radioactiveized on the fuel surface, to the electrolytically polished surface An embodiment of the present invention will be described.

FIG. 3 shows a method in which the zeta potential of a particulate corrosion product is adjusted by changing its crystal form and crystal grain size to suppress the adhesion of the wetted member to the electrolytically polished surface. 1 shows an embodiment of a reactor primary cooling system of the present invention.

In this reactor primary cooling system, at the outlet side of the recirculation pump 17, the zeta potential of the particulate corrosion products and the zeta potential of the structural material subjected to the electrolytic polishing treatment are continuously measured. A measuring device 37 and a clad zeta potential adjusting device 39 for adjusting the zeta potential of the particulate corrosion product are installed. With these devices, the zeta potential of the corrosion product in the coolant is adjusted so that a repulsive force acts between the clad, which is a particulate corrosion product, and the structural material that has been subjected to the electrolytic polishing treatment. .

The clad zeta potential adjusting device 39 adjusts the zeta potential by adjusting the crystal form and crystal grain size of the clad. The crystal form of the clad can be changed by changing the temperature or the dissolved oxygen concentration. Further, the crystal grain size of the clad can be miniaturized by an ultrasonic vibration bath, while it can be grown by a physical action such as vibration or stirring, or by an increase in aging time or dissolved oxygen concentration.

The clad zeta potential adjusting device 39
Can be attached to the inlet side of the recirculation pump 17 or the final stage of the feed water heater 15. In addition, in an ABWR that does not have a reactor water recirculation system, it may be possible to install it separately in the reactor at the site where the clad circulates.

FIG. 4 shows an atom of the present invention to which a method of electrostatically suppressing the adhesion of particulate corrosion products by polarizing the structural material subjected to electrolytic polishing treatment and adjusting the zeta potential thereof. 1 shows an embodiment of a furnace primary cooling system.

In this reactor primary cooling system, zeta potential measurement is performed on the outlet side of the recirculation pump 17 for continuously measuring the zeta potentials of the particulate corrosion products and the electrolytically treated structural material. A device 37 and a structural material zeta potential adjusting device 41 for adjusting the zeta potential of the structural material subjected to electrolytic polishing treatment are installed. Here, it is configured assuming that the part where electropolishing is applied is the piping of the reactor water recirculation system, and while these plants are in operation, these devices are used and the zeta of the structural material that has been electropolished is applied. By adjusting the electric potential, a repulsive force acts between the clad and the structural material subjected to the electrolytic polishing treatment.

The method for adjusting the zeta potential of the structural material subjected to the electrolytic polishing treatment is, for example, in the case where it is a piping portion, the piping is insulated for each welding connection portion up to now, and the electrical polarization action is used. It is possible.

FIG. 5 schematically shows means for polarizing the pipe. In FIG. 5, reference numeral 43 denotes a target pipe, which is connected to an adjacent pipe 45 by a flange structure via a packing 47 having heat resistance and insulation. An electrode 49 serving as a counter electrode is installed at the center of the pipes 43 and 45. A lead wire is taken out from the outer surface of the electrode 49 and the target pipe 43, and is connected to the DC power supply 51.

The range of polarization for changing the zeta potential of the pipe is about ± 1 at the maximum with respect to the natural immersion potential which is a potential without electrical adjustment, and by limiting to this range, The risk of abnormal elution of piping material due to polarization can be minimized.

Further, by preliminarily adjusting the zeta potential of the structural material that comes into contact with the cooling material before use, it is possible to electrostatically suppress the adhesion of the particulate corrosion products.

As already described with reference to FIG. 25, the zeta potential of the metal material is lower than that after the oxide film is formed in the situation where the oxide film is not present and the metal surface is exposed. Therefore, the adherence of particulate corrosion products may increase during the period when the oxide film is not formed. In addition, on the metal surface that has been subjected to electrolytic polishing treatment, there is a risk that the adhesion of particulate corrosion products will be accelerated compared to the untreated material, and in order to avoid this as well, the electrolytic polishing surface is preliminarily attached. Apply an oxide film.

FIG. 6 schematically shows a means for carrying out a pre-oxidizing treatment in advance at the environmental temperature of the target liquid contact member at a place different from the service place. In FIG. 6, reference numeral 53 is a high-temperature high-pressure water supply device, and the high-temperature high-pressure water supply device 53 uses a pump 55 to supply the high-temperature high-pressure water to the target liquid contact member 57. The high-temperature high-pressure water is sent to the liquid contact member 57 that comes into contact with the coolant containing radioactivity during use by using various attachments. The water quality of the high-temperature high-pressure water is monitored by the water-quality measuring device 61 by continuously collecting a part of the water of the high-temperature high-pressure water supply device 53 using the pump 59.

It is desirable that the temperature of the high-temperature high-pressure water is equal to or higher than the environmental temperature at which each wetted member 57 is used, but 250 ° C. or higher is considered sufficient. Also, the processing time is at least 500
When the time is longer than that, it is expected that a corrosion oxide film having the required performance is produced. On the other hand, as for the quality of treated water, ultrapure water containing no impurities is the most desirable.
An electric conductivity of 1 μS / cm or less in terms of ° C is acceptable.
By the way, dissolved oxygen has a great influence on the production rate of an oxide film and its properties. It is considered that the higher the dissolved oxygen concentration in the buried water is, the more preferable it is, but if the concentration is 1 ppm or more, it is considered that there is no great difference in the characteristics of the oxide film formed.

