WO2006090634A1

WO2006090634A1 - Method for predicting radiation detection value and prediction response radiation detector

Info

Publication number: WO2006090634A1
Application number: PCT/JP2006/302748
Authority: WO
Inventors: Yoshiyuki Shirakawa; Hiro Amano
Original assignee: National Institute Of Radiological Sciences; Amano & Associates, Inc.
Priority date: 2005-02-22
Filing date: 2006-02-16
Publication date: 2006-08-31
Also published as: JP4265813B2; JPWO2006090634A1

Abstract

A radiation detector in which a response is approximated as a primary delay system and, when a time constant T indicative of the feature of response is known, final response N0 is predicted from dose rates or counting rates N1 and N2 at two points in the initial period or the intermediate period of response. When the time constant T is unknown, the final response N0 is predicted from dose rates or counting rates N1, N2 and N3 at three points in the initial period or the intermediate period of response. At the same time, the time constant T is determined and soundness of the radiation detector is evaluated. Consequently, a dose rate in a radiation existing field or a counting rate in a radioactive substance existing field is predicted quickly and accurately and measurement time is shortened.

Description

Specification

Prediction method of radiation detection value and prediction response type radiation detector

Technical field

[0001] The present invention relates to a field where radioactive materials and radiation are used, such as nuclear industry, radiology, radiation industry measurement, non-destructive inspection, etc. Prediction method of radiation detection value for quickly measuring counting rate in a stationary state or while moving, Predictive response type radiation detector using the prediction method, and radiation monitoring method using the radiation detector About.

Background art

A conventional radiation detector used as a radiation detector, for example, a survey meter, obtains a dose rate that is a dose per unit time or a count rate that is a count per unit time. At this time, firstly, a place where the natural radiation level (hereinafter referred to as background) was significantly exceeded while being moved was discovered, and then, at that place, the time was measured for an appropriate time, the indication was stable, and the force was also the final dose rate or counting rate ( It is common to measure the final response value at rest.

[0003] Therefore, when measuring the dose rate of the space and the counting rate of the contaminated part, for example, when an emergency exposure accident occurs, measure a wide range while moving the radiation detector such as a survey meter, It took a huge amount of time to complete the measurement because it stopped at a place where it was recognized as abnormal and spent 30 seconds of force over 60 seconds. When reading a measurement value while moving a survey meter, etc. to inspect the contaminated area, for example, if the distance to the measurement target is 10 mm, the time constant is 10 seconds, and the moving speed is 50 mm per second, the output is 10% of the final response value when stationary. The current situation is that it is difficult for non-experts to even find anomalous parts because the percentage drops from 15% to 15%.

[0004] In addition, if human body contamination inspection takes a long time per person, the amount of exposure of the inspector becomes a serious problem if the inspection is delayed for a large number of people. Furthermore, even in daily radiation management, there are problems that it takes a long time if there are many measurement locations.

[0005] On the other hand, a predictive response body that predicts the final response value of body temperature is similar to the present invention. Although thermometers have been put to practical use, thermistors, etc. have a large number of electrons and the time constant is constant and known, so it is easy to predict, and as a stochastic phenomenon, radiation is emitted in units of one. It cannot be used as it is for radiation detectors with large variations.

Disclosure of the invention

[0006] The present invention has been made to solve the above-described conventional problems, and it is an object of the present invention to make it possible to predict a radiation detection value and to greatly shorten the measurement time.

[0007] Another object of the present invention is to make it possible to predict a radiation detection value at the time of movement and to greatly reduce the measurement time.

[0008] Further, another object of the present invention is to make it easier for non-experts to find abnormal parts.

[0009] In the present invention, when a dose rate or a counting rate is obtained using a radiation detector such as a survey meter in the presence of radiation or a radioactive substance, there is an initial stage before reaching a final response value. In the response stage, the above-mentioned problem is solved by predicting the final response value using a dose rate or counting rate of two or more points.

