KR102003980B1 - Facilities and method for system decontamination - Google Patents

Abstract

The present invention provides system decontamination facilities and a method thereof capable of minimizing radiation exposure of a worker. According to an embodiment of the present invention, the system decontamination facilities comprise: a chemical supply unit injecting chemicals into a system of a nuclear power plant; a filter unit connected with an exit of the system; a positive ion exchange resin connected with the filter unit; a reactor connected with the positive ion exchange resin; a cleansing solution tank connected with the reactor to clean the reactor; a mixed ion exchange resin connected with the reactor; and a circulation pipe unit connecting between the chemical supply unit, the filter unit, the positive ion exchange resin, the reactor, and the mixed ion exchange resin to form a circulation structure of a solution with the system.

Description

[0001] FACILITIES AND METHOD FOR SYSTEM DECONTAMINATION [0002]

The present invention relates to a plant decontamination facility and method, and more particularly, to a plant decontamination facility and method for chemical decontamination of a primary system at the time of dismantling a nuclear power plant.

Nuclear power plants artificially control the sequential fission reaction of fissile materials in the reactor to generate heat, produce radioactive isotopes and plutonium, or form radiation fields.

(Nuclear reactor pressure vessel, steam generator, pressurizer, main piping, etc.), chemical and volumetric control systems, and residual heat removal systems.

There is a radioactive material in this system, and the worker can be exposed to radiation.

Therefore, in order to reduce the radiation exposure of the dismantling worker due to the radioactive material immediately after the permanent suspension of the nuclear power plant, and to ensure the ease of dismantling and dismantling of the power plant, chemical system decontamination must be performed on the whole system contaminated with radioactivity .

One aspect of the present invention is to provide a systematic decontamination facility and method capable of easily decontaminating all systems and minimizing an operator's exposure when a nuclear power plant is dismantled.

A systematic decontamination facility according to an embodiment of the present invention includes a decontamination apparatus connected to a system of a nuclear power plant and supplying decontamination to a solution flowing through the system to decontaminate the system; A plurality of dose measuring devices installed in the system; And a control unit for receiving a real time dose measurement value from the plurality of dose measuring apparatuses and controlling the decontamination apparatus, wherein the decontamination apparatus forms a circulation structure of the system and the solution.

The dose measuring device may transmit the measured value to the controller through a wired or wireless communication.

The dose measuring device includes a position sensor and may transmit information of the installed position to the controller.

The decontamination apparatus may further include: a medicine supply unit for injecting the medicine into the solution; A filter unit connected to the system; A cation exchange resin connected to the filter portion; A reactor connected to the cation exchange resin; A mixed phase ion exchange resin connected to the reactor; And a circulation piping portion connecting the drug supply portion, the filter portion, the cation exchange resin, the reactor, and the mixed ion exchange resin to form a circulation structure of the solution together with the system.

Wherein the chemical supply unit includes an oxidant tank storing inorganic acid and permanganic acid; And a reducing agent tank in which the organic acid is stored.

The reactor includes a UV lamp that irradiates the solution through the interior with UV, and the UV lamp may include a plurality of lamps that emit UV of different wavelengths.

The decontamination apparatus may include a washing liquid tank connected to the reactor to wash the inside of the reactor; And a hydrogen peroxide tank for injecting hydrogen peroxide into the solution supplied to the reactor.

Wherein the decontamination apparatus further comprises a monitoring unit connected between the system and the filter unit, wherein the monitoring unit monitors pH, ORP (Oxidation-Reduction Potential) of the solution moving between the system and the filter unit, Potential), and a sensor for measuring electrical conductivity.

The control unit may compare the dose measurement value with a reference value to control the amount of the medicine injected from the drug supply unit.

The systematic decontamination method according to an embodiment of the present invention includes: transmitting positional information and a real-time dose measurement value to the control unit in the plurality of dose measurement apparatuses; And adjusting the supply amount of the medicine in the medicine supply unit by comparing the measured value of the real time dose with the reference value in the control unit.

And determining the decontamination area through the positional information and the real-time dose measurement value.

According to one embodiment of the present invention, chemical decontamination of the entire system at the time of nuclear dismantling can minimize the radiation exposure of the operator during disassembly work.

