JP4335520B2 - Sealing structure of furnace bottom penetration part and sealing method of furnace bottom penetration part - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a structure for sealing a bottom through-hole and a method for sealing a bottom through-hole, and in particular, leakage of water at a penetration portion through which a penetration body such as an instrumentation cylinder of an existing nuclear reactor penetrates the bottom. The present invention relates to a sealing structure of a furnace bottom through portion and a method of sealing the furnace bottom through portion.
[0002]
[Prior art]
A penetration body such as an in-core instrument tube for mounting a neutron detection sensor or a drive mechanism for driving an in-reactor control target object passes through the bottom of the reactor vessel. The leakage of water at the penetration portion between the furnace bottom and the penetrating body is required to maintain the function of the penetrating body until repair work such as replacement work is performed. The repair work is further required to be completed in a short period of time because the plant stoppage period can be shortened. Establishment of a technology that realizes a sealing structure that makes such repair work unnecessary is required.
[0003]
[Problems to be solved by the invention]
The subject of this invention is providing the sealing structure of the furnace bottom penetration part which can prevent a leak reliably, and the sealing method of a furnace bottom penetration part.
Another object of the present invention is to provide a sealing structure for a furnace bottom penetrating part and a sealing method for the furnace bottom penetrating part that can shorten the plant shutdown period.
[0004]
[Means for Solving the Problems]
Means for solving the problem is expressed as follows. Technical matters appearing in the expression are appended with numbers, symbols, etc. in parentheses. The numbers, symbols, and the like are technical matters constituting at least one embodiment or a plurality of embodiments of the present invention or a plurality of embodiments, in particular, the embodiments or examples. This corresponds to the reference numbers, reference symbols, and the like attached to the technical matters expressed in the drawings corresponding to. Such reference numbers and reference symbols clarify the correspondence and bridging between the technical matters described in the claims and the technical matters of the embodiments or examples. Such correspondence or bridging does not mean that the technical matters described in the claims are interpreted as being limited to the technical matters of the embodiments or examples.
[0005]
The sealed structure of the bottom penetration portion according to the present invention includes a penetration body (3) that penetrates the bottom (2) of the nuclear reactor, and a joint portion where the penetration body (3) and the bottom (2) are joined. It is comprised from the coating body coat | covered from. The cladding that is joined to the bottom of the furnace but is physically non-integrated with the bottom of the furnace exists independently of the physical change of the joining site, and it is possible to further prevent leaks that are virtually impossible but virtually impossible. Can be prevented. The non-integration of the covering body is specifically realized by the presence of a closed space between the penetrating body (3) and the furnace bottom. The space effectively invalidates the physical bonding between the covering and the penetrating body, and can effectively prevent the physical change of the bonding portion from reaching the covering that is the cap.
[0006]
The covering body has a first annular weld layer (11) that directly covers the joining portion and the lower surface of the furnace bottom (2), and a first weld layer (11) that passes through the first weld layer (11) downward. A cap (1) surrounding the exposed portion (4) of the penetrating body (3) exposed below the weld layer (11), and a second weld layer (12) joined to the lower surface of the first weld layer (11). The outer peripheral surface of the upper end portion of the cap (1) and the third weld layer (14) joined to the second weld layer (12), the outer peripheral surface of the lower end portion of the exposed portion (4) and the cap (1) And a seal ring (15) mounted in an annular space between the inner peripheral surface of the lower end portion.
[0007]
In such a joining structure, the upper end portion of the cap (1) is joined to the first welding layer (11) via the second welding layer (12), and thus the cap (1) is joined to the second welding layer (12). And a first welded layer (11) and a novel joining structure for joining to the lower surface of the furnace bottom 2. A seal ring (15) is mounted between the lower end portion of the penetrating body (3) and the lower end portion of the cap (1), and a gap (18) between the cap (1) and the penetrating body (3) is provided. Maintained sealed. Even in the event that there is a risk of leakage at the penetrating site, the cap (1) can effectively avoid leakage at the site where there is such a risk.
