Radioactive material storage device and storage method

Abstract

To provide a storage device for radioactive material and a storage method capable of suppressing the increase in facility costs.SOLUTION: A storage device for radio active material includes: a storage container for storing radioactive material; a gas supply line having an air supply on / off valve capable of supplying a gas into the storage container; a gas exhaust line having an exhaust on / off valve capable of discharging a gas from the storage container; an exhaust fan placed in the gas exhaust line; a pressure detector that detects the pressure inside the storage container; and a control unit that is configured to control the air supply on / off valve and the exhaust on / off valve to open and close based on the detection result by the pressure detector and to control the operation of the exhaust fan.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a storage device and method for radioactive material. [Background technology]

[0002] Radioactive materials such as radioactive waste are stored in dedicated storage containers to ensure containment, and are then stored and managed in designated storage facilities. In this case, if the radioactive material contains moisture, there is a possibility that hydrogen will be generated by radiolysis. Therefore, conventionally, air has been supplied into the storage container or gas has been purged from the storage container, thereby achieving both containment of the radioactive material and prevention of hydrogen retention. For example, an example of a conventional storage device for radioactive material is described in Patent Document 1 below. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-128902 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional radioactive material storage devices supply air to storage containers placed inside a storage building while scavenging the gas inside. This requires highly reliable equipment such as air compressors, exhaust fans, piping, and filters installed in the storage building, which increases the cost of the equipment.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a radioactive material storage device and method that can suppress increases in equipment costs. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the radioactive material storage device of the present disclosure comprises a storage container for storing radioactive material, a gas supply line having an air intake valve and capable of supplying gas into the interior of the storage container, a gas discharge line having an exhaust valve and capable of discharging gas from the storage container, an exhaust fan provided on the gas discharge line, a pressure detector for detecting the pressure inside the storage container, and a control device for controlling the opening and closing of the air intake valve and the exhaust valve based on the detection result of the pressure detector and for controlling the operation of the exhaust fan.

[0007] In addition, the method for storing radioactive materials disclosed herein includes a step of maintaining the inside of a storage container that stores radioactive materials in a negative pressure state, a step of detecting the pressure inside the storage container, and a step of performing a scavenging process on the storage container when the pressure inside the storage container exceeds a predetermined upper pressure limit value. [Effects of the Invention]

[0008] According to the radioactive material storage device and storage method of the present disclosure, increases in equipment costs can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a radioactive material storage device according to this embodiment. [Figure 2] FIG. 2 is a flowchart for carrying out the scavenging process of the storage container. [Figure 3] FIG. 3 is a flowchart for carrying out the storage container monitoring process. [Figure 4] FIG. 4 is a flowchart for carrying out a response process when an abnormality occurs. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the embodiments. Furthermore, the components in the embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the so-called equivalent range.

[0011] <Radioactive material storage device> FIG. 1 is a schematic diagram showing the configuration of a radioactive material storage device according to this embodiment.

[0012] As shown in FIG. 1, the radioactive material storage device 10 includes a storage container 11, a gas supply line 12, a gas exhaust line 13, an exhaust fan 14, a pressure detector 15, a hydrogen concentration detector 16, and a control device 17.

[0013] One or more storage containers 11 are placed at predetermined positions. There is no limit to the number of storage containers 11 to be placed. The multiple storage containers 11 are placed at intervals. The storage container 11 stores radioactive material 100, such as radioactive waste, inside and keeps it sealed. Here, the radioactive material is, for example, radioactive waste generated in a reprocessing plant, radioactive waste generated in decommissioning work, spent nuclear fuel generated in a nuclear power plant, etc. The storage container 11 has a container body and a lid, although not shown. The storage container 11 is a shielding container. Depending on the contents, the neutron shielding function may be enhanced by using materials or resins containing boron and boron compounds that have neutron shielding function.

[0014] The storage container 11 may be configured to suppress an increase in hydrogen concentration by disposing a hydrogen adsorbent or a hydrogen recombination catalyst inside.

