A device for cementing impregnation of fine radioactive and toxic waste

 

(57) Abstract:

The device relates to the field of radioactive waste management (RW), in particular, a method of cementing, and is intended for monolithic impregnation of fine radioactive and toxic waste, having a bulk volume of voids. Effect: simplified hardware design of the cementation process, improving radiation safety during operation of the device, increase productivity, improve the quality of the final cement compound and the receiving end of a cement compound with a volume equal to the original bulk volume of radioactive waste. The invention consists in the supply of cement under pressure through a tube into a container pre-filled RAO, and subsequent impregnation RAO throughout the bulk volume by filling with cement mortar all voids and pores. The device comprises a sealed work box containing the box, equipped with rubber gloves, and a door driven by the actuator, a cart with a vibrating plate on which is mounted a container with radioactive waste, probe, mechanism for moving the probe, site preparation, cement, dosing pump, ventilation tive (RAO) and toxic waste in particular, a method of cementing, and is intended for monolithic fine radioactive and toxic waste unburnable and napisuemye fragments of building structures and dismantled installations, the bottom ash from incineration of radioactive waste, spent granular sorbents, ion-exchange resins, etc.,), with subsequent disposal of the final cement compound in containers storage surface type. Most effectively the inventive device can be realized by cementing ash residue resulting from the combustion of RAO and which polydisperse powder dusting material with large inorganic (glass, ceramics, metal) inclusions. The device can also be used in a joint cementing liquid and solid radioactive waste. The device is designed for operation at nuclear power plants and radioactive waste.

A device for cementing RAO [1], including the capacity for dry cement, the capacity for raw and reagents barrel cargo for mixing and rotating device. Barrel placed in her cargo to fill mixing dry cement, solid RW and shuts the liquid phase, closed kr the organization of a mixture of a barrel together with the load for mixing and the resulting cement compound sent for disposal.

The disadvantages of the known devices are:

- significant increase in the volume of the final cement compound compared with the original volume RAO (1.5-2 times), leading to increased costs for construction and maintenance of repositories for radioactive waste. The increase is associated with the presence of mixing of cargo disposed together with the ultimate compound, and the need to improve the fluidity of cement mortar (increase in volume of the liquid phase of the solution, or reducing the degree of inclusion RAO) for the normal operation of the mixer when mixing raw with cement mortar;

- the formation of a large number of secondary liquid waste that require further processing, because of the presence of a metering and mixing equipment in contact with raw and require decontamination;

- low degree of inclusion RAO in the final cement compound (for example, when cementing ash filling rate is 20-30% by weight, cementing waste ion-exchange resin and granular sorbents - 10-20% by weight);

heightened danger and unreliability of the device because of the possibility of mechanical damage mixing g is enough pre-sorting of waste;

education lack of uniformity in the final cement compound characterized by the presence of voids that during prolonged storage leads to a decrease in the required technical characteristics (compressive strength, speed leaching), and, ultimately, to a relatively rapid destruction of the main barrier to release of radionuclides into the environment.

Closest to the present invention is a device for curing ash residue of organic radioactive waste [2], containing a sealed chamber communicating with her through the dosing capacity for bottom ash, cement and sealer, a container for curing and the power control device is located outside the chamber, characterized in that in a sealed chamber under the output dispensers bottom ash and cement is vibrotransporter, under the edge of which it is the container, vibrating table, gripping mechanism to move the container and the lid with pneumatic actuator for sealing the container in the housing which is equipped with fittings for connection of piping from tank sealer, systems compressed air and vacuum, and outside of the camera in the pipeline system sozdaniya. Solidification of radioactive waste in the container is a mixture of bottom ash with cement in dry form, transport them in a container on vibrotransporter and applying sealer wind blow in vakuumirovaniya container by changing the pressure in the container from vacuum up the excess.

