KR20200123675A - Method for Analyzing Radionuclide and Apparatus for Analyzing Radionuclide - Google Patents

Abstract

The present invention relates to a method and a device for analyzing a radionuclide. The method of the present invention comprises: a step (A) of preparing a sample containing Fe-55 and Ni-59; a step (B) of converting X-rays generated from the Fe-55 and Ni-59 contained in the sample into electric charges, and obtaining an X-ray-derived energy spectrum of the Fe-55 and Ni-59 by performing detection with at least one X-ray detector for measuring the intensity of photon energy by using silicon as a mediator when the electric charges are moved to a drift electric field; and a step (C) of determining radioactivity of the Fe-55 and Ni-59 contained in the sample from the obtained X-ray-derived energy spectrum of the Fe-55 and Ni-59. The device of the present invention comprises: a first storage container for storing a sample containing Fe-55 and Ni-59 therein; at least one X-ray detector disposed at a certain distance from the first storage container, converting X-rays generated from the Fe-55 and Ni-59 contained in the sample into electric charges, and obtaining an X-ray-derived energy spectrum of the Fe-55 and Ni-59 by detecting the intensity of photon energy using silicon as a mediator when the electric charges are moved to a drift electric field; and a measuring unit for determining radioactivity of the Fe-55 and Ni-59 contained in the sample from the obtained X-ray-derived energy spectrum of the Fe-55 and Ni-59. Accordingly, the method and device of the present invention can be used even at room temperature without cooling by using liquid nitrogen.

Description

Radionuclide analysis method and radionuclide analysis apparatus {Method for Analyzing Radionuclide and Apparatus for Analyzing Radionuclide}

The present invention relates to a radionuclide analysis method and a radionuclide analysis apparatus, and specifically, a technology for analyzing Fe-55 and Ni-59, which are radionuclides contained in radioactive solid waste, before storage and disposal of radioactive solid waste. It is about.

Radioactive waste that is inevitably generated in the process of using nuclear power or dismantling a nuclear power plant must ultimately be permanently isolated from the ecosystem. At this time, the disposal method differs depending on the radioactivity (Bq) of the radioactive waste, and the disposal cost differs from several times to several dozen times. In particular, among radionuclides contained in radioactive waste, quantitative analysis of Fe-55 and Ni-59 is essential.

Previously, in order to separate two types of nuclides from concrete and soil (radioactive waste) containing Fe-55 and Ni-59, after alkali melting, liquid scintillation counter (LSC), through chemical separation, Analysis was performed using a low energy germanium detector (LEGe) or a silicon lithium semiconductor detector (Si(Li) semiconductor detector).

However, in the chemical separation process, which is the next step after the alkali melting process that can dissolve concrete or soil materials, additional organic solutions are required because the separation is performed through the process of adding a chemical solution, and a lot of time is required for separation at that stage. It is required, and there is a problem that secondary radioactive waste such as organic waste liquid is generated. And for LSC measurement, an organic solvent, LSC-cocktail, is used to mix and measure the sample to be analyzed. At this time, the organic waste liquid is generated in a ratio of about 1 to 1 with the sample to be analyzed for radioactive waste. There is a problem in that an organic waste solution containing as many radionuclides as the number of samples to be analyzed for radioactivity that can have representativeness representing radioactive wastes is generated, and the waste solution is classified as a liquid radioactive waste.

In addition, Fe-55 and Ni-59 are radionuclides that emit low-energy X-rays, and Fe-55 and Ni-59 exhibit X-ray emission peaks in the energy bands adjacent to each other. In the case of using an LSC, LEGe, or Si(Li) semiconductor detector, the resolution (resolution) of the peak in the energy spectrum derived from X-rays emitted from Fe-55 and Ni-59 is low, making it impossible to separate the two nuclides. there is a problem.

