Test device for corrosion performance of containment steel lining and stud welding area

Abstract

The present invention discloses a testing device for the post-corrosion performance of the steel lining and stud welding area of ​​a containment, comprising: a steel lining test piece, comprising a steel lining plate, studs welded on the steel lining plate, and concrete poured between the steel lining plates, the steel lining plate and the stud welding area are connected with a wire, and the local corrosion of the steel lining plate and the stud welding area is achieved through the wire through electrochemical accelerated corrosion; and a loading device, provided with a clamp connected to the steel lining test piece, and a load is applied to the steel lining test piece through the clamp. Compared with the prior art, in the testing device for the post-corrosion performance of the steel lining and stud welding area of ​​the containment of the present invention, the steel lining plate and the stud are welded according to the requirements of the nuclear power plant containment welding, the wire is reserved in the steel lining plate and the stud welding area, concrete is poured between the steel lining plates, and the local corrosion of the steel lining plate and the stud welding area is achieved through electrochemical corrosion, and the mechanical properties of the steel lining plate and the stud welding area after corrosion can be tested by loading through the loading device.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power, and more specifically, relates to a testing device for the post-corrosion performance of a containment steel lining and a stud welding zone. Background Art

[0002] Nuclear energy has a large unit energy and abundant resource reserves. It is recognized as an economical, safe and clean energy that can replace conventional energy on a large scale. As my country's nuclear power plant construction enters a period of rapid development and nuclear power plants are developing from coastal areas to inland areas, the safety of nuclear power plants must be given high attention.

[0003] As the last barrier of nuclear safety-related measures, whether the containment can fully cope with the high-energy loads (manifested as high temperature, high pressure and high humidity) under severe accident conditions, and whether it can ensure that no radioactive material leaks under high-energy loads or control the leakage to a level with little impact on the environment, has become the performance that people are most concerned about. The sealing performance of the containment steel lining directly determines whether the safety barrier of the nuclear power unit is complete, and the tearing characteristics of the steel lining are directly related to its sealing performance. If the containment structure cannot withstand the high-energy load under the beyond-design basis accident and causes the steel lining to tear, it will cause the containment's sealing to fail, and radioactive material leakage is bound to occur.

[0004] A large number of investigations have shown that steel lining corrosion is a key factor affecting the containment's sealing performance, and corrosion will directly lead to a significant reduction in the mechanical properties of the steel lining. Although a certain degree of corrosion is allowed in the design, due to the thin thickness of the steel lining (generally around 6 mm), corrosion that exceeds the allowable range can easily cause the steel lining to tear in a serious accident, posing a potential threat to the safe operation of the nuclear power plant.

[0005] The steel lining of the containment is anchored to the concrete through studs and angle steels. The welding area between the studs and the steel lining is a stress concentration area, which will cause stress redistribution in the steel lining under load. Under the action of severe accident loads exceeding the design basis, the interaction between the steel lining of the containment and the concrete, coupled with the influence of the shear force of the studs on the steel lining, leads to a very complex stress state of the steel lining. The stress concentration in the welding area and the influence of the shear force of the studs may cause the steel lining to tear at a lower stress level. If the steel lining in the welding area with the studs rusts, the risk of the steel lining tearing due to the shear force of the studs will inevitably increase further.

[0006] At present, there is still a lack of research on the mechanical properties of the welded area between the steel lining and the studs after corrosion, and the influence of the stud shear force on the tearing mechanism of the corroded steel lining is still unclear. Due to the particularity of the containment structure of nuclear power plants, it is urgent to design a test device for the corrosion performance of the welded area between the steel lining and the studs in the containment that can be performed under laboratory conditions to study the above problems, so as to obtain reliable test data and provide a reference for the design, inspection and maintenance of the steel lining of the containment of nuclear power plants. Summary of the invention

[0007] The object of the present invention is to overcome at least one defect in the prior art and provide a test device for the post-corrosion performance of the containment steel lining and stud welding zone that can be performed under laboratory conditions.

[0008] In order to achieve the above object, the present invention provides a testing device for the corrosion performance of the containment steel lining and stud welding area, which comprises:

[0009] A steel lining test piece, the steel lining test piece comprising a steel lining plate, studs welded to the steel lining plate according to the containment welding requirements of a nuclear power plant, and concrete poured between the steel lining plates, wherein the welding area between the steel lining plate and the studs is connected with a wire, and the local corrosion of the welding area between the steel lining plate and the studs is achieved through electrochemical accelerated corrosion of the wire; and

[0010] The loading device is provided with a fixture connected to the steel lining specimen, and a load is applied to the steel lining specimen through the fixture.