The drawbacks are:

- complex instrumentation of the cementation process, associated in particular with the vacuum container and alternately repeated pressure change in the container from vacuum to excess;

the low productivity associated with the impossibility of 100% of the useful volume of the barrel, due to multiple repetitions of cementing in a single container by means of aerodynamic blow;

- the presence of radiation dangerous stages of the technological process (batching RAO, mixing dusty dry raw cement in dry form on vibrotransporter) and equipment in contact with RAO (dispensers, vibrotransporter);

- the formation of liquid (water decontamination) and hard (coarse and fine filters clean) secondary radioactive waste requiring further processing.

The technical problem is to sovershenstvanie apparatus registration device;

improving radiation safety during operation of the device;

- increase performance of the device;

- receiving at the device end of a cement compound with a volume equal to the original bulk volume RAO;

- improving the quality of the final cement compound.

For the technical solution is proposed a device for cementing RAO impregnation containing sealed a work box, a container for radioactive waste, the vibrating plate, the container-dispenser and the control unit of the device, located outside of Boxing, characterized in that the hermetic work box contains box, equipped with rubber gloves, and a door driven by the actuator, and tight work box is equipped with a ventilation system, which includes tranporter to determine the level of depression and made in the form of a branch pipe connected to the process ventilation, and decontamination system consisting of a nozzle decontamination, pipeline with the installed solenoid valve and discharge pipe located in the bottom part of the hermetic work of Boxing and designed to drain decontamination water, sealed razlozhenny in the upper part of the sealed working Boxing and is equipped with a level gauge cement; in addition, the vibrating plate for placing the container with RAO installed on the cart with the actuator and the container with RAO further comprises a cover; site preparation of the cement slurry contains the above-mentioned container-dispenser for water, fitted with a water level gauge and solenoid valves on the inlet and outlet capacity dosing pump for water and a water meter and mixer that contains the inlet water pipe for loading cement and the drain pipe with solenoid valve and the mixer is connected via a pipe to a drain pipe for draining the decontamination of water in a sealed working Boxing; in addition, the device comprises a supply system of cement in the container with radioactive waste, including the pump and with the installed electric contact pressure gauge.

The device is simplified by the use of a probe (single or continuous) and a dosing pump for feeding pressure of the cement slurry in the container with radioactive waste, which allows a fundamentally new way to carry out the cementing RAO impregnated directly into the container (for example, in the standard 100-200 litre barrels) without pre-sorting RAO and without mixing raw with cement RA the equipment and increases the degree of inclusion of RAO in the final cement compound without increasing its volume compared to the original bulk volume of radioactive waste.

The reduction in the product of the number of equipment in contact with radioactive waste, will not only simplify the device and reduce the capital cost of the equipment, but also to improve the process performance by reducing the stages of the technological process and operating time of the device and by reducing the amount of secondary liquid radioactive waste generated in large quantities it is decontamination of equipment and require further processing.

Impregnation RAO visokoprohodim cement mortar, carried out in the proposed device by means of a dosing pump and probe, allows, using the space between particles of radioactive waste in bulk volume, monolight RAO without mixing them with cement mortar in special mixers that results when the device is end-cement compound with a volume equal to the original bulk volume of waste, and thus to reduce the cost of construction and maintenance of radwaste repositories.

The pump makes it possible to transport the cement slurry through the pipeline under pressure not more than 1 MPa, controlled by electric contact pressure gauge, and to supply Zema, equal to the height of the container with radioactive waste, with an extension at the bottom and openings for free passage of cement. The disposable probe is used for cementing relatively large RAO (fragments dismantled installations, construction waste, ceramics, metal, etc), is installed in the container prior to the filling RAO and deposited together with the final cement compound.

The probe constant is introduced into the container already filled with fine RAO, and is a tube with a pointed tip, and holes at the bottom. After cementing RAO probe is removed and used repeatedly.

The holes in the bottom of the probe serve for the supply of cement in the bottom portion of the container with radioactive waste, which allows cement mortar with high efficiency to fill in the bulk volume of all the smallest voids and pores RAO, soaking the waste evenly in all directions from top to bottom of the container and ensuring the quality of the cement compound throughout the volume of radioactive waste.

Radiation safety during operation of the device is increased, mainly due to the exclusion of radiation dangerous stages of dispensing and peremeshivanija (dispensers, mixers, vibrotransporter).

