JP5651380B2 - Method and apparatus for treating radioactive solid waste - Google Patents

Description

  The present invention relates to a method and apparatus for treating radioactive solid waste, and more particularly to a method and apparatus for filling a waste container filled with radioactive solid waste with a filler.

  As solid radioactive waste generated from nuclear facilities and the like, there are metal wastes such as channel boxes and hulls which are activated by long-term neutron irradiation and have a high radionuclide concentration. There are also non-combustible wastes other than metals such as concrete and filters.

  A treatment method for these solid radioactive wastes is currently being studied, but has not yet reached a practical stage. In general, cement solidification, glass solidification, melt solidification, and the like are assumed as a solidification treatment method for forming a radioactive waste waste. Among these, since the cement solidification method is inexpensive and easy to process, application to solidification of many wastes is assumed (for example, refer to Patent Document 1).

  However, if the concentration of radionuclide contained in the radioactive waste is high, there is a concern that the pore water or crystallization water present in the filled cement solidified material is decomposed by radiation and generates a radiolytic gas. . In order to suppress the release of gas from the solidified container, it is conceivable to seal the container, but there is a concern that the internal pressure will increase during long-term storage.

  On the other hand, there is a report of a method of filling a container containing solid radioactive waste with sand to make a waste (see Non-Patent Document 1).

  In this report, (1) When radioactive waste is buried in a disposal container, measures are taken so that no voids remain after the embedding is completed so that the upper cover soil is not affected by the collapse of the waste. It is described that it is required from the burial rule to do so, and (2) the concept of treating the voids by vibrating and filling the waste container with sand is considered.

Japanese Patent Laid-Open No. 2003-307592

Japan Atomic Energy Society Spring 2009 Annual Meeting (D56) “Sandy soil filling confirmation test in waste storage container”

  In order to keep the gap between radioactive solid waste and the waste container as a filler, and to maintain the gap in the container at a certain level, the entire waste container is vibrated and dense. It is desirable to fill.

  Sensors that detect the completion of filling so that no voids remain in the waste container are desirable to avoid degradation due to wear from friction with the filler and the effects of radiation from radioactive waste. An electronic component such as a sensor for detection is desired to be installed at a position away from the radioactive waste, that is, outside the waste container and detected.

  On the other hand, the shape of the radioactive solid waste is unspecified, and if a powder such as sand is used as a filler, a gap may be formed between the radioactive solid waste and the filler after filling. For this reason, unlike the case of filling with liquid cement, the remaining void in the disposal container cannot be managed only by the apparent height of the filler.

  The present invention has been made to solve the above-mentioned problems, that is, it is less affected by wear and radiation deterioration due to vibration, can detect the completion of filling of the filler with high reliability, and has a void amount in the waste container. It is an object of the present invention to provide a radioactive solid waste processing method and apparatus capable of accurately managing the above.

In order to achieve the above-mentioned object, the radioactive solid waste processing method of the present invention includes a waste charging step of charging radioactive solid waste into a waste container, and the inside of the waste container after the radioactive solid waste is charged. comprising of a gap evaluation step of determining the void volume, based on the void volume calculated, the filling material filling step of filling a filler consisting of granules was in a gap of the solid waste in the waste container, the said In the filler filling step, the filler volume evaluation step for determining the volume of the filler to be injected based on the void volume evaluated in the void evaluation step, and the filling by the injection pipe based on the determined volume of the filler A filler injecting step for injecting a material, a filling completion detecting step for detecting completion of the filling of the filler, and an excitation for densely filling the waste container with the filler by vibrating the waste container When the injection of the filler is stopped, the amount of the filler remaining in the injection pipe is obtained, and the waste container is moved by moving the position of the inner lid that closes the waste container according to the remaining amount. And a step of increasing the volume .

The filling material filling apparatus according to the present invention includes a filling material storage container for storing a filling material and a disposal container connected by an injection pipe, and the injection pipe includes an injection control device for controlling an injection amount, and filling is completed. And a vibration detecting device for vibrating the waste container is installed at the bottom of the waste container, and the waste container has a filling material remaining in the injection pipe. According to the quantity, the volume increasing means which can increase the volume of the said waste container by moving the position of the inner lid which closes the said waste container is provided .