[0011] According to one embodiment of the testing device for the post-corrosion performance of the containment steel lining and stud welding area of ​​the present invention, the steel lining plates are symmetrically arranged on both sides of the concrete, the roots of the studs are symmetrically welded to the middle of the steel lining plates, and the ends of the studs are buried in the concrete.

[0012] According to an embodiment of the testing device for the post-corrosion performance of the containment steel lining and stud welding zone of the present invention, the steel lining specimen is provided with prestressed threaded steel bars symmetrically embedded in the upper and lower ends of the concrete.

[0013] According to one embodiment of the testing device for the post-corrosion performance of the containment steel lining and stud welding area of ​​the present invention, steel base plates are installed at the upper and lower ends of the steel lining specimen, and through holes are provided on the steel base plates. After the prestressed threaded steel bars pass through the through holes, the upper and lower sides are fixed with nuts.

[0014] According to an embodiment of the testing device for the post-corrosion performance of the containment steel lining and stud welding zone of the present invention, a displacement sensor is provided on the steel bottom plate.

[0015] According to an embodiment of the testing device for the post-corrosion performance of the containment steel lining and stud welding area of ​​the present invention, a steel top plate is welded to the steel bottom plate, the steel top plate is provided with a mounting hole, and a steel tie rod is installed in the mounting hole.

[0016] According to an embodiment of the testing device for the post-corrosion performance of the containment steel lining and stud welding area of ​​the present invention, the steel top plate is provided with a hemispherical mounting hole, and the bottom end of the steel tie rod is a hemispherical shape matching the hemispherical mounting hole.

[0017] According to an embodiment of the testing device for the post-corrosion performance of the containment steel lining and stud welding zone of the present invention, the hemispherical bottom end of the steel tie rod can rotate freely in the hemispherical mounting hole of the steel top plate.

[0018] According to one embodiment of the testing device for the post-corrosion performance of the containment steel lining and stud welding area of ​​the present invention, a load sensor is connected to the steel tie rod, the steel tie rod extending out of the steel top plate is provided with an external thread, the load sensor is correspondingly provided with an internal thread, and the load sensor is installed on the steel tie rod through a threaded connection.

[0019] According to an embodiment of the testing device for the post-corrosion performance of the containment steel lining and stud welding zone of the present invention, a threaded steel bar is provided on the top of the load sensor for connecting with the clamp of the loading device.

[0020] In addition, the present invention also provides a method for preparing a steel lining specimen for post-corrosion performance testing of a containment steel lining and a stud welding zone, which comprises the following steps:

[0021] S1: providing a pair of steel lining plates, and welding the studs to the middle of the pair of steel lining plates respectively according to the welding process requirements of the steel lining plates and studs of the containment of a nuclear power plant;

[0022] S2: uniformly coating the steel lining plate and the stud welded in step S1 with metal anti-rust paint and epoxy resin in sequence, removing the anti-rust paint and epoxy resin on the stud welding area after the epoxy resin is hardened, and connecting the wires in the welding area where the epoxy resin is removed;

[0023] S3: making a mold and reserving through holes on the mold, fixing the steel lining plates welded with studs in step S2 on both sides of the mold, passing the prestressed threaded bars through the through holes reserved on the mold and sealing the through holes with glass glue, and pouring concrete into the mold to obtain a steel lining test piece; and

[0024] S4: After wet water curing the steel lining specimen obtained in step S3, the steel lining specimen is electrochemically corroded to obtain a steel lining specimen for testing the post-corrosion performance of the containment steel lining and the stud welding area.

[0025] According to an improvement of the method for preparing steel lining specimens for post-corrosion performance testing of the welding area between the containment steel lining and the studs of the present invention, after completing the welding in step S1, non-destructive testing is performed on the weld between the steel lining plate and the studs.

[0026] According to an improvement of the method for preparing a steel lining specimen for testing the post-corrosion performance of the containment steel lining and stud welding zone of the present invention, in step S3, a plurality of prestressed threaded steel bars are provided at intervals at each end of the mold.

[0027] In addition, the present invention also provides a steel lining specimen for testing the performance of the containment steel lining and stud welding area after corrosion, which is obtained by using the preparation method of the steel lining specimen for testing the performance of the containment steel lining and stud welding area after corrosion of the present invention.

