Reactor internals irradiation sample holder structure for shielding fast neutrons

Abstract

The present invention relates to the technical field of pressurized water type nuclear power station reactor top structures, and provides a reactor internal irradiation sample holder structure for shielding fast neutrons, the reactor internal irradiation sample holder structure comprises a bottom plate and a cover plate, one side of the cover plate is provided with an accommodating groove, the cover plate and the bottom plate are connected through a fastener so as to fix an irradiation sample between the accommodating groove and the bottom plate, the bottom plate comprises a base body, a shielding plate and a sealing plate, a groove is formed in one side of the base body, the sealing plate is fixedly connected with the base body and seals the groove, and the shielding plate is placed in the groove. According to the invention, the neutron irradiation dose of the irradiation sample can be adjusted by replacing the shielding plates with different shielding effects, so that the adjustment of the lead factor is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of the reactor top structure of a pressurized water reactor nuclear power plant, and more particularly, to an irradiation sample rack structure for reactor internals that shields fast neutrons. Background Art

[0002] The reactor pressure vessel of a pressurized water reactor nuclear power plant is an irreplaceable device of the reactor, and its design life determines the life of the reactor. The reactor pressure vessel operates in an environment of high temperature, high pressure and high irradiation. As the operation time increases, the performance of the reactor pressure vessel material will gradually weaken; due to the inconvenience of directly detecting the reactor pressure vessel in a high-irradiation environment, irradiation samples made of the same material as the reactor pressure vessel are provided on the reactor internals, and the irradiation samples are taken out regularly to test their performance, which is used to judge the performance status of the reactor pressure vessel. At the same time, the irradiation samples are closer to the reactor core than the reactor pressure vessel and receive a higher irradiation dose, which can predict the life of the reactor pressure vessel in advance, and this advance amount is called the lead factor.

[0003] The lead factor of the irradiation sample should be able to reflect the performance of the pressure vessel during the entire life cycle of the reactor. The value of the lead factor should not be too large or too small; since the lead factor is mainly determined by the irradiation dose received by the irradiation sample and the dose received by the pressure vessel, when the dose received by the pressure vessel is certain, the value of the lead factor can be adjusted by adjusting the irradiation dose received by the irradiation sample.

[0004] Currently, in all pressurized water reactors, the irradiation samples are placed in an irradiation sample rack, and the irradiation sample rack is generally fixed on the outer side of the basket cylinder of the reactor internals. The irradiation sample rack is mainly composed of a bottom plate and a cover plate, and is fixed on the basket cylinder by bolts. Theoretically, the irradiation dose received by the irradiation sample can be adjusted by adjusting the thickness of the irradiation sample rack, thereby adjusting the value of the lead factor. However, due to the small gap between the basket cylinder and the reactor pressure vessel, the degree to which the thickness of the irradiation sample rack can be increased is very limited. Therefore, when the design life of the reactor changes and the lead factor needs to be adjusted, the current structure is difficult to meet the requirements. Summary of the Invention

[0005] The purpose of the present invention is to provide an irradiation sample rack structure for reactor internals that shields fast neutrons, solve the above defects of the prior art, and achieve the adjustment of the lead factor.

[0006] The present invention is achieved through the following technical solutions:

[0007] A structure of an irradiation sample rack for in-core components of a reactor for shielding fast neutrons, comprising a bottom plate and a cover plate. A receiving groove is provided on one side of the cover plate. The cover plate and the bottom plate are connected by fasteners to fix the irradiation sample between the receiving groove and the bottom plate. The bottom plate includes a base body, a shielding plate, and a sealing plate. A groove is provided on one side of the base body. The sealing plate is fixedly connected to the base body to close the groove. The shielding plate is placed in the groove to adjust the neutron irradiation dose received by the irradiation sample by replacing shielding plates with different shielding effects, thereby realizing the adjustment of the advance factor.

