KR101655061B1 - Method and Apparatus for Decontamination of Radioactive Metallic Wastes - Google Patents

Method and Apparatus for Decontamination of Radioactive Metallic Wastes Download PDF

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Publication number
KR101655061B1
KR101655061B1 KR1020160061445A KR20160061445A KR101655061B1 KR 101655061 B1 KR101655061 B1 KR 101655061B1 KR 1020160061445 A KR1020160061445 A KR 1020160061445A KR 20160061445 A KR20160061445 A KR 20160061445A KR 101655061 B1 KR101655061 B1 KR 101655061B1
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KR
South Korea
Prior art keywords
decontamination
foam
gas
solution
mixing tank
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KR1020160061445A
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Korean (ko)
Inventor
강덕원
김승일
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주식회사 금화피에스시
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/28—Treating solids
    • G21F9/30—Processing

Abstract

The present invention relates to a method and an apparatus for decontaminating radioactive metallic wastes. The method for decontaminating radioactive metallic wastes comprises a step of producing a decontamination solution, a step of generating foam, a step of decontamination, a step of reusing the decontamination solution, and a step of reusing gas. The present invention can autonomously treat the radioactive metallic wastes and recycle the radioactive metallic wastes as other materials by effectively decontaminating the radioactive metallic wastes by using the foam. In addition, the present invention has an effect of reusing the decontamination solution and gas used for decontamination by minimizing the generation of the decontamination waste water and waste gas.

Description

TECHNICAL FIELD The present invention relates to a decontamination method and a decontamination apparatus for radioactive metal waste,

The present invention relates to a decontamination method and a decontamination apparatus for radioactive metal waste, and more particularly, to a decontamination method and decontamination apparatus for waste radioactive waste, which are capable of efficiently discharging radioactive metal waste such as waste heat exchangers, waste steam generators, It is possible to self-treat radioactive metal waste and recycle radioactive metal waste to other materials, to minimize the generation of decontamination waste liquid and waste, and to use the decontamination solution and gas used for decontamination radioactive metal waste And a device therefor.

In the nuclear power plant, various aging equipment and parts are generated due to the periodical maintenance of large metallic equipment and the replacement of equipment due to the progress of operation training and the increase of operation nose. However, A method for treating a radioactive waste liquid generated in a reactor has not yet been established.

In addition to the steam generator, the heat exchanger, which is a typical large metal waste generated from a nuclear power plant, has a complex internal structure in the form of Shell & Straight Tube. In the tube side, seawater flows through the shell side.

Such heat exchangers are contaminated with trace amounts of radioactivity. Domestic nuclear power plants can not dispose of waste heat exchangers, which are complicated in internal structure and contaminated with trace amounts of radioactivity, and can be stored for long periods in a plant site or by blasting decontamination It is decontamination.

It is desirable to develop a decontamination method capable of effectively decontaminating such a large-scale metal waste, because such a radioactive contamination waste is desirably disposable to reduce the cost and disposal cost.

Concentrate Chemical Decontamination (CCD) and Dilute Chemical Decontamination (DCD) are methods for decontaminating such large metal waste. High concentration chemically resistant coatings are used to dissolve residuals from fission products and nuclear fuel fractures mainly due to the risk of corrosion of base materials and a large amount of waste liquid. Low concentration chemical coating methods are mainly used to compensate for these disadvantages.

The low concentration chemosynthetic method is advantageous in that the liquid waste is less generated and the process of mixing and draining and washing the reagents is not necessary, so that a large-capacity tank is not needed and the process proceeds quickly.

This low-level chemosynthetic process developed the CAN-DECON process using less than 0.1% decontamination agent to decontaminate the CANDU in early Canadian AECL. After that, Pacific Nuclear Sonic (PNS) of USA developed CITROX low concentration decontamination process using citric acid and oxalic acid.

In the UK, Berkeley Nuclear Laboratories (BNL) has developed LOMI (Low Oxidation-state Metal Ions) process, which is a soft decontamination process using picolinic acid and vanadium reductant, and applied it to the decontamination of heat exchangers and system equipment.

