RU2301468C1 - Device for case-hardening finely dispersed radioactive and toxic wastes by impregnation - Google Patents

Abstract

FIELD: recovering radioactive wastes.

SUBSTANCE: proposed device for case-hardening finely dispersed radioactive and toxic wastes by impregnation has sealed working box, radioactive waste container with cover, and vibratory plate for disposing radioactive waste container mounted on power-driven truck. In addition, it has liquid dosing tank provided with level gage and electromagnetic valves at its inlet and outlet, as well as mixer incorporating liquid-carrying pipe, cement-charging pipe, and drain pipe with valve. It also has system for feeding cement mortar to radioactive waste container incorporating dosing pump and pipeline with electric-contact pressure gage, device operation control unit disposed beyond box, and sealed working box. In addition, device has window equipped with rubber gloves and power-driven door, as well as ventilation system and decontamination system incorporating decontaminant spray nozzle, pipeline with valve and drain pipe disposed in bottom part of sealed working box.

EFFECT: enhanced radiation safety, improved labor conditions.

1 cl, 2 dwg

Description

The invention relates to the field of radioactive (RW) and toxic waste reprocessing by cementing and is intended for the monolithization of finely dispersed radioactive and toxic waste (non-combustible and non-compressible fragments of building structures and dismantled plants, ash residue from the burning of radioactive waste, etc.) with subsequent long-term storage or burial of the final cement compound in solid radioactive waste storage facilities. The device can also be used for joint cementing of liquid and solid radioactive waste. The device is intended for operation at nuclear power plants and radioactive waste disposal facilities.

A device for solidification of waste (Method for solidification of waste, and apparatus, waste form, and solidifying material therefore. US patent No. 5463171, G21F 9/00, application. No. 123359 from 09.17.93, publ. 31.10.95), in in particular mixed SRW generated at nuclear power plants, including ash residue, including containers for cementitious material, water, reagents, weight batchers, a mixer, a curing container, a stirrer for mixing in a container.

The disadvantages of the known device are:

- low degree of inclusion of radioactive waste in the final cement compound (for example, when cementing ash, the degree of filling is 30-40% by weight), since the filling volume of the container with radioactive waste is 50%;

- reduced reliability of the device due to the possibility of mechanical damage to the stirrer for mixing in the container with large inclusions present in solid radioactive waste due to insufficient preliminary sorting of waste.

Another device for processing solid radioactive and toxic waste is known (Baulin A.M., Razuvaev N.A., Kovalenko Yu.A. Device for processing solid radioactive and toxic waste. Patent RU No. 2124771 C1, G21F 9/36, 9 / 28, application No. 97116250/25 of 09.24.97, published on 01/10/99, bull. No. 1), intended for converting radioactive or toxic ash into a cement-like state, consisting of a sealed chamber, a prechamber, a loading and unloading manipulator, a rotary table , cylindrical container, decontamination brush, sealing and pressure lid telescopic loading device, vibrobloka, ash container, and a mixing cement, compressor and vacuum pump.

The disadvantages of the device are:

- complex hardware design of the cementing process associated with operations with the container with radioactive waste, the availability of equipment for multiple changes in pressure in the container from vacuum to excess;

- reduced productivity associated with repeated repetitions of cementing cycles in one container;

- reduced reliability of the device, associated with the possibility of clogging with components of the cement mortar of the nozzles for supplying the sealant, compressed air, vacuum, telescopic loading device due to splashing when loading these components into the container;

- reduced reliability of the moving parts of the device, for example a telescopic loading device, due to the possibility of ash between the moving parts of the dust ash and cement and the high abrasiveness of this dust.