In addition, since LEGe or Si(Li) semiconductor detectors must use liquid nitrogen to maintain a low temperature for sufficient conductivity and good resolution, problems arise when used at room temperature, and additional equipment such as liquid nitrogen tanks are provided. And there is a limit to the miniaturization of equipment due to the need to manage.

Therefore, it takes a lot of time and manpower to analyze a large amount of concrete or soil radioactive waste generated when the nuclear facility is dismantled with the above conventional detector, and it has a problem that must be used at low temperatures (cooling of liquid nitrogen, etc.). Therefore, since the detector is frequently replaced, there are various inconveniences such as the need for additional personnel.

The present invention is to solve the above problems, and can be used at room temperature without a cooling step using liquid nitrogen, and to provide a method for analyzing radionuclides without generation of secondary radioactive waste such as organic waste liquid. .

Furthermore, since the peaks of the two nuclides on the energy spectrum obtained by detecting X-rays generated from Fe-55 and Ni-59 do not overlap each other and are clearly distinguished, the qualitative and quantification of Fe-55 and Ni-59 contained in radioactive waste. To enable analysis.

According to an embodiment of the present invention, (A) preparing a sample containing Fe-55 and Ni-59; (B) Converting X-rays generated from Fe-55 and Ni-59 contained in the sample into electric charges, and measuring the intensity of photon energy using silicon as a medium when the electric charges move in a drift electric field Obtaining an X-ray-derived energy spectrum of the Fe-55 and Ni-59 by detecting with at least one X-ray detector; And (C) determining the radioactivity of Fe-55 and Ni-59 contained in the sample from the X-ray-derived energy spectrum of the obtained Fe-55 and Ni-59; a method for analyzing a radionuclide comprising Provides.

In addition, according to another embodiment of the present invention, a first storage container for storing a sample containing Fe-55 and Ni-59; It is disposed at a certain distance from the first storage container, converts X-rays generated from Fe-55 and Ni-59 contained in the sample into electric charges, and uses silicon as a medium when the electric charges move in a drift electric field. At least one X-ray detector for obtaining an X-ray-derived energy spectrum of the Fe-55 and Ni-59 by measuring the intensity of photon energy; And a measuring unit for determining the radioactivity of Fe-55 and Ni-59 contained in the sample from the X-ray-derived energy spectrum of the obtained Fe-55 and Ni-59; do.

According to the method for analyzing radionuclides according to the present invention, an X-ray detector that converts X-rays to electric charges and measures the intensity of photon energy using silicon as a mediating material when the electric charges move in a drift electric field is used. Thus, the two nuclides can be quantitatively and qualitatively analyzed from the energy spectrum derived from X-rays generated from Fe-55 and Ni-59 at room temperature without a cooling process using liquid nitrogen without generating secondary radioactive waste such as organic waste. As possible, it is possible to replace the detector due to the use of liquid nitrogen in a liquid scintillation counter (LSC) that was used as an X-ray detector in the past, a low-energy region germanium detector (LEGe), or a Si (Li) semiconductor detector. It is possible to overcome the hassle of operation and the problem of taking a lot of time and manpower in analyzing concrete or soil containing a large amount of radionuclides, and it is composed of a miniaturized system as it does not require additional management facilities such as liquid nitrogen maintenance equipment. This is possible.

Accordingly, it is possible to increase analysis efficiency by arranging several miniaturized equipment at the same time, or to continuously analyze (i.e., applied to an automated process) by arranging them in a series, thereby increasing the efficiency to analyze a single sample. The analysis time of Fe-55 and Ni-59 from the nuclide-containing sample can be shortened.

1 is a diagram showing an X-ray-derived energy spectrum emitted from Fe-55 using the X-ray detector of the present invention.
2 is a diagram showing an energy spectrum derived from X-rays emitted from Ni-59 using the X-ray detector of the present invention.
3 is a diagram showing a result of measuring the energy spectrum derived from X-rays emitted from a sample containing Fe-55 and Ni-59 according to an embodiment of the present invention by SDD.
4 is a schematic diagram showing a 3D rendered image of a sample and an X-ray detector automated system according to an embodiment of the present invention, and an arrangement of the system.
FIG. 5 is a diagram showing a result of measuring an X-ray-derived energy spectrum emitted from a sample containing Fe-55 and Ni-59 according to the prior art with a LEGe detector.