In addition, radiation safety is increased due to the isolation container with radioactive waste from the work area to prevent contamination of work surfaces, equipment and working area air radionuclides, as most incoming cementing fine RAO are loose, dusty radiation hazardous material.

In the proposed device cementing is carried out in a sealed box with a vacuum of at least 20 mm of a water column. Management cementation process is carried out with the control unit a device located outside of Boxing. Contamination of the surfaces of the equipment in the box is controlled devices radiation safety. After cementing the box is deactivated by water and is collected in the bottom part of the working box. To drain the decontamination of water in the device is provided with a drain pipe with solenoid valve, which allows you to return decontamination water pipeline in the mixer for use in subsequent cementing. Return decontamination of water in the mixer is designed to operate without obrisati process.

The quality of the final cement compound increases not only due to the thorough impregnation of the raw cement mortar is fed through the probe, but also due to the inclusion in the device node of the preparation of the cement slurry, comprising a container-dispenser for water, water level gauge, solenoid valves on the input and output capacity of the pump, water meter and mixer. The site allows accurate metering of water and cement, to adjust the composition of the solution in a process that improves the quality vysokopronitsaemogo cement mortar. Thus prepared cement mortar capable of more completely and evenly fill the voids and pores of fine RAO, resulting in durable, resistant to aggressive environmental factors such as seasonal temperature changes, the leaching of radionuclides in ground water) finite cement compound with a high degree of filling by RAO.

In addition, the vibration of the container obtained by impregnation of a compound provided by the device, the vibrating plate can produce a homogeneous final cement compound that improves its quality (increases the compressive strength, reduces the leaching parameters of radionuclides).

The drawing shows a diagram of the inventive device for cementing impregnation fine and toxic radioactive waste. The device consists of a sealed working box with 1 window with rubber gloves 2 and a door equipped with an actuator 3, and the box is equipped with a ventilation pipe 4 and tranporation 5, and decontamination system, which includes the pipeline for decontamination of water 6 with the installed solenoid valve 7, the nozzle to decontaminate 8 and the drain pipe 9 for discharging the decontamination of water, equipped with an electromagnetic valve 10, the cart drive and installed on the vibrating plate 11 is placed on the container RAO 12, a transmitter 13, the mechanism for moving the probe 14 with the level of filling of the container with cement mortar 15, site preparation cement mortar consisting of a container-dispenser for water 16 water level gauge 17, water meter 18, the solenoid valves on the inlet and outlet capacity dosing pump 19 and 20, the mixer 21 with a pipe for water supply 22, a pipe for supply of cement 23 and a drain pipe 24, is equipped with an electromagnetic valve 25, pump 26, pipe 27 with the installed electric contact pressure gauge 28.

Ustroystvami 11, served in a work box 1 there is fixed. The door 3 is closed, in your case 1, a vacuum of at least 20 mm of a water column controlled by the testimony of tranporter 5, then the container 12 is removed the cover. In the cement mixer 21 through pipe 22 is supplied with the necessary amounts of water (or liquid radioactive waste, or decontamination water), the amount of water is controlled by water meter 18 includes the mixer 21. In the mixer 21 through pipe 23 is loaded cement (or cement with additives that improve the quality of the solution and the final cement compound), preparing cement mortar. The probe 13 by means of the mechanism for moving the probe 14 is inserted into the container with RAO 12. Turns on the pump 26, the finished cement slurry through the drain pipe 25 is supplied under pressure not more than 1 MPa from the mixer 21 through the pipe 27 through the holes of the probe 13 in the bottom portion of the container with RAO 12. During impregnation controlled by the following parameters: pressure in the intake pipe 27 to the electric contact pressure gauge 28; consumption of cement on the performance of the pump 26; filling the container at the level of the cement slurry 15, mounted on the mechanism of AC is working from the container 12 formed with a cement compound. The container 12 is closed by a cover and vibiraetsya on the vibrating plate 11. The door opens to 3 business case 1, the container 12 with a cement compound is transported to the storage of radioactive waste. Ventilation of the working box is disabled. On completion of the works site preparation and feeding system, cement mortar, including the mixer 21, the pump 26 and line 27, washed. Wash solution is discharged into the mixer 21 and used in the next cycle cementing. Work box 1 on completion of the works is deactivated in the following way. On the pipeline decontamination 6 opens the electromagnetic valve 7. Through the jet decontamination 8 in the working case 1 water for washing all surfaces of the box. Decontamination water after washing is collected in the bottom part of the desktop case 1. Through the drain pipe 9, provided with a solenoid valve 10, decontamination water through pipes to the mixer 21 for use in the following cycles cementing. Thus, during operation of the device is formed of secondary radioactive waste.

