KR20110016681A - Continuous collecting system for radiocarbon from stack in pwr nuclear power plant's - Google Patents

Abstract

PURPOSE: A device for continuously collecting radiocarbon exhausted from a nuclear power plant is provided to accurately measure and analyze the density and amount of radioactivity by continuously collecting the gas sample exhausted from a nuclear power plant according to a chemical type. CONSTITUTION: A flow controller(11) controls the flow rate of a gas sample exhausted from an exhaust pipe of a nuclear power plant to the external environment. A tritium removal aeration bottle(12) is a GWC(Gas Washing Column) and removes tritium contained in the exhausted gas sample. The tritium removal aeration bottle is filled with deionized water to prevent the evaporation of NaOH that is a collecting solution. A catalytic reaction controller(15) is comprised of a flow meter, a digital timer, a temperature program controller, and a breaker. A continuous collecting device(10) includes a catalytic reactor(14). An organic type radiocarbon is collected in the collection aeration bottle via the catalytic reactor.

Description

Continuous collecting system for radiocarbon from stack in PWR nuclear power plant's}

The present invention relates to a continuous collection device of nuclear power plant exhaust port emission radiocarbon. More specifically, the present invention relates to various forms of radiocarbon compounds, which are contained in a small amount in the emission gas released into the environment through the light-water reactor nuclear power plant exhaust, in inorganic form ( ¹⁴ CO ₂ ) and organic form ( ¹⁴ CH ₄ ). The present invention relates to a continuous collection apparatus of nuclear power plant exhaust outlet radioactive carbon for measuring radioactivity on radiocarbon ( ^{1 4} C ) by means of a liquid scintillation counter after the separation and collection.

In the operation of nuclear facilities, radioactive materials in the liquid, gas, or solid state are generated. Basically, these radioactive materials are managed as radioactive wastes defined under the Atomic Energy Law. In principle, all solid radioactive waste generated in the radiation control area has been managed and disposed of as radioactive waste and non-radioactive waste through appropriate temporary storage steps. Liquid and gaseous radioactive waste is discharged into the environment under monitored and controlled conditions after appropriate treatment in accordance with the concept of authorized discharge. The effluents generated during the operation of nuclear power plants and discharged to the environment are monitored and controlled, but some gaseous radionuclides have been excluded due to their low generation or emission or no need for evaluation.

However, with the increase in the number of reactors operating in recent years, radiocarbon ( ^{1 4} C ) has recently emerged as a major concern for environmental emission management because of its unique characteristics unlike radionuclides ( ¹⁴ C ). come.

The radiocarbon ( ¹⁴ C ) has a long half-life of 5,730 years, as well as a maximum energy of β-rays emitted during decay of 156 keV, higher than 3H (triple water). The non-radioactive level of radiocarbon ( ¹⁴ C ) can be produced and changed by a number of factors, including the natural radiochemical reactions caused by the emission cosmic rays from nuclear power plants. It is known that the level of radioactivity in the general atmosphere is about 0.25 Bq per gram of carbon, and the radioactivity of radiocarbon ( ¹⁴ C ) in the atmosphere is in the form of hydrocarbon (14C _n H _m ) or carbon dioxide ( ¹⁴ CO ₂ ). ( ¹⁴ C ) is a type of radiocarbon ( ¹⁴ C ) that can be fixed in living organisms through respiration or carbon assimilation by copper, plants, and can accumulate in the human body through the food chain. More care and monitoring is required.

The characteristics of radiocarbon ( ¹⁴ C ), which are distinguished from other nuclear species produced during operation of a nuclear power plant, are characterized by a long half-life of 5,730 years and the possibility of accumulation in the human body by the food chain through respiration or carbon assimilation by plants and animals. Attention is drawn to trends in radiocarbon ( ¹⁴ C ) emissions and environmental impacts. In addition, the release of gaseous radiocarbon ( ¹⁴ C ) mixtures has resulted in the distribution of radiocarbons ( ¹⁴ C ) worldwide. Therefore, radioactive carbon ⁽¹⁴ C) to be produced and in order to examine and evaluate the characteristics of the radioactive carbon ⁽¹⁴ C) that are released into the environment by separating them with chemical typing for the sample to be measured established to capture technology .

