JP2010071868A - Method of manufacturing spent nuclear fuel storage rack, filler material used for this method and the spent nuclear fuel storage rack manufactured by the method - Google Patents

Abstract

To improve weld joint performance of austenitic stainless steel containing boron.
In a method for manufacturing a spent nuclear fuel storage rack in which austenitic stainless steel containing boron is manufactured by welding, a filler material used for welding is C: 0.1 mass% or less, Si: 0.05. ˜0.65 mass%, Mn: 1.0 to 2.5 mass%, P: 0.03 mass% or less, S: 0.03 mass% or less, Ni: 9.0 to 12.0 mass% (or Ni: 12.0 to 15.0% by mass), Cr: 19.5 to 23.5% by mass (or Cr: 23.0 to 27.0% by mass), N: 0.1% by mass or less, It contains Mo: 1.0 mass% or less, Cu: 1.0 mass% or less, and the balance consists of inevitable impurities and Fe, and the amount of δ ferrite in the weld metal is 4.8-15 mass%.
[Selection] Figure 2

Description

  The present invention relates to a method for producing a spent nuclear fuel storage rack, a filler material used in the method, and a spent nuclear fuel storage rack produced by the method.

  A spent nuclear fuel storage rack (hereinafter, abbreviated as a fuel storage rack, as appropriate) is a spent nuclear fuel assembly until the spent nuclear fuel assembly used for power generation at a nuclear power plant is transported to a reprocessing plant. Is stored safely in the fuel storage pool.

  On the other hand, in order to make effective use of the limited fuel storage space, it is desired to increase the fuel storage capacity, and boron (boron), which is an element having a high neutron absorption capability, is required to increase the density or integration of the fuel storage rack. ) -Containing austenitic stainless steel (hereinafter abbreviated as boron-added stainless steel as appropriate) is used as a member that also serves as a neutron absorber and a structural strength member to form a fuel storage rack.

  For example, in the fuel storage rack described in Patent Document 1, a plurality of partition plates are assembled in a lattice shape, and a spent nuclear fuel assembly (hereinafter, referred to as a fuel assembly is appropriately referred to) in a cell that is the lattice-shaped space. I try to store it. In addition, the fuel storage rack described in Patent Document 2 or Patent Document 3 has a plurality of rectangular cylinders arranged in a checkered pattern to form a lattice-shaped cell that houses spent nuclear fuel assemblies. Since these fuel storage racks are made of boron-added stainless steel, they have an excellent shielding effect against neutrons, densify the fuel assemblies in the fuel storage racks, and improve the storage capacity. Can be done.

  In addition, since the fuel storage rack is required to have strength that satisfies earthquake resistance, a structure in which constituent members are firmly joined by welding is generally used. First, in the method for manufacturing a fuel storage rack described in Patent Document 1, first, a long partition plate is horizontally placed, a plurality of cut holes are formed in the long partition plate, and the short partition plate is formed in the cut holes. The formed convex part is inserted, a plurality of short partition plates are vertically attached, and each intersection point is fillet welded downward. Next, the other convex portion of the short partition plate is inserted into a notch hole of another long partition plate, and this portion is plug welded with a filler material (a filler rod or a filler wire), Fuel storage racks are manufactured by repeated plug welding. Similarly, in the method for manufacturing a fuel storage rack described in Patent Document 2 or 3, a plurality of rectangular cylinders are arranged in a checkered pattern, and between adjacent corners in the diagonal direction of two adjacent rectangular cylinders. A wedge-shaped joining member is provided, and a fuel storage rack is manufactured by repeating the operation of welding and joining both the joining member and the corner portion of the rectangular tube body with a filler material.

  By the way, austenitic stainless steel is used for a filler material or a joining member used for welding described in Patent Documents 1 to 3. Generally, in welding austenitic stainless steel, a filler material containing a δ ferrite structure is used. This means that a good weld metal can be obtained by making the austenite structure in the weld metal structure formed by welding into a state containing some δ ferrite structure, and high-temperature cracking during welding can be prevented. Because. In particular, when the amount of δ ferrite is high, effects such as deformation due to welding shrinkage and reduction of residual stress can be obtained.