Closest to the proposed device is (Varlakov A.P., Gorbunova O.A., Nevrov Yu.V., Lifanov F.A., Barinov A.S. Device for cementing by impregnation of fine radioactive and toxic wastes. Patent RU No. 2199164 C2, G21F 9/28, application No. 200111423/06 dated 04/18/2001, publ. 02/20/2003, bull. No. 5), relating to the field of processing of radioactive (RW) and toxic waste, in particular, by cementing, designed for homologation of finely dispersed radioactive and toxic wastes (non-combustible and non-compressible fragments of building structures s and dismantled plants, bottom ash from waste incineration, waste granulated sorbents, ion exchange resins, and the like), followed by a final disposal cement compound in the storage vessel of the surface type and comprising a work sealed box; container for radioactive waste; vibration pad; capacity dispenser; the control unit of the operation of the device located outside the box; sealed working box contains a window equipped with rubber gloves, and a door driven by a drive; moreover, the sealed working box is equipped with a ventilation system, which includes a drag gauge for determining the vacuum level and is made in the form of a pipe connected to the process ventilation, and a decontamination system, consisting of a decontamination nozzle, a pipeline with an electromagnetic valve mounted on it and a drain pipe located in the bottom of a sealed working box designed to drain decontamination water; the sealed working box also contains a probe with holes made in the lower part of the probe, and a probe moving mechanism located in the upper part of the sealed working box and equipped with a cement mortar level gauge; in addition, a vibratory platform for accommodating a container with radioactive waste is mounted on a trolley with a drive, and the container with radioactive waste contains a cover; the cement preparation unit contains the aforementioned water metering tank equipped with a water level meter and solenoid valves at the inlet and outlet of the water metering tank, as well as a water meter and mixer, including a water pipe, a cement loading pipe and an electromagnetic drain pipe a valve, the mixer being connected via a pipeline to a drain pipe for draining decontamination water in an airtight working box; in addition, the device comprises a system for supplying cement mortar to a container with radioactive waste, including a metering pump and a pipeline with an electric contact pressure gauge installed on it.

The disadvantages of the known device are:

- loading cement into the mixer is done manually;

- the formation of a large amount of cement dust during manual loading of cement into the mixer due to opening and shaking bags of cement, which is not trapped and enters the room;

- uneven impregnation of the ash residue with cement mortar due to the possible passage of cement mortar along the wall of the container with radioactive waste and the probe tube as the path of least resistance;

- the presence of a piercing probe that requires cleaning from radioactive cement mortar when removing it from a container with radioactive waste;

- the use of a probe with a drive does not allow you to quickly remove the probe from the container with radioactive waste and close the container with a lid to prevent the radionuclides from escaping the airtight working box in case of emergency situations, such as a power outage, shutdown of process ventilation, breakdown of the probe drive.

The proposed device solves the technical problem of:

- improving the uniformity of RW impregnation in the container for RW and the quality of the final product;

- increase radiation safety during operation of the device;

- improving working conditions.

To solve the technical problem, a device is proposed for cementing by impregnation of fine radioactive and toxic waste, containing a sealed working box equipped with a window with rubber gloves, a door driven by a drive; a ventilation system including a weight gauge for determining the vacuum level, made in the form of a pipe connected to technological ventilation; a radionuclide filter, connected by a pipeline to a sealed working box and technological ventilation and containing a differential pressure sensor installed at the inlet and outlet of the radionuclide filter; decontamination system, consisting of a decontamination nozzle, a pipeline with a valve installed on it and a drain pipe with a valve located in the bottom of the sealed working box, designed to drain decontamination water; Also inside the sealed working box there is a mechanism for fixing the lid of the container for radioactive waste; a docking unit tightly connecting the cement mortar supply pipe to the pipe of the radioactive waste container installed on the cement mortar supply pipe from the mixer to the radioactive waste container; a cart with a drive, a vibrating platform for accommodating a container for radioactive waste is installed on the cart, in addition, the device includes a container for radioactive waste with a lid, which has a neck and a metal pipe extending along the central axis to the bottom of the container, while the inner diameter of the pipe is equal to or more than the diameter of the cement mortar supply pipe, and holes are made in the lower part of the pipe with a total area equal to or greater than the pipe opening area, also on the pipe at heights of 0.4-0.5 and 0.65-0 7 container heights, two rings with a diameter equal to 0.16-0.18 container diameters are located, in the lower part of the pipe at a height equal to 0.06-0.07 the container heights, a disk perforated over the entire surface is located, the outer diameter of which is the inner diameter of the container for radioactive waste, and on the disk there is a grid with a mesh size of 1 × 1 mm to 2 × 2 mm, while in the upper inner part of the container for radioactive waste at a height equal to 0.7-0.8 height of the container for radioactive waste, an outer diameter ring is made, equal to the inner diameter of the container for radioactive waste, and a width of 0.08-0.12 diameter of the container for radioactive waste; the device also includes a liquid dispensing tank equipped with a level gauge, upper and lower level sensors and electromagnetic valves at the inlet and outlet of the liquid dispensing tank; a cement hopper mounted on load cells; a transport container for cement, a mixer connected by a pipeline to a liquid dispensing tank, a metering pump and a cement hopper; a valve is installed on the drain pipe of the mixer; a screw conveyor connected to a mixer and a cement hopper, a fan, a cement dust filter, connected by a pipeline to a cement hopper and a fan and containing a differential pressure sensor installed at the inlet and outlet of a cement dust filter, a cement mortar supply system to a radioactive waste container, including a metering pump and a pipeline with an electric contact pressure gauge installed on it; the control unit of the operation of the device located outside the box.

