KR101975986B1 - Radioactivity measuring device and method for detecting radioactivity using the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radioactivity measuring apparatus and a radioactivity detecting method using the same, and more particularly, to a radioactivity measuring apparatus and a radioactivity detecting method using the same, Response.

Description

TECHNICAL FIELD [0001] The present invention relates to a radioactivity measuring apparatus and a radioactivity measuring apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radioactivity measuring apparatus and a radioactivity detecting method using the same, and more particularly, to a radioactivity measuring apparatus and a radioactivity detecting method using the same, And a method using the same.

The contents described in this section merely provide background information on the present embodiment and do not constitute the prior art.

Recently, a lot of nuclear power plants are being built to cope with soaring energy demand. However, maintenance and management of such nuclear power plants require a lot of cost and technology, and there is always a risk that large-scale safety accidents may occur have.

A pressurized water reactor of a nuclear power plant cools the primary and secondary systems by closed circuit circulation to prevent radiation leakage. However, leakage accidents in the cooling system are increasing due to increased number of years of operation of the reactors, worker errors, fatigue of metal pipes and corrosion. In addition, such radiation accidents are linked to accidents where workers are exposed.

In order to do this, researches on how to check for radiation leakage have been actively conducted. For example, infrared heat, ultrasound, acoustic inspection, etc. are used as a method for checking the radiation leakage of the piping system, but it is difficult to detect a minute initial leak.

Therefore, in order to secure the safety of the radiation safety manager, the radiation workers, and the accident handling personnel from the radiation, a measurement technique capable of accurately and quickly measuring the radiation is required.

Monitoring real-time radiation leakage is a very important factor in preventing accidents. Scintillation radiation measuring instrument for measuring radiation particle energy level is excellent in energy resolution but is not widely available due to its high price. Geiger counter, which is a commonly used radiation measuring instrument, has a wide measurement range, small dose can be detected, and is miniaturized.

However, for a small dose of radiation, the Geiger tube pulse frequency is low and the statistical variance of the signal is very high. Due to this large variance, the Geiger counter finds the average of a long time pulse train, resulting in a slow response time.

Korean Patent Laid-Open No. 10-2016-0080867 (name: gamma ray counter capable of measuring radiation in a wide dose range, July, 2016)

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide a radioactivity measuring apparatus and a radioactivity measuring apparatus which can adjust the bandwidth of a variable low- And a method using the same.

According to another aspect of the present invention, there is provided a radiation measuring apparatus for detecting a radiation intensity, the apparatus comprising: a calculation unit for calculating a period of a pulse train input from a radiation measuring tube for a predetermined period of time, A pulse counter for delivering the period to a variable low pass filter and a bandwidth tracking device; A bandwidth tracking device for estimating a bandwidth of the variable low pass filter based on the period of the transmitted pulse train; And a variable low-pass filter for outputting an average pulse frequency based on the period of the transmitted pulse string and the bandwidth estimated by the bandwidth tracking device.

In this case, if the period of the transmitted pulse train is longer than the reference value, the bandwidth tracking device may lower the bandwidth in proportion to the difference between the period and the reference value of the transmitted pulse train, The bandwidth can be increased in proportion to the difference between the period and the reference value of the transmitted pulse train.

The bandwidth tracking device may further include a bandwidth tracking unit for estimating a bandwidth of the variable low pass filter based on the period of the transmitted pulse train; And a response time estimator for passing the estimated bandwidth through a fixed low pass filter, correcting the estimated bandwidth, and transmitting the corrected estimated bandwidth to the variable low pass filter, wherein the bandwidth of the fixed low pass filter is 0.1 Hz .

According to another aspect of the present invention, there is provided a method of detecting radioactivity in a radiation measuring apparatus, comprising: calculating a period of a pulse train input for a predetermined time; Estimating a bandwidth of the variable low-pass filter based on the cycle of the calculated pulse sequence; And calculating and outputting an average pulse frequency based on the period of the calculated pulse string and the estimated bandwidth.

If the period of the calculated pulse train is longer than the reference value, the estimating may decrease the bandwidth in proportion to the difference between the period and the reference value of the calculated pulse train, In the short case, the bandwidth can be increased in proportion to the difference between the period and the reference value of the calculated pulse string.

Estimating a bandwidth of the variable low-pass filter based on the period of the calculated pulse sequence; And passing the estimated bandwidth through a fixed low-pass filter, correcting the estimated bandwidth, and delivering the variable bandwidth to the variable low-pass filter, wherein the bandwidth of the fixed low-pass filter may be 0.1 Hz .