In the related art, the tritium present in the atmosphere is collected by chemical type, for example, in the form of moisture tritium (HTO) and gaseous tritium (HTO), and at the same time, it collects radiocarbon ( ^{1 4} C ). The collecting device is registered and used in Korean Patent No. 100204187. As such, the collection device already developed and registered is a device for collecting radiocarbon ( ^{1 4} C ) without separating them into chemical forms (inorganic and organic).

In addition, another conventional technique of a similar method is a technique of collecting and analyzing radioactive carbon ( ^{1 4} C ) in the emission gas exiting through the exhaust port of the heavy water reactor nuclear power plant without chemical classification. These technologies can be described as a device for capturing only ¹⁴ CO ₂ without radiocarbon ( ^{1 4} C ). Although there may be some differences in the amount and emission chemistry of radiocarbon ( ^{1 4} C ) in nuclear power plants, the production mechanisms and emission types are similar. Thus, in the case of light water reactors, as in the heavy water reactors, not only ¹⁴ CO ₂ but also ¹⁴ CH ₄ , ¹⁴ CO and other hydrocarbons are discharged to the environment. However, in the case of the simultaneous collection of tritium and radiocarbon ( ^{1 4} C ) in the air and the collecting device applied to the heavy water channel, the inorganic material ( ¹⁴ CO ₂ ) is selected for analysis. To monitor radiocarbon ( ^{1 4} C ).

The radiocarbon ( ^{1 4} C ) concentration measurement method already in use can be said to determine the carbon radioactivity in the form of inorganic matter in the emission gas.

In order to measure the carbon in the form of inorganic matter and the carbon in the form of organic matter in the effluent flowing out through the air outlet of nuclear power plants, more accurate and highly efficient radiometry is required.

The present invention is to analyze the amount of radioactive carbon ( ¹⁴ C ) contained in the emission gas generated inevitably generated in addition to the operation of the nuclear power plant in the domestic light water reactor nuclear power plant and released into the environment through the exhaust port of the reactor building, fuel building, etc. In order to provide a continuous collection device of the nuclear power plant exhaust outlet emission radioactive carbon that can be continuously collected by separating the radioactive carbon ( ¹⁴ C ) in the form of organic matter and the radioactive carbon ( ¹⁴ C ) in the inorganic form present in the discharged gas discharged. The purpose is to.

The continuous capture device of the nuclear power plant exhaust port emission radiation carbon of the present invention,

A flow rate control unit configured to flow the discharge gas sample from the nuclear power plant exhaust port at a constant flow rate;

A tritium removal aeration bottle containing pure water to remove tritium contained in the discharge gas sample;

A collection aeration bottle containing an aqueous NaOH solution to collect radiocarbon ( ^{1 4} C ) in the form of an inorganic substance ( ¹⁴ CO ₂ ) from the discharge gas sample;

Catalytic reactor for converting non-captured organic carbon ( ^{1 4} C ) into inorganic carbon ( ^{1 4} C ); And

It is characterized by consisting of a catalytic reactor control unit for controlling the collection flow time and temperature of the discharge gas sample and to enable accurate catalysis.

The continuous collection device of the nuclear power plant exhaust outlet radioactive carbon ( ^{1 4} C ) of the present invention can continuously collect the nuclear power plant emission gas samples by chemical type, thereby being discharged to the environment from each building outlet of the nuclear power plant It is effective to calculate accurate measurement and analysis value of radiation concentration and amount of radiation.

Accordingly, there is an advantage that can be used as an important evidence for evaluating the radiation dose of the residents around the nuclear power plant and the impact of radiocarbon ( ^{1 4} C ) on the environment.

The present invention is a device for capturing radioactive carbon contained in the emission gas discharged from the nuclear power plant to the environment in the form of chemicals, for example, inorganic ( ¹⁴ CO ₂ ) and organic ( ¹⁴ CH ₄ ) to the outside from the nuclear power plant exhaust port It is connected to the exhaust duct which is discharged and collects the sample while flowing the discharge gas at a constant flow rate.

In the accompanying drawings, Figure 1 is an overall configuration diagram of the continuous collection device 10 of the nuclear power plant exhaust outlet radioactive carbon ( ^{1 4} C ) according to the present invention, Figure 2 is a nuclear power plant exhaust outlet radioactive carbon ( ^{1 4} according to the present invention) C ) is a front view schematically showing the continuous collecting device 10, and Fig. 3 is a rear view showing the internal structure thereof.

