CN-122000103-A - Separation device and separation method for spent fuel pellets and cladding

CN122000103ACN 122000103 ACN122000103 ACN 122000103ACN-122000103-A

Abstract

The invention relates to the technical field of spent fuel aftertreatment, in particular to a device and a method for separating spent fuel pellets from cladding. The spent fuel pellet and cladding separation device comprises a charging cavity, a vibrator, a rotary driving mechanism and an inclined driving mechanism. The charging cavity comprises a first cavity, a second cavity and a sieve plate, wherein the first cavity is connected with the second cavity through the sieve plate, the first cavity is connected with a feed inlet, an air inlet and an cladding outlet, and the second cavity is connected with a powder outlet and an exhaust port. The vibrator is connected with the charging cavity, and the vibrator is used for driving the charging cavity to vibrate. The rotary driving mechanism is connected with the charging cavity and is used for driving the charging cavity to rotate by taking the central shaft as a rotating shaft. The inclined driving mechanism is connected with the charging cavity and is used for driving the charging cavity to incline from one end to the other end of the central shaft. The device and the method not only can realize high-quality and high-efficiency separation of the spent fuel pellets and the cladding, but also can reduce the waste production in the spent fuel post-treatment process and improve the energy efficiency of the spent fuel post-treatment.

Inventors

CHEN DESHENG
WEI BINGQING
JIA HEXIANG
TAN CUNMIN
FAN FANGLI
Yao Yadu
QIN ZHI
HUANG QINGGANG
BAI JING
TIAN WEI
LIN MU

Assignees

中国科学院近代物理研究所

Dates

Publication Date: 20260508
Application Date: 20251231

Claims (10)

1. A spent fuel pellet and cladding separation device, comprising: The charging cavity comprises a first cavity, a second cavity and a sieve plate, wherein the first cavity is connected with the second cavity through the sieve plate, the first cavity is connected with a feed inlet, an air inlet and a cladding outlet, and the second cavity is connected with a powder outlet and an air outlet; the vibrator is connected with the charging cavity and is used for driving the charging cavity to vibrate; The rotary driving mechanism is connected with the charging cavity and is used for driving the charging cavity to rotate by taking a central shaft as a rotary shaft, and the central shaft is the axis of the charging cavity; and the inclined driving mechanism is connected with the charging cavity and is used for driving the charging cavity to incline from one end of the central shaft to the other end.
2. The spent fuel pellet and cladding separation device of claim 1, wherein the first cavity is at least partially inserted within the second cavity.
3. The spent fuel pellet and cladding separation device of claim 2, wherein the loading cavity is provided with a first end and a second end, the first cavity being connected to the first end, the second cavity being connected to the second end; The screen plate is arranged as the side wall of the first cavity close to the end plate, and/or the screen plate is arranged as the end plate of the first cavity.
4. The separation device for spent fuel pellets and cladding according to claim 3, wherein a plurality of sieve holes are distributed on the sieve plate, each sieve hole is uniformly distributed along the circumference of the side wall of the first cavity close to the end plate, and/or each sieve hole is distributed at the position of the end plate of the first cavity close to the outer edge.
5. The spent fuel pellet and cladding separation device of claim 3, wherein the loading chamber further comprises: The thread rib is formed on the inner wall of the first cavity and is arranged at a position close to the first end of the charging cavity; The baffle plates are connected to the inner wall of the first cavity, are arranged at the positions of the sieve plates, are uniformly arranged along the circumferential direction of the first cavity, and are arranged along the central shaft.
6. The spent fuel pellet and cladding separation device of any one of claims 1-5, wherein the rotary drive mechanism comprises: The gear disc is connected with the charging cavity; And an output shaft of the rotary driving motor is connected with the gear plate through tooth meshing.
7. The spent fuel pellet and cladding separation device of any one of claims 1-5, wherein the tilt drive mechanism comprises: a support platform supported below the loading cavity; a first driving part connected to the support platform; The second driving part is connected with the first driving part, the second driving part is provided with a connecting shaft, and the first driving part is connected with the connecting shaft in a meshed manner through a worm gear transmission mechanism so as to enable the first driving part to rotate relative to the connecting shaft; Wherein, the connecting axle perpendicular to the center pin setting of charging chamber.
8. The spent fuel pellet and cladding separation device of any one of claims 1-5, further comprising a heating and insulating mechanism comprising a thermocouple and an insulating layer, wherein the heating and insulating layer is wrapped on an outer wall of the loading cavity, and wherein the thermocouple is disposed between the heating and insulating layer and the outer wall of the loading cavity.
9. The spent fuel pellet and cladding separation device of any one of claims 1-5, further comprising: the shell receiving tank is connected to the shell outlet; a powder receiving tank connected to the powder outlet; Balance is connected with the powder receiving tank.
10. A spent fuel pellet and cladding separation method, characterized in that it is performed with the spent fuel pellet and cladding separation device according to any one of claims 1-9; the separation method of the spent fuel pellets and the cladding comprises the following steps: The tilting driving mechanism is used for driving the charging cavity to tilt towards one end of the powder outlet, and the rotating driving mechanism is used for driving the charging cavity to rotate; putting a short spent fuel section into a first cavity of the charging cavity through a feed inlet, wherein the short spent fuel section is subjected to oxidation reaction in the first cavity and disintegrates to form a cladding and powder; driving the charging cavity to vibrate by using a vibrator, wherein the powder enters a second cavity of the charging cavity through a sieve plate, and all the powder is discharged through a powder outlet; After all of the powder has been expelled, the tilt drive mechanism is used to drive the loading chamber to tilt toward the end of the enclosure outlet to cause the enclosure to exit the first chamber through the enclosure outlet.