  Therefore, it is also recommended to use a welding rod having a high amount of δ ferrite in the welding of boron-added stainless steel. However, since boron-added stainless steel is a difficult-to-weld material, Patent Document 4 proposes to employ a welding method and welding conditions that take into account the ferrite content of the welded part when manufacturing a fuel storage rack. Yes.

  That is, according to Patent Document 4, when welding austenitic stainless steel to which boron is added in an amount of 0.1 to 1.5 mass%, as a filler material during welding, C: 0.1 mass% or less, Si : 0.05 to 0.65% by mass, Mn: 1.0 to 2.5% by mass, Ni: 8.0 to 10.5% by mass, Cr: 28.0 to 32.0% by mass, Mo: 0 .5% by mass or less, P: 0.03% by mass or less, S: 0.03% by mass or less, and welding with a duplex stainless steel composed of the balance unavoidable impurities and Fe, and the ferrite content of the weld metal Is described as 15 to 40%. According to this, it is excellent in weldability, and it is possible to suppress warpage, distortion due to welding, distortion and residual stress as much as possible, prevent the occurrence of hot cracks that occur in the welded part, high quality and high reliability. It is said that a welded part can be obtained and the accuracy between storage cells can be maintained, so that a highly accurate spent fuel storage rack excellent in manufacturing workability can be manufactured.

Patent No. 3020675 Japanese Patent No. 2568317 Japanese Patent No. 3141491 Japanese Patent Laid-Open No. 2007-24609

  However, there is room for improvement in the welding method described in Patent Document 4.

  That is, boron (B) added to the boron-added stainless steel is a strong austenite generating element, and the weld metal containing B melted from the base material at the time of welding tends to preferentially have an austenite structure. For this reason, in the weld metal of boron-added stainless steel, the δ ferrite structure is reduced, and a complete austenite structure is easily formed. Therefore, in the welding assembly process of the fuel storage rack, the deformation due to generation of residual stress, distortion, etc. is increased, and the accuracy of the interval between the cells for storing the fuel assemblies and the assembly dimensions are likely to be lowered.

  In order to ensure the dimensional accuracy of the fuel storage rack and improve the quality, for example, in the case of the rack of the rectangular tube structure of Patent Documents 2 and 3, or the rack of the plate structure using the long partition plate and the short partition plate In order to prevent deformation of the rectangular tube body or the plate material, it is necessary to fix the dimensional accuracy at the time of welding assembling by fixing the rectangular cylinder body or the plate member to the assembly base with a restraining jig with a sufficient restraining force. However, the restraining force required to suppress deformation is large, and the restraining force is often set based on the experience of the operator, so that the assembly base and restraining jig are consumed quickly and it takes preparation for assembly. There is a problem that time increases and cost increases. In particular, since the fuel storage rack has a large number of welding points, the thermal deformation of the entire rack during welding is large, and deformation after welding is difficult to predict, so manufacturing time is prevented to prevent thermal deformation due to welding or to suppress weld cracking. There is a problem that becomes longer.

On the other hand, since B added to the boron-added stainless steel only dissolves about 100 ppm in the austenite structure, when the amount of B is large, iron (Fe) contained in the austenitic stainless steel during solidification of the weld metal, It reacts with chromium (Cr) or the like to form Fe, Cr boride (Fe, Cr) ₂ B. Since this boride has a lower melting point than the austenite structure, which is a metal, it has a feature of segregating at the grain boundaries of the weld metal, and is considered to be a cause of hot cracking during welding.

  Due to the difficult weldability of such boron-added stainless steel, welding workability is improved by improving the welding work management and inspection accuracy such as welding work conditions in order to prevent thermal deformation due to welding and to suppress weld cracking. To maintain product quality. For this reason, there is a problem in that the work burden and manufacturing man-hours of the welding worker are increased and the cost is increased.