The pre-adjustment of the zeta potential of the electropolished surface can also be achieved by attaching the target liquid contact member to the service site and then performing a circulation operation to use Joule heat or a heating device of a circulation pump. .

FIG. 7 shows that an oxide film is applied to the piping of the reactor water recirculation system of the current BWR shown in FIG. 16 and the liquid contact portion of the component equipment, and the piping of the reactor water purification system and the liquid contact portion of the component equipment. The method to do is shown typically. Here, it is assumed that these pipes have already been electrolytically polished.

The oxide film applying treatment is carried out by the following procedure. First, the steam system and the feed / condensation system are isolated from the reactor before the fuel is loaded. The recirculation pump 17 and the reactor water purification system pump 21 are activated to start the circulation operation of the reactor water. In this example, the Joule heat of the recirculation pump 17 is expected to raise the reactor water temperature to about 280 ° C.
During the formation of the oxide film, impurities and the like eluted from the wetted part material are purified by the reactor water purification system.

By setting the treatment time for the purpose of applying the above oxide film to at least 500 hours or more, it is expected that a corrosion oxide film having the required performance is produced. On the other hand, as the water quality condition of the treated water, ultrapure water containing no impurities is most preferable, but it is acceptable if the electric conductivity at 25 ° C. is 1 μS / cm or less. Furthermore, it has already been mentioned that there is no great difference in the characteristics of the oxide film formed if the dissolved oxygen concentration in the treated water is 1 ppm or more.

By the way, in such an oxide film application process, it is expected that dissolved oxygen in the treated water will be rapidly consumed as the oxide film is formed in the liquid contact member. Therefore, in order to deal with this, various preparations such as injection of ultrapure water containing a high concentration of dissolved oxygen and injection of oxygen gas are prepared in advance.

Next, an embodiment of the present invention will be described in which (3) a method of suppressing an ionic radioactive substance taken into an oxide film by the coexistence of metal ions is applied.

Here, in the process in which the ionic radioactive substance is taken into the corroded film of the structural material due to the corrosion of the wetted part, the uptake rate of these radioactive ions is
Taking advantage of the fact that it is dominated by the competitive reaction with the coexisting metal ion species, the metal ion species is actively added to suppress the attachment of radioactive ions. At that time, the isotope ratio of the metal ion species to be injected is adjusted to ensure the most effective ion injection so that secondary radioactive materials are not generated even when brought into the reactor. .

FIG. 8 shows an embodiment of the primary cooling system of the present invention in which isotope ratio-adjusted metal ions are injected into the coolant. 63 is attached, and a metal ion implanting device 65 for producing metal ions whose isotope ratio is adjusted and injecting into the coolant is connected to the downstream side of the reactor water purification device 27 via a valve 67.

An in-line ion chromatography device or the like is most suitable for the metal ion monitor 63.
According to this device, the metal ion concentration in the coolant can be measured at regular intervals.

The opening and closing of the valve 67 is controlled in accordance with the output of the metal ion monitor 63, and the amount of metal ions implanted from the metal ion implanter 65 is adjusted.

As the metal ion implantation device 65, for example, a device as shown in FIG. 9 is applied. This metal ion implanter uses a plurality of metal plates 69 made of a metal element having a desired isotope ratio adjusted or a metal plate 69 including a part thereof, and a DC voltage is applied between them to cause metal reaction by an electrode reaction. It is configured to generate ions.

In this metal ion implanter, first, the electrolyte is used as an electrolyte so that metal ions are easily generated by the electrode reaction. This is because if the electrolytic solution is an electrolyte, an electrolytic reaction occurs at a low voltage, so that the DC power supply equipment can be made compact. Therefore, as shown in FIG. 9, a carbon dioxide gas saturation tank 71 for converting the electrolytic solution into an electrolyte is provided.

A constant amount of pure water is continuously supplied from the pure water supply line 73 to the carbon dioxide gas saturation tank 71 through the flow rate adjusting valve 75. Carbon dioxide gas is supplied to the carbon dioxide gas saturation tank 71 from a carbon dioxide gas cylinder 77 through a bubbling line 79. As a result, the solution in the carbonation tank 71 and dissolved carbon dioxide, the following dissociation reaction _{CO 2 + Η 2 O → H} 2 CO 3 Η 2 CΟ 3 → Η + + ΗCO 3 - ΗCΟ 3 - → H + + CΟ 3 ^2- Produces an electrolyte and facilitates electrode reaction. The excess carbon dioxide gas is released from the seal pot 81 to the outside of the system.

A solution in which carbon dioxide gas is dissolved and carbonate ions are in a dissociated state is sent to the electrolytic cell 85 through the connecting pipe 83,
The electrode reaction is performed here. A metal plate 69 whose isotope ratio is adjusted is installed as an electrode in the electrolytic cell 85. In FIG. 9, it is composed of two metal plates 69, but a plurality of metal plates 69 are set to increase the generation amount, or electrodes made of different metal species are attached, and different ion species are blended. It can also be generated. These metal plates 6
A direct current flows between 9 through the DC power supply 87. When the polarity of the DC voltage applied between the metal plates 69 is switched at regular intervals to equalize the thinning of the metal plates, it is possible to effectively use the material.

