JP2015017816A - Underwater suspended matter collection device and underwater suspended matter collection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underwater suspended matter collection device capable of further improving a collection rate of underwater suspended matters suspended in water.SOLUTION: An underwater suspended matter collection device 1 has a supporting member 2 where a pre-separator 4, a pump 13, a post-separator 14 and a filter device 16 are fixed thereto and a suction nozzle 3 which is connected to the pre-separator 4 through a hose 17. The pre-separator 4, the pump 13, the post-separator 14 and the filter device 16 are connected in this order. A partition plate is installed inside the pre-separator 4 and forms a downward region and an upward region inside the same. The downward region and the upward region are connected to each other at a lower edge section of the pre-separator 4. A ratio L'/L of a length L' of the partition plate in an axial direction of the pre-separator 4 to a height L of a cylindrical section is within a range of 0.4 to 0.8. Thus, the underwater suspended matter collection device 1 separates a concrete fragment 36, a suspended matter sucked through the suction nozzle 3, in the downward region of the pre-separator 4 due to gravitational deposition and thereby improving a collection rate of the suspended matter.

Description

  The present invention relates to an underwater suspended matter collection device, and more particularly to an underwater suspended matter collection device suitable for application to a technique suitable for application to maintenance work of a nuclear power plant.

  Maintenance inspection of the boiling water nuclear power plant is performed after the operation of the boiling water nuclear power plant is stopped. At the time of this maintenance and inspection, the fuel storage pool, the equipment temporary storage pool, the reactor pressure vessel from which the top cover was removed, and the reactor formed directly above the reactor pressure vessel and above the reactor containment vessel Each well is filled with water. In boiling water nuclear power plants, underwater work is generally performed remotely.

  For this reason, for example, when replacing the in-reactor structure installed in the reactor pressure vessel with a new in-reactor structure composed of new materials, or when disposing of the in-reactor structure after the end of its useful life In this case, the radioactive cladding adhering to the existing in-furnace structure, and the cutting powder generated in the cutting work accompanying the replacement and dismantling of the in-furnace structure are scattered in the water. Moreover, when a part of concrete which is a structural material of a reactor building is missing, there is a possibility that concrete powder and crushed pieces may be mixed into the water in the pool. Furthermore, fuel fragments loaded into the reactor core in the reactor pressure vessel due to the case where the fragments mixed in the fuel storage pool break the spent fuel assembly stored in the fuel storage pool, or due to severe accidents, etc. In the case where a part of the body is dissolved, the mixed powder of uranium and zirconium contained in the fuel assembly may be deposited or scattered in the water.

  These underwater suspended solids and deposits not only cause a loss of visibility when performing underwater work, but if the underwater suspended solids contain nuclear fuel, control and recovery after collection of underwater suspended solids It is necessary to prepare a storage method. Although it is possible to hold a crushed piece having a large size, workability deteriorates when a crushed piece having a size such as gravel of about several tens of mm is grasped. However, a method for recovering the suspended matter in water from several μm to about 30 mm floating in water with high efficiency has not been clarified.

  When applying a method that spreads flocculant in water and makes it easier to settle by increasing the size of suspended matter in water, the dispersed flocculant itself becomes radioactive waste, resulting in an increase in the amount of radioactive waste Will do. In addition, the work space is reduced when applying a method of slowing the recovery flow rate of water containing suspended solids or a method of enlarging the sedimentation vessel used to recover suspended solids in order to improve recovery performance. Work efficiency will decrease. In addition, when the suspended matter in water is collected, the radiation amount of the collecting device itself increases, so that the operator cannot perform maintenance if the device is installed in the air.

  WO 91 / 011392A describes a method for purifying sewage. In this purification method, the process of mixing the flocculant in the sewage and causing the inorganic and organic substances contained in the sewage to float and settle is repeated a plurality of times.

  Japanese Patent Laid-Open No. 2007-24586 discloses that an in-reactor structure taken out from a reactor pressure vessel is placed in the water of an equipment temporary storage pool, and high-pressure water containing a cutting aid (for example, alumina powder) is injected from a cutting nozzle. An abrasive water jet cutting method for cutting a furnace internal structure is described. In this abrasive water jet cutting method, the cutting aid sprayed from the cutting nozzle and the cutting powder of the in-furnace structure are collected by the collector. The cutting aid and cutting powder collected by the collector are sequentially separated by a steam separator, a centrifuge and a filter and collected in a collection container.

  JP-A-2007-303942 discloses that, as in JP-A-2007-24586, high-pressure water containing a cutting aid is jetted from a cutting nozzle to cut the internal structure in the water of the equipment temporary storage pool. It is described. The cutting aid used for cutting and the cutting powder of the in-furnace structure are separated from water by a multistage cyclone separator and collected in a collection container.

WO91 / 011392A JP 2007-24586 A JP 2007-303942 A

  The pool of a boiling water nuclear power plant has a water depth of about 10 m to 30 m. When the water is stationary for a long period of time, the suspended matter in the water is accumulated on the inner surface of the pool and the surface of the equipment in the water. It will float in the water. In particular, when a suspended matter of several μm floats in water, the visibility from the water surface to the pool bottom is extremely deteriorated as the water depth increases even if the suspended matter suspended in water has a slight concentration.

  For this reason, micron-sized suspended matter floating in the water from gravel-sized pieces of concrete that have accumulated near the bottom of the pool can be once-through as much as possible, and the size identified as a waste container (diameter 1 m or less) It is important to collect using the container of In particular, it is desired to improve the recovery efficiency of suspended matters in water.