[0010] Also, using the two dose rates or counting rates N, N in the initial or mid-term response

1 2

N = (N— C * N) / (l -C)

0 2 1

Where C = exp (— Δ t / T) 0

A t: Time between two points

T: Response time constant

The final response value N can be predicted quickly.

0

[0011] Alternatively, a dose rate or count rate of 3 in the initial or mid-term response N, N

1 2

, N

Three

N = (N * N—N * N) / (2 * N—N—N)

O 2 2 1 3 2 1 3

To predict the final response value N, so even if the time constant is unknown

0

It is a thing.

[0012] At the same time, a time constant representing the characteristics of response is obtained to enable evaluation of the soundness of the radiation detector. [0013] According to the present invention, the dose rate, which is the dose per unit time, and the count rate, which is the count per unit time, can be obtained in about 5 seconds, which is half of that when the time constant is 10 seconds. It is possible to greatly reduce the measurement time that generally required 30 to 60 seconds. Therefore, it is useful for both radiation measurement at the time of an accident and normal radiation measurement.

[0014] At the same time, the time constant can be obtained to evaluate the soundness of the radiation detector.

[0015] The present invention approximates the response of the radiation detection value as a first-order lag system, and when the time constant representing the characteristics of the response is known, two dose rates or counting rates in the initial or mid-term of the response force Final response value Is to be predicted. Alternatively, if the time constant representing the characteristics of the response is unknown, the final response value is predicted from the three dose rates or counting rates in the initial or mid-term of the response.

[0016] Here, the initial period of response means that the measurement starting force as shown in Fig. 1 is about 0.5 times the time constant T, and the middle period of response means that the time constant T is 0.5 to 1.5. For example, when T = 10 seconds, 0 to 5 seconds and 5 to 15 seconds, respectively.

[0017] The present invention also provides an output measured by moving the radiation detector when the dose rate or counting rate is obtained using a radiation detector such as a survey meter in the presence of radiation or a radioactive substance. The final response value obtained when the measurement is performed with the radiation detector stationary in the vicinity of the output value (also referred to as response value) using two or more measured values such as dose rate or counting rate. The problem is solved as predicted.

That is, the response of the radiation detection value is approximated as a first-order lag system, a time constant representing the response characteristic is set in advance, and the dose rate or count that is the output value measured while moving the radiation detector. Using two or more measured values such as the rate, predict the final response value obtained when the output value is measured and measured in the vicinity.

[0019] Specifically, if the elapsed time from the start of the response is t seconds and the time constant of the first-order lag system is T seconds, the response value N in the middle is

N = N (l -exp (-t / T))

0

Can be shown. The response value at elapsed tl seconds is Nl, the response value at elapsed time t2 seconds is N2, and the time constant T is set in advance. C = exp [-(t -t) / T]-(2)

twenty one

Is a constant. From equation (1)

N = N * (1— exp (— t ZT)) --- (3)

1 0 1

Ν = Ν * (l— exp (— t ZT)) --- (4)

2 0 2

It becomes. However, t> t. If these equations (3) and (4) are simultaneously solved for N, the elapsed time

2 1 0

Initial value N in t seconds, and similarly the response change up to t seconds elapsed N-N

1 1 2 2 1 The following equation that can be interpreted as multiplying by the width ratio 1Z (1—C)

N = N + (N -N) / (l-C) --- (5)

0 1 2 1

Is obtained.

[0020] Using Fig. 2 to Fig. 4, we show that equation (5) holds at any stage during response. Considering the radiation entering the radiation detector as the input, any input time series can be approximated sufficiently by the synthesis of a rectangular pulse lasting a certain amount of time. I in Fig. 2 is an input and lasts from 10 seconds to 15 seconds, and the counting rate is lOOOcpm. The input of this rectangular pulse is considered to be the composition of the step input Iu of the counting rate lOOOcpm, which continues for 10 seconds at the time in Fig. 3, and the Id of 1 OOOcpm, which continues from the time 15 seconds. The responses of inputs Iu and Id are Ru and Rd shown in equation (1). Therefore, the response R of the rectangular pulse input I is the sum of Ru and Rd.