In addition, the degree of decontamination can be grasped in real time according to the position of the system, and the decontamination area can be grasped.

1 is a schematic view of a systematic decontamination facility according to an embodiment of the present invention.
2 is a flowchart illustrating a systematic decontamination method using a systematic decontamination facility according to an embodiment of the present invention.
3 is a configuration diagram of a systematic decontamination facility according to an embodiment of the present invention.
4 is a flowchart illustrating a systematic decontamination method according to an embodiment of the present invention.
FIGS. 5 to 10 are views for explaining the flow of the solution according to the systematic decontamination method of FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

1 is a schematic view of a systematic decontamination facility according to an embodiment of the present invention. For convenience of understanding, the system 100 is shown as a thick solid line in all the drawings including FIG. 1, but the system 100 is a concept including all the devices connected through piping including piping.

1, the systematic decontamination facility 10 includes a decontamination apparatus 1000, a plurality of dosimetry apparatuses 20, and a control unit 50.

The decontamination apparatus 1000 is connected to the system 100 of a nuclear power plant and supplies a chemical for decontamination to a fluid flowing through the system 100 (hereinafter referred to as a solution). Here, the system 100 can be a reactor coolant system (reactor pressure vessel, steam generator, pressurizer, main piping, etc.), a chemical and volume control system, a residual heat removal system, and can be made of metal including carbon steel or stainless steel . For example, the solution may be a primary system in which the radioactive material is circulated through the reactor. Thus, a metal oxide layer (chromium, iron, nickel, cobalt, etc.) may be formed on the inner surface of the system 100.

1, the decontamination apparatus 1000 may be connected such that a solution flowing through the system 100 circulates together with the decontamination apparatus 1000 and the system 100, as shown in FIG. For example, one side and the other side of the system 100 can be connected to the decontamination apparatus 1000, and the decontamination apparatus 1000 and the system 100 can form the circulation structure of the solution through the piping. Accordingly, the solution flowing through the system 100 can be decontaminated through the decontamination apparatus 1000 while mixing with the chemical and circulating the system 100.

The dose measuring device 20 may be an automatic dosimetry recorder (ADR) for measuring the dose of radiation, but it is not limited thereto and may include various kinds of dosimeters capable of measuring the dose in real time have. The dosimetry apparatus 20 may include a plurality of dosimeters and may be installed at various positions in the system 100. [ Thus, it is possible to measure the real time dose at the point where the dose measuring apparatus 20 is installed in the system 100. For example, the dose measuring apparatus 20 can measure the surface dose rate at a point where the dose measuring apparatus 20 such as a pipe in the system 100 is installed.

According to an embodiment of the present invention, the dose measuring device 20 may transmit information to the control unit 50, which will be described later, through wired or wireless communication. Accordingly, the dose measuring apparatus 20 may include a communication means for wired or wireless communication with the control unit 50, and may be configured to be capable of long distance wireless communication, for example. Accordingly, even if the operator does not go to the point where the dose measuring apparatus 20 is installed, the real-time dose value (for example, surface dose rate) The degree of progress of the decontamination process can be confirmed quickly, and the exposure of the operator can be prevented.

In addition, the dose measuring device 20 may include a position sensor capable of sensing position information of a point where the dose measuring device 20 is installed. Accordingly, the position information of the point where the dose measuring apparatus 20 is installed can be transmitted to the control unit 50, and the control unit 50 can grasp the real time dose by position in the system 100. Accordingly, in the process of decontaminating the system 100, the decontamination degree can be grasped in real time through the real-time dose measurement value. In addition, the degree of decontamination can be grasped in detail in the system 100 through the position information and the dose measurement value transmitted from the dose measuring apparatus 20. For example, there is an advantage in that it is possible to easily grasp the decontamination area (dead leg) where the decontamination in the piping in the system 100 is not proceeding properly. As will be described later, after the systematic decontamination process is completed, the decontamination section can be separately post-treated.

The control unit 50 receives the real-time dose measurement value from the dose measuring device 20 and controls the decanter 1000. The control unit 50 may be connected to the dose measuring device 20 and the decontamination apparatus 1000. The control unit 50 can receive the dose measurement values through the wired or wireless communication with a plurality of the dose measuring apparatuses 20 installed in the system 100. The control unit 50 compares the received dose measurement value with the reference value, Can be controlled. For example, depending on whether the dose measurement value reaches a reference value, which is a target value of decontamination completion, the chemical decontamination apparatus 1000 can stop the chemical injection, and in the decontamination process through the decontamination apparatus 1000, Or may control the number of cycles of the solution for the decontamination process.

