JP2000097843A - Corrosion evaluation method for zirconium-series metal and zirconium-based alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corrosion evaluation method for a zirconium-series metal, excellent in water quality impact assessment, in material selection of the zirconium- series material for being used in a high-temperature water environment. SOLUTION: A zirconium-series metal is given an initial oxidation treatment comprising a prescribed-time heating treatment (single-step treatment) at a constant temperature in high-temperature water or in high-temperature water and steam by using test water having a dissolved oxygen quantity of 2-100 ppb, or a step-wise prescribed- time heating treatment (plural-step treatment) at prescribed temperatures in high- temperature water or in high-temperature water and steam by using test water having a dissolved oxygen quantity of 2-100 ppb, and thereafter given a high-temperature water treatment for heating as long as a prescribed time at an actual machine using temperature by using test water having the same dissolved oxygen quantity as the dissolved oxygen quantity of the actual machine. After cooling the metal once, the metal is treated in high-pressure steam at 490-510 deg.C for 120-240 hours, and evaluated by measurement of the thickness of an oxide film formed on the surface of the zirconium-series metal and by the existence of a local accelerated corrosion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the evaluation of corrosion resistance of zirconium-based metals used in fuel cladding tubes for nuclear power plants and the like, and more particularly to a method of evaluating corrosion of zirconium-based metals for predicting localized accelerated corrosion caused by water quality over a wide range. It relates to a zirconium-based alloy.

[0002]

2. Description of the Related Art Conventional methods for evaluating the corrosion of zirconium-based metals include a high-temperature water corrosion test in which the metal is immersed in high-temperature water for a long period of time, and a corrosion test in steam which corrodes in steam.

[0003] In the high-temperature water corrosion test, an initial oxidation treatment is not performed in an initial stage of the test, but rather, a predetermined temperature is reached in a short time to evaluate corrosion. Further, the corrosion test in steam is also stipulated to raise the temperature in a short time without performing the above-described initial oxidation treatment. Further, the corrosion test in steam has a drawback that the effect of water quality cannot be evaluated.

[0004] Recently, in actual products such as fuel cladding tubes for nuclear power plants, local accelerated corrosion frequently occurred in materials that passed the above corrosion test. It has been found that this is likely to occur when the manufacturing conditions and application conditions of the material are different from those in the related art. A test method capable of evaluating such materials has been required. In particular, a new corrosion evaluation method that can predict such unique localized accelerated corrosion is desired.

[0005] Conventional forms of corrosion are nodular corrosion which selectively progresses to a small area or uniform corrosion which progresses to the entire surface. ASTM G-2-74 and ASTM G-2-8 are examples of corrosion evaluation methods for selecting such materials.
0, ASTM B-353-95, etc., but there is no provision for the initial oxidation treatment in these corrosion test methods.

As a method for determining the corrosion resistance of a zirconium alloy, there is Japanese Patent Application Laid-Open No. 60-242342, but it is not possible to predict peculiar local accelerated corrosion in the same manner as described above.

[0007]

It has been pointed out that corrosion of zirconium and zirconium alloys is affected by water quality, but at present there is no quantitative evaluation test method.
As described above, the effect of water quality could not be evaluated by a simple corrosion test in steam, and in particular, it was not a quantitative evaluation test method.

[0008] A high-temperature water immersion test at an actual plant operating temperature is also an important test method, but its evaluation requires a long period of time.

It is an object of the present invention to provide a method for evaluating corrosion of a zirconium-based metal material in which local accelerated corrosion of a zirconium-based metal material is predicted in advance, and in particular, the influence of water quality can be evaluated.

[0010]

An initial oxide film of zirconium and a zirconium alloy is formed at an extremely low temperature, and the growth of the oxide film is continued by the subsequent corrosion in high-temperature water or steam. In the growth process of the oxide film, there is a transition point at which the oxide film rapidly grows at a certain point and turns into accelerated corrosion. The transition point differs depending on the material composition and the like, and the quantitative evaluation of the transition point is the basis of the corrosion evaluation. In particular, in the selection of materials, a corrosion evaluation method capable of evaluating the influence of water quality has been desired.

The basic principle of the present invention is that a low dissolved oxygen environment which intentionally promotes formation of an unstable film when forming an initial oxide film serving as a protective film of a zirconium-based metal material, and a protective oxide film which is formed thereafter Is made unstable by the addition of a reagent or the like, and the water quality sensitivity of the material is evaluated. The gist of the present invention is as follows.