[0008]
By using the first weld layer (11) attached at the time of manufacture, no local PWHT is required and the operation is easy.
[0009]
If the material of the first weld layer (11) is 600 alloy, it is important that the material of the second weld layer (12) is 690 alloy that is stronger against stress corrosion cracking than the 600 alloy. The joint site between the cap (1) and the second weld layer (12) is more strongly structured against stress corrosion cracking.
[0010]
An annular first on the outer peripheral surface of the upper end portion of the cap (1) 4 Weld layer ( 13 ) Become joints of 690 alloys and strengthens the structure. The second weld layer (12) is preferably joined to the annular upper end surface of the third weld layer (14). In this case, if the first weld layer (11) is an existing weld layer, the material of the first weld layer (11) is 600 alloy, and the material of the second weld layer (12) is 690 alloy, The material of the third weld layer (14) is 690 alloy. The joining of the second weld layer (12) and the third weld layer (14) is strong against stress corrosion cracking.
[0011]
The outer peripheral surface of the lower part of the penetrating body (3) and the lower end surface of the seal ring (15) are joined by the fifth weld layer (26), and the outer peripheral surface of the seal ring (15) and the cap (1) The lower end surface is joined by the sixth weld layer (27), and the sealing effect is enhanced. The lower part of the penetration body (3) is configured as a safe end. In this case, the seal ring (15) is sheathed and welded to its safe end.
[0012]
The addition of a gas supply pipe (16) that couples to the cap (1) is preferred. The inside of the gas supply pipe (16) is in contact with the annular space between the penetrating body (3) and the cap (1). It is effective that an on-off valve (29) is interposed in the gas supply pipe (16). An inert gas (eg, Ar gas) is supplied to the annular space (18) via the gas supply pipe (16). The inert gas is used as an atmosphere in the above-described welding process.
[0013]
The method for sealing a bottom bottom penetration according to the present invention is a method for sealing a bottom bottom penetration that prevents leakage between a penetration body (3) that penetrates the bottom (2) of the nuclear reactor and the bottom (2). A manufacturing step of manufacturing a pair of a first half-cracked cap (19) and a second half-cracked cap (12) at a factory, a first half-cracked cap (19) and a second half-cracked cap (21), A step of wrapping the penetrating body (3) in the field, and a forming step of joining the first half-cracked cap (19) and the second half-cracked cap (21) by welding to form one cap (1) And a joining step of joining the lid cap (1) to the furnace bottom (2) by welding, and a seal ring (18) in the annular space (18) between the lower end portion of the cap (1) and the penetrating body (3). 15) By fitting the penetrating body (3) and the cap (1) It is composed of the annular space (18) and a sealing step of sealing the.
[0014]
By joining the half-cracked cap and capping the existing penetrating body structure with the cap (1), it is possible to seal or repair it in a short construction period. By fitting the seal ring (15) into the annular space (18) between the lower end portion of the cap (1) and the penetrating body (3), the annular space between the penetrating body (3) and the cap (1) ( The construction for sealing 18) can be completed promptly.
[0015]
A first weld layer (11) that joins the penetrating body (3) and the lower surface of the furnace bottom (2) already exists in the furnace bottom (2). In the joining step, the first weld layer (11) is welded to the upper end portion of the cap (1) through the second weld layer (12). The through hole (3) and the first weld layer (11) already exist in the furnace bottom (2), and the second weld surrounds the through hole (3) in an annular shape on the lower surface of the first weld layer (11). A new joining step for joining the layer (12) is further added. The joining step is a step of welding the second weld layer (12) and the upper end portion of the cap (1). The new bonding step precedes the manufacturing steps described above in time. The manufacturing step includes a step of measuring an inner diameter dimension and a shape of the second weld layer (12), and a first small diameter portion by turning a constant thickness portion around the first cylinder and the second cylinder respectively. Forming the first first semi-finished product and the first second semi-finished product by forming the first small-diameter portion and the second small-diameter portion, respectively, and joining the first semi-circular weld layer (37) to the semi-circular region of the first small-diameter portion. Forming a second first semi-finished product (34), joining a second semi-circular weld layer (38) to a semi-circular region of the second small diameter portion to form a second second semi-finished product (35); 2 A center hole is formed in each of the first semi-finished product (34) and the second second semi-finished product (35), and the third first semi-finished product (34 ') and the third second semi-finished product (35') Forming a first half product (34 ') and a third second product (35'), and inner diameter dimensions (W1, W2). ) To form a first half-cracked cap (19) and a second half-cracked cap (21), respectively. The joining step is a step of welding the second weld layer (12) and the upper end portion of the cap (1) through the first half-circumferential weld layer (37) and the second half-circumferential weld layer (38), respectively. .
