JP5124548B2 - Powder sampling device - Google Patents

Description

  The present invention relates to an apparatus for sampling radioactive radioactive powder in the course of processing in the reprocessing of spent nuclear fuel generated from a nuclear power plant.

  Conventionally, a technique called a PUREX method is known among those skilled in the art as a technique for reprocessing spent nuclear fuel generated from a nuclear power plant that is a nuclear power plant.

  In the PUREX method using the solvent extraction method, the products uranium U (hereinafter simply referred to as U) and the metal oxide fuel MOX (or plutonium Pu) are recovered with a high degree of purification. The main process requires a large separation system called solvent extraction, and a large amount of liquid waste is generated, so reprocessing costs tend to be high, and facility downsizing and disposal to improve economy It is necessary to reduce the quantity.

  On the other hand, as a technique for reprocessing spent nuclear fuel, a fluoride volatilization method which is one of dry reprocessing methods is known among those skilled in the art. This method has an advantage that U with high purity can be recovered with a small equipment, but it is known that it is difficult to separate and purify plutonium Pu (hereinafter simply referred to as Pu).

  Therefore, by providing a U separation / purification process upstream of the PUREX process, the equipment for carrying out the PUREX process can be downsized, and the complement of the fluoride volatilization process, which is difficult to purify Pu, is complemented. The FLUOREX method, which is a hybrid reprocessing method, has been developed (see Patent Document 1 and Non-Patent Document 1).

In this FLUOREX method, 90% or more of U which occupies most of the spent nuclear fuel in a light water reactor, which is one of the types of nuclear reactors, is converted to gaseous uranium hexafluoride UF ₆ by the fluorination reaction (hereinafter simply referred to as UF Only written as _6. ) Convert, volatilize and separate. That is, in the decoating process, the spent fuel of the light water reactor is powdered. The powdered oxide and high-concentration fluorine F ₂ gas (hereinafter simply referred to as F ₂ gas) are introduced into a tower-like flame furnace, and U in the nuclear fuel is UF at a temperature of about 1200 ° C. Switch to ₆ . This UF ₆ can be purified by a still or adsorbent.

Since U as a reprocessing product is a chemical form of UF ₆ used for U enrichment, it can be used in U enrichment and conversion facilities without going through the conversion facility, and can be reused as fuel. The remaining 10% or less of U and Pu from which most of U has been removed and the non-volatile radioactive fission product FP (hereinafter simply referred to as FP) fluoride are converted into soluble oxides. Dissolve in nitric acid and purify using the PUREX method.

JP 2002-257980 A

Thermal Power Generation Vol.54 No.12 (Dec.2003) Pages 46-54

  In the fluorination process incorporated in the process of reprocessing spent nuclear fuel in this manner, since fluorine is used, hydrogen fluoride HF (hereinafter, simply referred to as HF) generated by mixing air is used. It is necessary to reduce the effect of corrosion products on the fluorination behavior of spent nuclear fuel and the material corrosion. In addition, since hydrogen fluoride is extremely permeable to living organisms, special care is required to prevent inhalation of HF generated in the reprocessing process or contact with HF even if diluted.

  Therefore, in the fluoridation process which is a fluorine atmosphere, radioactive substances and fluorine are also sampled when sampling fluoride from a powder container in which non-volatile U, Pu and FP radioactive powders are retained for the purpose of measurement control and process control. There is a need for a sampling device that allows isolation between the atmosphere and the outside of the reprocessing system.

  Accordingly, an object of the present invention is to safely sample a radioactive radioactive powder of fluoride produced in the process of reprocessing spent nuclear fuel.