  The problem to be solved by the present invention is to improve the welding workability of austenitic stainless steel containing boron (B) as a neutron absorber, to reduce the burden on the welding operator, and to improve the spent fuel storage rack It is to ensure quality.

  As a result of diligent research to solve the above problems, we have found the following solution principle.

  In order to suppress the high temperature cracking susceptibility of the welded portion of the boron-added stainless steel, which is the base material, when the boron addition amount of the boron-added stainless steel is, for example, about 1.0 mass%, the amount of δ ferrite of the weld metal is 40 mass. It is necessary to balance the strength of the welded joint portion while controlling the amount to be an appropriate amount within a range of% or less.

  Therefore, the present inventors have studied the compositional components of the filler metal. As will be described later, the maximum crack length is less affected by the amount of chromium (Cr), but the total number of cracks and the total crack length. Found that the amount of Cr greatly affected. That is, as in Patent Document 4, even if the amount of δ ferrite of the weld metal is controlled in the range of 15 to 40% by mass, if the amount of Cr increases (for example, 28.0 to 40.0% by mass), The number of cracks and total crack length increase rapidly.

  In view of these findings, the present invention provides a method for manufacturing a spent nuclear fuel storage rack in which austenitic stainless steel containing boron (B) as a neutron absorber is manufactured by welding. , C: 0.1% by mass or less, Si: 0.05 to 0.65% by mass, Mn: 1.0 to 2.5% by mass, P: 0.03% by mass or less, S: 0.03% by mass Hereafter, Ni: 9.0-12.0 mass%, Cr: 19.5-23.5 mass%, N: 0.1 mass% or less, Mo: 1.0 mass% or less, Cu: 1.0 mass %, The remainder is unavoidable, and welding is performed using a material composed of Fe.

  As a result, the amount of δ ferrite in the weld metal was 4.8 to 15% by mass, but a good result was obtained that the total crack length of the hot crack was only about 10% or less of the weld length. That is, it is possible to obtain a welded joint that can reduce hot cracking and can maintain the mechanical properties of the weld metal such as 0.2% proof stress, tensile strength, and elongation equal to or higher than the base metal, as will be described later. It was. As a result, the welding workability of the boron-added stainless steel can be improved, the burden on the welding operator can be reduced, and the high quality of the spent fuel storage rack can be ensured. In other words, it is possible to reduce the management of welding conditions at the time of production, inspection of welded parts, etc., and it is possible to reduce welding man-hours and welding difficulty. Obtainable.

  In this case, in the weld metal formed by welding, in addition to the composition of the filler material, welding may be performed under a welding condition in which 10 to 20% by mass of the boron contained in the austenitic stainless steel is melted. preferable.

  Further, in the present invention, instead of the composition of Ni and Cr in the above-described solution material, a solution material of Ni: 12.0 to 15.0 mass% and Cr: 23.0 to 27.0 mass% is used. it can. Even in this case, the amount of δ ferrite in the weld metal is 4.8 to 15% by mass, improving the workability of boron-added stainless steel, reducing the burden on the welder, and increasing the spent fuel storage rack Quality can be ensured.

  The production method of the present invention can be applied when welding austenitic stainless steel to which 0.1 to 2.0% by mass of boron is added, but has a high concentration to which 1.0 to 2.0% by mass of boron is added. It is preferable to apply to austenitic stainless steel to which boron is added.

  The composition of the weld metal of the welded portion of the fuel storage rack manufactured by the manufacturing method of the present invention is as follows: C: 0.1% by mass or less, Si: 0.05 to 0.65% by mass, Mn: 1.0 to 2 0.5% by mass, P: 0.03% by mass or less, S: 0.03% by mass or less, Ni: 9.0 to 12.0% by mass (or Ni: 12.0 to 15.0% by mass), Cr: 19.5 to 23.5 mass% (or Cr: 23.0 to 27.0 mass%), N: 0.1 mass% or less, Mo: 1.0 mass% or less, Cu: 1.0 It consists of a mass% or less, the balance of inevitable impurities and Fe, and the amount of δ ferrite in the weld metal is 4.8 to 15 mass%. According to this, the fuel storage rack excellent in the mechanical strength of the welded joint can be realized.