According to the present invention, through the bandwidth tracking device, the output of the radiation measuring device can have a quick response.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

1 is a block diagram for explaining a configuration of a conventional radiation measuring apparatus.
2 is a block diagram for explaining a configuration of a voltage supply device for a radiation measurement device.
3 is a view for explaining a configuration of a radiation measuring tube for a radiation measuring apparatus.
4 is a block diagram for explaining a configuration of a radiation measuring apparatus according to the present invention.
5 is a block diagram for explaining a configuration of a bandwidth measuring apparatus according to the present invention.
FIG. 6 is a block diagram showing the configuration of a radiation measuring apparatus according to the present invention as a transfer function.
7 is a view for explaining an embodiment of a bandwidth of each low-pass filter included in the radiation measuring apparatus according to the present invention.
8 is a chart comparing the response speed of the output measured according to the embodiment of the present invention and the response speed of the conventional radiation measuring apparatus.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Also, in certain cases, there may be a term selected arbitrarily by the applicant, in which case the meaning thereof will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term, not on the name of a simple term, but on the entire contents of the present invention.

The following embodiments are a combination of elements and features of the present invention in a predetermined form. Each component or characteristic may be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, some of the elements and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments.

In the description of the drawings, there is no description of procedures or steps that may obscure the gist of the present invention, nor is any description of steps or steps that can be understood by those skilled in the art.

Throughout the specification, when an element is referred to as " comprising " or " including ", it is meant that the element does not exclude other elements, do. Also, the terms " part, " " module, " and " module " in the specification mean units for processing at least one function or operation, Lt; / RTI > Also, the terms " a or ", " one ", " the ", and the like are synonyms in the context of describing the invention (particularly in the context of the following claims) May be used in a sense including both singular and plural, unless the context clearly dictates otherwise.

Throughout the specification, when an element is referred to as " comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. Also, the terms " part, " " module, " and " module " in the specification mean units for processing at least one function or operation, Lt; / RTI >

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced.

In addition, the specific terminology used in the embodiments of the present invention is provided to help understanding of the present invention, and the use of such specific terminology can be changed into other forms without departing from the technical idea of the present invention.

Fig. 1 is a view showing a configuration of a conventional radiation measuring apparatus 300. Fig. The radiation measuring apparatus described in Fig. 1 may be a Geiger counter.

Referring to FIG. 1, a conventional radiation measuring apparatus 300 includes a pulse counter 310, a low-pass filter 320, and a display 330. The radiation measuring apparatus 300 may be configured together with the voltage supplying apparatus 100 and the radiation measuring tube 200.

First, the voltage supply device 100 will be described with reference to FIG.

2 is a diagram for explaining the configuration of the voltage supply device 100. As shown in Fig.

The voltage supplying apparatus 100 uses a ringing choke converter (RCC) as a power supply for supplying a high voltage to the radiation measuring apparatus 300. RCC is a self-excited flyback converter that is driven at the boundary of continuous / discontinuous mode, allowing high voltage to be generated with minimal components.

The energy is stored in the transformer T1 from the low drive voltage + VDC to Q1, and at the point when the Q1 collector current saturates, the Q1 base current is simultaneously reduced to perform Q1 off. In Q1 off, the energy stored in T1 forms a high voltage on the secondary side to form 500V. The stability of RCC depends on load, power supply voltage, temperature, etc., and its stability is determined by Q1, T1 and resistance value. Since the RCC operation is highly nonlinear, the device value is determined by an experimental method.

Integral controller is introduced to overcome this analytical difficulty. The error between the reference voltage Vref and the divided output voltage is input to an integrator implemented by an operational amplifier. Since the output energy of RCC is proportional to the collector current saturation point of Q1, Q2 can be controlled to reduce the current flowing in Q1 base. As a result, when the output voltage of the integrator rises, the Q1 base current decreases and the output energy decreases. In the linear operating region of the RCC, the integrator makes the output voltage error to zero. If Vref is safe, only the offset voltage of 10 [mV] of the operational amplifier is present at the error term, so it does not affect the output 500 [V].

Next, the radiation measuring tube 200 will be described with reference to FIG. The radiation measuring tube 200 may be a Geiger tube.

The radioactivity measuring tube 200 is filled with argon or neon gas which is composed of a center electrode and an enclosure and is easy to ionize. A high voltage is supplied between the anode 220 and the cathode 230. When the energy particles are incident on the window 210 to ionize the gas molecules around the electrodes, the ionized electrons move to the anode 220 and gain kinetic energy to generate avalanche. 10 ¹⁰ electrons are generated at about 0.25 [us] and a pulse signal is obtained from an external circuit. The detection sensitivity of the radioactivity measuring tube 200 is close to 100 [%] for the α and β lines and 1 to 2 [%] for the Γ lines. Because the Γ line passes through the detection area of the tube with high probability without interaction with the gas.

