RU2457477C1 - Method of inspecting contents of closed volume - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: audio or ultrasonic radiation is successively transmitted through an acoustic line in form of a solid-state body inside the closed volume towards the contents of the closed volume; the reflected echo signal is picked up and useful information is obtained by comparing the picked up reference and control echo signals, wherein during the inspection process, pressure inside the closed volume is measured and deviation of pressure from the initial pressure is converted to displacement of the controlled point of reflection of radiation in the acoustic line.

EFFECT: possibility of remote inspection of the state of contents in a closed volume.

2 dwg

Description

FIELD OF THE INVENTION

The claimed invention relates to methods for monitoring the state of the contents of a closed volume under conditions of restriction or inability to access it and the inability to supply wired communication channels. For example, this is the case with the use of thick-walled protective containers of spent nuclear fuel (SNF) and long-term storage of spent nuclear fuel or radioactive waste (RW) in the nuclear industry, as well as environmentally hazardous facilities, explosives and chemicals.

As a rule, the parameters of the gas medium inside the canisters (containers) with SNF are subject to measurement and control. At the same time, the mentioned containers are several sealed layers of metal, concrete and intermediate gas gaps. Laying wired communication channels in these conditions is impractical or impossible due to the danger of reducing the reliability of protection. The presence of power sources inside the protection is excluded, the radio communication is completely shielded.

The task is complicated by the fact that sensors that monitor, for example, temperature or pressure, as well as the method of supplying signals from them to the central signal station, must have a non-electric principle of operation. The absence of sparks and electric current is also one of the main conditions for safe storage.

State of the art

In some cases, it is possible to monitor the contents through viewing windows (US 3433957 A. 18/03/1969; GB 995003 A. 10/06/1965). One of the windows is described by the invention according to the patent of the Russian Federation No. 2310932 (application No. 2005138004/06, 06.12.2005, G21F 7/00). However, visual observation is often difficult because containers are buried or have several shells, you can observe with the help of windows only the appearance of the shell or contents that do not always reflect ongoing processes, etc.

Most often, the result of unregulated processes occurring in the considered closed volumes can be a violation of their tightness and environmental pollution. Therefore, the most common means of control over such objects is tightness control, leak detection.

Various means are known (methods and devices) for determining leakage, leakage of liquids and gases from reservoirs, pools, etc.

To detect small leaks, leakage indicators are used, as a rule, these are chemicals with a coloring effect, or they are radioactive substances. For example, in A.S. USSR No. 1439427 "Method for detecting leaks in the bottoms of ground tanks" shows a method using sodium permanganate of a characteristic color to determine leaks at the junction of the bottom and tank body. However, the use of dyes is applicable only in the process of checking equipment, but not in operating it. In addition, the sorption of these substances on the surfaces of equipment materials does not allow them to be used if there are restrictions on the technological requirements for the contents of tanks and other technological equipment. A completely inconvenient method with the use of dye to control buried tanks, as well as if the outer surfaces of the tanks are at least partially covered by auxiliary equipment.

On October 10, 2007, an application for invention No. 94003599/28 was published containing a description of a technical solution entitled “A method for detecting leaks in closed process systems and tanks,” for which RF patent No. 2092803 (IPC G01M 3/20) was issued. The essence of the tank control: a tracking radioactive indicator - tritium water - is introduced into the tank filled with water, starting from the bottom and then gradually to the surface. By increasing the concentration of tritium in a controlled stream, leaks are judged. The disadvantages of the method are practically the same as those described above.

Known means for detecting end-to-end defects in the walls of containers filled with liquid or gas, directly by registering the resulting medium. For example, on April 7, 1986, an invention was published under the name "Device for searching for leaks in products," to which A.S. USSR No. 1223073, IPC G01M 3/04. The device comprises a leak detector, a probe connected to it, an element selective for sample gas, and the probe is made in the form of a bundle of hollow fibers. The method of operation of the device is to register a cloud of test gas that has penetrated from the product through a through defect. This tool is convenient for checking equipment, but not during operation.

