RU2825890C1 - System for tight conditioning of ash residue from incineration of radioactive wastes - Google Patents

Abstract

FIELD: processing of radioactive wastes.

SUBSTANCE: system for sealed conditioning of the ash residue from the incineration of radioactive wastes includes a sealed working box consisting of a housing containing an opening equipped with rubber gloves, a door, a unit for dosing and sealed loading of radioactive material, a container for radioactive wastes with a cover, a platform for placing a container for radioactive wastes, a system operation control unit, systems for cleaning from contaminants and radionuclides, a decontamination system, a mechanism for installing a cover of a container for radioactive wastes. Inspection windows are made in the housing, the door is made in the form of an opening with a slide gate, the container for radioactive wastes with a cover is made in the form of a barrel with a flexible package inside, platform for arrangement of container for radioactive wastes is made in the form of controlled roller table, mechanism for installation of cover of container for radioactive wastes is made in the form of pneumatic cylinder with electromagnet. Housing of the working box contains a unit for loading the ash residue from the bin, having a radioactivity level control sensor, having a screw conveyor connected to the loading chute for dosed supply of the ash residue.

EFFECT: invention simplifies the design.

5 cl, 5 dwg

Description

The invention relates to the field of radioactive waste processing, in particular, to systems for packaging ash residue from the incineration of radioactive waste, can be used for unloading, volume reduction, immobilization and sealing of ash residue from the incineration of solid radioactive waste (hereinafter referred to as SRW) for subsequent storage. The system is intended for use at nuclear power plants and radioactive waste disposal sites, has seismic resistance category II, climatic design type UHL, in atmospheric conditions of types I, II.

The prior art includes devices for unloading, preparing for storage and packaging SRW and their ash residue.

For example, a device for packing radioactive waste into barrels, "INSTALLATION FOR PACKING RADIOACTIVE WASTE MATERIAL IN DRUMS" (patent GB1594839A), is known. The device is a system consisting of a compression press operating in an alpha-partially impermeable compression box. The press contains at least two rods, to the upper ends of which a compression cylinder with a plunger acting downwards is attached, between the lower ends of which a compression table is attached, receiving a drum with waste. As a result of the operation of the device, simultaneously with the operation of compression of waste, a concrete shell is produced, closely associated with the waste.

The installation is compact and designed for operations to reduce the volume of radioactive waste by pressing and packaging it.

But the known device is not intended for unloading ash residue from the incineration of solid radioactive waste. Also, the design of the installation requires the consumption of a fairly large volume of additional, consumable material for binding radioactive waste with concrete, and waste pressed with concrete has a large mass and volume, which can create inconvenience during further transportation and require a large space for storage.

A device for filling packages with solid radioactive waste, compacting and packaging them is also known from the prior art (patent RU 2111567). The device comprises a packaging unit, a dispenser, connected with the possibility of multiple compaction of dosed portions of waste in packages by a press, a mechanism for loading and unloading packages, and a cyclone for sucking out dust-radioactive waste generated during their compaction, placed in a protective housing. The dispenser is made in the form of stationary installed and hermetically connected communicating boxes for loading, receiving, sorting and packaging waste, guillotine shears, and a feeder made in the form of a driven blade. The packaging box is equipped with a replaceable bag for combustible waste and a container for metal intended for remelting, located in its lower part. The loading and unloading mechanism is made in the form of a driven trolley. The waste sorted in the dispenser, the package is filled with a blade, compaction is done with a press stamp. Radioactive waste is poured and compacted in a bag in several stages. Radioactive dust is sucked out of the working area of the press.

The installation, in addition to cutting and sorting radioactive waste, including non-combustible radioactive waste, combustible radioactive waste, and non-ferrous metal scrap, is designed for compacting and packaging solid radioactive waste using a press ram.

The known device is not applicable for unloading ash residue from the incineration of solid waste because when it is loaded into the package, strong dusting of ash is possible. It is necessary to prevent dusting at the time of loading, i.e. in the loading unit with the dispenser, and not from the working area of the press, as in the known device. In addition, compaction in packages of dosed portions of waste in the known device requires multiple repetitions, which complicates the compaction process and increases the overall cycle time.

