JPH07188737A - Corrosion resistant treatment of corrosion resistant apparatus for nuclear fuel reprocessing plant - Google Patents

Abstract

PURPOSE:To provide a corrosion resistant treatment method by a laser beam which does not form carbon precipitated parts on a corrosion resistant apparatus consisting of stainless steel products contg. above a prescribed content ratio of carbon. CONSTITUTION:Segregation metal layer exposed parts 6 of the corrosion resistant apparatus 5 for a nuclear fuel reprocessing plant consisting of the stainless steel products are irradiated with the laser beam 2, by which the surface layers thereof are melted and recrystallized. The segregation metal layer exposed parts 6 are reirradiated with the laser beam 2', by which the molten surface layers and heat affected zones 9 near these layers are subjected to a soln. heat treatment of rapid cooling after heating up to a temp. above the solubility limit and below the m.p.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion-resistant treatment method for a corrosion-resistant equipment for a nuclear fuel reprocessing plant, and more particularly to a carbon-precipitated portion for a corrosion-resistant equipment made of stainless steel containing carbon in a predetermined content or more. The present invention relates to a method of performing corrosion resistance treatment with a laser beam without forming a metal, and a method of performing corrosion protection treatment to build up a stainless steel material having high quench hardening ability without causing cracks.

[0002]

2. Description of the Related Art In the process of reprocessing spent nuclear fuel, the spent nuclear fuel is dissolved in a nitric acid solution, and reusable uranium and plutonium are extracted and purified from the solution.
The nitric acid solution and the solution of the spent nuclear fuel have strong corrosiveness, and corrode the wall of the equipment that comes into contact with them.

As a result, in general, the corrosion-resistant equipment of a nuclear fuel reprocessing plant is used for low-carbon steel having good corrosion resistance,
It is formed of a steel material having stabilized carbon, a steel material having a high chromium (Cr) content, a stainless steel material, or the like. In particular, components of corrosion-resistant equipment made of austenitic stainless steel or martensitic stainless steel and formed by forging or rolling are widely used.

However, the above stainless steel sometimes undergoes a forging / rolling process to change its metallographic structure and segregate its contained components to form a segregated metal layer composed of its crystal grains and inclusions. The segregated metal layer is deposited in a predetermined direction depending on the processing direction to form a segregated metal layer exposed portion in a part of the corrosion resistant device. When the segregated metal layer exists parallel to the wall of the device, the metal surface is totally corroded on average,
It has good corrosion resistance. However, when the segregated metal layer exists at an angle with respect to the wall surface of the component, corrosion proceeds along the segregated metal layer, which is easily corroded, and part of the erosion depth rapidly increases due to point corrosion. Reaches the wall of the device (this is called tunnel corrosion).

This phenomenon becomes particularly noticeable when the segregated metal layer exists perpendicular to the wall surface of the device. FIG. 13 shows an example of the forging direction of the corrosion-resistant equipment and a portion where the segregated metal layer is exposed. Reference numeral 100 in the drawing denotes a component of the forged corrosion resistant device, and the segregated metal layer exposed portion is likely to be formed in the portion indicated by the reference numeral 101 in the forging direction shown.

On the other hand, conventionally, the exposed portion of the segregated metal layer of the above-mentioned corrosion-resistant equipment is irradiated with a laser beam to melt the metal surface layer and subjected to rapid heating and quenching to improve the corrosion resistance. It was being tried to let them do.

FIG. 14 shows a conventional corrosion-resistant treatment method for melting by laser beam irradiation. In FIG. 14, the laser beam 60 is focused to a predetermined beam diameter by a condenser lens 61, and is irradiated onto the surface of a base material 62 made of martensitic stainless steel. According to this conventional method, the segregation metal layer (in this case, the boundary between the ferrite structure and another structure) which is easily corroded by the rapid heating / quenching action of the laser beam 60 becomes a crystal structure of fine particles, which causes a tunnel. Can improve corrosion. It should be noted that reference numerals 63 and 64 in FIG. 14 respectively indicate a portion melted by the laser beam 60 and a heat-affected zone.

