JP3115478B2 - Equipment and method for solidifying radioactive waste pellets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for solidifying various radioactive wastes generated from a nuclear power plant and the like. And a method for solidifying radioactive waste pellets solidified in a solidification container.

[0002]

2. Description of the Related Art Nuclear power plants and the like generate a considerable amount of waste containing radioactive nuclides, which are safely stored in facilities in drums or the like, or solidified solidified. It is also stored within the facility as a body. The solidified solid is mainly a liquid waste that is kneaded with a solidifying material such as cement and solidified, and solid waste, for example, liquid waste is dried and powdered and pressed into pellets. Most of pellets, used ion exchange resins, miscellaneous solids, and the like are stored and stored in facilities without being solidified.

With respect to low-level waste generated from a nuclear power plant, a method of burying and managing the buried waste in a shallow stratum has been embodied in recent years. ing. When burying in shallow formations, liquid waste is dried and pulverized and pressed into pellets, and pellets and solidified waste ion exchange resin are also buried. Can be buried in the same manner as a solidified body obtained by solidifying the above.

A conventional technique for solidifying pellet-like waste (waste pellets) is disclosed in Japanese Patent Application Laid-Open No. 57-93299.
There is one described in Japanese Patent Publication No. In this method, pellet-like waste is filled in a container, and water glass is injected as a liquid solidifying material from an upper opening of the filling container.

[0005] Further, as a conventional technique for preventing uneven distribution of pellets in a solidified body during solidification of waste pellets, there is a method described in JP-A-60-238800. This involves using a solidified material having a specific gravity greater than that of the waste pellets, injecting a predetermined amount of the solidified material into the solidification container as the first stage, then charging the waste pellets, and then, as a second stage, placing the solidified material on top of the solidified material. This is a solidification method in which waste pellets are maintained near the center of the solidified body.

As another method for preventing uneven distribution of waste pellets in a solidified body, the specific gravity of the solidified material is adjusted as described in JP-A-63-167297 and JP-A-3-189600. There is a way to do that. These methods are
For example, a lightweight aggregate or sand is added to a solidified material such as cement to adjust the specific gravity of the paste of the solidified material to prevent the pellets from floating.

On the other hand, a plastic solidification method using a thermosetting resin as a solidifying material is known. In this solidification method, as a method for preventing sedimentation of radioactive waste until the thermosetting resin gels, Japanese Patent Publication No. Sho 60-17080. There is one described in Japanese Patent Publication No. This means that when solidified liquid or slurry waste is solidified using a thermosetting resin, the amount of radioactive filler equivalent to the difference between the planned and actual input amounts of radioactive waste For example, silica sand is filled to prevent settling of waste.

[0008]

As described above, as for low-level waste generated from a nuclear power plant, a method of burying and managing the waste in a shallow stratum has been embodied. The embedding of the solidified solid has been implemented.
In the case of these burials, evaluations have been carried out in consideration of sufficient safety factors, and it has been evaluated that they are safe. Conditions such as performance or material are required. For example, with respect to the solidified waste, it is required that the waste containing a radionuclide is solidified uniformly without being unevenly distributed only in a part.

When the waste is in a liquid state, the solid is usually formed by mixing the liquid waste with a solidifying material such as cement, so that the waste is uniformly dispersed in the solid and becomes a problem. No.

However, when the waste is solid, such as pellets, the dispersion of the waste in the solidified body depends on the type of the solidifying material used, the type of the solid waste, and the amount of the filled waste. It is expected that the degree will be different. For example, when the waste is a pellet, the main component of the pellet differs depending on the type of the waste before being formed into a pellet, and the specific gravity of the pellet varies accordingly. If the specific gravity of the pellet is larger than the solidified material, the pellet will settle to the bottom of the solidified material. Conversely, if the specific gravity is small, it will float above the solidified body. When the filling amount of the pellets is large, the pellets interfere with each other, and such sedimentation and lifting do not cause much problem. However, there are cases where the filling amount must be reduced due to limitations on the surface dose rate of the solidified body, etc., in this case, sedimentation or lifting of the pellet becomes remarkable, and a part of the solidified body,
For example, pellets are unevenly distributed only at the bottom and upper portions of the solidified body.

In the prior art described in Japanese Patent Application Laid-Open No. 57-93299, the solidifying material paste to be injected is non-radioactive, and the kneading machine for preparing the solidifying material paste is also non-radioactive. And there is an advantage that maintenance becomes easy. However, when the specific gravity of the pellet-like waste and the solidified material is significantly different, the problem that the pellets are unevenly distributed as described above occurs when the amount of the waste is small.

In the prior art described in Japanese Patent Application Laid-Open No. 60-238800, the solidified material is injected in two stages and the waste pellets are held near the center of the solidified body. Or, uneven distribution at the bottom can be avoided. However, since the waste pellets are not dispersed, the pellets are still unevenly distributed even in the center.

In the prior arts described in JP-A-63-167297 and JP-A-3-189600, the specific gravity of the paste of the solidified material is adjusted by adding a lightweight aggregate to prevent the pellets from floating. I have. In this method, it is relatively easy to increase the paste specific gravity of the solidified material,
There is a problem that it is difficult to reduce the specific gravity. Also,
When the difference between the specific gravity of the paste of the solidified material and the specific gravity of the pellets is large, there is a problem that it is difficult to adjust the specific gravity. When one type of pellet is selected from several types of waste pellets having different specific gravities to be solidified, it is necessary to change the specific gravity of the solidified material according to the type of the waste pellet. For this reason, there is a problem that the solidification treatment equipment becomes complicated and the operation becomes complicated and difficult.