[0015] The storage container 11 is connected to a gas supply line 12 and a gas exhaust line 13. The gas supply line 12 can supply gas (air) from outside the storage container 11 to the inside of the storage container 11. The gas exhaust line 13 can exhaust gas from inside the storage container 11 to the outside.

[0016] The gas supply line 12 has an intake pipe 31, an intake connecting pipe 32, a branch pipe 33, a connecting hose 34, and a communicating pipe 35. The gas supply line 12 has a connecting pipe 35 provided with an intake on / off valve 36 and an intake air filter (e.g., a HEPA filter) 37. The intake pipe 31 is connected to the intake connecting pipe 32. A plurality of branch pipes 33 (three in this embodiment) are branched from the intake connecting pipe 32. The branch pipe 33 is connected to a communicating pipe 35 via a connecting hose 34. The communicating pipe 35 penetrates the storage container 11 and communicates with the interior of the storage container 11. The communicating pipe 35 is provided with an intake on / off valve 36 and an intake air filter 37. Here, the intake air filter 37 is provided between the intake on / off valve 36 and the storage container 11. The gas supply line 12 may be provided with the intake air filter 37 removed, and the intake air filter 37 may be provided in the intake pipe 31 instead.

[0017] The gas exhaust line 13 has an exhaust pipe 41, an exhaust connecting pipe 42, a branch pipe 43, a connecting hose 44, and a communicating pipe 45. The gas exhaust line 13 has an exhaust on / off valve 46 and an exhaust air filter (e.g., a HEPA filter) 47 provided on the communicating pipe 45. The exhaust pipe 41 is connected to the exhaust connecting pipe 42. A plurality of branch pipes 43 (three in this embodiment) are provided branching from the exhaust connecting pipe 42. The branch pipe 43 is connected to a communicating pipe 45 via a connecting hose 44. The communicating pipe 45 penetrates the storage container 11 and communicates with the interior of the storage container 11. The communicating pipe 45 is provided with an exhaust on / off valve 46 and an exhaust air filter 47. Here, the exhaust air filter 47 is provided between the exhaust on / off valve 46 and the storage container 11. The gas exhaust line 13 may be provided with no exhaust air filter 47 and the exhaust pipe 41 may be provided with the exhaust air filter 47 instead.

[0018] The exhaust fan 14 is provided in the gas discharge line 13. The exhaust fan 14 is provided in the exhaust pipe 41.

[0019] The pressure detector 15 is provided in the storage container 11 and connected to the control device 17. The pressure detector 15 detects the pressure inside the storage container 11. The pressure detector 15 outputs the detected pressure inside the storage container 11 to the control device 17. The hydrogen concentration detector 16 is provided in the storage container 11 and connected to the control device 17. The hydrogen concentration detector 16 detects the hydrogen concentration inside the storage container 11. The hydrogen concentration detector 16 outputs the detected hydrogen concentration inside the storage container 11 to the control device 17.

[0020] The control device 17 is connected to the exhaust fan 14, the intake air on-off valve 36, the exhaust air on-off valve 46, the pressure detector 15, and the hydrogen concentration detector 16. The control device 17 is connected to the exhaust fan 14, the intake air on-off valve 36, the exhaust air on-off valve 46, the pressure detector 15, and the hydrogen concentration detector 16 by a wired or wireless communication device. The control device 17 controls the opening and closing of the intake air on-off valve 36 and the exhaust air on-off valve 46 based on the detection results of the pressure detector 15 and the hydrogen concentration detector 16, and also controls the operation of the exhaust fan 14.

[0021] Specifically, the control device 17 controls the opening and closing of the air intake valve 36 and the exhaust valve 46, and also controls the operation of the exhaust fan 14, thereby maintaining a negative pressure state inside the storage container 11. Furthermore, when the pressure inside the storage container 11 exceeds a preset upper pressure limit, the control device 17 opens the air intake valve 36 and the exhaust valve 46 and operates the exhaust fan 14 to scavenge the inside of the storage container 11. When the hydrogen concentration inside the storage container 11 exceeds a preset upper hydrogen concentration limit, the control device 17 opens the air intake valve 36 and the exhaust valve 46 and operates the exhaust fan 14 to scavenge the inside of the storage container 11.