[0016]
Since the intermediate product of the half-cracked cap is manufactured at the factory, the short-term sealing or the repair thereof is further promoted.
[0017]
The step of coupling a gas inlet pipe (16) for introducing an inert gas into the annular space (18) to the cap (1) is added. The aforementioned new joining step has the step of introducing an inert gas into the annular space (18). The first weld layer (11) is formed of a 600 alloy, and the second weld layer (12), the first half-circumferential weld layer (37), and the second half-circumferential weld layer (38) are formed of a 690 alloy. .
[0018]
The sealing step includes a step of fitting the seal ring (15) into the annular space (18) like a wedge. Joining the lower surface of the seal ring (15) and the outer peripheral surface of the penetrating body (3) by welding, and joining the outer peripheral surface of the seal ring (15) and the lower surface of the cap (1) by welding; Is added more effectively.
[0019]
The bottom surface of the furnace bottom (2) is an inclined surface inclined with respect to the core axis, and the end faces of the first half-circumferential weld layer (37) and the second half-circumferential weld layer (38) are formed as elliptical ring surfaces. Is done. Such shaping is performed at the factory, which further contributes to short-term repair or short-term sealing.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Corresponding to the figure, in the embodiment of the sealed structure of the bottom penetration portion according to the present invention, an instrument tube that penetrates the reactor vessel bottom (hereinafter referred to as the reactor bottom) is arranged together with a cap. As shown in FIG. 1, the cap 1 covers a furnace bottom lower surface side portion 4 of the instrument tube 3 penetrating the furnace bottom 2 in the vertical direction on the furnace bottom lower surface side. The in-furnace instrumentation thimble (not shown) is arranged in the furnace from the inside of the instrumentation cylinder 3. In the annular periphery of the furnace bottom 2, the mirror surface 5 is formed obliquely in a conical shape. The illustrated instrument tube 3 penetrates the slope forming portion of such a furnace bottom. The reactor bottom 2 is said to be a reactor vessel lower mirror.
[0021]
The instrument tube 3 is fixed to the furnace bottom 2 with a welding alloy 6 on the upper surface side of the furnace bottom and is supported in the vertical direction. The cap 1 is a leakage protection cylinder added by repair. A furnace bottom lower surface side portion 4 which is a lower portion of the instrument tube 3 is surrounded by the cap 1. A safe end 7 is integrally connected to the bottom surface 4 of the bottom surface of the bottom surface 4 of the bottom of the furnace bottom and extends downward. A conduit tube 8 is tightly inserted into the safe end 7 in the vertical upward direction from the lower side thereof. It is difficult and practically impossible to pass the cap 1 from the end of the long conduit tube 8 not shown. The cap 1 is divided into two parts before the cap 1 is mounted, and is assembled into one cylinder at a position shown by welding.
[0022]
A welded and fixed multilayer structure 9 is interposed between the cap 1 and the furnace bottom 2. The weld-fixed multilayer structure 9 includes a first metal-made first weld layer 11, a second metal-made second weld layer 12, a second metal-made third weld layer 13, which are joined to the bottom surface of the furnace bottom 2. Formed and structured from a second metal fourth weld layer 14. The first metal-made first weld layer 11 is provided at the time of initial manufacture of the reactor vessel, and already exists at the start of repair work.
