Fast thermal coupling metal hydride reactor core controlled by rotating drum and rotating drum control method

Abstract

The invention belongs to the technical field of nuclear reactor cores, and particularly relates to a fast thermal coupling metal hydride reactor core controlled by a rotating drum and a rotating drum control method, and the reactor core comprises the rotating drum, a reactor core active area, a coolant flow channel, a beryllium oxide reflecting layer and a thermal insulation shielding layer; the coolant flow channel is composed of a coolant flow channel inner barrel and a coolant flow channel outer barrel; the reactor core active area is wrapped by the coolant flow channel inner barrel, and oxide fuel rods and metal hydride fuel rods are arranged in the reactor core active area; the beryllium oxide reflecting layer is arranged on the coolant flow channel outer barrel in a sleeving manner, and the heat preservation shielding layer is arranged on the beryllium oxide reflecting layer in a sleeving manner; a plurality of rotating drums are arranged between the beryllium oxide reflecting layer and the heat preservation shielding layer in the circumferential direction. The oxide fuel rods and the metal hydride fuel rods are arranged in the reactor core active area at the same time, so that the fast thermal coupling design of a reactor core neutron energy spectrum is realized, and the reactivity control value of the rotating drum is improved.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactor core technology, and specifically discloses a fast thermally coupled metal hydride reactor core controlled by a rotating drum and a rotating drum control method. Background Technology

[0002] As a means of controlling the reactivity of nuclear reactors, the rotating drum is arranged around the active zone of the reactor core. By rotating, the neutron absorber material is directed toward the active zone of the core, introducing greater reactivity control value. When the neutron absorber material in the rotating drum moves away from the active zone of the core, the reactivity of the core is released. During the lifespan of the reactor core, the reactivity of the core is stably controlled by adjusting the rotation of the rotating drum around the core.

[0003] In fast-spectrum reactor cores, the mean free path of neutrons is long, and the proportion of neutron leakage is relatively large in relatively small cores. Rotating drums placed outside the active region can generate significant reactivity control value. However, in hot-spectrum reactor cores, due to the very short mean free path of neutrons, even if the active region of the core is small, rotating drums still cannot achieve significant control rod value. Therefore, rotating drums are generally not used as a reactivity control method in hot-spectrum reactor cores.

[0004] In fast-spectrum reactor core design, to increase the value of the rotating drum, the core radial dimension is typically reduced, while neutron leakage towards the rotating drum is increased. However, this design approach limits the core's radial dimension, making it unsuitable for designing cores with slightly larger radial dimensions. Summary of the Invention The purpose of this invention is to provide a fast thermally coupled metal hydride reactor core and a rotating drum controlled by a rotating drum, solving the problem that the reactivity control value of the rotating drum is difficult to improve without changing the core size; the specific solution is as follows: In the first aspect, a fast thermally coupled metal hydride reactor core with rotary drum control is provided, which includes a rotary drum, a core active zone, coolant channels, a beryllium oxide reflector layer and a thermal insulation shielding layer. The coolant flow channel is composed of an inner coolant flow channel tank and an outer coolant flow channel tank; The core active zone is enclosed by the coolant flow channel inner barrel, and oxide fuel rods and metal hydride fuel rods are arranged in the core active zone; The beryllium oxide reflective layer is sleeved on the outer barrel of the coolant flow channel, and the thermal insulation shielding layer is sleeved on the beryllium oxide reflective layer; Several rotating drums are arranged circumferentially between the beryllium oxide reflective layer and the thermal insulation shielding layer.

[0005] Furthermore, the rotating drum is made of beryllium oxide reflective material and boron carbide absorber material. The axial cross-section of the rotating drum is circular. Within the circular area, the fan-shaped region with a central angle of 240 degrees is made of beryllium oxide reflective material, and the remaining fan-shaped region with a central angle of 120 degrees is made of boron carbide absorber material.

[0006] Furthermore, the boron-10 content in the boron carbide absorber material is 90%.

[0007] Furthermore, the beryllium oxide reflective layer (106) and the thermal insulation shielding layer (9) both have an air gap (8) between them and the rotating drum (107).