2 is a flowchart illustrating a systematic decontamination method using a systematic decontamination facility according to an embodiment of the present invention. For example, in the decommissioning process of a nuclear power plant, a systematic decontamination method according to an embodiment of the present invention can be performed.

Referring to FIG. 2, the dose measuring device 20 measures a real time dose at an installation point (S11), and obtains position information of the installation point (S21). The control unit 50 controls the decontamination apparatus 1000 using the real-time dose measurement value in the dose measuring apparatus 20 (S12) (S22). ≪ / RTI > After the decontamination of the system is completed through the control of the decontamination apparatus 1000 (S13), the decontamination stationary zone can be post-processed using the decontamination stillness zone information obtained by the control unit 50 (S14).

For example, when proceeding to the decontamination process of the primary system in the disassembling process of the nuclear power plant, the average dose values are averaged by averaging the measured doses measured by the plurality of dose measuring apparatuses 20 installed in the system 100 And the derived average dose value can be treated as the dose value of the entire system 100. [ When the mean dose value reaches the target reference value during the system decontamination process, systematic decontamination may be deemed to have proceeded as desired, and the systematic decontamination process may be terminated. After completion of the system decontamination process, the equipment or piping determined as the decontamination stagnant zone may be separated from the system 100 by a method such as cutting, and then post-treated separately. For example, separate decontamination zones can be managed separately through instrument decontamination.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a systematic decontamination facility 10 and a decontamination apparatus 1000 according to an embodiment of the present invention will be described in detail.

3 is a configuration diagram of a systematic decontamination facility according to an embodiment of the present invention.

3, the decontamination apparatus 1000 includes a filter unit 200 connected to a system 100 of a nuclear power plant, a cation exchange resin 300 A reactor 400, a mixed-phase ion-exchange resin 500, a chemical supply unit 600, and a circulation piping unit 700 connecting the circulation piping unit 700 and the circulation piping unit 700.

The circulation piping unit 700 is connected to the system 100 and connects the filter unit 200, the cation exchange resin 300, the reactor 400, the mixed phase ion exchange resin 500, and the medicine supply unit 600 , Chemical decomposition of the system (100), organic acid decomposition of a solution containing a radioactive material, metal ion removal, and the like.

The circulation piping unit 700 includes a first circulation pipe P1 connected between the outlet of the system 100 and the filter unit 200 and a second circulation pipe P1 connected between the filter unit 200 and the cation exchange resin 300 A third circulation pipe P3 connected between the cation exchange resin 300 and the reactor 400, a fourth circulation pipe P3 connected between the reactor 400 and the mixed phase ion exchange resin 500, And a fifth circulation pipe P5 connected between the circulation pipe P4 and the mixed phase ion exchange resin 500 and the inlet of the system 100. [

The circulation piping unit 700 is branched from the fifth circulation pipe P5 and branches from the first branch pipe Y1 and the third circulation pipe P3 connected to the drug supply unit 600, A cleaning liquid tank 42 branched from the second branch pipe Y2, the third circulation pipe P3 and the fourth circulation pipe P4 connected to the hydrogen peroxide tank 41 for supplying hydrogen peroxide to the reactor 400, And a third branch pipe Y3 connected to the third branch pipe Y3.

The circulation piping unit 700 may further include a bypass pipe bypassing the device connected to the circulation pipe. The bypass pipe is connected between the second circulation pipe P2 and the third circulation pipe P3 to perform the cation exchange A first bypass pipe B1 bypassing the resin 300 and a second bypass pipe B2 connected to the fourth circulation pipe P4 and the fifth circulation pipe P5 to bypass the mixed phase ion exchange resin 500 And a third bypass pipe B3 connecting the third circulation pipe P3 and the fourth circulation pipe P4 to bypass the reactor 400. [

The circulation piping unit 700 may be provided with pumps (BP, PP1, PP2, PP3, PP4) and valves for controlling the speed and flow rate of the solution moving therein.

