JP6368079B2 - Radioactive waste volume reduction treatment apparatus and volume reduction treatment method - Google Patents

Description

  The technology disclosed in the present specification relates to a radioactive waste volume reduction processing apparatus and a volume reduction processing method.

  Patent Document 1 discloses a volume reduction processing apparatus for radioactive waste. Volume reduction treatment equipment reduces and stabilizes radioactive waste (including used ion exchange resin) generated at nuclear power plants and facilities that handle radioactive materials to reduce the volume of waste with a relatively high level of radioactivity. Used to make The volume reduction processing device of Patent Document 1 includes a dry distillation section, a filter section, and a powder storage section. The dry distillation part and the filter part are cylindrical. The upper part of the powder storage part has a cylindrical shape, and the lower part has a conical shape (strictly, a truncated cone shape) whose diameter decreases as it goes downward. The diameter of the cylindrical part of the powder storage part is made larger than the diameters of the dry distillation part and the filter part. The dry distillation part and the filter part are arranged in parallel on the upper surface of the powder storage part. The dry distillation section and the filter section are in communication with the powder storage section. In the carbonization section, radioactive waste is carbonized. In the filter unit, exhaust gas generated during dry distillation is filtered. The powder storage unit stores the residue generated during dry distillation and the dust generated when the exhaust gas is filtered. Residue and dust slide down the wall surface of the conical portion of the powder storage unit and are stored at the bottom of the powder storage unit.

JP 2012-116997 A

  In the volume reduction processing apparatus of Patent Document 1, the dry distillation part and the filter part share one powder storage part. That is, the dry distillation part, the filter part, and the powder storage part are integrally formed, and although it can be made compact as a whole, the apparatus is relatively large in size. In particular, the conical portion of the powder storage section needs to be inclined at an angle greater than the repose angle of the residue and dust so that the residue and dust can slide smoothly without stagnation. For this reason, if the diameter of the powder storage portion is large, the height of the conical portion is increased accordingly, and as a result, the height of the volume reduction processing device is increased. Therefore, in the volume reduction processing apparatus of patent document 1, there exists a possibility that it may be unable to install depending on space restrictions depending on a place. Furthermore, since the residue generated during dry distillation is stored in the powder storage unit regardless of the mass, there is a possibility that the subsequent processing may not be appropriately performed depending on the type of radioactive waste to be processed.

  In this specification, compared with the conventional volume reduction treatment apparatus, the radioactive waste that improves the degree of freedom of the installation location and can treat the residue more appropriately even when a residue with large variation in mass occurs. A volume reduction processing apparatus and a volume reduction processing method are disclosed.

  The radioactive waste volume reduction processing device disclosed in this specification includes a first container, a second container, and a pipe connecting the first container and the second container. The first container includes a dry distillation section, external heating means for heating the dry distillation section from the outside, radioactive waste supply means for supplying radioactive waste to one end of the dry distillation section, and first superheat for supplying superheated steam to the dry distillation section. It has a 1st powder storage part arrange | positioned at a water vapor | steam supply means and the other end of a dry distillation part. A dry distillation part discharges the residue and exhaust gas which generate | occur | produce by thermally decomposing radioactive waste from the other end. The 1st residue which is a part of residue discharged | emitted from the other end of a dry distillation part is stored by the 1st powder storage part. The remainder of the residue discharged from the other end of the dry distillation section and having a mass smaller than that of the first residue is supplied to the second container through the pipe together with the exhaust gas. The second container includes a filter unit that filters the exhaust gas supplied from the pipe, and a second powder storage unit that is disposed at one end of the filter unit and stores the second residue supplied from the pipe.

  In said volume reduction processing apparatus, another powder storage part is arrange | positioned at the other end of a dry distillation part, and the end of a filter part, respectively. Thereby, it is set as the structure which isolate | separates the container (1st container) which has a carbonization part, and the container (2nd container) which has a filter part, and connects these containers by piping. According to this configuration, the size of the first container and the second container as a single unit can be reduced as compared with the conventional volume reduction processing apparatus, and the degree of freedom of the installation location when installing each container is improved. Moreover, the residue discharged | emitted from the other end of a dry distillation part is distinguished and stored in two powder storage parts by the mass of a residue. For this reason, even if there is a large variation in the mass of the residue discharged from the dry distillation section, this residue is stored separately in each powder storage section, and the variation in the mass of the residue stored in each powder storage section is small . Therefore, the residue of each powder storage part can be processed appropriately.