On the other hand, there has been proposed a method of overlaying an austenitic stainless steel having excellent corrosion resistance on the exposed portion of the segregated metal layer of a corrosion resistant device which is easily corroded.

FIG. 15 shows TIG welding (Tungsten Inert G).
as Welding). Figure 1
5, an arc 72 is generated between the TIG torch 70 and the portion of the surface of the base material 71 to be overlaid, and a metal rod 73 serving as a overlay material is inserted into this arc, whereby the metal rod 73 is Melt and build-up layer 74 on the surface of the base material 71
To form.

FIG. 16 shows a plasma powder overlay method (hereinafter referred to as PT
(Referred to as “A”). In FIG. 16, the build-up apparatus used for PTA has a torch 80, which has an electrode 81 and a water-cooled tip 8.
2 and a nozzle 83. Electrode 81 and tip 82,
The electrodes 81 and the base material 84 are respectively configured to be applied with a voltage by the pilot power source PS1 and the main power source PS2 so that the electrode 81 side becomes positive. At first,
The electrode 81 and the tip 82 are controlled by the pilot power source PS1.
An arc is generated between the two
A plasma arc is generated by a plasma gas such as r or helium He, and then a voltage is applied between the electrode 81 and the base material 84 by the main power source PS2, and the chip 82 stabilizes the plasma heat source. In this state, the powdered build-up material,
A carrier gas such as argon Ar, carbon dioxide CO2, and helium He is introduced into the plasma gas from between the tip 82 and the nozzle 83. These build-up materials are melted to form a build-up layer 85 on the surface of the base material 84 under the shielding gas.

[0011]

However, in the conventional method of melting the metal surface of the segregated metal layer exposed portion of the corrosion resistant device by the above laser beam, the carbon content is about 0.
For 05% or more of the base material, carbide precipitates were sometimes formed in the heat affected zone shown in FIG. This carbide precipitation portion is easily corroded, and there is a problem that the corrosion resistance of the equipment is lowered.

On the other hand, in the above-mentioned conventional TIG welding or PTA build-up method, when the corrosion-resistant equipment is made of a base material having a high quench hardening ability such as martensitic stainless steel, the heat-affected zone hardens and cracks. It happened.
As a method of preventing the occurrence of cracks, a base material of about 400
A method of preheating to ° C is conceivable, but preheating may cause the original high temperature strength of the substrate to be lost.

Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional corrosion-resistant treatment method of the corrosion-resistant equipment for a nuclear fuel reprocessing plant, and to provide a corrosion-resistant equipment made of a stainless steel material containing carbon in a predetermined content or more. An object of the present invention is to provide a corrosion-resistant treatment method using a laser beam that does not form a carbide precipitation portion, and a corrosion-resistant treatment method that builds up a stainless steel material having a high quench hardening ability without cracking.

[0014]

In order to achieve the above object, a first method for corrosion-resistant treatment of a corrosion-resistant equipment for a nuclear fuel reprocessing plant according to the present invention is a segregation metal for a corrosion-resistant equipment for a nuclear fuel reprocessing plant, which is made of a stainless steel material. The exposed layer is irradiated with a laser beam, the surface layer is melted and recrystallized, and then the exposed portion of the segregated metal layer is re-irradiated with a laser beam, and the thermal effect of the melted surface layer and its vicinity is affected. It is characterized in that the part is subjected to a solution treatment of heating to a temperature not lower than the solid solution limit but not higher than the melting point and then rapidly cooling.

A second method of anticorrosion treatment of a corrosion resistant equipment for a nuclear fuel reprocessing plant according to the present invention is to irradiate a laser beam to an exposed portion of a segregated metal layer of a corrosion resistant equipment for a nuclear fuel reprocessing plant made of a stainless steel material, and use the laser beam. Powder of a corrosion-resistant build-up material is supplied to the high temperature portion to form a build-up layer on the surface of the segregated metal layer exposed portion.