[0023]
As the first metal used for the first metal-made first weld layer 11, 600 alloy (a name definitely representing a metal material in the industry) is used. The second metal used in the second metal second weld layer 12, the second metal third weld layer 13, and the second metal fourth weld layer 14 is the same as the 690 alloy (in this industry). This is a definite name indicating a metal material in comparison with 600 alloy). These welding processes are performed in an atmosphere of 100% inert gas. The inert gas 100% atmosphere is formed by the inert gas introduced from the gas introduction tube 16 surrounding the welded portion.
reference:
690 Alloy: ASME Sec.IX Code Case2142 UNS NO6052FM
[0024]
As shown in FIG. 2, the second metal-made second weld layer 12 is welded to the annular lower surface of the first metal-made first weld layer 11, and the second metal-made second weld layer 12 is welded. 4 The weld layer 13 is welded to the cylindrical outer peripheral surface of the upper portion of the cap 1 and is welded to the second metal. 3 The weld layer 14 includes an annular lower surface of the second metal second weld layer 12 and the second metal second weld layer 12. 4 The welded layer 13 is welded to the outer peripheral surface of the cylindrical surface. Second metal made 3 The weld layer 14 is a fillet weld site.
[0025]
As shown in FIG. 1, a seal ring 15 is interposed between the inner cylindrical surface of the lower portion of the cap 1 and the outer cylindrical surface of the upper portion of the safe end 7. A gas introduction cylinder 16 is joined to the cap 1 at a lower portion of the cap 1. The gas introduction passage 17 of the gas introduction cylinder 16 is electrically connected to a closed annular space 18 surrounded by the furnace bottom lower surface portion 4, the seal ring 15, the weld-fixed multilayer structure 9, and the cap 1. As shown in FIG. 3, the annular space 18 is formed between the cylindrical outer peripheral surface of the furnace bottom lower surface side portion 4 and the cylindrical inner peripheral surface of the cap 1.
[0026]
As shown in FIG. 3, the cap 1 is structured into two parts, and is formed of a first half-crack cap 19, a second half-crack cap 21, and two butt weld sites 22. An in-furnace instrumentation thimble (not shown) is guided into the center hole 23 of the instrumentation cylinder 3.
[0027]
FIG. 4 shows a welded portion 22 where the first half-cracked cap 19 and the second half-cracked cap 21 are welded and joined at the butted portion facing each other on one circumference. The first half-cracked cap 19 and the second half-cracked cap 21 each have a width defined in the region from the upper end surface toward the lower side and the thickness defined in the thickness direction from the outer side toward the inner side. Each of them is shaved off from the base material. Second metal made as described above 4 The weld layer 13 occupies a ring-shaped space corresponding to the thickness that has been cut away.
[0028]
Second metal made 4 A welded portion 22 is welded to the butted portion of the first half-cracked cap 19 and the second half-cracked cap 21 in which the weld layer 13 is formed. The butt welding part 22 is formed of an upper longitudinal welding part (upper axial welding part) 24 located on the upper side and a lower longitudinal welding part (lower axial welding part) 25 located on the lower side. . The material of the upper longitudinal welded portion 24 is a second metal second 4 It is the same material (690 alloy) as the material of the weld layer 13. The material of the lower longitudinal welded portion 25 is a material (SUS316L) that is compatible with the material of the cap 1 (SUS316).
[0029]
FIG. 5 shows a welded structure in which the seal ring 15 is fixed to the safe end 7 and the lower end portion of the cap 1. The seal ring 15 is driven in a wedge shape from the lower side to the upper side between the safe end 7 and the cap 1. The seal ring 15 is more firmly fixed to the safe end 7 by a first seal welding portion 26 straddling the outer peripheral surface of the safe end 7 and the lower surface of the seal ring 15.
[0030]
The first seal welding portion 26 prevents gas leakage between the seal ring 15 and the safe end 7. The seal ring 15 is fixed to the cap 1 by a second seal welding portion 27 straddling the lower surface of the cap 1 and the outer peripheral surface of the seal ring 15. The second seal welding portion 27 prevents leakage between the seal ring 15 and the cap 1. Prior to such welding, the seal ring 15 has a split structure and is integrally formed by a longitudinal welded portion 28, as shown in FIG.