Hereinafter, the present invention will be described in detail.

1. Radionuclide analysis method

The present invention provides a method for analyzing radionuclides.

The method for analyzing radionuclides of the present invention comprises the steps of: (A) preparing a sample containing Fe-55 and Ni-59; (B) Converting X-rays generated from Fe-55 and Ni-59 contained in the sample into electric charges, and measuring the intensity of photon energy using silicon as a medium when the electric charges move in a drift electric field Obtaining an X-ray-derived energy spectrum of the Fe-55 and Ni-59 by detecting with at least one X-ray detector; And (C) determining the radioactivity of Fe-55 and Ni-59 contained in the sample from the energy spectrum derived from X-rays of the obtained Fe-55 and Ni-59.

In the step (A), the sample containing Fe-55 and Ni-59 may be a precipitate obtained by melting the radioactive solid waste containing Fe-55 and Ni-59 and then precipitating the molten radioactive solid waste. The precipitate (sample) may have a diameter of about 3 to 5 cm and a thickness of 10 to 50 µm.

In addition, for higher analysis efficiency and reduction of analysis time, the precipitate may be placed in direct contact with the X-ray detector after sealing (prevention of contamination of the X-ray detector) to analyze radionuclides. have.

In particular, as described above, the method of analyzing radionuclides of the present invention does not use a liquid scintillation counter (LSC) and introduces a sample pretreatment method of a precipitation method, so that organic waste liquid is not generated at all.

That is, the method of analyzing the radionuclides may be that secondary radioactive waste including organic waste liquid is not substantially generated, and the meaning of that secondary radioactive waste including organic waste liquid is not substantially generated means that the organic waste liquid is It may be generated in a small amount so as not to generate any secondary radioactive waste containing or to affect the detection of the X-ray-derived energy spectrum of the Fe-55 and Ni-59.

In the step (B), the X-ray detector converts X-rays generated from Fe-55 and Ni-59 contained in the sample into electric charges, and uses silicon as an intermediary material when the electric charges move in a drift electric field. By measuring the intensity of photon energy by using the X-ray-derived energy spectrum of the Fe-55 and the Ni-59 can be obtained.

The X-ray detector may include a silicon-based semiconductor detector. In the semiconductor detector, when charges (or ionized particles) generated by X-rays enter the semiconductor detector, an electron-positive pair is generated, and the electrons and positive holes move to the electrode along the electric field to create an electrical signal (photon energy). . Since the energy required to generate an electron-positive pair is 10 times less than the energy required to generate an electron-ion pair, the above semiconductor detector generates more charged particles than the gas detector for the same amount of particle energy. Energy resolution can be improved.

The X-ray detector may use high-purity silicon as an intermediary material. In addition, the X-ray detector may include a flat cathode and a series of electrodes having a concentric circle and an anode forming a small circle at the center. Accordingly, charges (or ions) generated by X-rays generated from the Fe-55 and Ni-59 draw a concentric circle. The concentric series of electrodes form a drift electric field that moves charges, and the charges are collected to the center anode, and the anode with a small area maintains a very small capacitance to reduce electronic noise, resulting in improved resolution. (About 123 to 135 eV FWHM at 4 µs peaking time @ 5.9 keV).

Si(Li) or Ge(Li) semiconductor detector diffuses Li into p-type Si or p-type Ge to form a pn junction to increase the thickness of the depletion layer, and then applies a reverse voltage to flow lithium (Li) ions. It is formed by adding an intrinsic semiconductor part called i-layer (intrinsic region) between p-type and n-type by (drifting) it. As above, lithium is used as a medium to move (or flow) charges. In order to maintain the lithium flow correction region or prevent the diffusion of the drifted lithium ions at room temperature, it must be cooled to liquid nitrogen temperature for storage and use.