Here, reference numeral 11 denotes a flow control unit, 12 denotes a tritium removal aeration bottle, 13 denotes a radiocarbon aeration bottle, 14 denotes a catalytic reactor, 15 denotes a catalytic reactor control unit, 16 denotes a fan controller for cooling the device, and 17 denotes an aeration bottle. One gas is a condensate extractor, 18 is a power supply outlet, and 19 is a cooling fan to prevent the temperature rise of the unit to prevent the condensate from flowing into the power plant system when the temperature difference occurs.

The flow rate control unit 11 is to allow the sample to be collected while constantly flowing the flow rate of the gas sample discharged from the nuclear power plant exhaust port to the outside environment, as shown in Figs. 1 and 3, the gas inlet and outlet valves 111, a flow control power supply 112 is provided, the inside is composed of an air filter 113, a digital timer, a flow sensor 114, a mass flow controller, a diaphragm pump 115, a pressure gauge, etc. have. Therefore, the flow control unit 11 forcibly sucks the discharge gas to remove impurities that may be present in the discharge gas by the air filter 113, and then passes a constant flow rate through the mass flow controller. In this case, the current flow rate and the total accumulated flow rate are displayed on the flow rate indicator by using the signal from the mass flow controller. It is also equipped with a pressure gauge to determine whether to maintain a constant pressure using the diaphragm pump 115 to facilitate the intake and discharge of the flow rate, and the flow of liquid and gaseous fluid in the flow control unit 11 back flow To prevent this, a non-return valve is attached. In FIG. 1, reference numeral 20 denotes a discharge line.

The tritium removal aeration bottle 12 in the continuous capture device 10 of the present invention is a gas washing column (GWC) to remove tritium contained in the discharge gas sample and to prevent NaOH, which is a collection solution, from being evaporated by dry gas. In order to capture the radiocarbon ( ^{1 4} C ) in the form of inorganic and organic substances from the emission gas sample, the radiocarbon capture aeration bottle 13 is filled with 2M aqueous NaOH solution. In particular, the collection aeration bottle 13 is made of a chemical resistant material to withstand deformation due to the collection solution, as illustrated in FIG. 4, and in order to increase the collection efficiency of the radiocarbon, the discharge gas may pass through the collection solution. In order to allow the radiocarbon to generate an appropriate chemical reaction with the trapping solution, it is required to have a certain residence in the solution of the radiocarbon so that a polyethylene bubbler (131: Porosity 70 micro) can be used to generate fine air bubbles. A pivot valve 132 is installed inside the collection aeration bottle to prevent backflow due to a transient phenomenon in the emission gas sample collection aeration bottle, and a threaded bottle and a Teflon sealing cap 133 to facilitate attachment and detachment of the collection aeration bottle cap. ) Is installed. In FIG. 3, reference numeral 134 denotes a tube connector, and 135 denotes a DC power supply unit.

According to the continuous collecting device 10 of the present invention, the organic form ⁽¹⁴ CH _4), carbon-to inorganic form ⁽¹⁴ CO ₂₎ for collecting the radioactive carbon of the organic form ⁽¹⁴ CH ₄₎ as shown in Fig. 5 A catalytic reactor 14 for converting into radiocarbon is installed, and the filling and replacement of the catalyst are carried out by opening the connectors installed on both sides of the catalytic reactor. Threaded K-zone connector 141 is installed. The catalyst used in the present invention is filled with a catalyst (143) plated with platinum (Pt) on aluminum pellets, a catalyst 144 plated with palladium (Pd) on aluminum pellets in the quartz tube 145, which is used The organic material is oxidized at about 500 ° C. and converted to the inorganic form ( ¹⁴ CO ₂ ).

An additional collection aeration bottle is installed after passing through the catalytic reactor, and is filled with a solution of 2M NaOH to collect the organic form ( ¹⁴ CH ₄ ) in the inorganic form ( ¹⁴ CO ₂ ). Here, reference numeral 142 is a leak-proof fiber, 146 is a sealing cap.

According to the continuous capture device 10 of the present invention, the catalytic reactor controller 15 is a temperature program controller for controlling the heat source supplied to the flow meter, the digital timer and the catalytic reactor to adjust the collection flow time and temperature of the discharge gas sample It is composed of a power supply, which enables precise catalysis, prevents safety accidents caused by abnormal temperature of the catalytic device, and is equipped with a power cut-off device. Restoration mode is applied to check the time and total flow rate.

