KR20150080811A - BF3 neutron detection system with self-diagnosis function, and its method - Google Patents

Abstract

The present invention relates to a BF3 neutron measurement system and a method thereof and, more specifically, to a BF3 neutron measurement system, including a function of diagnosing the malfunction of a measurement device and a sensitivity change of a neutron measurement system, and a method thereof. The measurement system, capable of detecting a neutron by using BF3 charging gas, includes a multichannel analyzer (110) for obtaining a signal detected by a BF3 detector; an analyzing module (120) storing reference distribution sampled by using the number as a reference count according to neutron energy from the signal obtained by the multichannel analyzer (110), and diagnosing and analyzing the soundness of the system based on a relationship between the reference distribution and measurement distribution; an input part (130) inputting variable information into the analyzing module (120); and an output module (140) outputting a diagnosis and analysis result of the analyzing module.

Description

[0001] The present invention relates to a BF3 neutron detection system having a self-diagnostic function,

The present invention relates to a BF3 neutron measurement system and a method thereof, and more particularly, to a measurement system and a measurement method having a function of self-diagnosing a change in sensitivity of a neutron measurement system and a failure of the measurement equipment.

Since neutrons do not directly atomize atoms, the detection of neutrons is an indirect process that detects secondary events in reactions such as (n, p), (n, Detection methods should be applied.

Particularly, the (n, α) reaction of B-10 is used for the detection of thermal neutrons, and the electric energy generated by Li-7 and α particles is converted into a pulse signal.

B-10 (19.8%) and B-11 (80.2%) exist in the natural core of boron (B), and B-10 has a large cross- %), It is possible to increase the measurement efficiency of the neutron.

The main reaction of BF3 gas used for the detection of thermal neutrons is as follows.

FIG. 1 is a diagram showing the measurement principle of a gas type BF3 neutron detector including a general ionizer. In the reaction between B-10 and a neutron, ions in an ionization chamber are ionized to generate ion pairs of electrons and positive ions. The positive high voltage moves to the anode, the positive ions move to the cathode, the current is collected by each electrode, and the pulse counter measures the number of neutrons by measuring the pulse generated in the pulse counter circuit. The cathode of the detector is generally made of aluminum having a small neutron sectional area, and the anode has a thin wire shape.

FIG. 2 is a diagram showing a general BF3 neutron measurement system. FIG.

The BF3 neutron measurement system amplifies the signal detected by the BF3 detector 10 and selects only a voltage pulse of a predetermined magnitude from a pulse height discriminator 20 to convert it into a constant waveform. A pulse shaper 30 and a pulse divider 40 for converting the pulse signal into a low frequency pulse string to output a signal output through a log pulse integrator 50 Neutron measurement signal.

However, since such a conventional neutron measurement system acquires only the number of pulses detected by the detector, it is impossible to know the failure of the detector or the measurement system and the decrease of the neutron sensitivity. Therefore, as in the nuclear power plant, There is a problem that the maintenance of the integrity of the detector or the measurement system can not be relied upon.

Japanese Patent Application Laid-Open No. 10-2011-0034576 (published on April 04, 2011)

Patent Registration No. 10-1282962 (Registration date: 2013.07.01)

An object of the present invention is to provide a measurement system having a function of self-diagnosing a soundness by using a reference distribution which can be used as an axiomatic reference to a change in sensitivity of a neutron measurement system and a failure of the measurement equipment And to provide a method thereof.

In order to achieve the above object, a BF3 neutron measuring system having a self-diagnosis function of the present invention is a neutron measuring system for detecting neutrons using a BF3 filling gas, A channel analyzer; An analyzing module for analyzing the soundness of the system from the relationship between the reference distribution and the measurement distribution, wherein the reference distribution is sampled by using the number of neutron energies as a reference coefficient from the signal acquired from the multi-channel analyzer; An input unit for inputting variable information to the analysis module; And an output unit for outputting a diagnostic analysis result of the analysis module.

Preferably, in the present invention, the reference distribution is characterized in that the total number of neutrons used in the same measurement as the reference coefficient is expressed by a linear relationship with a measurement distribution having the same measurement coefficient.

Preferably, in the present invention, the variable information includes at least one standard deviation and a diagnostic condition.

The BF3 neutron measurement method having the self-diagnosis function of the present invention is a neutron measurement method for detecting neutrons using a BF3-filled gas. The neutron measurement method includes the steps of: And stores the reference distribution and diagnoses and analyzes the health of the system from the relationship between the reference distribution and the measurement distribution.