  According to the present invention, when filling a waste container filled with radioactive solid waste, it is possible to detect the completion of filling of the filler with high reliability, and to reduce the influence of wear due to vibration and radiation deterioration. Can do. In addition, the volume filling rate of the filler can be accurately managed.

The flowchart explaining the processing process of one Embodiment of the radioactive solid waste processing method which concerns on this invention. The flowchart explaining the specific process sequence of the space | gap evaluation process of FIG. The flowchart explaining the other process sequence of the space | gap evaluation process of FIG. The schematic diagram which shows the structural example of the apparatus which implements the space | gap evaluation process of FIG. The schematic diagram which shows the structural example of the apparatus which implements the filler filling process of FIG. The flowchart explaining the specific process sequence of the filler filling process of FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a flowchart for explaining the processing steps of an embodiment of the radioactive solid waste processing method according to the present invention.

  In this treatment method, first, the radioactive solid waste 1 is put into the waste container 2 (waste throwing step S3).

  Next, the void volume other than the radioactive solid waste 1 in the waste container 2 is obtained (void evaluation step S4).

  Further, a filler 5 is filled in the gap between the solid wastes 1 in the waste container 2 (filler filling step S6). The filler 5 may be a granular material that is not decomposed by radiation, such as sand, alumina, silicon nitride, silica, and metal particles, and a plurality of particle sizes and materials may be mixed.

  Next, as an example of a specific processing procedure for the gap evaluation step S4, a gap evaluation step S4a is shown in FIG.

In the void evaluation step S4a of FIG. 2, after putting the radioactive solid waste 1 into the waste container 2, the total weight W _t of the waste container 2 is measured, and the weight W _v of the waste container 2 known in advance is calculated as the total weight. By subtracting from the weight, the weight W _r of only the radioactive solid waste 1 is calculated (input weight evaluation step S7).

  Next, since the material of the radioactive solid waste 1 is known in advance by the original application site, the average density ρ of the material is obtained (average density evaluation step S8).

Further, the volume V _r of the radioactive solid waste 1 introduced from the obtained average density and weight is evaluated (volume evaluation step S9).

Then, the equation (1), the volume of the radioactive solid waste 1 obtained in a volume evaluation process S9, subtracted from the internal volume V _v of waste container 2, determining the volume V ₀ which voids within disposal container 2 (wt Formula void volume evaluation process S10).

V ₀ = V _v −V _r = V _v − (W _r / ρ) (1)
_{(However, W r = W t -W v} ) (V 0: volume of air gap, _{V v:} internal volume of the waste container 2, _{V r:} volume of radioactive solid waste 1, _{W r:} radioactive solid waste 1 Weight, W _t : Total weight of waste container 2 and radioactive solid waste 1, W _v : Weight of waste container 2)
Further, from the void volume V ₀ in the container, the volume of the filler 5 to be filled necessary for achieving the target filling rate is obtained (filler filling amount evaluation step S11).

That means
Filler volume = filling rate x void volume in container V ₀
It is.

  FIG. 3 shows another specific processing procedure for the gap evaluation step S4.

In the void evaluation step S4b of FIG. 3, the waste container is structured to be airtight, the volume of the void is assumed to be V _0, and the initial pressure P ₀ in the waste container is recorded (initial pressure monitoring step S12). At this time, the pressure after the inside of the container is evacuated to a negative pressure or a vacuum state from the atmospheric pressure can be set to the initial pressure P ₀ .

Next, the volume V ₁ and pressure P ₁ of the sealing gas are evaluated (sealing gas evaluation step S13).

Then, by injecting the encapsulating gas to a waste container 2, to monitor the pressure P ₂ after the injection (sealed after pressure monitoring step S14).

  From these parameters, the relationship of the following equation (2) is established before and after the sealing gas is injected into the waste container 2.

P ₀ V ₀ + P ₁ V ₁ = P ₂ (V ₀ + V ₁ ) (2)
(Where V _{0 is} the volume of the void in the waste container 2, P _{0 is the} initial pressure, P _{1 is} the pressure of the sealing gas, V _{1 is} the volume of the sealing gas, and P _{2 is the} sealing gas. Pressure after injection into)
Thus, the void volume V ₀ is

It becomes. Accordingly, the volume V ₀ of the void in the waste container 2 is obtained using Equation 3 (pressure type void volume evaluation step S15).