  The radioactive waste volume reduction processing method disclosed in the present specification includes a thermal decomposition step, a first storage step, a transfer step, a filtration step, and a second storage step. In the pyrolysis process, the radioactive waste is pyrolyzed with superheated steam. In a 1st storage process, the 1st residue which is a part of residue generated by the thermal decomposition process is transferred to the 1st powder storage part, and is stored. In the transfer step, the remaining residue generated by the pyrolysis step and having a smaller mass than the first residue is transferred to the second powder storage unit via the pipe together with the exhaust gas generated by the pyrolysis step. To do. In the filtration step, the exhaust gas transferred to the second powder storage unit is transferred to the filter unit and filtered through the filter unit. In the second storage step, the second residue transferred to the second powder storage unit is stored in the second powder storage unit. In the transfer step, the second residue is transferred to the second powder reservoir by exhaust gas. According to this volume reduction processing method, the above volume reduction processing apparatus can be suitably realized.

  Details of the technology disclosed in this specification and further improvements will be described in detail in the detailed description and examples.

1 is a schematic cross-sectional view of a ball-type carbonization furnace of Example 1. FIG. FIG. 3 is a schematic cross-sectional view of a ball-type carbonization furnace of Example 2. FIG. 4 is a schematic cross-sectional view of a ball type carbonization furnace of Example 3.

  The main features of the embodiments described below are listed. The technical elements described below are independent technical elements and exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Absent.

(Characteristic 1) In the radioactive waste volume reduction treatment device disclosed in this specification, one end of a pipe is located in the first powder storage unit, and the flow path cross-sectional area of one end of the pipe is equal to one end of the pipe. It may be smaller than the channel cross-sectional area of the first container at the height at which it is positioned. The exhaust gas discharged from the other end of the dry distillation section is sent to the first powder storage section. According to the feature 1, the flow rate of the exhaust gas flowing into one end of the pipe can be made larger than the flow rate of the exhaust gas flowing in the first container at a height at which one end of the pipe is located. For this reason, a relatively light weight residue (second residue) out of the residue discharged from the other end of the dry distillation portion by the exhaust gas flowing from the powder storage portion to the second container is transferred to the second container via the pipe. Can be transported. On the other hand, a relatively heavy residue (first residue) is stored in the first powder storage unit. According to this configuration, the residue can be classified using the fluid force of the exhaust gas. Moreover, the flow rate (namely, fluid force) of exhaust gas can be controlled by adjusting the flow path cross-sectional area of one end of piping, and the mass of the 2nd residue transferred to a 2nd container can be controlled.

(Characteristic 2) In the radioactive waste volume reducing device disclosed in the present specification, the radioactive waste supply means and the first superheated steam supply means are configured so that unreacted unreacted superheated steam is discharged from the dry distillation section. Alternatively, radioactive waste and superheated steam may be supplied to the dry distillation section. The dry distillation section may further discharge the radioactive waste and unreacted unreacted superheated steam from the other end of the superheated steam supplied to the dry distillation section. The unreacted superheated steam discharged from the other end of the dry distillation part may be supplied to the lower part of the second powder storage part via a pipe. A second residue is stored in a lower portion of the second powder storage unit. According to the feature 2, unreacted superheated steam decomposes the combustible matter in the second residue at the lower part of the second powder storage unit, and the volume of the second residue can be further reduced. Further, by using unreacted superheated steam, it is not necessary to separately supply superheated steam to the lower part of the second powder storage unit, and the apparatus configuration can be simplified. In addition, since the second residue has less mass variation than the conventional residue, the second residue can be efficiently decomposed.

(Feature 3) In the radioactive waste volume reduction treatment device disclosed in the present specification, the first container further includes a second superheated steam supply means for supplying superheated steam to the lower portion of the first powder storage unit. May be. A first residue is stored in a lower portion of the first powder storage unit. According to the feature 3, the superheated steam supplied by the second superheated steam supply means can decompose the combustible component in the first residue and further reduce the volume of the first residue in the lower part of the first powder storage unit. . In addition, since the first residue has less mass variation than the conventional residue, the first residue can be efficiently decomposed.

(Feature 4) In the radioactive waste volume reduction treatment device disclosed in the present specification, the carbonization section has a metal reaction vessel, and a plurality of ceramic or metal balls filled in the reaction vessel, You may have the stirring means which stirs these some ball | bowl. By using a ball-type dry distillation section, it is possible to efficiently perform thermal decomposition of the charged radioactive waste.

  With reference to FIG. 1, the ball-type dry distillation furnace 10 of Example 1 and the volume reduction processing method by the ball-type dry distillation furnace 10 will be described. The ball-type carbonization furnace 10 reduces the volume of used ion exchange resin having a relatively high level of radioactivity generated in a nuclear facility. The ball-type dry distillation furnace 10 includes a first container 12, a second container 14, and a pipe 16 that connects the first container 12 and the second container 14. The first container 12 is made of metal and has a cylindrical portion and a truncated cone portion connected to a lower portion of the cylindrical portion. The diameter of the cross section of the xy plane in the upper part of the truncated cone part (that is, the connection part with the cylindrical part) is substantially the same as the diameter of the cross section of the cylindrical part. The truncated cone portion has a shape in which the diameter of the cross section becomes smaller as it goes downward (−z direction). The second container 14 has substantially the same shape as the first container 12. The ball-type carbonization furnace 10 corresponds to an example of a “volume reduction treatment apparatus”.