[1] a. Heat treatment of a zirconium-based metal in high-temperature water or high-temperature water and steam using test water having a dissolved oxygen content of 2 to 100 ppb at a constant temperature for a predetermined time (single-step treatment), or a dissolved oxygen content of 2 to 100 pb
After an initial oxidation treatment in which high-temperature water or high-temperature water and water vapor using pb test water are heated in a stepwise manner at a predetermined temperature for a predetermined time (multi-step processing), b. The dissolved oxygen amount is the dissolved oxygen amount of the actual machine (about 150 to 400
high-temperature water treatment using the same test water as in ppb) and heating at the actual operating temperature for a predetermined time, measuring the thickness of the oxide film formed on the surface of the zirconium-based metal, and evaluating the presence or absence of local accelerated corrosion A corrosion evaluation method for zirconium-based metals, characterized by the following.

[2] a. Heat treatment of a zirconium-based metal in high-temperature water or high-temperature water and steam using test water having a dissolved oxygen content of 2 to 100 ppb at a constant temperature for a predetermined time (single-step treatment), or a dissolved oxygen content of 2 to 100 pb
After an initial oxidation treatment in which high-temperature water or high-temperature water and water vapor using pb test water are heated in a stepwise manner at a predetermined temperature for a predetermined time (multi-step processing), b. High-temperature water treatment using a test water having the same amount of dissolved oxygen as the amount of dissolved oxygen of the actual machine and heating at the actual machine operating temperature for a predetermined time; c. Once cooled, 490-510 ° C, 120
A method for evaluating the corrosion of a zirconium-based metal, which comprises treating the oxide film formed on the surface of the zirconium-based metal for up to 240 hours, and evaluating the thickness of the oxide film based on the presence or absence of localized accelerated corrosion.

[3] The test water used for the initial oxidation treatment is sodium chromate or sodium sulfate.
The method for evaluating corrosion of zirconium-based metals described above containing from ⁶ to 10 to ⁴ mol / l.

[4] The method for evaluating corrosion of zirconium-based metals as described above, wherein the single-step treatment is a treatment performed at a heating temperature of 80 to 150 ° C. for 5 to 50 hours.

[5] The multi-step process is performed in the range of 50 to 2
The above-mentioned method for evaluating corrosion of zirconium-based metals, wherein the temperature is raised stepwise in steps of 50 ° C to 50 ° C, and the holding time in each step is 5 to 50 hours.

[6] The high-temperature water treatment is performed at 280-340 ° C., 24 hours in high-temperature water or in two phases of high-temperature water and steam.
The above-mentioned method for evaluating corrosion of zirconium-based metals, which is maintained for up to 240 hours.

[7] The method for evaluating corrosion of zirconium-based metals according to [1], wherein electric resistance is measured instead of measuring the thickness of the oxide film.

[8] Sn: 1-2% by weight, Fe:
0.05 to 0.24%, Cr: 0.05 to 0.15%, N
i: In a zirconium-based alloy in which 0.03 to 0.10% and the balance is substantially Zr, the amount of dissolved oxygen is 80 ppb.
After heating for 24 hours at 80 ° C. and 3.9 MPa in high-temperature water, heating at pp. 288 ° C. and 6.9 MPa in high-temperature water for 200 hours at 200 ppb of dissolved oxygen, and then 200 ppb for dissolved oxygen
b. A zirconium-based alloy characterized in that the thickness of the oxide film after heating in steam of 500 ° C. and 10.3 MPa for 120 hours is 5.5 μm or less.

[0020]

[9] By weight, Sn: 1-2%, Fe:
0.05 to 0.24%, Cr: 0.05 to 0.15%, N
i: In a zirconium-based alloy in which 0.03 to 0.10% and the balance is substantially Zr, the amount of dissolved oxygen is 80 ppb.
At 50 ° C for 7 hours, 100 ° C for 14 hours, 150 ° C for 7 hours
After heating at 200 ° C. for 14 hours and at 250 ° C. for 7 hours in sequence with high-temperature water, the dissolved oxygen content was 2
It is heated at 88 ° C. and 6.9 MPa in high-temperature water for 216 hours, and then at 500 ° C. and 10.3 M at a dissolved oxygen amount of 200 ppb.
A zirconium-based alloy, wherein the thickness of the oxide film after heating in water vapor of Pa for 216 hours is 10 μm or less.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The corrosion evaluation method of the present invention will be described. As a test piece, a silconium cladding tube is cut into a round slice, and with respect to an inner zirconium liner tube, the liner layer is removed and the inner zirconium liner tube is rubbed with the outer diameter of the heater pin.
The sliding work between the test piece and the heater pin minimizes the gap between the two, so that the surface of the test piece is in the boiling range during the boiling field test.