In the prior art described in Japanese Patent Publication No. Sho 60-17080, a radioactive filler is added to a thermosetting resin in an amount corresponding to the difference between the planned input amount of radioactive waste and the actual input amount. To prevent sedimentation of waste. However, when solidifying waste pellets using this technique, silica sand having a much smaller particle size than the pellets is used as a filler, and therefore, uneven distribution of the pellets cannot be prevented with silica sand. In addition, since the specific gravity of the pellets is different when the type of the pellet is different, even if the same weight of the pellet is put into the solidification container, the bulk volume of the pellet in the solidification container is different when the type of the pellet is different, and the pellet is uniform in the solidified body. The weight of the filler required to disperse the particles in the mixture also differs. For this reason, different types of pellets cannot be solidified in a uniformly dispersed state in the same facility.

An object of the present invention is to provide a radioactive waste pellet solidification treatment facility and a treatment method which can solidify even different kinds of waste pellets in a uniformly dispersed state using the same equipment. It is in.

[0016]

Means for Solving the Problems In order to achieve the above object, the waste pellet solidifying equipment of the present invention adopts the following constitution. That is, in a solidification processing facility for radioactive waste pellets in which radioactive waste is dried and powdered and the pellets obtained by compression-molding the radioactive waste in a solidification container using a solidifying material, a plurality of pellet storages in which different types of pellets are stored. A container, a solid substance storage container in which a solid substance having the same size as the pellet is stored, and pellets and solid substance transferred from the pellet storage container and the solid substance storage vessel, and these are mixed. A first kneading tank for stirring and charging the solidified container, a pellet transfer unit for measuring each pellet from the plurality of pellet storage containers and transferring the pellet to the first kneading tank, and the solid substance storage container A solid substance transfer means for measuring a solid substance and transferring it to the first kneading tank, and selecting one type of pellet from the different types of pellets First transfer control means for controlling the pellet transfer means so that the selected predetermined weight of pellets is transferred to the first kneading tank; and solidifying the pellets selected by the first transfer control means. The target weight of the solid substance necessary for uniformly dispersing and solidifying in the container is obtained, and the solid substance transfer means is so arranged that the target weight of the solid substance is transferred to the first kneading tank. e Bei a second transfer control means for controlling said second transfer
The feeding control means is provided for each of the different types of pellets.
The pellet weight and the pellets evenly in the solidification vessel.
Remembers the correlation with the weight of solid substances required for dispersion and solidification
And transferred to the first kneading tank based on the correlation.
Solid material weight corresponding to the given weight of pellets sent
The a structure in which Ru determined as the target weight of the solid material.

[0017]

[0018]

Further, the solidification processing equipment is preferably
The apparatus further comprises a first operating means for inputting a numerical value of a target uniformity of the dispersion of the pellets in the solidification vessel, and wherein the second transfer control means sets a target of the solid substance so as to obtain the target uniformity. Calculate the weight.

[0020] Further preferably, the above-mentioned solidification treatment equipment comprises:
A second operation means for instructing selection of any one of the different types of pellets, wherein the first transfer control means transfers the first kind of pellets to the first kneading tank in response to a selection signal from the second operation means. Select the type of pellet to be used.

[0021]

The solidification treatment equipment further comprises a solidified material storage container and a water storage container for storing the solidified material and the added water, respectively, and the solidified material and the added water transferred from the solidified material storage container and the water storage container. A second kneading tank which stirs and mixes the solidified material and transfers the solidified material to the solidification container, and a solidified material which measures the solidified material and water from the solidified material storage container and the water storage container and transfers the solidified material and water to the second kneading container, Water transfer means, so that solidified material and water having a weight corresponding to the predetermined weight of the pellets and the target weight of the solid substance transferred to the first kneading tank are transferred to the second kneading tank. Third transfer control means for controlling the solidifying material and water transfer means may be further provided. In this case, the second transfer control means includes:
For each of the different types of pellets,
Between the pellet weight and the bulk volume in the solidification vessel
First correlation and weight and bulk of the solid substance in the solidification vessel
Includes second correlation with volume, corresponding to the selected pellet
To the first correlation, the second correlation, and the first kneading tank.
Predetermined weight of pellets to be transferred and solidification container for pellets
The target bulk volume required for uniform dispersion and solidification within
The target weight of the solid substance is determined, and the target bulk volume is 70% or more of the volume of the solidification container.

In the solidification treatment equipment, preferably, the first transfer control means includes a dose rate detection means for measuring a surface dose rate of the pellets transferred to the first kneading tank, and the dose rate detection means. Means for stopping the transfer of the pellets to the first kneading tank when the surface dose rate obtained by the means reaches a reference value.

Further, in the above-mentioned solidification treatment equipment, preferably, the pellet transfer means and the solid matter transfer means receive the pellets and the solid matter transferred to the first kneading tank in an intermediate manner, respectively. It has a measuring device for measuring.

The method for solidifying waste pellets according to the present invention employs the following constitution in order to achieve the above object. That is, in the solidification method of radioactive waste pellets in which the radioactive waste is dried and powdered, and the pellet obtained by compression-molding the radioactive waste is solidified in a solidification container using a solidifying material, a solid substance having a size similar to the pellet is used. Is prepared in advance, one type of pellet is selected from different types of pellets, a predetermined weight of the selected pellet is transferred to a kneading tank, and the selected pellet is uniformly dispersed and solidified in the solidification container. Calculating the target weight of the solid material necessary to perform, transferring the solid material of the target weight to the kneading tank, mixing and stirring the pellet and the solid material in the kneading tank, Each procedure of charging into a solidification vessel is adopted.

[0026]

In the solidification method, the solidifying material and the water to be added together with the pellets and the solid substance may be transferred to the kneading tank, mixed and stirred, and then injected into the solidifying vessel.