Siemens of Germany has developed the CORD / UV Decontamination Red-Violet (CORD / UV) decontamination process that minimizes the damage of the base material and produces less waste, and is widely used in Europe and Asia.

On the other hand, in a domestic thermal power plant, a foam cleaning method is used for cleaning a condenser, which is a device for reducing steam discharged from a turbine to water. The foam cleaning process is a process of (1) a foam cleaning process in which water is injected at a constant flow rate, foam is injected, and the amount of water, gas and foaming agent is adjusted so that the foam is completely filled up to the upper tube of the water chamber at the outlet of the condenser , (2) After reducing the flow rate used in the bubble cleaning process by 10%, add the hydrochloric acid, Ammonium Biflouride, corrosion inhibitor, etc. so that the bubbles can be completely filled up to the tube at the upper end of the condenser outlet water chamber. (3) a step of repeating the foam cleaning process; (4) a foam / soda cleaning process in which sodium carbonate is injected; and (5) To form a coating film.

As described above, the cleaning method using the bubbles can contact the portion to be cleaned for a sufficient period of time due to the nature of the bubbles, thereby improving the cleaning efficiency. In addition to the foaming agent for bubbles, There is an advantage that various decontamination agents can be applied.

However, in this method of purifying the bubble in the condenser, the flow rate of water is 204 to 306 m 3 / hr and the flow rate of the gas is 594 to 678 m 3 / hr. In this case, even though a large amount of water and gas is used, And the gas is discharged to the outside.

In the decontamination of large metal waste contaminated with radioactivity such as a steam generator or a heat exchanger, the decontamination solution and waste should not be released to the outside, and the amounts of decontamination waste and waste must be minimized. Therefore, It can not be applied to the decontamination of metal waste contaminated with water.

KR 10-0578227 B

The present invention efficiently decontaminates radioactive metal waste having a complicated structure such as a heat exchanger in which thousands of tubules are charged in decontamination of radioactive metal waste such as a steam generator and a heat exchanger generated in a nuclear power plant, And to provide a decontamination method and decontamination apparatus for radioactive metal waste that can minimize the occurrence of radioactive waste.

It is another object of the present invention to provide a decontamination solution used in decontamination of radioactive metal waste and a decontamination method and decontamination apparatus for radioactive metal waste which can reuse gas.

In order to achieve the above object, the present invention provides a method for decontaminating metal waste,

Preparing a decontamination solution by adding water, a foaming agent and a decontamination agent to the mixing tank; A foam generating step of injecting a gas supplied from a gas compressor and a decontamination solution prepared in the decontamination solution producing step into a foam generator to generate a foam; A decontamination step of adding the foam generated in the foam generation step to the decontamination salt to decontaminate the foam; A decontamination solution reuse step in which the decontamination solution generated in the foamed foam after being charged into the decontamination step in the decontamination step is stored in the treatment solution storage tank and then transferred to the mixing tank and introduced into the foam generator; And a gas reuse step in which the gas generated from the foam that has been destroyed after being charged into the decontamination salt in the decontamination step is compressed and stored and then introduced into the foam generator.

Meanwhile, the decontamination apparatus for metal waste according to the present invention comprises: a mixing tank for producing a decontamination solution with water, a foaming agent and a decontamination agent; A foam generator for generating bubbles from the decontamination solution supplied from the mixing tank and the gas supplied from the gas compressor, and supplying the generated bubbles to the decontamination water; A foam removing device installed at an outlet side of the decontamination product to destroy the foam; A treatment liquid storage tank installed below the decontamination product to store the decontamination solution generated from the foam that has been destroyed after being charged into the decontamination product and to transfer the decontamination solution to the mixing tank; And a water-sealed compressor for sucking the gas generated from the foam that has been destroyed after being charged into the decontamination water, compressing and storing the gas, and supplying the gas to the foam generator.

The present invention effectively decontaminates radioactive metal waste having a complex structure such as a heat exchanger in the decontamination of radioactive metal waste such as a steam generator and a heat exchanger generated from a nuclear power plant by using bubbles, It is possible to recycle to other materials, and the generation of the decontamination waste liquid and the waste material is minimized, and the decontamination solution and the gas used for decontamination can be reused.

