CN-117030935-B - Freezing method effect simulation system for emergency treatment of nuclear leakage and evaluation method

CN117030935BCN 117030935 BCN117030935 BCN 117030935BCN-117030935-B

Abstract

The invention discloses a freezing method effect simulation system and an evaluation method for emergency treatment of nuclear leakage, wherein the simulation system comprises a permeation resistance experiment system, a low-temperature cold bath system and a freezing wall monitoring system, the freezing wall monitoring system comprises a radial-axial combined strain gauge, an acoustic emission test system and a CT scanning system, the radial-axial combined strain gauge is arranged near a freezing pipe and comprises a radial strain gauge and an axial strain gauge which are respectively used for monitoring frost heaving strain generated in the radial and axial directions in the forming process of the freezing wall, the acoustic emission test system is arranged near the freezing pipe and is used for collecting acoustic emission signals, the acoustic emission test system comprises a waveguide rod, an acoustic emission sensor and a signal amplifier, the CT scanning system comprises an X-ray source and a detector and is used for monitoring the nuclear species permeation condition and the porosity of the freezing wall area, and the collected frost heaving strain, acoustic emission signals and the porosity are sent to a data and image processing system for analysis. The invention can accurately monitor and evaluate the seepage resistance of the freezing wall, and can be widely applied to the field of nuclear leakage treatment.

Inventors

LI GANG
LIU JIANKUN
ZHU JINGZE
KANG MINGLIANG
ZHENG YANG
Zeng Xuanjun
REN ZHIFENG

Assignees

中山大学
南方海洋科学与工程广东省实验室(珠海)

Dates

Publication Date: 20260505
Application Date: 20230727

Claims (8)

