Sr-90 isotope heat source sealing box and packaging method thereof

Abstract

The invention relates to an Sr-90 isotope heat source sealing box and a packaging method thereof, and the sealing box comprises a source box tank body which is used for placing an Sr-90 isotope heat source core body and is a thick-wall open barrel-shaped body, the outer edge of the top of the opening of the source box tank body is recessed inwards, and a first thread is arranged at the recessed part; the source box upper cover is matched with the source box tank body to seal the heat source core body, the source box upper cover is a barrel-shaped body with an opening, a second thread is arranged on the inner wall of the opening, a gasket is arranged at the bottom of the opening, and the source box upper cover and the source box tank body are in threaded connection through the second thread and the first thread to extrude the gasket. And the source box upper cover is connected with the opening of the source box tank body in a welding manner. Compared with the prior art, aiming at a low-power heat source, the heat transfer performance and the safety of the heat source and the operability in the preparation process are comprehensively considered, and the method has the characteristics of good heat conductivity, good safety, simple sealing process and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of isotope heat sources, and in particular relates to an Sr-90 isotope heat source sealing box and a packaging method thereof. Background Art

[0002] Thermoelectric strontium (Sr)-90 isotope power source is a device that converts decay heat into electrical energy. It has the characteristics of maintenance-free, high stability, ultra-long life, and strong environmental adaptability. It is widely used in navigation lighthouses, offshore buoys, climate monitoring, underwater communication cable switching and other devices. The Sr-90 radioactive heat source is the core component of the thermoelectric isotope power source, which is used to provide thermal energy. Safety performance and heat transfer performance are two important indicators. The Sr-90 heat source has very high radioactivity. Its sealing design and packaging process are related to the safety performance of the entire power source. It requires multiple layers of protection and strict sealing. At the same time, the high radioactivity causes the preparation of the heat source to be prepared in a hot room or work box, which has a small space and is extremely inconvenient to operate. If the sealing process of the heat source is too complicated, it will further increase the difficulty of heat source development. In addition, it is crucial for low-power Sr-90 heat sources to have high thermal conductivity. The more sealing layers, the more air gaps, the greater the thermal resistance, and the lower the surface temperature of the heat source, thereby reducing the overall conversion efficiency of the battery.

[0003] According to literature reports, in the design of Sr-90 isotope heat source, double-layer cladding is usually used to achieve the effect of double-layer sealing. The inner layer is 316 stainless steel, mainly considering the good compatibility of 316 alloy with strontium titanate; the outer cladding is Inconel 625 or other nickel-based alloys, mainly considering its good high temperature resistance. The inner and outer claddings are both welded and sealed (TIG welding or electron beam welding), and there is a certain gap between the two claddings to hinder heat transfer. The heat source preparation method mainly includes: loading strontium titanate core blocks into the inner cladding, welding and sealing the inner cladding, decontaminating the surface of the inner cladding, loading the inner cladding into the outer cladding, welding and sealing the outer cladding, and decontaminating the outer cladding. The existing heat source design is mainly aimed at high-power heat sources with very high temperatures (generally above 200°C), which can ensure the safety performance of the heat source at high temperatures. However, for low-power heat sources, the operating temperature is relatively low, and there is no need to consider the impact of high temperature on the mechanical properties of the cladding and the compatibility of the cladding with the strontium titanate heat source at high temperatures. However, the existing double-shell heat source design increases thermal resistance, increases the time it takes for the power supply device to reach a stable output, and reduces the energy conversion efficiency of the power supply device. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide an Sr-90 isotope heat source sealing box and its packaging method. For low-power heat sources, the thermal utilization rate, safety issues and operability of the heat source are comprehensively considered, and the sealing process is simple, the thermal conductivity is high, and the safety is high.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] In one aspect, the present invention provides a Sr-90 isotope heat source sealed box, comprising:

[0007] The source box tank body for placing the Sr-90 isotope heat source core is a barrel-shaped body with a thick wall and an opening, the outer edge of the top of the opening is concave inwards, and a first thread is provided at the concave part;

[0008] and a source box upper cover that cooperates with the source box tank body to seal the heat source core, which is a barrel-shaped body with an open lower end, and the inner wall of the opening is provided with a second thread that cooperates with the first thread to be tightened, and the source box upper cover is welded to the opening of the source box tank body;

[0009] And a gasket is arranged on the top of the source box upper cover and is squeezed by the source box tank body and the source box upper cover.