1 is a flowchart of a waste decontamination process according to the present invention,
2 is a schematic block diagram of the entire process of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the decontamination method of the radioactive metal waste of the present invention comprises: a step (S1) of producing a decontamination solution by adding water, a foaming agent and a decontamination agent to a mixing tank; A foaming step (S2) of injecting the gas supplied from the gas compressor and the decontamination solution prepared in the decontamination solution preparation step (S1) into a foam generator to generate a foam; A decontamination step (S3) of charging the bubble generated in the bubble generating step (S2) into the decontamination water to decontaminate the bubble; A decontamination solution reuse step (S4) in which the decontamination solution generated in the bubble after being charged into the decontamination step (S3) in the decontamination step is stored in the treatment solution storage tank and then transferred to the mixing tank and charged into the foam generator; ; And a gas reuse step (S5) in which the gas generated from the foam that has been destroyed after being charged into the decontamination salt in the decontamination step (S3) is compressed and stored and then introduced into the foam generator.

Meanwhile, the decontamination apparatus for metal waste according to the present invention comprises a mixing tank 40 for producing a decontamination solution with water, a foaming agent and a decontamination agent; A foam generator 50 for generating bubbles from the decontamination solution supplied from the mixing tank 40 and the gas supplied from the gas compressor 60 and supplying the bubbles generated to the decontamination products 70; A foam removing device (80) provided at an outlet side of the decontamination product (70) to break foam; A treatment liquid reservoir 90 provided below the decontamination salt 70 for storing the decontamination solution generated in the foamed and broken foam after being charged into the decontamination product 70 and transferring the decontamination solution to the mixing tank 40; And a water-based compressor (100) for sucking the gas generated from the foam that has been destroyed after being input to the decontamination product (70), compressing and storing the gas, and supplying the gas to the foam generator (50).

In the decontamination solution preparation step (S1), a foam agent such as sodium laulyl sulphate which can generate bubbles, a decontaminating agent such as EDTA which is decontaminated by reacting with sediments (CRUD) adhering to metal waste, The mixture is introduced into the mixing tank 40 at a constant ratio and mixed to prepare a decontamination solution.

Preferably, the water, foam, and decontamination agent introduced into the mixing tank 40 are respectively controlled to be turned on and off by an automatic supplying device in accordance with a signal from the controller. In the mixing tank 40, It is desirable to install a sensing device such as a pH Sensor so as to be able to maintain the temperature.

A heater is provided in the mixing tank 40 so that the decontamination product 70 can be easily decontamined so that the temperature of the decontamination solution is 80 to 130 ° C and a temperature sensor is installed to control the heater in real time .

In addition, the concentration of the decontamination solution is measured in real time in the mixing tank 40, and when the concentration is decreased due to the reuse solution introduced through the solution reuse step (S4), the decontamination agent is automatically injected, do.

On the other hand, since the foaming agent used in the production of the decontamination solution affects the foaming property and the breaking property of the foaming agent, it is preferable to add 1 to 3 v / v% of foaming agent and 0.5 to 5 v / v% It is preferable to prepare a solution.

In the foam generating step S2, a decontamination solution in which water, a foaming agent, and a decontamination agent are mixed is introduced into the foam generator 50 from the mixing tank 40 and is supplied from the gas compressor 60 through a mass flow controller (MFC) To the bubble generating device (50). It is preferable that the MFC is supplied with a gas in a fixed amount, and a gas filter is installed in the MFC.

Also, since the physical properties of the foam such as the blow ratio, the size of the foam, and the half life of the foam are changed according to the ratio of the decontamination solution and the gas, the constant amount of the decontamination solution and the gas are always supplied.

The foam generator 50 is preferably constructed in such a manner that the impeller is rotated to generate foam by the rotation of the electric motor. Depending on the mechanical parameters of the foam generator 50 such as the number of revolutions and the number of impellers, Since the physical properties of the bubbles generated vary depending on the size, density, and the like of the bubbles, the inverter of the bubbler 50 can be mounted to easily adjust the number of rotations of the motor according to the state of the bubbles.