[0022] The storage container 11 stores radioactive material 100 with its interior maintained at a negative pressure. That is, by closing the air intake valve 36 and the exhaust valve 46, the gas supply line 12 and the gas exhaust line 13 are cut off from the outside, and the storage container 11 maintains a negative pressure state. The residual moisture and organic matter in the radioactive material 100 stored in the storage container 11 are decomposed by radiation, generating hydrogen and other substances. When hydrogen is generated, the pressure inside the storage container 11 increases, and the hydrogen concentration also increases. When the internal pressure of the storage container 11 increases, it becomes difficult to maintain a negative pressure state. Furthermore, when the hydrogen concentration inside the storage container 11 increases, there is a risk of a hydrogen explosion.

[0023] Therefore, the control device 17 monitors the pressure and hydrogen concentration inside the storage container 11, and when the pressure and hydrogen concentration exceed their upper limits, it purges the gas inside the storage container 11. Thereafter, the control device 17 maintains the inside of the storage container 11 in a negative pressure state again.

[0024] The control device 17 is a controller, and is realized by, for example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) executing various programs stored in a storage unit using a RAM as a working area.

[0025] Furthermore, an operation device 51 and a display device 52 are connected to the control device 17. The operation device 51 can be operated by an operator. When the operator operates the operation device 51, various command signals can be input to the control device 17. The operation device 51 is, for example, a keyboard or a touch-type display. The display device 52 displays the determination results and processing contents of the control device 17. The display device 52 is, for example, a monitor.

[0026] Furthermore, an earthquake detector 53 is connected to the control device 17. The earthquake detector 53 measures the seismic intensity of the storage container 11 and outputs the measured value to the control device 17. The control device 17 controls the opening and closing of the air intake valve 36 and the exhaust valve 46 based on the detection result of the earthquake detector 53. Specifically, the control device 17 closes the air intake valve 36 and the exhaust valve 46 when the seismic intensity detected by the earthquake detector 53 exceeds a preset upper seismic intensity limit.

[0027] <Methods for storing radioactive materials> The method for storing radioactive material in this embodiment includes a step of maintaining the inside of a storage container 11 containing radioactive material 100 in a negative pressure state, a step of detecting the pressure inside the storage container 11, and a step of performing a scavenging process on the storage container 11 when the pressure inside the storage container 11 exceeds a preset upper pressure limit value.

[0028] <Storage vessel scavenging process> First, a description will be given of the scavenging process of the storage container 11, which creates a negative pressure state inside the storage container 11. Fig. 2 is a flowchart for carrying out the scavenging process of the storage container.

[0029] As shown in FIGS. 1 and 2, radioactive material 100 is stored inside storage container 11. In step S11, control device 17 opens air intake valve 36 and exhaust valve 46. In step S12, control device 17 operates exhaust fan 14. When exhaust fan 14 operates, a suction force acts on the inside of storage container 11 from gas exhaust line 13, and gas inside storage container 11 is exhausted to the outside through gas exhaust line 13. At the same time, outside air is supplied to the inside of storage container 11 through gas supply line 12. Therefore, storage container 11 is purged by exhausting internal gas to the outside and filling with outside air.

[0030] In step S13, the control device 17 determines whether a predetermined time has elapsed since the air intake valve 36 and the air exhaust valve 46 were opened to operate the exhaust fan 14. Here, the predetermined time is the time required for all the gas inside the storage container 11 to be exhausted to the outside and replaced with external air, and is set according to the volume of the storage container 11 and the capacity of the exhaust fan 14, and is determined in advance by experiment, simulation, or the like.