  An object of the present invention is to provide an underwater suspended matter recovery apparatus that can further improve the recovery efficiency of underwater suspended matters floating in water.

  A feature of the present invention that achieves the above-described object is that a support member and a separation plate that is attached to the support member and has a partition plate provided therein to form a descending region and an ascending flow region whose lower end portions are in communication with each other A suction nozzle connected to the separation device and connected to the lowering region; a suction pump attached to the support member and connected to the lifting device; and supported by the support member; A recovery container connected to the lower end and communicated with the descending region, the ratio L ′ / L of the length L ′ of the support plate to the height L of the separator in the axial direction is 0.4 to It exists in the range of 0.8.

  Since the ratio L ′ / L of the length L ′ of the support plate to the height L of the separation device in the axial direction of the separation device is in the range of 0.4 to 0.8, it is sucked together with water by the suction nozzle. In addition, the separation efficiency of insoluble components that are suspended in water that has reached the descending region of the separation device is improved, and the recovery efficiency of suspended matter in water is further improved.

  According to the present invention, the separation efficiency of insoluble components that are suspended in water can be improved, and the recovery efficiency of suspended matter in water can be further improved.

It is explanatory drawing of the underwater suspended solid collection method of Example 1 which is one suitable Example of this invention. 1 is an enlarged longitudinal sectional view of an underwater suspended matter collection device used in Example 1. FIG. FIG. 3 is an enlarged longitudinal sectional view of the front separator shown in FIG. 2. It is explanatory drawing which shows the part performance of the suspended matter in a water in a front | former stage separator, and shows the change of ratio of the collection | recovery amount with respect to the collection | recovery amount with respect to partition plate length L '/ height of the front | former stage separator. It is explanatory drawing of the underwater suspended solid collection method of Example 2 which is another suitable Example of this invention. It is a longitudinal cross-sectional view of the underwater suspended matter collection | recovery apparatus used for the underwater suspended matter collection method of Example 3 which is another suitable Example of this invention. It is explanatory drawing of the underwater suspended solid collection method of Example 4 which is another suitable Example of this invention. It is VIII-VIII sectional drawing of FIG. It is explanatory drawing of the underwater suspended solid collection | recovery method of Example 5 which is another suitable Example of this invention. It is XX sectional drawing of FIG.

  Examples of the present invention will be described below.

  The underwater suspended matter collection method of Example 1, which is a preferred embodiment of the present invention, will be described with reference to FIGS. The underwater suspended matter collection method of this embodiment is an example applied to a fuel storage pool of a boiling water nuclear power plant.

  First, the underwater suspended solids recovery apparatus 1 used in this embodiment will be described with reference to FIGS. The underwater suspended matter collection device 1 includes a support member 2, a suction nozzle 3, a front separator 4, recovery containers 12 and 15, a pump (suction pump) 13, a rear separator 14, a filter device 16, thermometers 24A and 24B, a dose. A total 25 and a display device 26 are provided.

  The front-stage separator 4, the pump 13, the collection containers 12 and 15, the rear-stage separator 14, the filter device 16, and the thermometers 24 </ b> A and 24 </ b> B are attached to the support member 2. The front separator 4, the pump 13, the rear separator 14, the filter device 16, and the collection containers 12 and 15 are attached to the support member 2 that is a rectangular parallelepiped having an internal space. The front separator 4, the pump 13, the rear separator 14, and the filter device 16 are installed on the upper surface of the upper member 10 of the support member 2. The collection containers 12 and 15 are disposed in the internal space of the support member 2 formed below the upper member 10 and are installed in the support member 2. The recovery container 12 is positioned directly below the front-stage separator 4, and the recovery container 15 is positioned directly below the rear-stage separator 14.

  As shown in FIG. 3, the front separator 4 includes a cylindrical portion 6, a bottom portion 7, and a partition plate 8. The bottom portion 7 is an inverted conical cylindrical portion having a region 10 formed therein, and is attached to the lower end of the cylindrical portion 6. The bottom portion 7 has an inclined surface that is inclined inwardly downward. The upper end of the cylindrical portion 6 is sealed by the lid portion 5.

  The partition plate 8 is attached to the lower surface of the lid portion 5 and is disposed in the cylindrical portion 6. The partition plate 8 passes through the center of the cylindrical portion 6 in the radial direction of the front separator 4, and one end of the partition plate 8 in the radial direction is welded to the inner surface of the cylindrical portion 6. The other end of the partition plate 8 in the radial direction is welded to the inner surface of the cylindrical portion 6 at a position 180 ° opposite to the position where the one end of the partition plate 8 is welded to the inner surface of the cylindrical portion 6. . One end and the other end of the partition plate 8 are welded to the inner surface of the cylindrical portion 6 over the entire length of the partition plate 8 in the axial direction of the front separator 4. Such a partition plate 8 divides the inside of the cylindrical portion 6 into a descending region 9A and an ascending region 9B. The descending region 9 </ b> A and the ascending region 9 </ b> B are respectively connected to the region 10 formed in the bottom 7.