In addition, the foam produced in the foam generator 50 must remain stable until it reaches the outlet of the decontamination product 70, and the stability of the foam is greatly influenced by the mechanical parameters of the foam generator 50 The rotation speed of the electric motor of the foam generator 50 is appropriately adjusted so that the half life of the foam is 1 to 90 minutes.

In the decontamination step S3, the foam generated in the foam generation step S2 is introduced into the inlet of the decontamination product 70 such as a waste heat exchanger, a waste steam generator, etc., and the inside of the decontamination product 70 is filled with foam So that it is discharged to the outlet of the post decontamination product (70). Part of the foam introduced into the inlet of the decontamination product 70 starts to be destroyed from the time of introduction. At this time, the decontamination solution generated due to the destruction of the foam moves to the lower portion of the decontamination product 70 due to gravity, A treatment liquid reservoir (90) is provided below the decontamination product (70).

It is preferable that the inlet of the decontamination product 70 into which the foam is injected is installed at a position higher than the upper limit of the internal storage space of the decontamination product 70, A part of the piping at the outlet of the decontamination product 70 is made of a transparent material so as to change the rotation speed of the electric motor of the generator 50 and the composition of the decontamination solution and is discharged to the outlet side of the decontamination product 70 A foam removing device 80 capable of breaking the foam is installed.

In the bubbles which are destroyed in the defoaming device 80, the decontamination solution and the gas are generated at the same time, and the generated decontamination solution is transferred to the processing solution storage tank 90. The foam removal device 80, which breaks the foam in a mechanical manner, may be used, but is not limited thereto.

In the solution reuse step S4, the decontamination solution generated from the foam that is destroyed in the decontamination step S3 is transferred to the mixing tank 40 and then transferred to the foam generator 50 . The bubbles which have been destroyed in the inside of the decontamination product 70 after being put into the decontamination product 70 in the decontamination step S3 and the bubbles which have been destroyed by the defoaming device 80 installed on the outlet side of the decontamination product 70 The resulting decontamination solution is stored in the treatment liquid storage tank 90, transferred to the mixing tank 40, and introduced into the foam generator 50. It is preferable that the treatment liquid reservoir 90 is provided below the decontamination product 70.

A water level sensor is installed in the treatment liquid reservoir 90 so that when the decontamination solution reaches the constant water, the solenoid valve and the pump are automatically operated to be transferred to the mixing tank 40 until the sewage water reaches the sewage water. Since the used decontamination solution is transferred to the mixing tank 40 and then introduced into the foam generator 50, the decontamination solution is circulated and reused until the decontamination process is completed.

In the gas reuse step (S5), the gas generated from the foam that is broken down after being input to the decontamination product (70) is sucked, compressed, and reused. That is, the foam introduced into the decontamination product (70) is partially destroyed inside the decontamination product (70) and the rest is destroyed in the foam removal device (80) provided at the outlet side of the decontamination product (70).

The gas generated in the foam that is broken down after being input to the decontamination product 70 is sucked into the water-sealed type compressor 100 installed at the rear end of the foam removing device 80 and is stored by compression. After passing through the gas-liquid separator 110, the gas thus stored is introduced into the foam generator 50, and is circulated and reused until the decontamination process is completed. It is preferable to provide a flow detector for detecting the flow of the solution or gas at the downstream end of the defoaming device 80.

As described above, the present invention effectively decontaminates radioactive metal waste having a complex structure such as a heat exchanger in the decontamination of radioactive metal waste such as a steam generator and a heat exchanger generated from a nuclear power plant by using bubbles, The radioactive metal waste can be recycled to other materials, the generation of the decontamination waste liquid and the waste can be minimized, and the decontamination solution and the gas used for decontamination can be reused.

While the present invention has been described with reference to the exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but is capable of various changes and modifications within the technical scope of the invention. Therefore, the scope of the present invention is not limited by the above description.