  FIG. 4 shows a configuration example of an apparatus that performs the gap evaluation step S4b.

  In this apparatus, an exhaust pump 18 as an exhaust means for exhausting the gas inside thereof is connected via an exhaust valve 19 to a sealed container 16 that accommodates the entire waste container 2 into which the radioactive solid waste 1 is charged. Furthermore, a waste container internal pressure monitor 20 is provided as pressure measuring means for measuring the internal pressure of the sealed container 16. A sealed gas sealed container 23 filled with a sealed gas 21 is connected to the sealed container 16 via a sealed gas sealed valve 22. Further, the pressure of the sealing gas 21 can be measured by a sealing gas pressure monitor 24 as a sealing gas pressure measuring means connected to the sealing gas sealed container 23.

  Using this apparatus, first, the radioactive solid waste 1 is put into the waste container 2, and then the waste container 2 is stored in a sealed container 16 whose volume is clear and airtight. In addition, when gas can be sealed in the disposal container 2 by the inner lid 17 of the disposal container 2, the sealed container 16 can be omitted.

Next, after the gas inside the sealed container 16 is exhausted by the exhaust pump 18 and the exhaust valve 19 is closed, the pressure in the sealed container 16 is measured by the waste container pressure monitor 20, and the initial pressure P ₀ is measured. And

Further, the volume V ₁ and pressure P ₁ of the sealing gas 21 are evaluated in the sealing gas evaluation step S13. These are, in the state where the encapsulating gas 21 is sealed to the sealed gas the sealed container 23 at sealed gas sealing valve 22, the pressure P ₁ is at sealed gas pressure monitor 24, the volume V ₁ was sealed gas Evaluation is based on the internal volume of the sealed container 23.

Next, in the post-sealing pressure monitoring step S <b> 14, the sealing gas sealing valve 22 is opened and the sealing gas 21 is injected into the sealed container 16. The pressure after the injection is measured by the waste container pressure monitor 20 after the sealing gas sealing valve 22 is closed, and is set as the pressure P ₂ after the injection.

Further, in the pressure type void volume evaluation step S15, the void volume V ₀ is obtained using Equation 3. In this embodiment, since the sealed container 16 having a clear volume is used in advance, the volume ratio in the waste container 2 is corrected to the volume in the waste container 2 and then the expression 3 is applied to the waste container 2. The void volume V ₀ is determined.

  In response to this result, in the filler filling amount evaluation step S11, the necessary volume of the filler to be injected for filling is calculated.

  Next, FIG. 5 shows a configuration example of a filling apparatus that performs the filler filling step S6.

  In this filling device, the filling material storage container 26 in which the filling material 5 is accommodated and the disposal container 2 are connected by an injection pipe 27, and an injection control device 28 for controlling the injection amount is provided in the injection pipe 27. Further, a completion detection sensor 29 for detecting completion of filling is provided in the vicinity of the disposal container 2 of the injection pipe 27.

  Further, the waste container 2 is provided with a variable position inner lid retainer 31 as a volume increasing means so that the position of the inner lid 17 can be moved upward according to the amount of the filler 5 remaining in the injection pipe 27. It has been. The variable-position inner lid retainer 31 includes, for example, a pressure spring 31a that is urged on the lower surface of the inner lid 17, and a fastener 31b that is movably hooked on the inner surface of the waste container 2 and above the inner lid 17. And can be configured.

  In addition, a vibration device 30 that vibrates the waste container 2 is installed at the bottom of the waste container 2 in order to perform reliable filling.

  A specific process for performing the filler filling process S6 using this filling apparatus will be described with reference to FIG.

First, based on the void volume V ₀ obtained in the void evaluation step S4, it determines the filler amount to be injected (filler volume evaluation step S32). Theoretically, filling can be completed by injecting this amount of filler, but in reality, it may be impossible to inject into the gap depending on the shape of the radioactive solid waste 1, etc. Means for detecting the above are provided.

  Therefore, first, the injection control device 28 is opened, and the filler 5 is injected into the waste container 2 via the injection pipe 27 (filler injection step S33).

  When the filler 5 is clogged up to the injection pipe 27, the completion of the injection is detected by the completion detection sensor 29 that detects the presence or absence of the filler in the pipe (filling completion detection step S34).