However, since the X-ray detector used in the present invention uses silicon instead of lithium as an intermediary material, it is not necessary to include a cooling process such as liquid nitrogen temperature. That is, the means that the method for analyzing radionuclides may not substantially include the step of cooling using liquid nitrogen, and that the step of cooling using liquid nitrogen is substantially not included. This may mean that the step of cooling with nitrogen does not have to be performed at all.

The method of analyzing the radionuclide may be performed at 5 to 30°C, specifically 10 to 30°C, and more specifically 15 to 25°C. That is, the method of analyzing the radionuclide may be performed at room temperature.

Specifically, the X-ray detector may include a Silicon Drift Detector (SDD) among silicon-based semiconductor detectors.

On the other hand, looking at the X-ray-derived energy spectrum obtained by detecting each of Fe-55 and Ni-59 independently with the X-ray detector, Fe-55 is 5.6 to 6.0 keV and 6.2 to 6.6 keV as shown in FIG. The energy spectrum derived from X-rays can be obtained in the energy band, and as shown in FIG. 2, the energy spectrum derived from X-rays can be obtained for Ni-59 in the energy bands of 6.7 to 7.0 keV and 7.4 to 7.8 keV.

Specifically, Fe-55 exhibits X-ray emission peaks in the energy bands of 5.9 keV and 6.5 keV, and Ni-59 exhibits X-ray emission peaks in the energy bands of 6.9 keV and 7.7 keV.

It is not easy to separate the two radionuclides (Fe-55, Ni-59) that show the peaks in the adjacent energy bands through conventional radiation detectors (for example, LSC, LEGe, Si(Li) semiconductor detector). , X-ray-derived energy spectrum is measured by detecting X-rays emitted from Fe-55 and Ni-59 of the Fe-55 and Ni-59-containing samples with the X-ray detector according to the method for analyzing radionuclides of the present invention. Then, it can be seen that a total of four peaks can be accurately distinguished as shown in FIG. 3.

In addition, in the (C) step, the step of determining the radioactivity of Fe-55 and Ni-59 contained in the sample from the X-ray-derived energy spectrum of Fe-55 and Ni-59 obtained in the (B) step, After determining the measurement efficiency of the X-ray detector through detector calibration using a standard radionuclide with known radioactivity, the counting rate of a specific peak region in the energy spectrum obtained when measuring with the X-ray detector for an unknown sample (per second Measured value), the measurement efficiency determined previously and the probability of decay of the radionuclide (Fe-55 or Ni-59) to be measured (a radionuclide (Fe-55 or Ni-59) can decay and emit X-rays of specific energy). It can be carried out through a method of calculating the total amount (Bq) of radioactivity emitted from Fe-55 or Ni-59 contained in the sample by dividing it by the multiplied value).

The standard radionuclide is a radionuclide that knows the radioactivity contained in the nuclide, and is not limited thereto as long as it is a radionuclide guaranteed by a manufacturing organization (NPL, Ekert & Zigler, etc.) for a standard source for radioactivity. For example, 1 mL of a Ni-59 Certified Reference Material (CRM) having a concentration of 100 Bq/g is diluted with 9 ml of distilled water that does not contain radioactive isotopes, and finally 1,000 Bq of Ni-59 Can be used as a sample.

The measurement efficiency is an index used when determining the detector characteristics of the X-ray detector (SDD) through a standard radionuclide with known radioactivity, and when measuring X-rays generated from the standard radionuclide with the X-ray detector , The value obtained by measuring the number of X-ray photons (counts per sec.(cps)) entering the counter during a unit time is the product of the radioactivity of the standard radionuclide and the probability of decay of the radionuclide energy of the standard radionuclide. It means the percentage (%) of the value divided by.