Description

Separation device and separation method for spent fuel pellets and cladding Technical Field The invention relates to the technical field of spent fuel aftertreatment, in particular to a device and a method for separating spent fuel pellets from cladding. Background In a nuclear power plant reactor, nuclear fuel (typically ceramic pellets sintered from uranium dioxide) is sealed in cladding tubes made of a metal alloy (e.g. zirconium alloy) to form fuel rods. The irradiated nuclear fuel is called spent fuel, contains a large amount of fission products in the spent fuel, and has extremely strong radioactivity. In order to achieve closed cycle of nuclear fuel, improve uranium resource utilization and reduce radioactive waste, post-treatment of spent fuel is required. The spent fuel pellets are safely and efficiently separated from the metal cladding, and the method is one of key head-end steps in the post-treatment process. Currently, the dominant technology for separating spent fuel pellets from cladding is mechanical cutting and dissolution. The separation is typically accomplished by cutting the fuel rod into short segments with a shear and then dissolving the exposed fuel pellets with a chemical solvent (e.g., hot nitric acid) while the metallic sheath remains as an insoluble material. However, the method has a plurality of inherent defects of large secondary waste amount, high nuclear critical safety risk, difficult equipment corrosion and maintenance and the like. To overcome the above disadvantages, the prior art generally employs multiple solvent-free or dry separation methods to achieve the disintegration separation of the spent fuel pellets from the cladding. For example, the spent fuel pellets and the cladding are treated in a high temperature, oxidizing atmosphere (e.g., air, oxygen) with little oxidation of the surface of the zirconium cladding tube during the treatment process, ensuring that the overall structure of the separated cladding is complete, while uranium dioxide pellets oxidize to triuranium octoxide powder. However, the volume of the triuranium octoxide powder expands during the oxidation process, and the powder is blocked in the zirconium tube under static conditions, so that further permeation of oxygen is prevented, and the powder is prevented from being separated from the zirconium tube, and thus effective core-pack separation cannot be realized. In practice, the existing separation device generally has the problems that the oxidation rate of the inner layer of the uranium dioxide (UO 2) subjected to static oxidation is less than 60%, the stuck shell rate of the uranium dioxide (U 3O8) is more than 30%, and the separation rate of the dynamic oxidation is only about 85%, so that the separation treatment requirement that the separation rate of the spent fuel core package is more than or equal to 99% in the spent fuel post-treatment cannot be met. In addition, separation is achieved by a mechanical ejection method for low fuel consumption, but the operation amount is small, and industrial use is not possible. Disclosure of Invention The invention provides a separation device and a separation method for spent fuel pellets and cladding, which are used for solving the defects of large secondary waste amount, powder clamping shell and incomplete oxidation existing after the spent fuel is subjected to post-treatment in the prior art, not only can realize high-quality and high-efficiency separation of the spent fuel pellets and the cladding, but also can further realize separation of substances such as tritium, iodine, carbon, krypton, xenon and the like which are volatile fission products, and greatly reduces the waste production in the post-treatment process of the spent fuel. The invention provides a spent fuel pellet and cladding separation device which comprises a charging cavity, a vibrator, a rotary driving mechanism and an inclined driving mechanism, wherein the charging cavity comprises a first cavity, a second cavity and a sieve plate, the first cavity is connected with the second cavity through the sieve plate, the first cavity is connected with a feed inlet, an air inlet and a cladding outlet, the second cavity is connected with a powder outlet and an air outlet, the vibrator is connected with the charging cavity and is used for driving the charging cavity to vibrate, the rotary driving mechanism is connected with the charging cavity and is used for driving the charging cavity to rotate by taking a central shaft as a rotary shaft, the central shaft is the axis of the charging cavity, and the inclined driving mechanism is connected with the charging cavity and is used for driving the charging cavity to incline from one end of the central shaft to the other end of the central shaft. According to the separation device for the spent fuel pellets and the cladding, the first cavity is at least partially inserted into the second cavity. According to the separation device for the spent