The BF3 neutron measurement system and the method having the self-diagnosis function according to the present invention have an advantage that the sensitivity change and failure of the neutron measurement system can be self-diagnosed at a certain time.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram showing the principle of measurement of a general gas type BF3 neutron detector,
2 is a diagram illustrating a general BF3 neutron measurement system,
3 (a) and 3 (b) schematically show the (n, α) reaction of B-10,
4 (a) and 4 (b) schematically show the (n, a) reaction of B-10 in consideration of the side wall effect of the detector,
Figure 5 is a graph showing the pulse height spectrum of the BF3 detector,
FIG. 6 is a graph showing a reference distribution showing the pulse height and the number of neutrons obtained by using a multi-channel analyzer for the BF3 detector used in the nuclear reactor core charging in the nuclear reactor,
Figure 7 is a graph showing the relationship between a reference distribution and a measurement distribution,
8 is a block diagram of a BF3 neutron measurement system according to the present invention.
9 is a flow chart showing a BF3 neutron measurement method according to the present invention,
FIG. 10 is a graph illustrating an example of a criterion using the BF3 neutron measurement system according to the present invention,
11 is a graph showing an example of self-diagnosis using a BF3 neutron measurement system according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout thefigures, The present invention is not limited to these embodiments.

The self-diagnosis function of the present invention is based on the following axiomatic basis when there is no failure of the measurement system.

The BF3 detector always has a specific spectrum, regardless of the incident neutron energy.

이내에 존재해야 한다.- The spectrum of the BF3 detector has the same shape. The measurement uncertainty due to the difference in number is theoretically

.

- the spectra of the BF3 detector obtained from statistically sufficient neutron numbers for the same detector and the distribution of the spectra obtained from the neutron number (n) on the same graph, if the detector is sound even though it has an uncertainty according to the number of measurements It should be linear (y = ax; a is a constant).

The present invention is based on the above-mentioned axiomatic criteria, and the linearity is checked through a statistical comparison between the reference spectrum and the measurement spectrum, which have been measured and calculated in advance, to determine whether the measurement system itself has failed or the sensitivity and soundness of the measurement equipment. .

The distribution of the reference spectrum can be used as an axiomatic reference because the measurement system must always have a uniform distribution in the case of soundness. In the statistical sense, the distribution of the population does not change, It is like you know. Thus, since the reference spectrum can be used as a statistically invariant criterion, the reference spectrum can be used as a reference distribution for comparing and analyzing the lateral spectra during neutron measurements. For example, the reference spectrum can be used by acquiring at least 1 million incident neutrons to become a population with sufficient statistical significance using a neutron source.

On the other hand, the abnormality of the measurement system is judged by analyzing the linearity between the reference spectrum (population) and the measurement spectrum (sample group). After the measurement spectrum is statistically processed in units of a certain cumulative number of neutrons, Calculate the measurement uncertainty of the analysis and sample. Finally, after neutron measurement is completed, all measured neutrons can be statistically processed to determine whether the measurement system is malfunctioning or to justify the measurement.

Figs. 3 (a) and 3 (b) are diagrams showing the (n, a) reaction of B-10 and show the base state and excitation state, respectively.

In BF3 gas, B-10 is generated in Li-7 and α particles and then moves in the opposite direction, while the magnitude of the detected pulse is in the excited state (94%) and grounded state (6%), and the energy of α particle is about 1.78 MeV for 6% and 1.47 MeV for 94%.

When the diameter of the detector is large, all kinetic energy of the alpha particle and Li-7 is transferred to the detection gas, and thus a large peak is generated at 2.31 MeV (excited Li-7) in the pulse height spectrum and 2.79 MeV Of Li-7), two peaks may appear.

On the other hand, in the case of a tube with a typical size of 2-5 ㎝ in diameter, small peaks other than 2.31 MeV and 2.79 MeV may appear. This is because the kinetic energy of α particles and Li-7 is not transferred to the detection gas, And transmitted.

4 (a) and 4 (b) are diagrams schematically showing the (n, a) reaction of B-10 in consideration of the sidewall effect of the detector.

As shown in FIG. 4 (a), in the (n, α) reaction of B-10, α particles collide with the sidewalls and only some energy is transferred, while all of the kinetic energy of Li- Peaks may occur in MeV.

Next, as shown in FIG. 4 (b), when Li-7 collides with the sidewall, only a part of the kinetic energy of Li-7 is transferred, while all the kinetic energy of the α- A peak may be generated.

FIG. 5 is a graph showing the pulse height spectrum of the BF3 detector. In the BF3 detector, a distribution graph showing constant characteristics regardless of the energy of incident neutrons can be confirmed. In fact, it is difficult to distinguish between 0.84 MeV and 1.47 MeV peaks .

Such a characteristic graph is related to the geometry of the detector and is independent of the energy of the neutron incident. Therefore, the detector count rate is important information, and the pulse height may vary slightly depending on the geometry of the detector.

Therefore, if the number of neutrons is measured by a multichannel analyzer according to the neutron energy through sampling of a sufficient number (for example, one million or more) of neutron sources after the BF3 detector is manufactured, the distribution shown in FIG. 6 is obtained .

FIG. 6 is a graph showing a reference distribution showing the pulse height and the number of neutrons using a multi-channel analyzer for the BF3 detector used in the nuclear reactor initial core fuel loading.