  The fuel storage rack of the present invention preferably contains 10 to 20% by mass of the boron contained in the austenitic stainless steel in the weld metal.

  According to the present invention, the weldability of austenitic stainless steel containing boron (B) as a neutron absorber is improved, the burden on the welding operator can be reduced, and the high quality of the spent fuel storage rack is ensured. be able to.

  Hereinafter, the manufacturing method of the spent nuclear fuel storage rack of this invention is demonstrated based on the Example and the Example of a filler metal.

  As shown in FIG. 1, the fuel storage rack 10 of the present embodiment accommodates a spent fuel assembly using austenitic stainless steel cell constituent member 20 to which boron (B) having a high neutron absorption capability is added. It is formed by integrating the cell constituent members 20 by welding so that a plurality of storage cells 30 having a rectangular cross section are arranged in a square lattice shape. In the present embodiment, the B addition amount is described as 1.0 to 2.0% by mass, but the present invention is not limited to this, and is also applicable to a base material having a B addition amount of 0.1 to 2.0% by mass. it can.

  Further, the weld metal of the fuel storage rack manufactured by welding according to the present embodiment is characterized in that the amount of δ ferrite is 4.8 to 15% by mass. That is, using a solution material containing a large amount of δ ferrite in advance, suppressing the decrease of δ ferrite structure in the weld metal that is completely ferrite structured by melting of B in the base metal, effective in suppressing hot cracking This ensures the amount of δ ferrite in the weld metal. In addition to this, in a weld metal containing a large amount of δ ferrite structure, welding shrinkage during cooling is alleviated, so that it is expected to reduce residual stress and welding deformation after welding.

  Here, it is known that hot cracking in the welding of austenitic stainless steel occurs when displacement exceeding the cracking limit occurs in the solidification brittle temperature region in the solidification process after welding. Therefore, the ballast strain test, which is used to evaluate the susceptibility to hot cracking, was carried out on boron-added stainless steel, and the amount of δ ferrite in the weld metal and the length of hot cracking that occurred in the weld metal obtained as a result of the ballast strain test. We investigated the relationship with the total and confirmed weld joint performance and workability.

  As a result, the composition of the weld metal was C: 0.1 mass% or less, Si: 0.05 to 0.65 mass%, Mn: 1.0 to 2.5 mass%, P: 0.03 mass% or less. S: 0.03 mass% or less, Ni: 12.0 to 15.0 mass%, Cr: 23.0 to 27.0 mass%, N: 0.1 mass% or less, Mo: 1.0 mass% Hereinafter, even if the amount of δ ferrite in the weld metal is reduced to 4.8 to 15% by mass, Cu: 1.0% by mass or less, the balance being unavoidable impurities and Fe, so-called high Cr and Ni. A good result was obtained that the total crack length of the hot crack was only about 10% or less of the weld length.

  In addition, it is preferable to use any of TIG welding, MIG welding, plasma welding, laser welding, and electron beam welding as a welding method applied to the manufacturing method of the fuel storage rack of the present invention.

  Hereinafter, the material composition of the welding solution used in the present embodiment will be described based on examples.

  In general, the weld metal of austenitic stainless steel desirably contains about several percent of δ ferrite in order to prevent weld cracking, and this is also true for boron-added stainless steel. In this example, the boron-added stainless steel having the chemical composition shown in the column of the base material in Table 1 was welded using the filler materials of Examples 1 and 2 and Comparative Examples 1 and 2, and their weld metals. A ballast rain test (hot cracking confirmation test) was conducted. As shown in Table 1, the boron-added stainless steel as a base material contains 1.07% by mass of B. In Table 1, Comparative Example 1 is a chemical composition of a general filler material used for austenitic stainless steel, Examples 1 and 2 are chemical compositions of a filler material used in the production method of the present invention, Comparative Example 2 is a chemical composition of a filler material having a higher Cr content than Examples 1 and 2.