  First, the first container 12 will be described. The first container 12 includes a carbonization unit 20, an external electric heater 28 that heats the carbonization unit 20 from the outside, an ion exchange resin supply nozzle 30 that supplies an ion exchange resin from the top of the carbonization unit 20, and the carbonization unit 20. A superheated steam supply nozzle 32 for supplying superheated steam from the upper side surface of the powder, a powder storage section 36 disposed below the dry distillation section 20, and a superheated steam supply nozzle for supplying superheated steam to the lower portion of the powder storage section 36. 38. The heater 28 corresponds to an example of “external heating means”, the ion exchange resin supply nozzle 30 corresponds to an example of “radioactive waste supply means”, and the superheated steam supply nozzle 32 corresponds to “first superheated steam supply means”. The powder reservoir 36 corresponds to an example of a “first powder reservoir”, and the superheated steam supply nozzle 38 corresponds to an example of a “second superheated steam supply unit”.

  The dry distillation section 20 includes a sealed reaction vessel 21, a plurality of ceramic balls 24 filled in the reaction vessel 21, a stirring blade 26 that stirs the ball 24, and a rotating shaft 22 that rotates the stirring blade 26. Have. The reaction vessel 21 has a cylindrical shape made of metal and includes a pressure control mechanism (not shown) that maintains the indoor pressure at −0.5 to −10 kPa. On the outer peripheral surface of the reaction vessel 21, heaters 28 are arranged at substantially equal intervals in the z direction. The heater 28 can control the temperature in the reaction vessel 21 to a desired temperature (about 400 to 700 ° C.). The length of the reaction vessel 21 in the z direction is appropriately determined according to the type of radioactive waste to be treated. The stirring blade 26 and the rotating shaft 22 correspond to an example of “stirring means”.

  A rotation shaft 22 is provided at the axial center of the reaction vessel 21. The rotating shaft 22 is rotated at a predetermined speed (about 0.1 to 2.0 rpm, preferably 0.5 rpm or more) by a drive motor (not shown). A spiral stirring blade 26 is attached to the periphery of the rotating shaft 22. The outer edge of the stirring blade 26 is positioned in the vicinity of the inner peripheral surface of the reaction vessel 21, and the inner edge is positioned with a space between the rotary shaft 22.

  As the ball 24 in the reaction vessel 21, a ceramic ball having a diameter of 10 to 25 mm and having corrosion resistance is used. However, the material of the ball 24 is not limited to this, and may be made of Hastelloy or Inconel, which is a high nickel alloy. By being agitated by the agitating blade 26, the ball 24 repeatedly descends and rises in the reaction vessel 21.

  An ion exchange resin supply nozzle 30 is installed on the upper surface of the reaction vessel 21. From the ion exchange resin supply nozzle 30, ion exchange resin generated in the nuclear facility is supplied into the reaction vessel 21. The ion exchange resin supplied into the reaction vessel 21 adheres to the surface of the ball 24 and moves inside the reaction vessel 21. For this reason, the residence time of the ion exchange resin in the reaction vessel 21 is the same as the descent time of the ball 24. On the other hand, a superheated steam supply nozzle 32 is installed on the side surface above the reaction vessel 21. Superheated steam is supplied from the superheated steam supply nozzle 32 to the ion exchange resin attached to the surface of the ball 24. As a result, the ion exchange resin and superheated steam react in the reaction vessel 21 to thermally decompose the ion exchange resin, and a residue and exhaust gas are generated. In the reaction vessel 21, the volume of the ion exchange resin is reduced to about 1/4.

  In general, the amount of superheated steam supplied from the superheated steam supply nozzle 32 is made larger than the amount of superheated steam that is theoretically required to thermally decompose the ion exchange resin supplied from the ion exchange resin supply nozzle 30. The This avoids incomplete thermal decomposition of the ion exchange resin due to insufficient supply of superheated steam. Therefore, a certain amount of superheated steam (hereinafter also referred to as “unreacted superheated steam”) that is not subjected to thermal decomposition of the ion exchange resin is generated in the reaction vessel 21.

  A holding plate 34 for holding the ball 24 in the reaction vessel 21 is disposed at the lower end of the reaction vessel 21. A powder reservoir 36 is provided below the holding plate 34. The holding plate 34 prohibits the passage of the ball 24 while allowing the passage of the residue, exhaust gas and unreacted superheated steam. This prevents the balls 24 filled in the reaction vessel 21 from falling into the powder storage unit 36, while the residue, exhaust gas, and unreacted superheated steam generated in the reaction vessel 21 are removed from the powder storage unit 36. Can be moved to.