[0016]

With the above structure, the first anticorrosion treatment method for the corrosion resistant equipment for nuclear fuel reprocessing plant of the present application melts the surface portion of the segregated metal layer exposed portion of the corrosion resistant equipment by the laser beam, and recrystallizes rapidly, The surface portion of the segregated metal layer becomes fine crystal grains and inclusions, and the corrosion resistance is greatly improved. Furthermore, the laser beam is re-irradiated to the portion subjected to the melting treatment, and the melted surface layer and the heat-affected zone in the vicinity thereof are heated to a temperature not lower than the solid solution limit and not higher than the melting point and rapidly cooled, The carbide in the heat-affected zone is solid-solubilized, whereby the easily corroded portion of the heat-affected zone can be eliminated.

Further, the second method of anticorrosion treatment of anticorrosion equipment for nuclear fuel reprocessing plant of the present application is to irradiate a laser beam on the exposed portion of the segregated metal layer of the anticorrosion equipment to powder a build-up material excellent in anticorrosion on a high temperature portion. To supply. In this case, since the laser beam has a high energy density, according to this method, the heat input to the base material is small, and the limited portion of the surface layer of the base material and the build-up material are melted to form a meat excellent in corrosion resistance. Form a raised layer. That is, according to this anticorrosion treatment method, since the heat input to the base material is small, the occurrence of cracks can be reduced even for the base material having a high quench hardening ability.

[0018]

Embodiments of the present invention will now be described with reference to the drawings.

The first anticorrosion treatment method of the anticorrosion equipment for a nuclear fuel reprocessing plant is a method of melting and solutionizing the surface of the anticorrosion equipment with a laser beam. FIG. 1 shows an example of the melting step. There is. In FIG. 1, reference numeral 1
Shows a laser beam oscillator, and this oscillator 1
The laser beam 2 oscillated by the transmission mirror 3
Is then reflected by the condenser lens 4, condensed by the condenser lens 4, focused once, and then irradiated onto the substrate 5.

The base material 5 is forged in the direction P shown in the figure. In this case, the segregated metal layer 6 exists substantially parallel to the forging direction P, and the surface 7 of the base material 5 has segregated metal. It is an exposed layer. Here, the base material 5 of this embodiment is stainless steel SUS431, and its composition is as follows.

Component name C Cr Ni Others SUS431 0.2 (wt%) 16 (wt%) 2 (wt%) On the other hand, typical processing parameters of the laser beam 2 in this step are as follows.

Laser output: 6 to 10 (kW) Condenser lens focal length: 254, 381, 508 (mm) Beam diameter on work piece: φ4 to φ30 (mm) Processing speed: 0.2 to 10 (m / Min) Shielding gas: 5 to 100 (lit / min) (any one of N2, Ar, and He) By irradiating the surface 7 of the base material 5 with the laser beam 2 having the above specifications, the surface of the base material 5 is irradiated. The portion is heated to a temperature equal to or higher than the melting point and melts to form the surface-melted layer 8. In this embodiment, the surface melting layer 8 is set to about 0.
The depth is 5 mm or more.

As described above, the substrate 5 is formed by the laser beam 2.
The surface of the is melted and cooled further rapidly, the layered ferrite structure undergoes a process of melting and recrystallization, the particles are made fine, and at the same time, carbide (Cr carbide) is dispersed. FIG. 2 shows an example of the thermal cycle of this melting step.

The substrate 5 that has undergone the melting step is subjected to the next solution heat treatment step. FIG. 3 shows the solution heat treatment step. As shown in FIG. 3, the solution heat treatment step of the present embodiment is performed by the same apparatus configuration as that of the melting step. However, the laser beam 2'used in this solution treatment step is different from the laser beam 2 used in the melting step, and its processing parameters are as shown below.

Laser output: 4 to 15 (kW) Condenser lens focal length: 254, 381, 508 (mm) Beam diameter on work piece: φ2 to φ30 (mm) Processing speed: 0.4 to 20 (m) / Min) Shielding gas: 5 to 100 (lit / min) The solution beam 9 of the surface melting layer 8 of the substrate 5 and the heat-affected zone in the vicinity thereof is not less than the solid solution limit by the laser beam 2'of the above specifications. That is, it is heated to a temperature equal to or lower than the melting point, and subsequently, rapid cooling similar to quenching is performed by a self-cooling action in laser irradiation. By this rapid heating and quenching, the carbide in the solution-treated layer 9 is solid-solubilized, and the region where the carbide is precipitated in the heat affected zone disappears.