In addition, the method for analyzing radionuclides of the present invention includes the steps of (A1) preparing a sample containing Fe-55 and Ni-59 contained in a first storage container; (B1) At least one X-ray converting X-rays generated from Fe-55 and Ni-59 contained in the sample into electric charges, and measuring photon energy using silicon as a mediating material when the electric charges move in a drift electric field Obtaining an X-ray-derived energy spectrum of the Fe-55 and Ni-59 by detecting with a ray detector; And (C1) after determining the radioactivity of Fe-55 and Ni-59 contained in the sample from the energy spectrum derived from X-rays of the obtained Fe-55 and Ni-59, the first storage container is transferred to the outside, The cycle including the step of replacing the sample containing Fe-55 and Ni-59 with a second storage container accommodated may be repeatedly performed at regular time intervals.

According to the method for analyzing radionuclides of the present invention, since cooling to liquid nitrogen temperature is not required, liquid nitrogen-related equipment is not required, and since organic waste liquid is not generated in the analysis process, related equipment that needs to treat organic waste liquid is also As equipment can be miniaturized, it is possible to repeatedly perform radionuclide analysis by applying it to a series of automated processes as described above, thereby shortening the analysis time of radionuclides and increasing analysis efficiency. .

Specifically, in step (C1), the first storage container may be replaced with the second storage container arranged in a series with the first storage container. The first storage container and the second storage container may contain samples containing Fe-55 and Ni-59 that are the same or different from each other.

As shown in FIG. 4, a transfer means may be used to replace the first storage container with the second storage container, and the transfer means transfers the first storage container to the outside at regular time intervals, and 1 The storage container can be replaced with the second storage container. The transfer means may be used without being limited thereto as long as it can transfer the first storage container, and specifically, may be a retractor, a vehicle, a movable belt, an automatic towing robot, etc., but is not limited thereto. Preferably the conveying means may comprise a moving belt. The movable belt may specifically be a conveyor belt, a plate belt, or the like, but is not limited thereto.

That is, in the transfer means, the first storage container and the second storage container may be arranged in a series.

The first storage container may use a vial made of polyolefin or a filter. The polyolefin may include at least one selected from polyethylene, polypropylene, polyisopropylene, polybutylene, and mixtures thereof, but is not limited thereto. The filter may include a glass microfiber filter. The glass fiber filter may include a filter having a pore size of 1 to 1.5 µm, preferably 1.2 µm, and may include, for example, a Whatman's GF/C (pore size: 1.2 µm) filter.

When a filter other than a vial is used as the first storage container, a polypropylene film may be used to protect the surface of an unknown sample accommodated in the filter and to prevent contamination of the X-ray detector.

The X-ray detector may have a distance of 20 mm or less from the first storage container. In addition, the Fe-55 and Ni-59-containing samples (precipitates) are placed in direct contact with the X-ray detector after the sealing (prevention of contamination of the X-ray detector) as described above to prevent radionuclides. You can also analyze it.

In addition, the at least one X-ray detector may be a plurality of X-ray detectors spaced at regular intervals. For example, one X-ray detector SDD may be disposed above and/or below one sample, but a plurality of X-ray detectors (SDD) above and/or below one sample ( SDD) may be disposed, and if a plurality of X-ray detectors are disposed at the same position from the sample (first storage container), it is not limited thereto.

2. Radionuclide analysis device

The present invention provides an apparatus for analyzing radionuclides.

The radionuclide analysis apparatus comprises: a first storage container for storing samples containing Fe-55 and Ni-59; It is disposed at a certain distance from the first storage container, converts X-rays generated from Fe-55 and Ni-59 contained in the sample into electric charges, and uses silicon as a medium when the electric charges move in a drift electric field. At least one X-ray detector for measuring the intensity of photon energy to obtain an X-ray-derived energy spectrum of the Fe-55 and Ni-59; And a measuring unit for determining the radioactivity of Fe-55 and Ni-59 contained in the sample from the energy spectrum derived from X-rays of the obtained Fe-55 and Ni-59.

