CN-122000100-A - Device and method for measuring aerosol release share and particle size distribution under lead bismuth fuel breakage

CN122000100ACN 122000100 ACN122000100 ACN 122000100ACN-122000100-A

Abstract

The invention discloses a device and a method for measuring the release share and particle size distribution of aerosol under the breakage of lead-bismuth fuel, wherein the device comprises a high-pressure gas tank, an aerosol weighing device, a simulated fuel rod, a break closure device, a collecting device, a wet particle size analyzer, a pipeline valve and a measuring instrument, wherein the high-pressure gas tank is used for providing gas required by the whole device, the aerosol weighing device is used for weighing aerosol powder used in an initial state in the fuel rod, the simulated fuel rod is designed according to the size and the structure of a real lead-bismuth stack fuel rod and is used for simultaneously containing high-pressure gas and aerosol and constructing cladding breaks with different shapes and sizes, the break closure device is used for closing the closed environment inside the break structure fuel rod, the collecting device is used as a containing place of the aerosol after being released by the fuel rod and is convenient for subsequent sampling and measurement, and the wet particle size analyzer is used for measuring the particle size distribution of aerosol particles. The device can finish the measurement of the release share and the particle size distribution of the aerosol in the gap between the pellet and the cladding of the fuel rod through the crack of the cladding, and can be used for researching the release characteristics of the aerosol under different fission gas pressures, different crack sizes and different shapes.

Inventors

ZHANG JING
XIAO CONGYU
YANG GUORUI

Assignees

西安交通大学

Dates

Publication Date: 20260508
Application Date: 20260128

Claims (9)