[0028] Compared with the prior art, in the testing device for the post-corrosion performance of the containment steel lining and stud welding area of ​​the present invention, the steel lining plate and the stud are welded according to the containment welding requirements of the nuclear power plant, wires are reserved in the steel lining plate and stud welding area, concrete is poured between the steel lining plates, local corrosion of the steel lining plate and stud welding area is achieved through electrochemical corrosion, load is applied to the steel lining specimen through a loading device, and the mechanical properties of the steel lining plate and stud welding area after corrosion can be tested under laboratory conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following is a detailed description of the testing device for the corrosion performance of the containment steel lining and stud welding area of ​​the present invention and its technical effects in conjunction with the accompanying drawings and specific embodiments, wherein:

[0030] Figure 1 It is a structural schematic diagram of a testing device for the post-corrosion performance of the containment steel lining and stud welding area of ​​the present invention.

[0031] Figure 2 It is a front view of a steel lining test piece in a testing device for the performance of a containment steel lining and a stud welding zone after corrosion according to the present invention.

[0032] Figure 3 It is a cross-sectional view of a steel lining test piece in a testing device for the performance of a containment steel lining and a stud welding zone after corrosion according to the present invention.

[0033] Figures 4 to 6 They are respectively a front view, a side view and a top view of a steel top plate in a testing device for the post-corrosion performance of a containment steel lining and a stud welding zone of the present invention.

[0034] Figure 7 The present invention is a schematic structural diagram of a steel tie rod in a testing device for the post-corrosion performance of a containment steel lining and a stud welding zone.

[0035] Figure 8 and Fig. 9 The present invention shows a front view and a top view of a steel bottom plate in a testing device for the post-corrosion performance of a containment steel lining and a stud welding zone.

[0036] In the figure:

[0037] 1--Steel lining plate; 2--Studs; 3--Prestressed threaded steel bars; 4--Concrete; 5--Steel top plate; 6--Steel tie rods; 7--Steel bottom plate; 8--Load sensor; 9--Displacement sensor; 10--Nut; 11--Tensile testing machine chuck; 12--Tensile testing machine crossbeam; 13--Tensile testing machine base. DETAILED DESCRIPTION

[0038] In order to make the invention purpose, technical solution and technical effect of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described in this specification are only for explaining the present invention, not for limiting the present invention.

[0039] Please refer to Figures 1 to 9 As shown, the present invention provides a testing device for the corrosion performance of the containment steel lining and stud welding area, which includes:

[0040] A steel lining test piece, the steel lining test piece comprises a steel lining plate 1, studs 2 welded to the steel lining plate 1 according to the containment welding requirements of a nuclear power plant, and concrete 4 poured between the steel lining plates 1, wherein a wire (not shown) is connected to the welding area of ​​the steel lining plate 1 and the stud 2, and local corrosion of the welding area of ​​the steel lining plate 1 and the stud 2 is achieved through electrochemical accelerated corrosion of the wire; and

[0041] The loading device is provided with a clamp connected to the steel lining specimen, and load is applied to the steel lining specimen through the clamp.

[0042] Please refer to Figure 2 and Figure 3 As shown in the figure, the steel liner specimen is made as follows:

[0043] (1) Welding of steel lining plates 1 and studs 2: Two steel lining plates 1 with a thickness of 6 mm were cut according to the size of 350 mm × 300 mm. The steel lining plates 1 were P265GH steel materials adopted in BS EN 10028-2:2017 "European Standard for Steel Plates for Pressure Vessels". According to the welding process and requirements of the steel lining plates 1 and studs 2 of the containment of nuclear power plants, the studs 2 were welded to the middle of the two steel lining plates 1. Each steel lining plate 1 had four studs 2. The transverse and longitudinal spacing of the studs 2 were both 150 mm. The studs 2 were ML15AL studs with a diameter of 8 mm and a length of 80 mm. After welding, the welds were subjected to nondestructive testing.

[0044] (2) Making a mold and fixing the steel lining plate 1 and the prestressed threaded steel bar 3: Make a wooden mold with an inner size of 350 mm × 212 mm × 300 mm. Reserve through holes for the prestressed threaded steel bar 3 on the mold. The through-hole spacing is 100 mm. The prestressed threaded steel bar 3 uses PSB785 type prestressed threaded steel bar with a diameter of 30 mm and a length of 450 mm. Evenly apply metal anti-rust paint on the welded steel lining plate 1 and the stud 2. After the anti-rust paint is dried, evenly apply epoxy resin with a thickness of about 2 mm. After the epoxy resin is hardened, use an angle grinder to remove the anti-rust paint and epoxy resin on the steel lining in the stud welding area. Fix the welded steel lining plate 1 with the stud 2 on both sides of the mold. Pass the prestressed threaded steel bar 3 through the through holes reserved on the mold. Use glass glue to seal the holes. There are three prestressed threaded steel bars 3 at each end of the mold, and the interval between the steel bars at both ends is 30 mm.