The closest to the proposed invention in its purpose and the technical result achieved is a device for cementing finely dispersed radioactive and toxic waste by impregnation, comprising a sealed working box, a container for radioactive waste with a lid, a vibration platform for placing the container for radioactive waste, mounted on a trolley with a drive. In addition, the device includes a liquid dosing tank equipped with a level gauge and electromagnetic valves at the inlet and outlet of the liquid dosing tank, and a mixer containing a liquid pipe, a pipe for loading cement and a drain pipe with a valve. The device also contains a system for feeding cement mortar into a container with radioactive waste; a control unit for the operation of the device, located outside the box, a sealed working box. The device also contains a window equipped with rubber gloves, and a door driven by a drive; a ventilation system, a radionuclide filter connected by a pipeline to a sealed working box and process ventilation, and a decontamination system consisting of a decontamination nozzle, a pipeline with a valve installed on it, and a drain pipe located in the bottom of the sealed working box (patent RU 2301468).

The known device allows loading finely dispersed residue, including ash, from the combustion of solid waste, effectively immobilizing the ash residue, preparing it for further transportation and storage. In this case, the ash residue is monolithized in the installation by means of cement compounding, which causes the complication of the device with additional units and the need to use a large volume of consumables, i.e. substances for performing the cementing operation. In addition, the device contains a complex cleaning and filtration system. Thus, the known device has the following disadvantages:

- complex design of the device;

- there is a need for additional expensive consumables and components for monolithic ash residue;

- the difficulty of controlling the hydrodynamic regime of impregnation of the ash residue with the cement compound, as well as its flow.

Thus, the technical problem is to improve the design of the device for packaging the ash residue from the combustion of solid radioactive waste in such a way as to ensure an increase in the tightness of the unit for loading and packaging radioactive material, while maintaining the production of immobilized ash residue and eliminating dusting, while eliminating the need to use consumables to obtain a more compact ash residue and reducing the complexity of the design of the device, improving the conditions of its use and maintenance.

The technical result consists in the fact that a system for packaging ash residue from the incineration of radioactive waste has been created, in which the design of the prototype device has been simplified by replacing the cementing unit with a unit for sealing and cutting off a flexible package with ash residue, a new unit for melting the ash residue has been introduced, the tightness of the units for loading and packaging the radioactive material has been increased, which has achieved the elimination of dusting and the minimization of the spread of radionuclides during the processes of loading and packaging the ash residue from the incineration of solid radioactive waste, while the effects of immobilization of the ash residue and elimination of dusting are preserved, the system has an additional function for additional melting of the ash residue before its packaging, i.e. The system makes it possible to perform loading and packaging operations in two ways depending on the initial levels of radioactivity of the loaded ash residue, eliminating the need to use consumables to obtain a more compact ash residue, providing improved conditions for the use and maintenance of the system, which in general has increased the efficiency, safety and ease of use of the system for packaging ash residue from the incineration of solid radioactive waste, as well as reducing the complexity of the design of the system.

The technical result is achieved in that the proposed system for hermetically sealed conditioning of ash residue from the incineration of radioactive waste includes a hermetically sealed working box consisting of a housing made in the form of a welded structure, contains an opening equipped with rubber gloves, a door driven by a drive, a unit for dosing and hermetically sealed loading of radioactive material, a container for radioactive waste with a lid, a platform for placing a container for radioactive waste, a control unit for the operation of the system located outside the box, a system for cleaning from contamination and radionuclides, a decontamination system located in the bottom part of the housing, a mechanism for installing the lid of the container for radioactive waste. Additionally, the housing has inspection windows, the door is made in the form of an opening with a slide valve, the container for radioactive waste with a lid is made in the form of a barrel with a flexible bag inside, the platform for placing the container for radioactive waste is made in the form of a controlled roller table, the mechanism for installing the lid of the container for radioactive waste is made in the form of a pneumatic cylinder with an electromagnet, in addition, the housing of the working box contains a unit for loading ash residue from a bin having a radioactivity level control sensor containing a screw conveyor located outside the working box, connected to the loading chute for metered feeding of ash residue, the specified flexible bag is hermetically connected to the chute with rings by means of a glove post to prevent dusting during loading, a sealing and cutting unit for the flexible bag made in the form of a pneumatic cylinder with a rod, with electrically heated clamping jaws located on it, one of which is equipped with a knife, drives with manipulators for the sealing unit and cutting the flexible a package, nozzles and pipelines for removing contaminants and radionuclides and for creating a vacuum, connected to a centralized special gas cleaning system located outside the working box, and an ash residue melting unit consisting of a muffle furnace with a crucible located away from the roller table, equipped with manipulators.

As an option, the body has at least two openings equipped with rubber gloves.

As an option, the work box body is equipped with at least two viewing windows.

As an option, the flexible package is made of polymer material.