Next, the behavior of the equation (5) is clarified in FIG. Substituting any two points, P1 and P2, from 10 to 15 seconds, when Ru and R completely overlap, lOOOcpm is obtained. Next, consider the case of 15 seconds or longer. Consider two points on R, P3 and P4, and P5, P7 and P6 and P8 at the same time as P3.

P3 = P5 + P7 --- (6)

P4 = P6 + P8 --- (7)

Is established.

[0022] Substituting P3 and P4 into equation (5)

NO = P3 + (P4-P3) / (l-C)

= (P5 + P7) + ((P6 + P8) (P5 + P7)) / (l-C)

= (P5 + (P6-P5) / (l-C)) + (P7 + (P8-P7) / (l-C))

= (1000) + (-1000) = 0-(8)

It becomes. That is, when the input I after time 15 seconds becomes 0, equation (5) shows 0.

Therefore, Equation (5) predicts the input value (matching the final response value) using the response value at any stage of the response, that is, the final response value of the radiation detector here. It shows what can be done.

[0024] Consider a certain time (response value N) when the radiation detector is moving and a time immediately after (response value N).

1 2 and if the air dose rate or counting rate of the place moved at this time is constant, the radiation detector is placed near the passing place according to Equation (5) regardless of the time selection and the moving speed. It is possible to predict the final response value that is obtained when measurement is performed at a stationary position.

[0025] Figure 5 shows the input I, its response R, and the predicted value P when there is contamination at one location (corresponding to travel speed X elapsed time). Input I and predicted value P match.

The present invention is effective not only when there is only one contamination as shown in FIG. 5, but also when there are a plurality of contaminations as shown in FIG. 6, or when there are continuous contaminations as shown in FIG.

[0027] Figure 6 shows inputs I, I, and I when the remote location is contaminated (corresponding to travel speed X elapsed time).

1 2 Response R and predicted values P, P

1 2 is shown. Input I

1 and predicted value P

1 matches, input I

2 and predicted value P

2 also agree.

[0028] Figure 7 shows the inputs I and I when there is contamination in an adjacent location (corresponding to travel speed X elapsed time)

1 2

, Its response R and predicted values P, P

1 2 is shown. Input I

1 and predicted value P

1 matches, input I

2 and predicted value P

2 also agree.

[0029] It should be noted that the predicted value with the final response value N can be made highly accurate using the moving average.

0

The

[0030] The present invention also provides a predictive response type radiation detector employing the radiation detection value prediction method described above.

[0031] Further, both the predicted value and the measured value can be displayed.

[0032] In addition, the horizontal axis corresponds to time or distance, and the vertical axis can display both predicted values and measured values on a liquid crystal or the like.

[0033] The vertical axis corresponds to time or distance, and the horizontal axis can display both predicted values and measured values on a liquid crystal or the like. [0034] In addition, the positional information by GPS and the predicted value and the measured value can both be displayed on the map by a liquid crystal or the like.

[0035] Further, an alarm that is issued when the predicted value is greater than or equal to the threshold value is clearly indicated by sound or light. Here, sound means auditory warning means such as sirens and automatic announcements, and light means visual warning means such as lamps, LEDs, red lights and red rotating lights.

[0036] Further, an alarm that is issued when the predicted value is equal to or greater than a threshold value is transmitted to a management device or a control device by communication. As a result, for example, an alarm can be automatically transmitted to the mobile phone or monitoring monitor of the person concerned. Alternatively, the alarm can be synchronized with position information from a position detection device such as GPS, and at the time of alarm, the surveillance camera can be pointed to the alarm generation position, or the emergency door can be automatically closed. Furthermore, it is possible to set multiple threshold values and rank them automatically and automatically create a ranking map such as the counting rate if the dose rate is automatically mapped.

[0037] The present invention also provides a radiation monitoring method characterized by using the movement prediction response type radiation detector.