[0045] (3) Casting concrete 4 and rusting: Two wires are tied and fixed to each area where the epoxy resin is ground off on the steel lining to complete the rusting of the welding area; then cast concrete 4 and fully vibrate it with a vibrating rod to ensure that the concrete 4 is dense. The concrete strength grade is C50, the length is 350 mm, the width is 300 mm, and the thickness is 200 mm. The mix ratio is cement: admixture: medium sand: small crushed stone: large crushed stone: water: water reducer = 1: 0.137: 1.37: 0.798: 1.862: 0.319: 0.0 16, wherein cement is ordinary Portland cement with a strength grade of 52.5, admixture is S95 slag powder, small crushed stone refers to stone with a particle size of 5-10 mm, large crushed stone refers to stone with a particle size of 10-20 mm, and water reducer is PC-J100 polyhydroxy acid high-efficiency water reducer; after the specimen is cast, the surface is covered with plastic wrap and wet-water cured for 28 days; then the entire specimen is placed in an electrolyte solution pool for electrochemical corrosion. Due to the protection of anti-rust paint and epoxy resin on the steel lining plate 1 and the stud 2, rust only occurs in the welding area of ​​the fixed conductor.

[0046] Please refer to Figure 1 As shown, the matching loading device is connected in the following manner: the steel tie rod 6 is passed through the mounting hole reserved in the middle of the steel top plate 5, and the steel top plate 5 and the steel bottom plate 7 are welded to form a fixture; the prestressed threaded steel bars 3 at the upper and lower ends of the specimen are passed through the through holes on the steel bottom plate 7, and the upper and lower sides of the steel bottom plate 7 are fixed with nuts 10; the load sensor 8 is connected by connecting the thread on the steel tie rod 6 with the threaded hole reserved at the bottom of the load sensor 8, and a threaded steel bar is also connected to the threaded hole reserved at the top of the load sensor 8 for clamping with the testing machine; the threaded steel bar at the top of the load sensor 8 is clamped by the clamp 11 at the top of the testing machine, and the steel tie rod 6 at the bottom of the specimen is clamped by the clamp 11 at the bottom of the testing machine; the displacement sensor 9 is symmetrically placed on the upper surface of the steel bottom plate 7 through a fixed support.

[0047] Once the connection is complete, you can load it. Figure 1 As shown, the base 13 of the tensile testing machine is fixed to the ground, and the force on the crossbeam 12 of the tensile testing machine is transmitted to the prestressed threaded steel bar 3 at the upper end of the specimen through the chuck 11 and the fixture of the tensile testing machine. The prestressed threaded steel bar 3 causes the concrete 4 to be tensile through the bonding force between the concrete 4 and the concrete 4. The tensile deformation of the concrete 4 drives the studs 2 embedded in the concrete 4 to be sheared, and the shear force of the studs 2 is then transmitted to the steel lining plate 1, thereby completing the tensioning of the specimen.

[0048] Please refer to Figures 4 to 6 As shown, the material of the steel top plate 5 is Q235B steel, the length of the steel top plate 5 is 150mm, the width is 150mm, and the thickness is 50mm; the middle of the steel top plate 5 is 25mm away from the bottom surface for a concave hemispherical surface, and the diameter of the hemispherical hole is 48mm; the middle of the steel top plate is 25mm away from the top surface for a circular hole, and the diameter is 42mm; a piece of Q235B steel plate with a length of 150mm, a width of 150mm, and a thickness of 50mm is welded on each side of the steel top plate 5.

[0049] Please refer to Figure 7 As shown, the steel tie rod 6 is made of Q235B steel and has a length of 175 mm. The bottom end of the steel tie rod 6 is hemispherical with a diameter of 48 mm, which matches the diameter of the hemispherical surface at the bottom of the steel top plate. The top end of the steel tie rod 6 is cylindrical with a diameter of 34 mm and has threads.

[0050] Please refer to Figure 8 and Fig. 9 As shown, the material of the steel bottom plate 7 is Q235B steel, with a length of 300 mm, a width of 150 mm, and a thickness of 50 mm. The steel bottom plate 7 is provided with three holes for fixing the prestressed threaded steel bars 3, and the holes are elliptical, with a semi-major axis length of 23 mm and a semi-minor axis length of 19.5 mm.