The most important processing in the present invention is the initial oxidation processing, and includes a single-step processing shown in FIG. 1 and a multi-step processing shown in FIG.

The condition of the single-step initial oxidation treatment is 80 to 1
Hold at 50 ° C. for 5-50 hours. Note that the pressure of the atmosphere may be such that a high-temperature water environment can be maintained, but in the formation of a boiling field, it is set to the steam critical pressure at each temperature. The heating means may be external heating such as a preheater or internal heating using a heater pin.

The test water environment is desirably a circulation type, and the dissolved oxygen in the test water (pure water) is an important factor.
１００100 ppb is the basis.

The concentration of the added reagent in the water quality test is as follows:
The amount of sodium chromate (Na ₂ CrO ₄ ) or sodium sulfate (Na ₂ SO ₄ ) is preferably about 1 × 10 to ⁵ mol / l, whereby the initial oxide film of the test piece can be made more unstable. Corrosion sensitivity can be extracted with high sensitivity.

Next, the test piece on which the unstable initial oxide film was formed was subjected to hot water or high-temperature water or water vapor using test water having a working temperature of 280 to 340 ° C. and a dissolved oxygen amount of the real machine. High-temperature water treatment is performed in a two-phase environment for 24 to 240 hours.

Next, an in-steam treatment is performed in a high-pressure steam at 490 ° C. to 510 ° C. for 120 to 240 hours.

The corrosion susceptibility was evaluated by observing the appearance of the corrosion test specimen by the above treatment, inspecting for the presence of localized accelerated corrosion as shown in FIG. 5, and measuring the increase in corrosion and the thickness of the oxide film. I do.

The conditions of the multi-step initial oxidation treatment are as follows: the temperature is increased from room temperature to 250 ° C. in steps of 50 ° C., and the holding time of each step is 5 to 50 hours. The pressure of the atmosphere is a high-temperature water environment, and may be a two-layer environment of high-temperature water and steam. The heating means, test water environment and water quality may be the same as in the case of the single-step treatment.

Next, after the formation of the unstable initial oxide film, a high-temperature water treatment and then a steam treatment are performed under the same conditions as in the case of the single-step treatment, and local accelerated corrosion as shown in FIG. By measuring the presence or absence of corrosion, the increase in corrosion, and the thickness of the oxide film,
Evaluate corrosion susceptibility.

After the initial oxidation treatment and the high-temperature water treatment, the corrosion state can be determined by measuring the electric resistance (specific resistance) of the formed oxide film.

Next, the reasons for setting the respective ranges of the heating temperature, the treatment time, and the dissolved oxygen amount of the test water in the initial oxidation treatment will be described.

The reason for setting the temperature of the initial oxidation treatment to 50 ° C. to 150 ° C. is that if the temperature is lower than 50 ° C., an initial oxide film cannot be formed, and
If the temperature exceeds 50 ° C., a dense and stable oxide film is formed on the entire surface of the material, and the degree of corrosion inherent to the material cannot be brought out in the subsequent treatment in steam, and the material cannot be selected. If the processing time is less than 5 hours, an initial oxide film unique to the material is not formed, and the characteristics of the material cannot be brought out. The longer the processing time, the better, but if it exceeds 50 hours, it is not preferable because the cost increases as an evaluation test method for material selection.

The reason why the amount of dissolved oxygen is set to 2 to 100 ppb is that if the amount of dissolved oxygen is less than 2 ppb, the oxide film is insufficiently formed if the treatment time is short, and if it exceeds 100 ppb, a dense oxide film is formed on all surfaces of the material. The degree of corrosion inherent in the material cannot be derived in the subsequent treatment in steam, which is not preferable from the viewpoint of material selection.

The temperature of the multi-step initial oxidation treatment is set to 5
The reason why the temperature is set to 250 ° C. in the 0 ° C. step is that an initial oxide film cannot be formed at a temperature lower than 50 ° C. Although a predetermined effect can be obtained up to 150 ° C., there is an effect of suppressing the growth of an unstable oxide film at 200 ° C. to 250 ° C. However, it is suitable for low corrosion resistant materials having high corrosion sensitivity.