Meanwhile, the radiation measuring tube 200 is a pancake type 7314 (LndInc) having an operating voltage of 475 to 675 [V] and a minimum dead time of 40 [us].

Referring to FIG. 1 again, a conventional radiation measuring apparatus will be described.

The radiation measuring apparatus 300 can process data by software using a DSP. In the case of a micro radiation dose, the pulse frequency of the radiation measurement tube 200 is low and the statistical dispersion of the signal is also very large. For example, when natural radiation with a pulse sequence of 40 [CPM] is measured, the dispersion may be very large at an average frequency of 0.6 [Hz]. Also, when the time axis is 10 [s / div], there can be a pulse train of a cycle of about 5 seconds at most. Such a dispersion characteristic may also appear in a case of a 800 [CPM] pulse train. Because of this large dispersion, the radiation measuring apparatus 300 obtains a long time pulse train average and eventually has a slow response time.

The radioactivity measuring apparatus 300 calculates an average using a low-pass filter having a bandwidth of fc 5 [mHz]. The calculation of the average of the pulse sequences using the narrow-band filter processing is performed by a radioactive- ).

Accordingly, the present invention proposes a structure of the radiation measuring apparatus 300 which can have a response time faster than that of the conventional radiation measuring apparatus.

4 is a block diagram for explaining the structure of the radiation measuring apparatus 300 according to the present invention.

4, the radiation measuring apparatus 300 according to the present invention may include a pulse counter 310, a variable low-pass filter 340, and a bandwidth tracking apparatus 350. The radiation measuring apparatus 300 according to the present invention illustrated in FIG. 4 controls the bandwidth fc of the variable low-pass filter 340 for obtaining the average by calculating the cycle of the input pulse string so as to enable quick response .

Specifically, the pulse counter 310 calculates the period of the pulse train input for a short time from the radiation measurement tube 200, and outputs the calculated pulse train cycle to the variable low-pass filter 340 and the bandwidth tracking device 350).

The bandwidth tracking device 350 receiving the calculated pulse train period estimates the bandwidth fc of the variable low pass filter 340 based on the period of the transmitted pulse train. That is, when a slow pulse train arrives, the bandwidth tracking device 350 keeps the bandwidth of the variable low pass filter 340 low, and when a high speed pulse train arrives, the bandwidth tracking device 350 receives the variable low pass filter 340 And increases the response of the variable low-pass filter 340 output.

In other words, when the period of the transmitted pulse string is longer than the reference value, the bandwidth of the variable low-pass filter 340 is lowered, and when the period of the transmitted pulse string is shorter than the reference value, the bandwidth of the variable low- have.

At this time, how much the variable low-pass filter 340 is lowered and increased can be determined in proportion to the difference between the period of the pulse train transmitted to the bandwidth tracing device 350 and the reference value.

Referring to FIG. 5, the bandwidth tracking apparatus 350 may be divided into a bandwidth tracking unit 352 and a response time estimating unit 354.

The bandwidth tracking unit 352 is a device for estimating the bandwidth of the variable low pass filter 340 based on the period of the transmitted pulse train as described above. The response time estimation unit 354 passes the estimated bandwidth to the fixed low-pass filter, corrects the bandwidth estimated by the bandwidth tracking unit 352, and transmits the corrected bandwidth to the variable low-pass filter 340 . At this time, the bandwidth of the fixed low-pass filter may be 0.1 [Hz].

The reason why the response time estimating unit 354 is additionally constructed is to prevent abrupt fluctuations in the output of the variable low-pass filter 340. [

More specifically, the bandwidth tracker 350 determines the bandwidth by referring to the period of the transmitted pulse sequence, that is, the time difference of the input continuous pulse. At this time, the pulse period of the short interval is calculated for a quick response. Pass filter 340 having a bandwidth of 0.1 [Hz] to pass through the variable low-pass filter 340 to prevent the fluctuation of the bandwidth of the variable low-pass filter 340, (340).

For reference, since the pulse train of the radiation measuring tube 200 has a large dispersion value, a bandwidth of 5 to 30 [mHz] is appropriate. When the sensitivity of the radiation measuring tube 200 is lowered, the minimum bandwidth must also be reduced.

6 is a block diagram showing the configuration of the radiation measuring apparatus 300 according to the present invention as a transfer function.

