KR20140062292A - The measuring method of nuclear material by nuclear fission reaction by neutron and low temperature detector, and the device thereof - Google Patents
The measuring method of nuclear material by nuclear fission reaction by neutron and low temperature detector, and the device thereof Download PDFInfo
- Publication number
- KR20140062292A KR20140062292A KR1020120128795A KR20120128795A KR20140062292A KR 20140062292 A KR20140062292 A KR 20140062292A KR 1020120128795 A KR1020120128795 A KR 1020120128795A KR 20120128795 A KR20120128795 A KR 20120128795A KR 20140062292 A KR20140062292 A KR 20140062292A
- Authority
- KR
- South Korea
- Prior art keywords
- temperature detector
- neutron
- nuclear material
- low temperature
- foil
- Prior art date
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/17—Circuit arrangements not adapted to a particular type of detector
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/30—Measuring half-life of a radioactive substance
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- High Energy & Nuclear Physics (AREA)
- Molecular Biology (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Measurement Of Radiation (AREA)
Abstract
Description
The present invention relates to a neutron-assisted fission reaction, a nuclear material measurement method using a low-temperature detector, and a device used therefor.
Radionuclides decay with a certain half-life and turn into other nuclides, which release various types of radiation. These are alpha particles, beta rays (electrons or positron), neutrinos, gamma rays, x-rays, and the like. These particles are emitted by the decay of nuclei or by the transitions of electrons excited around the nucleus. These particles, which occur during decay, have an intrinsic energy spectrum that can be determined by measuring these energy spectra.
The difference between the mass of the radionuclide and the mass of all the particles generated after the collapse occurs. The mass difference before and after the collapse, ie, the lost mass, is converted into energy and distributed to the kinetic energy and photon energy of the individual particles generated at the time of collapse. Depending on the atoms of the radionuclide, the mass loss after collapse is set to a unique value, usually called the intrinsic Q-value of the nuclide. Of course, even if the Q-value is fixed, the alpha or gamma rays generated by various decay channels have a wide spectrum of energy. The Q-value range of alpha decay is between about 2 MeV and 11 MeV.
Since all radionuclides have a unique Q-value for radioactive decay, the nuclides can be determined by measuring all the energy sums, or Q-values, occurring during the decay process. When applied to the measurement of nuclear material (U, etc.) using this principle, the Q-value of alpha decay can be measured to detect the nuclear activity, illegal transaction of nuclear material and terrorism surveillance, environment monitoring of high level radioactive waste repository, Nuclear fuel processing and production facilities), and uranium in the environment.
Thermal ionization mass spectrometry (TI-MS) is the best available technology for measuring nuclear materials. It is a method of measuring the mass / charge ( m / z ) Analysis to determine the content of isotopes. Resolution and sensitivity. When the fission track detector technique and the enrichment technique using ionized water are applied together, U can be measured up to ng (10 -9 g). However, according to the above method, there is a problem that such a pretreatment process must be performed.
Neutrons can be used to detect nuclear material, for example, a fission track detector technique can be used. This method is a method in which a sample having a nuclear material leaves a fission track on a plastic when a small amount of a sample containing a very small amount of nuclear material is placed between plastics and put into a reactor having a high neutron flux, . This has the advantage that it is excellent in confirming the presence of a nuclear substance in a trace amount of a sample. However, there is a problem in that the above method can not quantify the existing nuclear material.
Neutron activation analysis can also be used. After neutrons are irradiated by sending a sample to the vicinity of the core of a research reactor with a high neutron flux, the nuclear material is measured by measuring gamma rays or delayed neutrons emitted from the sample. According to the above method, quantification of an existing nuclear material can be performed. In addition, the sensitivity of the measurement and the signal to noise ratio (S / N ratio) are improved when measuring the spurious neutron.
A method of measuring a nuclear material using alpha spectroscopy can be used. This is a technique for measuring the amount of nuclear material through the spectroscopy of alpha particles emitted from nuclear material. At this time, a semiconductor detector using ionization of a substance by alpha particles is mainly used for measurement of alpha particles. In the alpha particle measurement, the detector is placed outside the sample as in FIG. 1 (a), and the alpha particles that exit the sample and enter the detector are measured. However, according to this method, only a part of the released alpha particles can be measured because the detector occupies a certain solid angle with respect to the sample. In addition, since the alpha particles have low permeability, efforts are needed to make the sample thin enough to allow the alpha particles to escape sufficiently. This requires pretreatment such as electrodeposition after acid decomposition of the sample.