  Basic means for achieving the object of the present invention is provided for a powder container in which radioactive powder of non-volatile fluoride generated during a reprocessing step of spent nuclear fuel is retained, and the powder A sampling device for collecting the radioactive powder in the container, a separating device for isolating and communicating between the inside of the casing surrounding the outer periphery of the sampling device and the inside of the powder container, and inertness to the casing A powder sampling apparatus comprising a gas (for example, argon gas; hereinafter simply referred to as Ar gas) injection means and a pressure adjusting means for making the pressure in the casing higher than the pressure in the powder container. is there.

  By providing such basic means, when sampling from the powder container in which the radioactive powder of the non-volatile fluoride is retained in the fluorination step which is a fluorine atmosphere, the casing of the sampling device is used by the Ar gas injection means. Ar gas is injected into the inside of the casing of the sampling device to replace it with Ar gas, and the isolation device enables sampling operation as “open” when sampling the powder in the powder container, and “closed” after completion of sampling. The inside of the powder container that is an atmosphere and the inside of the casing of the sampling apparatus that is not a fluorine atmosphere can be isolated. At the time of powder sampling, the pressure in the casing of the sampling apparatus is made higher than the pressure in the powder container by the pressure adjusting means. So that even if the isolation device is “open” during sampling, the sampling device Prevents the atmosphere in the powder container flows into pacing inwardly to prevent leakage of gas from the powder container is a fluorine atmosphere.

When sampling the radioactive powder of non-volatile fluoride from the fluorination process in a fluorine atmosphere, it is possible to prevent leakage of fluorine gas and radioactive materials outside the fluorine atmosphere system, and to the fluorine atmosphere system outside the system Thus, moisture can be mixed in addition to Ar gas and HF can be generated by the reaction of the F ₂ gas and moisture, and the occurrence of material corrosion due to HF can be suppressed or prevented.

It is a system | strain flowchart of the spent nuclear fuel reprocessing process provided with the powder sampling apparatus which concerns on the implementation line 1 of this invention. It is a whole schematic diagram of the powder sampling device of FIG. It is a schematic diagram of the sampler insertion apparatus and sample container handling apparatus in the powder sampling apparatus of FIG. It is a schematic diagram of the sampler sampling port handling apparatus of the sampler of FIGS. FIG. 2 is a cross-sectional view showing the open / close state of the sampler sampling port of the sampler of FIG. 1, FIG. 2 and FIG. 3, wherein (a) is a closed state and (b) is an open state.

  Hereinafter, embodiments of the present invention will be described in detail.

As shown in FIG. 1, the system flow of the fluorination process in the FLUOREX method is that the spent nuclear fuel is pulverized in advance to be used nuclear fuel powder, and the spent nuclear fuel powder is passed through the powder supply line 1 to the flame furnace. 4 is supplied. Ar gas is supplied from the Ar gas supply line 2 as a carrier gas for the spent nuclear fuel powder. F ₂ gas for fluorinating the spent nuclear fuel powder is supplied from the F ₂ gas supply line 3 to the flame furnace 4.

In this way, spent nuclear fuel powder and F ₂ gas are introduced into the flame furnace 4, and most of the U in the powder is converted into gaseous UF ₆ by the fluorination reaction to be volatilized and separated. Further, a part of the FP in the powder is also converted into a gaseous fluoride by a fluorination reaction, volatilized and separated. Volatilized UF ₆ such gas is supplied to the equipment which controls the UF ₆ purification step, where it is purified and transferred to the equipment which controls the UF ₆ recovery step of the next step.

Although most of U is volatilized by the fluorination reaction in the flame furnace 4, the radioactive powder of non-volatile U, Pu and FP fluoride is recovered as a residue in a residue recovery container 5 which is a powder container. The
The collected residue is transported by the residue transport device 8 to the facility that manages the oxide conversion treatment process.

  Here, it is necessary to sample the residue collected and retained in the residue collection container 5 for measurement management and process management for confirming the operation state of the flame furnace 4. The sampling involves the following problems. That is, in the fluorination process, since fluorine is used, it is necessary to reduce the influence on the fluorination behavior of the spent nuclear fuel and the material corrosion by the corrosion product HF generated by mixing air. In addition, since HF is extremely permeable to living organisms, special attention must be paid to fluorine leakage so that HF is not inhaled or contacted even if diluted.