Referring to the capture mechanism using the continuous capture device of the nuclear power plant exhaust port emission radiocarbon ( ^{1 4} C ) of the present invention as follows.

According to the present invention, the capture of radioactive carbon ( ^{1 4} C ) from the gas discharged through the exhaust port of the nuclear power plant can be divided into two stages, the first stage is discharged from the aeration bottle 12 for removing tritium removal. The tritium contained in the gas is removed, and the radiocarbon ( ^{1 4} C ) is collected in the form of Na ₂ ¹⁴ CO ₃ in the radiocarbon capture aeration bottle 13.

The radiocarbon ( ^{1 4} C ) in the form of organic matter not collected in the first stage is then converted into ¹⁴ CO ₂ form while passing through the catalytic reactor 14 in the second stage and collected in a NaOH capture aeration bottle.

1 is an overall configuration diagram of a continuous collection device 10 of a nuclear power plant exhaust port emission radiocarbon ( ^{1 4} C ) according to the present invention.

Figure 2 is a front view schematically showing a continuous capture device of the nuclear power plant exhaust port discharge radioactive carbon ( ^{1 4} C ) according to the present invention.

3 is a rear view illustrating the internal structure of FIG. 2.

4 is a schematic diagram of a collection aeration bottle for collecting an emission gas sample in the present invention.

5 is a schematic view for showing the configuration of the catalytic reactor in the present invention.

<Description of the symbols for the main parts of the drawings>

10 ---- Continuous collection device of radiocarbon

11 ---- flow control

12 ---- tritium removal aeration bottle

13 ---- Radiocarbon Capture Aerator

14 ---- catalytic reactor

15 ---- catalytic reactor control unit

16 ---- Fan Controller

17 ---- lactation

18 ---- power supply outlet

19 ---- cooling fan

111 ---- Gas inlet and outlet valve

112 ---- Supply power supply for flow control

131 ---- polyethylene bubbler

132 ---- pivot valve

133 ---- teflon sealing cap

134 ---- tube connector

135 ---- DC power supply

141 ---- K-Zone Connector

142 ---- Leakproof Fiber

143 ---- Platinum (Pt) plated catalyst on aluminum pellets

144 ---- Palladium (Pd) plated catalyst on aluminum pellets

145 ---- quartz tube

146 ---- sealing cap

Claims (6)

A flow rate control unit configured to flow the discharge gas sample from the nuclear power plant exhaust port at a constant flow rate; A tritium removal aeration bottle containing pure water to remove tritium contained in the discharge gas sample; A collection aeration bottle containing NaOH aqueous solution for capturing radiocarbon in the form of an inorganic substance ( ¹⁴ CO ₂ ) from the discharge gas sample; Catalytic reactor for converting non-captured organic carbon ( ^{1 4} C ) into inorganic carbon ( ^{1 4} C ); And And a catalytic reactor control unit configured to control the collection flow time and temperature of the discharge gas sample and to perform accurate catalysis. The method of claim 1, wherein the collection aeration bottle is made of a chemical-resistant material, is equipped with a polyethylene bubbler to increase the collection efficiency, the interior of the inside to prevent backflow due to transients in the discharge gas sample collection aeration bottle Pivot valve is installed in the, and the capping bottle and Teflon sealing cap is installed so that the cap can be easily attached and detached. [Claim 2] The continuous collection apparatus of nuclear power plant exhaust outlet radiation carbon as claimed in claim 1, wherein the catalytic reactor is provided with K-zone connectors at both sides thereof for filling and replacement of the catalyst. The method of claim 3, wherein the catalyst is a catalyst in which platinum (Pt) plated aluminum pellets, a catalyst plated with a palladium plated aluminum pellets in a quartz tube filled with a continuous discharge of the carbon nuclear power plant exhaust port radiation characterized in that used Collection device. The method of claim 1, wherein the catalytic reactor oxidizing the radiocarbon ( ^{1 4} C ) in the form of organic matter at about 500 ℃ to convert into radiocarbon in the form of inorganic matter ( ¹⁴ CO ₂ ) nuclear power plant exhaust vent emission radiation carbon Continuous collection device. The reactor of claim 1, wherein an additional collection aeration bottle is installed at the rear end of the catalytic reactor, and a 2M NaOH solution is filled to collect radiocarbon in an inorganic form ( ¹⁴ CO ₂ ). Continuous collection device of radiation carbon.

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