Thus, according to the conventional method, it is not easy to measure all the energy of particles generated when one nucleus collapses with a desired accuracy, and there is a problem that a pretreatment process is required.
On the other hand, the Q-spectroscopic technique using the low-temperature detector described above has a high resolution of energy spectrum and does not require a pre-processing step.
Accordingly, the inventors of the present invention have found that, by replacing the measurement of alpha particles due to alpha decay in the Q-spectroscopic technique using a low-temperature detector by measuring the fission products by neutron fission, the sensitivity and the signal- The present inventors have found that measurement of a smaller amount of nuclear material can be performed more easily and quickly, thus completing the present invention.
An object of the present invention is to provide a method of measuring a nuclear material using a neutron-assisted fission reaction and a low-temperature detector, and a device used therefor.
To this end,
Irradiating the sample with a neutron (step 1);
Obtaining a temperature signal according to a temperature change due to a fission reaction due to neutron irradiation in the step 1 (step 2); And
Measuring the rate of occurrence of the fission reaction from the temperature signal of step 2 and discriminating the nuclear material (step 3);
And a nuclear material measurement method using a low temperature detector.
In addition,
A foil foil filled with a sample;
A low temperature detector attached to one surface of the foil foil;
Amplifying means for amplifying a signal detected from the low temperature detector;
A chamber for receiving the gold foil, the low-temperature detector and the amplifying means therein to form a closed system; And
A neutron source for discharging neutrons into the chamber;
And a nuclear material measurement device using the neutron-induced fission reaction and the low-temperature detector.
According to the present invention, the measurement of alpha particles following alpha decay in the Q-spectroscopic technique using a low-temperature detector can be replaced by measuring the fission products resulting from neutron fission, thereby improving the sensitivity of the measurement and the signal- The measurement of positive nuclear material can be performed more easily and quickly. Unlike the case of using a conventional thermal ionization mass spectrometer, it can be performed without any special pretreatment process. This can be used for nuclear activity detection, illegal trading of nuclear materials and terrorism, environmental monitoring of high-level radioactive waste repository, monitoring of pollution in nuclear material processing facilities (nuclear fuel processing and production facilities), uranium measurement in the environment, Measurement and fission product research.
FIG. 1 (a) is a conceptual view of the technique using alpha spectroscopy; (b) is a conceptual diagram of a Q-spectroscopic technique using a low-temperature detector;
FIG. 2 is a conceptual diagram of a nuclear material measurement method using a neutron-assisted fission reaction and a low-temperature detector according to the present invention;
FIG. 3 is a table showing the state of neutron flux according to a neutron beam facility;
4 is a conceptual diagram of a measurement system configuration in the case of using the superconducting phase transition sensor according to the present invention.
An object of the present invention is to provide a method of measuring a nuclear material using a neutron-assisted fission reaction and a low-temperature detector, and a device used therefor. For this purpose, the present invention is based on the fact that in the Q-spectroscopic technique using a low-temperature detector, the measurement of alpha particles following alpha decay is replaced with the measurement of fission products following neutron fission, thereby improving the sensitivity of measurement and the signal- It provides a method of measuring nuclear material that can more easily and quickly measure positive nuclear material.
Therefore,
Irradiating the sample with a neutron (step 1);
Obtaining a temperature signal according to a temperature change due to a fission reaction due to neutron irradiation in the step 1 (step 2); And
Measuring the rate of occurrence of the fission reaction from the temperature signal of step 2 and discriminating the nuclear material (step 3);
And a nuclear material measurement method using a low temperature detector.
In the nuclear material measurement method according to the present invention, the step 1 is a step of irradiating a sample with neutrons.
In the method according to the present invention, by using a method of measuring the temperature change due to the kinetic energy of the fission products by adding a fission step through neutron irradiation instead of the conventional method of measuring alpha particles by alpha decay, As in the case of Q-spectroscopy by collapse, the preprocessing process of the sample is not required, and the signal to noise ratio (S / N ratio) is improved more than the energy in the conventional method.