According to the corrosion-resistant treatment method of this embodiment, even for a corrosion-resistant equipment for a nuclear fuel reprocessing plant, which is made of a stainless steel material having a relatively high carbon content, precipitation of carbides made of fine crystal particles and easily corroded Arealess surface layers can be formed.

The corrosion-resistant equipment manufactured by the corrosion-resistant treatment method of this example and the corrosion-resistant equipment treated by the conventional corrosion-resistant treatment method were immersed in a 6N boiling nitric acid solution for 1000 hours and a corrosion test was carried out. Corrosion-resistant equipment by treatment has a maximum erosion depth of the surface layer of 150 μm to 200 μm.
On the other hand, the maximum erosion depth of the corrosion-resistant equipment subjected to the corrosion-resistant treatment according to this example was 20 μm to 30 μm. As described above, according to the corrosion-resistant treatment method of the present embodiment, tunnel corrosion of the forged material and the rolled material can be effectively prevented, and the durability life of the corrosion-resistant equipment can be significantly extended.

Various laser beam irradiation methods can be considered. 4 and 5 show an example of a laser beam irradiation method.

In the laser beam irradiation method shown in FIG. 4, the laser beam 11 emitted from the laser beam oscillator 10 is used.
Is reflected by the convex surface boundary 13 and the concave surface boundary 14 of the segment mirror 12 and transmitted by the transmission mirror 15 while being focused,
It is irradiated onto the base material 16 while being focused.

Further, in the laser beam irradiation method of FIG.
The segment mirror 17 formed of a concave boundary also serves as a transmission mirror, and the segment mirror 17 reflects the incident laser beam 18 and irradiates it on the substrate 19 while converging it.

According to the laser beam irradiation method shown in FIGS. 4 and 5, by adjusting the segment mirror 12 and the segment mirror 17, the shape and diameter of the laser beam can be obtained according to the purpose of processing. Therefore, it is possible to manufacture a corrosion resistant device having excellent corrosion resistance.

FIG. 6 shows an example of laser beam irradiation using a YAG laser. In FIG. 6, the laser beam is the fiber 2 contained in the elongated processing head 20.
1, is condensed by the first condensing lens 22 and the second condensing lens 23, is reflected by the reflection mirror 24, and is emitted to the outside from the emission window 25 provided on the peripheral wall of the processing head 20. It The processing head 20 is inserted from the opening of the component 26 of the corrosion-resistant device into the inside thereof,
Rotate in direction B while moving in direction A-A '. By irradiating the laser beam from the emission window 25 along with the above operation, the inner peripheral surface of the component 26 of the corrosion resistant device can be subjected to the corrosion resistant treatment.

In the anticorrosion treatment method of the above-mentioned embodiment, the surface layer of the anticorrosion equipment is melted by the laser beam, once crystallized and then re-irradiated with the laser beam, the solution treatment is carried out, but only the solution treatment is carried out. Can be performed by a heating furnace.

FIG. 7 shows that the solution treatment is being carried out in a heating furnace. In FIG. 7, reference numeral 27 indicates a corrosion-resistant device that has been subjected to a melting treatment by a laser beam. The corrosion-resistant device 27 is housed inside a heating furnace 28 and heated to a solution treatment temperature by a heater 29. Then, it is rapidly cooled by a coolant 31 such as water or oil injected from a coolant inlet 30 of the heating furnace 28. Coolant 3
1 may be an operating gas such as air or an inert gas.
According to this solution heat treatment method, the melted layer having a large area can be solution-treated at the same time, and the corrosion resistance treatment can be efficiently performed.

Next, the corrosion resistant treatment method for the corrosion resistant equipment for a nuclear fuel reprocessing plant according to the second aspect of the present invention will be explained.

The second method of anticorrosion treatment of anticorrosion equipment for nuclear fuel reprocessing plant of the present application is to form a built-up layer having excellent anticorrosion property on the surface of the segregated metal layer exposed portion of anticorrosion equipment.
Shows an example of the build-up process.

In the embodiment shown in FIG. 8, the base material 40 of the corrosion-resistant equipment component for padding is martensitic stainless steel S.
It consists of US 431 and its composition is shown below.