The method of testing the cylindrical products for leaks (AS USSR No. 1740999, IPC G01M 3/04, published June 15, 1992) consists in registering the control gas in the product when moving the closed chamber with gas along the axis of the product. The method is applicable for checking products of a certain shape, but not during operation.

Other means are known for monitoring tightness (JP 10068793; RU 2136061 C1, 08.27.1999).

Acoustic methods and devices for determining the location of a leak, i.e. based on the reception of noise from an effluent jet and the conversion of this noise into electrical voltage (for example, the invention according to RF patent No. 2249802, IPC G01M 3/24, F17D 5/02, application published 10.10.2003). The application of these methods is difficult at medium and low levels of leakage (not more than 500 l / h), since in this case acoustic disturbances are hardly noticeable against the anthropogenic background, and the defects themselves causing leakage are practically not visible. The flow indicators are significantly affected by random internal currents in the pool, caused, for example, by the need to pump water to maintain the level.

As a prototype of the claimed invention, a method of ultrasonic monitoring of objects in a protected area for which a patent of the Russian Federation No. 2257618 is issued (IPC G08B 13/184, G01S 1/72, publication July 27, 2003).

The method consists in sequentially transmitting sound or ultrasonic radiation from the source outside through the sound duct in the form of a solid body towards the controlled area (closed volume content), registering the reflected echo signal in the form of a time scan of peak pulses and obtaining useful information by comparing the recorded reference and control echoes -signals.

The method is convenient as a means of remote monitoring the presence or absence of a storage object in a specified place, as well as an attempt to move it or damage it. However, using this method, it is difficult to determine the state of the contents of the object.

According to the applicant and the authors, the known method is quite suitable as a prototype of the claimed invention, because with its help, the state (presence, absence, change of location) of its contents (protected object) is monitored in a closed volume (room).

The task of the claimed invention is to provide a method that provides remote monitoring of the state of the contents of the object, in other words, the state of the contents of the closed volume. The technical result, due to which the task is solved, is to provide, during monitoring, the connection between the change in pressure inside the enclosed volume, and sound or ultrasonic radiation, which allows obtaining useful information without access to the inside of the volume.

Disclosure of invention

To obtain the specified technical result in a method of controlling the contents of a closed volume, which consists in sequentially transmitting sound or ultrasonic radiation from the source through the sound pipe in the form of a solid body into a closed volume in the direction to the contents of the closed volume, registering the reflected echo signal and obtaining useful information by comparison registered reference and control echoes, according to the invention, in the process of monitoring measure the pressure inside the closed volume, and the deviation of pressure from the original is converted into the displacement of the controlled place of radiation reflection in the sound duct.

The presence of signs "in the control process measure the pressure inside the enclosed space, and the deviation of the pressure from the source is converted to the offset of the controlled place of reflection of radiation in the sound pipe", distinguishing the claimed invention from the prototype, indicates the compliance of the claimed invention with the condition of patentability "novelty".

Signs that distinguish the claimed invention from the prototype are not identified in the technical solutions for a similar purpose. This allows us to conclude that the claimed invention meets the condition of patentability "inventive step".

The implementation of the invention

To confirm the industrial applicability of the invention, consider an example implementation of the claimed invention.

Figure 1 shows a section along the vertical plane of the container with SNF, figure 2 - the relative position of the elements (top view, more about them below), providing a controlled place of reflection of radiation in the sound duct.

The container is a casing 1 with covers 2 and 3. Inside the container, spent fuel canisters are placed (contents of a closed volume, depicted as body 4).

In this technical solution, to determine the state of the contents of the closed volume, the pressure inside the container 1-3 is measured. To measure this parameter, a stand 5 is placed on the surface A of the cover 3 with a pressure sensor 6 in the form of a bellows. The bellows 6 is rigidly fixed with one bottom on the strut 5. On the free bottom B of the bellows 6, two rollers 8 are mounted opposite each other using the bracket 7. The rollers 8 are rotatable around their central axis (in this case, around the vertical axis) and are located constant contact with the sound duct 9.