  The residue generated by pyrolyzing the ion exchange resin is a powder mainly composed of iron oxide. There is some variation in the mass of the residue. Hereinafter, a relatively heavy residue among the residues is referred to as a heavy residue, and a relatively light residue (that is, a residue other than the heavy residue) is referred to as a light residue. From the lower end of the reaction vessel 21, the residue, exhaust gas and unreacted superheated steam are discharged to the powder reservoir 36 through the holding plate 34. Among these, heavy residues are stored in the powder storage unit 36 (described later). On the other hand, the light residue is transferred to the second container via the pipe 16 together with the exhaust gas and unreacted superheated steam (described later). The heavy residue corresponds to an example of “first residue”, and the light residue corresponds to an example of “second residue”.

  The lower part of the powder storage part 36 has a truncated cone shape, and an opening 42 that can be opened and closed is formed at the lower end thereof. The opening 42 is closed when the ion exchange resin is subjected to volume reduction processing in the ball-type carbonization furnace 10 and is opened when the volume reduction processing is not performed. When the opening 42 is opened, the residue can be discharged from the powder reservoir 36 to the outside. The angle formed by the wall surface of the truncated cone portion with the xy plane is equal to or greater than the repose angle of the heavy residue. For this reason, the heavy residue discharged from the lower end of the reaction vessel 21 slides on the wall surface of the truncated cone part and is stored in the lower part of the powder storage unit 36. Alternatively, the heavy residue falls to the lower part of the powder storage unit 36 as it is.

  A superheated steam supply nozzle 38 is provided below the powder reservoir 36. The superheated steam supplied from the superheated steam supply nozzle 38 into the powder reservoir 36 is used to thermally decompose the combustible component contained in the heavy residue.

  In addition, external electric heaters 40 are provided on the outer peripheral surface of the powder storage unit 36 at substantially equal intervals in the z direction. The temperature in the powder storage unit 36 is controlled by the heater 40 to a temperature (about 400 to 700 ° C.) at which the heavy residue can be thermally decomposed. The heavy residue further reduced in volume in the powder storage unit 36 is discharged from the opening 42 and sent to a solidification facility (not shown).

  Next, the second container 14 will be described. The second container 14 includes a filter unit 44, a powder storage unit 50, and an exhaust gas outlet 48. A sintered metal filter 46 is installed in the filter unit 44. An exhaust gas outlet 48 is installed on the side surface above the filter portion 44. The powder storage unit 50 is disposed below the filter unit 44. In addition, although the sintered metal filter was used in the present Example, it is not restricted to this, For example, you may use a ceramic filter. The powder storage unit 50 corresponds to an example of a “second powder storage unit”.

  From the 1st container 12, a light residue, waste gas, and unreacted superheated steam are sent to the 2nd container via piping 16 and nozzle 18 mentioned below. The lower part of the powder reservoir 50 has a truncated cone shape, and an opening 52 that can be opened and closed is formed at the lower end thereof. Similar to the opening 42, the opening 52 is closed when the ion exchange resin is subjected to volume reduction processing in the ball-type dry distillation furnace 10, and is opened when the volume reduction processing is not performed. When the opening 52 is opened, the residue can be discharged from the powder reservoir 50 to the outside. Similar to the powder reservoir 36, the angle formed by the wall surface of the truncated cone portion of the powder reservoir 50 and the xy plane is equal to or greater than the angle of repose of the light residue. For this reason, among the light residues discharged from the tip of the nozzle 18, a residue having a relatively large mass slides on the wall surface of the truncated cone portion and is stored in the lower part of the powder storage unit 50. Alternatively, it falls directly to the lower part of the powder storage unit 50. The exhaust gas outlet 48 is connected to an exhaust gas treatment device (not shown). The exhaust gas treatment device includes an exhaust gas blower. For this reason, the pressure in the vicinity of the exhaust gas outlet 48 is lower than the pressure in the powder reservoir 50 by the exhaust gas blower. Accordingly, the exhaust gas in the powder storage unit 50 moves up in the second container 14 and moves to the filter unit 44. The exhaust gas that has moved to the filter unit 44 is filtered by the sintered metal filter 46. The filtered exhaust gas is discharged from the exhaust gas outlet 48 and sent to the exhaust gas treatment device. Dust generated when the exhaust gas is filtered (that is, a residue having a relatively small mass among light residues) falls and is stored in the lower part of the powder storage unit 50.

  Next, the pipe 16 and the nozzle 18 will be described. The pipe 16 connects the first container 12 and the second container 14. Specifically, one end of the pipe 16 is connected to the upper part of the powder storage part 36 of the first container 12, and the other end of the pipe 16 is connected to the upper part of the powder storage part 50. By positioning one end of the pipe 16 at the upper part of the powder storage part 36, it is possible to prevent heavy residues accumulated in the lower part of the powder storage part 36 from entering the pipe 16. As is clear from FIG. 1, the cross-sectional area of the pipe 16 (the cross-sectional area of the yz plane) is the cross-sectional area of the inner peripheral surface of the first container 12 at the height at which one end of the pipe 16 is located ( It is smaller than the cross-sectional area of the xy plane (hereinafter, simply referred to as the flow path cross-sectional area of the powder reservoir 36).