  A flexible hose 17 connected to the suction nozzle 3 is connected to the cylindrical portion 6 and communicated with the descending region 9A. A recovered material discharge pipe 22 connected to the lower end of the bottom 7 of the front separator 4 is detachably connected to a recovery container 12 disposed in the support member 2. A transfer pipe 18 connected to the cylindrical portion 6 and connected to the ascending region 9 </ b> B is connected to the pump 13. A transfer pipe 19 connects the pump 13 and the rear separator 5. For example, a cyclonic separator is used as the rear separator 5. A recovered product discharge pipe 23 connected to the bottom of the rear separator 5 is detachably connected to a recovery container 15 disposed in the support member 2. The rear separator 5 is further connected to the filter device 16 by a transfer pipe 20. The filter device 16 has a filter paper or a filter cloth as a filter medium disposed in a container. A drain pipe 21 is connected to the filter device 16.

  The inlet formed in the cylindrical portion 6 and connected to the hose 17 and the inlet formed in the cylindrical portion 6 in communication with the transfer pipe 18 are opposed to the partition plate 8 disposed in the cylindrical portion 6. .

  Thermometers 24 </ b> A and 24 </ b> B are attached to the support member 2 and disposed in the internal space of the support member 2. The thermometer 24 </ b> A is disposed near the collection container 12 and measures the surface temperature of the collection container 12. The thermometer 24 </ b> B is disposed near the collection container 15 and measures the surface temperature of the collection container 15. The thermometers 24A and 24B are connected to the display device 26 by wiring 39.

  In the underwater suspended matter collection method of the present embodiment, the concrete fragments 36 accumulated in the fuel storage pool 30 of the boiling water nuclear power plant are sucked using the underwater suspended matter collection device 1. The fuel storage pool 30 is formed by being surrounded by an operation floor in a reactor building (not shown) of a boiling water nuclear power plant. Cooling water 38 is filled in the fuel storage pool 30. A plurality of spent fuel storage containers 35 in which a plurality of spent fuel assemblies are stored are placed at the bottom of the fuel storage pool 30 and stored in the cooling water 38. Concrete fragments 36 are deposited on the upper surfaces of these spent fuel storage containers 35.

  A work carriage 31 is disposed across the fuel storage pool 30 and is movably installed on the operation floor. A fuel exchanger moving on the operation floor may be used as the work carriage 31. The support member 2 of the underwater suspended matter collection device 1 is suspended from a crane 32 attached to the work carriage 31 so as to be able to traverse, and is lowered into the cooling water 38 of the fuel storage pool 30, and is placed in a predetermined position in the cooling water 38. Retained. A scale 37 is provided on the crane 32, and the display device 26 is placed on the work carriage 31. The scale 37 is connected to the display device 26 by a wiring 41. The dosimeter 25 is suspended from the work carriage 31 and is disposed in the vicinity of the support member 2 in the cooling water 38. The dosimeter 25 is connected to the display device 26 by wiring 40. Note that the two dosimeters 25 may be separately disposed facing the collection containers 12 and 15 and installed on the support member 2. An underwater camera 27 for monitoring is disposed in the cooling water 38 and is suspended from the work carriage 31. The illumination 28 is suspended from the work carriage 31 and disposed in the cooling water 38. The suction nozzle 3 is attached to the lower end of a pole 33 held by an operator on the work carriage 31. The suction nozzle 3 is also disposed in the cooling water 38 in the fuel storage pool 30.

  The underwater suspended matter collection method of this embodiment is started by driving the pump 13. The operator cannot see the bottom of the fuel storage pool 30 from the work cart 31. For this reason, an image captured by the underwater camera 27 is displayed on the display device 26 while illuminating the inside of the fuel storage pool 30 with the illumination 28, and the operator views the image in the state of the cooling water 38 in the fuel storage pool 30. That is, the position where the spent fuel storage container 35 and the concrete fragment (insoluble component) 36 exist can be confirmed. While viewing this image, the operator on the work carriage 31 operates the pole 33 to lower the suction nozzle 3 to the vicinity of the upper surface of the spent fuel storage container 35 stored in the fuel storage pool 30. Thereafter, when the pump 13 is driven, the concrete fragments 36 accumulated on the upper surface of the spent fuel storage container 35 are sucked into the suction nozzle 3 together with the surrounding cooling water 38.

  The concrete crushed pieces 36 sucked by the suction nozzle 3 are guided into the descending region 9A from the inlet of the front separator 4 through the hose 17 together with the sucked cooling water 38. The sucked cooling water 38 descends in the descending region 9A, rises in the ascending region 9B through the region 10 in the bottom portion 7, and is discharged to the transfer pipe 18. The flow rate of the cooling water 38 descending in the descending region 9A becomes slow, and the concrete fragment 36 having a particle size of 1 mm or more contained in the cooling water 38 is separated from the cooling water 38 by gravity settling in the descending region 9A. Then, it is discharged from the region 10 in the bottom 7 into the recovered material discharge pipe 22. Since the inclined surface of the bottom portion 7 is inclined at an angle of 45 ° with respect to a horizontal plane perpendicular to the central axis of the front separator 4, the concrete fragments 36 separated by gravity sedimentation follow the inner surface of the bottom portion 7. It is easy to be discharged into the recovered material discharge pipe 22. The separated concrete fragments 36 are collected in the collection container 12 through the collected material discharge pipe 22. The flow rate of the cooling water 38 that descends in the descending region 9 </ b> A decreases to 1/10 of the flow rate of the cooling water 38 that flows in the hose 17. For this reason, while the cooling water 38 descends in the descending region 9A, gravity sedimentation of the concrete crushed pieces 36 contained in the cooling water 38 is promoted, and the separation efficiency of the concrete crushed pieces 36 from the cooling water 38 is increased. improves.