The sample pipes SP1, SP2, SP3, SP4, and SP5 may be provided in the circulation piping unit 700. The sample pipes SP1, SP2, SP3, SP4, May be respectively installed in the first circulation pipe (P1) to the fifth circulation pipe (P5). This enables precise monitoring of systematic decontamination and degradation purification processes.

The filter unit 200 removes the remaining particulate metallic material without dissolving in the solution discharged from the system 100 and transferred through the first circulation pipe P1. The particulate metallic materials of Cr, Ni, Fe, Co, Mn, and Cs having a size of 10 탆 or more are removed from the filter unit 200, The solution is transferred to the second circulation pipe (P2). At this time, the filter unit 200 may be a cartridge filter made of a corrosion-resistant material, and may have an efficiency of removing 98% or more of particles of 10 m or more.

The solution transferred to the second circulation pipe (P2) is transferred to the cation exchange resin (300) or the first bypass pipe (B1) according to the iron ion concentration of the solution through the pump (PP1).

The solution transferred to the cation exchange resin 300 may contain metal ions such as chromium (Cr), nickel (Ni), iron (Fe), cobalt (Co), manganese (Mn), cesium The solution is transferred to the third circulation pipe P3 and the solution transferred to the first bypass pipe B1 bypasses the cation exchange resin 300 and is transferred to the third circulation pipe P3.

At this time, the iron ion concentration of the solution transferred to the third circulation pipe P3 is kept at a reference value, for example, 2 mM or less, because the iron ion can be used as a catalyst in the reactor 400 in the photolysis. However, when the iron ion concentration exceeds 2 mM, iron in the solution may be deposited, so that the iron ion concentration is preferably 2 mM or less.

The solution can be collected through the second sample tube (SP2) and the third sample tube (SP3) for the measurement of the iron ion concentration. At this time, when the iron ion concentration measured through the second sample pipe (SP2) is 2 mM or less, the solution does not pass through the cation exchange resin 300 but flows through the first bypass pipe (B1) and the third circulation pipe To the reactor (400). On the other hand, when the ferrous ion concentration measured through the second sample tube (SP2) exceeds 2 mM, the solution passes through the cation exchange resin (300) to maintain the iron ion concentration at 2 mM or less (Via the third circulation pipe SP3) and then to the reactor 400 through the third circulation pipe P3.

Reactor 400 is the number of UV reactors containing UV lamps. When the solution is supplied into the reactor 400 from the upper side or the upper side of the reactor 400, an empty space may be formed on the reactor 400 to lower the reaction efficiency. Therefore, as in the embodiment of the present invention, the third circulation pipe P3 may be connected to the lower or lower side of the reactor 400. [

The UV generated from the UV lamp in the reactor 400 photodecomes the organic acid in the solution, at which time carbon dioxide gas and water may be generated. Therefore, an exhaust pipe 43 for discharging carbon dioxide gas may be connected to the upper part of the reactor 400.

The UV lamps in the reactor 400 may include a plurality of UV lamps that emit different wavelengths of UV light, for example, UVC lamps and UVB lamps. Since the UVB lamp is a high energy lamp compared to UVC, it is possible to mix UVB and UVC according to the reaction temperature in the reactor 400.

A temperature controller (not shown) such as a heater or a cooling unit may be installed outside the reactor 400.

Meanwhile, the reactor 400 may be connected to a sensor unit 44 for monitoring the internal reaction state in real time.

The sensor unit 44 measures temperature, pH, pressure, and the like in the reactor 400 so that the inside of the reactor 400 can maintain an optimum reaction environment. For example, when oxalic acid is decomposed with an organic acid, the optimum reaction temperature is 20 ° C to 50 ° C, so the internal temperature can be measured through the sensor unit 44 and the temperature can be maintained by adjusting the temperature control unit.

Depending on the oxalic acid concentration of the solution extracted through the fourth sample pipe SP4 installed in the fourth circulation pipe P4, the solution discharged from the reactor 400 is mixed with the mixed phase ion exchange resin 500 or the second bypass pipe B2 And then to the system 100 through the fifth circulation pipe P5.

The mixed phase ion exchange resin 500 may include a cation exchange resin and an anion exchange resin. The cation exchange resin removes metal ions remaining in the solution, and the anion exchange resin removes organic acids remaining in the solution.