The drives of the roller conveyor, the sealing unit and the flexible package cutting unit, and the container lid installation mechanism are remotely controlled.

In addition, the work box is equipped with control and measuring instruments located on the outside of the body.

The automated remote control system for the drives is located outside the work box.

The claimed system is illustrated by the following figures:

Fig. 1 shows a general view of the claimed system;

Fig. 2 shows a rear view of the claimed system;

Fig. 3 shows a top view of the claimed system;

Fig. 4 shows the mechanism for sealing and cutting a flexible package;

Fig. 5 shows the mechanism for installing the cover.

The claimed system comprises (Fig. 1) a metal housing 1, which is a welded structure in which openings 2 are made, equipped on the inside of the housing 1 with rubber gloves (not shown in the Fig.), by means of which repair work and part of the sealing process are carried out, inspection windows 3. On the end side of the housing 1 there is a door, which is an opening 4 with a damper valve, driven by a drive (not shown in the Fig.), and on the side of the housing 1 there is a mounting door 5 (Fig. 2).

On the upper part of the working box body there is a loading unit for ash residue from a bin having a radioactivity level control sensor containing a screw conveyor (not shown in the figure) located outside the working box, connected to the loading chute 6 for the metered supply of ash residue. The loading unit is equipped with manipulators 11 for performing technological operations, located on the front side part of the body 1.

Inside, along the body 1, near the opening 4 with the slide valve, a roller conveyor 8 is installed, controlled by a drive 9 (Fig. 1, 2). In addition, on the roller conveyor 8 there are emergency adjustable stops (not shown in the Fig.), preventing the barrel from shifting relative to the axis of the chute 6. On the roller conveyor there is a container for radioactive waste with a lid 21 (Fig. 5), made in the form of a barrel 7 (Fig. 1) with a flexible package inside (not shown in the Fig.). Closing and opening of the lid 21 is performed by a mechanism for installing the lid of the container for radioactive waste, consisting of a pneumatic cylinder 22 with an electromagnet 10 (Fig. 5), located in the upper part of the body 1. The said flexible package, in order to prevent dusting during loading, is hermetically connected to the chute 6 by rings (not shown in the Fig.) by means of openings 2 with rubber gloves.

Inside the housing 1, under the chute 6, there is a sealing unit and sections of a flexible package (Fig. 4), consisting of remotely controlled pneumatic cylinders 14, 15 with rods, with electrically heated pressure jaws 12, 13 located on them, jaw 12 is equipped with a knife.

In the projection of the rear part of the housing 1, away from the working area formed by the roller conveyor 8, the sealing and flexible package cutting unit, and the loading unit, there is an ash residue melting unit (Fig. 2, 3), consisting of a muffle furnace 16 with a crucible (not shown in the Fig.), equipped with manipulators 11 (Fig. 1).

To create a vacuum in the sealed housing 1 and to remove contaminants and radionuclides (Fig. 3), there is a nozzle 17 located at the top of the housing 1 in the area of the ash residue melting unit and connected to a centralized special gas cleaning system located outside the working box (not shown in the Fig.).

The decontamination system, including nozzles 19 for input and output of decontamination solutions, is located in the bottom part of the housing 1 (Fig. 2).

The drives of the mechanism for installing the lid 21 of the barrel 7, the sealing unit and the flexible package section, the roller conveyor 8, are made remotely controlled (not shown in the figure).

In addition, the working box is equipped with control and measuring devices - position sensors, which are located on the outer side of the housing (not shown in the Fig.). To monitor the processes occurring in the working area of the box, a video surveillance camera is provided (not shown in the Fig.), installed on the hatch of the technological opening 18 at the top of the housing 1 (Fig. 3). For lighting, lamps 20 are installed on the outer side of the housing (Fig. 1).

The automated remote control system for the drives is located outside the working box (not shown in the Fig.). The automated remote control system for the drives includes an automated operator workstation, sensors for monitoring process parameters and modes, controllers for input/output of signals from the sensors and generation of control signals transmitted to the drives. The control system includes devices for blocking (not shown in the Fig.) the actuation of mechanisms, drives in the event of a violation of the operating parameters of the sealed box or erroneous actions of the personnel, as well as tracking devices in the form of position sensors for moving elements (not shown in the Fig.) located inside the sealed box - barrel 7, its cover 21, crucible of the muffle furnace 16.

The hermetic conditioning system for ash residue from the incineration of radioactive waste operates as follows.