[0010] Furthermore, the source box tank is made of metal material, including stainless steel, nickel-based alloy, and copper alloy.

[0011] Furthermore, the source box upper cover is made of metal material, including stainless steel, nickel-based alloy, and copper alloy.

[0012] Furthermore, the gasket is made of metal material, including silver, oxygen-free copper, and polytetrafluoroethylene.

[0013] Furthermore, the heat source core comprises strontium titanate powder, strontium oxide powder, strontium titanate block, strontium oxide block, and has a power of 1 to 10W.

[0014] Furthermore, the top inner wall of the source box upper cover is provided with a back-cut groove which is recessed on both sides and accommodates a partial area of ​​the gasket, and the back-cut groove is connected to the root of the second thread.

[0015] Furthermore, the outer wall of the washer is provided with a third thread which cooperates with the second thread and is screwed into the tool retreat groove. After being screwed in, a certain gap is formed between the washer and the tool retreat groove.

[0016] Furthermore, a first extrusion piece is provided at the top of the opening of the source box tank body, the height of which exceeds the bottom height of the backing groove and is used to resist the gasket.

[0017] Furthermore, a groove is provided on the inner side of the top of the source box upper cover, and the intersection of the groove and the knife retreat groove forms a second extrusion piece that presses against the gasket.

[0018] Furthermore, the second extrusion component is located at an outer side of the first extrusion component.

[0019] Furthermore, the first extrusion member is in a shape of a cone, a cylinder, a hemisphere or an irregular convex shape.

[0020] Furthermore, a first guide groove recessed inwardly is provided at the top of the first thread of the source box tank body;

[0021] The bottom of the second thread of the source box upper cover is provided with a second guide groove which is recessed inwards and matches with the first guide groove.

[0022] In another aspect, the present invention further provides a method for packaging an Sr-90 isotope heat source, which is packaged using the above-mentioned sealing box. The packaging method comprises the following steps:

[0023] Installing the heat source core into the source box tank;

[0024] Screw the gasket into the backing groove of the upper cover of the source box;

[0025] The source box upper cover is threadedly connected and tightened with the source box tank body through the second thread and the first thread, and the gasket is squeezed until it is squeezed and deformed to form a primary seal;

[0026] The source box upper cover is welded to the opening of the source box tank body to form a secondary seal.

[0027] Furthermore, the source box upper cover and the source box tank body are tightened with a capping machine according to a certain torque.

[0028] Furthermore, the source box upper cover and the source box tank body are sealed by laser welding. The heat-affected zone of laser welding is small and will not affect the sealing performance of the gasket.

[0029] Furthermore, the surface of the sealed box is decontaminated.

[0030] Furthermore, the specific process of the decontamination treatment is: wiping with a rag dipped in a solution such as alcohol.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) The present invention forms a primary seal by squeezing the gasket until it is squeezed and deformed when the source box upper cover is threadedly connected to the source box tank body; and a secondary seal is formed by welding the source box upper cover to the opening of the source box tank body. The present invention adopts a single-layer heat source shell but achieves a double-layer seal. Under the condition of ensuring the sealing of the heat source, one layer of shell and the air between the two layers of shell are eliminated. Compared with metal heat conduction, the thermal conductivity of air is very low. The present invention significantly reduces thermal resistance and can increase the hot end temperature of a temperature difference thermoelectric power supply. In particular, for low-power power supplies, it can significantly improve the overall performance of the battery and reduce the leakage of radioactive substances.