Specifically, the nuclear material (U, etc.) releases neutrons, gamma rays, beta rays, neutrinos, and the like together while breaking into two or three nuclei (fission products) through a fission reaction with a neutron. Fissile reactions Like radioactive decay, there is a loss in the mass sum of all particles involved in the reaction before and after the reaction, which is called the Q-value of the fission reaction. The Q-value of the fission reaction is also distributed to the kinetic energy and photon energy of individual particles such as fission products, neutrons, etc., obtained by fission generation. Unlike the decay of radionuclides, the fission reaction does not have a single value for the Q-value of the fission reaction, but has a unique distribution. Since the Q-value of the fission reaction has a unique distribution, it is possible to determine the nuclear material that caused the fission reaction by measuring all the energy sum generated in the fission process. The Q-value of the fission reaction is about 200 MeV. The Q-value of the fission reaction is about 200 MeV, about 160 MeV being released as the kinetic energy of the fission product. Since the fission products are very low in transmittance (half of the 5 MeV alpha particles) their kinetic energy is absorbed by all of the gold foil absorbers.
The remainder of the Q-value of the fission reaction (about 40 MeV) is released as the kinetic energy of neutrons, gamma rays, beta rays and neutrinos. These particles have very high permeability and therefore have little energy transfer to the gold foil absorber.
Since the Q-value of the alpha particle is about 5 MeV but the Q-value of the fission product is about 160 MeV, according to the present invention, a signal 30 times stronger than that of the alpha particle can be obtained. Method is used, the signal to noise ratio is large, so that the measurement sensitivity is better.
These measurement methods can be used for nuclear activity detection, illegal trading of nuclear material and terrorism, environmental monitoring of high level radioactive waste repository, monitoring of pollution of nuclear material processing facility (nuclear fuel processing and production facility), uranium measurement in the environment, Can be used for fission cross-sectional area measurement and fission product research.
In the method of measuring nuclear material according to the present invention, it is preferable that the sample is enclosed with a foil foil. This is to allow the kinetic energy of the fission product released from the inside of the foil foil to be completely absorbed into the foil foil and converted to a temperature signal. Various methods can be used for sealing, but they can be sealed by a diffusion welding method, which is a technique of pressing and sealing the object with a roller while applying heat.
In the method of measuring nuclear material according to the present invention, it is preferable that the thickness of the foil foil is 15 mu m to 40 mu m. When the thickness of the foil foil is less than 15 탆, a part of the fission products is drained to the outside of the foil foil. Therefore, there is a problem in that it is impossible to measure an accurate fission reaction rate. When the thickness exceeds 40 탆, Therefore, there is a problem that the resolution of measured energy may be lowered.
In the nuclear measurement process according to the invention, the neutron irradiation in the step 1 10 6 cm -2 s - is preferably performed by irradiating the thermal neutrons or cold neutron beam of 1 to 10 9 cm -2 s -1 . The sensitivity of the device according to the invention depends on the intensity of the neutron beam. 3 is to represent the neutron flux at each institution neutron beam facility, and thus research reactors, from about 10 6 cm -2 s - used mainly neutrons lay apparatus of Fig. The neutron source is less than 10 6 cm -2 s -1, and the problem that the sensitivity is lowered when irradiating a neutron beam, neutron trick obtain thermal neutron or cold neutron beam exceeding 10 9 cm -2 s -1 is It is realistically difficult.
In the nuclear material measuring method according to the present invention, the step 2 is a step of obtaining a temperature signal according to a temperature change from the neutron irradiated sample in the step 1. Since the sample is completely enclosed within the foil foil, the kinetic energy of the fission product can be absorbed into the foil foil altogether. This results in a temperature change on the foil foil, which can be detected by a low-temperature detector with excellent energy resolution.
In the method of measuring a nuclear material according to the present invention, the temperature signal of the step 2 may include a transition edge sensor (TES), a metalic magnetic calorimeter (MMC) and a superconduction tunnel junction (STJ) Is preferably obtained through one kind selected from the group consisting of
The TES (Transition Edge Sensor) is a calorimeter that uses a high sensitivity characteristic of a SQUID (Superconducting Quantum Interference Device) and a phenomenon in which electrical resistance of a superconductor rapidly changes near a metal and a superconducting transition temperature (see FIG. 4). As the gold foil absorbs the energy generated by fission through neutron irradiation and the resistance increases in the sensor, a current change proportional to the absorbed energy occurs in the circuit. By measuring the change of the minute current with the SQUID, it is possible to precisely measure the generated energy and analyze the energy spectrum.
The MMC (metalic magnetic calorimeter) absorbs energy generated by fission through neutron irradiation from the foil foil, and when the temperature rises, the magnetic susceptibility of the sensor changes, and the change is measured by the SQUID .