The electrolytic solution in which the metal ions are dissolved is sent to the carbon dioxide gas removal tank 91 through the connecting pipe 89 in order to remove the dissolved carbonate ions. In the carbon dioxide gas removal tank 91, the degassing gas is supplied from the cylinder 93 via the bubbling line 95. Then, the dissolved carbonate ions are recovered in a gas state by the reverse reaction of the dissociation reaction. The recovered carbon dioxide gas and excess degassed gas are removed to the outside of the system by the seal pot 97. The tip portion of the bubbling line 95 has a bubbler structure having a large number of minute blowout ports so that degassed gas can be injected efficiently.

The metal ion solution thus produced is poured into the target site by the pouring pump 99.

By the way, Japanese Patent Publication No. 3-14155 described above describes a method of injecting metal ions by filling a tank with metal ions and then injecting them with a pump if necessary. . Further, as an example, Cr ion implantation is described, and it is described that Cr ions are filled in a tank. However, it is not possible to pack the chromium metal in an ionic state and at a high concentration so as to cope with plant-scale injection unless the pH of the solution in which Cr is dissolved is extremely acidic. Therefore, when this method is adopted, the acidic solution is introduced into the plant along with the injection of the ionic species.
The ion species to be introduced differ depending on what kind of acidic solution is used, but general anion species such as chloride ion, sulfate ion, nitrate ion, etc. threaten the soundness of structural materials and cause SCC (stress corrosion cracking). ) Is widely known to be an acceleration factor. In any case, implantation other than the target metal ion is not preferable.

In this embodiment, since the metal ion species to be injected are injected while being manufactured, the concentration in the tank is low, and the carbonate ions in the electrolytic solution are removed by degassing, so that unnecessary ion species are introduced. Is suppressed and only the target metal ions are implanted.

Other than Cr, Vg, V, Τi, Cu, Ni,
Concerning Zn and Cd as well, there is a concern that incidental injection of anion species may occur in the method of storing in the tank.

Due to the degassing of carbon dioxide gas, some of the dissolved metal ions are precipitated in the solution as particulate hydroxides. However, when these fine particles are brought into high temperature water, they become ionic state again. This is because the solubilities of these metals are sufficiently high compared to the target concentration (eg, 10 ppb), and as a result, there is no need to bring unwanted ionic species into the reactor, It is possible to achieve the purpose of.

In the above metal ion injecting apparatus, a metal ion species whose target isotope ratio is adjusted is used as a metal plate consisting of a single metal element or a metal plate containing a part thereof, and a DC voltage is applied. By using this for injection, it becomes possible to control the metal ion species concentration arbitrarily and delicately by adjusting the current value, and prevent the inflow of unnecessary metal ion species. it can. Furthermore, it is possible to easily mix the implanted ion species by changing the implanted ion species by replacing the electrode plate or by using a plurality of types of metal plates for the electrode plate. Of course, by increasing the number of electrode plates, injection from a laboratory scale to an actual plant scale is possible.

As described above, by using the metal ion pouring device 65 as shown in FIG. 9, the metal ion concentration in the reactor water can be maintained at a predetermined value in the embodiment shown in FIG. .

In this embodiment, the metal ion implanting device 65 is installed at the outlet of the reactor water purifying device 27. However, it is not limited to this position, and high-temperature water having the same temperature as the reactor water temperature flows. It can also be installed in existing parts (for example, a reactor water recirculation line, a water supply line, etc.) and a low temperature system such as the outlet of the condensate purification device 13.

FIG. 10 shows another example of the metal ion implanting apparatus. In order to generate a metal ion having a desired isotope ratio adjusted, a target element is brought into a metal state,
1 schematically shows a metal ion implanter installed in a high-temperature system of a primary cooling system to allow high-temperature water to pass therethrough and obtain a predetermined concentration by a corrosion release reaction.

In this figure, a cylindrical column 101 is filled with fine metal particles 103, and high temperature water is passed through this. For example, hot water from the high temperature system of the primary cooling system
It is introduced via 05 and passes through a column 101 packed with metal particles 103.

As a result, a corrosion release reaction occurs on the metal surface, and metal ions are released into high temperature water. The metal particles 1
03 is sized so as to have a distribution of 0.1 to 1 mm to increase the specific surface area and improve the packing density in the column 101. The metal particles in the column 101 are held by the screen 107.

By passing through the column 101, the high temperature water containing the target metal ions passes through the valve 109 and is returned to the high temperature system of the primary cooling system again. In addition, a bypass line 111 is also installed in the column 101 so that high temperature water can be bypassed via a bypass valve 113.

Further, the valves 109 and 111 have a flow rate adjusting function, and are configured to constantly adjust the opening while monitoring the metal ion concentration in the coolant by the metal ion monitor device 63. That is, when the metal ion concentration is lower than the predetermined value, the bypass valve 113 is throttled to increase the flow rate of the column 101. On the other hand, when it is higher than the predetermined value, the flow rate passing through the column 101 is narrowed down to reduce the metal ion generation amount.