Distinctive features of the proposed device is that it contains a hopper for cement mounted on load cells; transport container for cement; a screw conveyor connected to a mixer and a cement hopper; a mechanism for fixing the lid of the container for radioactive waste, placed in an airtight working box; cement dust filter; radionuclide filter; fan; in addition, the cement dust filter is connected by a pipe to the cement hopper and the fan, and also contains a differential pressure sensor installed at the inlet and outlet of the cement dust filter; the radionuclide filter is connected by a pipeline to a sealed working box and technological ventilation and contains a differential pressure sensor installed at the inlet and outlet of the radionuclide filter; in addition, the container for radioactive waste contains a neck and a metal pipe extending along the central axis to the bottom of the container, while the inner diameter of the pipe is equal to or greater than the diameter of the cement mortar supply pipe, and holes are made in the lower part of the pipe with a total area equal to or greater than the area the hole of the pipe, also on the pipe at a height equal to 0.4-0.5 and 0.65-0.7 of the height of the container, there are two rings with a diameter equal to 0.16-0.18 of the diameter of the container, at the bottom of the pipe at a height equal to 0.06-0.07 height of the container There is a perforated disk over the entire surface, the outer diameter of which is equal to the inner diameter of the container for radioactive waste, and on the disk there is a grid with a mesh size of 1 × 1 mm to 2 × 2 mm, while in the upper inner part of the container for radioactive waste a height equal to 0.7-0.8 of the height of the container for radioactive waste, a ring is made with an outer diameter equal to the inner diameter of the container for radioactive waste, and a width of 0.08-0.12 diameter of the container for radioactive waste; a docking unit tightly connecting the cement mortar supply pipe to the pipe of the radioactive waste container installed inside the sealed working box on the cement mortar supply pipe from the mixer to the radioactive waste container; in addition, the liquid dispensing tank is equipped with upper and lower liquid level sensors, and the aforementioned mixer is connected by a pipeline to the cement hopper.

The implementation of the container for radioactive waste with a lid can improve the uniformity of impregnation of radioactive waste and the quality of the final product. Cement mortar is pumped through the pipe and through the openings in the lower part of the pipe to the bottom of the radioactive waste container, then through perforation of the disk, cement mortar from the bottom of the radioactive waste container is fed into the bottom layer of radioactive waste, filling all voids and pores, the cement slurry rises from below up, impregnating radioactive waste. The diameter of the pipe of the container for radioactive waste should be equal to or greater than the diameter of the cement mortar supply pipe, so as not to create additional hydraulic resistance and not to increase the pressure in the cement mortar supply pipe. For the same reason, the total area of the holes in the lower part of the pipe should be equal to or greater than the area of the pipe opening. The disk perforated over the entire surface is designed for uniform supply of cement mortar to the RAW layer. A mesh with a mesh size of 1 × 1 mm to 2 × 2 mm on a perforated disk prevents RAW from spilling under the disk and clogging perforations; if the mesh size is smaller, this will prevent the penetration of cement into the RAW layer; if the mesh size is larger than the specified one, then this will result in clogging of the perforations of the disc. Two rings with a diameter equal to 0.16-0.18 of the diameter of the container, placed on the pipe at a height equal to 0.4-0.5 and 0.65-0.7 of the height of the container for radioactive waste, prevent the passage of cement mortar along the pipe as along the path of least resistance, if the diameter of the rings is smaller, then sections not saturated with cement mortar may remain in the inner layer of the radioactive waste, if the diameter of the rings is larger, then zones of the radioactive waste not saturated with cement can form behind the rings. The selected height of the rings allows you to evenly cement the radioactive waste with cement mortar, deviations from the selected height can lead to the formation of cementless zones of radioactive waste. A ring with a width of 0.08-0.12 diameter of the container for radioactive waste, made in the upper inner part of the container for radioactive waste at a height equal to 0.7-0.8 of the height of the container for radioactive waste, prevents the passage of cement along the wall in the upper part a container for radioactive waste, if the width of the ring is less than or greater than the specified, this can lead to the formation of uncemented RW zones.