  The solid separation performance by the pre-stage separator will be described. Inventors performed the test which confirms the separation performance of the concrete crushed piece contained in water using the front | former stage separator 4 which installed the partition plate 8 inside. The pre-stage separator 4 used has the structure shown in FIG. Five kinds of partition plates 8 having different lengths L ′ in the axial direction of the front separator 4 are separately arranged in the cylindrical portion 6 of the front separator 4, and the separation performance of the concrete fragments is confirmed in each case. did. Since the height L of the cylindrical portion 6 of the front separator 4 is not changed, the height L ′ of the partition plate 8 with respect to the height of the front separator 4, that is, the height L of the cylindrical portion 6 in the above five cases. The ratios L ′ / L are different as shown in FIG. In this test, the ratio L ′ / L is changed in five steps from 0.3 to 1.0.

  Water containing simulated concrete fragments having different particle diameters was supplied to the descending region 9A of the front separator 4, and the separation state of the concrete fragments contained in water in the front separator 4 was confirmed. This test yielded the separation performance results shown in FIG. FIG. 4 shows a change in the ratio B / A of the recovered amount B of the concrete fragment to the suction amount A of the concrete fragment with respect to the ratio L ′ / L. According to the test results shown in FIG. 4, by setting the ratio L ′ / L within the range of 0.4 to 0.8, the ratio B / A, that is, the amount of recovered concrete fragments is increased. Preferably, the ratio L ′ / L is set in the range of 0.5 to 0.6. By setting the ratio L ′ / L within the range of 0.5 to 0.6, the ratio B / A is maximized. In the present embodiment, the ratio L ′ / L is, for example, 0.6 in the upstream separator 4.

  By using the pre-stage separator 4, a concrete crushed piece having a size of several tens of mm can be efficiently separated from the cooling water 38 and collected in the collection container 12.

  The concrete fragment 36 having a size of less than 1 mm that has not been separated by the pre-separator 4 rises in the ascending region 9B and is discharged from the discharge port of the cylindrical portion 6 to the transfer pipe 18. The cooling water 38 including the concrete crushed pieces 36 is increased in pressure by the pump 13 and guided into the rear separator 14 through the transfer pipe 19. Since the particle size of the concrete fragment 36 discharged to the transfer pipe 18 is less than 1 mm, the pump 13 is not damaged by the concrete fragment 36. The post-stage separator 14 is a cyclonic separator, and the cooling water 38 including the concrete fragment 36 that has flowed into the post-stage separator 14 swirls in the post-stage separator 14. Due to the turning of the cooling water 38, centrifugal force acts on the concrete crush pieces 36 of less than 1 mm contained in the cooling water 38. For this reason, the concrete fragment 36 is separated from the cooling water 38 in the post-separator 14 and is collected in the collection container 15 through the collected material discharge pipe 23.

  The cooling water 38 discharged from the rear separator 14 to the transfer pipe 20 is guided to the filter device 16. Fine concrete fragments 36 that have not been separated by the post-separator 14 flow into the filter device 16 together with the cooling water 38 and are removed by the filter device 16. The cooling water 38 that passes through the filter device 16 and contains almost no concrete fragments 36 is discharged through the drain pipe 21 into the cooling water 38 in the fuel storage pool 30.

  An operator on the work carriage 31 can suck the concrete fragments 36 accumulated on the spent fuel storage container 35 at different positions by the suction nozzle 3 by moving the pole 33 in the horizontal direction. As described above, the sucked concrete fragment 36 is removed by the front separator 4, the rear separator 14, and the filter device 16 according to the size. By moving the pole 33 in the horizontal direction, the concrete fragments 36 accumulated on each spent fuel storage container 35 stored in the fuel storage pool 30 can be sucked and recovered in the recovery containers 12 and 15. it can. Solid matter which is a floating matter floating in the cooling water 38 in the fuel storage pool 30 is also sucked by the suction nozzle 3 and removed from the cooling water 38 by each separator described above.

  The underwater suspended matter collection device 1 used in the present embodiment arranges a partition plate 8 having a ratio L ′ / L of 0.6 in the front separator 4, and a descending region 9 </ b> A and a rising region in the front separator 4. Since 9B is formed, the separation efficiency of the concrete crushed pieces 36 that are insoluble components from the cooling water 38 including the concrete crushed pieces 36 supplied from the suction nozzle 3 to the upstream separator 4 is improved.

  The amount of the concrete crushed pieces 36 separated by the front-stage separator 4 and the rear-stage separator 14 and collected in the collection containers 12 and 15 respectively increases, and the concrete crushed pieces from which the collection container 12 or the collection container 15 is collected. 36 could be full. In this case, the crane 32 is operated and the underwater suspended matter collection device 1 suspended from the crane 32 is lifted from the fuel storage pool 30 and filled with the concrete fragment 36, for example, the collection vessel 12. Needs to be replaced with an empty new collection container 12.

  A measuring instrument 37 attached to the crane 32 measures the weight of the suspended underwater collection device 1. The measured weight is displayed on the display device 26. When the weight of the underwater suspended matter collection device 1 displayed on the display device 26 reaches the set weight, the operator drives the crane 32 to lift the underwater suspended matter collection device 1 from the fuel storage pool 30, and on the operation floor. The respective connection states of the collection containers 12 and 15 and the collected material discharge pipes 22 and 23 are released, and the collection containers 12 and 15 filled with the concrete crushed pieces 36 are removed from the support member 2. Thereafter, empty collection containers 12 and 15 are attached to the support member 2 and the collected material discharge pipes 22 and 23 are connected to these collection containers.