In the Radon radon conducted research work and pilot testing of the device using various is trojstva. The results are shown in the table.

Cementing RAO impregnation on the proposed setup allows you to exclude from the process used in known devices, equipment for sorting, grinding and dosing RAO, which greatly simplifies the process. The process also strips out the equipment for mixing raw with cement mortar, which eliminates damage to the mixers large fragments RAO and avoid formation of secondary waste generated during decontamination mixers and dispensers. Reducing the number of equipment and, accordingly, the duration of operation of the device, as well as lack of education secondary radioactive waste requiring additional processing, can improve the performance of the claimed device by 20-30% in comparison with the known devices.

By reducing the number of operations and equipment that come in contact with radioactive waste, as well as by conducting cementing working in an airtight box, isolated from the work area, increases radiation safety during the process of cementing.

The proposed device poses the result to obtain the final cement compound by volume, equal to the original bulk volume of radioactive waste, as well as the improvement of technical characteristics of the resulting cement compound, namely increases the degree of inclusion of radioactive waste in cement compound (for example, ash residue from the combustion of RAO to 50-65% by weight, while during operation of the known devices up to 30-40% by weight), increases the strength of the final cement compound and reduces leaching of radionuclides due to receipt of a dense homogeneous compound without voids (see table).

The proposed device allows you to improve the performance of the cementation process, to improve radiation safety during technological process, to simplify the process and get the final cement compound with improved properties and a volume not exceeding the original bulk volume americium RAO. This device can be manufactured using standard equipment for the conditioning of radioactive waste at nuclear power plants and radioactive waste.

LITERATURE

1. Nikiforov, A. S., Kulichenko centuries, Zhikharev M. I. Disposal of liquid radioactive waste. - M.: Energoatomizdat, 1985, S. 132-133.

2. Syromyatnikov Century the practical radioactive waste and device for its implementation. Patent SU 1435057 A1, MKI5G 21 F 9/16, Appl. 4167053/25 from 22.12.86, publ. 30.10.93, bull. 39-40.

A device for cementing impregnation of fine radioactive and toxic waste containing sealed a work box, a container for radioactive waste, the vibrating plate, the container-dispenser and the control unit of the device, located outside of Boxing, characterized in that the hermetic work box contains box, equipped with rubber gloves, and a door driven by the actuator, and tight work box is equipped with a ventilation system, which includes tranporter to determine the level of depression and made in the form of a branch pipe connected to the process ventilation, and decontamination system consisting of a nozzle decontamination, pipeline with the installed solenoid valve and drain pipe located in the bottom part of the hermetic work of Boxing, designed to drain decontamination water, also sealed a work box includes a probe with holes made in the lower part of the probe, and the mechanism for moving the probe, located in the upper part of the sealed working Boxing and is equipped with a level gauge cement; except for the rich container with radioactive waste further comprises a cover; site preparation of the cement slurry contains the above-mentioned container-dispenser for water, fitted with a water level gauge and solenoid valves on the inlet and outlet capacity dosing pump for water and a water meter and mixer that contains the inlet water pipe for loading cement and the drain pipe with solenoid valve and the mixer is connected via a pipe to a drain pipe for draining the decontamination of water in a sealed working Boxing; in addition, the device comprises a supply system of cement in the container with radioactive waste, including the pump and the pipeline with the installed electric contact pressure gauge.

 

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