In particular, the apparatus for analyzing radionuclides of the present invention does not have to be equipped with equipment related to cooling liquid nitrogen or equipment related to organic waste liquid treatment, so that the equipment can be miniaturized, so it can be applied to a series of automated processes to repeatedly perform radionuclide analysis. have.

Accordingly, the radionuclide analysis device transfers the first storage container containing the Fe-55 and Ni-59-containing samples to the outside at regular time intervals, as shown in FIG. 4, so that the first storage container is Fe -55 and Ni-59-containing samples may further include a transfer means for replacing with the received second storage container.

As described above, since the X-ray detector uses silicon, not lithium, as an intermediary material, it may not include a cooling process such as liquid nitrogen temperature, and accordingly, the method of analyzing the radionuclide may be performed at 5 to 30°C. And, specifically, it may be performed at 10 to 30 ℃, more specifically 15 to 25 ℃. To this end, the radionuclide analysis device may further include a temperature control unit.

The measurement unit may determine the radioactivity of Fe-55 and Ni-59 contained in the sample from the energy spectrum derived from X-rays of the Fe-55 and Ni-59. The method for determining the radioactivity of Fe-55 and Ni-59 contained in the sample is described in '1. The same can be applied to the above information in'Method of analyzing radionuclides'.

In addition, the X-ray detector may include a silicon-based semiconductor detector as described above, and the X-ray detector may use high-purity silicon as an intermediary material.

The X-ray detector may not include a cooling process such as liquid nitrogen temperature because silicon is used as an intermediary material among silicon-based semiconductor detectors, and thus, the radionuclide analysis device includes a cooling member using liquid nitrogen. It may not be substantially included. The meaning of substantially not including the cooling member may mean that the radionuclide analysis apparatus does not need to include the cooling member at all.

Specifically, the X-ray detector may include a Silicon Drift Detector (SDD), a distance from the first storage container to the X-ray detector may be 20 mm or less, and the at least one X-ray detector is spaced apart at regular intervals. It may be a plurality of X-ray detectors.

In addition, the Fe-55 and Ni-59-containing sample, the first storage container, and the X-ray detector are '1. The same can be applied to the above information in'Method of analyzing radionuclides'.

As described above, in the case of using the radionuclide analysis apparatus according to the present invention, a cooling member using liquid nitrogen is not required while secondary radioactive waste including organic waste is not generated, and thus a miniaturized system can be configured. In addition, as quantitative and qualitative analysis is possible from the energy spectrum derived from X-rays generated from Fe-55 and Ni-59 at room temperature, organic waste liquid is generated in the liquid scintillation counter (LSC) used as an X-ray detector. Solving the problem, and the hassle of replacing the detector due to the use of liquid nitrogen in the low energy domain germanium detector (LEGe) or Si(Li) semiconductor detector, and a lot of time and manpower in analyzing concrete or soil containing a large amount of radionuclides. You can overcome the required problems.

Furthermore, it is possible to increase the analysis efficiency by placing several miniaturized devices (X-ray detectors) at the same time, or to analyze them continuously (i.e., applied to an automated process) by placing them in series, so the efficiency to analyze one sample is improved. As a result, the analysis time of Fe-55 and Ni-59 from samples containing radionuclides can be shortened.

Hereinafter, before performing the qualitative/quantitative analysis of Fe-55 and Ni-59 of unknown radioactive solid waste, a specific method of calculating the measurement efficiency of the X-ray detector using a standard radionuclide of known radioactivity (Bq) is described. Described.