[0033] (2) The present invention threadably connects the source box upper cover with the source box tank body through the second thread and the first thread, so that the source box upper cover and the source box tank body can be effectively screwed together.

[0034] (3) The present invention provides a back-cut groove in the source box upper cover, and the gasket is screwed into the back-cut groove through the third thread, so that the gasket can be firmly fixed in the source box upper cover to prevent it from falling off. After being screwed in, there is a certain gap between the gasket and the back-cut groove, so that the gasket can be squeezed and deformed when being acted upon by the first extrusion member and the second extrusion member, thereby achieving a sealing effect.

[0035] (4) The present invention provides a first extrusion member for resisting the gasket at the top of the opening of the source box tank body, and provides a groove at the top of the source box upper cover, so that a second extrusion member resisting the gasket is formed at the intersection of the groove and the backing groove, and the second extrusion member is arranged at a position slightly outside the first extrusion member, so that the first extrusion member and the second extrusion member are not located on the same vertical line. When the source box upper cover is screwed onto the source box tank body, the first extrusion member continuously squeezes the gasket and applies upward pressure to it. Since the second extrusion member is located slightly outside the first extrusion member, the gasket is subjected to the downward pressure of the second extrusion member. Under the action of the staggered upward and downward forces, the gasket is firmly installed between the source box upper cover and the source box tank body, so that a seal is formed.

[0036] (5) In the present invention, there are no threads at the bottom end of the source box cover and the top end of the source box tank body. The top of the first thread of the source box tank body is provided with a first guide groove that is recessed inwards; the bottom of the second thread of the source box cover is provided with a second guide groove that is recessed inwards and cooperates with the first guide groove. When the first guide groove and the second guide groove are in contact, they play a role of positioning and guiding, and when the manipulator is operated, the first thread of the source box cover and the second thread of the source box tank body can be screwed together more quickly.

[0037] (6) The present invention uses welding to seal the source box cover and the source box tank body to form a secondary seal, and the heat affected zone of laser welding is small and will not affect the sealing of the gasket.

[0038] (7) The packaging process of the present invention includes filling the heat source core, screwing the gasket into the source box cover, threading the source box cover and the source box tank body, and welding the source box cover and the source box tank body. The sealed box is easy to assemble. Using the sealed box for packaging can shorten the process flow, reduce the exposure dose of operators, and ensure the safety performance of the heat source. The present invention is suitable for low-power Sr-90 isotope heat sources, the surface temperature of the heat source is not high, and the high-temperature mechanical properties and antioxidant properties of the material are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a cross-sectional view of the sealing box shown in Example 1;

[0040] Figure 2 is a cross-sectional view of the source box tank body shown in Example 1;

[0041] Figure 3 is a cross-sectional view of the upper cover of the source box shown in Example 1;

[0042] Figure 4 This is a cross-sectional view of the gasket shown in Example 1.

[0043] Description of the markings in the figure:

[0044] 1-heat source core;

[0045] 2-source box body, 21-first thread, 22-first extrusion piece, 23-first guide groove;

[0046] 3-source box upper cover, 31-second thread, 32-knife withdrawal groove, 33-groove, 34-second extrusion piece, 35-second guide groove.

[0047] 4- Washer. DETAILED DESCRIPTION

[0048] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments. In the following embodiments or embodiments, if there is no special description of the functional components or structures, it means that they are all conventional components or conventional structures used in the art to achieve the corresponding functions.