[0008] Optionally, a plurality of first elastic members are fixedly provided at the bottom of the groove, and a plurality of second elastic members are fixedly provided on one side of the sealing plate. The irradiation sample is pressed between the first elastic members and the second elastic members. With such a setting, not only can the shielding plate be fixed to prevent the shielding plate from colliding inside the groove when the irradiation sample mounting rack moves with the hanging basket, but also the presence of the first elastic members and the second elastic members can accommodate the thermal expansion difference between the bottom plate and the shielding plate.

[0009] Optionally, both the first elastic member and the second elastic member are springs.

[0010] Optionally, the sealing plate is welded to the base body.

[0011] Optionally, a first snap ring is provided at one end of the receiving groove, and a second snap ring is provided at the other end of the receiving groove to realize the fixation and positioning of the irradiation sample.

[0012] Optionally, a first positioning step is provided at one end of the base body, and the inner end of the first snap ring abuts against the first positioning step to facilitate the installation and positioning of the first snap ring; a second positioning step is provided at the other end of the base body, and the inner end of the second snap ring abuts against the second positioning step to facilitate the installation and positioning of the second snap ring.

[0013] Optionally, both the first snap ring and the second snap ring are welded to the base body or the cover plate to prevent the first snap ring and the second snap ring from falling off.

[0014] Optionally, the shielding plate includes a plurality of sub-plates, and the plurality of sub-plates are stacked in sequence and fixedly connected between adjacent sub-plates.

[0015] Optionally, the shielding plate is a tungsten plate.

[0016] Optionally, the shielding plate is a lead plate.

[0017] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0018] 1. In the present invention, based on the prior art, the bottom plate is divided into a base body, a shielding plate, and a sealing plate. The shielding plate is enclosed in the upper groove of the base body by the sealing plate. By replacing the shielding plate with different shielding effects (i.e., different materials and / or different thicknesses), the neutron irradiation dose received by the irradiated sample can be adjusted, thereby adjusting the lead factor so that the reactor pressure vessel leads to reach the design requirement value.

[0019] 2. In the present invention, the shielding plate is sealed inside the groove on the base body to prevent the shielding plate from contacting the reactor coolant, that is, to prevent the elements contained in the shielding plate from invading the coolant.

[0020] 3. In the present invention, a plurality of first elastic members are fixedly arranged at the bottom of the groove, and a plurality of second elastic members are fixedly arranged on one side of the sealing plate. The irradiated sample is pressed between the first elastic member and the second elastic member. With such a setting, not only can the shielding plate be fixed to prevent the shielding plate from colliding inside the groove when the irradiated sample mounting rack moves with the hanging basket, but also the existence of the first elastic member and the second elastic member can adapt to the thermal expansion difference between the bottom plate and the shielding plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of an in-core component irradiation sample rack structure for shielding fast neutrons provided by the present invention;

[0022] Figure 2 is an exploded view of an in-core component irradiation sample rack structure for shielding fast neutrons provided by the present invention;

[0023] Figure 3 is a cross-sectional view of the bottom plate;

[0024] Reference numerals: 1 - base body, 101 - first positioning step, 102 - second positioning step, 2 - shielding plate, 3 - sealing plate, 4 - cover plate, 5 - first snap ring, 6 - second snap ring, 7 - first elastic member, 8 - second elastic member. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] Embodiment 1

[0026] An in-core component irradiation sample rack structure for shielding fast neutrons includes a bottom plate and a cover plate 4. A receiving groove is provided on one side of the cover plate 4. In practical applications, the shape of the receiving groove is set according to the shape of the irradiated sample. For example, if the irradiated sample is cylindrical, then in this embodiment, the cross-section of the receiving groove perpendicular to the length direction is arc-shaped, and the bottom of the receiving groove is open. After the cover plate 4 and the bottom plate are connected by fasteners (such as screws, bolts, etc.), the irradiated sample is pressed between the receiving groove and the bottom plate.