For example, after alkali melting a mixture of standard radionuclides (standard radionuclides of base radioactivity (Bq)) of Fe-55 and Ni-59, a carrier in 5 mL of 0.2% nitric acid solution in a 15 mL tube for centrifugation. It can be prepared by adding 2 mg of iron and nickel each, and then adding Fe-55 and Ni-63 respectively. For the mixed solution, close the lid and shake well, and then add 4 M sodium hydroxide solution to increase the pH between 8 and 9. Thereafter, the precipitates are allowed to stand at room temperature for about 30 minutes so that the precipitates mature well, and then the precipitates having a diameter of 2 cm and a maximum thickness of 50 μm can be separated using a Whatman GF/C (pore size: 1.2 μm) filter. After the separated filter is dried, a sample can be prepared by wrapping it with a polypropylene film (thickness: 0.2 μm) to protect the surface and prevent contamination of the detector.

The energy spectrum derived from X-rays measured using the SDD (XR-100 Fast SDD-70), an X-ray detector of the present invention, for the sample is shown in FIG. 3.

Using the sample prepared above, the counting rate (count per unit time) was measured by measuring the number (count) of X-ray photons of Fe-55 and Ni-59 entering the SDD counter at room temperature, and a standard radionuclide. Divided by the product of the radioactivity (Bq) of and the probability of decay of the energy of radionuclides in each energy region of Fe-55 and Ni-59 (see Equation 1 below), and the above in each energy region of Fe-55 and Ni-59 SDD measurement efficiency can be calculated.

<Calculation 1>

(Where, A: radioactivity (Bq), CPS: counting rate, ε: SDD detector measurement efficiency, γ: radionuclide energy decay probability)

The probability of decay of radionuclides energy in each energy domain of Fe-55 and Ni-59 can be obtained from Monographie BIPM-Table of Radionuclides Vol. 3, page 5 and Vol. 6, page 7 as theoretical values.

The measurement efficiency of SDD calculated above may have an error depending on the radioactivity of the standard radionuclide, the probability of radionuclide energy decay, the number of measurements, etc., and the measurement efficiency (corrected value) obtained through the calibration process may be used to reduce such errors. .

Using this measurement efficiency (corrected value), qualitative analysis and quantitative analysis of unknown radioactive solid waste can be performed using the SDD.

Specifically, for the radioactive solid waste, when the energy spectrum derived from X-rays is measured using the SDD, an X-ray detector of the present invention, if the energy spectrum as shown in FIG. 3 is obtained, Fe- It can be seen that it contains 55 and Ni-59.

Next, the number (count) of X-ray photons of Fe-55 and Ni-59 entering the SDD counter at room temperature for the radioactive solid waste is measured for a certain period of time to determine the counting rate (count per unit time). It is calculated and divided by a value obtained by multiplying the measurement efficiency of SDD calculated in advance and the probability of decay of the energy of radionuclides in each energy region of Fe-55 and Ni-59, and Fe contained in the radioactive solid waste through the above calculation formula 1 The radioactivity (Bq) derived from each energy region of -55 and Ni-59 can be measured.

In particular, in the case of using the X-ray detector (SDD) of the present invention, it can be confirmed that the peaks in the respective energy domains do not overlap but appear as four clearly separated radioactive solid wastes containing Fe-55 and Ni-59. In the case of measurement using an existing LEGe detector (ORTEC, GLP-36360/13), it can be confirmed that the energy spectrum peaks derived from X-rays overlap each other, as shown in FIG. 5, and accordingly, the X-ray detector It can be seen that the process of separating Fe-55 and Ni-59 nuclides must be performed before the analysis through the analysis.

That is, according to the method and apparatus for analyzing radionuclides of the present invention, the peaks for each energy region of the two nuclides in the X-ray-derived energy spectrum without prior separation of Fe-55 and Ni-59 contained in radioactive solid waste are visually observed. Also clearly distinguished, qualitative analysis and quantitative analysis was possible with only a single measurement. It was confirmed that this is because the X-ray detector according to the present invention has superior resolution (resolution) of the X-ray-derived energy spectrum peaks of Fe-55 and Ni-59 compared to conventional detectors.