[0031] If the control device 17 determines in step S13 that a predetermined time has not elapsed since the air intake valve 36 and the exhaust valve 46 were opened and the exhaust fan 14 was operated (No), the process continues. On the other hand, if the control device 17 determines that a predetermined time has elapsed since the air intake valve 36 and the exhaust valve 46 were opened and the exhaust fan 14 was operated (Yes), the control device 17 closes the air intake valve 36 in step S14. This closes the gas supply line 12, thereby stopping the supply of air to the interior of the storage container 11 through the gas supply line 12. Meanwhile, as the operation of the exhaust fan 14 continues, the gas inside the storage container 11 is exhausted to the outside through the gas exhaust line 13. Therefore, the interior of the storage container 11 becomes negative pressure as the gas inside is exhausted to the outside.

[0032] In step S15, the control device 17 determines whether the pressure inside the storage container 11 has reached a predetermined specified negative pressure. Here, the specified negative pressure is a pressure for maintaining the inside of the storage container 11 in a negative pressure state, which is lower than atmospheric pressure and is set in advance.

[0033] If the control device 17 determines in step S15 that the pressure inside the storage container 11 has not reached the specified negative pressure (No), the process continues. On the other hand, if the control device 17 determines that the pressure inside the storage container 11 has reached the specified negative pressure (Yes), the control device 17 closes the exhaust on-off valve 46 in step S16. Then, the exhaust fan 14 is stopped in step S17. Then, in step S18, the inside of the storage container 11 is maintained at a specified negative pressure state (specified negative pressure).

[0034] <Storage container monitoring process> Next, a description will be given of a monitoring process for the storage container 11, which monitors the radioactive material 100 stored in the storage container 11. Fig. 3 is a flowchart for carrying out the monitoring process inside the storage container.

[0035] As shown in Figures 1 and 3, radioactive material 100 is stored inside storage container 11, and the interior is maintained at a predetermined negative pressure state (specified negative pressure) by the above-mentioned scavenging process. Over time, residual moisture and organic matter in radioactive material 100 stored in storage container 11 are decomposed by radiation, generating hydrogen and other substances. The internal pressure of storage container 11 increases due to the generation of hydrogen from radioactive material 100, a temperature rise, and the like. Control device 17 monitors the generation of hydrogen from radioactive material 100, the pressure rise, and the like.

[0036] In step S21, the control device 17 determines whether the pressure inside the storage container 11 has exceeded a preset upper pressure limit. The control device 17 compares the pressure inside the storage container 11 detected by the pressure detector 15 with the upper pressure limit. Here, the upper pressure limit is a pressure at which the inside of the storage container 11 cannot be maintained in a confined state, and may be, for example, a pressure higher than atmospheric pressure. If the control device 17 determines that the pressure inside the storage container 11 has not exceeded the upper pressure limit (No), the control device 17 proceeds to step S22. On the other hand, if the control device 17 determines that the pressure inside the storage container 11 has exceeded the upper pressure limit (Yes), the control device 17 proceeds to step S23.

[0037] That is, when the internal pressure has not increased due to hydrogen generation or a temperature rise, in step S22, the control device 17 determines whether the hydrogen concentration inside the storage container 11 has exceeded a preset hydrogen concentration upper limit. The control device 17 compares the hydrogen concentration inside the storage container 11 detected by the hydrogen concentration detector 16 with the hydrogen concentration upper limit. Here, the hydrogen concentration upper limit is the hydrogen concentration at which the concentration of hydrogen generated inside the storage container 11 becomes so high that it poses a risk of explosion, and is determined in advance by experiment, etc.

[0038] If the control device 17 determines that the hydrogen concentration inside the storage container 11 does not exceed the hydrogen concentration upper limit (No), it exits this routine. On the other hand, if the control device 17 determines that the hydrogen concentration inside the storage container 11 exceeds the hydrogen concentration upper limit (Yes), it proceeds to step S23.

