JP7250274B2 - Filter unit and volume reduction method for filter unit - Google Patents

Description

The present invention relates to a filter unit that collects dust in the air and a volume reduction method for such a filter unit.

Radioactive materials may be contained in exhaust gas from nuclear facilities. For this reason, filter units with advanced HEPA filters are used to remove radioactive materials from the exhaust. As the filter removes dust from the intake air, the amount of dust collected increases, and eventually clogging occurs. Therefore, the filter unit is periodically replaced and discarded.

In order to effectively utilize the storage space, the volume of the filter unit is reduced when discarding it. For example, Patent Literature 1 discloses a filter medium volume reduction device for a waste HEPA filter. In the filter medium volume reduction device of Patent Literature 1, the press mold is pressed against the filter medium by a hydraulic cylinder to compress and reduce the volume of the filter medium.

JP-A-62-113099

The volume of the filter unit can be greatly reduced by reducing the volume using the filter medium volume reduction device of Patent Document 1 or the like. However, with such a method, there is a possibility that the radioactive substances collected in the filter unit may scatter during the volume reduction work. Then, there is a risk that the work site will be contaminated with radioactive substances.

In view of such problems, the present invention provides a filter unit that can prevent scattering of radioactive substances during volume reduction work and prevent contamination of the work site with radioactive substances, and a volume reduction method thereof. It is intended to

In order to solve the above problems, a typical configuration of a filter unit according to the present invention includes a filter, an upper casing that supports an upper portion of the filter, a lower casing that supports a lower portion of the filter, and a filter unit disposed inside the upper casing. and a thermoplastic resin.

According to the above configuration, when the filter unit is heated, the thermoplastic resin arranged inside the upper casing melts. Then, the melted thermoplastic resin flows downward while adhering to the filter, and the entire surface of the filter is coated with the thermoplastic resin. By compressing the filter in this state, it is possible to reduce the volume without scattering radioactive substances from the filter. Therefore, it is possible to prevent scattering of radioactive substances during volume reduction work, and to prevent contamination of the work site with radioactive substances.

The filter may further include spacers linearly drawn at regular intervals, and the spacers may be made of a thermoplastic resin. According to such a configuration, when the filter unit is heated, not only the thermoplastic resin arranged inside the upper casing but also the spacer made of the thermoplastic resin are melted. Thereby, the surface of the filter can be more efficiently coated with the thermoplastic resin.

The cross section of the upper casing is U-shaped with a downward opening, and the cross section of the lower casing is U-shaped with an upward opening. Mating is good. This allows the compressed filter to be encapsulated by the upper and lower casings.

When the encapsulated filter unit is cooled, the filter is hardened by the resin, and the upper casing and the lower casing are filled with the hardened thermoplastic resin. Therefore, scattering of radioactive substances can be prevented during transportation and storage, and handling of the filter unit after volume reduction is facilitated.

The upper casing may have a taper that slopes toward the filter. As a result, the thermoplastic resin melted inside the upper casing can be suitably flowed along the surface of the filter.

In order to solve the above problems, a representative configuration of the filter unit volume reduction method according to the present invention is the above-described filter unit volume reduction method, wherein the filter unit is placed inside the upper casing by heating the filter unit. The thermoplastic resin is melted, the surface of the filter is coated with the melted thermoplastic resin, and the coated filter is compressed to reduce the volume. The constituent elements corresponding to the technical concept of the filter unit described above and their descriptions are also applicable to the volume reduction method of the filter unit.

ADVANTAGE OF THE INVENTION According to this invention, the filter unit which can prevent the scattering of a radioactive substance at the time of volume reduction work, and can prevent the contamination with a radioactive substance of a work site, and its volume reduction method can be provided.

It is a figure explaining the filter unit concerning this embodiment. It is a figure explaining the volume reduction method of the filter unit concerning this embodiment. It is a figure explaining the specimen for a heating test. It is a figure which shows the heating test result of a thermoplastic resin. It is a figure which shows the state of the filter at the time of a heating test.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in these embodiments are merely examples for facilitating understanding of the invention, and do not limit the invention unless otherwise specified. In the present specification and drawings, elements having substantially the same functions and configurations are denoted by the same reference numerals to omit redundant description, and elements that are not directly related to the present invention are omitted from the drawings. do.

FIG. 1 is a diagram illustrating a filter unit 100 according to this embodiment. FIG. 1(a) is an overall perspective view of the filter unit 100, and FIG. 1(b) is a sectional view taken along line AA of FIG. 1(a).

As shown in FIG. 1( a ), the filter unit 100 of this embodiment includes a filter 110 , an upper casing 120 and a lower casing 130 . The filter 110 (HEPA filter) is made of a sheet-like member made of glass fiber, and is arranged vertically between the upper casing 120 and the lower casing 130 in a folded state.

