Preparation method of hollow pellet containing boron zirconium alloy burnable poison

Abstract

The invention provides a preparation method of a hollow pellet containing boron zirconium alloy burnable poison. The method is as below: mixing boron carbide particles with size less than 5mum with a zirconium hydride-2 powder; pressing the mixture by a steel mold into a hollow pellet blank; and conducting dehydrogenation sintering and machining on the hollow pellet blank, so as to prepare a hollow pellet product containing boron zirconium alloy burnable poison. The hollow pellet containing boron zirconium alloy burnable poison prepared by the method provided by the invention has thickness less than 2mm, density higher than 95% and opening pore rate less than 2%, satisfies relevant technological requirements of pellet containing boron zirconium alloy burnable poison used in reactors; the method solves a technical problem that a powder containing a superhard material is difficult to be molded by a steel mold, and greatly improves molding precision and utilization rate of pellet containing superhard particle material; and compared with rubber molding preparation of a solid boron carbide zirconium alloy combustible poison pellet, the method reduces consumption of the raw material zirconium hydride by more than 60%.

Description

technical field

[0001] The invention belongs to a nuclear material manufacturing process, in particular to a method for preparing a boron-containing zirconium alloy burnable poison pellet. Background technique

[0002] The currently prepared boron carbide zirconium alloy burnable poisons are all solid pellets, such as: April 1963, "Effect of high boron burnups on BMI-1627 4 C and ZrB 2 dispersions in Al 2 o 3 and Zircaloy-2" introduces the use of Zr-2 powder and boron carbide powder as raw materials to prepare boron carbide zirconium alloy burnable poison solid pellets by hot extrusion. Another example: "Trans.Jap.Inst.Metals" No. 14 Vol. 6, pp. 504-510, "Hot swage fabrication of Zircaloy-2 rod containing B 4 C" introduces the preparation method of boron carbide zirconium alloy burnable poison solid pellets by hot die forging. Another example: the Chinese patent "Preparation method of boron carbide zirconium alloy burnable poison pellets" with patent number 98124660.5 ...

Examples

Embodiment 1

[0024] Step 1 Mixing: Mix the weighed zirconium hydride-2 powder and boron carbide powder, and then put the powder into a mixer for mixing; wherein the particle size of boron carbide is <5 μm, the mass fraction is 0.5%, and the balance It is zirconium hydride-2 powder; the mixing time is 30min;

[0025] Step 2 Steel mold pressing molding: put the mixed zirconium hydride-2 and boron carbide powder into a steel mold with a core rod and press it into a hollow pellet blank, and press the powder into a hollow pellet blank The pressure is 500MPa;

[0026] Step 3 Dehydrogenation sintering: put the pressed zirconium hydride-2 and boron carbide hollow pellet body into a high-vacuum sintering furnace for dehydrogenation sintering, heat up when the vacuum degree is less than 0.1Pa, keep warm at 800°C for dehydrogenation, Until the vacuum degree of the furnace drops below 0.1Pa, the temperature is raised to 1300°C and kept for 60 minutes. After the heat preservation is completed, the hol...

Embodiment 2

[0029] Step 1 Mixing: Mix the weighed zirconium hydride-2 powder and boron carbide powder, and then put the powder into a mixer for mixing; wherein the particle size of boron carbide is <5 μm, and the mass fraction is 1%, and the remaining The amount is zirconium hydride-2 powder; the mixing time is 60min;

[0030] Step 2 Steel mold compression molding: put the mixed zirconium hydride-2 and boron carbide powder into a steel mold with a core rod and press it into a hollow pellet body, and press the mixed powder of zirconium hydride-2 and boron carbide The forming pressure of the hollow pellet body is 400MPa;

[0031] Step 3 Dehydrogenation sintering: put the pressed zirconium hydride-2 and boron carbide hollow pellet body into a high vacuum sintering furnace for dehydrogenation sintering, heat up when the vacuum degree is less than 0.1Pa, keep warm at 850°C for dehydrogenation, Until the vacuum degree of the furnace drops below 0.1Pa, the temperature is raised to 1250°C and ke...