  Therefore, when sampling the residue from the residue collection container 5, there is no inflow of air into the equipment that controls the fluorination process, and powder sampling with a sequestering function that prevents leakage of radioactive substances and fluorine. It is necessary to use a device.

  Such a sampling apparatus is as follows in this embodiment. That is, as in the configuration of the powder sampling apparatus of FIGS. 2 and 3, the sampling apparatus 20 has a casing 10 that encloses the outer shell of the apparatus, and a cylinder that connects the casing 10 and the residue collection container 5 in communication. And a guide tube 22 having a shape. In this manner, the sampling device 20 is shielded from the atmosphere around the sampling device 20 unless the opening is intentionally opened.

  The guide tube 22 has a function of protecting and protecting the passage of the sampler 23 inserted and removed between the sampling device 20 and the residue collection container 5. An intermediate portion of the guide tube 22 includes a residue collection container 5 in the radioactive powder and fluorine atmosphere system and an isolation device 21 for isolating the sampling device 20 outside the system. The isolation device 21 can employ a ball valve as an example, and it is preferable that the ball valve can be remotely driven electrically.

  When the isolation device 21 is opened, the isolation is released, and the sampler 23 can pass up and down in the guide tube 22 and the isolation device 21 to reach the residue collection container 5. Further, when the isolation device 21 is closed and partitioned, the sampling device 20 and the residue collection container 5 are in an isolated state where the atmosphere cannot be communicated.

As shown in FIGS. 2 and 3, the sampling device 20 is equipped with Ar gas injection means.
That is, a gas supply pipe is connected as an Ar gas introduction line 25 from the Ar gas high pressure gas source so as to communicate with the inside of the casing 10. A pressure adjusting valve 24 is provided as a pressure adjusting means in the middle of the gas supply pipe of the Ar gas introduction line 25. The pressure adjustment valve 24 is configured such that the pressure in the casing 10 is higher than the pressure in the residue collection container 5 known in advance based on the detection result by the pressure gauge P that detects the pressure in the casing 10. The feedback control is applied.

  An exhaust device 26 is connected to the casing 10 so that the atmosphere in the casing 10 can be exhausted outside the casing 10. The atmosphere in the casing 10 is changed to an Ar gas atmosphere from the Ar gas introduction line 25. Replacement can be performed smoothly.

  Thus, in order to replace the atmosphere in the sampling device 20, the pressure gauge P for adjusting the pressure in the sampling device 20, that is, the pressure in the casing 10, the pressure adjustment valve 24 and the Ar gas introduction line 25 are provided. The sampling device has an exhaust device 26 that exhausts the inside of the sampling device 20.

Because of such a configuration, when sampling is not performed, that is, when the sampler 23 is accommodated in the sampling device 20 (see FIG. 3), the flow path in the guide tube 22 is partitioned by the separating device 21. it is possible to prevent the residual渣回container 5 in radioactive material and fluorine atmosphere based F ₂ gas to the outside of the system, leakage of radioactive material by, it is possible to prevent moisture contamination into the system, wet It is possible to prevent HF formation and corrosion due to HF due to the reaction between the component and F ₂ gas.

When sampling is performed, that is, when the sampler 23 is inserted into the residue collection container 5 without partitioning the flow path in the guide tube 22 by the isolator 21, the pressure gauge P, the pressure adjustment valve 24, and the Ar gas By making the pressure in the sampling device 20 higher than the pressure in the residue collection container 5 by the introduction line 25, the gas flow becomes the residue collection container 5 side, so that F ₂ gas from the residue collection container 5 to the outside of the system, Leakage of radioactive material can be prevented. Further, Ar gas flows into the residue collection container 5, but it is not air containing moisture, so that moisture can be prevented from being mixed into the system, and HF can be generated and reacted with F ₂ gas. Corrosion due to HF can be prevented. The sampling device 20 performs pressure management using the pressure gauge P, the pressure adjusting valve 24 and the Ar gas introduction line 25 so as to be higher than the pressure in the residue collection container 5.