  The crane 32 is driven to lower the underwater suspended matter collection device 1 with the empty collection containers 12 and 15 attached thereto into the cooling water 38 of the fuel storage pool 30. The suction and separation of the concrete fragments 36 in the storage pool 30 are performed.

  Since the weight of the underwater suspended matter collection device 1 is measured by the measuring device 37, the concrete fragment 36 collected in the collection containers 12 and 15 overflows with at least one of the collection containers 12 and 15 and overflows. It is possible to prevent the spent fuel assembly in the spent fuel storage container 35 from being dropped by being dropped on the spent fuel storage container 35 located below the suspended underwater suspended matter collection device 1. it can. Moreover, the concrete fragments 36 overflowed from the collection container are scattered in the cooling water 38 of the fuel storage pool 30, and it is necessary to collect the concrete fragments 36 again, and the concrete fragments 36 are collected. Work efficiency decreases. In this embodiment, since the measuring device 37 is attached to the crane 32 that suspends the underwater suspended matter collection device 1, such a problem does not occur.

  In the present embodiment, the surface temperature of the recovery container 12 is measured by the thermometer 24A, the surface temperature of the recovery container 15 is measured by the thermometer 24B, and the recovery container 12 is monitored by monitoring these measured temperatures. , 15, it can be determined whether the nuclear fuel material is contained in the solid content. In this determination, the dose rates of the collection containers 12 and 15 measured by the dosimeter 25 are also taken into consideration. When the nuclear fuel material is contained in the solid content (insoluble component) deposited on the spent fuel storage container 35 stored in the fuel storage pool 30, the nuclear fuel material is converted into concrete fragments. 36 is sucked together with the suction nozzle 3, separated by the pre-stage separator 4 and the public corporation separator 14, and collected in the collection containers 12 and 15. The surface temperature and the surface dose rate of the collection containers 12 and 15 increase when the recovered solid content contains nuclear fuel material. By increasing the surface temperature and the surface dose rate of the recovery containers 12 and 15 as described above, it is possible to confirm whether or not the nuclear fuel material is contained in the solid content recovered in these recovery containers. If there is a delay in the increase in the surface dose rate of the recovery container, the presence of nuclear fuel material in the recovery container can be determined based on the surface temperature.

  Moreover, since the present Example uses the thermometers 24A and 24B and the dosimeter 25, the following effects can be acquired. When the nuclear fuel material is contained in the solid contents collected in the recovery containers 12 and 15, respectively, if the amount of the nuclear fuel material recovered in the recovery containers 12 and 15 becomes too large, Recovered nuclear fuel material may become recritical. Just measuring the surface dose rate of the collection vessel makes it difficult to determine whether the dose rate has increased due to an increase in the amount of recovered nuclear fuel material or whether the dose rate has increased due to recriticality of the nuclear fuel material. . Based on the surface temperature of the recovery container measured with a thermometer, it can be easily determined whether or not the nuclear fuel material in the recovery container has become recritical. This is because when the nuclear fuel material in the recovery container becomes recritical, the surface temperature of the recovery container increases more rapidly than when the amount of nuclear fuel material in the recovery container increases.

  In addition, since the fuel storage pool 30 has a large amount of water, when there are few concrete fragments 36 present in the fuel storage pool 30 and the recovery operation of the concrete fragments 36 is completed in a short time, The filter device 16 may be deleted from the suspended matter collection device 1. This was discharged when the concentration of the concrete fragments of the cooling water 38 that passed through the rear separator 14 was low, and this cooling water 38 was discharged from the rear separator 14 into the cooling water 38 of the fuel storage pool 30. This is because the concrete fragment 36 contained in the cooling water 38 is diluted by the cooling water 38 of the fuel storage pool 30, so that there is no possibility of causing a decrease in visibility.

  The underwater suspended matter collection method according to embodiment 2, which is another preferred embodiment of the present invention, will be described with reference to FIG. In the underwater suspended matter recovery method of this embodiment, the underwater suspended matter containing the metal oxide (insoluble component) 54 derived from the nuclear fuel material in the reactor pressure vessel 50 of the boiling water nuclear power plant is Similarly, it is recovered using the underwater suspended matter recovery device 1.

  As shown in FIG. 8, the boiling water nuclear power plant has a reactor containment vessel 58 installed in a reactor building 57 and a reactor pressure vessel 50 installed in the reactor containment vessel 58. A cylindrical core shroud 51 that surrounds the core is installed in the reactor pressure vessel 50, and a plurality of jet pumps 52 are disposed between the reactor pressure vessel 50 and the core shroud 51. A core support plate 55 located at the lower end of the core is disposed in the core shroud 51 and installed in the core shroud 51. A plurality of control rod drive mechanism housings 53 penetrate through the bottom of the reactor pressure vessel 50 and are attached to the bottom.

  A reactor well 56 is formed directly above the reactor pressure vessel 50 and above the reactor containment vessel. The reactor well 56 is surrounded by an operation floor in the reactor building.