Before operation, the system must be assembled as follows. Install all attachments on body 1, including manipulators, drive 9. Install muffle furnace 16, drive roller table 8 inside body 1, connect it to drive 9, located outside body 1; install and adjust the sealing and cutting mechanism. Prepare barrel 7 by inserting a package and rings into it and install it on roller table 8. In the initial state before starting work, pneumatic cylinder 22 with electromagnet 10 of the barrel lid installation mechanism 7 must be in the upper position, and pneumatic cylinders of the package sealing and cutting mechanism must be in a compressed state.

The system can perform hermetic conditioning for two cases, depending on the initial levels of radioactivity of the ash residue loaded into the packaging:

– subject to loading of very low-activity ash residue, i.e. category “VLA”;

– subject to loading of low-activity ash residue, i.e. category “NAO”.

Before loading the ash residue intended for hermetic conditioning into the chute 6, at the outlet of the furnace bunker, in the place where the auger is located (not shown in the figure), a sensor checks the level of its radioactivity. After that, the operator, depending on the category of radioactive waste, selects the appropriate program for hermetic conditioning of the ash residue.

The first program with a standard scheme is intended for hermetic conditioning of the ash residue of the category "NAO", for which additional melting is not required. Under the control of this program, the system performs actions supplemented by the actions of the operator.

From the end of the housing 1, the gate valve of the gate opening 4 opens and the barrel 7 with the flexible package and two rubber rings inserted into it starts moving along the roller table 8 connected to the drive 9. The barrel 7, reaching the pneumatic cylinder 22 with the electromagnet 10, stops under it by a signal from the inductive sensors installed on the roller table 8. The pneumatic cylinder 22 with the electromagnet 10 performs a down-up cycle. In the lower position, the electromagnet 10 is triggered and the pneumatic cylinder 22 lifts the cover 21. The barrel 7 without the cover 21 continues to move along the roller table 8 to its final position and stops coaxially under the chute 6 according to the signals of the inductive position sensor fixed on the roller table 8. In this case, the emergency adjustable stops (not shown in the Fig.) are triggered on the roller table, preventing the barrel from shifting relative to the axis of the chute 6. The jaws 12, 13 of the sealing mechanism and the sections are moved apart to the final positions. Then the operator manually puts the upper part of the flexible package on the chute 6 through the glove openings 2 and fixes it with two rubber rings on it. Then, according to the signal from the sensors, the barrel is filled with ash. Ash residue is dosed into the chute 6 by means of a screw from the ash accumulation bin of the external furnace for incineration of radioactive waste (not shown in the Fig.).

The ash enters the flexible package placed in the barrel 7 and secured to the chute 6. The amount of ash is determined by the level sensors of the ash accumulation bin and visually by the operator. After filling the barrel 7 with ash residue, the operator switches off the auger, then switches on the mechanism for sealing and cutting the polyethylene radiation-resistant package. First, the sponge 13 without a knife is pulled out, then the sponge 12 with a knife. The heating elements of the sponges 12, 13 (not shown in the figure) are switched on and the package is sealed with two seams. At the moment when the package with the ash residue is sealed, the working stroke of the pneumatic cylinders of the knife of the sponge 12 occurs and the package is cut between the seams. The upper sealed part of the package, secured to the chute 6, remains on it and is subsequently removed into the next flexible package. Then the barrel 7 with the package pressed manually in it by the operator through the glove openings 2 moves along the roller table 8 to the position of removal and installation of the cover 21. The pneumatic cylinder 22 with the electromagnet 10 performs a down-up cycle, in the lower position the electromagnet 10 is switched off, the cover 21 remains on the barrel 7, and the pneumatic cylinder 22 returns to its original position. The door of the slide opening 4 opens and the barrel 7 is removed by the roller table 8 from the housing 1 for further technological operations.

Throughout the entire cycle, a system for cleaning from contaminants and radionuclides operates through nozzle 17, connected to a centralized special gas cleaning system located outside the working box.

The operator monitors the correctness of the dosing, loading, packaging and sealing process using lamps 20, illuminating the internal working area in the housing 1, a video camera located on the hatch of the process opening 18 and through viewing windows 3.

At the end of the sealing cycle, the decontamination system is switched on: through the nozzles 19 for the input and output of decontaminating solutions, a decontaminating agent is introduced, washing the inside of the housing 1, then through the same nozzles 19 the agent is output from the housing 1.

Maintenance of the system is possible through the mounting door 5.

The second program is designed for hermetic conditioning of the ash residue of the category "ONAO", which requires additional melting. Under the control of this program, the system performs actions supplemented by the operator's actions.