[0031]
As shown in FIG. 1, a sealing on-off valve 29 is interposed in the middle of the gas introduction passage 17. An inert gas is passed through the gas introduction passage 17 via the sealing on-off valve 29, and the air in the annular space 18 is replaced with the inert gas. The inert gas in the annular space 18 is sealed in a non-leakage state by a sealing on-off valve 29 that is closed. The inert gas forms a welding environment when forming the welded fixed multilayer structure 9. In Used.
[0032]
7 to 26 show an embodiment of a method for sealing a furnace bottom penetration according to the present invention. FIG. 7 shows the connection between the existing instrument tube 3 and the furnace bottom 2 before repair. As described above, the first metal-made first weld layer (600 alloy overlay) 11 is already fixed to the furnace bottom 2. FIG. 8 shows a sealing material insertion step for filling a gap between the furnace bottom 2 and the instrument tube 3. When leakage is found in the gap between the furnace bottom 2 and the instrumentation cylinder 3, the sealing material 31 is inserted into the gap.
[0033]
FIG. 9 shows a welding process in which the second metal second weld layer 12 is formed on the lower surface of the first metal first weld layer 11. The second metal-made second weld layer 12 is formed as a 690 alloy build-up seat that uses 690 alloy to join to the lower surface of the first metal-made first weld layer 11. The welding method is TIG welding. The welding posture is upward. The shielding gas used in the welding process is 100% inert gas. After the welding, a soundness confirmation inspection such as a defect existence inspection is performed by dimensional inspection of the second metal-made second weld layer 12 and ultrasonic or other flaw detection methods.
[0034]
FIG. 10 shows a countermeasure process for the tensile residual stress of the weld pile of the first metal first weld layer 11. Residual stress countermeasures are taken for the first metal first weld layer 11, and buffing by a buff 32 is exemplified as a treatment method for the countermeasures, and the first metal first weld layer 11 that is a 690 alloy build-up is tensile. Residual stress is removed.
[0035]
FIG. 11 shows a measurement process for measuring the dimensions of the second weld layer 12 made of the second metal. Based on the measurement, the cap 1 is manufactured at the factory. The height and width of a plurality of positions of the second weld layer 12 made of the second metal with respect to the reference plane (plane orthogonal to the axis of the instrument tube: usually a horizontal plane) 33 are measured. Further, the shape is measured.
[0036]
FIG. 12 shows a manufacturing process for manufacturing the cap 1 in a factory. As shown in FIG. 12A, two cylinders are prepared. The two cylinders are both made of SUS316. A spiral line 36 is drawn on one cylinder, and the necessary thickness above the spiral line 36 is scraped off from one cylinder. The 690 alloy is welded to the half-circumferential portion of the scraped portion. The 690 alloy overlay 37 is made of the second metal. 4 This corresponds to half of the weld layer 13.
[0037]
A spiral line 36 is drawn on another cylinder, and the above-mentioned thickness is scraped off from the other cylinder at a position above the spiral line 36. The 690 alloy is welded to the half of the scraped portion and the portion 37 that is the shrinkage allowance. The 690 alloy overlay 38 is made of a second metal. 4 This corresponds to the other half of the weld layer 13. The welding process of the 690 alloy build-up 37 and the 690 alloy build-up 38 is performed in an inert gas 100% atmosphere. Inspection of the groove surface is performed before welding, inspection of the welded part is performed after welding, and dimensional inspection is performed simultaneously.
[0038]
The first semi-finished product 34 formed by the first processing shown in FIG. 12A corresponds to the dimension measured in the step shown in FIG. 11 as shown in FIG. 12B. In addition, the inner diameter processing is performed. The first semi-finished product 34 formed by the first processing shown in FIG. 12A corresponds to the dimension measured in the step shown in FIG. 11 as shown in FIG. 12B. In addition, the inner diameter processing is performed. The upper part of the first semi-finished product 34 ′ formed by the second processing shown in FIG. 12B is cut obliquely as shown in FIG. The upper part of the second semi-finished product 35 ′ formed by the second processing shown in FIG. 12B is cut obliquely as shown in FIG.
