RU194525U1 - LIQUID RADIOACTIVE WASTE PROCESSING PLANT - Google Patents

Abstract

The utility model relates to the field of liquid radioactive waste processing, and in particular to methods for concentrating liquid radioactive waste (LRW) by evaporation. Installation for processing LRW contains an evaporation tank connected to the tank with LRW and a condenser, a condensate collector, a heater and means of connection. The evaporation tank is located under the tank with LRW and connected to it and the condenser through the lid. The lid of the evaporator tank is fixedly mounted on the supporting frame. The evaporation tank is installed with the possibility of replacement in a heater located on the movement mechanism. The condensate collector is equipped with two nozzles, one for connecting to a vacuum system, the other for a sampler. The utility model allows to increase the productivity of the installation while maintaining radiation safety. 1 s.p. f-ly, 1 ill.

Description

The utility model relates to the field of liquid radioactive waste processing, namely, to methods for concentrating liquid radioactive waste (LRW), for example, obtained in the process of molybdenum-99 (Mo-99) extraction by evaporation.

Known utility model RU 60256, G21F 9/08, publ. January 10, 2007 “Installation for liquid radioactive waste processing”, which includes an oxidizer tank, a precipitator tank, a LRW pre-treatment unit, an intermediate tank, a concentrator consisting of an evaporator, a condenser, a cooler, a metering pump, an ion-selective filter, a concentrate tank, an evaporator and air conditioning unit. The LRW pretreatment unit consists of a LRW tank, a circulation pump, a control valve, a mixer, an oxidation unit, a shut-off valve, and a membrane filter. The oxidizer tank is connected to the mixer, and the precipitator tank is connected to the LRW tank. LRW capacity, circulation pump, control valve, mixer and oxidation unit are combined in a closed loop. LRW is supplied to the LRW tank, after filling it with the help of a circulation pump, LRW is circulated in a closed loop. Mixed with an oxidizing agent, the aqueous phase of LRW from a membrane filter is fed into an intermediate tank, where it is first analyzed for total activity, and then fed to a concentrator. The mechanical and colloidal phases of LRW are removed from the membrane filter using compressed air supplied to it and fed for curing. Concentrate (evaporate) in the LRW concentrator, after which the resulting concentrate passes successively through a cooler, a metering pump, an ion-selective filter, a concentrate tank, an evaporator, and a salt conditioning unit. The vapor phase from the concentrator enters the condenser, from where the condensate formed is sent to the discharge, since, thanks to the above preliminary processing of LRW, it does not require additional purification from radionuclides to meet the requirements of the current radiation safety standards. The disadvantages of this installation are:

- the complexity of the installation due to the presence of hydraulic machines (circulation pump, metering pump), which, including, reduce the life of the installation;

- the use of oxidizing agents and their treatment with ultrasound and ultraviolet increases the complexity of the evaporation process.

The utility model “Liquid Radioactive Waste Processing Unit” No. 1300127, G21F 9/00, published on July 10, 2013, which consists of a microwave installation, a radiation protection chamber, a container, a device for supplying radioactive waste, a device for collecting radioactive waste, a device for radioactivity control and steam filtration, conveyor belt. Using a conveyor belt, the container with radioactive waste is fed into the microwave chamber, where the liquid is evaporated and the radioactive waste is converted into solid form. The installation also contains a device for the removal of steam, in which it is radiation monitored, and, if necessary, filtered. All components of the installation are located in the radiation protection chamber. Next, there is a sampling of radioactive waste from the installation and steam output.

The disadvantages of the installation are:

- the inability to use metal tanks of LRW due to the evaporation process in the microwave chamber;

- the possibility of overheating of LRW and the difficulty of controlling the evaporation process, reducing safety during operation with the installation.

Closest to the proposed utility model is a plant for the processing of liquid radioactive waste (RU 2594568, G21F 9/08, publ. 08/20/2016), containing an evaporation tank connected to a tank with LRW, a condenser, a condensate collector, a heater and means of connection. As an evaporation tank, a cylindrical rotor-film evaporator with a jacket and with fittings for LRW input, discharge of concentrate and secondary steam, a rotor with blades fixed along its entire length is used. The installation comprises an LRW neutralization unit connected to a collection tank, a steam generator, a condensate drain line for primary steam, a separator and a condenser. The outlet for concentrate and secondary steam is located in the lower part of the evaporator. For the purpose of the initial air discharge at the start of the installation, the condensate drain line of the primary steam is equipped with an air collector with a wall contact thermometer to monitor the presence of air in the primary steam supply line. An electric steam generator is used as a heater. From the collection tank, LRW is fed to the solid phase separation unit and sent to a rotary-film evaporator (RPI). In EPI, the solution is smeared with blades on its inner surface and flows down in the form of a thin film. As the liquid film moves down, it warms up and evaporates. The resulting concentrate and the secondary steam move in the FIR from top to bottom and through the nozzle of the concentrate and secondary steam discharge enter the separator to separate the secondary steam from the concentrate. The heating of the RPI jacket is carried out with primary water vapor generated in an electric steam generator, which is filled with condensate (or distilled water). The primary water vapor from the steam generator is fed into the upper part of the EPI jacket, where, by condensing, it gives off heat to the heat exchange surface. Condensate drains into the lower part of the EPI shirt and then returns by gravity to the steam generator. The disadvantages of the known installation are:

- low productivity due to the low evaporation rate, since a rotary-film evaporator is used;

- the evaporation process can be complicated due to the formation of insoluble deposits on the walls of the rotary film evaporator, which also negatively affects the performance of the installation;

- complexity of installation.