  Further, when gas is flowing into the sampling device 20 side from the residue collection container 5 which is a fluorine atmosphere during sampling, the inside of the sampling device 20, that is, the inside of the casing 10 is evacuated by the exhaust device 26, and Ar gas Ar gas is supplied from the introduction line 25, and the inside of the casing 10 of the sampling device 20 can be replaced with Ar gas instead of the gas from the residue collection container 5.

  The equipment configuration housed in the casing 10 of the sampling device 20 is as follows. That is, as shown in FIG. 3, a sampler insertion device 30, a sample container handling device 31, a sampler 23, and a sampler sampling port handling device 40 are housed in the casing 10.

  The sampler insertion device 30 inserts and removes the sampler 23 in the residue collection container 5, and at that time, the sampler insertion device driving device 30a for moving in the vertical direction, the two rails 30b, and the vertical movement It has a guide 30c to assist. As the drive device, a device that rotates a pinion meshed with a rack provided on the rail 30b by an electric motor or a screw feed device that rotates a nut screwed to the rail 30b as a screw can be used. The apparatus is configured to be remotely controlled from the outside of the casing 10.

  The sampler insertion device 30 enables smooth insertion and extraction of the sampler 23 into the residue collection container 5 by a drive device 30a that can move the rail 30b on one side and a guide 30c that assists movement in the vertical direction on the opposite side. .

  Regarding the movement of the sampler 23 in the vertical direction, when a cylinder or the like is used when pulling out the sampler 23, an upper pull-out space is required above the sampling device 20. Therefore, the sampling device 20 does not require the pull-out space. In order to reduce the size, a moving method having a driving device 30a capable of moving the two rails 30b is adopted.

  The sample container handling device 31 has a function of transferring the sample container 32 from the casing 10 of the sampling device 20 to the sample container transport device 11. The function is achieved, for example, by discharging the arm 12 on which the sample container 32 is mounted by horizontally rotating it, moving it to the sample container transporting device 11 disposed outside the casing 10 and changing it. At the time of this discharge, a part of the casing 10 facing the sample container receiving portion of the sample container transport device 11 is opened by the electric shutter 13 so that the sample container 32 and the arm 12 can pass through, or the casing 10 is sealed. Or to be closed. A drive device such as an electric motor that horizontally rotates the arm 12 of the sample container handling device 31 is configured to be remotely controlled from the outside of the casing 10. Since the electric shutter 13 provides a function of opening and closing a part of the casing 10, any type of opening and closing means may be used as long as it has such a function.

  As shown in FIG. 5, the sampler 23 is provided with a sampler tip collection port 23 a at the lower end of the cylindrical main pipe 14. The sampler tip collection port 23a is a sampler tip collection port support rod 23b inserted into the cylindrical main pipe 14 so as to be movable up and down, and the top 15 fixed to the lower end thereof is pulled upward. It can be opened as shown in FIG. 5B by being closed as shown in FIG.

  The top 15 has a partly constricted structure, and by opening and closing the sampler tip collection port 23a as shown in FIGS. 5A and 5B in the radioactive powder in the residue collection container 5, The radioactive powder can be sandwiched between the constricted portion and the inner wall surface of the main tube 14 and collected in the main tube.

  A sampler sampling port handling device 40 is a device that drives the sampler tip portion sampling port support bar 23b up and down. The sampler sampling port handling device 40 is installed in a driving device 30a that moves up and down along the rail 30b, and enables the sampler tip sampling port support bar 23b to be driven up and down by a driving device such as a piston cylinder device or a screw feeding device. By this driving, the sampler tip collection port 23a opens and closes. The drive device is configured to be remotely controlled from the outside of the casing 10.