The use of a docking station increases the radiation safety of the device. This type of connection allows in case of emergency situations, such as a power outage, ventilation systems, to quickly cover the radioactive waste container with a lid, thereby reducing the likelihood of radionuclides coming out of the sealed working box and contamination of the room and equipment with radionuclides.

The implementation of the transport container, cement hopper, screw conveyor fan and cement dust filter allows to improve working conditions by mechanizing the loading of cement into the cement hopper and mixer and capturing the cement dust generated when cement is loaded into the cement hopper and mixer.

Thus, the proposed device solves the problem.

Figure 1 presents a diagram of the inventive device for cementing by impregnation of fine radioactive and toxic waste.

Figure 2 presents the container for radioactive waste.

A device for cementing by impregnation of fine radioactive and toxic waste consists (see figure 1) of a sealed working box 1, equipped with a door 2 with a drive 3; a cover fixing mechanism (not shown in the diagram) and a docking unit 4; a ventilation system including a weight gauge 5, a radionuclide filter 6 with a differential pressure sensor 7; and a decontamination system, consisting of a decontamination nozzle (not shown on the diagram), a pipeline 8 with a valve 9 installed on it and a drain pipe with a valve 10 located on it; a radioactive waste container with a lid 11 located on a vibrating platform 12 mounted on a trolley 13 with a drive 14; a liquid dispensing tank 15 equipped with a level gauge 16, sensors of the upper 17 and lower 18 level and electromagnetic valves 19, 20 at the inlet and outlet of the liquid dispensing tank; mixer 21, valve 22; a metering pump 23 and a pipeline 24 with an electric contact pressure gauge 25 mounted on it; a hopper for cement 26 mounted on load cells 27; transport container 28; screw conveyor 29; cement dust filter 30 with a differential pressure sensor 31; fan 32.

The container for radioactive waste (11) consists (see figure 2) of the housing 33 with the ring 34 and the neck 35, closed by a cover 36; pipes 37 with holes 38 and rings 39; perforated disk 40, mesh 41.

The device operates as follows. Drive 3 starts, door 2 opens. The drive 14 is turned on and the trolley 13 is fed from the box 1. The container with RAO 11 is installed on the vibrating platform 12 of the trolley 13, the drive 14 is turned on and the trolley is fed into the working box 10. The drive 12 is turned on and the door 11 is closed, the exhaust ventilation is turned on and in working box 1 is created a vacuum of at least 200 Pa, controlled by the test of weight gauge 5, then the lid is removed from the container 11, the docking station 4 is fixed to the pipe 37 of the container for RW 11. The ultrafine cement from the warehouse enters the transport container 28, which sets using a lifting device at the cement receiving port of the cement hopper 26, the fan 32 is turned on to suck out the cement dust, the cement is poured into the cement hopper 26, the filling of the hopper 26 is monitored by load cells 27. The cement dust generated during loading is sucked into the cement dust filter 30, where is she lingering. At the end of the download, the fan 32 is turned off. The valve 19 is opened and the liquid dispensing tank 15 is filled with the required amount of liquid, the valve 19 is closed by a signal from the upper level sensor 17, the valve 20 is opened and the liquid is drained from the dispensing tank 15 to the mixer 21, the emptying of the dispensing tank 16 is controlled by the sensor signal the lower level 18. The mixer 21 is turned on, the screw conveyor 29 is turned on and the cement is loaded into the mixer 21, while the mass of cement is controlled according to indications from the load cells 27. The mixture is mixed for 2-5 minutes The cement slurry in the mixer 21, the valve 22 opens, the metering pump 23 is turned on, the finished cement mortar is supplied from the mixer 21 through the pipe 24, through the pipe 37 of the RAO container 11 to the bottom of this container, then through the holes of the perforated disk 40 (Fig. 2 ) the container for radioactive waste 11 is squeezed out into a layer of finely dispersed radioactive waste located in the container 11. During the impregnation, the following parameters are controlled: pressure in the discharge pipe 24 via an electrical contact pressure gauge 25; cement consumption by the productivity of the metering pump 23; filling the container for RW 11 visually. After filling the container with RAO 11 with cement mortar, the metering pump 23 is turned off, the docking device 4 is removed from the pipe 37, the container for RAO 11 is closed by a lid 36 (Fig. 2) using the lid fixing mechanism and subjected to vibration on the vibration platform 12. The working door 2 opens Box 1, the container for radioactive waste 11 with a cement compound is transported to the radioactive waste storage, door 2 closes. At the end of work, the mixer 21, valve 22, metering pump 23 and pipe 24 are flushed with clean water. The washing solution is discharged, sedimented, the clarified fraction is discharged into the sewer, the solid fraction is sent to a household waste dump. Work box 1 and the container for RAO 11 at the end of work, if necessary, are deactivated as follows. A valve 9 opens on the decontamination pipeline 8. Water is supplied to the working box 1 through the decontamination nozzle to flush all surfaces of the box and container 11. After the flush, decontamination water is collected in the bottom of the working box 1. Valve 10 opens, decontamination water is drained into a special sewer. The ventilation of the working box 1 is turned off.