[0028]

Further, preferably, the front surface dose rate of the pellets to be transported to the kneading tank is measured, <br/> to stop the transport of the pellets to the surface dose rate reaches Then the kneading tank to the reference value You.

[0030]

The reason why the waste pellets are unevenly distributed in the solidified body is that the specific gravity of the pellets is different from that of the solidified material. If the specific gravity of the pellets is larger than that of the solidified material paste, the pellets settle, and if they are small, they rise. The present inventors have found that by adding an appropriate amount of a solid substance having a size similar to that of the pellet to the pellet, the sedimentation or floating of the pellet can be suppressed. This is because if the specific gravity of the pellet is different from that of the solidified material, the pellet tends to settle or float in the solidified material paste, but if a solid material of the same size as the pellet is mixed, the solid material Becomes an obstacle and cannot move,
This is because settling or lifting is suppressed.

In addition, it has been found that when the solid substance is added to suppress the sedimentation or floating of the pellet as described above, the amount of the solid substance to be added must be changed according to the type of the pellet. That is, since the specific gravity of the pellets is different for different types of pellets, the volume of the region occupied by the pellets in the solidification container, that is, the “bulk volume” is not the same even when the pellets of the same weight are charged into the solidification container. For this reason, it is necessary to change the input amount of the solid substance required for suppressing the sedimentation or lifting of the pellet.

The present invention is based on the above findings,
In the solidification treatment equipment of the present invention, the target weight of the solid substance necessary for uniformly dispersing and solidifying the pellets selected by the first transfer control means in the solidification container is determined by the second transfer control means, By controlling the solid substance transfer means so that the target weight of the solid substance is transferred to the first kneading tank, the sedimentation or lifting of the pellets can be appropriately suppressed even for different types of waste pellets. It can be solidified in a uniformly dispersed state using the same equipment.

(A) The uniformity of the dispersion of the pellets in the solidification container is quantitatively grasped by the “bulk volume” of the pellets in the solidification container; be determined in advance the correlation between "bulk volume" in: (c) that is obtained in advance the correlation between "bulk volume" in the weight and solidifying container solid substance; the (d) above (b) Selecting a correlation corresponding to the selected pellet from the correlation, and obtaining a “bulk volume” corresponding to the weight of the pellets transferred to the kneading tank based on the correlation; (e) the target uniformity grasped in (a) above; The “bulk volume” corresponding to the property is set as the target bulk volume, and the difference between the target bulk volume and the bulk volume determined in (d) is calculated; (f) Based on the correlation in (c) above, A solid state corresponding to the difference in the determined bulk volume Determining the weight of the quality as the target weight of the solid material.

(A) The uniformity of the dispersion of the pellets in the solidification container is quantitatively grasped by the “bulk volume” of the pellets in the solidification container; (C) Predetermining the correlation between the weight of the solid substance and the "bulk volume" in the solidification vessel; (d) Selecting a correlation corresponding to the selected pellet from the correlation, and obtaining a “bulk volume” corresponding to the weight of the pellets transferred to the kneading tank based on the correlation; (e) the target uniformity grasped in (a) above; The “bulk volume” corresponding to the property is set as the target bulk volume, and the difference between the target bulk volume and the bulk volume determined in (d) is calculated; (f) Based on the correlation in (c) above, A solid state corresponding to the difference in the determined bulk volume Determining the weight of the quality as the target weight of the solid material.

The correlation between (b) and (c) may be summarized as one correlation between the weight of the pellet and the weight of the solid substance using the bulk volume as a parameter. Here, “bulk volume” refers to the volume of the area occupied in the solidification container by the pellets (or the solid substance or a mixture thereof) put into the solidification container as described above, and the pellet and the pellet (or the solid It is the volume including the gap between the substance and the solid substance or the pellet and the solid substance).

The present invention is also based on the above findings.
In the solidification treatment equipment of the present invention, the seed is used for the second transfer control means.
Pellet weight for each of the different types of pellets
Required to uniformly disperse and solidify the pellets and pellets in the solidification vessel
The correlation with the weight of the solid material is stored
Of a predetermined weight transferred to the first kneading tank based on
The solid state is determined by determining the weight of the solid substance corresponding to
The target weight of the substance is determined.

[0037]

A first operating means for inputting a numerical value of a target uniformity of the dispersion of the pellets in the solidification vessel is further provided, and a target of the solid substance is controlled by the second transfer control means so as to obtain the target uniformity. By calculating the weight, the uniformity can be freely set by the operation of the operator.

[0039]

Further, further providing the second operation means for instructing an arbitrary selection of one of the different types of pellets, the first kneading tank in response to the selection signal from the second operating means in the first transfer control means By selecting the type of pellet to be transferred, the type of pellet can be freely selected by the operation of the operator, and the selected pellet can be solidified in a uniformly dispersed state.

In the above (a), when the uniformity of the pellet dispersion in the solidification container is quantitatively grasped by the “bulk volume” of the pellet in the solidification container, the uniformity of the pellet dispersion and the “bulk volume” of the pellet are determined. Depends on the kneading and solidifying method or the injection and solidifying method. The kneading and solidifying method is a method in which the pellets and the solidifying material are stirred and mixed together in a kneading tank and charged into a solidifying container.In this case, the uniformity of the pellet dispersion and the "bulk volume" are linearly proportional to each other. No (see FIG. 4). Generally, it is said that uniformity is required to be 70% or more in consideration of a sufficient safety factor. In the case of the kneading and solidifying method, the "bulk volume" corresponding to 70% uniformity is 30% of the volume of the solidifying container. Hit the degree. This is about 60 liters when the volume of the solidification container is 200 liters. On the other hand, the injection solidification method is a method in which the pellets are put into a solidification container, and then the solidification material paste is injected into the solidification container. The uniformity of the pellet dispersion and the “bulk volume” are in a linear proportional relationship (see FIG. 10). In this case, the “bulk volume” corresponding to 70% homogeneity corresponds to 70% of the volume of the solidification container, and when the volume of the solidification container is 200 liters, about 1%.
It is 40 liters.