Referring to FIG. 6, the pulse counter 310 includes a bandwidth tracking unit 352 that calculates a frequency from a pulse generation time width of a pulse train input from the radiation measurement tube 200 and includes a low-pass filter having a bandwidth of f1, to the variable low-pass filter 340 having the bandwidth of fc. The bandwidth tracking unit 352 estimates the bandwidth of the variable low-pass filter 340 based on the calculated frequency (i.e., the period of the pulse string), and outputs a response including a low-pass filter having a fixed bandwidth of f2 And delivers the estimated bandwidth to the time estimator 354. [

Then, the response time estimation unit 354 determines the response time and controls the bandwidth of the variable low-pass filter 340, that is, the cut-off frequency fc through the output of the response time estimation unit 354. [

7 shows an example of the bandwidth of each low-pass filter included in the radiation measuring apparatus 300 according to the present invention. That is, FIG. 7 shows a comparison between the variable low-pass filter 340, the bandwidth tracking unit 352, and the response time estimating unit 354, thereby knowing the response time of each filter.

8 is a chart comparing the response speed of the output measured according to the embodiment of the present invention and the response speed of the conventional radiation measuring apparatus.

The top graph of FIG. 8 shows the step response in the case of using the conventional radiation measuring apparatus, and the lower graph in FIG. 8 shows the step response in the case of using the radiation measuring apparatus according to the present invention.

In other words, it shows the step response of a low-pass filter with a fixed 20-second time constant and a variable low-pass filter with a 5-20-second time constant. Fixed bandwidth 8 [mHz] (time constant 20s) When using a low-pass filter, the rise time is very long, and a small ripple appears in the response curve near the steady state. When a variable low-pass filter with a bandwidth of 8 to 30 [mHz] is applied, the output rises very quickly because the bandwidth rises on the rising curve of the initial response. The change of steady state pulsation becomes large due to the effect of high bandwidth.

If the specimen is removed, the input pulse train will be slower, resulting in lower bandwidth and slower output response. As a result, the falling time is the same in both cases. The bandwidth tracking device narrows the bandwidth at low CPMs and broadens the bandwidth at high CPMs so that the output of the average filter at the rising edge has a fast response.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

It is clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

Although the radioactivity measuring apparatus and the radioactivity detecting method as described above have been described with reference to the example applied to the Geiger counter, they can be applied to various radioactivity measuring apparatuses other than the Geiger counter.

100: voltage supply device 200: radiation measuring tube
300: Radioactivity measuring device 310: Pulse counter
320: low pass filter 330: display

Claims (10)

A radioactivity measuring device for detecting the intensity of radioactivity,
A pulse counter for calculating a period of a pulse train input from the radioactive measurement tube for a predetermined time and transmitting the cycle of the calculated pulse train to a variable low pass filter and a bandwidth tracking device;
A bandwidth tracking unit for estimating a bandwidth of the variable low pass filter based on the period of the transmitted pulse train and a control unit for passing the estimated bandwidth through a fixed low pass filter to correct the estimated bandwidth, And a response time estimator for transmitting the response time estimator to the bandwidth estimator. And
A variable low pass filter for outputting an average pulse frequency based on the period of the transmitted pulse string and the bandwidth corrected by the bandwidth tracking device;
. The method according to claim 1,
The bandwidth tracking device
And decreases the bandwidth in proportion to a difference between the period of the transmitted pulse train and the reference value when the period of the transmitted pulse train is longer than the reference value. The method according to claim 1,
The bandwidth tracking device
And increases the bandwidth in proportion to a difference between the period and the reference value of the transmitted pulse train when the period of the transmitted pulse train is shorter than the reference value. delete The method according to claim 1,
Wherein the bandwidth of the fixed low-pass filter is 0.1 Hz. A method of detecting radioactivity by a radioactivity measuring device,
Calculating a period of the pulse string input for a predetermined time;
Estimating a bandwidth of the variable low-pass filter based on the cycle of the calculated pulse sequence; And
And calculating and outputting an average pulse frequency based on the period of the calculated pulse string and the estimated bandwidth,
Wherein the estimating step comprises:
Estimating a bandwidth of the variable low-pass filter based on the cycle of the calculated pulse sequence; And
Passing the estimated bandwidth through a fixed low-pass filter, correcting the estimated bandwidth, and transmitting the corrected bandwidth to the variable low-pass filter;
≪ / RTI > The method according to claim 6,
The estimating step
And decreasing the bandwidth in proportion to the difference between the cycle of the pulse train and the reference value when the cycle of the calculated pulse train is longer than the reference value. The method according to claim 6,
The estimating step
Wherein the bandwidth is increased in proportion to a difference between a period of the calculated pulse string and a reference value when the period of the calculated pulse string is shorter than the reference value. delete The method according to claim 6,
Wherein the bandwidth of the fixed low-pass filter is 0.1 Hz.

Images