The ratio of the cation exchange resin to the anion exchange resin may be mixed at a ratio of 5: 5, 6: 4, 7: 3, 8: 2 and may be changed according to the concentration of the organic acid passing through the mixed phase ion exchange resin.

The chemical supply unit 600 may include an oxidant tank 61 and a reducing agent tank 62. The oxidant tank 61 and the reducing agent tank 62 may be made of a chemical agent used as an oxidizing agent or a chemical agent used as a reducing agent, Tank. For example, the oxidizing agent may be a mineral acid such as nitric acid, sulfuric acid, hydrochloric acid and permanganic acid, and the reducing agent may be an organic acid such as oxalic acid, citric acid or citric acid and these may be stored in respective tanks and optionally supplied .

According to an embodiment of the present invention, the decontamination apparatus 1000 may further include a monitoring unit 800 positioned between the system 100 and the filter unit 200.

The monitoring unit 800 may include an electrical conductivity sensor, an ORP (Oxidation-Reduction Potential) sensor, a pH sensor, and a flow meter. The monitoring unit 800 may be connected to the system 100, Analyze the discharged solution.

The electrical conductivity sensor, the OPR sensor, and the pH sensor measure the conductivity, oxidation-reduction potential and hydrogen ion concentration index of the chemical decontamination agent, detect the electrochemical properties of the chemical decontamination agent, Process time and so on.

3, the monitoring unit 800 may be connected to the controller 50, and the monitoring unit 800 may monitor the dose measurement value and the positional information transmitted from the dose measuring device 20 in real time .

Hereinafter, the overall process of decontaminating the system 100 using the systematic decontamination facility described above will be described in detail.

FIG. 4 is a flow chart for explaining a systematic decontamination method according to an embodiment of the present invention, and FIGS. 5 to 10 are views for explaining a flow of a solution according to the decontamination procedure of FIG. 5 to 10, the configurations of the dose measuring device 20 and the control unit 50 are omitted.

Referring to FIG. 4, the systematic decontamination method according to an embodiment of the present invention includes an oxidant injection step (S100) for oxidation, a primary injection step (S102) for oxidizing decomposition and removal, a reducing agent 2 A car injection step (S104) and a purifying step.

The oxidation process according to the oxidant injection step (S100), the reducing agent first injection step (S102), the reducing agent secondary injection step (S104), the oxidant decomposition removal process and the reduction process proceed in the system (100) .

In the oxidant injection step (S100), the oxidant of the oxidant tank (61) is injected into the system (100) through the pump (PP2). At this time, the valve (VV) for controlling the movement of the solution to the first circulation pipe (P1) is in a closed state, and a solution such as a coolant is present in the system (100).

The oxidant is for removing the chromium oxide layer formed on the inner surface of the system 100 and may be heated after being heated through a heater (not shown) connected to the first branch pipe Y1. At this time, the oxidant is heated to a reaction temperature of 80 ° C to 100 ° C, and then is delivered to the fifth circulation pipe P5 through the pump PP2 and then injected into the system 100 through the booster pump BP . Since the system 100 maintains a constant pressure, the medicine is injected at a higher pressure than the system 100 through the booster pump BP.

The oxidizing agent may be injected with 50 ppm to 300 ppm permanganic acid and 0 to 5 mM inorganic acid, such as at least one of nitric acid, sulfuric acid and hydrochloric acid. As the reaction of oxidant permanganic acid progresses, the concentration of the oxidant changes and thus the pH increases. Thus, inorganic acids can be injected together to maintain the pH between 1.5 and 2.5.

When the oxidizing agent is injected into the system 100, the oxidation process proceeds in the process of Reaction 1 below, and the oxidation process may proceed for 3 to 24 hours. When the oxidation process time is less than 3 hours, sufficient reaction does not occur. When the oxidation process time exceeds 24 hours, the reaction process is not performed any more and the decontamination is not performed.

[Reaction Scheme 1]

In step S102, the reducing agent in the reducing agent tank 62 is injected into the system 100 through the pump PP2. When the reducing agent is injected, the oxidizer decomposition process proceeds. The oxidizing agent decomposition process proceeds in the process of the following Reaction Scheme 2 to decompose the permanganic acid remaining in the solution. At this time, 100 to 1,000 ppm of oxalic acid may be added to the reducing agent.