[0027] In this embodiment, a first snap ring 5 is provided at one end of the receiving groove, and a second snap ring 6 is provided at the other end of the receiving groove. The first snap ring 5 and the second snap ring 6 work together to fix and position the irradiated sample. It is easy to understand that the shapes of the first snap ring 5 and the second snap ring 6 are adapted to the shape of the receiving groove. Based on the fact that the cross-section of the receiving groove perpendicular to the length direction is arc-shaped in this embodiment, the first snap ring 5 and the second snap ring 6 should be cylindrical. In addition, the number of receiving grooves can be set to one or more. For example, two receiving grooves are provided in this embodiment. On this basis, it should be understood that the number of the first snap rings 5 and the number of the second snap rings 6 should also be two.

[0028] Further, a first positioning step 101 is provided at one end of the base body 1, and the inner end of the first snap ring 5 abuts against the first positioning step 101 to position the first snap ring 5; a second positioning step 102 is provided at the other end of the base body 1, and the inner end of the second snap ring 6 abuts against the second positioning step 102 to position the second snap ring 6. On the above basis, the first snap ring 5 and the second snap ring 6 are in interference fit with the first receiving groove. Further, in this embodiment, both the first snap ring 5 and the second snap ring 6 are welded to the cover plate 4 to prevent the first snap ring 5 and the second snap ring 6 from falling off. In other embodiments, the first snap ring 5 and the second snap ring 6 can also be welded to the base body 1.

[0029] The bottom plate includes a base body 1, a shielding plate 2 and a sealing plate 3. A groove is provided on one side of the base body 1. The specific shape of the groove is not specifically limited. For example, the groove can be a rectangular structure or a kidney-shaped structure with arc-shaped ends at both ends. The shielding plate 2 is placed in the groove, and the sealing plate 3 closes the groove, that is, isolates the shielding plate 2 inside the groove to prevent the shielding plate 2 from contacting the reactor coolant, that is, to prevent the elements contained in the shielding plate 2 from invading the coolant.

[0030] The sealing plate 3 is fixedly connected to the base body 1. As an option, in this embodiment, the sealing plate 3 is welded to the base body 1. In actual application, the contact between the sealing plate 3 and the base body 1 is fully welded to ensure that the groove is completely sealed. In other embodiments, the sealing plate 3 and the base body 1 can also be connected by fasteners (such as screws, rivets, etc.), and sealing measures are taken at the connection.

[0031] In actual application, the neutron irradiation dose received by the irradiated sample is adjusted by replacing the shielding plate 2 with different shielding effects, so as to adjust the lead factor. It should be understood that "different shielding effects" can be achieved by different materials, or by different thicknesses, or by a combination of different materials and different thicknesses. In addition, it is easy to understand that when the sealing plate 3 is easy to disassemble, only the shielding plate 2 can be replaced to adjust the neutron irradiation dose received by the irradiated sample; when the sealing plate 3 is welded to the base body 1, the entire bottom plate is replaced.

[0032] In this embodiment, the shielding plate 2 is a tungsten plate, that is, the shielding plate 2 is made of tungsten material. Further, the shielding plate 2 includes a plurality of sub-plates, and the plurality of sub-plates are stacked in sequence and fixedly connected between adjacent sub-plates. The way of fixed connection is not limited. For example, it can be bonding, riveting and other ways. It should be understood that in other embodiments, the shielding plate 2 can of course be only one plate.

[0033] In this embodiment, a number of first elastic members 7 are fixedly arranged at the bottom of the groove, and a number of second elastic members 8 are fixedly arranged on one side of the sealing plate 3. The irradiated sample is pressed between the first elastic member 7 and the second elastic member 8. With such a setting, not only can the shielding plate 2 be fixed to prevent the shielding plate 2 from colliding inside the groove when the irradiated sample mounting rack moves with the hanging basket, but also since the bottom plate is usually made of stainless steel and the shielding plate 2 is made of tungsten plate, there is a thermal expansion difference between the bottom plate and the shielding plate 2. The shielding plate 2 is rigidly pressed in the groove, which easily causes the sealing plate 3 to be expanded. The presence of the first elastic member 7 and the second elastic member 8 can adapt to the thermal expansion difference between the bottom plate and the shielding plate 2 and solve the above problems.