[0038] According to the present invention, a dose rate that is a dose per unit time and a count rate that is a count per unit time can be predicted while moving without stopping. For example, when calculating the counting rate of a contaminated spot where a certain reference point force is around 5 OOmm with the survey meter stationary, Fig. 8 (Overall), Fig. 9 (Detail) and Fig. 10 (Rise of measured value) When the time constant is 10 seconds and the moving speed is 50 mm per second, the maximum predicted value, that is, immediately after passing the 500 mm position, the elapsed time is approximately 450 mm to 550 mm. It can be calculated in 2 seconds. Since it is not necessary to stop the measurement, the measurement time required from 30 to 60 seconds per measurement point can be greatly reduced. Therefore, it is useful for both accidental radiation measurement and normal radiation measurement. In addition, since the measured value at rest is predicted, it becomes a larger value than the actual measured value, so even an expert can easily find the abnormal part.

In addition, when the output value decreases after passing through the contaminated portion, the predicted value corresponds to the background, so that the end of the contaminated portion can be known. That is, when the predicted value rises, the start of the contaminated part is known, and when the predicted value power background is reached, the end of the contaminated part is known. It can be done.

Brief Description of Drawings

[0040] FIG. 1 is a diagram for explaining definitions of terms used in the present invention.

FIG. 2 is a diagram showing a rectangular pulse input for explaining the principle of the present invention.

[Figure 3] Diagram showing step input and response curve

[Figure 4] Diagram showing the prediction principle

[Fig.5] Diagram showing prediction of single contamination

[Fig.6] A diagram showing the prediction of remote contamination

[Figure 7] Figure showing the prediction of close contamination

[Figure 8] Diagram showing the entire response curve and prediction curve

[Fig.9] Detail of response curve and prediction curve

[Fig.10] Enlarged view of the rise of measured values

FIG. 11 is a front view showing the configuration of the first and second embodiments of the present invention.

[Fig. 12] Block diagram showing the configuration of the detector.

FIG. 13 is a diagram for explaining the measurement principle of the present invention.

[Fig.14] Diagram showing details of riser

FIG. 15 is a diagram showing a response and a predicted response by the detector of the embodiment.

[Fig.16] Detail view of rising part

FIG. 17 is a diagram showing a moving average in the first embodiment.

FIG. 18 is a diagram showing a moving average in the second embodiment.

FIG. 19 is a front view showing the configuration of the third embodiment of the present invention.

FIG. 20 is a block diagram showing the configuration of the detector of the third embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

A first embodiment of the radiation detector according to the present invention includes a probe 20 disposed in the vicinity of a radiation source 10 to be measured as shown in FIG. 11, and an output of the probe 20 via a cable 22. It is provided with a detector 30 inputted as

[0043] The detector 30 includes a current value indicator 34 for displaying an actual measurement value every moment, and the present invention. An analog display unit 32 having a predicted value indicator 36 indicating the predicted value, a digital display unit 40 capable of switching and displaying the current value and the predicted value, and an operation unit 42.

[0044] Inside the detector 30, an amplifier 50 that amplifies the signal from the probe 20 as shown in detail in FIG. 12, and the output of the amplifier 50 is converted into a dose rate or a count rate. A rate meter 52 as a value, and a predictive calculator 54 that receives a signal from the rate meter 52 and predicts and outputs a final response value according to the present invention.

Hereinafter, the operation of the predictive calculator 54 of the first embodiment used when the time constant is known will be described.

In the present embodiment, the process from when radiation is incident on the probe 20 of the radiation detector, detected, output by the rate meter 52, and instructed is approximated by a “first-order lag system”. Final response value (also simply referred to as final value) N is 100, the elapsed time from the start of response is t (seconds),

0

If the time constant of the first-order lag system is T (seconds), the response value N in the middle is the response curve in Fig. 13, that is,

N = 100 (l-exp (-t / T)) --- (9)

Can be shown. FIG. 14 shows the response curve N from the initial stage to the middle stage. The elapsed time t is t (seconds), the response value at that time is N, the minute time is At (seconds), and the response value at that time is N

1 1 2

Furthermore, let N be the response value after At (seconds). Here, as in this embodiment, the time constant T is set in advance.