The superconducting tunnel junction (STJ) utilizes the tunneling phenomenon depending on the thickness of the barrier in the superconducting-insulator-metal junction. When the superconducting tunnel junction is used, energy generated by fission through neutron irradiation The foil absorbs and current is generated at the junction due to the temperature change. By measuring the change of the minute current with the SQUID, it is possible to precisely measure the generated energy and analyze the energy spectrum.
In the nuclear material measurement method according to the present invention, the
In the nuclear material measurement method according to the present invention, it is preferable that the
In addition,
A foil foil filled with a sample;
A low temperature detector attached to one surface of the foil foil;
Amplifying means for amplifying a signal detected from the low temperature detector;
A chamber for receiving the gold foil, the low-temperature detector and the amplifying means therein to form a closed system; And
A neutron source for discharging neutrons into the chamber;
And a nuclear material measurement device using the neutron-induced fission reaction and the low-temperature detector.
In the nuclear material measuring apparatus according to the present invention, the present invention includes a foil foil in which a sample is enclosed. The foil foil is sealed in a double-layered form so as to surround the entire sample. This is to allow the kinetic energy of the fission product released from the inside of the foil foil to be completely absorbed into the foil foil and converted to a temperature signal. Various methods can be used for sealing, but they can be sealed by a diffusion welding method, which is a technique of pressing and sealing the object with a roller while applying heat.
Preferably, the gold foil foil is sealed so as to cover the entire sample with a thickness of 15 μm to 40 μm in order to prevent the fission products from escaping by wrapping the sample and to reduce the mass of the gold foil absorber to maximize possible temperature increase. When the thickness of the foil foil is less than 15 탆, a part of the fission products is discharged to the outside of the foil foil. Therefore, there is a problem that the rate of occurrence of fission can not be accurately measured. Therefore, there is a problem that the resolution of measured energy may be lowered.
In the nuclear material measuring apparatus according to the present invention, the present invention includes a low temperature detector attached to one surface of the foil foil. The low temperature detector may be one selected from the group consisting of a transition edge sensor (TES), a metalic magnetic calorimeter (MMC), and a superconduction tunnel junction (STJ).
The TES (Transition Edge Sensor) is a calorimeter that uses a high sensitivity characteristic of a SQUID (Superconducting Quantum Interference Device) and a phenomenon in which electrical resistance of a superconductor rapidly changes near a metal and a superconducting transition temperature (see FIG. 4). As the gold foil absorbs the energy generated by fission through neutron irradiation and the resistance increases in the sensor, a current change proportional to the absorbed energy occurs in the circuit. By measuring the change of the minute current with the SQUID, it is possible to precisely measure the generated energy and analyze the energy spectrum.
The MMC (metalic magnetic calorimeter) absorbs energy generated by fission through neutron irradiation from the foil foil, and when the temperature rises, the magnetic susceptibility of the sensor changes, and the change is measured by the SQUID .
The superconducting tunnel junction (STJ) utilizes the tunneling phenomenon depending on the thickness of the barrier in the superconducting-insulator-metal junction. When the superconducting tunnel junction is used, energy generated by fission through neutron irradiation The foil absorbs and current is generated at the junction due to the temperature change. By measuring the change of the minute current with the SQUID, it is possible to precisely measure the generated energy and analyze the energy spectrum.
In the nuclear material measuring apparatus according to the present invention, the present invention includes an amplifying means for amplifying a signal detected from the low temperature detector.
At this time, it is preferable that the amplifying means is a Superconducting Quantum Interference Device (SQIID) chip. Wherein the amplifying means amplifies a signal detected from the low temperature detector and outputs the amplified signal,
A SQUID sensor for detecting a signal from the low temperature detector;
A SQUID array for amplifying a signal detected from the SQUID sensor; And
Stage SQUID system including an FLL (Flux-locked loop) circuit for comparing and integrating the amplified signals.
The SQUID chip is a superconducting quantum interference device, and it can measure the magnetic field change very sensitively.
In the nuclear material measuring apparatus according to the present invention, the present invention includes a chamber for receiving the gold foil, the low temperature detector and the amplifying means to form a closed system. The chamber is a kind of low-temperature thermostat having a magnetic shielding function capable of utilizing superconducting property, low heat capacity or low thermal noise which can be obtained at a low temperature by keeping the internal temperature of a closed system at a very low temperature (generally 1 K or less). In addition, the chamber is provided with cooling means to cool the internal airtightness system. The chamber may be a dewar, and the cooling unit may be provided in the dewar.