  Thus, the sampler sampling port handling device 40 opens and closes the tip end sampling port 23a of the sampler 23, and has the sampler presser 41 that is fixed to the sampler sampling port handling device 40 and presses the main pipe 14 of the sampler 23. .

  The driving device 30 a, the electric shutter 13, the sample container handling device 31, and the sampler sampling port handling device 40 are configured so that they can be remotely operated from the outside of the casing 10.

  Sampling of the radioactive powder collected and retained in the residue collection container 5 is performed as follows. That is, the isolator 21 and the electric shutter 13 are closed, the exhaust device 26 is driven to make the inside of the casing 10 have a negative pressure, and then Ar gas is injected into the casing 10 through the Ar gas introduction line 25 and the atmosphere in the casing 10 is Is replaced with Ar gas. After the replacement, the driving of the exhaust device 26 is stopped, and the pressure gauge P is used to monitor the pressure in the casing 10 to be higher than the pressure inside the residue collection container 5. Apply feedback control to make it so.

  In this way, with the pressure in the casing 10 maintained so as to be higher than the pressure inside the residue collection container 5, the isolation device 21 is opened, and then the drive device 30a is driven to connect the drive device 30a itself to the rail. Lower along 30b. As a result, the sampler sampling port handling device 40 is also lowered, so that the sampler 23 passes through the guide tube 22 downward, and finally the lower end of the sampler 23 is radioactive in the residue collection container 5 as shown in FIG. It is inserted into the powder.

  Thereafter, the sampler sampling port handling device 40 is driven to push the sampler tip sampling port support bar 23b downward, and the sampler tip sampling port 23a is opened as shown in FIG. The sampler tip collection port 23a is closed. If it does in this way, radioactive powder can be stored between the main 14 and the constriction of the top 15.

  Next, the driving device 30 a is driven in the reverse direction to raise the sampler sampling port handling device 40 together with the sampler 23 together with the driving device 30 a, and the sampler 23 is accommodated in the casing 10. After that, the isolating device 21 is closed and the inside of the casing 10 and the inside of the residue collection container 5 are partitioned so that the two are isolated from each other.

  At this time, if there is a situation where the radioactive powder or atmosphere in the residue collection container 5 seems to have entered the casing 10, the exhaust device 26 is driven to exhaust them and send them to the exhaust processing side. .

  Next, the sample container handling device 31 is driven to horizontally rotate the arm 12 on which the sample container 32 is mounted, so that the sample container 32 is positioned below the lower end of the sampler 23. Next, the sampler sampling port handling device 40 is driven to open the sampler tip end sampling port 23a as shown in FIG. 5B, and the radioactive powder stored between the main pipe 14 and the top 15 is stored. Into the sample container 32.

  After receiving the radioactive powder in the sample container 32, the electric shutter 13 is opened, the arm 12 is rotated, and the sample container 32 is moved to the sample container transport device 11 and delivered. Thereafter, the arm 12 is rotated back into the casing 10, the electric shutter 13 is closed to return the inside of the casing 10 to a sealed state, and the supply of Ar gas into the casing 10 is also stopped.