Three

If you are divided into

C = exp (-At / T) --- (10)

Then,

N = N * (1— exp (— tZT)) to (11)

Ten

N = N * (1— C * exp (— tZT)) --- (12)

2 0

It becomes. Solving these (3) and (4) for N,

0

N = (N C * N) Z (1— C)

0 2 1

Is obtained. In this case, Ν = 100 is the solution. Therefore, early or middle of response

0

Measure the two response values Ν and Ν at the initial stage and substitute them into the simultaneous equations (11) and (12).

1 2

For example, the solution can be obtained without waiting for the time to reach the final response value Ν, greatly reducing the measurement time.

0

it can.

Next, the operation of the predictive calculator 54 of the second embodiment used when the time constant is unknown will be described. To do.

[0048] In this embodiment, the time constant T is not divided in advance.

C = exp (-At / T) --- (14)

Then,

N = N * (1— exp (— tZT)) --- (15)

N = N * (1— C * exp (— tZT)) "-(16)

2 0

N = N * (1— C * C * exp (— tZT)) --- (17)

3 0

It becomes. When these equations (15), (16), and (17) are combined to eliminate C and solve for N,

0

N = (N * N—N * N) Z (2 * N—N—N)

Ο 2 2 1 3 2 1 3

0

In response to the simultaneous equations (15), (16), and (17), the three response values Ν, Ν, and 測定 are measured at the initial stage.

one two Three

And solve it without waiting for the time to reach the final response value Ν.

0

Can be shortened to width.

[0049] At the same time, the time constant Τ

T = -t / ln [(N -N) / (N -N)] "-(19)

3 2 2 1

Can be calculated as The time constant represents the response of the entire detector from input to output, and the time of the entire system is being measured regardless of the intensity of the radioactivity to be measured, the number of emitted radiation, the number of detected radiation, etc. Since the constant is constant, the deterioration of the element can be known by evaluating the magnitude of the change in the obtained time constant and the soundness of the aging force detector itself.

[0050] When the air dose rate is measured using the radiation detector of the above-described embodiment, the SvZh value can be read in about 5 seconds per measurement place. It is also possible to monitor only one point continuously. When measuring surface contamination, the count rate cpm value can be read in about 5 seconds per measurement point. Therefore, it is possible to monitor radiation with a force of about 30 seconds per point, which greatly reduces the measurement time.

[0051] In the embodiment, since the current value and the predicted value are displayed together, it is possible to visually observe how the current value approaches the predicted value. It is also possible to display only the predicted value. [0052] Further, in the embodiment, since the moving average is used, the emission is a probability phenomenon in units of one, and it is possible to reliably predict the dose rate and counting rate of radiation with large variations.

[0053] The count rate was measured using the first and second embodiments. The response curve N in Fig. 15 (overall) and Fig. 16 (initial to mid-term) shows the time variation of the actual GM survey meter output. The experimental conditions were such that the tip of the probe 20 was located at a distance of 1 cm from the 37,000 becquerel source of strontium 90 as the source 10. The detector time constant T was 10 seconds. The counting rate N in a stable state after a lapse of 60 seconds or more was 26800 cpm.

0

[0054] The minute time At was set to 0.2 seconds.

In the example of the first embodiment, N is obtained from two consecutive points on the response curve N as shown in FIG. 17 according to the equation (13). Next, N was calculated in the same way from the end point of these two points and the next point. start point

0 0

This scan was repeated 30 times while shifting one by one, and the average value of 30 times was obtained and displayed as a prediction response curve N ′. The initial predicted value was 26944 cpm. This was very close to the final value NO of 26800cpm. The first predicted value of the predicted response curve N 'was obtained 6 seconds after the start of the measurement (= 0.2 seconds x 30 times). It can be seen that the measurement time has been greatly reduced.