[0042]

In the solidification treatment equipment of the present invention, the second
The transfer control means, said in correlation, the different Perret
Pellets in the solidification vessel for each of the
First correlation between the weight and bulk volume and the solidification vessel
A second correlation between the weight of the solid substance and the bulk volume;
A first correlation corresponding to the pellet obtained, and the second correlation,
A predetermined weight of the pellets transferred to the first kneading tank;
It is configured to determine a target weight of the target KasamiHiroshi product Toka et the solid substance required to uniformly disperse solidified pellet solidifying in the container, by setting the target bulk volume more than 70% of the volume of solidified container , 70% uniformity is achieved.

Further, the first transfer control means is provided with a dose rate detecting means for measuring the surface dose rate of the pellets transferred to the first kneading tank, and the surface dose rate obtained by the dose rate detecting means is set to a reference value. By stopping the transfer of the pellets to the first kneading tank when the temperature has reached, the surface dose rate of the solidified body can be reduced to a reference value or less .

The pellet transfer means and the solid matter transfer means are each provided with a measuring device for receiving the pellets and the solid matter intermediately transferred to the first kneading tank and measuring the weight of the pellets and the solid matter. The substance can be transferred to the first kneading tank while being measured.

Further, the solidification treatment method of the present invention comprises the above (d)
The steps (a) to (f) are carried out so that even if the waste pellets are of different types, the sedimentation or lifting of the pellets is appropriately suppressed, and the pellets are solidified in a uniformly dispersed state using the same equipment. it can.

[0047]

Next, embodiments of the present invention will be described with reference to the drawings. First, a first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the present invention is applied to a kneading-solidification type solidification treatment facility.

In FIG. 1, the solidification processing equipment of the present embodiment has a plurality of pellet storage containers 1a, 1b, 1c for accommodating different types of pellets A, B, C, and has a size similar to the pellets. A solid substance storage container 2 in which the solid substance S is stored, a solidified material storage container 3 and a water storage container 4 in which the solidified material X and the added water Y are respectively stored, and pellets sent from these containers; A kneading tank 6 for mixing and stirring the solidified material, the added water, and the solid substance and charging the solidified container 5.
And a pellet transfer device 7a, 7b, 7c for transferring the pellets A, B, C from the pellet storage containers 1a, 1b, 1c to the kneading tank 6, and a kneading tank for transferring the solid substance S from the solid substance storage vessel 2. Solid substance transfer device 8 for transferring to 6
And valves 9 and 10 for opening and closing pipes for transferring the solidified material X and the added water Y from the solidified material storage container 3 and the water storage container 4 to the kneading tank 6. The kneading tank 6 has a driving device 6
The exhaust pipe is provided with a valve 20 for opening and closing the pipe.

The solidification treatment equipment of the present embodiment comprises a pellet weighing device 11 for receiving the pellets transferred to the kneading tank 6 in an intermediate state and measuring the weight of the pellets. Solid matter measuring device 12 for receiving the solidified material and measuring the weight thereof, solidified material measuring device 13 and the water measuring device 14 for receiving the solidified material and the added water transferred to the kneading tank 6 respectively and measuring the weight thereof. A radiation detector 15 for measuring the surface dose rate of the pellets contained in the pellet weighing device 11; an input key 16a for inputting a numerical value for a target uniformity of pellet dispersion in the solidification container 5; Key 1 for selecting any one of, B, C
6b, an operating device 16 having a display 16c for displaying the content of the input signal of the input key 16a and the content of the selection signal of the selection key 16b;
And control devices 17, 18, and 19 for inputting signals from the operation keys 16a and 16b and controlling the operations of the transfer devices 7a to 7c and 8 and the valves 9 and 10.

Among the control devices 17, 18, and 19, the control device 17 controls the detection signal from the radiation detector 15 and the operation device 1
A selection signal of the selection key 16b from the controller 6 is input to control the driving of the transfer devices 7a to 7c. The control device 18 receives the input signal of the input key 16a from the operation device 16 and the measuring devices 11, 1
2 and a processing signal from the control device 17 to control the driving of the transfer device 8. The control device 19 receives the detection signals from the measuring devices 13 and 14 and the processing signal from the control device 18 and controls the opening and closing of the valves 9 and 10.

In the above, the pellet transfer devices 7a to 7
c and the pellet weighing device 11
The solid material transfer device 8 and the solid material measuring device 12 constitute a pellet transfer means for measuring the pellets A, B, and C from a to 1c and transferring them to the kneading tank 6. And a solid substance transfer means for measuring and transferring the solid substance S to the kneading tank 6.

The method for solidifying waste pellets according to the present invention employs the following configuration to achieve the above object. That is, in the solidification method of radioactive waste pellets in which the radioactive waste is dried and powdered, and the pellet obtained by compression-molding the radioactive waste is solidified in a solidification container using a solidifying material, a solid substance having a size similar to the pellet is used. it to be prepared in advance, and select the one type of pellet from different pellets, transferring the predetermined weight of the selected pellet kneading tank, with each of the different types of pellets
Set the pellet weight and pellet in the solidification container
Phase with the weight of the solid substance necessary for uniform dispersion and solidification
A pellet of a predetermined weight transferred from the Seki to the first kneading tank.
Determining the weight of the solid substance corresponding to the solid, and setting the target weight of the solid substance necessary for uniformly dispersing and solidifying the selected pellets in the solidification container; Are transferred to the kneading tank, and the pellets and the solid substance are mixed and stirred in the kneading tank and charged into the solidification container.