Figure 7 is a graph showing the relationship between the reference distribution and the measurement distribution.

As shown in FIG. 7, the relationship between the reference distribution and the measured distribution is as follows. The number of neutron energies from the signal obtained from the multi-channel analyzer is represented as a reference count on the x-axis, If the measurement distribution with the same number of measured neutrons used in the same measurement as the coefficient is plotted on the y-axis, the same BF3 detector from the axiom perspective can be used to determine the neutron count It can be seen that there is a linear relationship when there is no failure of the detector.

Therefore, in the present invention, the health of the system can be diagnosed by using the relational expression between the reference distribution and the measurement distribution detected by the BF3 detector.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same elements as those of the conventional art are denoted by the same reference numerals and duplicate descriptions are omitted.

8, the BF3 neutron measurement system of the present invention comprises a multi-channel analyzer 110 for acquiring a signal detected and amplified by the BF3 detector 10, An input module 130 for inputting information to the analysis module 120, and an output module 130 for outputting a diagnostic analysis result. The analysis module 120 analyzes the integrity of the system, (140).

As illustrated in FIG. 9, the analysis module 120 may include detecting a neutron through a BF3 detector (S10) and using the number of neutron energies as a reference coefficient using the signal obtained from the multi-channel analyzer 110 Measuring and storing a reference distribution, wherein the reference distribution can be expressed as x = y by displaying the same number of measured values on the x-axis and the y-axis respectively on the xy-axis graph, , And this slope value (x = y) is a reference slope of the soundness judgment of the system in the relation of the measurement distribution and the reference distribution (slope).

In the next step S30, a reference equation is calculated with respect to the measured coefficient value. At this time, the input variable is input through the input device. The input variable includes the standard deviation sigma or the total number n of measurement neutrons, The threshold value LLD and the upper threshold value ULD may be input.

의 합으로 구할 수가 있다.For example, the measurement reference line (Y_i (E)) is the measurement value (x_i (E)) and

. ≪ / RTI >

In the next step S40, whether or not the measurement reference line is within the range of the standard deviation from the reference distribution is counted for each of Count_in which is within the standard deviation range (Count_in) and Count_out which is outside the standard deviation range (S41) (S42).

In the next step S50, the defect rate (Count_out / Count_in) is calculated, and the diagnostic result of the system is outputted according to the defect rate value.

For example, if the calculated defective rate is compared with the diagnostic condition (constraint), it is judged to be normal if it is within a certain range, and if it is more than a certain range, it is judged to be faulty.

As illustrated in FIG. 10, the width a around the reference distribution is the area calculated by the lower threshold value (LLD), the width b represents the area calculated by the upper threshold value (ULD), and the two diagnostic conditions It is possible to determine the presence or absence of a failure.

For example, when the defect rate is < a, it is determined as a normal state, and when it is < b, it is determined as a caution state, and when it is > b, it can be judged as a failure state.

On the other hand, when the same neutron instrument is acquired at the same position, it can be deduced that the neutron source strength decreases or the neutron meter sensitivity decreases when the slope decreases.

11 is a graph showing an example of self-diagnosis using the BF3 neutron measurement system according to the present invention. It is determined whether the measured coefficient values are located in the range of the diagnostic condition (black line) around the reference distribution (black data) It is possible to determine whether or not the detection system is abnormal.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. It will be apparent to those of ordinary skill in the art.

10: BF3 detector 20: wave detector
30: pulse regulator 40: pulse divider
50: Pulse integrator 110: Multichannel analyzer
120: analysis module 130: input
140:

Claims (6)

A neutron measurement system for detecting a neutron using a BF3 charged gas,
A multi-channel analyzer for acquiring a signal detected by a BF3 detector;
An analyzing module for analyzing the soundness of the system from the relationship between the reference distribution and the measurement distribution, wherein the reference distribution is sampled by using the number of neutron energies as a reference coefficient from the signal acquired from the multi-channel analyzer;
An input unit for inputting variable information to the analysis module;
And an output unit for outputting a diagnostic analysis result of the analysis module. The system of claim 1, wherein the reference distribution is represented by a linear relationship with a measurement distribution having the same total number of neutrons used in the same measurement as the reference coefficient. 2. The BF3 neutron measurement system of claim 1, wherein the variable information has a self-diagnostic function including at least one standard deviation and a diagnostic condition. A neutron measurement method for detecting neutrons using a BF3 packed gas,
Wherein a sampled reference distribution is stored with reference to the number of neutron energies from the signal detected by the BF3 detector, and the integrity of the system is diagnosed and analyzed from the relationship between the reference distribution and the measurement distribution. BF3 Neutron measurement method. 5. The method of claim 4, wherein the reference distribution is represented by a linear relationship with a measurement distribution having the same total number of neutrons used in the same measurement as the reference coefficient. 6. The method of claim 5, further comprising the step of receiving an input variable that includes a standard deviation of the measurement coefficient and an uncertainty range that is a criterion for determining system integrity, as a diagnostic condition.

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