If the processing time is less than 5 hours, an initial oxide film unique to the material cannot be formed. On the other hand, although the characteristics can be brought out even for 50 hours or more, a long-time treatment at 200 ° C. or more increases the effect of suppressing the growth of the unstable oxide film, which is not preferable as a result.

The reason why the amount of dissolved oxygen is 2 to 100 ppb is the same as that in the single-step initial oxidation treatment.

The greatest advantage of the above-described multi-step initial oxidation treatment is that, roughly, the material can be selected by water quality influence evaluation in a single test.

The high-temperature water treatment following the initial oxidation treatment is to initiate corrosion at the operating temperature of the actual plant. The reason for setting the treatment time to 24 to 240 hours is that approximately 24 hours are required for stabilization of corrosion, and evaluation with less variation is possible by holding for a longer time.
Time processing is enough. In addition, although the water quality can be added without adding a reagent, the effect can be more clearly evaluated by adding the reagent.

The in-steam treatment is a treatment for accelerating corrosion of an unstable oxide film affected by water quality in the initial oxidation treatment. When the temperature is set to 490 to 510 ° C., if the temperature is lower than 490 ° C., the corrosion rate is low and local accelerated corrosion does not occur. On the other hand, 510 ° C
If it exceeds 300, nodular corrosion is likely to occur, and it becomes difficult to select materials for water quality impact assessment.

The zirconium-based metal used in the corrosion evaluation method of the present invention is Sn: 1-2% by weight, F:
e: 0.05 to 0.24%, Cr: 0.05 to 0.15%,
Ni: a zirconium-based alloy in which 0.03 to 0.10% and the balance substantially Zr are preferable. More preferably,
Sn: 1.2 to 1.7%, Fe: 0.07 to 0.20%, C
r: 0.05 to 0.15%, Ni: 0.03 to 0.10%, and the balance is a zirconium group which is substantially Zr. Next, the present invention will be described based on examples.

[0042]

[Example 1] Z made of Zircaloy-2
The effect of water quality was evaluated for two types (materials A and B) of the cladding tubes with the r liner having different material compositions.

The composition of material A is 1.43% Sn, 0.16%
Fe, 0.10% Cr, 0.05% Ni, and the balance Zr. The composition of material B is 1.29% Sn, 0.19% Fe,
0.10% Cr, 0.07% Ni, balance Zr.

As shown in the schematic diagram of FIG. 3, the structure of the test piece was processed and formed so that the inner diameter matched the outer diameter of the heater pin (10.85 mm) and the length was 20 mm. This test piece was set in the high-temperature water corrosion cell of FIG. 4, and the initial oxidation treatment by a single-step treatment using a preheater, the high-temperature water treatment (dissolved oxygen DO: 200 ppb), and Processing was performed.

In the evaluation method of the present invention, when the material A and the material B are compared, as shown in FIG. 6, the corrosion sensitivity of the material A is higher because the oxide film thickness of the material A is larger than the oxide film thickness of the material B. Easy to do,
It was found that the corrosion susceptibility of the effect of water quality at 80 ° C and 150 ° C was high. Therefore, the material B can be applied as the cladding pipe of the plant having the water quality fluctuation, and the material A is determined to be unacceptable.

Further, a comparative treatment method (dissolved oxygen DO: 40)
At 0 ppb), the dissolved oxygen DO was higher than the range of the evaluation method according to the present invention, the thicknesses of the oxide films of the materials A and B were almost the same, there was no significant difference, and the material could not be selected.

The results of material selection by the evaluation method according to the present invention show the same tendency in actual furnace test results, and it was confirmed that the results agreed well.

Example 2 FIG. 7 is a diagram showing the results of applying the evaluation method of the present invention to test water to which test pieces of materials A and B used in Example 1 were added with reagents.

As a treatment method, a multi-step initial oxidation treatment and a high-temperature water treatment (dissolved oxygen DO: 200 ppb) shown in FIG.
And steam treatment.

The initial oxidation treatment was performed without any reagent as test water, sodium chromate (Na ₂ CrO ₄ ), and sodium sulfate (Na ₂ SO ₄ ), and the dissolved oxygen DO was 80 ppb. In the evaluation method according to the present invention, accelerated corrosion was identified when the material A was added with any of the reagents.