Further, the reference numerals in the description and claims of the present invention are given for the purpose of facilitating understanding of the present invention, and the present invention is not limited to the drawings.

10: Water tank 20: Decontaminating tank
30: foam tank 40: mixing tank
50: foam generator 60: gas compressor
70: Disinfection water 80: Defoaming device
90: Process liquid storage tank 100: Water-containing type compressor
110: gas-liquid separator

Claims (11)

(S1) a step of preparing a decontamination solution by adding water, a foaming agent and a decontamination agent to the mixing tank;
A foaming step (S2) of injecting the gas supplied from the gas compressor and the decontamination solution prepared in the decontamination solution preparation step (S1) into a foam generator to generate a foam;
A decontamination step (S3) of charging the bubble generated in the bubble generating step (S2) into the decontamination water to decontaminate the bubble;
A decontamination solution reuse step (S4) in which the decontamination solution generated in the bubble after being charged into the decontamination step (S3) in the decontamination step is stored in the treatment solution storage tank and then transferred to the mixing tank and charged into the foam generator; ; And
And a gas reuse step (S5) in which the gas generated from the foam that has been destroyed after being charged into the decontamination salt in the decontamination step (S3) is compressed and stored in the foam generator,
Characterized in that when the decontamination solution reaches the constant temperature of the treatment liquid storage tank in the decontamination step (S3), the electromagnetic valve is automatically opened and the decontamination solution is transferred to the mixing tank until the pump is operated and reaches the sewage water. Decontamination of metal waste.

delete delete delete delete delete delete A mixing tank 40 for producing a decontamination solution with water, a foaming agent and a decontamination agent;
A foam generator 50 for generating bubbles from the decontamination solution supplied from the mixing tank 40 and the gas supplied from the gas compressor 60 and supplying the bubbles generated to the decontamination products 70;
A foam removing device (80) provided at an outlet side of the decontamination product (70) to break foam;
A treatment liquid reservoir 90 provided below the decontamination salt 70 for storing the decontamination solution generated in the foamed and broken foam after being charged into the decontamination product 70 and transferring the decontamination solution to the mixing tank 40;
(100) for sucking the gas generated from the foam that has been broken after being input to the decontamination product (70), compressing and storing the gas, and supplying the gas to the foam generator (50)
Wherein a gas-liquid separator (110) is installed between the water-pump type compressor (100) and the foam generation device (50).

delete 9. The method of claim 8,
Wherein an MFC (mass flow controller) is installed in the gas compressor (60) so that gas is constantly supplied from the gas compressor (60).
9. The method of claim 8,
Characterized in that a heater is provided in the mixing tank (40) so that the temperature of the decontamination solution is maintained at 80 to 130 ° C, and a temperature sensor is installed to control the heater in real time.
KR1020160061445A 2016-05-19 2016-05-19 Method and Apparatus for Decontamination of Radioactive Metallic Wastes KR101655061B1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101979876B1 (en) 2018-10-15 2019-05-17 허종구 scaffold pipe

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0815490A (en) * 1994-06-29 1996-01-19 Ngk Insulators Ltd Method and device for decontaminating metal waste
JPH09159798A (en) * 1995-12-12 1997-06-20 Jgc Corp Bubble decontamination and method for treating decontamination waste liquid
KR100578227B1 (en) 2003-12-30 2006-05-12 두산중공업 주식회사 Radioactivity Removing Apparatus of Radioactive Metal
JP2009125684A (en) * 2007-11-26 2009-06-11 Toshiba Corp Water treatment apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0815490A (en) * 1994-06-29 1996-01-19 Ngk Insulators Ltd Method and device for decontaminating metal waste
JPH09159798A (en) * 1995-12-12 1997-06-20 Jgc Corp Bubble decontamination and method for treating decontamination waste liquid
KR100578227B1 (en) 2003-12-30 2006-05-12 두산중공업 주식회사 Radioactivity Removing Apparatus of Radioactive Metal
JP2009125684A (en) * 2007-11-26 2009-06-11 Toshiba Corp Water treatment apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101979876B1 (en) 2018-10-15 2019-05-17 허종구 scaffold pipe

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