  One end of a nozzle 18 is connected to the other end of the pipe 16. The nozzle 18 has a substantially L-shape, and the other end is located in a lower part of the powder reservoir 50. Thereby, the powder storage unit 36 and the powder storage unit 50 communicate with each other via the pipe 16 and the nozzle 18. The other end of the nozzle 18 is disposed at a position higher than the upper surface of the light residue (including dust) stored in the lower part of the powder storage unit 50. For this reason, it is prevented that the other end of the nozzle 18 contacts a light residue, and a light residue, exhaust gas, and unreacted superheated steam can be discharged | emitted from the nozzle 18 appropriately.

  Unreacted superheated steam is discharged from the nozzle 18. Unreacted superheated steam is used to thermally decompose combustible components contained in light residues (including dust) stored in the lower part of the powder storage unit 50. The light residue further reduced in the powder reservoir 50 is discharged from the opening 52 and sent to the solidification facility. The total of the heavy residue after volume reduction discharged from the opening 42 and the light residue after volume reduction discharged from the opening 52 is about 1/20 of the ion exchange resin supplied to the reaction vessel 21. The volume is reduced.

  Here, the flow of exhaust gas and unreacted superheated steam discharged from the lower end of the reaction vessel 21 to the powder reservoir 36 will be described. As described above, one end of the pipe 16 is connected to the upper part of the powder reservoir 36. The opening 42 at the lower end of the first container 12 is closed. For this reason, the exhaust gas and unreacted superheated steam that have flowed from the reaction vessel 21 to the powder reservoir 36 flow into the pipe 16 from the powder reservoir 36. At this time, since the flow passage cross-sectional area of the pipe 16 is smaller than the flow passage cross-sectional area of the powder reservoir 36, the flow rate of the exhaust gas flowing into one end of the pipe 16 and the unreacted superheated steam is higher. It becomes larger than the flow velocity of the exhaust gas and the unreacted superheated steam when flowing inside. Thereby, a relatively light residue (light residue) out of the exhaust gas discharged from the reaction vessel 21 to the powder reservoir 36 and the unreacted superheated steam is a flow of exhaust gas and unreacted superheated steam having a large flow rate. Then, it flows into the pipe 16 and is transferred to the powder reservoir 50 of the second container 14 via the pipe 16 and the nozzle 18. On the other hand, a relatively heavy residue (heavy residue) out of the residue discharged from the reaction vessel 21 falls into its own weight without flowing into the pipe 16 and is stored in the powder storage unit 36 below the reaction vessel 21. .

  Next, a method for reducing the volume of the ion exchange resin by the ball-type carbonization furnace 10 of this embodiment will be described. In the following, the flow of the ion exchange resin volume reduction process will be mainly described, and the detailed description of the same contents as those described above will be omitted.

(Ion exchange resin supply process, first superheated steam supply process, thermal decomposition process)
First, the ion exchange resin is supplied from the ion exchange resin supply nozzle 30 to the reaction vessel 21 of the first container 12 (ion exchange resin supply step), and superheated steam is supplied from the superheated steam supply nozzle 32 (first superheated steam supply). Process). The superheated steam is supplied more than the superheated steam required for the thermal decomposition of the ion exchange resin. The supply amount per unit time of the ion exchange resin and superheated steam is controlled by a control device (not shown). In the reaction vessel 21, the ion exchange resin is thermally decomposed by superheated steam and reduced in volume (thermal decomposition step). When the ion exchange resin is thermally decomposed, residue and exhaust gas are generated.

(First storage process, transfer process)
From the lower end of the reaction vessel 21, the residue, exhaust gas and unreacted superheated steam are discharged to the powder reservoir 36 through the opening of the holding plate 34. Among these, a relatively heavy residue (heavy residue) falls by its own weight and is stored in the lower part of the powder storage unit 36 (first storage step). On the other hand, a relatively light residue (light residue) is transferred to the powder reservoir 50 of the second container 14 via the pipe 16 and the nozzle 18 together with the exhaust gas and unreacted superheated steam (transfer process).

(Separation process, filtration process, second storage process)
From the light residue, exhaust gas, and unreacted superheated steam transferred to the powder storage unit 50, a residue having a relatively large mass is separated from the light residue by gravity or the like (separation step). The separated residue falls and is stored in the powder storage unit 50 (second storage step). On the other hand, the exhaust gas from which a part of the residue is separated rises in the second container 14 and is filtered by the sintered metal filter 46 in the filter unit 44 (filtering step). The filtered exhaust gas is sent from the exhaust gas outlet 48 to the exhaust gas treatment device. The dust removed from the exhaust gas in the filtration step falls from the sintered metal filter 46 and is stored in the powder storage unit 50 by performing a backwash process or the like (second storage step).