FIG. 5 shows the appearance of the test piece after the corrosion test. In the case of material A, a gray localized accelerated corrosion 8 different from nodular corrosion occurred. The other areas showed uniform black corrosion. In the comparative evaluation method (DO: 400 ppb), no localized accelerated corrosion was observed, and the entire surface exhibited uniform black corrosion.

As shown in FIG. 7, the material A obtained by the evaluation method of the present invention is characterized by local accelerated corrosion. The thickness of the oxide film at the local accelerated corrosion portion is determined by adding no reagent, adding Na ₂ SO ₄ , Na ₂ CrO ₄
In the order. This embodiment is extremely effective as data of material design in consideration of the use environment or the service life of the product.

Incidentally, the high concentration dissolved oxygen (D
O: 400 ppb) under the condition, no localized accelerated corrosion occurs,
Therefore, it indicates that the material cannot be selected.

The conventional method of 500 ° C., 10.3
Local accelerated corrosion could not be detected in a corrosion test by steam treatment in steam for 216 hours in MPa steam, and the thickness of the oxide film was 5.5 μm for material A and 5.0 μm for material B, and there was no significant difference between the two. It turns out that selection is not possible.

[0055]

[Table 1]

Table 1 summarizes the characteristics of material selection between the evaluation method of the present invention and the conventional evaluation method. The greatest feature of the method of the present invention is that water quality impact assessment can be performed with high reliability. The conventional corrosion test in steam cannot evaluate the water quality, and the high temperature water immersion test requires a long time for the evaluation.

Example 3 By measuring the specific resistance (Ω · cm) of the sample subjected to the initial oxidation treatment and the high-temperature water treatment,
Material selection can be performed.

In a sample having a small specific resistance, electrons in the oxide film can easily move, whereby oxygen is easily supplied to the interface between the host and the substrate, and the corrosion is accelerated. In a sample having a large specific resistance, since the oxide film is dense, the movement of electrons is small, so that oxygen is hardly supplied to the interface between the host and the substrate, so that the corrosion is not accelerated.

FIG. 8 shows the results of measuring the specific resistances of the samples A and B used in Example 1 which were similarly subjected to only the initial oxidation treatment and the high-temperature water treatment. As can be seen from FIG. 8, the specific resistance of the material B was larger than that of the material A, and the same result as in the above example was obtained.

The specific resistance was measured by the AC impedance method at room temperature with a voltage of 10 to 200 mV and a frequency of 1 m.
Hz to 100 kHz.

[0061]

According to the corrosion evaluation method of the present invention, localized accelerated corrosion of a zirconium-based metal material can be predicted in advance. You can also evaluate the impact of water quality,
This is a powerful evaluation test method for selecting zirconium-based metal materials.

[Brief description of the drawings]

FIG. 1 shows the temperature of the single-step temperature increasing initial oxidation treatment of the present invention.
It is a figure showing time.

FIG. 2 shows the temperature of the multi-step heating initial oxidation treatment according to the present invention.
It is a figure showing time.

FIG. 3 is a schematic diagram showing a relationship between a test piece and a heater pin.

FIG. 4 is a schematic view of a corrosion cell for initial oxidation treatment.

FIG. 5 is a schematic view of a test piece appearance after a treatment in steam.

FIG. 6 is a graph showing a thickness of an oxide film of a test piece subjected to a single-step temperature raising initial oxidation treatment.

FIG. 7 is a graph showing a thickness of an oxide film of a test piece in a multi-step temperature raising initial oxidation treatment.

FIG. 8 is a graph showing the electrical resistivity of an oxide film of a test piece after an initial oxidation treatment and a high-temperature water treatment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Test piece, 2 ... Heater pin, 3 ... Corrosion cell, 4 ... High temperature water, 5 ... High temperature water and steam, 6 ... Heater power supply, 7 ... Ground on test piece surface, 8 ... Local accelerated corrosion part.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Teruyoshi Abe 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd.Hitachi Research Laboratory Co., Ltd. No. 2 F-term in Hitachi New Clear Engineering Co., Ltd. (Reference) 2G050 AA01 AA04 BA01 BA10 CA02 DA01 EA01 EA05 EA06 EB07 EC03 EC05 2G075 AA02 BA20 CA38 CA45 DA14 DA15 EA10 FA01 FA10 FA20 FC06 FC13 FC16 GA21 GA34

Claims (9)