1. The freezing method effect simulation system for emergency treatment of nuclear leakage is characterized by comprising a seepage blocking experimental system, a low-temperature cold bath system and a freezing wall monitoring system; The seepage-resistant experimental system comprises a water supply tank, a peristaltic pump, a first filter screen, a second filter screen, a first water pipe, a second water pipe, a model box, a plurality of freezing pipes and a waste liquid recovery box, wherein the water supply tank is connected with a first side surface of the model box through the first water pipe, the peristaltic pump is arranged on the first water pipe, a water supply valve is further arranged on the first water pipe, the first filter screen is arranged in the model box and forms a water inlet chamber with the first side surface, the waste liquid recovery box is connected with a second side surface of the model box through the second water pipe, the second filter screen is arranged in the model box and forms a water outlet chamber with the second side surface, the second water pipe is further provided with a water outlet valve, the first side surface and the second side surface are opposite, the first side surface is parallel to the first side surface, the second filter screen is parallel to the second side surface, the freezing pipes are arranged in the model box and form a water inlet chamber with the first filter screen and the second filter screen, the freezing pipes are parallel to the second filter screen, and the freezing pipes are arranged in parallel to each other, and the freezing pipes can be arranged in the parallel to each other, and the freezing pipes are arranged in the two parallel to the positions; The low-temperature cold bath system is connected with the freezing pipe through a water inlet pipe and a water outlet pipe, exchanges antifreeze with the freezing pipe through a built-in circulating pump, and enables the temperature of the antifreeze in the water inlet pipe and the temperature of the antifreeze in the water outlet pipe to be in preset constant values; The freezing wall monitoring system comprises a radial-axial combined strain gauge, an acoustic emission testing system, a CT scanning system and a data and image processing system, wherein the radial-axial combined strain gauge and the acoustic emission testing system are arranged between a first filter screen and a second filter screen, the radial-axial combined strain gauge is used for monitoring frost heaving strain generated by a freezing wall in a radial direction and an axial direction in a forming process of the freezing wall in a model box, the acoustic emission testing system is used for collecting acoustic signals generated by volume expansion of frozen soil due to water ice phase change in the forming process of the freezing wall, a nuclide solution comprising KI is used as CT contrast agent of the CT scanning system, the CT scanning system is used for emitting X-rays to the area where the freezing wall is located in the model box so as to obtain seepage information and porosity of the nuclide solution in the area where the freezing wall is located, and the data and the image processing system is used for determining the seepage resistance of the freezing wall according to at least one of the frost heaving strain, characteristic parameters corresponding to the acoustic signals and the porosity; a pull ring is arranged on each freezing pipe and used for pulling the pull ring to adjust the pipe diameter of the freezing pipe; All the freezing pipes are arranged on one sliding rail, and each freezing pipe can move on the sliding rail; the radial-axial combined strain gauge comprises a radial strain gauge and an axial strain gauge; the radial strain gauge consists of a closed steel fiber coil and a first film strain gauge adhered to the surface of the steel fiber coil, wherein the surface of the steel fiber coil has a set roughness so as to fix the position of the radial-axial combined strain gauge; the axial strain gauge consists of four steel fibers fixed at the extending positions of the steel fiber coil in the radial directions of up, down, front and back and a second film strain gauge bonded at the contact position of each steel fiber and the steel fiber coil, and each steel fiber points to the geometric center of the steel fiber coil; Wherein the plane of the steel fiber coil is parallel to the first filter screen and the second filter screen.
2. The freezing method effect simulation system for emergency treatment of nuclear leakage according to claim 1, wherein a cold bath is arranged in the low-temperature cold bath system and is used for containing antifreeze, a plurality of circles of refrigerating pipes are arranged around the periphery of the inner wall of the cold bath, and the refrigerating pipes are used for controlling the temperature of the antifreeze to be a preset constant value.
3. The system of claim 1, wherein the radial strain gauge acquires a first resistance value when the resistance value of the sensitive grating inside the first thin film strain gauge changes due to expansion of the freeze wall to deform the steel fiber coil; when the freezing wall expands to deform the steel fiber to change the resistance value of the sensitive grid in the second film strain gauge, acquiring a second resistance value by the axial strain gauge; Wherein the first resistance value and the second resistance value are used as the frost heaving strain.
4. The system of claim 1, wherein the CT scanning system comprises an X-ray source and a detector; The X-ray source is used for generating X-rays and irradiating the region where the freezing wall is positioned in the model box; The detector is used for receiving an X-ray signal generated by the X-ray penetrating through the frozen wall in the model box, converting the X-ray signal into a first digital signal and transmitting the first digital signal to the data and image processing system; the data and image processing system is used for carrying out three-dimensional reconstruction on the area where the freezing wall is located according to the first digital signal to obtain a reconstruction model, and determining seepage information of the nuclide solution penetrating the freezing wall and the porosity of the area where the freezing wall is located according to the reconstruction model.
5. The freeze effect simulation system for emergency treatment of nuclear leakage of claim 1, wherein the acoustic emission testing system comprises a waveguide rod, an acoustic emission sensor, and a signal amplifier; the waveguide rod is used for transmitting the acoustic signal; the acoustic emission sensor is used for collecting the acoustic signals; The signal amplifier is used for filtering and amplifying the sound signal, converting the sound signal after filtering and amplifying into a second digital signal, and then transmitting the second digital signal to the data and image processing system.
6. The system of claim 5, wherein the data and image processing system is configured to extract the number of rings, the number of accumulated events, and the accumulated energy from the second digital signal as the corresponding characteristic parameters of the acoustic signal; The method comprises the steps of setting a frequency of ringing, wherein the frequency of ringing is the frequency that the amplitude of an acoustic signal crosses a preset threshold voltage in a set time period, the accumulated event number is the number of acoustic emission events obtained by wave-striking identification in the set time period, the acoustic signal exceeds a signal threshold value, any signal of data acquired by any channel of the data and an image processing system is used as a wave-striking, a local change of acoustic emission primary material is generated as an acoustic emission event, and the accumulated energy is the area under the acoustic emission event detection envelope curve and is used for reflecting the relative energy and intensity of the acoustic emission event.
7. The system of claim 1, wherein the data and image processing system is configured to determine the permeability resistance of the freeze wall based on at least one of the frost heaving strain, the characteristic parameter corresponding to the acoustic signal, and the porosity, comprising: The data and image processing system is used for determining a comprehensive evaluation expression according to the frost heaving strain, the characteristic parameters corresponding to the acoustic signals and the porosity, and determining the permeability resistance of the freezing wall according to the comprehensive evaluation expression; The comprehensive evaluation expression is: The method comprises the steps of determining a characteristic parameter of acoustic signals, wherein k i is an evaluation index of permeability resistance, N e is the porosity, sigma a is axial strain in frost heaving strain, sigma r is radial strain in frost heaving strain, characteristic parameters corresponding to the acoustic signals comprise ringing times, accumulated event numbers and accumulated energy, N r ,N s ,A e is the ringing times, accumulated event numbers and accumulated energy respectively, alpha, beta and gamma are coefficients of the porosity, the frost heaving strain and the characteristic parameters respectively, a is a weight ratio of the axial strain, b is a weight ratio of the radial strain, and c, d and e are weight ratios of the ringing times, the accumulated event numbers and the accumulated energy respectively.
8. A freezing method effect evaluation method of emergency treatment nuclear leakage, applied to the data and image processing system in a freezing method effect simulation system of emergency treatment nuclear leakage according to any one of claims 1 to 7, the evaluation method comprising: Acquiring frost heave strain generated in the radial direction and the axial direction in the forming process of the freezing wall in the model box, wherein the frost heave strain is measured by a radial-axial combined strain gauge; Acquiring an acoustic signal generated by the expansion of the frozen soil volume caused by the phase change of water ice in the frozen wall forming process acquired by an acoustic emission testing system, and determining characteristic parameters corresponding to the acoustic signal, wherein the characteristic parameters comprise ringing times, accumulated event numbers and accumulated energy; Acquiring seepage information and porosity of a nuclide solution in a region where a freezing wall is positioned in the model box by transmitting X-rays to the region where the freezing wall is positioned by a CT scanning system; Determining a comprehensive evaluation expression according to the frost heaving strain, the characteristic parameters corresponding to the acoustic signals and the porosity, and determining the seepage resistance of the frozen wall according to the comprehensive evaluation expression; The comprehensive evaluation expression is: Wherein k i is an evaluation index of permeability resistance, N e is the porosity, sigma a is the axial strain in the frost heaving strain, sigma r is the radial strain in the frost heaving strain, N r ,N s ,A e is the number of rings, the number of accumulated events and the accumulated energy respectively, alpha, beta, gamma is the coefficient of the porosity, the frost heaving strain and the characteristic parameter respectively, a is the weight ratio of the axial strain, b is the weight ratio of the radial strain, c, d, e is the weight ratio of the number of rings, the accumulated event number and the accumulated energy respectively.