[0034] As an option, in this embodiment, both the first elastic member 7 and the second elastic member 8 are springs. In other embodiments, the first elastic member 7 and the second elastic member 8 can of course be other objects with the same ability.

[0035] Embodiment 2

[0036] A structure of an irradiation sample rack for in-core components of a reactor for shielding fast neutrons includes a bottom plate and a cover plate 4. A receiving groove is provided on one side of the cover plate 4. In practical applications, the shape of the receiving groove is set according to the shape of the irradiated sample. For example, if the irradiated sample is cylindrical, then in this embodiment, the cross-section of the receiving groove perpendicular to the length direction is arc-shaped. The bottom of the receiving groove is open. After the cover plate 4 and the bottom plate are connected by fasteners (such as screws, bolts, etc.), the irradiated sample is pressed between the receiving groove and the bottom plate.

[0037] In this embodiment, a first clamping ring 5 is provided at one end of the receiving groove, and a second clamping ring 6 is provided at the other end of the receiving groove. The first clamping ring 5 and the second clamping ring 6 act together to realize the fixation and positioning of the irradiated sample. It is easy to understand that the shapes of the first clamping ring 5 and the second clamping ring 6 are adapted to the shape of the receiving groove. Based on the fact that the cross-section of the receiving groove perpendicular to the length direction is arc-shaped in this embodiment, the first clamping ring 5 and the second clamping ring 6 should be cylindrical. In addition, the number of receiving grooves can be set to one or more. For example, two receiving grooves are provided in this embodiment. On this basis, it should be understood that the number of the first clamping ring 5 and the number of the second clamping ring 6 should also be two.

[0038] Further, one end of the base body 1 is provided with a first positioning step 101, and the inner end of the first snap ring 5 abuts against the first positioning step 101 to realize the positioning of the first snap ring 5; the other end of the base body 1 is provided with a second positioning step 102, and the inner end of the second snap ring 6 abuts against the second positioning step 102 to realize the positioning of the second snap ring 6. On this basis, the first snap ring 5 and the second snap ring 6 are in interference fit with the first accommodating groove. Further, in this embodiment, both the first snap ring 5 and the second snap ring 6 are welded to the cover plate 4 to prevent the first snap ring 5 and the second snap ring 6 from falling off. In other embodiments, the first snap ring 5 and the second snap ring 6 can also be welded to the base body 1.

[0039] The bottom plate includes a base body 1, a shielding plate 2 and a sealing plate 3. One side of the base body 1 is provided with a groove, and the specific shape of the groove is not specifically limited. For example, the groove can be a rectangular structure or a kidney-shaped structure with both ends being arc-shaped. The shielding plate 2 is placed in the groove, and the sealing plate 3 closes the groove, that is, isolates the shielding plate 2 inside the groove to prevent the shielding plate 2 from contacting the reactor coolant, that is, to prevent the elements contained in the shielding plate 2 from invading the coolant.

[0040] The sealing plate 3 is fixedly connected to the base body 1. As an option, in this embodiment, the sealing plate 3 is welded to the base body 1. In actual application, the contact part between the sealing plate 3 and the base body 1 is fully welded to ensure that the groove is completely sealed. In other embodiments, the sealing plate 3 and the base body 1 can also be connected by fasteners (such as screws, rivets, etc.), and sealing measures are taken at the connection part.

[0041] In actual application, the neutron irradiation dose received by the irradiated sample is adjusted by replacing the shielding plate 2 with different shielding effects, so as to realize the adjustment of the lead factor. It should be understood that "different shielding effects" can be achieved by different materials, or by different thicknesses, or by a combination of different materials and different thicknesses. In addition, it is easy to understand that when the sealing plate 3 is easy to disassemble, only the shielding plate 2 can be replaced to adjust the neutron irradiation dose received by the irradiated sample; when the sealing plate 3 is welded to the base body 1, the whole bottom plate is replaced.