[0051] Combined with the above detailed description of the embodiments of the present invention, it can be seen that, compared with the prior art, the testing device for the corrosion performance of the containment steel lining and stud welding area of ​​the present invention has the following advantages:

[0052] Firstly, after the steel lining plate 1 and the stud 2 in the steel lining specimen are welded according to the relevant welding requirements of the nuclear power plant containment, a conductor is pre-buried at the connection between the end of the stud 1 and the steel lining plate 2, and then concrete 4 is poured between the two steel plates. After the concrete 4 is hardened, the local corrosion of the welding area between the steel lining plate 1 and the stud 2 can be completed by using the method of electrochemical accelerated corrosion of the conductor. Finally, the mechanical properties of the welded area between the steel lining plate 1 and the stud 2 after corrosion are tested by a tensile test, and the influence of the stud on the tearing mechanism of the steel lining after corrosion of the welded area between the steel lining plate 1 and the stud 2 is obtained, which can provide a reliable test basis for the aging evaluation and sealing evaluation of the steel lining of the containment of a nuclear power plant.

[0053] Secondly, the loading device fixture is easy to manufacture, flexible and convenient to use, and has good loading stability. By setting a hemispherical contact mode on the contact surface of the steel top plate 5 and the steel tie rod 6, the two can rotate flexibly and ensure that the pulling force always remains vertical, which can effectively reduce the influence of eccentricity; the upper inner diameter of the steel top plate 5 is slightly larger than the diameter of the cylindrical end of the steel tie rod 6, which can keep the rotation angle between the two within a suitable range to prevent the lower section from tipping over and damaging equipment and personnel when the specimen breaks; nuts are set at the connection between the steel bottom plate 7 and the prestressed threaded steel bar 3 for fixing, and the nuts can be adjusted to control the loading end to strictly remain horizontal during the test, which can further reduce the influence of eccentricity. The entire loading device has a compact structure, reasonable design, safety and reliability, and can be reused. It can well perform unidirectional tension on the above-mentioned specimens and obtain stable test data.

[0054] According to the above principles, the present invention can also make appropriate changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A testing device for the corrosion performance of the containment steel lining and stud welding area, characterized in that: include: A steel lining test piece, the steel lining test piece comprising a steel lining plate, studs welded to the steel lining plate according to the containment welding requirements of a nuclear power plant, and concrete poured between the steel lining plates, wherein the welding area between the steel lining plate and the studs is connected with a wire, and the local corrosion of the welding area between the steel lining plate and the studs is achieved through electrochemical accelerated corrosion of the wire; and A loading device, wherein the loading device is provided with a fixture connected to the steel lining specimen, and a load is applied to the steel lining specimen through the fixture, wherein the fixture comprises steel bottom plates respectively mounted on the upper and lower ends of the steel lining specimen, steel top plates respectively welded to the steel bottom plates, and steel tie rods respectively mounted in mounting holes provided on the steel top plates; a displacement sensor is provided on the steel bottom plate, a load sensor is provided between the steel tie rod on the upper part of the steel lining specimen and the clamp on the upper part of the tensile testing machine, and the steel tie rod on the lower part of the steel lining specimen is clamped by the clamp on the lower part of the tensile testing machine; The steel top plate is provided with a hemispherical mounting hole, the bottom end of the steel pull rod is hemispherical and matches the hemispherical mounting hole, and the hemispherical bottom end of the steel pull rod can rotate freely in the hemispherical mounting hole of the steel top plate.

2. The testing device for the corrosion performance of the containment steel lining and stud welding area according to claim 1 is characterized in that: The steel lining plates are symmetrically arranged on both sides of the concrete, the roots of the studs are symmetrically welded to the middle of the steel lining plates, and the ends of the studs are embedded in the concrete.

3. The testing device for the corrosion performance of the containment steel lining and stud welding area according to claim 1 is characterized in that: The steel lining specimen is provided with prestressed threaded steel bars symmetrically embedded in the upper and lower ends of the concrete.

4. The testing device for the corrosion performance of the containment steel lining and stud welding area according to claim 3 is characterized in that: The steel bottom plate is provided with a through hole, and the prestressed threaded steel bar is passed through the through hole and then fixed with a nut.

5. The testing device for the corrosion performance of the containment steel lining and stud welding area according to claim 1 is characterized by: The portion of the steel tie rod extending out of the steel top plate is provided with an external thread, and the load sensor is correspondingly provided with an internal thread. The load sensor is installed on the steel tie rod through a threaded connection.

6. The testing device for the corrosion performance of the containment steel lining and stud welding area according to claim 1 is characterized in that: A threaded steel bar is provided on the top of the load sensor for connecting with the clamp on the upper part of the tensile testing machine.

Images