The valve 9 and the solidified material measuring device 13 constitute solidified material transfer means for measuring the solidified material X from the solidified material storage container 3 and transferring the solidified material X to the kneading tank 6, and the valve 10 and the water measuring device 14
Constitutes water transfer means for measuring water from the water storage container 4 and transferring it to the kneading tank 6. The controller 19 controls the solidification material and the water transfer so that the solidified material X and the water Y having the predetermined weight of the pellets transferred to the kneading tank 6 and the target weight of the solid substance are transferred to the kneading tank 6. Means, specifically, third transfer control means for controlling the valves 9 and 10 are constituted.

The pellets A, B, and C contained in the pellet storage containers 1a, 1b, and 1c are obtained by drying and pulverizing radioactive waste and compressing and molding the same. Pellets include concentrated waste liquid pellets and resin pellets. The concentrated waste liquid pellets are obtained by dry-pulverizing concentrated waste liquid mainly composed of a mixture of inorganic salts and iron oxide, and compression-molding the dried waste liquid. Inorganic salts vary depending on the type of power plant, with sodium sulfate being the main component in boiling water power plants and sodium borate in pressurized water power plants. Resin pellets are obtained by drying and powdering ion-exchange resin (granular or powdery) stored in a slurry state, and compression-molding this. These have different specific gravities depending on the main components, and the specific gravities are higher in the order of pellets mainly containing sodium sulfate> pellets mainly containing sodium borate> resin pellets. The pellet A is, for example, a concentrated waste liquid pellet mainly containing sodium sulfate, the pellet B is, for example, a concentrated waste liquid pellet mainly containing sodium borate, and the pellet C is, for example, a resin pellet.

The solid substance may be any substance as long as it has the same size as the pellet, and for example, gravel, crushed stone and the like can be used. In this embodiment, gravel is used.

As the solidifying material, a hydraulic solidifying material which hardens when kneaded with water, more specifically, a cement material is used. In this case, the pellet A containing sodium sulfate as a main component sinks because it is heavier than cement, and the other pellets B and C rise because they are lighter than cement.
The solidifying material is not limited to the cement-based material, and may be any organic material, and may be any solidifying material that does not adversely affect the solidified body by acting on the pellets and the solid substance.

Details of the processing functions of the control device 17 will be described with reference to the flowchart shown in FIG. First, the control device 17 uses the selection key 16b from the operation device 16 to select the pellet A,
The selection signals of B and C and the detection signal from the radiation detector 15 are input (step 100). Next, the operating device 16
, One of the transfer devices 7a, 7b, 7c corresponding to the selected pellet is driven to transfer the selected pellet to the measuring device 11 (step 101). At the same time, based on the detection signal from the radiation detector 15, it is determined whether or not the surface dose rate of the pellets transferred to the measuring device 11 has reached a reference value (Step 102). If the surface dose rate does not reach the reference value, the driving of the transfer device is continued, and if the surface dose rate reaches the reference value, the driving of the transfer device is stopped (step 1).
02). Thereafter, the pellets transferred to the measuring device 11 are automatically sent to the kneading tank 6.

Details of the processing functions of the control device 18 will be described with reference to the flowchart shown in FIG. The control device 18 first receives a pellet selection signal from the operation device 16 using the selection key 16b, a uniformity input signal using the input key 16a from the operation device 16, a pellet weight signal from the weighing device 11, and a signal from the weighing device 12. Solid substance weight signal, control device 1
7 (step 200). Next, the uniformity input based on the input signal of the uniformity from the operating device 16 and the correlation between the uniformity of pellet dispersion and the bulk volume in the solidification vessel 5 shown in FIG. Is set (step 201).

FIG. 4 shows the correlation between the uniformity of pellet dispersion and the bulk volume in the case of the kneading and solidifying method.
The solidification container 5 used had a capacity of 200 liters. As described above, in the kneading and solidifying method, the uniformity of pellet dispersion and the bulk volume are not in a linear proportional relationship. Also, usually
It is said that a uniformity of 70% or more is required in view of a sufficient safety factor, and a bulk volume corresponding to the uniformity of 70% is about 30% of the volume of the solidification container. This is equivalent to 60 liters of the 200 liter solidification container 5.

Next, the pellet weight and bulk volume in the solidification container 5 for each of the different types of pellets A, B, and C shown in FIG. The correlation corresponding to the selected pellet is selected based on the correlation of the above, and based on the correlation and the processing signal from the control device 17, the pellet bulk volume Vp corresponding to the pellet weight when the surface dose rate reaches the reference value is determined. It is calculated (step 202). Next, a difference ΔV = Vt−Vs between the target bulk volume Vt and the pellet bulk volume Vp is calculated (step 203), and the difference ΔV between the bulk volume and the solid in the solidification container 5 shown in FIG. The weight of the solid substance corresponding to the difference ΔV in the bulk volume is obtained as the target weight Wst based on the correlation between the weight of the bulk substance (gravel) and the bulk volume (step 204). Next, the transfer device 8 for the solid substance is driven to transfer the solid substance S to the measuring device 12 (step 205), and based on the weight signal from the measuring device 12, the weight of the solid substance transferred to the measuring device 11 is measured. Is determined to have reached the target weight Wst (step 20).
6). If the weight of the solid substance does not reach the target weight Wst, the drive of the transfer device 8 is continued, and if the weight of the solid substance reaches the target weight Wst, the drive of the transfer device 8 is stopped (step 207). Thereafter, the solid substance transferred to the measuring device 12 is automatically sent to the kneading tank 6.