The cementing of radioactive waste by impregnation on the proposed device allows you to:

- to improve the uniformity of impregnation of finely divided radioactive waste and the quality of the final product by 15-25% compared with the prototype;

- increase radiation safety by reducing the time for uncoupling the cement mortar pipeline with the pipe in the container for radioactive waste, which allows you to quickly close the container for radioactive waste with a lid when power is turned off and ventilation;

- improve working conditions due to the mechanization of cement loading into the cement hopper and mixer, as well as the capture of cement dust generated during cement loading.

This device can be manufactured using standard equipment for cementing fine waste at nuclear power plants and radioactive waste disposal sites.

The device is under development for the Smolensk NPP.

Claims (1)

A device for cementing by impregnation of fine radioactive and toxic waste, containing a sealed working box, a container for radioactive waste with a lid, a vibrating platform for placing a container for radioactive waste mounted on a cart with a drive, a liquid dispensing tank equipped with a level gauge and electromagnetic valves at the inlet and outlet a liquid dispensing tank, a mixer comprising a pipe for liquid, a pipe for loading cement and a drain pipe with a valve, in addition, the device It neighbors a cement mortar supply system into a container with radioactive waste, including a metering pump and a pipeline with an electric contact pressure gauge installed on it, a device operation control unit located outside the box, a sealed working box contains a window equipped with rubber gloves, and a door driven by a drive , a ventilation system including a weight gauge for determining the vacuum level, made in the form of a pipe connected to technological ventilation, and a decontamination system consisting of a decontamination nozzle, a pipe with a valve installed on it and a drain pipe located in the bottom of the sealed working box, designed to drain decontamination water, in addition, a valve is installed on the drain pipe, characterized in that it contains a cement hopper mounted on load cells, a transport container for cement, a screw conveyor connected to a mixer and a hopper for cement, a mechanism for fixing the lid of the container for radioactive waste, placed sealed working box, cement dust filter, radionuclide filter, fan, in addition, the cement dust filter is connected by a pipe to the cement hopper and the fan, and also contains a differential pressure sensor installed at the inlet and outlet of the cement dust filter, the radionuclide filter is connected by a pipeline with a sealed working box and technological ventilation and contains a differential pressure sensor installed at the inlet and outlet of the radionuclide filter, in addition, the container for radioactive waste contains throats well, and a metal pipe running along the central axis to the bottom of the container, while the inner diameter of the pipe is equal to or greater than the diameter of the cement mortar supply pipe, and holes are made in the lower part of the pipe with a total area equal to or greater than the pipe opening area, also on the pipe at a height equal to 0.4-0.5 and 0.65-0.7 of the height of the container, there are two rings with a diameter equal to 0.16-0.18 of the diameter of the container, in the lower part of the pipe at a height equal to 0.06-0, 07 container height, perforated disk is located on the entire surface, outer whose diameter is equal to the inner diameter of the container for radioactive waste, and on the disk there is a grid with a cell size of 1'1 to 2'1 mm, while in the upper inner part of the container for radioactive waste at a height of 0.7-0.8 height of the container for radioactive waste, a ring is made with an outer diameter equal to the inner diameter of the container for radioactive waste, and a width of 0.08-0.12 of the diameter of the container for radioactive waste, a docking unit that tightly connects the cement mortar supply pipe minutes for radioactive waste container installed inside the sealed box on the working slurry feed duct from the mixer to a container for radioactive waste, in addition to a liquid container provided with a metering sensors of the upper and lower liquid level, and the aforementioned mixer is connected to the conduit to the hopper for cement.

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