[Reaction Scheme 2]

Thereafter, in the second step of injecting the reducing agent (S104), an organic acid having a different concentration is further added to the system from the reducing agent tank 62, and the reducing step proceeds. Depending on the concentration, it can be stored in a reducing agent tank which is firstly charged and in a different reducing agent tank.

At this time, 1,000 to 3,000 ppm of oxalic acid is further added, and the reduction process proceeds to the process of Reaction Scheme 3 below, and the second injection is performed after 30 minutes to 1 hour after the first injection of the reducing agent.

[Reaction Scheme 3]

The reduction process may be performed for 4 to 72 hours, and the concentration of the metal ion is measured every one hour through the sample pipe SP1 provided in the first circulation pipe P1 (S106). If the concentration of the measured metal ion no longer changes, the reduction process is terminated.

The oxidation process in the system, the oxidizer decomposition process, and the reduction process are completed, and the valve VV is opened to discharge the solution in the system 100 to the first circulation pipe P1 to proceed the purification process. The purification process includes a step of removing particulate metallic material (S108), a step of removing metal ions (112), a step of decomposing oxalic acid (114), a circulation step of circulation (S117), and a step of removing residual oxalic acid and metal ions (S118), and includes all reaction processes that proceed from the system 100 as well as the system 100 after the reduction process.

In the particulate metallic material removal step (S108), the solution discharged from the system 100 is transferred to the filter unit 200 through the first circulation pipe P1, and the particles remaining in the solution by the filter unit 200 The metallic material is removed (S108). The particulate metal material may be Cr, Ni, Fe, Co, Mn, or Cs.

Thereafter, a sample of the solution passed through the filter unit 200 is sampled to measure the concentration of the iron ion (S108), and it is determined whether the concentration of the iron ion satisfies the reference value (S110).

The reference value of the iron ion concentration of the solution supplied to the reactor 400 is 2 mM or less, and when it exceeds 2 mM, iron may be deposited.

When the concentration of iron ions is within the standard value, the solution is transferred to the reactor 400 through the second circulation pipe P2, the first bypass pipe B1 and the third circulation pipe P3 (see FIG. 6).

On the contrary, when the concentration of the iron ions is out of the reference value, the solution passing through the filter unit 200 is passed through the cation exchange resin 300 to remove the metal ions (S112) so that the concentration of the iron ions can be within the standard value. When the solution passes through the cation exchange resin 300 and the concentration of the iron ion satisfies the reference value, the solution is transferred to the reactor 400 through the third circulation pipe P3 (see FIG. 7).

The cation exchange resin 300 is used to remove metal ions (Cr, Ni, Fe, Co, Mn, and Cs) in the solution. An appropriate amount of the cation exchange resin 300 is installed according to the concentration of the measured iron ions The iron ion concentration can be controlled. At this time, oxalic acid which is an organic acid can be regenerated.

The solution may be injected into the reactor 400 from the lower or lower side of the reactor 400 through a third circulation line P3 connected to the lower or lower side of the reactor 400. [

Meanwhile, the solution moves according to the iron ion concentration, and other metal ions remaining in the solution can be removed through the mixed phase ion exchange resin described later.

Hydrogen peroxide in the hydrogen peroxide tank 41 is injected into the reactor 400 through the second branch pipe Y2 and the third circulation pipe P3 in the oxalic acid decomposition step S114, Can be injected at a ratio of 1: 1 with oxalic acid while controlling the flow rate and the rate.

The oxalic acid decomposition proceeds to the process of the following [Reaction Scheme 4] due to the UV generated from the UV lamp installed in the reactor 400.

[Reaction Scheme 4]

The oxalic acid decomposition step (S114) proceeds while circulating in the reactor (400) and the system (100) (S117), and carbon dioxide is generated by the above reaction scheme (4). The generated carbon dioxide can be discharged to the outside through the exhaust pipe 43 connected to the upper part of the reactor 400.

On the other hand, when oxalic acid is decomposed, the optimum reaction temperature is 20 ° C to 50 ° C, so the internal temperature is measured through the sensor unit 44 and the temperature is maintained by adjusting the heater or the cooler.