Here, the chemical composition of the filler materials of Examples 1 and 2 shown in Table 1 will be described.
[C: 0.1% by mass or less]
C is an austenite stabilizing element, and contributes to strength improvement, so the content is preferably 0.1% by mass or less. More preferably, the content is preferably 0.03% by mass or less in order to suppress the C content of the boron-added stainless steel weld and the filler metal as much as possible and maintain the stress corrosion cracking resistance.
[Si: 0.05 to 0.65 mass%]
Si is used as a deoxidizer. The Si content of the welded portion of the boron-added stainless steel and the filler metal is desirably 0.05 to 0.65 mass%. That is, when the Si content is less than 0.05% by mass, the deoxidizing action of the welded portion is low, and when it exceeds 0.65% by mass, the corrosion resistance and toughness deteriorate.
[Mn: 1.0 to 2.5% by mass]
Mn has a deoxidizing action and a desulfurizing action at the time of welding, and has an effect of fixing S harmful to hot cracking and suppressing hot cracking resistance. In order to enhance this effect, 1.0% by mass or more is necessary. If the amount of Mn exceeds 2.5% by mass, the hot water flow at the time of welding deteriorates, causing a problem in workability.
[P: 0.03 mass% or less]
P is an element that generates a low-melting-point compound, and it is necessary to suppress it as much as possible. It is preferable that the P content of the filler material is 0.03% by mass or less.
[S: 0.03 mass% or less]
S is an element that generates a low-melting-point compound, and it is necessary to suppress it as much as possible. It is preferable that the S content of the filler metal is 0.03% by mass or less. More preferably, it is 0.005 mass% or less.
[Ni: 9.0 to 12.0 mass%, 12.0 to 15.0 mass%]
Ni is an essential component of the duplex stainless steel and stabilizes the austenite phase. For that purpose, it is necessary to make Ni content of a filler material into 9.0-15.0 mass%. When the Ni content of the filler material is less than 9.0% by mass, the ferrite phase in the welded portion increases and the toughness decreases. When the Ni content of the filler material exceeds 15.0% by mass, the austenite phase increases and hot cracking is likely to occur.

However, since Ni is a rare metal element, the Ni content of the filler metal is 9.0 to 12.0 mass% for the low Ni specification and 12.0 for the high Ni specification in consideration of the influence on cost. It is preferable to set it as -15.0 mass%.
[Cr: 19.5 to 23.5 mass%, 23.0 to 27.0 mass%]
Cr is an essential component of the duplex stainless steel and has the effect of stabilizing the ferrite phase. Further, it is an element that contributes to the improvement of the corrosion resistance of the duplex stainless steel alloy.

The Cr content of the filler material used for welding the boron-added stainless steel needs to be 19.5 to 27.0% by mass. When the Cr content is less than 19.5% by mass, Cr reacts with B to form borides such as Cr ₂ B, so that the effect of Cr stabilizing the ferrite phase is reduced and hot cracking is likely to occur. Become. On the other hand, if the Cr content exceeds 27.0% by mass, the ferrite phase is excessively increased, so that the ductility is lowered.

However, since Cr is a rare metal element, the Cr content of the filler metal is 19.5 to 23.5 mass% in the low Cr specification and 23.0 in the high Cr specification in consideration of the influence on the cost. It is preferable to set it to -27.0 mass%.
[N: 0.1% by mass or less]
N is a strong austenite-forming element and forms nitrides or carbonitrides with C, Cr, Ti, Mo, Nb, Ta, V, etc., and improves the strength by the precipitation effect. Since it becomes a cause of a defect, N content of a filler material has preferable 0.1 mass% or less.
[Mo: 1.0% by mass or less]
Mo, like Cr, is an element that contributes to the improvement of corrosion resistance. However, the Mo content of the filler material used for welding the boron-added stainless steel is preferably 1.0% by mass or less. If the filler metal contains a large amount of Mo, Mo reacts with B to form high melting point borides such as MoB ₂ , reducing the healing phenomenon that occurs in the weld zone and causing high temperature cracking. It becomes easy.
[Cu: 1.0% by mass or less]
Cu is solid-dissolved uniformly up to about 3.0% by mass in austenitic steel and strengthens the base, but slightly impairs toughness and becomes sensitive to hot cracking when added in large amounts, so the Cu content of the filler metal Is preferably 1.0% by mass or less.