The filter 110 is formed with spacers 112 linearly drawn at regular intervals. The spacers 112 are resin and are applied before folding to maintain the spacing of the folded filters 110 . As a result, the folded shape of the filter 110 can be favorably maintained, and the filter performance can be maintained by preventing the uneven spacing of the pleats of the filter 110 . Moreover, it is possible to ensure the rigidity for the filter 110 to stand up between the upper casing 120 and the lower casing 130 .

The upper casing 120 and the lower casing 130 are members made of stainless steel, and as shown in FIG. It is U-shaped. The lower casing 130 has a cylindrical outer wall 130a and a cylindrical inner wall 130b, and has a U-shaped cross section with an upper opening. Upper casing 120 supports the upper portion of filter 110 and lower casing 130 supports the lower portion of filter 110 .

A bottom surface 102 is formed at the bottom of the filter unit 100 . That is, the upper casing 120 has an annular shape with a hole in the center, and the lower casing 130 has a disk shape. Therefore, the filter unit 100 as a whole becomes a cylinder with an upper opening. A seal member 122 (gasket) is arranged on the lower surface of the upper casing 120 to ensure airtightness. As a material of the sealing member 122, for example, fluororubber can be exemplified.

As shown in FIG. 1B, a feature of the filter unit 100 of this embodiment is that a thermoplastic resin 140 is arranged inside the upper casing 120 . Examples of the material of the thermoplastic resin 140 include polyolefin hot melt. However, it is not limited to this, and it is also possible to use thermoplastic resin 140 of other materials.

FIG. 2 is a diagram for explaining a method for reducing the volume of the filter unit 100 according to this embodiment. When reducing the volume of the filter unit 100, first, the filter unit 100 is heated to melt the thermoplastic resin 140 disposed inside the upper casing 120, as shown in FIG. 2(a).

The melted and liquefied thermoplastic resin 140 flows downward while adhering to the filter 110 . As a result, the entire surface of the filter 110 is covered or impregnated with the melted thermoplastic resin 140, as shown in FIG. 2(b). Thereafter, by compressing the coated filter 110, the volume of the filter unit 100 is reduced as shown in FIG. 2(c).

As described above, in the method for reducing the volume of the filter unit 100 of the present embodiment, when the volume of the filter unit 100 is reduced, the thermoplastic resin 140 inside the upper casing 120 is dissolved to remove the entire surface of the filter 110. Compress the filter 110 in the coated state. As a result, the volume of the filter unit 100 can be reduced without scattering radioactive substances from the filter 110 . Therefore, it is possible to prevent scattering of radioactive substances during volume reduction work, and to prevent contamination of the work site with radioactive substances.

Further, in this embodiment, the spacer 112 is made of a thermoplastic resin. Thereby, as shown in FIG. 2A, the spacer 112 is also dissolved when the filter unit 100 is heated. By dissolving the spacer 112 from the middle position in the vertical direction of the filter 110 , the entire surface of the filter 110 can be efficiently covered with the thermoplastic resin 140 . The thermoplastic resin used for the spacer 112 may be the same material as the thermoplastic resin 140 arranged inside the upper casing 120, or may be a different material. However, it preferably melts at the same temperature as the overlying thermoplastic resin 140 .

Furthermore, in this embodiment, as described above, the upper casing 120 has a U-shaped cross section with an open bottom, and the lower casing 130 has a U-shaped cross section with an open top. Thereby, as shown in FIG. 2(c), when the filter 110 is compressed, one of the upper casing 120 and the lower casing 130 fits into the other. This allows compressed filter 110 to be encapsulated by upper casing 120 and lower casing 130 .

When the encapsulated filter unit 100 is cooled, the filter 110 is hardened by the resin, and the upper casing 120 and the lower casing 130 are filled with the hardened thermoplastic resin 140 . Therefore, it is possible to prevent scattering of radioactive substances during transportation and storage, and facilitate handling of the filter unit 100 after the volume reduction.

Further, in this embodiment, as shown in FIG. 1B, the lower ends of the outer wall 120a and the inner wall 120b of the upper casing 120 are provided with tapers 124 that incline toward the filter 110. As shown in FIG. This makes it possible to guide the thermoplastic resin 140 along the surface of the filter 110 when the thermoplastic resin 140 flows downward as shown in FIG. 2(b).

In addition, as shown in FIG. 1B, in the filter unit 100 of the present embodiment, the thermoplastic resin 142 is also arranged inside the lower casing 130, but it is not limited to this. By arranging the thermoplastic resin 140 at least inside the upper casing 120, the effects described above can be obtained.

However, it is preferable that the thermoplastic resin 142 placed in the lower casing 130 also melts at the same temperature as the thermoplastic resin 140 in the upper casing 120 . By melting both the thermoplastic resin 140 and the thermoplastic resin 142, the lower end of the filter 110 can be tilted, and the volume can be further reduced.