Further, it is also possible to generate a predetermined metal ion by filling the column 101 with a finely divided oxide instead of the fine metal particles 103, and setting it in a high temperature system to pass high temperature water. When an oxide is used, it is sintered at a temperature of at least half of the melting temperature of the oxide to be in a sintered state, and the sintered state is maintained even when high-temperature water is passed through. Will not flow into the high temperature system by mistake, which makes it easy to maintain the high temperature system.

Furthermore, in the case of using fine metal particles or oxides to generate a desired metal ion whose isotope ratio is adjusted, the device configuration is simple, and before the actual use, the metal or By reducing the amount of impurities contained in the oxide, unnecessary ionic species that are incidentally introduced can be easily prevented.

FIG. 11 shows another embodiment of the primary cooling system of the present invention, in which isotope ratio-adjusted metal ions are injected into the coolant, and the target metal is made into fine particles. It is applied to a metal ion or an oxide state, which is installed in a high temperature system to allow high temperature water to pass therethrough to obtain a predetermined concentration of metal ion whose isotope ratio is adjusted by a corrosion release reaction. In addition, in this embodiment, the flow rate adjustment valve 10 as shown in FIG.
This is done by adjusting the flow rate of the high-pressure pump 115, regardless of whether it is 9 or 113.

In FIG. 11, a column 101 is filled with fine particles or oxides of a target metal in order to generate a target metal ion having an adjusted isotope ratio. This column 101 has both valves 105,
Open 117 and connect to the recirculation line. The high-pressure pump 115 compensates the pressure loss generated in the column 101 and adjusts the flow rate of the column 101.

With such an apparatus configuration, the flow rate flowing through the column 101 is adjusted by the output of the metal ion monitoring device 63 for monitoring the metal ion concentration in the reactor water to achieve the predetermined metal ion concentration in the reactor water.

In this embodiment, the metal ion implanter is installed in the recirculation line on the upstream side of the recirculation pump 17. Of course, the position is not limited to this position, and high-temperature water at the same temperature as the reactor water temperature is used. It can be installed in the part where the water flows (downstream of the recirculation pump, water supply line, reactor water purification system outlet, etc.).

FIG. 12 shows still another example of the metal ion implanting apparatus. In order to generate a target metal ion, a target metal element other than an oxide is replaced with a hydride or a hydroxide. Further, a metal ion implanter for obtaining a predetermined concentration by injecting into a coolant in a slurry state or a solution state in a compound state containing one or both of hydrogen and oxygen like a metal acid salt is schematically shown. There is.

In FIG. 12, first, pure water supply line 1
Pure water is continuously supplied from 19 to the suspension tank 121. Above the suspension tank 121, a tank 123 filled with a hydride or a hydroxide, or a compound containing hydrogen or oxygen or both such as a metal salt in a fine powder state is installed. ing. The fine powder in the tank 123 is continuously or intermittently supplied to the suspension tank 121. A forced stirring means such as an impeller 125 is attached to the suspension tank 121 to prevent the fine powder from settling.

The slurry-like suspension or solution is injected at a predetermined point by the high pressure pump 127. These injected slurries are rapidly metal ionized by contact with high temperature water.

FIG. 13 shows still another embodiment of the primary cooling system of the present invention, in which isotope ratio-adjusted metal ions are injected into the coolant. In addition to oxides, hydrides or hydroxides, and even metal salts such as hydrogen and oxygen, or a compound state containing both, are injected into the coolant in a slurry state or a solution state, and isotopes are introduced. The method of obtaining the predetermined concentration of the metal ion whose ratio is adjusted is applied.

In this embodiment, while monitoring the metal ion concentration in the reactor water with the metal ion monitor device 63, a suspension tank in which a particulate compound having a desired isotope ratio adjusted is suspended in a slurry. The suspension of 121 is injected into the water supply line of the plant by the high pressure pump 127.

In this system, the flow rate of the high pressure pump 127 is adjusted by the output of the metal ion monitor device 63 to achieve a predetermined metal ion concentration in the coolant.

In this embodiment, the metal ion implanter is installed in the water supply line, but it is not limited to this position, of course, and a portion where hot water having a temperature similar to the reactor water temperature flows (reactor water recirculation). It can be installed at the line, reactor water purification system outlet, etc.). In addition, in a part where the flow rate is large in each part of the plant and settling in the line can be ignored, there is no problem in installing not only in the high temperature system but also in the low temperature system.

By the way, all the above-mentioned embodiments describe the boiling water nuclear power plant of the type in which the reactor water is forcedly circulated by the jet pump.
The reactor type is not limited to this. A natural circulation type boiling water nuclear power plant without a jet pump, an ABWR that does not have an external recirculation line and forcibly circulates reactor water by an internal pump, Can also be applied to all light water reactors and heavy water reactors including pressurized water nuclear power plants (PWR).

Finally, an embodiment of the present invention will be described in which (4) a method of suppressing the growth of the oxide film itself, which is a radioactive substance uptake site, by adjusting the water quality is applied.

FIG. 14 schematically shows an alkali injecting device for injecting an alkali metal ion or an alkaline earth metal ion into the secondary coolant in order to suppress the corrosion of the wetted member subjected to the electrolytic polishing treatment. ing.