The details of the processing functions of the control device 19 will be described with reference to the flowchart shown in FIG. The control device 19 first receives a processing signal from the control device 18, a solidified material weight signal from the measuring device 13, and a water weight signal from the measuring device 14 (step 300). Next, the target weights Wxt and Wyt of the solidified material (cement) X and the water Y based on the pellet weight and the target weight Wst of the solid substance when the surface dose rate reaches the reference value based on the processing signal from the controller 18. Is calculated (step 301). This can be calculated as follows. First, the mixing ratio of the solidifying material and water is determined in advance. This mixing ratio is determined by what is used for the solidifying material. For example, in a normal cement, a cement paste is prepared by mixing water / cement at a weight ratio of 4/5. Also,
Since this solidifying material paste also fills the gap between the waste pellets and the solid substance in the solidifying container 5,
What is obtained by subtracting the total volume of the waste pellets and the solid substance from the volume of the solidification container (200 liters) is the required volume of the solidification material paste. Here, the deposition of the pellet is obtained from the weight of the pellet and its specific gravity, and the deposition of the solid substance is obtained from the weight (target weight) of the solid substance and its specific gravity. When the required volume of the solidifying material paste is determined in this way, the relationship between the volume of the solidifying material paste and the weight of the solidifying material and water is evaluated in advance as data corresponding to the above-mentioned weight ratio, and this is evaluated by the control device. 19, target weights Wxt and Wyt of the solidifying material and water corresponding to the required volume of the solidifying material paste are obtained.

Thus, the target weight W of the solidified material and water
When xt and Wyt are obtained, the valves 9 and 10 are opened, and the solidified material X and water Y are respectively transferred to the measuring devices 13 and 14 (steps 302 and 305), and weighed based on the weight signals from the measuring devices 13 and 14. It is determined whether the solidified material and the water transferred to the vessels 13 and 14 have reached the target weights Wxt and Wyt, respectively (steps 303 and 306). If the solidified material and water do not reach the target weights Wxt and Wyt, respectively, the valves 9 and 10 are kept open, and if they reach the target weights Wxt and Wyt, the valves 9 and 10 are closed (steps 304 and 3).
07). Thereafter, the solidified material and the water transferred to the measuring devices 13 and 14 are automatically sent to the kneading tank 6.

Next, an operation example of the pellet solidification processing equipment of this embodiment will be described. First, the operator operates the input key 16a of the operation device 16 to input a target uniformity in advance. The target uniformity is 7 as described above.
Input 0% or more, for example, 90%. Along with this, the controller 17 obtains 90 from the correlation shown in FIG.
A target bulk volume of about 100 liters corresponding to a% uniformity is set. Next, the operator operates the selection key 16b of the operating device 16 to select a pellet desired to be solidified, for example, the pellet A, from the pellets A, B, and C. Accordingly, the control device 17 starts driving the transfer device 7a, and the pellets A are transferred from the storage container 1a to the measuring device 11.

When the pellet A selected by the measuring device 11 is transferred to the measuring device 11, the pellet A is measured by the measuring device 11 by the processing function of the control device 17 and transferred to the kneading tank 6, and the control is performed. The solid substance, that is, the gravel S, is measured by the measuring device 12 by the above-described processing function of the device 18 and transferred to the kneading tank 6, and the solidified material (cement) X and water Y are measured by the measuring device 13 by the processing function of the control device 19. , 1
4 and transferred to a kneading tank 6. For example, assuming that the weight of the pellet A when the dose rate reaches the reference value is 50 kg, when the pellet A of 50 kg is transferred to the measuring device 11, the transfer of the pellet A to the measuring device 11 is stopped, and the measuring device 11 The pellets A of 50 kg are transferred to the kneading tank 6. Assuming that the target bulk volume is 100 liters as described above, the controller 18 determines 40 liters as the bulk volume of the pellet A from the correlation corresponding to the pellet A shown in FIG. From the correlation, a target weight of 100 kg of the solid substance S corresponding to 60 liters, which is the difference between the target bulk volume of 100 liters and the bulk volume of the pellet A of 40 liters, is obtained. It is transferred to the kneading tank 6. Further, the control device 19 obtains the target weights Wxt and Wyt of the solidified material (cement) X and the water Y based on the weight of the pellet A of 50 kg and the weight of the solid substance S of 100 kg.
The weights of the solidified material and water are measured in 3 and 14 and transferred to the kneading tank 6.

The pellets A, the solid substances S, the solidified material X and the water Y thus transferred to the kneading tank 6 are mixed and stirred in the kneading tank 6 by a rotary stirring blade 6b connected to a driving device 6a. 20 is opened and injected into the solidification container 5 and transferred. As shown in FIG. 8, the solidified material injected into the solidification container 5 and solidified was a sound solidified material in which the pellets A and the solid substances S were uniformly dispersed in the solidified material X.

[0066] According to this embodiment, as described above, it is possible to solidify the different waste pellets in a state uniformly dispersed using the same equipment.

A second embodiment of the present invention will be described with reference to FIGS. In this embodiment, the present invention is applied to a solidification treatment facility of an injection solidification system. In the figure, the same reference numerals are given to members equivalent to the members shown in FIG.

In FIG. 9, the solidification treatment equipment of this embodiment has another kneading tank 30 separately from the kneading tank 6, in which the pellets from the pellet storage containers 1a, 1b, 1c are mixed with the solid. The solid matter from the solid matter storage container 2 is transferred, and the solidified material and the added water from the solidified material storage container 3 and the water storage container 4 are transferred to the kneading tank 30, and are separately mixed and stirred. Like the kneading tank 6, the kneading tank 30 includes a rotary stirring blade 30b connected to a driving device 30a, and a discharge pipe is provided with a valve 31 for opening and closing the pipe.