In the nuclear material measurement apparatus according to the present invention, it is preferable that the chamber is maintained at a temperature of less than 1 K. The apparatus according to the present invention is for detecting a nuclear material through a temperature change caused by a kinetic energy of a fission material. As the temperature is lower, the thermal capacity is decreased and the signal to noise ratio (S / N ratio) . Therefore, it is preferable that the chamber including the gold leaf foil, the low temperature detector, and the SQUID is maintained at a cryogenic temperature of 1 K or less.
In the nuclear material measuring apparatus according to the present invention, it is preferable that the apparatus further includes a cooling means for maintaining a cryogenic temperature. According to the present invention, since fissure due to fission occurs in every measurement event, it can be re-cooled through the heat sink to the temperature before the event and then the next event can be performed.
In the nuclear material measuring apparatus according to the present invention, the present invention includes a neutron source for discharging a neutron to the chamber. The neutron source can use a reactor to irradiate the sample with a neutron beam.
Preferably, the neutron source is irradiated with a thermal neutron or a cold neutron beam of 10 6 cm -2 s -1 to 10 9 cm -2 s -1 onto the foil foil. The sensitivity of the device according to the invention depends on the intensity of the neutron beam. It is possible to obtain a neutron flux at 1 10 9 cm -2 s -1 range to Figure 3, each institution neutron beam represent the neutron flux at the facility, and thus by using the research reactor of about 10 6 cm -2 s. The neutron if the source is irradiated with a neutron beam of less than 10 6 cm -2 s -1, and a problem that the sensitivity of the measurement is lowered, 10 9 cm -2 s -1 or cold thermal neutrons a neutron beam that exceeds the gain is realistically There is a problem that it is difficult.
The nuclear material detection sensitivity according to the present invention when neutron beam facility of neutron flux of 10 < 8 & gt ; cm < -2 & gt ; s & lt; -1 is used exhibits an effect superior to sensitivity in Q-spectroscopy using a conventional low temperature detector. The effect according to the present invention can be confirmed by comparing the sensitivity in the Q-spectroscopy using the conventional low-temperature detector with the expected counting rate per second in the nuclear material detection sensitivity according to the present invention.
Hereinafter, a method of measuring the counting rate per second will be described in detail.
The sensitivity calculation method in Q-spectroscopy using a conventional low-temperature detector is as follows. When the sample is measured for a time of t (s) with a detector having an efficiency of?, N a The number of times of alpha collapse can be obtained.
&Quot; (1) "
In Equation (1), A is a radioactivity (decay rate per hour) of an alpha-decaying isotope (nuclear material), and can be obtained by the following equation (2).
&Quot; (2) "
In Equation 2, T 1/2 (s ) is the half-life of the isotope (nuclear material), n is the number of the radioisotope (nuclear material).
Generally, Q-spectroscopy using a low-temperature detector uses a gold foil absorber encircling the entire sample in a sandwich form, so that all particles emitted in all directions (4?) Are detected, so that? The half-life of each nuclear material is shown in Table 1 below.
The sensitivity calculation method in the measuring method according to the present invention is as follows. When the sample is measured for a time t (s) with a detector having an efficiency of?, Nf The number of fission events can be obtained.
&Quot; (3) "
In the above equation (3), F is the fission generation rate and can be obtained by the following equation (4).
&Quot; (4) "
In Equation (4), n is the number of the corresponding nuclear material (isotope), and? Th (cm -2 · s -1 ) is the thermal neutron flux (flux), and σ f (cm 2 ) is the fission cross section for the thermal neutron.
In the present invention, since a nuclear material is detected in all directions (4 pi) because a gold leaf foil absorber encircling the entirety of the sample is used in sandwich form, ε in Equation (3) corresponds to 100%. The cross-sectional area (σ f ) of the neutron fission neutrons for each nuclear material is shown in Table 2 below. At this time, The unit [b] of σ f corresponds to 1 b = 1 × 10 -24 cm 2 , the unit commonly used when describing the nuclear reaction cross-section.
(? f ),
Unit: b
585.081
2807.93
94.744
The counting rate per second (s -1 ) for each nuclear material was calculated by the above methods. The counting rate per second is the degree to which the unit detector perceives particles of nuclear material per unit time, indicating the measurement sensitivity.