At the beginning of the program, the actions with barrel 7 and the actions for loading the ash residue into the flexible package of barrel 7 are repeated: barrel 7 installed on roller table 8 with a flexible package and two rubber rings inserted into it moves and stops coaxially under chute 6. After loading, barrel 7 moves to the melting zone, stopping at a position opposite muffle furnace 16. The operator opens muffle furnace 16 with manipulators 11 and removes the crucible from it with them. Then, using manipulators 11, the sealed package with ash residue from the barrel is loaded into the crucible, and then the crucible is transferred back to muffle furnace 16, where the process of additional melting of the ash residue is carried out. After additional melting, it is necessary to maintain the time required for cooling furnace 16 with the crucible to 60 °C. Upon reaching the specified temperature, the operator removes the crucible with the remelted ash residue from the furnace 16 using manipulators 11 and places it in the barrel 7. Then the barrel 7 with the crucible moves along the roller table 8 to the position of removing and installing the cover 21. The pneumatic cylinder 22 with the electromagnet 10 performs a down-up cycle; in the lower position, the electromagnet 10 is switched off, the cover 21 remains on the barrel 7, and the pneumatic cylinder 22 returns to its original position. The door of the slide opening 4 opens and the barrel 7 is removed by the roller table 8 from the housing 1 for further technological operations.

The operation of the package sealing and cutting mechanism based on the pneumatic system is as follows. After filling the flexible package in the barrel 7, compressed air is supplied to the pneumatic cylinder line of the jaw 13. The cylinder rod extends to its full length or until the position sensor is triggered. Then, compressed air is supplied to the second pneumatic cylinder line of the jaw 12, the cylinder rod extends until the jaws 12, 13 are connected. The heating of the jaws 12, 13 is switched on and the package is sealed. After sealing the package, compressed air is supplied via the third line to the pneumatic cylinder of the knife located on the jaw 12, as a result of which the rod extends and the package is cut between the sealing seams.

The hermetic ash residue conditioning system has been tested.

Thus, the design of the hermetic conditioning system for ash residue from the incineration of radioactive waste is simple to manufacture and assemble, reliable in operation, and has an increased level of radiation protection. In addition, in the proposed system, it is possible to perform hermetic conditioning in two ways depending on the initial levels of radioactivity of the loaded ash residue, as a result of which further alternative selection of the form of disposal of radioactive waste is possible, which has various technological and economic effects.

Claims (5)

1. A hermetically sealed conditioning system for ash residue from the incineration of radioactive waste, comprising a hermetically sealed work box consisting of a housing containing openings equipped with rubber gloves, a door driven by a drive, a radioactive material loading unit with manipulators, a container for radioactive waste with a lid, a platform for placing the container for radioactive waste, a control unit for the operation of the system located outside the box, a system for cleaning from contamination and radionuclides, a decontamination system located in the bottom part of the housing, a mechanism for installing the lid of the container for radioactive waste, characterized in that the housing has viewing windows, the door is made in the form of an opening with a slide valve, the container for radioactive waste with a lid is made in the form of a barrel with a flexible bag inside, the platform for placing the container for radioactive waste is made in the form of a controlled roller table, the mechanism for installing the lid of the container for radioactive waste is made in the form of a pneumatic cylinder with an electromagnet, in addition, the body of the work box contains an ash residue loading unit from a bunker having a radioactivity level monitoring sensor, containing a screw conveyor located outside the working box, connected to a loading chute for metered feeding of ash residue, said flexible package hermetically connected to the chute by rings via a glove post to prevent dusting during loading, a sealing unit and a flexible package cutter, made in the form of a pneumatic cylinder with a rod, with electrically heated pressure jaws located on it, one of which is equipped with a knife, drives with manipulators for the sealing unit and a flexible package cutter, nozzles and pipelines for removing contaminants and radionuclides and for creating a vacuum, connected to a centralized gas cleaning system located outside the working box, and an ash residue melting unit consisting of a muffle furnace with a crucible, located away from the roller table, equipped with manipulators. 2. The system according to item 1, characterized in that at least two openings equipped with rubber gloves are made in the housing. 3. The system according to item 1, characterized in that the body of the working box is equipped with at least two viewing windows. 4. The system according to item 1, characterized in that the flexible package is made of a polymer material. 5. The system according to item 1, characterized in that the drives of the roller conveyor, the sealing unit and the flexible package cutter, and the container lid installation mechanism are made remotely controlled.