Component name C Cr Ni Others SUS431 0.2 (wt%) 16 (wt%) 2 (wt%) The above base material 40 has a processing table 4 whose one end is rotatable.
It is held at 1. A laser device 42 and a build-up material supply device 43 are arranged above the base material 40.

In the laser device 42, a laser beam 44 is emitted from an oscillator 45, passes through a transmission mirror 46, is further focused by a condenser lens 47, is once focused, and then is irradiated on the surface of the substrate 40. On the other hand, the build-up material supply device 43 has a container 49 accommodating a powdery build-up material 48, and the build-up material 48 passes through a tube 50 connected to the bottom of the container 49 and is heated by the laser beam 44 to a high temperature. Supplied to the department. This overlay material 48 is made of stainless SUS3.
It is composed of 04L and its composition is shown below.

Component name C Cr Ni Others SUS304L 0.05 (wt%) or less 9.0-11.0 (wt%) 17.0-22.0 (wt%) The processing conditions for the padding at this time are as follows.

Laser output: 6 to 10 (kW) Condenser lens focal length: 254, 381, 508 (mm) Beam diameter on work piece: φ5 to φ30 (mm) Processing speed: 100 to 5000 (m / min) ) Build-up material supply rate: 10 to 100 (g / min) The surface layer of the base material 40 is melted by irradiating the surface of the base material 40 with the laser beam 44 under the above conditions, and the supplied build-up material 48. Together with this, the overlay layer 51 is formed. According to this method, since the energy density of the laser beam 44 is high, only a very limited portion of the surface layer of the base material 40 is instantaneously melted, so that heat input to the base material 40 is small and quench hardening is performed. It is possible to perform overlay processing on a base material having high performance without causing cracks.

Further, according to the anticorrosion treatment method for forming the overlay layer, the overlay layer has a thickness of 1 mm to 3 mm per layer, and by stacking multiple layers, more excellent corrosion resistance can be obtained. You can

Of course, in the above-mentioned build-up processing, the base material 40
In order to reduce the curing of the base material, the substrate 40 is appropriately preheated (10
It is also possible to carry out 0 ° C to 200 ° C). Further, if the laser output is set to 10 kW, even faster processing can be realized.

FIG. 9 shows an example of another build-up process of supplying the build-up material to the front side in the moving direction of the irradiation portion of the laser beam. 9, the same parts as those in FIG. 8 are designated by the same reference numerals and the description thereof will be omitted. In this case, the overlay material 48 is
It is placed on the base material 40 in front of the moving direction of the irradiation portion of the laser beam 44 by the build-up material supply device 43 and melted together with the surface layer of the base material 40 by the moving laser beam 44 to form the build-up layer 51. To do. The operation of this processing example is exactly the same as in the case of FIG.

10 to 12 show an example of the overlay processing in which the irradiation diameter and shape of the laser beam can be adjusted.

In FIG. 10, the laser beam 44 becomes a light beam which is converged by the action of the segment mirror 54 composed of the convex boundary 52 and the concave boundary 53, is transmitted by the transmission mirror 55, and then is irradiated onto the substrate 40. . In this case, the overlay material is supplied to the laser beam irradiation section by the method described with reference to FIGS. 8 and 9. In FIG. 11, the laser beam 44
Is reflected by the segment mirror 56 having a concave boundary and is irradiated onto the base material 40 while being focused. The supply device for the overlay material is not shown. In FIG. 12, the transmission mirror 57 and the segment mirror 58 are combined to irradiate the laser beam 44 on the substrate 40 while converging it.

In any of the above laser beam irradiation methods, the diameter and shape of the laser beam irradiation portion can be adjusted by adjusting the segment mirrors 54, 56, 58, and processing can be performed according to the purpose. It can be carried out.

Next, a description will be given of an example in which the above-mentioned overlay processing is carried out as a part of the heat treatment step of the base material. In this example, after the annealing of the base material of the corrosion-resistant equipment, it is padded,
After the build-up layer is formed, the substrate is subjected to quenching and tempering. Here, in the annealing, the substrate is heated to 730 ° C. to 750 ° C., then rapidly cooled to 100 ° C. or lower, further heated to 630 ° C. to 670 ° C., and again rapidly cooled. Further, the quenching is performed by heating to 1000 ° C. to 1050 ° C. after overlaying, immersing in an oil tank and quenching. The tempering is performed by heating to a temperature of 630 ° C to 700 ° C after quenching and cooling by forced air cooling.