In FIG. 14, first, pure water supply line 1
Pure water is continuously supplied to the tank 131 from 29. A tank 133 filled with an alkali metal salt or an alkaline earth metal salt in a fine powder state is installed above the tank 131. The fine powder in the tank 133 is continuously or intermittently supplied to the tank 131. A forced stirring means such as an impeller 135 is attached to the tank 131 to promote the dissolution of the fine powder.

These solutions are injected at a predetermined point by the high pressure pump 137. Further, in order to measure the concentration of alkali metal ions or alkaline earth metal ions in the tank 131, a part of the tank water is sampled and introduced into the water quality measuring device 141 using the pump 139 for monitoring.

The water quality measuring device 141 is most preferably equipped with a device capable of measuring the absolute concentration of alkali metal ions or alkaline earth metal ions, but in the case where the target ion species is limited. Can be substituted with only a pH meter or a conductivity meter.

FIG. 15 shows the primary cooling of the present invention in which the alkali injecting apparatus as described above is applied to suppress the corrosion of the liquid-contacting member subjected to the electrolytic polishing treatment and to suppress the adhesion of the ionic radioactive substance. 1 shows an embodiment of a system.

In FIG. 15, the alkali injecting device 143 is used.
Is installed on the downstream side of the condensate purification device 13 via the high-pressure pump 137, but it can be installed in each system of the supply / condensation system, the reactor water recirculation system, and the reactor water purification system other than this position. .
Further, in order to measure the soluble chromium concentration in the coolant, a chromium concentration measuring device 145 is attached to the reactor water recirculation system. The installation location of the chromium concentration measuring device 145 is not limited to the reactor water recirculation system, and may be the reactor water purification system, as long as the coolant can be taken out from the system. .

As the chromium concentration measuring device 145, the most suitable is ion chromatography capable of continuous measurement in the current equipment. Although the accuracy is lowered, a pΗ meter, which is usually attached to measure the pΗ of reactor water, can be used as a substitute for this device to some extent. However, when the pΗ meter is used, it is a prerequisite that the main impurity in the coolant is a soluble chromium plant.

Using a high pressure pump 137 from the alkali injecting device 143, a predetermined amount is adjusted so as to match the soluble chromium concentration measured by the chromium concentration measuring device or the ion equivalent of the chromium concentration estimated from the value of the p meter. A concentration of alkali metal ions or alkaline earth metal ions is injected to maintain the coolant pΗ neutral or weakly alkaline.

As means for injecting alkali metal ions or alkaline earth metal ions into the primary cooling system of the reactor, in addition to the alkali injecting device shown in FIG. 14, the existing desalting device is used in the primary cooling system. These can be introduced.

That is, in the BWR plant as shown in FIG. 16, the condensate purification device 13 and the reactor water purification device 27
Is composed of a plurality of desalting towers in which a cation exchange resin and an anion exchange resin are filled at a predetermined ratio.
In a plant consisting of a filter desalting device in which the Yin and Yang ion exchange resins are crushed and then stacked, or a combination of both, alkali metal ions or alkaline earth metal ions are added to these. It is possible to preliminarily give the whole or a part of the cation exchange resin by an ion exchange reaction so that the cation exchange resin is dropped from the ion exchange resin by a water-passing operation and brought into the primary cooling system.

For example, the following formula R ⁻ + Na ⁺ → R-Na indicates a state in which sodium ion (Na ⁺ ) which is one of alkali ions is attached to the cation exchange resin (R ⁻ ) by an ion exchange reaction. There is.

As described above, the cation exchange resin to which sodium ions are attached does not permanently take in the sodium ions, but releases the sodium ions into the solution when contacted with an ionic species having a larger charge than the sodium ions. Further, due to the deterioration of the ion exchange resin, it becomes difficult for the ion exchange resin to retain the reactive group, and there is a gradual elution amount. By these processes, it is released to the primary cooling system.

The ion exchange resin is reused by performing a regenerating operation when its ion exchange capacity is lowered. Generally, a hydrochloric acid solution is used for the cation exchange resin, and a sodium hydroxide solution is used for regenerating the anion exchange resin. However,
In the regeneration process of the mixed bed type desalination equipment consisting of anion and cation ion exchange resin, the separation of both ion exchange resins cannot be performed completely, and therefore the sodium ion of the sodium hydroxide solution used for regeneration of the anion exchange resin However, there is always a situation where it adheres to a cation exchange resin mixed in in a trace amount and is used as it is. These sodium ions are gradually released by the water flow operation and supplied into the primary coolant. That is, in a plant in which the condensate water purification device 13 and the reactor water purification device 27 are composed of a mixed bed type desalination device, the cation exchange resin is intentionally treated with an alkaline solution by periodically performing the regeneration operation. The purpose can also be achieved without applying ions.

The present invention is installed not only in a nuclear power plant, but also in a facility that handles radioactive substances (for example, a nuclear fuel reprocessing facility), in which a flow path of a solution containing a radioactive substance flows, and further in the flow channel. It can also be applied to the technology for suppressing the adhesion of radioactive substances to the structural materials and equipment that have been created.