Conventional Q-spectroscopy and the counting rate per mg of the sample according to the present invention were calculated using the method described above, and the results are shown in Table 3 below. At this time, the counting rate according to the present invention was obtained in the case of irradiating a thermal neutron beam of 1 × 10 8 cm -2 · s -1 .
Q-spectroscopy
(Unit: counts / s / mg)
80
2400
3400
Invention
(Unit: counts / s / mg)
1.5 × 10 5
7.2 x 10 5
2.3 x 10 4
As shown in Table 3, using the neutron-assisted fission reaction and the method for measuring nuclear material using a low-temperature detector according to the present invention, the measurement sensitivity is significantly increased as compared with the conventional nuclear material measurement method using Q-spectroscopy Can be confirmed.
This is because the method according to the present invention uses a method of measuring the temperature change due to the kinetic energy of the fission product by adding a fission step through neutron irradiation instead of the conventional measurement of alpha particles by alpha decay, The signal-to-noise ratio (S / N ratio) and the sensitivity are improved. Specifically, when a nuclear material generates fission, it is split into two or three nuclei having high kinetic energy, and a fission product is formed. Since the energy of the alpha particle is about 5 MeV on the average but the energy of the fission product is about 160 MeV, according to the present invention, a signal 30 times stronger than that of the alpha particle can be obtained. It can be seen that the measurement sensitivity is further improved.
Also, in the method of measuring the nuclear material using the neutron-assisted fission reaction and the low temperature detector according to the present invention, the sample amount m req , f for obtaining the nuclear material detection result in the range of the relative standard deviation of 0.1% The effect of the method for measuring nuclear material according to the present invention can be confirmed by comparing the amount of sample m req , Q for obtaining the nuclear material detection result in the range of the standard deviation of 0.1%.
Hereinafter, a method of measuring the expected sample amount will be described in detail.
Since radioactive decay or nuclear reactions are unlikely to occur, statistics of related measurements are known to follow Poison statistics. Therefore, when the coefficient of the event to be measured is N, the standard deviation (SD) and the relative standard deviation (RSD) of the measurement can be obtained by the following equations (5) and (6).
&Quot; (5) "
&Quot; (6) "
The coefficient N needed to obtain the result of the relative standard deviation of 0.1% by the above equation (5) is 1 × 10 6 .
Therefore, in the Q-spectroscopy using the conventional low-temperature detector, the amount of sample m req , Q (㎍) required to obtain the result of relative standard deviation of 0.1% is calculated as shown in Equation (7).
&Quot; (7) "
In Equation 7, T 1/2 (s ) is the half-life, t (s) is the measured time, m is a atomic mass (g / mol), N A is (mol -1) Avogadro's number of the nuclear material . At this time, the atomic weight of each nuclear material is shown in Table 4, and the half-life period of each nuclear material is shown in Table 1 above.
(Unit: g / mol)
235.0439
236.0465
247.0703
In the method of measuring the nuclear material using the neutron-assisted fission reaction and the low temperature detector according to the present invention, the amount of sample m req , f (㎍) necessary for obtaining the nuclear material detection result in the range of relative standard deviation of 0.1% .
&Quot; (8) "
In Equation (8),? Th (cm -2 s -1 ) is the thermal neutron flux, σ f (cm 2 ) is the fission cross section for the thermal neutron, t (s) is the measurement time, m a is the atomic weight (g / mol) , And N A is the number of Avogadro's (mol -1 ). At this time, the atomic weight of each nuclear material is as shown in Table 4, and the cross-sectional area of fission for thermal neutron is as shown in Table 2 above.
The expected sample requirements to obtain nuclear material detection results were calculated through the above methods in the range of relative standard deviation of 0.1%. At this time, when the measurement time t is increased in Equations (7) and (8), it can be seen that the amount of sample required to obtain the result of relative standard deviation (RSD) of 0.1% decreases. However, it takes a long time to measure, which increases the cost. Therefore, the expected sample requirement for obtaining the measurement result with the relative standard deviation (RSD) of 0.1% is presented in Table 5 when the measurement time is 2 hours. Further, in the method according to the present invention, the expected sample amount was calculated in the case of irradiating a thermal neutron beam of 1 × 10 8 cm -2 · s -1 .