[Claims] 1. A method comprising: a. Heat treatment of zirconium-based metal in test water with a dissolved oxygen content of 2 to 100 ppb in high-temperature water or high-temperature water and steam at a constant temperature for a predetermined time (single-step treatment), or test with a dissolved oxygen content of 2 to 100 ppb After an initial oxidation treatment in which high-temperature water using water or high-temperature water and steam is heated stepwise at a predetermined temperature for a predetermined time (multi-step processing), b. Using a test water having the same amount of dissolved oxygen as the dissolved oxygen of the actual machine, performing high-temperature water treatment by heating at the actual operating temperature for a predetermined time, measuring the thickness of the oxide film formed on the surface of the zirconium-based metal, and accelerating local acceleration A method for evaluating the corrosion of zirconium-based metals, characterized by evaluating the presence or absence of corrosion. 2. A method comprising: a. Heat treatment of zirconium-based metal in test water with a dissolved oxygen content of 2 to 100 ppb in high-temperature water or high-temperature water and steam at a constant temperature for a predetermined time (single-step treatment), or test with a dissolved oxygen content of 2 to 100 ppb After an initial oxidation treatment in which high-temperature water using water or high-temperature water and steam is heated stepwise at a predetermined temperature for a predetermined time (multi-step processing), b. High-temperature water treatment using a test water having the same amount of dissolved oxygen as the amount of dissolved oxygen of the actual machine and heating at the actual machine operating temperature for a predetermined time; c. Once cooled, 490-510 ° C, 120
A method for evaluating corrosion of a zirconium-based metal, characterized by measuring the thickness of an oxide film formed on the surface of the zirconium-based metal and evaluating the presence or absence of local accelerated corrosion. 3. The test water used for the initial oxidation treatment is sodium chromate or sodium sulfate of 10 to ⁶ to 1
3. The method for evaluating corrosion of a zirconium-based metal according to claim 1, which contains 0 to ⁴ mol / l. 4. The method according to claim 1, wherein the single-step processing includes a heating temperature of 80 to
4. The method for evaluating corrosion of zirconium-based metals according to claim 1, wherein the treatment is performed at 150 [deg.] C. for 5 to 50 hours. 5. The multi-step process is performed at 50 to 250 ° C.
The method for evaluating corrosion of zirconium-based metals according to claim 1, 2 or 3, wherein the temperature is raised stepwise in steps of 50 ° C until the holding time in each step is 5 to 50 hours. 6. The high-temperature water treatment is performed at 280 to 340 ° C. and 24 to 24 in high-temperature water or two phases of high-temperature water and steam.
The zirconium-based metal corrosion evaluation method according to claim 1, wherein the zirconium-based metal is held for 0 hours. 7. The method for evaluating corrosion of a zirconium-based metal according to claim 1, wherein electric resistance is measured instead of measuring the thickness of the oxide film. 8. By weight, Sn: 1-2%, Fe: 0.0
5 to 0.24%, Cr: 0.05 to 0.15%, Ni: 0.2%
In a zirconium-based alloy containing 0.3 to 0.10% and the balance being substantially Zr, the dissolved oxygen amount is 80 ppb.
After heating for 24 hours at 3.9 MPa and 3.9 MPa in high-temperature water, the dissolved oxygen amount was 200 ppb and 288 ° C. and 6.9 MPa in high-temperature water.
Heat for 16 hours and then dissolve at 200 ppb
A zirconium-based alloy having a thickness of an oxide film after heating in steam of 00 ° C. and 10.3 MPa for 120 hours of 5.5 μm or less. 9. By weight, Sn: 1-2%, Fe: 0.0
5 to 0.24%, Cr: 0.05 to 0.15%, Ni: 0.2%
In a zirconium-based alloy having a concentration of 0.3 to 0.10% and the balance being substantially Zr, a dissolved oxygen amount of 50 ppb is 50%.
C, 7 hours, 100 ° C for 14 hours, 150 ° C for 7 hours,
After heat treatment with high temperature water for 14 hours at 200 ° C. and 7 hours at 250 ° C., 288 at 200 ppb of dissolved oxygen.
At 6.9 MPa in high-temperature water for 216 hours, and then at 500 ° C. and 10.3 MPa at 200 ppb of dissolved oxygen.
The thickness of the oxide film after heating for 216 hours in the water vapor of a is 1
A zirconium-based alloy having a thickness of 0 μm or less.