FIG. 3 is a diagram for explaining a specimen for a heating test. 3(a) is an overall perspective view of the specimen 200, and FIG. 3(b) is a cross-sectional view taken along line BB of FIG. 3(a). Constituent elements common to those of the filter unit 100 of FIG. 1 are denoted by the same reference numerals, and descriptions thereof are omitted.

While the filter unit 100 in FIG. 1 was cylindrical, the specimen 200 in FIG. 3(a) was rectangular (flat). An upper casing 120 and a lower casing 130 are provided above and below the filter 110 . Similar to the filter unit 100 , a thermoplastic resin 140 is placed inside the upper casing 120 and a thermoplastic resin 142 is placed inside the lower casing 130 . The filter 110 is formed with spacers 112 that are linearly drawn at regular intervals.

FIG. 4 is a diagram showing the results of the heating test of the thermoplastic resin 140, and is a list of test conditions (heating temperature and heating time) and test results (thermoplastic resin coverage and coverage status). FIG. 5 is a diagram showing the state of the filter 110 during the heating test. FIG. 5(a) is a diagram showing the state of the filter 110 in test 1 (160° C.) in FIG. 4, and FIG. 5(b) shows the state of the filter 110 in test 5 (180° C.) in FIG. FIG. 5(c) is a diagram showing the state of the filter 110 in test 9 (200° C.) of FIG.

When the heating temperature was 160° C. as shown in Tests 1-4 of FIG. 4, the coverage was in the range of 25-30%. In this case, as shown in FIG. 5A, the filter 110 is covered with the thermoplastic resin 140 only in the area above the line L1. From this, it can be understood that the thermoplastic resin 140 cannot be sufficiently dissolved when the heating temperature is 160°C.

On the other hand, when the heating temperature was 200° C. as shown in Test 9 of FIG. 4, the coverage was 80%. In this case, as shown in FIG. 5(c), the filter 110 is not covered with the thermoplastic resin 140 because the area above the line L3 is exposed. From this, it can be understood that if the heating temperature is 200° C., the viscosity of the melted thermoplastic resin 140 is too low, and the thermoplastic resin 140 flows too far downward in a short time of 15 minutes.

When the heating temperature was 180° C. as in test 5 in FIG. 4, the coverage was 80%. In this case, as shown in FIG. 5(b), the filter 110 is coated with the thermoplastic resin 140 over the area above the line L2, that is, most of the area. Therefore, when the heating time was increased, 90% of the filter 110 was covered with the thermoplastic resin 140 in Test 6 (30 minutes), and 100% of the filter 110 was covered with the thermoplastic resin 140 in Test 7 (45 minutes). coated.

After that, for confirmation, in Test 8 (60 minutes) in which the heating time was further increased, a region not covered with the thermoplastic resin 140 was formed on the upper portion of the filter 110 as in Test 9. From this, it can be understood that it is preferable to set the heating temperature to 180° C. and the heating time to 45 minutes for the thermoplastic resin 140 used this time. However, the heating temperature and the heating time shown in FIG. 4 depend on the type of the thermoplastic resin 140 and various conditions, and the heating temperature and the heating time are numerical values that should be appropriately set.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope described in the claims, and these also belong to the technical scope of the present invention. Understood.

INDUSTRIAL APPLICABILITY The present invention can be used for a filter unit that collects dust in the air and a volume reduction method for such a filter unit.

DESCRIPTION OF SYMBOLS 100... Filter unit 102... Bottom surface 110... Filter 112... Spacer 120... Upper casing 122... Seal member 124... Taper 130... Lower casing 140... Thermoplastic resin 142... Thermoplastic resin 200... specimen

Claims (5)

a filter that is compressible and collects radioactive material ;
an upper casing that supports an upper portion of the filter;
a lower casing that supports a lower portion of the filter;
a thermoplastic resin disposed inside the upper casing in contact with the filter and melted by heating to cover the entire surface of the filter ;
A filter unit comprising: Further comprising spacers linearly drawn at regular intervals on the filter,
2. A filter unit according to claim 1, wherein said spacer is made of thermoplastic resin. The cross section of the upper casing is U-shaped with an open bottom,
The cross section of the lower casing is U-shaped with an upper opening,
3. A filter unit according to claim 1, wherein one of said upper casing and said lower casing fits into the other when said filter is compressed. The filter unit according to any one of claims 1 to 3, wherein the upper casing has a taper that slopes toward the filter. A filter unit volume reduction method according to any one of claims 1 to 4,
melting the thermoplastic resin disposed inside the upper casing by heating the filter unit;
coating the entire surface of the filter with the molten thermoplastic resin;
A method for reducing the volume of a filter unit, comprising compressing the coated filter to reduce the volume.

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