  With the operation of the boiling water nuclear power plant stopped, the upper covers of the reactor containment vessel and the reactor pressure vessel 50 are removed, and cooling water is filled into the reactor well 56 and the reactor pressure vessel 50. Suppose that Further, it is assumed that the metal oxide 54 derived from the nuclear fuel material is deposited in the reactor pressure vessel 50, for example, on the upper surface of the core support plate 55.

  A work carriage 31 is installed movably on the operation floor in the reactor building across the reactor well 5. The underwater suspended matter collection device 1 is suspended from a crane 32 provided with a weighing machine 31 as in the first embodiment, and is disposed in the cooling water in the reactor well 56. In addition, the dosimeter 25, the underwater camera 27, and the illumination 28 are suspended from the work carriage 31 and disposed in the cooling water 38. The suction nozzle 3 is attached to a lower end portion of a pole 33 held by an operator on the work carriage 31 and is disposed in the vicinity of the core support plate 55 in the reactor pressure vessel 50. When the pump 13 is driven, the metal oxide 54 that is floating on the core support plate 55 and the surrounding cooling water are sucked into the suction nozzle 3 and guided to the upstream separator 4. The metal oxide 54 having a size of 1 mm or more is removed by the front separator 4, the metal oxide 54 having a size of less than 1 mm is removed by the rear separator 14, and the metal oxide 54 that has passed through the rear separator 14 is filtered. It is removed by device 16. The cooling water discharged from the filter device 16 is discharged into the cooling water in the reactor pressure vessel through the drain pipe 21. The metal oxide 54 removed by the front separator 4 and the rear separator 14 is recovered in the recovery containers 12 and 15.

  In addition, when the reactor pressure vessel 30 is opened and the wall of the reactor building is damaged, the concrete fragment 36 may be mixed into the reactor pressure vessel 50. Concrete fragments 36 present in the reactor pressure vessel 50, for example, concrete fragments 36 present on the core support plate 55, can be sucked together with the metal oxide 54 by the suction nozzle 3. The sucked concrete crushed pieces 36 are also removed by the front-stage separator 4, the rear-stage separator 14, and the filter device 16, respectively, and are collected in the collection containers 12 and 15.

  In the present embodiment, each effect produced in the first embodiment can be obtained. When the recovery amount of the metal mixed oxide 54 containing the nuclear fuel component to the recovery containers 12 and 15 increases, the surface temperature of each of the recovery containers 12 and 15 may increase, and the soundness of the recovery containers 12 and 15 may decrease. There is. In addition, the recovery containers 12 and 15 that store the metal oxide 54 need to be stored in another container provided with a radioactive shield when the recovery containers 12 and 15 are lifted from the reactor well 56. For this reason, the collection | recovery which accommodated the metal oxide 54 in the range which the dose rate of the collection | recovery containers 12 and 15 provided in the underwater suspended solid collection | recovery apparatus 1 does not exceed the radiation shielding capability of another container which accommodates these collection containers. Containers 12 and 15 need to be replaced with empty collection containers 12 and 15. It is important to monitor the surface temperatures of the collection containers 12 and 15 with the thermometers 24A and 24B, and monitor the dose rates of the collection containers 12 and 15 with the dosimeter 25, respectively.

  An underwater suspended matter collection apparatus used in the underwater suspended matter collection method of Example 3, which is another preferred embodiment of the present invention, will be described with reference to FIG. The underwater suspended matter collection device 1A used in the underwater suspended matter collection method of the present embodiment is the same as the underwater suspended matter collection device 1 used in Examples 1 and 2, except that the rear stage separator 14, the collection container 15 and the transfer pipe 20 are deleted. It has a configuration. The transfer pipe 19 connected to the pump 13 is connected to the filter device 16. The other configuration of the underwater suspended matter collection device 1A is the same as that of the underwater suspended matter collection device 1.

  For example, when the solid content of the concrete fragment 36 or the like accumulated in the fuel storage pool 30 is small, the suspended matter in the fuel storage pool 30 is used in the same manner as in the first embodiment by using the underwater suspended matter collection device 1A. A concrete crushed piece 36 is sucked by the suction nozzle 3, and the sucked concrete crushed piece 36 is separated by the front separator 4 and collected in the collecting container 12. Concrete fragments 36 of less than 1 mm flowing out from the front separator 4 are removed by the filter device 16.

  In the present embodiment, each effect produced in the first embodiment can be obtained. The underwater suspended matter collection device 1A is more compact than the underwater suspended matter collection device 1 because the post-stage separator 14, the collection container 15 and the transfer pipe 20 are not provided.

  The underwater suspended matter collection method according to embodiment 4, which is another preferred embodiment of the present invention, will be described with reference to FIGS. In the underwater suspended matter recovery method of the present embodiment, the underwater suspended matter containing the metal oxide 54 derived from the nuclear fuel material in the pressure suppression chamber 61 of the boiling water nuclear power plant is the same as in the first embodiment. It is recovered using the recovery device 1.

  As shown in FIG. 8, the boiling water nuclear power plant has a reactor containment vessel 58 installed in a reactor building 57 and a reactor pressure vessel 50 installed in the reactor containment vessel 58. The reactor pressure vessel 50 is installed on a cylindrical pedestal 59 installed in the reactor containment vessel 58. A fuel storage pool 30 and a temporary equipment storage pool 63 are formed in the upper part of the reactor building 57. An annular torus chamber 60 is disposed at the bottom of the reactor building 57. An annular pressure suppression chamber 61 is installed in the torus chamber 60, and a plurality of vent pipes 62 connected to the reactor containment vessel 58 are inserted into the pressure suppression chamber 61. The tip of each vent pipe 62 is immersed in cooling water in the pressure suppression chamber 61.