Description

Freezing method effect simulation system for emergency treatment of nuclear leakage and evaluation method Technical Field The invention relates to the field of nuclear leakage treatment, in particular to a freezing method effect simulation system for emergency treatment of nuclear leakage and an evaluation method. Background Once the disposal site where the radioactive nuclear waste is located is destroyed by natural disasters or human activities, a large amount of nuclear waste will break the engineering and natural barriers of the disposal site causing unpredictable losses as groundwater flows into the biosphere. Because the frozen soil has the advantages of low permeability, deformation resistance, radiation resistance and the like, the artificial stratum freezing method for blocking nuclear waste water leakage of the nuclear power station in the prior art has good application and popularization prospects, however, the theory is obviously lagged behind practice due to the lack of an effective simulation system and an evaluation means in the application effect of the prior art. At present, the freezing method is mostly applied to subway construction and vertical shaft and tunnel digging and building engineering, and the quick and flexible adjustment of parameters of the freezing pipe is difficult to realize in the research of the simulation device and the system of the freezing method. In addition, the freezing method for emergency treatment of nuclear leakage is characterized in that the freezing method is rapid in seepage resistance, higher requirements are put forward on accurate and rapid evaluation of the freezing wall from formation to stable process, but the prior art cannot meet accurate monitoring of seepage resistance of the freezing wall, and meanwhile, the evaluation means for implementation effect of the freezing method are single. Disclosure of Invention In view of the above, the present invention provides a freezing method effect simulation system and an evaluation method for emergency treatment of nuclear leakage, so as to accurately monitor and evaluate the permeability resistance of the freezing wall. The invention provides a freezing method effect simulation system for emergency treatment of nuclear leakage, which comprises a seepage resistance experiment system, a low-temperature cold bath system and a freezing wall monitoring system; The seepage-resistant experimental system comprises a water supply tank, a peristaltic pump, a first filter screen, a second filter screen, a first water pipe, a second water pipe, a model box, a plurality of freezing pipes and a waste liquid recovery box, wherein the water supply tank is connected with a first side surface of the model box through the first water pipe, the peristaltic pump is arranged on the first water pipe, a water supply valve is further arranged on the first water pipe, the first filter screen is arranged in the model box and forms a water inlet chamber with the first side surface, the waste liquid recovery box is connected with a second side surface of the model box through the second water pipe, the second filter screen is arranged in the model box and forms a water outlet chamber with the second side surface, the second water pipe is further provided with a water outlet valve, the first side surface and the second side surface are opposite, the first side surface is parallel to the first side surface, the second filter screen is parallel to the second side surface, the freezing pipes are arranged in the model box and form a water inlet chamber with the first filter screen and the second filter screen, the freezing pipes are parallel to the second filter screen, and the freezing pipes are arranged in parallel to each other, and the freezing pipes can be arranged in the parallel to each other, and the freezing pipes are arranged in the two parallel to the positions; The low-temperature cold bath system is connected with the freezing pipe through a water inlet pipe and a water outlet pipe, exchanges antifreeze with the freezing pipe through a built-in circulating pump, and enables the temperature of the antifreeze in the water inlet pipe and the temperature of the antifreeze in the water outlet pipe to be in preset constant values; The freezing wall monitoring system comprises a radial-axial combined strain gauge, an acoustic emission testing system, a CT scanning system and a data and image processing system, wherein the radial-axial combined strain gauge and the acoustic emission testing system are arranged between a first filter screen and a second filter screen, the radial-axial combined strain gauge is used for monitoring frost heaving strain generated by a freezing wall in a radial direction and an axial direction in a forming process of the freezing wall in a model box, the acoustic emission testing system is used for collecting acoustic signals generated by volume expansion of frozen soil due to water ice phase change in the