[0008] Furthermore, the oxide fuel rods and metal hydride fuel rods are uniformly mixed and arranged in the active region of the reactor core.

[0009] Furthermore, the oxide fuel rods are concentrated in the central region of the core active area, while the metal hydride fuel rods are arranged around the periphery of the core active area.

[0010] Furthermore, the number of rotating drums is 8; the core of the oxide fuel rod is UO2 with a fuel enrichment of 5%; the core of the metal hydride fuel rod is UZrH. 1.6 The fuel enrichment level is 20%.

[0011] Furthermore, the number of rotating drums is 12; the core of the oxide fuel rod is UO2 with a fuel enrichment of 6%; the core of the metal hydride fuel rod is UZrH. 1.6 The fuel enrichment level is 23%.

[0012] Furthermore, both the oxide fuel rod and the metal hydride fuel rod consist of a core and a cladding, with the core disposed within the cladding and the space between the core and the cladding filled with helium gas.

[0013] Secondly, a rotating drum control method is provided, applied to the aforementioned fast thermally coupled metal hydride reactor core employing rotating drum control, comprising: When the reactor is shut down, all the boron carbide absorber material in the rotating drums faces inwards; During core startup, all rotating drums rotate in the same direction, causing the boron carbide absorber material to gradually face outwards until the core reaches critical power operation. As the core burns up and reactivity is lost, in order to maintain the core's critical power operation, all rotating drums continue to rotate until the boron carbide absorber material faces outwards.

[0014] The beneficial effects of this invention are: By simultaneously arranging oxide fuel rods and metal hydride fuel rods in the active region of the reactor core, a fast thermal coupling design of the neutron energy spectrum in the reactor core is achieved, thereby improving the reactivity control value of the rotating drum. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the oxide fuel rod of the present invention.

[0016] Figure 2 This is a schematic diagram of the structure of the metal hydride fuel rod of the present invention.

[0017] Figure 3 This is a schematic diagram of the rotating drum structure of the present invention.

[0018] Figure 4 This is a schematic diagram of the reactor core in Example 1, showing the uniformly dispersed arrangement of metal hydride fuel rods and oxide fuel rods.

[0019] Figure 5 This is a schematic diagram of a reactor core in Example 2, where the central active region consists of oxide fuel rods and the outer region consists of metal hydride fuel rods.

[0020] Reference numerals: 1-Oxide fuel rod core, 2-Helium, 3-Clad, 4-Lead bismuth, 5-Metal hydride fuel rod core, 6-Beryllium oxide reflective material, 7-Borne carbide absorber material, 8-Air gap, 9-Insulation shielding layer, 101-Oxide fuel rod, 102-Metal hydride fuel rod, 103-Inner coolant channel, 104-Coolant channel, 105-Outer coolant channel, 106-Beryllium oxide reflective layer, 107-Rotating drum. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] To increase the reactivity control value of the rotating drum without limiting the radial dimensions of the reactor core, this invention, based on the neutron moderation effect of metal hydride fuel and moderator, utilizes rapid thermal coupling in a rotating drum-controlled reactor to enhance the reactivity control value of the rotating drum, as well as improve the core design margin and core performance. The specific scheme is as follows: Example 1 This embodiment provides a fast thermally coupled metal hydride reactor core controlled by a rotating drum 107, such as... Figures 1-4 As shown, it should be noted that Figure 4 The illustrated colors of oxide fuel rod 101 and metal hydride fuel rod 102 are the same as those in the diagram. Figure 1 , Figure 2The colors in the diagram are irrelevant. Its core power is 10 MWt, and its lifespan is 1000 EFPD.

[0023] The reactor core active zone contains 1002 fuel rods, of which 711 are low-enriched oxide fuel rods (101) with a UO2 core enriched at 5%; and the remaining 291 are high-enriched metal hydride fuel rods (102) with a UZrH core. 1.6 The enrichment level is 20%.