  It is assumed that a metal oxide 54 that is a suspended matter derived from nuclear fuel material is deposited at the bottom in the pressure suppression chamber 61. There are two methods for recovering the metal oxide 54 in the pressure suppression chamber 61. In any method, the part of the support member 2 to which the front-stage separator 4, the pump 13, the rear-stage separator 14, and the filter device 16 of the submerged suspended matter collection device 1 are attached is within the torus chamber 60, the pressure suppression chamber. It arrange | positions at the corner part of the outer side of 61 (refer FIG. 7). The portion of the support member 2 is carried into the torus chamber 60 from the floor above the torus chamber 60. The torus chamber 60 and the pressure suppression chamber 61 are filled with water. For this reason, the part of the supporting member 2 of the underwater suspended solids recovery apparatus 1 is placed in water.

  A first method for recovering the metal oxide 54 from the pressure suppression chamber 61 is a method in which the operator operates the suction nozzle 3. A through hole 64 having a size through which the suction nozzle 3 can pass is formed in the ceiling of the torus chamber 60 and the ceiling portion of the pressure suppression chamber 61, respectively. These through holes 64 are formed right above the region where the metal oxide 54 is deposited in the pressure suppression chamber 61. An operator on the upper floor of the torus chamber 60 inserts the poles 23 having the suction nozzle 3 attached to the lower end portion thereof into the through holes 64, and the metal oxide 54 is deposited in the pressure suppression chamber 61. Lower to the area where you are. The suction nozzle 3 is connected by a hose 17 to a front separator 4 provided on the support member 2 disposed in the torus chamber 60. When the pump 13 is driven, the metal oxide 54 is sucked into the suction nozzle 3 together with the surrounding water and introduced into the pre-stage separator 4 as in the second embodiment. The metal oxide 54 having a particle size of 1 mm or more is separated by the front separator 4 and collected in the collection container 12. The metal oxide 54 having a particle size of less than 1 mm discharged from the front separator 4 is separated by the rear separator 14 and the filter device 16. The metal oxide 54 of less than 1 mm separated by the rear separator 14 is recovered in the recovery container 15. The water discharged from the filter device 16 is discharged into the water in the torus chamber 60.

  Also in the first method of this embodiment, the effects produced in Embodiment 2 can be obtained.

  When the metal oxide 54 is continuously deposited on the bottom of the pressure suppression chamber 61 in the ring-shaped axial center direction of the annular pressure suppression chamber 61, the through hole 64 is formed in the ceiling portion of the pressure suppression chamber 61. In the first method that needs to be performed, it is impossible to suck all the metal oxide 54 from the pressure suppression chamber 61.

  For this reason, in the second method for recovering the metal oxide 54 from the pressure suppression chamber 61, which solves the problem of the first method, the metal oxide 54 is sucked by the suction nozzle 3 attached to the traveling vehicle 45. To do. In the second method, the traveling vehicle 45 to which the suction nozzle 3 is attached is carried into the pressure suppression chamber 61 and the traveling vehicle 45 is moved within the pressure suppression chamber 61. The hose 17 connected to the suction nozzle 3 is separated from the front stage attached to the support member 2 disposed at the corner portion of the torus chamber 60 through a through hole (not shown) formed in the wall of the pressure suppression chamber 61. Connected to the device 4. In this second method, the underwater camera 27 is attached to the traveling vehicle 45, and the traveling direction of the traveling vehicle 45 is photographed by the underwater camera 27. The video imaged by the underwater camera 27 is displayed on, for example, the display device 26 placed outside the reactor building 57, and the volume state of the metal oxide 54 in the pressure suppression chamber 61 is determined based on this video image. Check. The traveling vehicle 45 is driven by remote control. By traveling the traveling vehicle 45 in the pressure suppression chamber 61, all the metal oxide 54 in the pressure suppression chamber 61 can be sucked and recovered in the recovery containers 12 and 15.

  When the collection containers 12 and 14 of the underwater suspended matter collection device 1 reach a predetermined dose rate due to the collection of the metal oxide 54, the underwater suspended matter collection device 1 is carried out to the floor above the torus chamber 60, and the metal oxide is collected. The collection containers 12 and 14 in which 54 is stored are taken out from the support member 2 and the underwater suspended matter collection apparatus 1 in which the empty collection containers 12 and 14 are installed is carried to the original position in the torus chamber 60. The recovery containers 12 and 14 in which the metal oxide 54 taken out from the underwater suspended solids recovery apparatus 1 is stored are stored in another container provided with a radioactive shield, as in the second embodiment. Transport to a predetermined place outside the reactor building 57.

  Each effect produced in Example 1 can also be obtained by the second method of the underwater suspended matter recovery method of this example. In the second method, since the metal oxide 54 is sucked by the suction nozzle 3 provided in the traveling vehicle 45, the metal present in the target region (for example, the pressure suppression chamber 61) is moved by moving the traveling vehicle 45. All the oxide 54 can be sucked and recovered.

  Since the underwater suspended matter collection device 1 is disposed in water, the radiation emitted from the metal oxide 54 collected in the collection containers 12 and 14 provided in the underwater suspended matter collection device 1 can be shielded by water. it can. This effect can also be obtained in the first to third embodiments.