[0042] In this embodiment, the shielding plate 2 is a lead plate, that is, the shielding plate 2 is made of lead material. Further, the shielding plate 2 includes a plurality of sub-plates, and the plurality of sub-plates are stacked in sequence and fixedly connected between adjacent sub-plates. The fixed connection method is not limited. For example, it can be by bonding, riveting, etc. It should be understood that in other embodiments, the shielding plate 2 can of course also be just one plate.

[0043] In this embodiment, a plurality of first elastic members 7 are fixedly arranged at the bottom of the groove, and a plurality of second elastic members 8 are fixedly arranged on one side of the sealing plate 3. The irradiated sample is pressed between the first elastic member 7 and the second elastic member 8. With such an arrangement, not only can the shielding plate 2 be fixed to prevent the shielding plate 2 from colliding inside the groove when the irradiated sample mounting rack moves with the hanging basket, but also since the bottom plate is usually made of stainless steel and the shielding plate 2 is made of lead plate, there is a thermal expansion difference between the bottom plate and the shielding plate 2. The shielding plate 2 is rigidly pressed in the groove, which easily causes the sealing plate 3 to be expanded. The presence of the first elastic member 7 and the second elastic member 8 can adapt to the thermal expansion difference between the bottom plate and the shielding plate 2, thus solving the above problems.

[0044] As an option, in this embodiment, both the first elastic member 7 and the second elastic member 8 are springs. In other embodiments, the first elastic member 7 and the second elastic member 8 can of course also be other objects with the same capabilities.

[0045] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A structure of an in-core component irradiation sample holder for shielding fast neutrons, comprising a bottom plate and a cover plate. A receiving groove is provided on one side of the cover plate. The cover plate and the bottom plate are connected by fasteners to fix the irradiation sample between the receiving groove and the bottom plate. It is characterized in that, The bottom plate includes a base body, a shielding plate, and a sealing plate. A groove is provided on one side of the base body. The sealing plate is fixedly connected to the base body and closes the groove. The shielding plate is placed in the groove to adjust the neutron irradiation dose received by the irradiated sample by replacing shielding plates with different shielding effects, thereby realizing the adjustment of the lead factor.

2. The irradiation sample rack structure for the in-core components of a reactor used to shield fast neutrons according to claim 1, wherein A plurality of first elastic members are fixedly arranged at the bottom of the groove, and a plurality of second elastic members are fixedly arranged on one side of the sealing plate. The irradiated sample is pressed between the first elastic members and the second elastic members.

3. The in-core component irradiation sample rack structure for shielding fast neutrons according to claim 2, wherein Both the first elastic member and the second elastic member are springs.

4. The in-core component irradiation sample rack structure for shielding fast neutrons according to claim 1, characterized in that, The sealing plate is welded to the base body.

5. The irradiation sample rack structure for in-reactor components for shielding fast neutrons according to claim 1, characterized in that, A first snap ring is provided at one end of the accommodation groove, and a second snap ring is provided at the other end of the accommodation groove.

6. The in-core component irradiation sample rack structure for shielding fast neutrons according to claim 5, characterized in that, A first positioning step is provided at one end of the base body, and the inner end of the first snap ring abuts against the first positioning step; a second positioning step is provided at the other end of the base body, and the inner end of the second snap ring abuts against the second positioning step.

7. The irradiation sample rack structure for shielding fast neutrons in the reactor internal structure according to claim 5, characterized in that, Both the first snap ring and the second snap ring are welded to the base body or the cover plate.

8. The irradiation sample rack structure for shielding fast neutrons in the reactor internals according to any one of claims 1-7, characterized in that, The shielding plate includes a plurality of sub-plates, and the plurality of sub-plates are stacked in sequence and fixedly connected between adjacent sub-plates.

9. The irradiation sample rack structure for a reactor internals used to shield fast neutrons according to any one of claims 1-7, characterized in that, The shielding plate is a tungsten plate.

10. The irradiation sample rack structure for shielding fast neutrons in the reactor internal structure according to any one of claims 1-7, characterized in that, The shielding plate is a lead plate.

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