[0024] It should be noted that the number of oxide fuel rods 101 and metal hydride fuel rods 102 can be set according to actual needs. That is, according to the core neutron energy spectrum softening procedure, the arrangement ratio of metal hydride fuel rods 102 and metal hydride moderators in the core can be adjusted to achieve the soft and hard adjustment of the core neutron energy spectrum.

[0025] The equivalent diameter of the active zone of the reactor core is 33 cm, the height of the active zone is 80 cm, the core power density is 144 W / cm3, the initial uranium loading at the end of the core's life is 299 kg, and the average burn-up depth at the end of the core's life is 33 GWd / tU.

[0026] The reactor core active region is composed of 711 low-enriched oxide fuel rods 101 and 291 high-enriched metal hydride fuel rods 102, uniformly mixed and arranged. Outside the active region are, in sequence, an inner coolant channel 103, a coolant channel 104, an outer coolant channel 105, a beryllium oxide reflector layer 106, and a thermal insulation shielding layer 9. Specifically, the coolant channel 104 is composed of the inner coolant channel 103 and the outer coolant channel 105; the active region is enclosed by the inner coolant channel 103; the beryllium oxide reflector layer 106 is fitted over the outer coolant channel 105; and the thermal insulation shielding layer 9 is fitted over the beryllium oxide reflector layer 106.

[0027] The coolant used in the reactor core can be different coolant fluids commonly used in fast reactors, such as lead-bismuth 4, helium-xenon, helium, and supercritical carbon dioxide.

[0028] It should also be noted that the strategy of mixing metal hydride fuel rods 102 with conventional uranium dioxide fuel rods softens the neutron energy spectrum in the reactor core, improves the zinc-plated fission reactivity rate, effectively reduces the critical mass of the reactor core, and reduces the amount of uranium loaded in the reactor core.

[0029] The reactor core also includes several rotating drums 107, which are uniformly arranged circumferentially between the beryllium oxide reflective layer 106 and the thermal insulation shielding layer 9. Air gaps 8 exist between the beryllium oxide reflective layer 106, the thermal insulation shielding layer 9, and the rotating drums 107 to facilitate control of their rotation. In this embodiment, eight rotating drums 107 are provided, with a rotation diameter of 12.5 cm. Each rotating drum 107 is a solid cylindrical structure with a circular axial cross-section. Within this circular area, a sector with a central angle of 240 degrees is the beryllium oxide reflective material 6, and the remaining sector with a central angle of 120 degrees is the boron carbide absorber material 7. The boron-10 content in the boron carbide absorber material 7 is 90%. The total reactivity value of the rotating drum 107 is 6676 pcm, meeting the requirements for shutdown depth and single-strand loading.

[0030] In this embodiment, the core radius of both oxide fuel rod 101 and metal hydride fuel rod 102 is 0.4 cm, and the inner diameter of their casing 3 is 0.41 cm and the outer diameter is 0.47 cm. The casing 3 is made of stainless steel. The center distance between all fuel rods is 1 cm, and the grid pitch-to-diameter ratio is 1.1.

[0031] In this reactor core, metal hydride fuel rods 102 or moderator rods are uniformly mixed and arranged with conventional uranium dioxide fuel rods (oxide fuel rods 101), which softens the neutron energy spectrum in the reactor core, improves the zinc fission reactivity rate, effectively reduces the critical mass of the reactor core, and effectively improves the reactivity control value of the rotating drum 107.

[0032] And under this method In this reactor core, the control method for the rotating drum 107 is as follows: When the reactor is shut down, all the boron carbide absorber material 7 of the rotating drum 107 faces inward to ensure maximum neutron absorption and keep the reactor in a deep subcritical state.

[0033] During core startup, all rotating drums 107 rotate in the same direction (clockwise or counterclockwise, but clockwise rotation is typically used for control of the drums 107), gradually turning the boron carbide absorber material 7 towards the outside of the reactor core. Simultaneously, as the drums 107 rotate, the absorber material gradually shifts from facing the core center outwards. During this process, the beryllium oxide reflector material 6 of the drums 107 gradually turns towards the core center. It can be observed that during this process, more and more neutrons are reflected by the beryllium oxide reflector material 6, while fewer and fewer neutrons are absorbed by the boron carbide absorber material 7. As the effective neutron count in the core increases, the reactivity gradually increases. When the drums 107 rotate to a specific angle, the reactor reaches criticality. At this point, the chain reaction can sustain itself, and the reactor begins to increase its power and continues to operate at the critical power level.