Claims (16)

(A) preparing a sample containing Fe-55 and Ni-59;
(B) Converting X-rays generated from Fe-55 and Ni-59 contained in the sample into electric charges, and measuring the intensity of photon energy using silicon as a medium when the electric charges move in a drift electric field Obtaining an X-ray-derived energy spectrum of the Fe-55 and Ni-59 by detecting with at least one X-ray detector; And
(C) determining the radioactivity of Fe-55 and Ni-59 contained in the sample from the energy spectrum derived from X-rays of the obtained Fe-55 and Ni-59;
The method of analyzing a radionuclide comprising a. The method according to claim 1,
The sample containing Fe-55 and Ni-59 is obtained by melting the radioactive solid waste containing Fe-55 and Ni-59 and then precipitating the molten radioactive solid waste. The method according to claim 1,
The X-ray detector is a radionuclide analysis method comprising a SDD (Silicon Drift Detector). The method according to claim 1,
The method for analyzing radionuclides does not substantially include cooling using liquid nitrogen. The method according to claim 1,
The method of analyzing the radionuclide is a method of analyzing a radionuclide that does not substantially generate secondary radioactive waste containing organic waste liquid. The method according to claim 1,
In the step (B), the energy spectrum is obtained by detecting with a plurality of X-ray detectors spaced at regular intervals. The method according to claim 1,
(A1) preparing a sample containing Fe-55 and Ni-59 accommodated in a first storage container;
(B1) At least one that converts X-rays generated from Fe-55 and Ni-59 contained in the sample into electric charges, and measures the intensity of photon energy using silicon as a mediating material when the electric charges move in a drift electric field Obtaining an X-ray-derived energy spectrum of the Fe-55 and Ni-59 by detecting with an X-ray detector of; And
(C1) After determining the radioactivity of Fe-55 and Ni-59 contained in the sample from the X-ray-derived energy spectrum of the obtained Fe-55 and Ni-59, the first storage container was transferred to the outside, and Fe A method for analyzing radionuclides, wherein a cycle comprising the step of replacing the sample containing -55 and Ni-59 with a second storage container accommodated is repeatedly performed at regular time intervals. The method of claim 7,
In the step (C1), the method of analyzing a radionuclide by replacing the first storage container with the second storage container arranged in a series with the first storage container. The method of claim 7,
The method of analyzing radionuclides in which the distance from the first storage container to the at least one X-ray detector is 20 mm or less. A first storage container for storing samples containing Fe-55 and Ni-59;
It is disposed at a certain distance from the first storage container, converts X-rays generated from Fe-55 and Ni-59 contained in the sample into electric charges, and uses silicon as a medium when the electric charges move in a drift electric field. At least one X-ray detector for measuring the intensity of photon energy to obtain an X-ray-derived energy spectrum of the Fe-55 and Ni-59; And
A measuring unit for determining radioactivity of Fe-55 and Ni-59 contained in the sample from the energy spectrum derived from X-rays of the obtained Fe-55 and Ni-59;
A radionuclide analysis device comprising a. The method of claim 10,
The first storage container containing the Fe-55 and Ni-59-containing samples is transferred to the outside at regular time intervals, and the first storage container is replaced with a second storage container containing the Fe-55 and Ni-59-containing samples. The radionuclide analysis apparatus further comprising a transport means for making. The method of claim 11,
The transport means is the radionuclide analysis apparatus in which the first storage container and the second storage container are arranged in a series. The method of claim 10,
The X-ray detector is a radionuclide analysis device comprising a SDD (Silicon Drift Detector). The method of claim 10,
The radionuclide analysis apparatus substantially does not include a cooling member using liquid nitrogen. The method of claim 10,
A radionuclide analysis apparatus wherein the distance from the first storage container to the at least one X-ray detector is 20 mm or less. The method of claim 10,
The at least one X-ray detector is a radionuclide analysis apparatus that is a plurality of X-ray detectors spaced at regular intervals.

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