Since the embodiments of the present invention are as described above, the embodiments of the present invention have the following features (1) to (5).
(1) In a sampling apparatus that performs sampling from a powder container in which radioactive powders of non-volatile U, Pu, and FP are retained in a fluorination step that is a fluorine atmosphere, the powder container and the sampling apparatus are separated from each other. It shall have an isolation device as possible. This isolation device is “open” when sampling the powder in the powder container, and “closed” after the sampling is completed. By having this isolation device, it is possible to isolate the powder container that is a fluorine atmosphere and the sampling device that is not a fluorine atmosphere.
(2) In the sampling device having the contents of the above (1), in order to keep the pressure in the sampling device higher than the pressure in the powder container, it has an Ar gas introduction line, a pressure gauge, and a pressure regulating valve. To do. As a result, Ar gas flows from the sampling device to the powder container even if the isolation device is “open” during powder sampling, in which the sampler is inserted and withdrawn from the sampling device, so that gas leaks from the powder container in a fluorine atmosphere. Can be prevented.
(3) In the sampling device having the contents of the above (1), an exhaust device is provided so that the inside of the sampling device can be replaced. As a result, when the sampler is inserted and withdrawn from the sampling device, the sampling device is replaced with Ar gas even if gas is flowing into the sampling device from the powder container in a fluorine atmosphere when the isolation device is “open”. it can.
(4) In the sampling device having the contents of the above items (1) to (3), a sampler insertion device for inserting and extracting a sampler for sampling radioactive powder into a powder container, and a sampling port at the tip of the sampler. It shall have a sampler sampling port handling device that opens and closes. By having a sampler insertion device and a sampler sampling port handling device, an operator does not have to sample radioactive powder from a powder container in a fluorine atmosphere manually.
(5) In the sampling device having the contents of the above items (1) to (4), a sample container for collecting the radioactive powder collected by the device of (4) and a sample for discharging the sample container from the sampling device It shall have a container handling device. Having a sample container handling device eliminates the need for an operator to handle a sample container from which radioactive powder has been manually collected.

According to the present embodiment, in sampling the non-volatile U, Pu and FP fluoride radioactive powder from the fluorination step which is a fluorine atmosphere, the isolation function, the fluorine atmosphere and pressure management function, and the replacement function by the discharge device are provided. By providing a sampling device having the above, it is possible to prevent leakage of fluorine gas and radioactive material to the outside of the fluorine atmosphere system, and moisture is mixed into the fluorine atmosphere system and HF is generated by reaction with F ₂ gas. Material corrosion due to HF can be prevented.

  INDUSTRIAL APPLICABILITY The present invention is applicable to a powder sampling apparatus for sampling radioactive powder residue and the like generated in the process of reprocessing spent nuclear fuel.

1 powder feed line 2 Ar gas supply line 3 F ₂ gas supply line 4 frames furnace 5 remaining渣回container 6 UF ₆ gas refining line 7 residue recovery line 8 residue conveying device 10 casing 20 sampling device 21 isolation device 22 the guide tube 23 Sampler 23a Sampler tip collection port 23b Sampler tip collection port support rod 24 Pressure regulating valve 25 Ar gas introduction line 26 Exhaust device 30 Sampler insert device 30a Sampler insert device drive device 30b Rail 30c Guide 31 Sample container handling device 32 Sample container 40 Sampler Sampling port handling device 41 Sampler holder P Pressure gauge

Claims (4)

It provided for the powder container for retention of radioactive powder nonvolatile fluoride generated in reprocessing of spent nuclear fuel, a sampling device for collecting the radioactive powder of the powder in the container ,
An isolating device for isolating and communicating between the inside of the casing surrounding the outline of the sampling device and the inside of the powder container;
And injection means for the inert gas into said casing,
Pressure adjusting means for making the pressure in the casing higher than the pressure in the powder container;
A powder sampling device with   2. The powder sampling apparatus according to claim 1, wherein an exhaust device for exhausting the inside of the casing is connected to the casing. In Claim 2, the casing has a guide tube that communicates with the powder container,
The sampling device includes a sampler disposed on an extension of the guide tube, a sampler insertion device that drives the sampler to be inserted into the powder container and pulled out from the powder container through the guide tube, A powder sampling device comprising: a sampler sampling port handling device that opens and closes a sampler tip sampling port of a sampler. The sample container handling device according to claim 3, wherein a sample container for collecting the radioactive powder sampled in the casing is moved out of the casing and discharged.
Opening and closing means for opening and closing a part of the casing serving as the discharge movement path.

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