(Unreacted superheated steam supply process, light residue pyrolysis process)
The unreacted superheated steam that has not reacted with the ion exchange resin in the reaction vessel 21 is supplied to the lower part of the powder reservoir 50 via the pipe 16 and the nozzle 18 (unreacted superheated steam supply process). The combustible component contained in the light residue stored in the powder storage unit 50 in the second storage step is pyrolyzed by unreacted superheated steam and further reduced in volume (light residue pyrolysis step). The light residue after pyrolysis is discharged from the opening 52 of the powder reservoir 50 and sent to the solidification facility.

(Second superheated steam supply process, heavy residue pyrolysis process)
Superheated steam is supplied from the superheated steam supply nozzle 38 to the lower part of the powder reservoir 36 of the first container (second superheated steam supply process). The combustible component contained in the heavy residue stored in the powder storage unit 36 in the first storage step is thermally decomposed and further reduced by this superheated steam (heavy residue thermal decomposition step). The heavy residue after pyrolysis is discharged from the opening 42 of the powder reservoir 36 and sent to the solidification facility.

  The effects of the ball-type dry distillation furnace 10 and the volume reduction processing method using the ball-type dry distillation furnace 10 according to the first embodiment will be described. The ball-type dry distillation furnace 10 has a configuration in which two separately formed containers (first container 12 and second container 14) are connected by a pipe 16. For this reason, by adjusting the length of the pipe 16, the two containers 12, 14 can be arranged at a desired distance apart. Further, the size of the containers 12 and 14 alone can be reduced as compared with a conventional ball-type dry distillation furnace in which the carbonization unit, the filter unit, and the powder storage unit are integrally formed. In particular, since the diameter of the cross-section of the powder reservoirs 36 and 50 in the xy plane is smaller than the diameter of the powder reservoir of the conventional ball type dry distillation furnace, the height of the truncated cone portion of the powder reservoirs 36 and 50 is high. Can be shortened compared to the conventional case. Thereby, the height of the containers 12 and 14 (that is, the height of the ball-type dry distillation furnace 10) can be reduced. Therefore, the containers 12 and 14 can be installed in a relatively narrow space that could not be installed conventionally. For this reason, the freedom degree of the installation location which installs the ball-type dry distillation furnace 10 can be improved.

  In particular, the ball-type carbonization furnace 10 of this embodiment performs a volume reduction treatment on an ion exchange resin having a relatively high radioactivity level. For this reason, the ball-type carbonization furnace 10 is installed in a room called a cell covered with a thick concrete wall for shielding radiation. According to the configuration of the ball type dry distillation furnace 10 of the present embodiment, even when the height of the existing cell to the ceiling is low, the height of the containers 12 and 14 can be suppressed, and these can be installed in the existing cell. . Thereby, the ball-type dry distillation furnace 10 can be appropriately installed in the existing cell without newly recreating the cell. In addition, when the containers 12 and 14 are installed in separate cells, the piping 16 penetrates the concrete wall and connects the containers 12 and 14. At this time, it is preferable that the portion of the piping 16 exposed to the outside of the cell is covered with a radiation shielding member.

  When the ball-type carbonization furnace 10 is installed in the cell, maintenance is performed from outside the cell using a remote operation jig such as a power manipulator or a master-slave manipulator. According to the present embodiment, since the first container 12 and the second container 14 can be arranged apart from each other, it is easy to operate the remote operation jig and the work efficiency is improved. In addition, by separating the first container 12 and the second container 14, the shape of each container becomes simpler than the conventional one. For this reason, the accessibility to each container improves and it becomes easy to maintain.