[0049] It should be noted that in the description of the present invention, the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] A Sr-90 isotope heat source sealed box, comprising:

[0052] The source box tank body 2 for placing the Sr-90 isotope heat source core body 1 is a barrel-shaped body with a thick wall and an opening, the outer edge of the top of the opening is concave inwards, and a first thread 21 is provided at the concave part;

[0053] and a source box upper cover 3 which cooperates with the source box tank body 2 to seal the heat source core 1, which is a barrel-shaped body with an opening at the lower end, and the inner wall of the opening is provided with a second thread 31 which cooperates with the first thread 21 to be tightened, and the source box upper cover 3 is welded to the opening of the source box tank body 2;

[0054] And a gasket 4 is arranged on the top of the source box upper cover 3 and is squeezed by the source box tank body 2 and the source box upper cover 3.

[0055] As one of the preferred implementations, the source box can body 2 is made of metal material, including stainless steel, nickel-based alloy, and copper alloy.

[0056] As one of the preferred implementations, the source box upper cover 3 is made of metal material, including stainless steel, nickel-based alloy, and copper alloy.

[0057] As one of the preferred implementations, the gasket 4 is made of metal material, including silver, oxygen-free copper, and polytetrafluoroethylene.

[0058] As one of the preferred implementations, the heat source core 1 includes strontium titanate powder, strontium oxide powder, strontium titanate block, strontium oxide block, and has a power of 1 to 10W.

[0059] As one of the preferred implementations, the top inner wall of the source box upper cover 3 is provided with a backing groove 32 which is recessed on both sides and accommodates a partial area of ​​the gasket 4 , and the backing groove 32 is connected to the root of the second thread 31 .

[0060] As one of the preferred embodiments, the outer wall of the washer 4 is provided with a third thread that cooperates with the second thread 31 and is screwed into the back cutter groove 32 . After being screwed in, a certain gap is formed between the washer 4 and the back cutter groove 32 .

[0061] As one of the preferred implementations, the top of the opening of the source box tank body 2 is provided with a first extrusion piece 22 whose height exceeds the bottom height of the backing groove 32 and is used to resist the gasket 4 .

[0062] As one of the preferred implementations, a groove 33 is provided on the inner side of the top of the source box upper cover 3 , and the intersection of the groove 33 and the knife-back groove 32 forms a second extrusion piece 34 that presses against the gasket 4 .

[0063] As one of the preferred implementations, the second extrusion member 34 is located on the outside of the first extrusion member 22 .

[0064] As one of the preferred implementations, the first extrusion member 22 is in a shape of a cone, a cylinder, a hemisphere or an irregular convex shape.

[0065] As one of the preferred embodiments, the top of the first thread 21 of the source box tank body 2 is provided with a first guide groove 23 recessed inwardly;

[0066] The bottom of the second thread 31 of the source box upper cover 3 is provided with a second guide groove 35 which is recessed inwards and matches with the first guide groove 23 .

[0067] A method for packaging an Sr-90 isotope heat source, using the above-mentioned sealing box for packaging, the packaging method comprises the following steps:

[0068] The heat source core 1 is placed into the source box tank 2;

[0069] Screw the gasket 4 into the backing groove 32 of the source box upper cover 3;

[0070] The source box upper cover 3 is threadedly connected and tightened with the source box tank body 2 through the second thread 31 and the first thread 21, and the gasket 4 is squeezed until it is squeezed and deformed to form a primary seal;

[0071] The source box upper cover 3 is welded to the opening of the source box tank body 2 to form a secondary seal.

[0072] As one of the preferred implementations, the source box upper cover 3 and the source box tank body 2 are tightened with a capping machine according to a certain torque.

[0073] As one of the preferred implementations, the source box upper cover 3 and the source box tank body 2 are welded and sealed by laser welding. The heat-affected zone of laser welding is small and will not affect the sealing performance of the gasket.

[0074] As one of the preferred implementations, the surface of the sealed box is subjected to a decontamination treatment after sealing.

[0075] As one of the preferred implementations, the specific process of the decontamination treatment is: wiping with a rag dipped in alcohol.