The sound pipe 9 is mounted on the cover 3 and has a conical extension 10 towards the cover 3. In order to clarify the speed of the signal through the sound pipe 9 at the time of control, at least two reference cuts are applied to the sound pipe 9 near the extension 10 at a given distance from each other (not shown).

Between the covers 2 and 3 in the contact zone of the extension 10 of the sound duct 9 with the cover 3, two disk springs 11 are placed in constant contact with the covers 2 and 3 and perform the function of the sound duct. Outside, on the cover 2, above the springs 11, an ultrasonic radiation source-receiver 12 is mounted connected to the echo signal processing unit.

The control method is implemented as follows.

After placement of SNF in the housing 1 (contents 4) and assembly of the housing 1 with covers 2 and 3, an ultrasonic pulse is applied to the radiation source 12 passing alternately through the elements of the sound-conducting system formed by the cover 2 — plate springs 11 — cover 3 — by extension 10 on the sound pipe 9 - sound pipe 9.

Ultrasound is reflected from the tip of the sound pipe 9, the echo signal passes in the opposite direction along the sound-conducting system to the source-receiver 12. Using the processing unit, the echo signal is recorded in the form of a time scan and stored as a constant reference. During the passage of the echo signal, a reflection pulse (in the form of a peak) is recorded at the place of contact of the rollers 8 with the sound duct 9. This place is a controlled place for the reflection of radiation. At the time base there are also marks of reflection pulses in the form of peaks of different sizes at the joints “source-receiver 12 and cover 2”, “cover 2 and disk spring 8”, “disk spring 8 between each other”, “spring 8 and cover 3” “Cover 3 and extension 10 of sound duct 9”. Reference notches also form reflection pulses.

When storing the contents 4 in it, processes may occur with the formation of external factors affecting the properties of the material of the sound duct 9, respectively, the speed of sound transmission in the sound duct 9 may change. Registration of reflection pulses in the reference notches allows these changes to be taken into account.

The echo signal recorded at the beginning of the storage of the contents 4 in a closed volume is taken as a reference.

In the process of storing spent nuclear fuel (contents 4), pulses of ultrasonic radiation are periodically or constantly supplied and echo signals are recorded, which are accepted as control ones.

In the case of a change in pressure in the closed volume of the container 1-3, due to the processes occurring in the contents 4, the bellows 6 perceives a change in the difference between its internal pressure and the pressure from the outside, its linear size changes (distance from one bottom to the other).

The rollers 8 move together with the bottom B of the bellows 6 along the sound duct 9, i.e. there is a shift in the controlled place of reflection of radiation in the sound pipe 9. When registering an echo signal, the shift of the controlled place of reflection is detected by the changed distance between the reflection pulses at the tip of the sound pipe 9 and in the controlled place of reflection of radiation.

The actions of personnel depend on how bellows are configured 6. If it is configured to give a signal when a critical pressure is reached and above it, then measures are immediately taken to stop the unregulated processes that occur in the contents of a closed volume. In other cases, preparation for the necessary actions begins, and when the pressure reaches a critical value, the necessary actions are taken.

Industrial applicability

Thus, the information presented indicates the fulfillment of the following set of conditions when using the claimed invention:

- means that embody the inventive method in its implementation, are intended to monitor the state of the contents of the closed volume in conditions of limitation or inability to access it and the inability to supply wired communication channels;

- for the proposed method in the form in which it is described in the claims, the possibility of its implementation using the means and methods described in the application and known prior to the priority date is confirmed.

Therefore, the claimed invention meets the condition of "industrial applicability".

Claims (1)

A method of controlling the contents of a closed volume, which consists in sequentially transmitting sound or ultrasound radiation from a source through a sound duct in the form of a solid body into a closed volume towards the contents of a closed volume, recording the reflected echo signal and obtaining useful information by comparing the recorded reference and control echo signals, characterized in that in the control process measure the pressure inside a closed volume, and the pressure deviation from the original transform t in the offset of the controlled place of reflection of radiation in the sound duct.

Images