  When the metal oxide 54 is sucked, water containing the metal oxide 54 flows through the hose 17. Therefore, in the first method described above, the hose 17 is laid at a position away from the operator and shielded against radiation. It is desirable to take measures.

  The underwater suspended matter collection method according to embodiment 5 which is another preferred embodiment of the present invention will be described with reference to FIGS. In the underwater suspended matter collection method of the present embodiment, the concrete fragment 36 that is a suspended matter existing in the equipment temporary storage pool 63 of the boiling water nuclear power plant is collected in the same manner as in the first embodiment.

  The work carriage 31 is installed so as to be movable on the operation floor in the reactor building 57 across the equipment temporary storage pool 63. An underwater suspended matter collection device 1 hung on a crane 32 having a measuring instrument 37 provided on the work carriage 31 is disposed in the water filled in the equipment temporary storage pool 63. The concrete fragments 36 accumulated on the bottom of the temporary storage pool 63 are sucked by the suction nozzle 3 attached to the lower end of the pole 33 scanned by the worker on the work carriage 31, and They are separated by the front separator 4, the rear separator 14, and the filter device 16, respectively, and recovered in the recovery containers 12 and 15.

  In the present embodiment, each effect produced in the first embodiment can be obtained.

  DESCRIPTION OF SYMBOLS 1,1A ... Underwater suspended matter collection | recovery apparatus 2 ... Support member, 3 ... Suction nozzle, 4 ... Pre-stage separator, 6 ... Cylindrical part, 7 ... Bottom part, 8 ... Partition plate, 9A ... Lowering area, 9B ... Ascending area 12, 15 ... collection container, 13 ... pump, 14 ... latter stage separator, 16 ... filter device, 17 ... hose, 18, 19, 20 ... transfer piping, 24A, 25B ... thermometer, 25 ... dosimeter, 26 ... Display device 30 ... Fuel storage pool 31 ... Work truck 35 ... Spent fuel storage container 36 ... Concrete fragment 37 ... Measuring instrument 45 ... Traveling car 50 ... Reactor pressure vessel 56 ... Reactor well 57 ... Reactor building, 60 ... Torus chamber, 61 ... Pressure suppression chamber, 63 ... Temporary equipment pool.

Claims (10)

  A support member, a separator attached to the support member and having a lower end connected to each other to form an ascending region and an ascending flow region, and a separator provided therein, and the descender connected to the separator A suction nozzle connected to a region, a suction pump attached to the support member, connected to the separation device and connected to the ascending region, and supported by the support member and connected to a lower end of the separation device. A recovery container communicated with the descending region, and the ratio L ′ / L of the length L ′ of the support plate to the height L of the separation device in the axial direction of the separation device is 0.4-0. An underwater suspended matter collection device characterized by existing in a range of .8.   The underwater suspended matter collection | recovery apparatus of Claim 1 which makes ratio L '/ L the range of 0.5-0.6.   The underwater suspended matter collection | recovery apparatus of Claim 1 or 2 which has a dose rate meter attached to the said supporting member, and measuring the dose rate of the said collection container.   The underwater suspended matter collection | recovery apparatus of Claim 3 which has a thermometer attached to the said supporting member and measuring the surface temperature of the said collection container.   The first separation device attached to the support member and disposed downstream of the suction pump, connected to the suction pump and supplied with an insoluble component discharged from the rising region of the first separation device The underwater suspended matter collection | recovery apparatus of Claim 1 provided with the 2nd separation apparatus of another type.   The said underwater suspended solid collection | recovery apparatus described in Claim 1 or 2 is arrange | positioned in water, the said insoluble component which exists in the said water is attracted | sucked with the water with the said suction nozzle, and contains the said insoluble component sucked Water flows into the descending region of the separation device, and the insoluble component is separated from the water by gravity settling in the descending region, and the separated insoluble component is recovered in the recovery container, and the separation device The water that has risen in the ascending region is discharged into the water outside the underwater suspended matter collection device.   The underwater suspended matter collection device is suspended in a crane having a weighing device and placed in the water, and when the weight of the underwater suspended matter collection device measured by the weighing device reaches a set weight, the separated The said collection | recovery container which accommodated the insoluble component is taken out from the said underwater suspended matter collection | recovery apparatus, an empty collection | recovery container is installed in the underwater suspended matter collection | recovery apparatus, and it connects to the lower end part of the said separation apparatus. Underwater suspended matter collection method.   The dose rate of the recovery container containing the separated insoluble component is measured with a dosimeter, and when the dose rate of the recovery container obtained by measurement reaches a set dose rate, the separated insoluble component The underwater suspended matter according to claim 6, wherein the collection container containing the wastewater is taken out from the underwater suspended matter collection device, and an empty collection container is installed in the underwater suspended matter collection device and connected to a lower end of the separation device. Collection method.   The method for recovering suspended matter in water according to claim 8, wherein a surface temperature of the recovery container containing the separated insoluble components is measured with a thermometer. The underwater suspended matter collection device includes a second separation device of a type different from the first separation device, which is attached to the support member and disposed downstream of the suction pump and connected to the suction pump. ,
The water containing the insoluble component that is smaller than the size of the insoluble component separated in the descending region of the first separator, discharged from the ascending region of the first separator, and passed through the suction pump The insoluble component is supplied to the second separation device and the insoluble component smaller than the size of the insoluble component separated in the descending region is separated in the second separation device. Collection method.

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