  As the completion detection sensor 29, a radiation type sensor due to a difference in radiation permeability due to a density change in the pipe, an ultrasonic sensor due to a difference in ultrasound permeability, a capacitance sensor that detects a change in electrical capacitance, and the like. Can be used.

  Further, in order to ensure detection by these sensors, it is preferable that the injection controller 28 controls the injection amount of the filler 5 to be reduced when the filler 5 is almost near the completion of the injection. For example, the above-mentioned radiation sensor is used as the completion detection sensor 29 to monitor the density in the injection pipe 27 at the time of injection, and the injection control device 28 reduces the injection amount of the filler 5 based on the change in density. To control.

  When filling completion detection 34 is performed, the injection is stopped. Then, it vibrates with the vibration apparatus 30, and the filling material 5 is densely filled into the waste container 2 (vibration process S35).

  At the start of filling, since the gap in the waste container 2 is still large, the filler 5 is injected into the waste container 2 by vibration, and the completion detection signal of the completion detection sensor 29 is reset. When reset, as shown in FIG. 6, the filling material injection step S33, the filling completion detection step S34, and the vibration step S35 are repeated. Note that the amount of filler 5 that can be newly injected with vibration decreases as the number of repetitions of this flow increases. Therefore, the vibration time for the number of repetitions is adjusted to a value calibrated in advance in a preliminary test or the like. (Vibration time evaluation process S36).

  If the filling completion detection signal is not reset even if the vibration is continued, it can be determined that a sufficient amount has already been filled.

  Here, in the filling apparatus according to the present embodiment, in consideration of the radiation resistance of the sensor, the completion detection sensor 29 is not provided inside the disposal container 2 but is installed at a position outside the disposal container 2. Therefore, a large amount of filler 5 may remain in the injection pipe 27. That is, since the filler 5 remains in the injection pipe 27 from the installation position of the completion detection sensor 29 to the disposal container 2 or from the installation position of the injection control device 28 to the disposal container 2, the injection pipe 27 is separated from the disposal container 2. At this time, the filler 5 may be scattered.

  For this reason, in the filling device of the present embodiment, at the final stage of filling, the position of the inner lid 17 is moved upward according to the amount of the filler 5 remaining in the injection pipe 27. 31 (volume increasing means) is provided.

  Accordingly, the inner lid 17 is moved upward to increase the internal volume of the waste container 2 by the amount of filler 5 remaining in the injection pipe 27 (inner lid moving step S37), and finally shaken and filled (final addition). Shaking step S38). This final vibration time can also be adjusted so that most of the filler 5 remaining in the injection pipe 27 can be stored in the waste container 2 by using a value which is previously evaluated by a test or the like in the vibration time evaluation step S36.

  As described above, according to the present embodiment, it is possible to estimate the amount of the filler 5 by evaluating the void space in advance, and based on this, the filler 5 is injected, so that the injection can be efficiently performed without waste. It can be carried out.

  In addition, the injection speed can be reduced near the completion of the injection of the filler 5, and accordingly, even if the completion detection sensor 29 is installed at a position away from the waste container 2, the filling in the injection pipe 27 is ensured. The presence / absence of the material 5 can be detected, and the amount of the filler 5 injected from the detection to the injection stop and remaining in the injection pipe 27 can be reduced.

  As a result, the completion detection sensor 29 can be installed at a position away from the waste container 2, the influence of radiation from the radioactive solid waste 1 can be reduced, and the filler 5 in the injection pipe 27 can be detected without contact. Also, wear of the completion detection sensor 29 can be prevented by vibration.

  Further, in order to reliably inject the filler 5 remaining in the injection pipe 27 into the waste container 2 after detection of the completion of filling, a variable position inner lid retainer 31 that can move the position of the inner lid 17 is provided. Thus, the filler 5 does not scatter when the injection pipe 27 is separated from the disposal container 2, and a highly reliable filling device for the filler 5 can be provided.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. Processes S4a and S4b can be used in combination.

  Further, the sealing of the disposal container 2 has been described as using the inner lid 17, but an outer lid that covers the upper surface of the disposal container 2 may be used. In that case, for example, an O-ring is used to secure airtightness on the upper surface of the side wall of the waste container 2 or the contact surface of the outer lid with the waste container 2. The outer lid may be fixed by, for example, a fixing device attached to the outside of the waste container 2, or simply placed on the waste container 2 and sealed inside the waste container 2 by its own weight.