[0076] Example 1

[0077] A sealed box for Sr-90 isotope heat source, such as Figures 1 to 4 As shown, including:

[0078] The source box tank body 2 for placing the Sr-90 isotope heat source core body 1 is a barrel-shaped body with a thick wall and an opening, the outer edge of the top of the opening is concave inwards, and a first thread 21 is provided at the concave part;

[0079] and a source box upper cover 3 which cooperates with the source box tank body 2 to seal the heat source core 1, which is a barrel-shaped body with an opening at the lower end, and the inner wall of the opening is provided with a second thread 31 which cooperates with the first thread 21 to be tightened, and the source box upper cover 3 is welded to the opening of the source box tank body 2;

[0080] And a gasket 4 is arranged on the top of the source box upper cover 3 and is squeezed by the source box tank body 2 and the source box upper cover 3.

[0081] In this embodiment, the source box tank body 2 is made of metal, such as 316L stainless steel.

[0082] In this embodiment, the source box upper cover 3 is made of metal, such as 316L stainless steel.

[0083] In this embodiment, the gasket 4 is made of metal, such as silver.

[0084] In this embodiment, the heat source core 1 is a strontium titanate block with a thermal power of 3W.

[0085] In this embodiment, the top inner wall of the source box upper cover 3 is provided with a backing groove 32 which is recessed on both sides and accommodates a partial area of ​​the gasket 4 , and the backing groove 32 is connected to the root of the second thread 31 .

[0086] In this embodiment, the outer wall of the gasket 4 is provided with a third thread that cooperates with the second thread 31 and is screwed into the backing groove 32 .

[0087] In this embodiment, the top of the opening of the source box tank body 2 is provided with a first extrusion piece 22 , which has a height exceeding the bottom height of the backing groove 32 and is used to resist the gasket 4 .

[0088] In this embodiment, a groove 33 is provided on the inner side of the top of the source box upper cover 3 , and the intersection of the groove 33 and the knife-back groove 32 forms a second extrusion member 34 that presses against the gasket 4 .

[0089] In this embodiment, the second extrusion member 34 is located at an outer side of the first extrusion member 22 .

[0090] In this embodiment, the first extrusion member 22 is in the shape of a cylinder.

[0091] In this embodiment, a first guide groove 23 recessed inward is provided at the top of the first thread 21 of the source box tank body 2;

[0092] The bottom of the second thread 31 of the source box upper cover 3 is provided with a second guide groove 35 which is recessed inwards and matches with the first guide groove 23 .

[0093] A method for packaging an Sr-90 isotope heat source, using the above-mentioned sealing box for packaging, the packaging method comprises the following steps:

[0094] The heat source core 1 is placed into the source box tank 2;

[0095] Screw the gasket 4 into the backing groove 32 of the source box upper cover 3 through the third thread;

[0096] The source box upper cover 3 is threadedly connected and tightened with the source box tank body 2 through the second thread 31 and the first thread 21, and the gasket 4 is squeezed until it is squeezed and deformed to form a primary seal;

[0097] The source box upper cover 3 is welded to the opening of the source box tank body 2 to form a secondary seal.

[0098] In this embodiment, the source box upper cover 3 and the source box tank body 2 are tightened with a capping machine according to a certain torque.

[0099] In this embodiment, the source box upper cover 3 and the source box tank body 2 are sealed by laser welding. The heat-affected zone of laser welding is small and will not affect the sealing performance of the gasket.

[0100] In this embodiment, the surface of the sealed box is decontaminated, and the specific process of the decontamination treatment is: wiping with a rag dipped in alcohol.

[0101] In summary, the Sr-90 isotope heat source sealed box of the present invention includes a source box upper cover 3, a gasket 4, and a source box tank body 2. "Double sealing" means a sealing gasket 4 + welding seal, which can reduce the leakage of radioactive substances. The heat source core 1 is placed in the source box tank body 2. Since there is only one layer of cladding, it is a "single source box", which can simplify the assembly process and reduce the exposure dose of operators. The packaging process includes: filling the heat source core 1, screwing the gasket 4 into the source box upper cover 3, threading the source box upper cover 3 and the source box tank body 2, welding the source box upper cover 3 and the source box tank body 2, and decontaminating the surface of the heat source core 1. The present invention is suitable for low-power Sr-90 isotope heat sources, the surface temperature of the heat source is not high, and has good high-temperature mechanical properties and antioxidant properties of the material.