  Here, returning to Table 1, the Ni content of the filler material of Example 1 is equivalent to that of Comparative Example 1, but is higher than that of Comparative Example 2. Further, the Ni content of the filler material of Example 2 is larger than those of Comparative Examples 1 and 2. That is, it can be seen that Examples 1 and 2 are generally high Cr and high Ni filler materials compared to Comparative Example 1.

比較例１、２及び実施例１、２に示した各溶加材を用いてボロン添加ステンレス鋼を溶接した溶接部について比較を行なった結果を表２に示す。

Table 2 shows the results of comparison of the welds obtained by welding the boron-added stainless steel using the filler materials shown in Comparative Examples 1 and 2 and Examples 1 and 2.

表２において、希釈率は、Ｂを含有しない溶加材により母材のボロン添加ステンレス鋼を溶接すると、溶接時の入熱により母材と溶加材の両方の成分が溶融混合し、溶接金属中のＢは母材のＢが希釈された状態になることを表している。この希釈率は、溶接継手部の形状、溶接開先、母材のＢ量と溶接金属量とのバランス等から定まる。これらを適切に設計することにより希釈率が決まる。本実施例の確認試験では、希釈率を１０％と２０％に設定して比較した。

In Table 2, the dilution ratio is as follows. When the base material containing boron-added stainless steel is welded with a filler material containing no B, both the base material and the filler material are melted and mixed by heat input during welding. B in the middle represents that the base material B is diluted. This dilution rate is determined by the shape of the weld joint, the weld groove, the balance between the B amount of the base metal and the weld metal amount, and the like. The dilution rate is determined by designing these appropriately. In the confirmation test of this example, the dilution rates were set to 10% and 20% for comparison.

  As a result of the comparison shown in Table 2, it was confirmed that in Examples 1 and 2 and Comparative Example 2, the amount of δ ferrite in the welded portion was higher than that in Comparative Example 1. In particular, in the case of the high Cr filler metal of Comparative Example 2, the amount of δ ferrite was as high as 28.2 to 34%.

  On the other hand, the results of the high-temperature cracking-sensitive ballast train test for Comparative Examples 1 and 2 and Examples 1 and 2 are shown in FIGS. In these figures, the horizontal axis indicates Comparative Example 1, Example 1, Example 2, and Comparative Example 2, and the vertical axis indicates the maximum crack length, the total crack length (mm), and the total number of cracks. Yes. FIG. 2 is an example of a dilution rate of 10%, and FIG. 3 is an example of a dilution rate of 20%.

  As shown in FIGS. 2 and 3, a good result was obtained in which the filler material of Example 2 had a total crack length of hot cracks of only 5 mm, which was about 10% or less of the weld length at the time of the test. Next, in the case of the dilution rate of 10% in Example 1, the total crack length is 6 mm, but a good result substantially equivalent to that in Example 2 is obtained, and the high Cr, high Ni filler material has few cracks. It has been found that a weld metal is obtained. However, in Comparative Example 2 in which the Cr content is too high, the amount of δ ferrite is the highest from the results in Table 2, but when considering the crack susceptibility test results of FIGS. It turns out that it becomes a result equivalent to a certain comparative example 1.

  Furthermore, the mechanical property of the welding part using each filler material is shown to FIG. In these figures, the horizontal axis indicates the base material, Comparative Example 1, Example 1, Example 2, and Comparative Example 2, and the vertical axis indicates 0.2% proof stress, tensile strength (MPa), and elongation (%). is there. FIG. 4 is an example of a dilution rate of 10%, and FIG. 5 is an example of a dilution rate of 20%.