The processing functions of the control devices 17, 18 and 19 are substantially the same as those of the first embodiment. However, the control device 18 stores the correlation shown in FIG. 10 instead of the correlation shown in FIG. 4 as the correlation between the uniformity of the dispersion of the pellets in the solidification container 5 and the bulk volume, since the present embodiment uses the injection solidification method. Have been.

Here, FIG. 10 shows the correlation between the uniformity of the pellet dispersion and the bulk volume in the case of the injection solidification method, and the solidification container 5 also has a capacity of 200 liters. As described above, in the injection solidification method, the uniformity of pellet dispersion and the bulk volume are in a linear proportional relationship.
In addition, the bulk volume corresponding to 70% homogeneity in consideration of a sufficient safety factor usually corresponds to about 70% of the volume of the solidification container, which is 14% of the solidification container 5 of 200 liters.
0 liters worth.

An example of the operation of the equipment for solidifying pellets according to this embodiment will be described. As in the first embodiment, first, the operating device 16
By operating the input key 16a, the target uniformity is input in advance. The target uniformity is again 70
% Or more, for example, 90%. Accordingly, a target bulk volume of about 180 liters corresponding to 90% uniformity is set in the control device 17 from the correlation shown in FIG.
Next, when the selection key 16b of the operation device 16 is operated to select a pellet desired to be solidified, for example, the pellet A, from the pellets A, B, and C, the control device 17 starts driving the transfer device 7a, and the storage container 1a The pellets A are transferred to the measuring device 11. The weighing device 11 measures the weight of the transferred pellets A, and when the weight reaches the reference value, the control device 17 stops driving the transfer device 7a, and the weighing device 11 outputs the weighed pellets A from the measuring device 11. Kneading tank 6
Is transferred to The weight at this time is, for example, 50 kg.
Then, the controller 18 determines the bulk volume of 40 liters of the pellet A corresponding to the weight of 50 kg from the correlation corresponding to the pellet A shown in FIG. 5, and obtains the target bulk volume of 180 liters from the correlation of the solid substance shown in FIG. A target weight of 250 kg of the solid substance S corresponding to 140 liter which is a difference from the bulk volume of the pellet A of 40 liter is obtained, and 250 kg of the solid substance is measured by the measuring device 12 and transferred to the kneading tank 6.

The pellets A and the solid substances S transferred to the kneading tank 6 in this manner are fed into the kneading tank 6 by the driving device 6.
The mixture is mixed and stirred by the rotary stirring blade 6b connected to a, and is put into the solidification container 5 with the valve 20 opened. The solidification container 5 into which the mixture of the pellets A and the solid substances S has been charged is mixed in the kneading tank 3
It is transported below 0 .

On the other hand, the data of the weight of the pellet A and the target weight of the solid substance S are sent from the controller 18 to the controller 19, and the controller 18 reduces the weight of the pellet A to 50Kg and the target weight of the solid substance S to 250Kg. Target weights Wxt and Wyt of the solidified material (cement) X and water Y are determined based on the weights, and the weights of the solidified material and water are measured by the measuring devices 13 and 14 and transferred to the kneading tank 30. The solidified material X and the water Y transferred to the kneading tank 30 are supplied to the driving device 30a in the kneading tank 30.
The solidified material paste is produced by mixing and stirring with the rotary stirring blade 30b connected to the solidified material, and the solidified material paste is injected into the solidification container 5 by opening the valve 31. The solidified material in which the solidifying material paste was injected into the solidifying container 5 and solidified was a sound solidified material in which the pellets A and the solid substances S were uniformly dispersed in the solidifying material X as shown in FIG.

[0074] Also according to this example as described above, it is possible to solidify the different waste pellets in a state uniformly dispersed using the same equipment.

[0075]

According to the present invention, it is possible to solidify the different waste pellets in a state uniformly dispersed using the same equipment.

[Brief description of the drawings]

FIG. 1 is a diagram showing a facility for solidifying radioactive waste pellets according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing processing functions of a control device of the pellet transfer device.

FIG. 3 is a flowchart showing processing functions of a control device of the solid substance transfer device.

FIG. 4 is a diagram showing a correlation between target uniformity and bulk volume in kneading and solidification.

FIG. 5 is a diagram showing a correlation between weight and bulk volume of three types of pellets in a solidification container.

FIG. 6 is a diagram showing a correlation between weight and bulk volume of a solid substance (gravel) in a solidification container.

FIG. 7 is a flowchart showing processing functions of a control device of the solidified material transfer device and the water transfer device.

8 is a view showing a state of a solidified body solidified by the equipment shown in FIG.

FIG. 9 is a view showing a solidification treatment facility for radioactive waste pellets according to a second embodiment of the present invention.

FIG. 10 is a diagram showing a correlation between target uniformity and bulk volume in injection solidification.