  Furthermore, in the present embodiment, utilizing the phenomenon that the flow rate increases when exhaust gas generated by the thermal decomposition of the ion exchange resin flows into the pipe 16, the residue generated by the thermal decomposition of the ion exchange resin is classified into a heavy residue and a light residue. To do. Since the residue is mainly composed of iron oxide, the density is substantially the same. For this reason, there is a correlation between the mass of the residue and the particle size, and the particle size of the light residue is smaller than the particle size of the heavy residue. Therefore, when comparing a light residue and a heavy residue with the same mass, the total surface area of the light residues is larger than the total surface area of the heavy residues. For this reason, the light residue has a larger contact surface with the superheated steam, and the combustible component in the light residue reacts faster with the superheated steam than the combustible component in the heavy residue. By classifying the residue in this way, the amount of superheated steam to be supplied can be adjusted according to the particle size. When the residue is stored in the powder storage part regardless of the size of the mass (that is, regardless of the particle size) as in the past, if the superheated steam is efficiently applied to the surface of the residue because of a large variation in the particle size. There was nothing. For this reason, it has been necessary to supply more superheated steam than the theoretically required superheated steam. According to the present embodiment, by classifying the residue according to the particle size, the variation in the particle size of the residue stored in each powder storage unit 36, 50 is reduced. For this reason, in each powder storage part 36 and 50, superheated steam can be efficiently applied to the surface of a residue, and a residue can be thermally decomposed more efficiently than before. Moreover, the reaction rate of the combustible part in a heavy residue is slower than the reaction rate of the combustible part in a light residue. For this reason, the supply rate of the superheated steam supplied to the powder storage part 36 can be reduced compared with the past. By classifying the residue, the supply rate of superheated steam can be controlled to an amount commensurate with the reaction rate of the combustible component in the residue, and it is not necessary to supply superheated steam excessively. In particular, when the heavy residue and the light residue have the same mass, the light residue has a larger total surface area and the reactivity with superheated steam is improved. For this reason, the amount of superheated steam supplied to the light residue can be made smaller than the amount of superheated steam supplied to the heavy residue having the same mass. Therefore, the amount of superheated steam supplied to the light residue can be made closer to the theoretically required amount of superheated steam. As a result, the amount of superheated steam necessary for thermally decomposing the residue can be reduced by about 5 to 10% as compared with the conventional ball-type carbonization furnace. Since the variation in the particle size can be reduced and an appropriate amount of superheated steam can be supplied according to the particle size, the residue can be efficiently pyrolyzed and the amount of superheated steam can be reduced. That is, the residue can be reduced in volume with a small amount of superheated steam in a shorter time than in the past. In addition, since the amount of superheated steam can be reduced, the exhaust gas treatment facility installed downstream of the second container 14 can be downsized.

  In the present embodiment, the light residue in the powder reservoir 50 is pyrolyzed using unreacted superheated steam that has not been used for the thermal decomposition of the ion exchange resin in the reaction vessel 21. For this reason, it is not necessary to separately supply superheated steam to the powder storage unit 50. Even if the container is divided into two and the powder storage portions 36 and 50 are provided respectively, the superheated steam supply nozzle may not be installed in the second container 14. Moreover, since unreacted superheated steam is supplied to the lower part of the powder storage part 50, it is easy to contact a light residue. For this reason, a light residue can fully be made to react with unreacted superheated steam, and a light residue can be thermally decomposed appropriately.

  Further, by adjusting the cross-sectional area of the pipe 16, the flow rate of the exhaust gas and unreacted superheated steam flowing into the pipe 16 can be controlled, the residue falling on the powder storage unit 36, and the powder storage unit 50. The mass ratio of the residue transferred to can be controlled. This also makes it possible to thermally decompose the residue more efficiently.

  Next, Example 2 will be described with reference to FIG. Hereinafter, only differences from the first embodiment will be described, and detailed description of the same configurations as those of the first embodiment will be omitted. The same applies to other embodiments.

  In the ball-type dry distillation furnace 110 according to the second embodiment, the first container 12 and the second container 14 are connected by a pipe 116. The pipe 116 includes a pipe 116a extending in the x direction, a pipe 116b extending in the z direction, and a pipe 116c extending in the x direction. One end of the pipe 116a is located above the powder reservoir 36, and the other end is connected to one end of the pipe 116b. One end of the pipe 116 c is connected to the other end of the pipe 116 b, and the other end is located below the powder storage unit 50. The light residue discharged from the lower end of the reaction vessel 21 to the powder storage unit 36 is supplied to the lower part of the powder storage unit 50 via the pipe 116 together with the exhaust gas and unreacted superheated steam. For this reason, unreacted superheated steam can be supplied to the lower part of the powder storage part 50 without using the nozzle 18, and the light residue stored at the lower part of the powder storage part 50 can be thermally decomposed appropriately. . Also with this configuration, the same effects as the ball-type dry distillation furnace 10 of Example 1 can be obtained. The other end of the pipe 116 is preferably located at a position higher than the upper surface of the light residue stored in the powder storage unit 50. The amount of light residue stored in the powder storage unit 50 is smaller than the amount of heavy residue stored in the powder storage unit 36. For this reason, even if the other end of the pipe 116 is connected to the lower part of the powder reservoir 50, the other end of the pipe 116 can be kept at a position higher than the upper surface of the light residue.

  The ball-type dry distillation furnace 210 according to the third embodiment is configured so that the lower part of the powder storage unit 50 of the second container 14 has substantially the same height as the upper part of the powder storage part 36 of the first container 12. The container 14 is disposed at a high position with respect to the first container 12. The upper part of the powder storage part 36 of the first container 12 and the lower part of the powder storage part 50 of the second container 14 are connected using a pipe 216 extending in the x direction (horizontal direction). Also with this configuration, the same effects as the ball-type dry distillation furnace 10 of Example 1 can be obtained. Further, since the pipe 216 is not bent, the light residue is appropriately transferred to the powder storage unit 50 without staying in a bent part of the pipe.