[0039] If the pressure inside the storage container 11 exceeds the upper pressure limit or the hydrogen concentration inside the storage container 11 exceeds the upper hydrogen concentration limit, the above-described scavenging process for the storage container 11 is executed in step S23 and subsequent steps. That is, in step S23, the control device 17 opens the intake valve 36 and the exhaust valve 46. In step S24, the control device 17 operates the exhaust fan 14. In step S25, the control device 17 determines whether a predetermined time has elapsed since the intake valve 36 and the exhaust valve 46 were opened and the exhaust fan 14 was operated. If the control device 17 determines that the predetermined time has not elapsed since the intake valve 36 and the exhaust valve 46 were opened and the exhaust fan 14 was operated (No), the control device 17 continues the process. On the other hand, if the control device 17 determines (Yes) that a predetermined time has elapsed since the air intake valve 36 and the exhaust valve 46 were opened and the exhaust fan 14 was operated, then in step S26, the control device 17 closes the air intake valve 36.

[0040] In step S27, the control device 17 determines whether the pressure inside the storage container 11 has reached the specified negative pressure. If the control device 17 determines that the pressure inside the storage container 11 has not reached the specified negative pressure (No), the control device 17 continues the processing. On the other hand, if the control device 17 determines that the pressure inside the storage container 11 has reached the specified negative pressure (Yes), the control device 17 closes the exhaust on-off valve 46 in step S28. Then, in step S29, the exhaust fan 14 is stopped. Then, in step S30, the interior of the storage container 11 is maintained at a specified negative pressure state (specified negative pressure).

[0041] <Response process when an abnormality occurs> Finally, a description will be given of the process for dealing with an abnormality when an abnormality occurs, by dealing with the storage container 11. Fig. 4 is a flowchart for carrying out the process for dealing with an abnormality when an abnormality occurs.

[0042] 1 and 4, radioactive material 100 is stored inside storage container 11, and the inside is maintained at a predetermined negative pressure (prescribed negative pressure). If an abnormality occurs in storage container 11 or the like in this state, it may become difficult for storage container 11 to maintain the safety of radioactive material 100, and therefore control device 17 monitors storage container 11 and the like for abnormalities.

[0043] In step S41, the control device 17 determines whether or not an abnormality has been detected. Specifically, the control device 17 determines whether or not the seismic intensity detected by the earthquake detector 53 exceeds a preset upper seismic intensity limit. The control device 17 compares the seismic intensity detected by the earthquake detector 53 with the upper seismic intensity limit. Here, the upper seismic intensity limit is a seismic intensity at which the safety of the storage container 11 and the like cannot be ensured, and is set in advance.

[0044] If the control device 17 determines that the seismic intensity detected by the earthquake detector 53 does not exceed the seismic intensity upper limit (No), it exits this routine. On the other hand, if the control device 17 determines that the seismic intensity detected by the earthquake detector 53 exceeds the seismic intensity upper limit (Yes), in step S42, the control device 17 closes the air intake valve 36 and the exhaust valve 46. In step S43, the control device 17 determines whether or not there is an abnormality in the various devices. Here, the various devices refer to the gas supply line 12, the gas exhaust line 13, the exhaust fan 14, the pressure detector 15, the hydrogen concentration detector 16, etc. The control device 17 determines whether or not there is damage to the various devices based on input from damage detectors provided in the various devices. The control device 17 may also determine whether or not there is damage to the various devices based on information input by an operator about the state of damage to the devices.

[0045] If the control device 17 determines in step S43 that there is no damage to the various devices (No), then in step S44 it executes a scavenging process for the storage container 11 using regular equipment. The scavenging process for the storage container 11 using regular equipment is the scavenging process that is executed using existing equipment and that was explained using FIG. 2. On the other hand, if the control device 17 determines that there is damage to the various devices (Yes), then in step S45 it executes a scavenging process for the storage container 11 using emergency equipment. The scavenging process for the storage container 11 using emergency equipment is a scavenging process that uses emergency equipment that is prepared separately from the existing equipment. That is, the worker prepares portable air intake and exhaust equipment as emergency equipment, connects the portable air intake and exhaust equipment to the storage container 11, and executes a scavenging process.