[0039]
As shown in FIG. 12D, the third semi-finished product 34 ″ formed by the third processing shown in FIG. 12C is shown in FIG. 11 in consideration of the shrinkage allowance due to welding. Half processing and longitudinal groove processing are performed so as to correspond to the dimensions measured in the process. For the third semi-finished product 35 ″ formed by the third processing shown in FIG. As shown in FIG. 12 (d), the splitting process and the longitudinal groove machining) are performed so as to correspond to the dimensions measured in the process shown in FIG. .
[0040]
FIG. 13 shows an assembly process for assembling the cap 1 by welding. The fourth semi-finished products 39 ″ and 41 ″ processed as shown in FIG. 12D are abutted so as to surround the conduit tube 8, and one fourth semi-finished product 39 ″ and the other fourth semi-finished product 41 are joined together. As shown in FIGS. 14 (a) and 14 (b), “” is assembled to the cylindrical cap 1 by being welded by butt longitudinal welding in an arrangement state surrounding the conduit tube 8. The welding material used for the butt longitudinal welding part 42 is SUS316 which is the same as the main body material of the cap 1. The welding process is performed in a 100% inert gas atmosphere. The inert gas 100% atmosphere is formed when the inert gas introduced from the gas introduction cylinder 16 surrounds the periphery of the welding site.
[0041]
FIG. 15 shows the second metal second 4 The welding process of the butt welding for completion of the welding layer 13 is shown. Part of the cap 1 is an incomplete, second split second metal second 4 As shown in FIG. 16, the weld layer 13 is joined by butt welding at the half-crack joint portion. The welding material used for the butt longitudinal welded portion 43 between the longitudinal groove surfaces is a second metal-made second material. 4 It is 690 alloy which is the same as the material of the weld layer 13. The welding process is performed in a 100% inert gas atmosphere. The inert gas 100% atmosphere is formed when the inert gas introduced from the gas introduction cylinder 16 surrounds the periphery of the welding site.
[0042]
FIG. 17 shows a temporary joining step in which the cap 1 is temporarily joined to the second metal second weld layer 12. The cap 1 is lifted, and the top surface of the cap 1 and the second metal second 4 The top surface of the weld layer 13 is joined to the lower surface of the second metal second weld layer 12. Second metal made 4 The cap 1 is temporarily joined to the second metal second weld layer 12 by the temporary weld portion 44 straddling the lower surface of the weld layer 13 and the second metal second weld layer 12.
[0043]
FIG. 18 shows a temporary joining step in which the seal ring 15 is temporarily joined between the seal ring 15 and the safe end 7 which is a part of the cap 1. Half-cracked seal ring forming semi-cylinders 15-1 and 15-2 are mounted in an annular space formed between the safe end 7 and the cap 1. The temporary joining between the seal ring forming semi-cylinders 15-1 and 15-2 and the cap 1 is a joining by temporary welding. These welding processes are performed in an atmosphere of 100% inert gas. The inert gas 100% atmosphere is formed by the inert gas introduced from the gas introduction cylinder 16 surrounding the welded portion. In this temporary joining process, the seal ring 15 is in a half-cracked state, and the butt welding target portion 45 is not welded as shown in FIG.
[0044]
FIG. 20 shows the main joining step between the second metal second weld layer 12 and the cap 1. The cap 1 temporarily joined by the temporary weld 44 shown in FIG. 17 is finally joined to the second metal second weld layer 12. The lower surface of the second metal second weld layer 12 and the second metal second 4 The second metal-made second part which is the main welding part straddling the outer peripheral surface of the weld layer 13 3 The material used for the weld layer 14 is the same as that of the second metal second weld layer 12 and the second metal second weld layer 12. 4 It is 690 alloy which is the same as the material of the weld layer 13.
[0045]
The welding process is performed in a 100% inert gas atmosphere. The inert gas 100% atmosphere is formed by the inert gas introduced from the gas introduction cylinder 16 surrounding the periphery of the welding site or entering the welding joint surface. The seal ring 15 is subjected to a flaw detection test and a dimensional inspection.