[0102] Although the present invention has been described in detail above by means of general description, specific implementation methods and tests, it is obvious to those skilled in the art that some modifications or improvements may be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A Sr-90 isotope heat source sealed box, characterized in that: include: A source box tank (2) for placing the Sr-90 isotope heat source core (1) is a thick-walled, open barrel-shaped body, the outer edge of the top of the opening is concave inwards, and a first thread (21) is provided at the concave portion; A source box upper cover (3) cooperates with the source box tank body (2) to seal the heat source core (1), which is a barrel-shaped body with an opening at the lower end, and the inner wall of the opening is provided with a second thread (31) that cooperates with the first thread (21) to be tightened, and the source box upper cover (3) is welded to the opening of the source box tank body (2); And a gasket (4) which is arranged on the top of the source box upper cover (3) and is pressed by the source box tank (2) and the source box upper cover (3).

2. The Sr-90 isotope heat source sealed box according to claim 1, characterized in that: The source box tank (2) is made of metal, including stainless steel, nickel-based alloy, and copper alloy; The source box upper cover (3) is made of metal material, including stainless steel, nickel-based alloy, and copper alloy.

3. The Sr-90 isotope heat source sealed box according to claim 1, characterized in that: The gasket (4) is made of metal material, including silver, oxygen-free copper, and polytetrafluoroethylene.

4. The Sr-90 isotope heat source sealed box according to claim 1, characterized in that: The heat source core (1) comprises strontium titanate powder, strontium oxide powder, strontium titanate block and strontium oxide block, and has a thermal power of 1 to 10W.

5. The Sr-90 isotope heat source sealed box according to claim 1, characterized in that: The top inner wall of the source box upper cover (3) is provided with a backing groove (32) which is recessed on both sides and accommodates a partial area of ​​the gasket (4), and the backing groove (32) is connected to the root of the second thread (31).

6. The Sr-90 isotope heat source sealed box according to claim 5, characterized in that: The outer wall of the washer (4) is provided with a third thread which cooperates with the second thread (31) and is screwed into the tool withdrawal groove (32).

7. The Sr-90 isotope heat source sealed box according to claim 5, characterized in that: The top of the opening of the source box tank (2) is provided with a first extrusion piece (22) whose height exceeds the bottom height of the backing groove (32) and is used to resist the gasket (4).

8. The Sr-90 isotope heat source sealed box according to claim 7, characterized in that: A groove (33) is provided on the inner side of the top of the source box upper cover (3), and the intersection of the groove (33) and the knife retreat groove (32) forms a second extrusion piece (34) that abuts against the gasket (4); The second extrusion piece (34) is located on the outside of the first extrusion piece (22).

9. The Sr-90 isotope heat source sealed box according to claim 1, characterized in that: The top of the first thread (21) of the source box tank body (2) is provided with a first guide groove (23) recessed inwards; The bottom of the second thread (31) of the source box upper cover (3) is provided with a second guide groove (35) which is recessed inwards and matches with the first guide groove (23).

10. A method for packaging an Sr-90 isotope heat source, using the sealing box according to any one of claims 1 to 9 for packaging, characterized in that: The packaging method comprises the following steps: The heat source core (1) is placed in the source box tank (2); Screw the gasket (4) into the knife-back groove (32) of the source box upper cover (3); The source box upper cover (3) is threadedly connected to the source box tank body (2) via the second thread (31) and the first thread (21), and the gasket (4) is squeezed until it is deformed to form a primary seal; The source box upper cover (3) is welded to the opening of the source box tank body (2) to form a secondary seal.

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