1. The device for measuring the release share and the particle size distribution of the aerosol under the damage of the lead-bismuth fuel is characterized by comprising a high-pressure gas tank (1), an aerosol weighing device (2), a simulated fuel rod (3), a break closing device (4), a collecting device (5), a wet particle size analyzer (6), a pipeline valve and a flow pressure measuring instrument; The high-pressure gas tank (1) is used for providing gas required by the whole device and is connected with an upper port of the simulated fuel rod (3) through a ventilation pipeline with good air tightness; The aerosol weighing device (2) is used for weighing the used aerosol powder, so that the aerosol with specified quality is provided for the simulated fuel rod (3), and the aerosol is injected through the upper port of the simulated fuel rod (3), so that the residue and loss of a pipeline are reduced; The simulated fuel rod (3) is used for containing high-pressure aerosol and constructing break openings with different shapes and sizes on a fuel rod cladding, and according to the size and structural design of a real lead bismuth stack fuel rod, front-end gas enters the simulated fuel rod through the high-pressure gas tank (1), and the break opening closing device (4) is arranged on the fuel rod cladding break opening and used as a gas outlet; The breach sealing device (4) has the function of sealing the breach of the cladding of the fuel rod, can construct a sealed fuel rod inner space to bear high-pressure gas, is arranged on the simulated fuel rod (3), is used as a gas outlet when being opened, and is connected with the collecting device (5) at the rear end; The collecting device (5) is used as a containing place of the aerosol released by the fuel rod, so that the subsequent sampling and measurement are facilitated, the position is arranged at the rearmost end of the gas flow path, and the released aerosol powder is subsequently collected from the collecting device and used for measuring the particle size distribution by the wet particle size analyzer (6); the wet particle size analyzer (6) is used for measuring the particle size distribution of aerosol particles of the sample gas, and collecting the measured aerosol from the collecting device (5).
2. The device according to claim 1, characterized in that the gas in the high pressure gas tank (1) is helium and the aerosol powder is silicon dioxide powder.
3. The device according to claim 1, characterized in that the high pressure gas tank (1) consists of a plurality of gas tanks for supplying a sufficient amount of gas to the device, which high pressure gas tank is connected to the aerosol injection section of the dummy fuel rod (3) by means of a pressure regulating valve for regulating the upper end pressure of the aerosol injection section.
4. The device according to claim 1, characterized in that the aerosol weighing device (2) body is constituted by a metering balance that weighs the aerosol powder and ensures that a given mass of aerosol is provided to the simulated fuel rod.
5. The device according to claim 1, characterized in that the simulated fuel rod (3) comprises an upper end plug (3-1), a fuel rod cladding (3-2), an inner pellet (3-3), a lower end plug (3-4) and a spud (3-5), the upper end plug (3-1), the lower end plug (3-4) and the fuel rod cladding (3-2) being integrated into the fuel rod by means of a threaded connection, the fuel rod cladding (3-2) being connected to the inner pellet (3-3) by means of the spud (3-5), the lower end plug (3-4) comprising a support rod (3-8) for connecting the inner pellet (3-3) for providing support and centering, the simulated fuel rod (3) being designed with respect to the actual lead bismuth fast reactor fuel rod dimensions in each part size, while at the fuel rod cladding (3-2) a pressure gauge (3-6) is placed for measuring the simulated fuel rod inner gas pressure, and in that a break (3-7) is designed in the fuel rod cladding (3-2) for releasing the high pressure gas.
6. The device according to claim 1, wherein the breach closing means (4) comprises a breach platform (4-1), a rupture disc (4-2) and a compression flange (4-3), the internal structure of the breach platform (4-1) and the fuel rod cladding (3-2) are consistent in shape and smooth enough to ensure that the fuel rod cladding can be attached to ensure the tightness thereof, the breach is closed by installing the rupture disc (4-2) and the compression flange (4-3) at the breach while maintaining the balance of the stress of the fuel rod, and the breach is opened during the experiment when the internal pressure of the simulated fuel rod reaches the bursting pressure of the rupture disc (4-2) and aerosol particles are released outwards.
7. The device according to claim 1, characterized in that the collecting means (5) serve as an aerosol holding place for the release from the simulated fuel rod and facilitate sampling measurements, the fuel rod cladding (3-2) being connected by means of a breach closure means (4).
8. The device according to claim 1, characterized in that the wet particle size analyzer (6) is used for measuring a metering instrument for collecting the particle size distribution, particle shape distribution and counting of the released aerosol particles or droplets in the collecting device (5), and the metering instrument is used for shooting an image of the aerosol particles by a high-resolution digital industrial camera and a backlight system and analyzing morphological parameters.
9. A method of using the device of any one of claims 1-8, comprising the steps of: The method comprises the steps of assembling a simulated fuel rod, namely fixing a measuring channel of a pressure gauge (3-6) with a designated position of the simulated fuel rod, installing an inner core block (3-3) of the simulated fuel rod in alignment with a positioning pile (3-5), shaking the simulated fuel rod (3) after the assembling is finished to check whether the assembling is firm, selecting a rupture disc (4-2) which is blasted under the expected bursting pressure according to working condition setting, clamping the rupture disc (4-2) between a rupture platform (4-1) and a compression flange (4-3), and finally fixing the simulated fuel rod (3) at the designated position to prepare for starting an experiment; The aerosol is injected, aerosol particles which are calculated in advance and weighed by an aerosol weighing device (2) are dried and sieved to obtain required weight, aerosol powder is poured into an upper end plug (3-1) of a simulated fuel rod, a gas injection channel is fixed by the upper end plug (3-1), and finally a high-pressure gas bottle (1) is opened to start to inject gas into the simulated fuel rod (3) until the internal pressure of the simulated fuel rod (3) approaches a blasting set value, and the simulated fuel rod is kept for a period of time to ensure that the aerosol in the simulated fuel rod (3) is uniformly dispersed and deposited in a gas phase; The method comprises the steps of releasing aerosol, namely slowly lifting the gas pressure in a simulated fuel rod until the pressure in the simulated fuel rod is blasted after the internal pressure of the simulated fuel rod (3) is close to a blasting set value, blasting a rupture disc (4-2) at a fuel rod cladding rupture point, opening the rupture point (3-7) to be in an open state, starting releasing gas and aerosol in the fuel rod cladding (3-2) into a collecting device (5), starting to decrease the indication of a pressure gauge (3-6) along with the release of the gas and the aerosol until the release is finished, and recording the data of the release stage after the indication is reduced to normal pressure and no longer changed, and collecting aerosol powder in the collecting device (5) for measuring the particle size distribution of released aerosol particles by a wet particle size analyzer (6); The bench cleaning and repeating experiment are carried out, namely the break sealing device (4) and the simulated fuel rod (3) are disassembled after the release stage is finished, the simulated fuel rod is cleaned, no aerosol particle residue in the simulated fuel rod is ensured, the rupture disk (4-2) is replaced under other working conditions after the cleaning is finished, the repeated experiment under the same working condition is carried out, the repeated experiment is carried out at least twice, after the repeated experiment is finished, experimental data are preliminarily arranged, and whether the data are consistent with the actual process is checked; after the experiment under the same working condition is finished, changing the working condition to perform the experiment under the next working condition, and repeating the experimental steps; And (3) after the experimental operation is completed, processing experimental data recorded by the data acquisition system, and analyzing experimental phenomena and experimental results.