[0046]
FIG. 21 shows a main joining process in which the seal ring 15 is finally joined to the safe end 7 and the cap 1. As shown in FIG. 22, the main welding portion 46 is embedded in the butt welding target portion 45 shown in FIG. 18 by longitudinal butt welding. This welding is performed in a 100% inert gas atmosphere. The main welding portion 46 is subjected to ultrasonic flaw detection. Such a flaw detection inspection is executed after the fillet welding described later is executed and after the contact medium for UT and the liquid of PT do not enter the welded portion.
[0047]
FIG. 23 shows a joining process between the seal ring 15 and the safe end 7. Fillet welding over the lower surface of the seal ring 15 and the outer peripheral surface of the safe end 7 is performed in an inert gas 100% atmosphere, and as shown in FIG. The material of the first seal welding portion 26 is equivalent to SUS316l or SUS316l. FIG. 24 shows a joining process between the safe end 7 and the seal ring 15. Fillet welding over the lower surface of the cap 1 and the outer peripheral surface of the seal ring 15 is performed in an inert gas 100% atmosphere, and as shown in FIG. The material of the second seal welding portion 27 is equivalent to SUS316l or SUS316l.
[0048]
As shown in FIG. 25, the inert gas or degassed water is introduced into the annular space 18 through the gas introduction cylinder 16, and the sealing on-off valve 29 is closed to deactivate the inert gas or degassed water. Encapsulation is performed.
[0049]
If a leak is found in an instrument tube penetrating part (penetrating body penetrating part) at the time of inspection of the reactor bottom of an active reactor, the construction of the method for repairing a furnace bottom penetrating part according to the present invention is performed. The above-mentioned welding is performed by performing visual inspection or various flaw detection inspections on the welding target portion, and various flaw detection inspections are performed for confirmation regarding the welding, and the soundness of the construction is confirmed.
[0050]
【The invention's effect】
The sealing structure of the furnace bottom penetrating part and the method of sealing the furnace bottom penetrating part according to the present invention ensure the prevention of leakage and enable sealing or sealing repair in a short construction period.
[Brief description of the drawings]
FIG. 1 is an oblique projection showing an embodiment of a sealing structure for a furnace bottom through portion according to the present invention.
FIG. 2 is a cross-sectional view showing a part of FIG. 1;
FIG. 3 is a cross-sectional plan view of FIG. 1;
FIG. 4 is an oblique projection showing a lid cylinder.
FIG. 5 is a cross-sectional view showing a part of FIG. 1;
FIG. 6 is an oblique projection view showing a part of FIG. 5;
FIG. 7 is a cross-sectional view showing an initial step of an embodiment of a method for sealing a furnace bottom penetration according to the present invention.
FIG. 8 is a cross-sectional view showing a step subsequent to that in FIG. 7;
FIG. 9 is a cross-sectional view showing the next step of FIG. 8;
FIG. 10 is a cross-sectional view showing a step subsequent to FIG. 9;
FIG. 11 is a cross-sectional view showing a step subsequent to FIG. 10;
FIGS. 12A, 12B, 12C, and 12D are cross-sectional views respectively showing a plurality of steps subsequent to FIG.
13 is a cross-sectional view showing a step subsequent to FIG. 12. FIG.
14A and 14B are cross-sectional views cut at two positions in FIG. 13, respectively.
FIG. 15 is a cross-sectional view showing the next step of FIG. 13;
FIG. 16 is a cross-sectional view of FIG.
FIG. 17 is a cross-sectional view showing a step subsequent to FIG. 15;
FIG. 18 is a cross-sectional view showing a step subsequent to FIG. 17;
FIG. 19 is a cross-sectional view of FIG.
FIG. 20 is a cross-sectional view showing a step subsequent to FIG. 19;
FIG. 21 is a cross-sectional view showing a step subsequent to FIG. 20;
FIG. 22 is a cross-sectional view of FIG.