Next, in the example of the second embodiment, N was obtained from three consecutive points as shown in FIG. 18 according to the equation (18). Next, N is similarly calculated from the three intermediate points, the end point, and the next point.

0 0 This scan was repeated 30 times while shifting the starting point one by one, and the moving average value of 30 times was obtained. The initial value of this predicted value was 26370 cpm. This is a final value of N 268

0

It was very close to OOcpm. The first predicted value was obtained 6 seconds after the start of measurement. It can be seen that the measurement time has been greatly shortened. The time constant T was calculated to be 8 to 12 seconds with respect to the true value of 10 seconds. We can not ask that the detector used for this measurement was operating normally.

[0057] In the above-described embodiment, 力 1; is a force that has been set to 0.2 seconds and the moving average number of times is 30 times.

It is possible to set At to 0.1 second and the moving average count to 60 times, or At to 1 second and moving average count to 6 seconds. If the source is strong, obtain the predicted value 3 to 1 second after the start of measurement. Next, the third embodiment of the radiation detector according to the present invention applied to the movement prediction is a program that moves directly above the radiation source 110 simulating the contaminated part to be measured as shown in FIG. And a detector 130 into which the output of the probe 120 is input via a cable 122.

[0059] The detector 130 includes an analog display unit 132 including a measurement value guide 134 that displays an actual measurement value every moment, a prediction value guide 136 that indicates a prediction value according to the present invention, and a measurement value. The digital display unit 140 capable of switching and displaying the predicted value and the operation unit 142 are provided.

[0060] Inside the detector 130, as shown in detail in FIG. 20, an amplifier 150 that amplifies the signal from the probe 120, and the output of the amplifier 150 is converted into a dose rate or a count rate and measured. A rate meter 152 that is a value, and a prediction calculator 154 that receives a signal from the rate meter 152 and outputs a predicted value according to the present invention.

Hereinafter, the operation of the predictive calculator 154 will be described.

In the present embodiment, the process from when radiation is incident on the probe 120 of the radiation detector, detected, output by the rate meter 152, and instructed is approximated by a “first-order lag system”. When stationary, set the final response value at the center axis position of the probe 120 to NO, measure the response values N and N at two points when the measured value rises during movement, and use equation (5). Assigned to

1 2

If solved, the final response value at rest can be obtained as a solution N without moving the probe 120 of the radiation detector, and the measurement time can be greatly shortened. And decrease the measured value.

0

Response value of 2 points in a few steps N

1, Measure N, substitute into equation (5) and solve, radiation detector 2

The solution corresponding to the background, which is the final response value when the probe 120 is stationary, can be obtained without moving the probe 120.

[0063] When measuring the air dose rate using the radiation detector of the above embodiment, if there is an abnormal rise with respect to the background when passing through the measurement point, it takes about 2 seconds; z Sv Zh The value can be read. When measuring surface contamination, the count rate cpm value can be read in about 2 seconds if there is an abnormal rise in the background when passing through the contaminated area. Therefore, it is possible to monitor radiation by reducing the measurement time significantly from the conventional time required per point of 30 to 60 seconds.

[0064] In the embodiment, since the measured value and the predicted value are displayed together, the measurement is performed. When the fixed value rises, it can be visually observed how the predicted value rises and reaches the maximum at the same time. It is also possible to display only the predicted value. The display is either digital or according to the guidelines. Or you can show the pointers on the LCD.

[0065] The counting rate of the radiation source simulating the contaminated part was measured. The response curves N shown in Fig. 8 to Fig. 10 show the change with the position of the measured value which is the output of the actual GM survey meter. The source 110 is a thin, sealed source of strontium 90 3700 becquerel with a diameter of 20 mm. The probe 120 was arranged so that the tip of the probe 120 was located at a position 1 Omm immediately above the radiation source 110. The detector time constant T was 10 seconds. The maximum count rate was 26400 cpm at a distance of 10 mm between the center of the probe tip of the GM survey meter and the radiation source in a stable state after 60 seconds or more after stationary. This was the maximum measured value at rest (also called the maximum final response value) N max. The background was below lOOcpm.