11 is a view showing a state of a solidified body solidified by the equipment shown in FIG. 9;

[Explanation of symbols]

 1a to 1c Pellet storage container 2 Solid substance storage container 3 Solidified material storage container 4 Additive water storage container 5 Solidification container 6 Kneading tank 7a to 7c, 8 Transfer device 9,10 Valve 11 to 14 Meter 15 Radiation detector 16 Operation Device 16a Input key for target uniformity 16b Pellet selection key 17-19 Controller 30 Kneading tank

Continued on the front page (72) Inventor Yoshimasa Kiuchi 3-2-2, Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi Engineering Services Co., Ltd. (72) Inventor Masato Matsuda 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Energy Research Laboratory (72) Inventor Hidehisa Shiohara 1-3-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Tokyo Electric Power Company (72) Inventor Mamoru Tanaka 1-1-3, Uchisaiwaicho, Chiyoda-ku, Tokyo TEPCO Incorporated (58) Fields surveyed (Int.Cl. ⁷ , DB name) G21F 9/36 G21F 9/30

Claims (10)

(57) [Claims] A radioactive waste is dried and powdered, and a pellet obtained by compression-molding the radioactive waste is solidified in a solidification container using a solidifying material. A pellet storage container, a solid substance storage container in which a solid substance having a size similar to that of the pellet is stored, and a pellet and a solid substance are transferred from the pellet storage container and the solid substance storage container, A first kneading tank that mixes and stirs the mixture and puts the mixture into the solidification container; a pellet transfer unit that measures each of the pellets from the plurality of pellet storage containers and transfers the pellet to the first kneading tank; Solid substance transfer means for measuring a solid substance from a substance storage container and transferring it to the first kneading tank; and one kind of pellet from the different kinds of pellets A first transfer control means for controlling the pellet transfer means so that the selected predetermined weight of the pellets is transferred to the first kneading tank; and a pellet selected by the first transfer control means. A target weight of the solid substance necessary for uniformly dispersing and solidifying in the solidification container is determined, and the solid substance transfer is performed so that the target weight of the solid substance is transferred to the first kneading tank. e Bei a second transfer control means for controlling the means, the second feed control section, the different types of pellets
Pellet weight and pellet volume for each
The weight of the solid substance required for uniform dispersion and solidification in the vessel
Is stored, and based on the correlation, the first
Solid corresponding to a given weight of pellets transferred to the kneading tank
Solidification facility radioactive waste pellets, wherein Rukoto determined body-like material weight as the target weight of the solid material. 2. The facility for solidifying radioactive waste pellets according to claim 1, further comprising a first operating means for inputting a numerical value of a target uniformity of the dispersion of the pellets in the solidification container, wherein the second transfer is performed. The control means calculates a target weight of the solid substance so as to obtain the target uniformity. The solidification treatment facility for radioactive waste pellets, wherein: 3. The facility for solidifying radioactive waste pellets according to claim 1, further comprising second operating means for instructing selection of any one of the different types of pellets, wherein said first transfer control means comprises: A solidification facility for radioactive waste pellets, wherein the type of pellets transferred to the first kneading tank is selected according to a selection signal from the second operating means. 4. The solidification treatment facility for radioactive waste pellets according to claim 1, wherein the solidified material storage container and the water storage container for storing the solidified material and the added water, respectively, and the solidified material storage container and the water storage container The solidifying material and the added water are transferred, and they are mixed by stirring and transferred to the solidifying container.
A kneading tank, solidifying material and water transfer means for measuring the solidifying material and water from the solidifying material storage container and the water storage container, respectively, and transferring the solidified material and water to the second kneading tank, and transferred to the first kneading tank. A third transfer for controlling the solidifying material and water transfer means such that a solidifying material and water having a weight corresponding to a predetermined weight of the pellets and a target weight of the solid substance are transferred to the second kneading tank; A solidification treatment facility for radioactive waste pellets, further comprising control means. 5. The facility for solidifying radioactive waste pellets according to claim 4, wherein said second transfer control means comprises:
For each of the different types of pellets,
Of the pellet weight and bulk volume in the solidification vessel
Correlation and weight and bulk volume of solid material in the solidification vessel
And a second correlation with the selected pellet
The first correlation, the second correlation, and transfer to the first kneading tank
The specified weight of the pellets to be
From the target bulk volume required for uniform dispersion and solidification,
The solidification treatment facility for radioactive waste pellets , wherein a target weight of the body material is determined, and the target bulk volume is 70% or more of the volume of the solidification container. 6. The radioactive waste pellet solidification equipment according to claim 1, wherein said first transfer control means measures a surface dose rate of the pellets transferred to said first kneading tank. And a means for stopping the transfer of the pellets to the first kneading tank when the surface dose rate obtained by the dose rate detection means reaches a reference value. Facility. 7. The solidification facility for radioactive waste pellets according to claim 1, wherein the pellet transfer means and the solid matter transfer means respectively transfer the pellets and the solid matter transferred to the first kneading tank. A solidification facility for radioactive waste pellets, characterized by having a measuring device for receiving and measuring the weight in the middle. 8. A method for solidifying radioactive waste into a powder, drying and pulverizing the radioactive waste into a solidified material, and solidifying the pellet in a solidification container using a solidifying material. Prepare solid material in advance, select one type of pellet from different types of pellets,
Transferring a predetermined weight of the selected pellets to a kneading tank; presetting each of the different types of pellets
The pellet weight and pellets were evenly distributed in the solidification vessel.
From the correlation with the weight of the solid substance required for solidification,
Corresponds to pellets of specified weight transferred to the first kneading tank
To obtain the target weight of the solid substance required to uniformly disperse and solidify the selected pellets in the solidification container, and to obtain the target substance weight of the solid substance in the kneading tank. Wherein the pellets and the solid substance are mixed and stirred in the kneading tank and charged into the solidification container. 9. The method for solidifying radioactive waste pellets according to claim 8, wherein the solidifying material and added water are transferred to the kneading tank together with the pellets and the solid substance, and are mixed, stirred and poured into the solidification vessel. A method for solidifying radioactive waste pellets. 10. The method for solidifying radioactive waste pellets according to claim 1, wherein the weight and surface dose rate of the pellets transferred to the kneading tank are measured, and when the surface dose rate reaches a reference value, the kneading tank is measured. A method for solidifying radioactive waste pellets, comprising stopping the transfer of the pellets to the wastewater.