FIG. 23 is a cross-sectional view showing a step subsequent to FIG. 21;
FIG. 24 is a cross-sectional view showing a step subsequent to FIG. 23;
FIG. 25 is a cross-sectional view showing a step subsequent to FIG. 24;
FIG. 26 is an oblique axis projection view showing the outer appearance of the reactor vessel.
[Explanation of symbols]
1 ... Cap
2 ... Furnace bottom
3 ... Penetration body (instrumentation cylinder)
4 ... exposed area
11 ... 1st weld layer
12 ... Second weld layer
13th 4 Weld layer
14th 3 Weld layer
15 ... Seal ring
16 ... Gas supply pipe
18 ... annular space (gap)
19 ... 1st half crack cap
21 ... 2nd half crack cap
29 ... Open / close valve
34 ... 2nd 1st semi-finished product
34 '... 3rd 1st semi-finished product
35 ... 2nd second semi-finished product
35 '... the third second product
37 ... 1st half circumference weld layer
38 ... 2nd half circumference welding layer

Claims (9)

A penetrating body that penetrates the bottom of the reactor,
Covering body for covering from the outer bottom surface the joining site where the penetrating body and the furnace bottom are joined
And
There is a closed space between the covering and the penetrating body,
The covering body is
An annular weld layer covering the joining site and the lower surface of the furnace bottom;
A cap that surrounds the exposed portion of the penetrating body that penetrates the weld layer downward and is exposed below the weld layer;
Forming a seal ring mounted in an annular space between the outer peripheral surface of the lower end portion of the exposed portion and the inner peripheral surface of the lower end portion of the cap;
Sealing structure of the bottom penetration. A penetrating body that penetrates the bottom of the reactor,
Covering body for covering from the outer bottom surface the joining site where the penetrating body and the furnace bottom are joined
And
There is a closed space between the covering and the penetrating body,
The space is filled with an inert gas
Sealing structure of the bottom penetration. A penetrating body that penetrates the bottom of the reactor,
Covering body for covering from the outer bottom surface the joining site where the penetrating body and the furnace bottom are joined
And
The covering is
An annular first weld layer that directly covers the joining site and the lower surface of the furnace bottom;
A cap penetrating the first weld layer in the lower direction and surrounding an exposed portion of the penetrator exposed below the first weld layer;
A second weld layer joined to the lower surface of the first weld layer;
A third weld layer fixed to the outer peripheral surface of the upper end portion of the cap and the second weld layer;
Forming a seal ring mounted in an annular space between the outer peripheral surface of the lower end portion of the exposed portion and the inner peripheral surface of the lower end portion of the cap;
Sealing structure of the bottom penetration. The material of the first weld layer is 600 alloy, the material of the second weld layer is 690 alloy, and the material of the third weld layer is 690 alloy.
The sealing structure of the furnace bottom penetration part of Claim 3 . The covering further forms a fourth weld layer that directly joins the outer peripheral surface of the upper end portion of the cap;
The third weld layer is joined to the upper end portion of the cap via the fourth weld layer ,
Material prior Symbol first weld layer is Alloy 600, the material of the second welding layer is 690 alloy, the material of the third weld layer is 690 alloy, the fourth weld layer is a 690 alloy
The sealing structure of the furnace bottom penetration part of Claim 3 . The covering is
A fifth weld layer joined to the outer peripheral surface of the lower end portion of the exposed portion and the lower end surface of the seal ring;
A sixth weld layer that joins the outer peripheral surface of the seal ring and the lower end surface of the cap is further formed.
The sealing structure of the furnace bottom penetration part of Claim 1 selected from Claims 3-5 . Further comprising a gas supply pipe coupled to the cap;
The inside of the gas supply pipe is connected to the annular space.
The sealing structure of the furnace bottom penetration part of Claim 3 . 6. The furnace bottom penetrating sealing structure according to claim 5 , further comprising an on-off valve interposed in the gas supply pipe. The sealing structure of a furnace bottom penetration part according to claim 7 or 8 , wherein an inert gas is supplied to the annular space via the gas supply pipe.

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