(Unit: ㎍)
1700
60
40
(Unit: ㎍)
0.9
0.2
6
As shown in Table 5, using the neutron-assisted fission reaction and the nuclear material measurement method using a low-temperature detector according to the present invention, the relative standard deviation of 0.1% The expected sample requirement for obtaining the nuclear material detection result is remarkably reduced.
This is because the method according to the present invention uses a method of measuring the temperature change due to the kinetic energy of the fission products by introducing the fission step through the neutron irradiation instead of the conventional measurement of alpha particles by alpha decay, The signal to noise ratio (S / N ratio) and the signal to noise ratio are improved. Specifically, when a nuclear material generates fission, it is split into two or three nuclei having high kinetic energy, and a fission product is formed. Since the energy of the alpha particle is about 5 MeV but the energy of the fission product is about 160 MeV, a signal 30 times stronger than the alpha particle can be obtained according to the present invention.
Accordingly, it can be seen that according to the present invention, a nuclear material can be detected using a significantly smaller amount of sample than in the case of using the method according to the conventional Q-spectroscopy.
Claims (14)
Obtaining a temperature signal according to a temperature change due to a fission reaction due to neutron irradiation in the step 1 (step 2); And
Measuring the rate of occurrence of the fission reaction from the temperature signal of step 2 and discriminating the nuclear material (step 3);
And a nuclear material measurement method using a low temperature detector.
Wherein the sample is enclosed with a foil foil so that the entire sample is enclosed by the foil.
Wherein the thickness of the foil foil is from 15 占 퐉 to 40 占 퐉. A method of measuring nuclear material using a neutron-assisted fission reaction and a low-temperature detector.
The temperature signal of step 2 is obtained through one kind selected from the group consisting of a superconducting tunnel junction (STJ), a transition edge sensor (TES), a metalic magnetic calorimeter (MMC) And a method of measuring a nuclear material using a low temperature detector.
Wherein the neutron irradiation in step 1 is performed by irradiating a thermal neutron or a cold neutron beam having a wavelength of 10 6 cm -2 s -1 to 10 9 cm -2 s -1 . Method of measuring nuclear material.
Wherein the step 3 counts the pulse of the temperature signal according to the temperature change to measure the rate of occurrence of the fission reaction, and discriminates the nuclides through the magnitude of each pulse. The nuclear fission reaction by the neutron and the nuclear material measurement using the low temperature detector Way.
A low temperature detector attached to one surface of the foil foil;
Amplifying means for amplifying a signal detected from the low temperature detector;
A chamber for receiving the gold foil, the low-temperature detector and the amplifying means therein to form a closed system; And
A neutron source for discharging neutrons into the chamber;
And a neutron-induced fission reaction and a low-temperature detector.
Wherein the thickness of the gold foil foil is 15 占 퐉 to 40 占 퐉 to enclose the entire specimen. The apparatus for measuring nuclear material using a neutron-assisted fission reaction and a low temperature detector.
Wherein the low temperature detector is one selected from the group consisting of a transition edge sensor (TES), a metalic magnetic calorimeter (MMC), and a superconduction tunnel junction (STJ) And a nuclear material measuring device using a low temperature detector.
Wherein the neutron source irradiates the gold foil with a thermal neutron or a cold neutron beam having a density of 10 7 to 10 9 cm -2 s -1 and a nuclear material reaction using the neutron and a low temperature detector.
Wherein the amplifying means is a Superconductini quantum interference device (SQIID) chip.
The Superconductini quantum interference device (SQUID)
A SQUID sensor for detecting a signal from the low temperature detector;
A SQUID array for amplifying a signal detected from the SQUID sensor; And
Stage SQUID system including an FLL circuit for comparing and integrating the amplified signals. The apparatus for measuring nuclear material using a neutron-assisted fission reaction and low-temperature detector.
Wherein the chamber is maintained at a temperature of less than 1 K. The apparatus for measuring nuclear material using a neutron-assisted fission reaction and low temperature detector.