The solution in the reactor 400 is sampled every hour through the sample tube SP4 to determine whether the resolution of oxalic acid satisfies a predetermined reference value (S116). At this time, the resolution standard value of oxalic acid can be predetermined to a specific value within the range of 90% to 99%.

The solution in the reactor 400 flows through the fourth circulation pipe P4, the second bypass pipe B2, the fifth circulation pipe P5, the system 100, the first circulation pipe P1 (See Fig. 8) circulating the filter unit 200, the second circulation pipe P2, the first bypass pipe B1, the third circulation pipe P3, and the reactor 400 ). The systematic cycle S117 can be repeated until the resolution of oxalic acid meets a criterion.

When the decomposition ability of oxalic acid is equal to or higher than the reference value, the step of removing residual oxalic acid and metal ions (S118) is performed.

The step of removing residual oxalic acid and metal ions S118 proceeds in the mixed phase ion exchange resin 500 and is transferred to the mixed phase ion exchange resin 500 through the fourth circulation pipe P4 and then to the fifth circulation pipe P5) (see Fig. 9). At this time, the valve provided in the second bypass pipe B2 is closed.

The mixed phase ion exchange resin 500 includes a cation exchange resin and an anion exchange resin for removing metal ions and oxalic acid remaining in the solution conveyed in the reactor 400. At this time, the ratio of the cation exchange resin and the anion exchange resin may be different depending on the concentration of the remaining oxalic acid. For example, the ratio of the cation exchange resin to the anion exchange resin may be 5: 5, 6: 4, 7: 3, 8: 2.

Thereafter, a decontamination factor (DF) is derived using a result obtained by measuring the surface dose rate of the piping or the like in the system 100, and it is determined whether the predetermined value of the DF is satisfied (S120). DF is a value derived by using a surface dose rate measurement value of a piping or the like, and a reference value of DF can be predetermined to a specific value in a range of 20 to 40.

According to an embodiment of the present invention, the surface dose rate of piping and the like in the system 100 can be measured in real time in the dosimetry apparatus 20 (see Figs. 1 and 3). The dose measuring device 20 is installed in various places in the system 100 to measure the surface dose rate at each installation point and compare the DF derived from the measured value with the reference value. For example, it is possible to derive an average value by averaging the measured values measured by the plurality of dose measuring apparatuses 20, and to derive the DF of the entire system 100 using the derived average value. The DF of the entire system 100 derived in this manner can be compared with a reference value to determine whether the systematic decontamination process is complete or not.

When the DF of the entire system 100 derived using the measured values measured in real time in the plurality of dose measuring apparatuses 20 is equal to or greater than a predetermined reference value, since the solution is a safe solution after the chemical decontamination process for the system 100, (100) or drained to the outside (S121). The solution can be sampled through a pre-drainage sample tube (SP5) and further analyzed for metal ions and organic acids.

On the other hand, even if the DF of the entire system 100 is higher than the reference value, the reference value may not be locally satisfied in the system 100. That is, depending on the position in the system 100, the DF in some zones may not satisfy the reference value. According to an embodiment of the present invention, even if the chemical decontamination process for the system 100 is finished, the decontamination area can be grasped in the system 100 using the position information of the plurality of dose measuring apparatuses 20 . Therefore, it is possible to separate equipment, piping, and the like, which are determined to be the decontamination stagnant zone, from the system 100 through a method such as cutting, and then post-treat them separately. For example, separate decontamination zones can be managed separately through instrument decontamination. In particular, after the chemical decontamination of the system is completed at the dismantling of the nuclear power plant, local decontamination of the apparatus can be performed to enhance the reliability of system decontamination.

Conversely, when the DF of the entire system 100 derived by using the measured values measured in real time in the plurality of dosimeters 20 is less than a predetermined reference value, the solution flows through the fifth circulation pipe P5 to the system 100, The decontamination step can be repeatedly carried out from the oxidant injection step S100 or the reducing agent secondary injection step S104 described above.

The oxidizing step of the oxidant injecting step S100 is for removing chromium in the system 100. When the chromium concentration deviates from the reference value, the oxidizing agent injecting step S100 proceeds from the oxidizing agent injecting step S100. When the chromium concentration satisfies the reference value, Since the step is not required, the decontamination step can be started from the step of injecting the reducing agent (S104).