[0034] As the reactivity of the burnup core decreases, to maintain critical power operation, all rotating drums 107 continue to rotate and fine-tune their rotation based on their previous rotation direction to maintain the critical power level until the boron carbide absorber material 7 faces outwards. In other words, as nuclear fuel is continuously consumed, the inherent reactivity of the core decreases. To offset this loss and maintain the reactor in a critical state to ensure stable power, it is necessary to continue to enhance the core's reactivity. This is achieved by continuing to synchronously rotate all control drums to maintain stable core power. This process is dynamic; the rotating drums 107 continuously rotate dynamically to maintain stable core power. This continues until the boron carbide absorber material 7 is completely facing outwards, while the neutron reflector material is maximally oriented towards the core center. At this point, neutron absorption is minimized, and neutron reflection is maximized. The rotating drums 107 provide maximum positive reactivity contribution to the core; this state continues until the core's lifetime is exhausted. During shutdown, the rotating drums 107 must be rotated again so that the boron carbide absorber material 7 of all rotating drums 107 faces inwards.

[0035] Example 2 This embodiment also provides a fast thermally coupled metal hydride reactor core controlled by a rotating drum 107, such as Figures 1-3 as well as Figure 5 As shown, it should be noted that Figure 5 The illustrated colors of oxide fuel rod 101 and metal hydride fuel rod 102 are the same as those in the diagram. Figure 1 , Figure 2 The colors in the diagram are irrelevant. Its core power is 10 MWt, and its lifespan is 1000 EFPD.

[0036] The reactor core active zone contains 1002 fuel rods, of which 418 are low-enriched oxide fuel rods 101 with a UO2 core and an enrichment level of 6%; the other 584 are high-enriched metal hydride fuel rods 102 with a UZrH core. 1.6 The enrichment level is 23%.

[0037] It should be noted that the number of oxide fuel rods 101 and metal hydride fuel rods 102 can be set according to actual needs. That is, according to the core neutron energy spectrum softening procedure, the arrangement ratio of metal hydride fuel rods 102 and metal hydride moderators in the core can be adjusted to achieve the soft and hard adjustment of the core neutron energy spectrum.

[0038] The equivalent diameter of the active zone of the reactor core is 33 cm, the height of the active zone is 80 cm, the core power density is 144 W / cm3, the initial uranium loading at the end of the core's life is 263 kg, and the average burn-up depth at the end of the core's life is 38 GWd / tU.

[0039] Of these, 418 low-enriched oxide fuel rods 101 are concentrated in the central region of the core active zone, while another 584 high-enriched metal hydride fuel rods 102 are arranged around the periphery of the core active zone. Outside the core active zone, in sequence, are the coolant channel inner barrel 103, the coolant channel 104, the coolant channel outer barrel 105, the beryllium oxide reflector layer 106, and the thermal insulation shielding layer 9. Specifically, the coolant channel 104 is composed of the coolant channel inner barrel 103 and the coolant channel outer barrel 105; the core active zone is enclosed by the coolant channel inner barrel 103; the beryllium oxide reflector layer 106 is fitted onto the coolant channel outer barrel 105; and the thermal insulation shielding layer 9 is fitted onto the beryllium oxide reflector layer 106.

[0040] The coolant used in the reactor core can be different coolant fluids commonly used in fast reactors, such as lead-bismuth 4, helium-xenon, helium, and supercritical carbon dioxide.

[0041] It should also be noted that the arrangement strategy of having oxide fuel rods 101 concentrated in the central region of the core active area and metal hydride fuel rods 102 arranged around the periphery of the core active area can achieve hyperthermal spectrum moderation design, soften the energy spectrum in the core, improve the core fission reaction rate, and reduce the core critical mass.