The objective of the claimed utility model is to increase the productivity of the installation while maintaining radiation safety during the processing of LRW by evaporation.

When using the inventive installation, the following technical result is achieved:

- increases the productivity of the installation by reducing the complexity of the process of processing LRW while ensuring radiation safety.

To solve this problem and achieve a technical result, a plant for processing liquid radioactive waste (LRW) is declared, comprising an evaporation tank connected to a tank with LRW, a condenser, a condensate collector, a heater and a means of connection, in which, according to a utility model, the evaporation tank is located under receiving tank and connected to it through the lid and dispenser, and also connected through the lid to the condenser, while the evaporation tank is installed with the possibility of replacement in a heater located on the roystve displacement condensate collector is provided with two nozzles, one - for connection to a vacuum system, another - for the sampler.

The connection of the condensate collector with the vacuum system allows reducing the evaporation temperature in the LRW processing plant, which allows increasing the productivity of the evaporation process, increasing radiation safety, and the installation of the evaporation tank directly on the heater accelerates the LRW evaporation process, which also positively affects the plant performance. The dispenser allows you to regulate the flow of LRW from the tank with LRW into the evaporation tank, which contributes to the efficiency of the LRW processing process, since evaporation occurs in small portions, which allows you to control the process. It should be noted that the volume of the condensate collector is commensurate with the volume of the LRW tank, and when processing the entire volume of LRW located in the tank with LRW, the condensate enters the condensate tank, and the bottom residue remains in the evaporation tank. The lid of the evaporation tank is stationary mounted on the supporting frame, and the replacement of the evaporation tank is carried out using the manipulator after disconnecting it from the cover by the movement mechanism. The use of a moving mechanism and a manipulator for carrying out this operation excludes personnel contact with radioactive waste, which helps to increase the radiation safety of LRW processing at this facility. The evaporation tank must be disposed of, which eliminates the need for its subsequent decontamination. A positive factor for radiation safety is the ability to control the degree of condensate radioactivity in the condensate collector using a sampler, which determines its further disposal. The location of the evaporation tank under the tank with LRW, as well as the condenser above the condensate collector, allows the evaporation process to be carried out without the use of pumps, which increases the reliability of the installation and helps to ensure radiation safety.

A diagram of the inventive installation for processing liquid radioactive waste is presented in FIG. 1, where:

1. capacity with LRW;

2. evaporation capacity;

3. lid of the evaporation tank;

4. heater;

5. movement mechanism;

6. capacitor;

7. condensate collector;

8. dispenser;

9. pipelines;

10. frame;

11. a branch pipe for connection to a vacuum line;

12. a pipe for connecting a sampler;

13. radiation protection chamber;

14. the manipulator.

The installation for processing liquid radioactive waste is located in the radiation protection chamber 13, equipped with a manipulator 14. It contains a tank with LRW 1, a dispenser 8, an evaporation tank 2 with a lid 3, a heater 4, a condenser 6, a condensate collector 7 and connection means (pipelines) 9 The evaporating tank 2 is located under the tank with LRW 1 and is connected to it and the condenser 6 through the cover 3. The cover 3 of the evaporating tank 2 is fixedly mounted on the supporting frame 10. The evaporating tank 2 is installed in the heater 4 located on the movement mechanism I 5. The condensate collector 7 is equipped with two nozzles 11 and 12, 11 for connecting to a vacuum line, 12 for a sampler.

Installation works as follows.

The evaporation tank 2 is installed by means of the manipulator 14 into the heater 4, which is located on the movement mechanism 5. Using the movement mechanism 5, the evaporating vessel 2 is docked and undocked with a cover 3 fixedly mounted on the supporting frame 10. The unit is connected to the vacuum line through the pipe 11 in order to create a vacuum inside the installation. From the tank with LRW 1, through the dispenser 8, a portion of the initial LRW solution enters the evaporation tank 2. Heater 4 is turned on and the received portion of the LRW solution is evaporated. The gas phase of the liquid radioactive waste through the pipeline 9 is sent to the condenser 6, and the condensate enters the condensate collector 7. In the process of evaporation, coolant circulates through the cooling circuit of the condenser 6. After processing the first portion of LRW through the dispenser 8, the next portion of LRW enters the evaporation tank 2. The process is repeated until the tank is emptied with LRW 1. In this case, the condensate collector 7 is completely filled, because its volume is commensurate with the volume of the tank with LRW 1. Next, a condensate sample is taken through the sampling pipe 12. After receiving the analysis of radioactivity, a decision is made on its disposal (discharge into an industrial sewer, additional treatment, etc.). Using the manipulator 14 and the movement mechanism 5, the evaporator tank 2 is undocked with a cover 3, the evaporator tank 2 is replaced and disposed of.

The main components of the LRW processing facility (LRW tank, evaporation tank, condensate collector, condenser) are made of AISI 304 steel.

The inventive installation is quite simple to manufacture and maintain. An important factor in its use is radiation safety and a sufficiently high productivity of the LRW processing process.

Claims (2)

1. Installation for processing liquid radioactive waste, containing an evaporation tank connected to a tank with LRW and a condenser, a condensate collector, a heater and means of connection, characterized in that the evaporation tank is located below the tank with LRW and connected to it and a condenser through a lid, the lid of the evaporation tank is fixedly mounted on the supporting frame, and the evaporation tank is installed with the possibility of its replacement in the heater located on the movement mechanism, the condensate collector is equipped with two pipes, one for connecting to a vacuum system, another for a sampler. 2. Installation according to claim 1, characterized in that a dispenser is installed between the LRW tank and the evaporation tank.

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