[0191]

As described above, according to the present invention, by further performing the treatment from the following viewpoints together with the electropolishing treatment, a further effect of suppressing radioactivity can be obtained.

(1) Corrosion products containing iron clad as a main component and generation of so-called particulate radioactive substances, which were activated on the fuel surface, were selected by selecting the material of the member. We have implemented a method to regulate the amount of generation itself at the generation site and a method to prevent the generated particulate corrosion products from being brought into the reactor by installing a recovery filter. Control radioactive contamination. In addition, corrosion products containing iron clad as a main component, and so-called particulate radioactive substances that have been activated on the fuel surface are attached to the corrosion products containing iron clad as a main component and the electrolytically polished surface. It suppresses by adjusting so that repulsive force works mutually and repel each other.

[0193] As a result, not only the incorporation of the particulate radioactive material, which had a possibility of offsetting the effect of suppressing the adhesion of the ionic radioactivity by the electropolishing, could be suppressed, but also the oxide film at the initial stage of the plant operation. The risk of increased adhesion of particulate corrosion products during the period when the
Furthermore, it is possible to avoid the risk of accelerating the adhesion of particulate corrosion products on the metal surface subjected to the electrolytic polishing treatment, as compared with the case where the metal surface is not treated.

(2) A corrosive oxide film, which is a radioactive attachment site, is formed even under water conditions where the removal of particulate radioactive substances can be expected to effectively prevent the adhesion of ionic radioactive substances. The phenomenon of uptake of ionic radioactive substances into here still occurs. Therefore,
In the present invention, in the process in which ionic radioactive substances are taken into the corroded film along with the corrosion of the wetted part of the structural material, the rate of uptake of these radioactive ions depends on the competitive reaction with the coexisting metal ion species. Taking advantage of the fact that it is dominated, the amount of ionic radioactivity incorporated can be suppressed by positively adding the metal ion species. Further, in the present invention, the isotope ratio of the metal ion species to be injected is adjusted, and only the specific isotope metal ion species is injected, so that the generation of secondary radioactivity is prevented and the most effective metal ion species is obtained. Can be poured.

(3) Paying attention to the pH value published in the water quality data during operation of the nuclear power plant, verifying the enormous accumulated data regarding the correlation between the pH value and the damage example of the fuel cladding tube However, even in a furnace type where boiling occurs on the surface of the fuel cladding, problems such as alkali cracking do not occur.
By finding the conditions, it is possible to suppress the growth itself of the corrosion oxide film, which is a site for attaching radioactivity, by the high pH water quality, and reduce the amount of ionic radioactive substance taken up.

[Brief description of the drawings]

FIG. 1 is a perspective view of a filtration desalination filter showing an example of a recovery filter suitable for the present invention.

FIG. 2 is a cross-sectional view showing a partially enlarged view of the filtration desalination filter of FIG.

FIG. 3 is a diagram showing an embodiment of a reactor primary cooling system of the present invention.

FIG. 4 is a diagram showing an embodiment of a reactor primary cooling system of the present invention.

FIG. 5 is a diagram showing a means for polarizing the pipe according to the present invention.

FIG. 6 is a diagram showing an example of means for performing pre-oxidation treatment on the liquid contact member according to the present invention in advance.

FIG. 7 is a diagram schematically showing a method of applying an oxide film to a pipe of a reactor water recirculation system and a liquid contact part of a component, and a pipe of a reactor water purification system and a liquid contact part of a component.

FIG. 8 is a diagram showing an embodiment of a primary cooling system of the present invention in which isotope ratio-adjusted metal ions are injected into a coolant.

FIG. 9 is a diagram showing an example of a metal ion implantation apparatus according to the present invention.

FIG. 10 is a diagram showing another example of the metal ion implantation apparatus according to the present invention.

FIG. 11 is a view showing another embodiment of the primary cooling system of the present invention in which isotope ratio-adjusted metal ions are injected into the coolant.

FIG. 12 is a diagram showing still another example of the metal ion implantation apparatus according to the present invention.

FIG. 13 is a diagram showing still another embodiment of the primary cooling system of the present invention, in which isotope ratio-adjusted metal ions are injected into the coolant.

FIG. 14 is a view showing an example of an alkali injection device according to the present invention.

FIG. 15 is a diagram showing an embodiment of a primary cooling system of the present invention to which an alkali injection device is applied.

FIG. 16 is a diagram showing a general example of a primary cooling system of a boiling water reactor.

FIG. 17 is a diagram showing the structure of a test body used for a radioactivity adhesion test.

FIG. 18 is a diagram showing the arrangement of test bodies in a radioactivity adhesion test.

FIG. 19 is a diagram showing a result of a radioactivity adhesion test in an environment without an iron clad.

FIG. 20 is a diagram showing a result of a radioactivity adhesion test in an environment where iron clad coexists.

FIG. 21 is a diagram showing the time change of the increase in radioactivity due to the adhesion of the iron clad.

FIG. 22 is a diagram showing changes in zeta potential of iron clad added in the radioactivity adhesion test with pH.

FIG. 23 is a diagram showing changes in zeta potentials of two types of test pieces for radioactivity adhesion test (one subjected to electrolytic polishing treatment and one not subjected to electrolytic polishing treatment) depending on pH.