According to this embodiment, the strength of the base material can be restored and the corrosion resistance of the overlay layer can be maintained.

In addition to this, it is conceivable that the substrate is annealed, quenched and tempered, and then subjected to overlay processing. In this case as well, the strength of the substrate is restored and the overlay of the overlay layer is formed. Corrosion resistance can be maintained.

According to the anticorrosion treatment method of forming the overlay layer on the exposed portion of the segregation metal layer of the above corrosion resistant equipment, the surface of the segregation metal layer deposited perpendicularly to the metal surface is covered with the overlay layer having excellent corrosion resistance. The tunnel corrosion can be prevented and the durability of the corrosion resistant equipment can be greatly extended. The conventional corrosion-resistant equipment and the corrosion-resistant equipment treated according to this embodiment are 6N.
When it was immersed in the boiling nitric acid solution for 1000 hours and a corrosion test was carried out, the maximum corrosion depth of the surface layer of the conventional corrosion-resistant equipment was 150 μm to 200 μm, whereas the corrosion resistance of this embodiment was The maximum erosion depth of the surface layer of the device was 20 μm to 30 μm.

In the above embodiment, stainless steel SUS304L is used as the overlay material. However, the overlay material may be any material such as Inconel (Ni-Cr-Fe) as long as the overlay layer having excellent corrosion resistance can be formed. Alloys) can be used. The composition of Inconel (Ni-Cr-Fe alloy) that can be used as the overlay material is shown below.

Component name Ni Cr Fe C Other Inconel 70 (wt%) or more 14-23 (wt%) Remainder 0.1 (wt%) or less

[0054]

As is apparent from the above description, the first anticorrosion treatment method for the corrosion resistant equipment for a nuclear fuel reprocessing plant of the present application is to melt the surface portion of the segregated metal layer exposed portion of the corrosion resistant equipment with a laser beam. It rapidly recrystallizes, and further heats the melted surface layer and the heat-affected zone in the vicinity to a temperature above the solid solution limit but below the melting point and then rapidly cooled, so that the carbide formed in the heat-affected zone becomes a solid solution. Even a base material made of stainless steel having a relatively high carbon content can be subjected to the anticorrosion treatment by the laser beam.

Further, in the second method of anticorrosion treatment of the anticorrosion equipment for nuclear fuel reprocessing plant of the present application, the exposed portion of the segregated metal layer of the anticorrosion equipment is irradiated with a laser beam and the powder of the corrosion-resistant overlay material is supplied to the high temperature portion. Therefore, the surface layer of the corrosion resistant device is melted together with the cladding material to form a cladding layer having excellent corrosion resistance.
In addition, this corrosion-resistant treatment method uses a laser beam having a high energy density, so that the heat input to the base material is small, and therefore, even if the base material has a high quench hardening ability, cracking does not occur. A hardfacing layer can be formed.

[Brief description of drawings]

FIG. 1 is a diagram showing a melting step of a corrosion resistant treatment method for a corrosion resistant equipment for a first nuclear fuel reprocessing plant of the present application.

FIG. 2 is a graph showing a thermal cycle of a melting process.

FIG. 3 is a diagram showing a solution heat treatment step of the corrosion-resistant treatment method for the corrosion-resistant equipment for the first nuclear fuel reprocessing plant of the present application.

FIG. 4 is a diagram showing an example of a laser beam irradiation method of a corrosion resistant treatment method for a corrosion resistant equipment for a first nuclear fuel reprocessing plant of the present application.

FIG. 5 is a diagram showing another example of the laser beam irradiation method of the corrosion-resistant treatment method for the corrosion-resistant equipment for the first nuclear fuel reprocessing plant of the present application.

FIG. 6 is a view showing still another example of the laser beam irradiation method of the corrosion-resistant treatment method for the corrosion-resistant equipment for the first nuclear fuel reprocessing plant of the present application.