  As can be seen from FIGS. 4 and 5, the 0.2% proof stress, tensile strength, and elongation are the same as those of Examples 2 and 3 in comparison with Comparative Example 1 that is a general filler material. The mechanical properties were 0.2% yield strength of 300 to 400 MPa, tensile strength of 600 to 700 MPa, and elongation of about 35%. When the evaluations of FIGS. 2 to 5 are comprehensively examined, it is understood that the weld metal using the filler metal of Examples 1 and 2 is optimal from the hot cracking and the strength characteristics of the welded portion.

  Here, the schematic block diagram of a fuel storage rack is shown in FIGS. The fuel storage rack of FIG. 6 is formed in a space in which a plurality of storage cells 31 are surrounded by a plurality of rectangular cylinders 21 or the rectangular cylinders 21, and a plate 22 is disposed between the outermost rectangular cylinders. The rectangular tube body 21 is arranged in a checkered pattern, and is appropriately welded with the filler material of Example 1 or 2 by appropriately providing bonding members (not shown) in the spaces of the corner portions adjacent to each other, and weld metal. 41 and 42 are joined.

  In the fuel storage rack of FIG. 7, a plurality of storage cells 32 are combined with a plurality of long partition plates 23 and a plurality of short partition plates 24 and are welded together using the filler material of Example 1 or 2. Formed. Here, the plurality of storage cells 32 are joined to each other at the intersection where the long partition plate 23 and the short partition plate 24 cross each other by the weld metal 43 by, for example, fillet welding. At this time, the welding at the intersection where the long partition plate 23 and the short partition plate 24 cross each other may be performed from both sides as shown in FIG. 7 if the groove shape or the like is appropriately designed. As shown in FIG. 4, the operation may be performed from only one side.

  As described above, by using the filler materials of Examples 1 and 2, by combining the B addition amount of boron-added stainless steel and the B dilution rate from the base material at the welded portion, Welded joint performance and workability can be improved. In addition, the optimum amount of δ ferrite and required strength of the weld metal can be easily achieved. As a result, the burden on the welding operator can be reduced, and a fuel storage rack having high quality and high reliability can be manufactured.

It is a conceptual block diagram of the fuel storage rack of one Embodiment with which the manufacturing method of this invention is applied. It is a graph which shows the sensitivity of the hot crack of the welding part in the case of the dilution rate of 10% using the filler material of the Example of this invention, and the filler material of a comparative example. It is a graph which shows the sensitivity of the hot crack of the welding part in the case of the dilution rate of 20% using the filler material of the Example of this invention, and the filler material of a comparative example. It is a graph which shows the mechanical property of the welding part in case the dilution rate is 10% using the filler material of the Example of this invention, and the filler material of a comparative example. It is a graph which shows the mechanical property of the welding part in the case of 20% of dilution rate using the filler material of the Example of this invention, and the filler material of a comparative example. It is a conceptual block diagram of the fuel storage rack of one Embodiment comprised using the square cylinder to which the manufacturing method of this invention is applied. It is a conceptual block diagram of the fuel storage rack of one Embodiment which uses the partition plate to which the manufacturing method of this invention is applied, and has a welding part in the both sides of an intersection part. It is a conceptual block diagram of the fuel storage rack of one Embodiment using the partition plate with which the manufacturing method of this invention is applied, and a welding part is only one side of an intersection part.

Claims (10)