  As mentioned above, although the Example of the technique which this specification discloses was described in detail, these are only illustrations, The volume reduction processing apparatus and volume reduction processing method of a radioactive waste which this specification discloses are said implementation. Various modifications and changes to the examples are included. For example, in the above embodiment, the ball type carbonization furnace is used, but the type of the carbonization furnace is not limited to this, and for example, an induction heating type carbonization furnace may be used. Further, the radioactive waste to be volume-reduced is not limited to the ion exchange resin, and for example, a radioactive waste solvent generated in a nuclear facility (for example, a waste solvent in a fuel reprocessing plant) may be volume-reduced. The superheated steam supply nozzle 32 may be installed on the upper surface of the first container 12. Similarly, the exhaust gas outlet 48 may be installed on the upper surface of the second container 14.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

DESCRIPTION OF SYMBOLS 10: Ball-type carbonization furnace 12: 1st container 14: 2nd container 16: Piping 18: Nozzle 20: Carbonization part 21: Reaction container 22: Rotating shaft 24: Ball 26: Stirring blade 28: Heater 30: Ion exchange resin supply Nozzle 32: Superheated steam supply nozzle 36: Powder storage unit 38: Superheated steam supply nozzle 44: Filter unit 50: Powder storage unit

Claims (5)

A first container;
A second container;
A pipe connecting the first container and the second container,
The first container
A dry distillation section;
An external heating means for heating the dry distillation section from the outside;
A radioactive waste supply means for supplying radioactive waste to one end of the dry distillation section;
First superheated steam supply means for supplying superheated steam to the dry distillation section;
A first powder storage unit disposed at the other end of the carbonization unit,
The dry distillation section discharges residue and exhaust gas generated by pyrolyzing radioactive waste from the other end,
The first residue which is a part of the residue discharged from the other end of the dry distillation part is stored in the first powder storage part,
The remainder of the residue discharged from the other end of the dry distillation section, the second residue having a mass smaller than that of the first residue is supplied to the second container through the pipe together with the exhaust gas,
The second container
A filter unit for filtering the exhaust gas supplied from the piping;
A second powder storage part that is disposed at one end of the filter part and stores the second residue supplied from the pipe;
One end of the pipe is located in the first powder reservoir ,
The other end of the pipe is located in the second powder reservoir,
A volume reduction processing apparatus for radioactive waste, wherein a flow path cross-sectional area at one end of a pipe is smaller than a flow path cross-sectional area of a first container at a height at which one end of the pipe is located. The radioactive waste supply means and the first superheated steam supply means supply the radioactive waste and superheated steam to the dry distillation section so that unreacted unreacted superheated steam is discharged from the dry distillation section,
The dry distillation part further discharges radioactive waste and unreacted unreacted superheated steam from the other end of the superheated steam supplied to the dry distillation part,
The volume reduction of the radioactive waste according to claim 1, wherein unreacted superheated steam discharged from the other end of the dry distillation part is supplied to a lower part of the second powder storage part via a pipe. Processing equipment.   3. The radioactive waste volume reduction processing apparatus according to claim 1, wherein the first container further includes second superheated steam supply means for supplying superheated steam to a lower portion of the first powder storage unit. .   The carbonization section has a metal reaction vessel, a plurality of ceramic or metal balls filled in the reaction vessel, and a stirring means for stirring the plurality of balls. The volume reduction processing apparatus of the radioactive waste as described in any one of -3. A first container;
A second container;
A pipe connecting the first container and the second container,
The first container
A dry distillation section;
A first powder storage unit disposed at the other end of the carbonization unit,
The second container
A filter unit for filtering the exhaust gas supplied from the piping;
A second powder storage part disposed at one end of the filter part,
One end of the pipe is located in the first powder reservoir ,
The other end of the pipe is located in the second powder reservoir,
The volume of radioactive waste is reduced by using a radioactive waste volume reduction treatment device in which the flow path cross-sectional area at one end of the pipe is smaller than the flow path cross-sectional area of the first container at the height at which one end of the pipe is located. Is a way to handle
A pyrolysis step of pyrolyzing the radioactive waste with superheated steam in the dry distillation section;
A first storage step of transferring and storing a first residue, which is part of the residue generated by the pyrolysis step, from the dry distillation section to the first powder storage section;
A transfer step of transferring a second residue, which is a residue of the residue generated by the pyrolysis step, having a mass smaller than that of the first residue to the second powder storage unit via the pipe together with the exhaust gas generated by the pyrolysis step; ,
A filtration step of transferring the exhaust gas transferred to the second powder storage unit to the filter unit and filtering the exhaust gas;
A second storage step of storing the second residue transferred to the second powder storage unit in the second powder storage unit,
In the transfer step, the second residue is transferred to the second powder reservoir by exhaust gas.

Images