Description

Device and method for measuring aerosol release share and particle size distribution under lead bismuth fuel breakage Technical Field The invention belongs to the technical field of fission product release mechanism research, and particularly relates to a device and a method for measuring aerosol release share and particle size distribution under the condition of lead-bismuth stack fuel breakage. Background During operation of the reactor, the fuel assemblies of the core produce significant amounts of radioactive fission products during fission, however, fretting, foreign matter abrasion, chemical corrosion, irradiation creep and swelling, and the high pressure of the fission products within the fuel cladding may cause the fuel cladding to break, releasing the fission products to the coolant. The fission products released from the break include, in addition to the usual fission gases, non-gaseous fission products such as solid fission products and liquid fission products. In program calculation, generally, liquid fission products and solid fission products are uniformly simulated by aerosol particles, and currently, in the process of carrying out analysis of a lead bismuth stack mechanism source item, the aerosol share released by a break adopts an assumed value, so that uncertainty is introduced to a source item calculation result. Therefore, related experimental researches are needed to obtain key parameters of fission product migration process, such as gas release rate, total release share of aerosol after release is finished, and the like, aiming at the complex physical process of releasing the lead-bismuth fast reactor fission product from the fuel element to the liquid lead-bismuth alloy coolant, so as to provide support for model development and source analysis and calculation. Disclosure of Invention In order to solve the problems in the prior art, the invention aims to provide a device and a method for measuring the release share and the particle size distribution of aerosol under the breakage of lead-bismuth fuel, which can be used for researching the release characteristics of the aerosol and the fission gas under different fission gas pressures, different break sizes and different shapes. In order to achieve the above purpose, the present invention adopts the following technical scheme: The device for measuring the release share and the particle size distribution of the aerosol under the damage of the lead-bismuth fuel comprises a high-pressure gas tank 1, an aerosol weighing device 2, a simulated fuel rod 3, a break closure device 4, a collection device 5, a wet particle size analyzer 6, a pipeline valve and a flow pressure measuring instrument; the high-pressure gas tank 1 is used for providing gas required by the whole device and is connected with the upper port of the simulated fuel rod 3 through a ventilation pipeline with good air tightness; The aerosol weighing device 2 is used for weighing the used aerosol powder, so that the aerosol with specified quality is provided for the simulated fuel rod 3, and the aerosol is injected through the upper port of the simulated fuel rod 3, so that the pipeline residue and loss are reduced; The simulated fuel rod 3 is used for containing high-pressure aerosol and constructing break openings with different shapes and sizes on a fuel rod cladding, and the front-end gas enters the simulated fuel rod through the high-pressure gas tank 1 by referring to the size and the structural design of a real lead bismuth stack fuel rod, and the break opening closing device 4 is arranged on the fuel rod cladding break opening to serve as a gas outlet; The break closing device 4 has the function of closing the break of the cladding of the fuel rod, can construct a closed fuel rod inner space to bear high-pressure gas, is arranged on the simulated fuel rod 3 and is used as a gas outlet when being opened, and the rear end is connected with the collecting device 5; The collecting device 5 is used as a containing place of the aerosol released by the fuel rod, so that the subsequent sampling and measurement are facilitated, the position is arranged at the rearmost end of the gas flow path, and the released aerosol powder is subsequently collected from the collecting device and used for measuring the particle size distribution by the wet particle size analyzer 6; The wet particle size analyzer 6 is used for measuring the particle size distribution of aerosol particles of the sample gas, and collecting the aerosol to be measured from the collecting device 5. The gas in the high-pressure gas tank 1 is helium, and the aerosol powder is silicon dioxide powder. The high-pressure gas tank 1 is composed of a plurality of gas tanks for supplying sufficient gas to the device, and is connected with an aerosol injection section of the simulated fuel rod 3 through a pressure regulating valve so as to regulate the upper end pressure of the aerosol injection section. The aerosol weighing d