FIG. 7 is a diagram showing a solution treatment step using a heating furnace in the corrosion-resistant treatment method for the corrosion-resistant equipment for a nuclear fuel reprocessing plant according to the first aspect of the present application.

FIG. 8 is a diagram showing a build-up processing step by the corrosion-resistant treatment method of the corrosion-resistant equipment for the second nuclear fuel reprocessing plant of the present application.

FIG. 9 is a view showing another build-up processing step by the corrosion-resistant treatment method of the corrosion-resistant equipment for the second nuclear fuel reprocessing plant of the present application.

FIG. 10 is a diagram showing an example of a laser beam irradiation method of a corrosion resistant treatment method for a corrosion resistant equipment for a second nuclear fuel reprocessing plant of the present application.

FIG. 11 is a view showing another example of the laser beam irradiation method of the corrosion-resistant treatment method for the corrosion-resistant equipment for the second nuclear fuel reprocessing plant of the present application.

FIG. 12 is a view showing still another example of the laser beam irradiation method of the corrosion-resistant treatment method for the corrosion-resistant equipment for the second nuclear fuel reprocessing plant of the present application.

FIG. 13 is a diagram showing an example of a relationship between a forging direction of a corrosion resistant device for a nuclear fuel reprocessing plant and an exposed portion of a segregated metal layer.

FIG. 14 is a diagram showing one step of a conventional anticorrosion treatment method of melting a surface layer of an anticorrosion device with a laser beam.

FIG. 15 is a diagram showing one step of a conventional corrosion-resistant treatment method for forming a built-up layer on the surface of a corrosion-resistant device by a TIG welding method.

FIG. 16 is a diagram showing one step of a conventional anticorrosion treatment method of forming a built-up layer on the surface of an anticorrosion device by plasma.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 oscillator 2 laser beam 3 transmission mirror 4 condensing lens 5 base material 6 segregation metal layer 8 surface molten layer 9 solution layer 29 heater 40 base material 42 laser device 43 build-up material supply device 48 build-up material 51 build-up layer

Front page continuation (72) Inventor Ichiro Yoshimura 2-4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Keihin Office

Claims (5)

[Claims] 1. A laser beam is applied to the exposed portion of the segregated metal layer of a corrosion-resistant equipment for a nuclear fuel reprocessing plant made of stainless steel, the surface layer is melted and recrystallized, and then the exposed portion of the segregated metal layer is exposed. Re-irradiating with a laser beam, the melted surface layer and the heat-affected zone in the vicinity are subjected to solution treatment by heating to a temperature above the solid solution limit but below the melting point and quenching. Corrosion resistant treatment method for corrosion resistant equipment for processing plants. 2. A laser beam is applied to the exposed portion of the segregated metal layer of a corrosion-resistant equipment for a nuclear fuel reprocessing plant made of stainless steel, the surface layer is melted and recrystallized, and then the corrosion-resistant equipment is heated by a heater. The corrosion-resistant equipment for a nuclear fuel reprocessing plant, which is characterized by subjecting the melted surface layer and the heat-affected zone in the vicinity thereof to a solution treatment of heating to a temperature not lower than the solid solution limit and not higher than the melting point and quenching. Corrosion resistant treatment method. 3. A segregated metal layer of a corrosion-resistant equipment for a nuclear fuel reprocessing plant made of a stainless steel material is irradiated with a laser beam, and powder of a corrosion-resistant build-up material is supplied to a high temperature portion by the laser beam to produce the segregated metal. A corrosion-resistant treatment method for a corrosion-resistant equipment for a nuclear fuel reprocessing plant, characterized in that a build-up layer is formed on the surface of the exposed layer portion. 4. The corrosion resistant treatment for a corrosion resistant equipment for a nuclear fuel reprocessing plant according to claim 2, wherein the overlay material is made of either austenitic stainless steel or Inconel (Ni—Cr—Fe alloy). Method. 5. The build-up layer is formed after annealing the corrosion-resistant equipment, and the corrosion-resistant equipment is subjected to quenching and tempering treatment after the build-up layer is formed. The corrosion resistant treatment method for a corrosion resistant device for a nuclear fuel reprocessing plant according to claim 2 or claim 3.