FIG. 24: p on electropolished surface and untreated surface at 25 ° C.
It is a figure which shows the change of the iron clad adhesion amount by H.

FIG. 25 is a diagram showing a time change of each zeta potential of the test piece a subjected to the pre-oxidation treatment and the test piece b not subjected to the pre-oxidation treatment.

FIG. 26 is a diagram showing changes in zeta potential of various iron oxides depending on pH.

FIG. 27 is a diagram showing changes in zeta potential of hematite having different crystal grain sizes depending on pH.

[Explanation of symbols]

 1 Reactor pressure vessel 3 Reactor core 5 Steam line 7 Turbine 9 Condenser 13 Condensate purifier 15 Feed water heater 17 Recirculation pump 19 ……… Jet pump 21 ……… Reactor water purification system pump 27 ……… Reactor water purification device 31 ……… Element 33 ……… Crushing resin 37 ……… Recirculation pump 39 ……… Clad zeta Potential adjusting device 41 ………… Structural material zeta potential adjusting device 43, 45 ………… Piping 47 ………… Packing 49 ………… Electrode 51 ………… DC power source 63 ………… Metal ion monitor device 65 ………… Metal ion Injection device 121 ... Suspension tank 143 ... Alkaline injection device 145 .... Chromium concentration measurement device

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G21D 1/00 GDBX

Claims (30)