[0042] The reactor core also includes several rotating drums 107, which are uniformly arranged circumferentially between the beryllium oxide reflective layer 106 and the thermal insulation shielding layer 9. Air gaps 8 exist between the beryllium oxide reflective layer 106, the thermal insulation shielding layer 9, and the rotating drums 107 to facilitate control of their rotation. In this embodiment, 12 rotating drums 107 are provided, each with a rotation diameter of 6.5 cm. Each rotating drum 107 is a solid cylindrical structure with a circular axial cross-section. Within this circular area, a sector with a central angle of 240 degrees is the beryllium oxide reflective material 6, and the remaining sector with a central angle of 120 degrees is the boron carbide absorber material 7. The boron-10 content in the boron carbide absorber material 7 is 90%. The total reactivity value of the rotating drum 107 is 7041 pcm, meeting the requirements for shutdown depth and single-strand loading.

[0043] In this embodiment, the core radius of both oxide fuel rod 101 and metal hydride fuel rod 102 is 0.4 cm, and the inner diameter of their casing 3 is 0.41 cm and the outer diameter is 0.47 cm. The casing 3 is made of stainless steel. The center distance between all fuel rods is 1 cm, and the grid pitch-to-diameter ratio is 1.1.

[0044] In this reactor core, metal hydride fuel rods 102 or moderator rods are dispersed in the outer region of the active zone of the core, so that the core is arranged in a fast thermal coupling manner. The energy spectrum inside the core is harder and the energy spectrum outside the core is softer. Under the softened neutron energy spectrum, the reactivity control value of the rotating drum 107 can be effectively improved.

[0045] Meanwhile, the core is arranged radially with fuel enrichment zones, and the core power distribution is designed to be high on the outside and low on the inside. This increases the neutron flux rate in the rotating drum 107 region, thereby increasing the value of the rotating drum 107. At the same time, the shadowing effect of the rotating drum 107 will increase the value of the rotating drum 107 at the end of the core's life. The control value of the rotating drum 107 throughout the entire life should meet the requirements.

[0046] In this reactor core, the control method for the rotating drum 107 is as follows: When the reactor is shut down, all the boron carbide absorber material 7 of the rotating drum 107 faces inward to ensure maximum neutron absorption and keep the reactor in a deep subcritical state.

[0047] During core startup, all rotating drums 107 rotate in the same direction (clockwise or counterclockwise, but clockwise rotation is typically used for control of the drums 107), gradually turning the boron carbide absorber material 7 towards the outside of the reactor core. Simultaneously, as the drums 107 rotate, the absorber material gradually shifts from facing the core center outwards. During this process, the beryllium oxide reflector material 6 of the drums 107 gradually turns towards the core center. It can be observed that during this process, more and more neutrons are reflected by the beryllium oxide reflector material 6, while fewer and fewer neutrons are absorbed by the boron carbide absorber material 7. As the effective neutron count in the core increases, the reactivity gradually increases. When the drums 107 rotate to a specific angle, the reactor reaches criticality. At this point, the chain reaction can sustain itself, and the reactor begins to increase its power and continues to operate at the critical power level.

[0048] As the reactivity of the burnup core decreases, to maintain critical power operation, all rotating drums 107 continue to rotate and fine-tune their rotation based on their previous rotation direction to maintain the critical power level until the boron carbide absorber material 7 faces outwards. In other words, as nuclear fuel is continuously consumed, the inherent reactivity of the core decreases. To offset this loss and maintain the reactor in a critical state to ensure stable power, it is necessary to continue to enhance the core's reactivity. This is achieved by continuing to synchronously rotate all control drums to maintain stable core power. This process is dynamic; the rotating drums 107 continuously rotate dynamically to maintain stable core power. This continues until the boron carbide absorber material 7 is completely facing outwards, while the neutron reflector material is maximally oriented towards the core center. At this point, neutron absorption is minimized, and neutron reflection is maximized. The rotating drums 107 provide maximum positive reactivity contribution to the core; this state continues until the core's lifetime is exhausted. During shutdown, the rotating drums 107 must be rotated again so that the boron carbide absorber material 7 of all rotating drums 107 faces inwards.