At this time, the concentration of the chromium ion can be determined from the concentration measured in the metal ion concentration measuring step (S106), and the reference value of the chromium ion concentration can be 0 or more and less than 1 ppm.

On the other hand, as the process time in the reactor 400 increases, the metal ions in the solution are deposited on the surface of the UV lamp, and the efficiency of the reactor 400 deteriorates due to the deposited metal layer. Thus, the step of washing the reactor 400 (see FIG. 10) proceeds.

The washing of the reactor 400 can proceed as the reaction process proceeds in the system 100 or when the solution remains in the system 100. For example, when the solution remains in the system 100 during the oxidant injection step (S100), the reducing agent primary injection step (S102), the reducing agent secondary injection step (S104), or the system circulation (S117) .

In the washing step of the reactor 400, the washing liquid in the washing liquid tank 42 is injected into the reactor 400 through the pump PP4 to react with the metal on the surface of the lamp so that the metal can be eluted. The washing solution may be an inorganic or organic acid containing at least one of phosphoric acid, nitric acid, oxalic acid and citric acid.

After the valves of the third circulation pipe P3 and the fourth circulation pipe P4 connected to the reactor 400 are closed and the washing solution is injected into the reactor 400 through the third branch pipe Y3, So that the metal on the lamp surface can be removed while being circulated to the tank 43.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

10: system decontamination facility 20: dose measuring device
50: control unit 100:
200: Filter part 300: Cation exchange resin
400: UV reactor 500: mixed phase ion exchange resin
600: drug supply unit 800: monitoring unit
1000: Decontamination device

Claims (11)

The system is connected to one side and the other side of the nuclear power plant system and the one side is supplied with a medicine to the solution flowing through the system to decontaminate the system and the other side receives and dissolves the solution containing the medicine, A decontamination apparatus for forming a circulation structure of the solution together;
A plurality of dose measuring devices provided at an interval between the one side of the system and the other side and including a position sensor; And
And a control unit for controlling the decontamination apparatus to control the decontamination apparatus, wherein the control unit receives the positional information and the real-time dose measurement value from the plurality of dose measurement apparatuses by wire or wireless communication with the plurality of the dosimetry apparatuses, A control unit;
And a systematic decontamination facility. delete delete The method according to claim 1,
The decontamination apparatus comprises:
A drug supply unit for injecting the drug into the solution;
A filter unit connected to the system;
A cation exchange resin connected to the filter portion;
A reactor connected to the cation exchange resin;
A mixed phase ion exchange resin connected to the reactor; And
A circulation piping section connecting the chemical feed section, the filter section, the cation exchange resin, the reactor, and the mixed-phase ion exchange resin to form a circulation structure of the solution together with the system;
And a systematic decontamination facility. 5. The method of claim 4,
The medicine supply part
An oxidant tank storing inorganic acid and permanganic acid; And
A reducing agent tank storing an organic acid;
And a systematic decontamination facility. 5. The method of claim 4,
The reactor
And a UV lamp for irradiating the solution through the inside with UV,
Wherein the UV lamp comprises a plurality of lamps which emit UV of different wavelengths. The method according to claim 6,
The decontamination apparatus
A washing liquid tank connected to the reactor for washing the inside of the reactor; And
A hydrogen peroxide tank for injecting hydrogen peroxide into the solution supplied to the reactor;
Further comprising: a systematic decontamination facility. 5. The method of claim 4,
The decontamination apparatus
A monitoring unit connected between the system and the filter unit;
Further comprising:
Wherein the monitoring unit comprises a sensor for measuring pH, ORP (Oxidation-Reduction Potential), and electrical conductivity of the solution moving between the system and the filter unit. 5. The method of claim 4,
Wherein the control unit compares the dose measurement value with a reference value to control the amount of the medicine injected from the drug supply unit. 10. A systematic decontamination method using a systematic decontamination facility according to any one of claims 1 to 9,
Transmitting the position information and the real-time dose measurement value to the control unit in the plurality of dose measuring apparatuses; And
Controlling the decontamination apparatus by comparing the real-time dose measurement value with a reference value in the control unit;
Lt; / RTI > 11. The method of claim 10,
Determining a decontamination area through the positional information and the real-time dose measurement value;
Wherein the systematic decontamination method further comprises:

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