[0046] For example, if an earthquake occurs during the scavenging process of the storage container 11, the open air intake valve 36 and the exhaust valve 46 are immediately closed. Also, if an earthquake occurs while the storage container 11 is being maintained at negative pressure, the closed air intake valve 36 and the exhaust valve 46 remain closed. After checking the damage status of the various equipment, scavenging is carried out using regular equipment or emergency equipment, and a negative pressure state is maintained in the storage container 11 containing the radioactive material 100.

[0047] [Effects of this embodiment] The radioactive material storage device of the first aspect comprises a storage container 11 for storing radioactive material 100, a gas supply line 12 having an air intake valve 36 and capable of supplying gas into the interior of the storage container 11, a gas discharge line 13 having an exhaust valve 46 and capable of discharging gas from the storage container 11, an exhaust fan 14 provided on the gas discharge line 13, a pressure detector 15 for detecting the pressure inside the storage container 11, and a control device 17 for controlling the opening and closing of the air intake valve 36 and the exhaust valve 46 based on the detection result of the pressure detector 15 and for controlling the operation of the exhaust fan 14.

[0048] In the radioactive material storage device according to the first aspect, the control device 17 controls the opening and closing of the air intake valve 36 and the exhaust valve 46 based on the pressure inside the storage container 11, and also controls the operation of the exhaust fan 14. That is, the storage container 11 can create a negative pressure inside by operating the exhaust fan 14. While the storage container 11 is maintained at a negative pressure, the control device 17 controls the opening and closing of the air intake valve 36 and the exhaust valve 46 based on the pressure inside the storage container 11, and also controls the operation of the exhaust fan 14, thereby scavenging the inside of the storage container 11 and maintaining the negative pressure after scavenging. As a result, the control device 17 does not need to operate the exhaust fan 14 all the time, and there is no need to ensure high reliability for various pieces of equipment such as the gas supply line 12, the gas exhaust line 13, and the exhaust fan 14, which can suppress increases in equipment costs.

[0049] The radioactive material storage device according to the second aspect is the radioactive material storage device according to the first aspect, and further, the control device 17 maintains the inside of the storage container 11 in a negative pressure state by controlling the operation of the exhaust fan 14. This makes it possible to easily ensure a negative pressure state inside the storage container 11.

[0050] The radioactive material storage device according to the third aspect is the radioactive material storage device according to the first or second aspect, and further, when the pressure inside the storage container 11 exceeds a preset upper pressure limit, the control device 17 opens the exhaust on-off valve 46 and activates the exhaust fan 14. As a result, when the negative pressure state cannot be maintained due to an increase in the pressure inside the storage container 11, the storage container 11 can be maintained in a negative pressure state again after performing a process of purging the inside of the storage container 11.

[0051] The radioactive material storage device according to the fourth aspect is the radioactive material storage device according to any one of the first to third aspects, further comprising a hydrogen concentration detector 16 that detects the hydrogen concentration inside the storage container 11, and when the hydrogen concentration inside the storage container 11 exceeds a preset upper limit of hydrogen concentration, the control device 17 opens the air intake valve 36 and the exhaust valve 46 and operates the exhaust fan 14. As a result, when safety cannot be maintained due to an increase in the hydrogen concentration inside the storage container 11, the storage container 11 can be maintained in a negative pressure state again after performing a purge process inside the storage container 11.

[0052] The radioactive material storage device according to the fifth aspect is the radioactive material storage device according to any one of the first to fourth aspects, further comprising an air intake filter 37 provided in the gas supply line 12 between the air intake on-off valve 36 and the storage container 11, and an exhaust air filter 47 provided in the gas discharge line 13 between the exhaust on-off valve 46 and the storage container 11. This prevents harmful substances such as radioactive material 100 from adhering to the gas supply line 12, the gas discharge line 13, and the exhaust fan 14, eliminates the need to require high reliability for the gas supply line 12 and the gas discharge line 13, and ensures safety in maintenance and replacement work.