[0049] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fast thermally coupled metal hydride reactor core controlled by a rotating drum (107), characterized in that, It includes a rotating drum (107), a core active zone, a coolant flow channel (104), a beryllium oxide reflector layer (106), and a thermal insulation shielding layer (9); The coolant flow channel (104) is composed of an inner coolant flow channel barrel (103) and an outer coolant flow channel barrel (105); The core active zone is enclosed by the coolant flow channel inner barrel (103), and oxide fuel rods (101) and metal hydride fuel rods (102) are provided in the core active zone; The beryllium oxide reflective layer (106) is sleeved on the outer barrel (105) of the coolant flow channel, and the thermal insulation shielding layer (9) is sleeved on the beryllium oxide reflective layer (106); Several rotating drums (107) are arranged circumferentially between the beryllium oxide reflective layer (106) and the thermal insulation shielding layer (9).

2. The fast thermally coupled metal hydride reactor core controlled by a rotating drum (107) as described in claim 1, characterized in that, The rotating drum (107) is made of beryllium oxide reflective material (6) and boron carbide absorber material (7). The axial cross-section of the rotating drum (107) is circular. The fan-shaped area with a central angle of 240 degrees in the circular area is beryllium oxide reflective material (6), and the remaining fan-shaped area with a central angle of 120 degrees is boron carbide absorber material (7).

3. The fast thermally coupled metal hydride reactor core controlled by a rotating drum (107) as described in claim 2, characterized in that, The boron-10 content in the boron carbide absorber material (7) is 90%.

4. The fast thermally coupled metal hydride reactor core controlled by a rotating drum (107) as described in claim 1, characterized in that, Both the beryllium oxide reflective layer (106) and the thermal insulation shielding layer (9) have an air gap (8) between them and the rotating drum (107).

5. The fast thermally coupled metal hydride reactor core controlled by a rotating drum (107) as described in claim 4, characterized in that, The oxide fuel rods (101) and metal hydride fuel rods (102) are uniformly mixed and arranged in the active region of the reactor core.

6. The fast thermally coupled metal hydride reactor core controlled by a rotating drum (107) as described in claim 4, characterized in that, The oxide fuel rods (101) are concentrated in the central region of the core active area, and the metal hydride fuel rods (102) are arranged around the core active area.

7. The fast thermally coupled metal hydride reactor core controlled by a rotating drum (107) as described in claim 5, characterized in that, The number of rotating drums (107) is 8; the core of the oxide fuel rod (101) is UO2 with a fuel enrichment of 5%; the core of the metal hydride fuel rod (102) is UZrH. 1.6 The fuel enrichment level is 20%.

8. The fast thermally coupled metal hydride reactor core controlled by a rotating drum (107) as described in claim 6, characterized in that, The number of rotating drums (107) is 12; the core of the oxide fuel rod (101) is UO2 with a fuel enrichment of 6%; the core of the metal hydride fuel rod (102) is UZrH. 1.6 The fuel enrichment level is 23%.

9. The fast thermally coupled metal hydride reactor core controlled by a rotating drum (107) as described in any one of claims 5-8, characterized in that, Both the oxide fuel rod (101) and the metal hydride fuel rod (102) consist of a core and a shell (3), with the core disposed inside the shell (3) and filled with helium (2) between the core and the shell (3).

10. A rotating drum (107) control method, applied to a fast thermally coupled metal hydride reactor core controlled by a rotating drum (107) as described in any one of claims 1-9, characterized in that, include: When the reactor is shut down, the boron carbide absorber material (7) of all rotating drums (107) faces inward; During the core startup process, all rotating drums (107) rotate in the same direction to gradually turn the boron carbide absorber material (7) towards the outside of the core until the core reaches critical power operation. As the reactivity of the burnup core is lost, in order to maintain the core critical power operation, all rotating drums (107) continue to rotate until the boron carbide absorber material (7) turns towards the outside of the core.

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