Wherein the apparatus further comprises a cooling means for maintaining the cryogenic temperature. The apparatus for measuring nuclear material using a neutron-assisted fission reaction and a low temperature detector.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020120128795A KR20140062292A (en) | 2012-11-14 | 2012-11-14 | The measuring method of nuclear material by nuclear fission reaction by neutron and low temperature detector, and the device thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020120128795A KR20140062292A (en) | 2012-11-14 | 2012-11-14 | The measuring method of nuclear material by nuclear fission reaction by neutron and low temperature detector, and the device thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| KR20140062292A true KR20140062292A (en) | 2014-05-23 |
Family
ID=50890600
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| KR1020120128795A KR20140062292A (en) | 2012-11-14 | 2012-11-14 | The measuring method of nuclear material by nuclear fission reaction by neutron and low temperature detector, and the device thereof |
Country Status (1)
| Country | Link |
|---|---|
| KR (1) | KR20140062292A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111627581A (en) * | 2020-06-09 | 2020-09-04 | 中国原子能科学研究院 | Method and device for measuring fast reactor power distribution |
| CN115390127A (en) * | 2022-08-31 | 2022-11-25 | 西北核技术研究所 | Fast neutron flux high signal-to-noise ratio monitoring method and system |
-
2012
- 2012-11-14 KR KR1020120128795A patent/KR20140062292A/en not_active Application Discontinuation
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111627581A (en) * | 2020-06-09 | 2020-09-04 | 中国原子能科学研究院 | Method and device for measuring fast reactor power distribution |
| CN111627581B (en) * | 2020-06-09 | 2022-06-28 | 中国原子能科学研究院 | Method and device for measuring fast reactor power distribution |
| CN115390127A (en) * | 2022-08-31 | 2022-11-25 | 西北核技术研究所 | Fast neutron flux high signal-to-noise ratio monitoring method and system |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Guerrero et al. | The n_TOF Total Absorption Calorimeter for neutron capture measurements at CERN | |
| Konijn et al. | A high resolution, large volume Ge (Li) NaI (Tl) compton-suppression spectrometer | |
| Lindstrom et al. | Activation analysis opportunities using cold neutron beams | |
| Simon et al. | Feasibility study of fissile mass quantification by photofission delayed gamma rays in radioactive waste packages using MCNPX | |
| Tobin et al. | Nondestructive assay options for spent fuel encapsulation | |
| Steinhauser et al. | Gas ionization detectors | |
| Ryzhikov et al. | Advanced multilayer composite heavy-oxide scintillator detectors for high-efficiency fast neutron detection | |
| KR20140062292A (en) | The measuring method of nuclear material by nuclear fission reaction by neutron and low temperature detector, and the device thereof | |
| Hirose et al. | Simultaneous measurement of neutron-induced fission and capture cross sections for 241Am at neutron energies below fission threshold | |
| Biswas et al. | Facility at CIRUS reactor for thermal neutron induced prompt γ-ray spectroscopic studies | |
| Carasco et al. | Photofission delayed gamma-ray measurements in a large cemented radioactive waste drum during LINAC irradiation | |
| Islam et al. | Study of a laboratory-based gamma spectrometry for food and environmental samples | |
| Anders | Neutron-activation sensitivities | |
| Nicol et al. | 235U and 239Pu characterization in radioactive waste using neutron-induced fission delayed gamma rays | |
| Naydenov et al. | Advanced multilayer composite structures for fast neutron detection and shielding protection applications | |
| Koizumi et al. | LaBr3 γ-ray spectrometer for detecting 10B in debris of melted nuclear fuel | |
| Jiahui et al. | Energy calibration of organic scintillation detectors for. gamma. rays | |
| Peerani et al. | Non-Destructive Assay for Nuclear Safeguards | |
| Ghosh et al. | A feasibility study exploring the use of high-pressure xenon (HPXe) detectors for the characterization of spent fuel bundles | |
| Gao et al. | Design of a compact detector for nuclear-fuel-rod enrichment detection | |
| Jin et al. | Application of In-beam Activation Analysis in Elemental Distribution Analysis | |
| Vuong et al. | Neutron capture cross section measurements of 109 Ag, 186 W and 158 Gd on filtered neutron beams of 55 and 144 keV | |
| Tsuchiya et al. | Performance of large volume LaBr3 scintillation detector equipped with specially-designed shield for neutron resonance capture analysis | |
| ZAVED | STUDY ON EXPERIMENTAL CROSS SECTIONS FOR REACTIONS 174Yb (n, γ) 175Yb AND 55Mn (n, γ) 56Mn AT NEW ENERGIES OF 0.0334 AND 0.0536 eV USING NEUTRONS FROM TRIGA NUCLEAR REACTOR | |
| Wu et al. | Experimental Methods of Fusion Neutronics |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A201 | Request for examination | ||
| E902 | Notification of reason for refusal | ||
| E601 | Decision to refuse application | ||
| WITB | Written withdrawal of application |