  Further, the calculation processing and the like performed in the evaluation process described above can be performed by incorporating software in a general-purpose computer or by dedicated hardware.

  1: radioactive solid waste, 2: waste container, S3: waste charging step, S4: void evaluation step, 5: filler, S6: filler filling step, S7: input weight evaluation step, S8: average density evaluation step S9: Volume evaluation step, S10: Weight type void volume evaluation step, S11: Filler filling amount evaluation step, S12: Initial pressure monitoring step, S13: Gas evaluation step for sealing, S14: Pressure monitoring step after sealing, S15: Pressure type void volume evaluation process, 16: sealed container, 17: inner lid, 18: pump for exhaust, 19: valve for exhaust, 20: pressure monitor for waste container, 21: gas for sealing, 22: gas sealing valve for sealing , 23: Sealed gas sealed container, 24: Filled gas pressure monitor, 26: Filler storage container, 27: Injection pipe, 28: Injection control device, 29: Completion detection sensor, 30: Excitation device, 31: Variable Position inner lid Even 31a: pressure spring, 31b: fastener, S32: filler volume evaluation process, S33: filler injection process, S34: filling completion detection process, S35: vibration process, S36: vibration time evaluation process, S37: internal Lid moving process, S38: Final excitation process

Claims (7)

A waste charging process for charging radioactive solid waste into a waste container;
A void evaluation step for determining a void volume in the waste container after the radioactive solid waste is charged;
Based on the calculated void volume, a filler filling step for filling a gap between the solid waste in the waste container with a filler made of a granular material,
Equipped with a,
The filler filling step includes
Based on the void volume evaluated in the void evaluation step, a filler volume evaluation step for determining the volume of the filler to be injected, and
A filler injection step of injecting a filler through an injection pipe based on the volume of the determined filler;
A filling completion detection step of detecting completion of filling of the filler;
An oscillating step of densely filling the waste container with the filler by vibrating the waste container;
When the injection of the filler is stopped, the amount of filler remaining in the injection pipe is obtained, and the volume of the waste container is increased by moving the position of the inner lid that closes the waste container according to the residual amount. Increasing the process;
The radioactive solid waste processing method characterized by having . The void evaluation step includes
An input weight evaluation step for measuring the weight of the radioactive solid waste,
An average density evaluation step for evaluating an average density of the radioactive solid waste;
A volume evaluation step for evaluating the volume of the radioactive solid waste from the weight and average density of the radioactive solid waste;
A weight-type void evaluation step for evaluating the void volume by subtracting the volume of the evaluated radioactive solid waste from the volume of the waste container;
The radioactive solid waste processing method of Claim 1 characterized by the above-mentioned. The void evaluation step includes
Monitoring the initial pressure in the waste container;
Evaluating the volume and pressure of the encapsulating gas;
Injecting the sealing gas into the waste container and monitoring the post-injection pressure monitoring step for monitoring the pressure after the injection;
A pressure type void volume evaluation step for evaluating the volume of the void from the volume and initial pressure of the waste container, the volume and pressure of the sealing gas, and the pressure after injecting the sealing gas into the waste container;
The radioactive solid waste processing method of Claim 1 characterized by the above-mentioned. 4. The method according to claim 1, wherein the filling material injection step, the filling completion detection step, and the vibration step are repeated until the filling of the filling material into the waste container is completed. The radioactive solid waste processing method as described. The radioactive solid waste processing method according to any one of claims 1 to 4, wherein the filler is sand . A filling material storage container for storing the filling material and a disposal container are connected by an injection pipe, and the injection pipe is provided with an injection control device for controlling the injection amount and a completion detection sensor for detecting the completion of filling, At the bottom of the waste container, a vibration device for vibrating the waste container is installed.
  The waste container is provided with a volume increasing means that can increase the volume of the waste container by moving the position of the inner lid that closes the waste container according to the amount of filler remaining in the injection pipe. Have
A filling material filling apparatus. The volume increasing means is composed of a pressure spring biased to the lower surface of the inner lid, and a fastener that is movably hooked on the inner surface of the waste container and above the inner lid. The filling material filling apparatus according to claim 6.

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