[Claims] 1. A method for suppressing radioactive contamination of a member that comes into contact with a radioactive fluid, wherein the liquid contact surface of the member is subjected to electrolytic polishing in advance, and the amount of corrosion released per month of the member at ambient temperature. A method for suppressing radioactive contamination, which comprises forming a metal material having a concentration of 1 mg / dm ² or less. 2. In the radioactive fluid in contact with the member,
The method for suppressing radioactive contamination according to claim 1, wherein particulate matter having a size of 0.1 μm or more is removed. 3. A method for suppressing radioactive contamination of a member that comes into contact with a radioactive fluid, wherein the liquid contact surface of the member is subjected to electrolytic polishing in advance, and the zeta potential of the liquid contact surface and the particulate matter in the radioactive fluid. Radioactive contamination characterized by adjusting at least one of the zeta potentials so as to reduce the difference from the zeta potential of the substance to electrostatically suppress the adhesion of the particulate matter to the liquid contact surface. Suppression method. 4. The method for suppressing radioactive contamination according to claim 3, wherein the zeta potential of the liquid contact surface of the member is adjusted by polarizing the member. 5. The method for suppressing radioactive contamination according to claim 3, wherein the zeta potential of the liquid contact surface of the member is adjusted by previously forming an oxide film on the liquid contact surface. 6. The wetted surface is exposed to high temperature water of 250 ° C. or higher 500
The method for suppressing radioactive contamination according to claim 5, wherein an oxide film is formed by contacting for more than a time. 7. The high temperature water has an electric conductivity of 1 at 25 ° C.
7. The method for suppressing radioactive contamination according to claim 6, wherein the dissolved oxygen concentration is 1 μS / cm or less and the dissolved oxygen concentration is 1 ppm or more. 8. The method for suppressing radioactive contamination according to claim 3, wherein the zeta potential of the particulate matter in the radioactive fluid is adjusted by changing the crystal form of the particulate matter. 9. The method for suppressing radioactive contamination according to claim 3, wherein the zeta potential of the particulate matter in the radioactive fluid is adjusted by changing the particle size of the particulate matter. 10. A method for suppressing radioactive contamination of a member that comes into contact with a radioactive fluid, wherein the liquid contact surface of the member is preliminarily subjected to electrolytic polishing, and a radioactive nuclide is secondarily generated even when subjected to activation. A method for suppressing radioactive contamination, which comprises injecting metal ions whose isotope ratio is adjusted so as not to do so into the radioactive fluid. 11. The metal ions whose isotope ratio is adjusted are Mg except for Mg-26 and Cr and V except for Cr-50.
V excluding -51, Ti excluding Ti-50, Ni-58, N
Ni, Zn-64, Zn- except i-62 and Ni-64
Zn excluding 68 and Zn-70, C excluding Cd-114
11. At least one selected from the group consisting of d, Mo excluding Mo-98, W-184 and W excluding W-186, and Nb, and the suppression of radioactive contamination according to claim 10. Method. 12. A method for suppressing radioactive contamination of a member that comes into contact with a radioactive fluid, wherein the liquid contact surface of the member is preliminarily electropolished, and the pH of the radioactive fluid is adjusted to alkali metal ions or alkaline earth metal ions. A method for suppressing radioactive contamination, which comprises adjusting to neutral or weakly alkaline by at least one of the above. 13. The radioactive fluid is injected with at least one of the alkali metal ion and the alkaline earth metal ion, which substantially correspond to the ion equivalent concentration of soluble chromium in the radioactive fluid. 1
2. The method for suppressing radioactive contamination according to 2. 14. The radioactive fluid has a pH at 25 ° C.
The method for suppressing radioactive contamination according to claim 12 or 13, characterized in that the method is adjusted to be 8.6 or less. 15. In a reactor primary cooling system in which the reactor primary coolant circulates, the liquid contact surface of the structural material in contact with the primary coolant is preliminarily subjected to electrolytic polishing, and 0.1 μm in the primary coolant is used. A reactor primary cooling system comprising at least one of a filter desalting filter, a hollow fiber filter and a ceramic filter for removing the above particulate matter. 16. The primary cooling system for a nuclear reactor according to claim 15, wherein the structural material is formed of a metal material having a monthly corrosion release amount of 1 mg / dm ² or less at an operating environment temperature. 17. A reactor primary cooling system in which a primary coolant of a nuclear reactor circulates, wherein a liquid contact surface of a structural material which comes into contact with the primary coolant is subjected to electrolytic polishing in advance and electrolytic polishing of the structural material is performed. Zeta potential measuring device for measuring the zeta potential of the liquid contact surface and the zeta potential of the particulate matter in the primary coolant, and the zeta potential for adjusting the zeta potential of the liquid contact surface or the zeta potential of the particulate matter. A primary cooling system for a nuclear reactor, comprising: a regulating device. 18. The reactor primary cooling system according to claim 17, wherein the zeta potential adjusting device adjusts the zeta potential of the particulate matter by changing its crystal form or crystal grain size. system. 19. The primary reactor cooling system according to claim 17, wherein the zeta potential adjusting device adjusts the zeta potential of the liquid contact surface by polarizing the structural material. 20. The zeta-potential adjusting device comprises a structural material that is insulated by inserting a packing for each connection portion, an electrode axially installed at the center of the inside of the structural material, the structural material and the electrode. 20. The primary cooling system for a nuclear reactor according to claim 19, further comprising: 21. In a reactor primary cooling system in which a reactor primary coolant is circulated, a liquid contact surface of a structural material that comes into contact with the primary coolant is electrolytically polished in advance, and this electrolytically polished liquid contact is performed. A primary cooling system for a nuclear reactor, characterized in that an oxide film is formed on the surface to previously adjust the zeta potential of the liquid contact surface. 22. The pure water having a conductivity of 1 μS / cm or less at 25 ° C. and a dissolved oxygen concentration of 1 ppm or more at 25 ° C. is contacted with the liquid contact surface at a temperature of 250 ° C. or more for 500 hours or more in advance, 22. The nuclear reactor primary cooling system according to claim 21, wherein an oxide film is formed. 23. In a reactor primary cooling system in which the reactor primary coolant circulates, the liquid contact surface of the structural material that comes into contact with the primary coolant is preliminarily electropolished and brought into the reactor. A metal ion implanter for injecting metal ions whose isotope ratio is adjusted so as not to generate secondary radionuclides into the primary coolant, and the concentration of the metal ions in the primary coolant. A primary cooling system for a nuclear reactor, comprising a metal ion monitoring device for monitoring and controlling the injection amount of the metal ions. 24. The metal ion implanting apparatus comprises a plurality of means for blowing carbon dioxide gas into pure water to generate an electrolytic solution, and a plurality of metal plates containing a metal element whose isotope ratio is adjusted in the generated electrolytic solution. A means for generating a metal ion whose isotope ratio is adjusted by immersing one plate and applying a DC voltage between these plates,
24. The primary cooling system for a nuclear reactor according to claim 23, further comprising: a carbon dioxide gas removing means for degassing carbon dioxide gas from the electrolytic solution containing the metal ions and supplying the carbon dioxide gas into the primary coolant. 25. The metal ion implanter passes high temperature water through a column packed with particles of a metal or oxide thereof whose isotope ratio is adjusted, and a high temperature containing metal ions released by a corrosion reaction. 24. The reactor primary cooling system of claim 23, including means for supplying water into the primary coolant at approximately the same high temperature. 26. The nuclear reactor primary cooling system according to claim 25, wherein the metal oxide is a sintered body that is fired at a temperature that is at least half the melting temperature of the metal oxide. 27. The nuclear reactor primary cooling system according to claim 25, wherein the high-temperature water is the primary coolant collected by a split flow. 28. The metal ion implantation apparatus cools the solution or slurry containing at least one compound selected from the group consisting of hydrides, hydroxides, and metal salts of isotope ratio-adjusted metal to the primary cooling. The reactor primary cooling system according to claim 23, further comprising means for supplying the material into the material. 29. The metal ions whose isotope ratio is adjusted are Mg except Mg-26 and Cr and V except Cr-50.
V excluding -51, Ti excluding Ti-50, Ni-58, N
Ni, Zn-64, Zn- except i-62 and Ni-64
Zn excluding 68 and Zn-70, C excluding Cd-114
29. At least one kind selected from the group consisting of Mo excluding d, Mo-98, W-184 excluding W-186, and W, Nb excluding W-186. 29. The primary reactor cooling system described in. 30. In a reactor primary cooling system in which a reactor primary coolant circulates, a liquid contact surface of a structural material that comes into contact with the primary coolant is preliminarily subjected to electrolytic polishing, and a chromium concentration in the primary coolant. Chromium concentration monitoring means for monitoring the, and at least one of alkali metal ions or alkaline earth metal ions to match the ion equivalent of the chromium concentration in the primary coolant based on the monitoring results of this chromium concentration monitoring means. A reactor primary cooling system, comprising: an alkali supply means for supplying the primary coolant.