In the method of manufacturing a spent nuclear fuel storage rack for manufacturing by welding austenitic stainless steel containing boron,
The filler material used for the welding is C: 0.1 mass% or less, Si: 0.05 to 0.65 mass%, Mn: 1.0 to 2.5 mass%, P: 0.03 mass% or less. , S: 0.03% by mass or less, Ni: 9.0-12.0% by mass, Cr: 19.5-23.5% by mass, N: 0.1% by mass or less, Mo: 1.0% by mass Hereafter, the manufacturing method of the spent nuclear fuel storage rack characterized by containing Cu: 1.0 mass% or less and consisting of remainder unavoidable impurities and Fe. In the method of manufacturing a spent nuclear fuel storage rack for manufacturing by welding austenitic stainless steel containing boron,
The filler material used for the welding is C: 0.1 mass% or less, Si: 0.05 to 0.65 mass%, Mn: 1.0 to 2.5 mass%, P: 0.03 mass% or less. , S: 0.03% by mass or less, Ni: 12.0-15.0% by mass, Cr: 23.0-27.0% by mass, N: 0.1% by mass or less, Mo: 1.0% by mass Hereafter, the manufacturing method of the spent nuclear fuel storage rack characterized by containing Cu: 1.0 mass% or less and consisting of remainder unavoidable impurities and Fe. In the manufacturing method of the spent nuclear fuel storage rack of Claim 1 or 2,
In the weld metal formed by welding, in addition to the composition of the filler material, welding is performed under a welding condition in which 10 to 20% by mass of the boron contained in the austenitic stainless steel is melt-mixed. Manufacturing method of spent nuclear fuel storage rack. In the manufacturing method of the spent nuclear fuel storage rack of Claim 1 or 2,
A method for producing a spent nuclear fuel storage rack, wherein the boron is contained in the austenitic stainless steel in an amount of 1.0 to 2.0% by mass.   It is a filler material used for welding austenitic stainless steel containing boron, and C: 0.1% by mass or less, Si: 0.05 to 0.65% by mass, Mn: 1.0 to 2.5% by mass %, P: 0.03 mass% or less, S: 0.03 mass% or less, Ni: 9.0 to 12.0 mass%, Cr: 19.5 to 23.5 mass%, N: 0.1 mass %, Mo: 1.0 mass% or less, Cu: 1.0 mass% or less, and the filler material which consists of remainder unavoidable impurities and Fe.   It is a filler material used for welding austenitic stainless steel containing boron, and C: 0.1% by mass or less, Si: 0.05 to 0.65% by mass, Mn: 1.0 to 2.5% by mass %, P: 0.03 mass% or less, S: 0.03 mass% or less, Ni: 12.0 to 15.0 mass%, Cr: 23.0 to 27.0 mass%, N: 0.1 mass %, Mo: 1.0 mass% or less, Cu: 1.0 mass% or less, and the filler material which consists of remainder unavoidable impurities and Fe. In spent nuclear fuel storage racks manufactured by welding austenitic stainless steel containing boron,
The weld metal formed by welding is C: 0.1 mass% or less, Si: 0.05 to 0.65 mass%, Mn: 1.0 to 2.5 mass%, P: 0.03 mass% or less. , S: 0.03% by mass or less, Ni: 9.0-12.0% by mass, Cr: 19.5-23.5% by mass, N: 0.1% by mass or less, Mo: 1.0% by mass Hereinafter, a spent nuclear fuel storage rack comprising Cu: 1.0 mass% or less, the balance of inevitable impurities and Fe, and the amount of δ ferrite in the weld metal being 4.8 to 15 mass%. In spent nuclear fuel storage racks manufactured by welding austenitic stainless steel containing boron,
The weld metal formed by welding is C: 0.1 mass% or less, Si: 0.05 to 0.65 mass%, Mn: 1.0 to 2.5 mass%, P: 0.03 mass% or less. S: 0.03 mass% or less, Ni: 12.0 to 15.0 mass%, Cr: 23.0 to 27.0 mass%, N: 0.1 mass% or less, Mo: 1.0 mass% Hereinafter, a spent nuclear fuel storage rack comprising Cu: 1.0% by mass or less and the balance of inevitable impurities and Fe, wherein the amount of δ ferrite in the weld metal is 4.8-15% by mass. The spent nuclear fuel storage rack according to claim 7 or 8,
The spent nuclear fuel storage rack, wherein the weld metal contains 10 to 20% by mass of the boron contained in the austenitic stainless steel. The spent nuclear fuel storage rack according to claim 7 or 8,
A spent nuclear fuel storage rack, wherein the boron is contained in the austenitic stainless steel in an amount of 1.0 to 2.0% by mass.

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