[0053] The radioactive material storage device according to the sixth aspect is the radioactive material storage device according to any one of the first to fifth aspects, further comprising an earthquake detector 53, and the control device 17 controls the opening and closing of the air intake valve 36 and the exhaust valve 46 based on the detection result of the earthquake detector 53. As a result, by closing the air intake valve 36 and the exhaust valve 46 when an earthquake occurs, it is possible to ensure the containment of the storage container 11 and improve safety even if an earthquake occurs and various pieces of equipment are damaged.

[0054] The radioactive material storage device according to the seventh aspect is the radioactive material storage device according to any one of the first to sixth aspects, and further, the storage container 11 is a shielding container made of a radiation shielding material. This allows the radioactive material 100 to be safely stored inside the storage container 11.

[0055] The method for storing radioactive material according to the eighth aspect includes the steps of maintaining the inside of storage container 11 storing radioactive material 100 in a negative pressure state, detecting the pressure inside storage container 11, and purging storage container 11 when the pressure inside storage container 11 exceeds a preset upper pressure limit. This eliminates the need to operate exhaust fan 14 all the time and the need to ensure high reliability for various pieces of equipment such as gas supply line 12, gas exhaust line 13, and exhaust fan 14, thereby suppressing increases in equipment costs.

[0056] In the above-described embodiment, a temperature detector for detecting the temperature inside the storage container 11 and an oxygen concentration detector for detecting the oxygen concentration inside the storage container 11 may be provided. In this case, the control device 17 is preferably configured to control the opening and closing of the air supply valve 36 and the exhaust valve 46 and to control the operation of the exhaust fan 14 in accordance with the temperature detector and the oxygen concentration detector. [Explanation of symbols]

[0057] 10 Radioactive material storage device 11 Storage container 12 Gas supply line 13 Gas exhaust line 14 Exhaust fan 15 Pressure detector 16 Hydrogen concentration detector 17 Control device 36 Air intake valve 37 Intake air filter 46 Exhaust valve 47 Exhaust Air Filter 53 Earthquake Detector 100 Radioactive materials

Claims

1. a storage container for storing radioactive materials; a gas supply line having an air supply opening / closing valve for supplying gas into the storage container; a gas exhaust line having an exhaust on-off valve for exhausting gas from the storage container; an exhaust fan provided in the gas discharge line; a pressure detector for detecting the pressure inside the storage container; An earthquake detector; a control device that controls the opening and closing of the intake valve and the exhaust valve based on the detection result of the pressure detector, and also controls the operation of the exhaust fan, and that controls the opening and closing of the intake valve and the exhaust valve based on the detection result of the earthquake detector; A radioactive material storage device comprising:

2. The control device controls the operation of the exhaust fan to maintain a negative pressure inside the storage container. The radioactive material storage device according to claim 1.

3. When the pressure inside the storage container exceeds a preset upper pressure limit, the control device opens the exhaust opening / closing valve and operates the exhaust fan.

3. The radioactive material storage device according to claim 1 or 2.

4. a hydrogen concentration detector for detecting the hydrogen concentration inside the storage container; When the hydrogen concentration inside the storage container exceeds a predetermined hydrogen concentration upper limit value, the control device opens the air intake valve and the exhaust valve and operates the exhaust fan.

3. The radioactive material storage device according to claim 1 or 2.

5. the gas supply line is provided with an air intake filter between the air intake on-off valve and the storage container, and the gas exhaust line is provided with an exhaust filter between the exhaust on-off valve and the storage container; The radioactive material storage device according to claim 1.

6. The storage container is a shielding container made of a radiation shielding material. The radioactive material storage device according to claim 1.

7. maintaining the inside of a storage container that stores radioactive materials in a negative pressure state; detecting a pressure inside the container; a step of purging the storage container when the pressure inside the storage container exceeds a preset upper pressure limit; a step of closing the gas supply line and the gas exhaust line when the seismic intensity of the earthquake exceeds a preset upper seismic intensity limit; A method for storing radioactive materials.

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