Embodiment 3

[0034] Step 1 Mixing: Mix the weighed zirconium hydride-2 powder and boron carbide powder, and then put the powder into a mixer for mixing; wherein the particle size of boron carbide is <5 μm, and the mass fraction is 1%, and the remaining The amount is zirconium hydride-2 powder; the mixing time is 90min;

[0035] Step 2 Compression molding: Put the mixed zirconium hydride-2 and boron carbide powder into a steel mold with a core rod and press it into a hollow pellet body, and press zirconium hydride-2 and boron carbide powder into a hollow pellet The molding pressure of the green body is 200MPa;

[0036] Step 3 Dehydrogenation sintering: put the pressed zirconium hydride-2 and boron carbide hollow pellet body into a high-vacuum sintering furnace for dehydrogenation sintering, heat up when the vacuum degree is less than 0.1Pa, and keep warm at 850°C until the furnace The vacuum degree drops below 0.1Pa, then the temperature is raised to 1300°C, and the heat preservation is ca...

technical field

[0001] The invention belongs to a nuclear material manufacturing process, in particular to a method for preparing a boron-containing zirconium alloy burnable poison pellet. Background technique

[0002] The currently prepared boron carbide zirconium alloy burnable poisons are all solid pellets, such as: April 1963, "Effect of high boron burnups on BMI-1627 4 C and ZrB 2 dispersions in Al 2 o 3 and Zircaloy-2" introduces the use of Zr-2 powder and boron carbide powder as raw materials to prepare boron carbide zirconium alloy burnable poison solid pellets by hot extrusion. Another example: "Trans.Jap.Inst.Metals" No. 14 Vol. 6, pp. 504-510, "Hot swage fabrication of Zircaloy-2 rod containing B 4 C" introduces the preparation method of boron carbide zirconium alloy burnable poison solid pellets by hot die forging. Another example: the Chinese patent "Preparation method of boron carbide zirconium alloy burnable poison pellets" with patent number 98124660.5 ...

Examples

Embodiment 1

[0024] Step 1 Mixing: Mix the weighed zirconium hydride-2 powder and boron carbide powder, and then put the powder into a mixer for mixing; wherein the particle size of boron carbide is <5 μm, the mass fraction is 0.5%, and the balance It is zirconium hydride-2 powder; the mixing time is 30min;

[0025] Step 2 Steel mold pressing molding: put the mixed zirconium hydride-2 and boron carbide powder into a steel mold with a core rod and press it into a hollow pellet blank, and press the powder into a hollow pellet blank The pressure is 500MPa;

[0026] Step 3 Dehydrogenation sintering: put the pressed zirconium hydride-2 and boron carbide hollow pellet body into a high-vacuum sintering furnace for dehydrogenation sintering, heat up when the vacuum degree is less than 0.1Pa, keep warm at 800°C for dehydrogenation, Until the vacuum degree of the furnace drops below 0.1Pa, the temperature is raised to 1300°C and kept for 60 minutes. After the heat preservation is completed, the hol...

Embodiment 2

[0029] Step 1 Mixing: Mix the weighed zirconium hydride-2 powder and boron carbide powder, and then put the powder into a mixer for mixing; wherein the particle size of boron carbide is <5 μm, and the mass fraction is 1%, and the remaining The amount is zirconium hydride-2 powder; the mixing time is 60min;

[0030] Step 2 Steel mold compression molding: put the mixed zirconium hydride-2 and boron carbide powder into a steel mold with a core rod and press it into a hollow pellet body, and press the mixed powder of zirconium hydride-2 and boron carbide The forming pressure of the hollow pellet body is 400MPa;

[0031] Step 3 Dehydrogenation sintering: put the pressed zirconium hydride-2 and boron carbide hollow pellet body into a high vacuum sintering furnace for dehydrogenation sintering, heat up when the vacuum degree is less than 0.1Pa, keep warm at 850°C for dehydrogenation, Until the vacuum degree of the furnace drops below 0.1Pa, the temperature is raised to 1250°C and ke...

Embodiment 3

[0034] Step 1 Mixing: Mix the weighed zirconium hydride-2 powder and boron carbide powder, and then put the powder into a mixer for mixing; wherein the particle size of boron carbide is <5 μm, and the mass fraction is 1%, and the remaining The amount is zirconium hydride-2 powder; the mixing time is 90min;

[0035] Step 2 Compression molding: Put the mixed zirconium hydride-2 and boron carbide powder into a steel mold with a core rod and press it into a hollow pellet body, and press zirconium hydride-2 and boron carbide powder into a hollow pellet The molding pressure of the green body is 200MPa;

[0036] Step 3 Dehydrogenation sintering: put the pressed zirconium hydride-2 and boron carbide hollow pellet body into a high-vacuum sintering furnace for dehydrogenation sintering, heat up when the vacuum degree is less than 0.1Pa, and keep warm at 850°C until the furnace The vacuum degree drops below 0.1Pa, then the temperature is raised to 1300°C, and the heat preservation is ca...