0

[0066] The moving speed of the survey meter was set to 50 mm per second, and sampling was performed every 5 mm, that is, at intervals of 0.1 second.

[0067] In the embodiment, a radiation source simulating the contaminated part as shown in FIGS. 8 to 10 is arranged at a position of 500 mm, the movement start position Omm force, the movement end position 1500 mm, and the rising portion of the response curve N NO was calculated from the two consecutive points according to Equation (5). Next, N was calculated in the same way as the end point of these two points and the next point force. Repeat this scan 5 times while shifting the start point by 1 to 5

0

The moving average value was obtained and displayed as a predicted response curve N ′. The maximum predicted value was 2 6410 cpm. This is the maximum final response value N max of 26400cpm at rest.

0

It was very close. It can be seen that the maximum predicted value of the predicted response curve N 'is obtained about 2 seconds after the rise. A value sufficiently larger than the background due to natural radiation is output as a predicted value, so even an unskilled person can easily find an abnormal part. In addition, around 80 cpm was predicted from the response values of the two points at the stage of decrease in the measured value, and it was predicted that it was equivalent to the knock ground.

[0068] In the present embodiment, since a moving average is used, the emission is a stochastic phenomenon in units of one, and it is possible to reliably predict the radiation dose rate and counting rate with large variations. Industrial applicability

[0069] The present invention can be used, for example, as an air dose rate meter using a Nal scintillator. wear. It can also be used as an area monitor. It can also be used as a counting rate meter using a GM tube. For example, it can be used as a floor monitor using a GM counter. It can be arranged in a fixed manner, or can be used in a portable manner like a survey meter, and various monitoring methods can be provided. A variety of monitoring methods can be provided. It can also be installed in monitoring cars, monitoring boats, helicopters, etc., and monitoring while moving can be performed quickly and reliably.

Claims

The scope of the claims

[1] When radiation is present in the presence of radioactive material, the dose rate or counting rate is calculated using a radiation detector.

A method for predicting a radiation detection value, wherein a final response value is predicted using a dose rate or a counting rate of two or more points at an initial or intermediate response stage before reaching a final response value.

[2] In claim 1, using the two dose rates or counting rates N, N in the initial or mid-term response,

1 2

N = (N— C * N) / (l-C)

0 2 1

Where C = exp (― At / T)

At: Time between two points

T: Response time constant

A method of predicting a radiation detection value, wherein the final response value N is predicted by

0

[3] In claim 1, using three dose rates or counting rates N, N, N in the initial or mid-term response,

one two Three

N = (N * N -N * N) Z (2 * N—N—N)

0 2 2 1 3 2 1 3

0

4. The method for predicting a radiation detection value according to claim 3, wherein a time constant representing a response characteristic is obtained at the same time to evaluate the health of the radiation detector.

[5] I have radiation!ヽ is in the presence of radioactive materials! When using a radiation detector to determine the dose rate or counting rate,

Using two or more measured values such as dose rate or counting rate, which are output values measured while moving the radiation detector,

A method for predicting a radiation detection value, comprising predicting a final response value obtained when measurement is performed with a radiation detector stationary in the vicinity where the output value is obtained.

[6] In claim 5, the dose rate or count obtained at a certain time t and a time t thereafter.

1 2

The rate output values are N and N, respectively, and the time constant T set in advance is used.

1 2

N = N + (NN) / (lC) Where C = exp [— (t -t) / T]

twenty one

Is used to predict the final response value of the output value at rest as N.

0

Method for predicting movement of output value.

[7] In any one of claims 1 to 6, the predicted value with the final response value N is increased in accuracy.

0

A method for predicting a radiation detection value, characterized by using a moving average for the purpose.

[8] A prediction response type radiation detector, wherein the radiation detection value prediction method according to any one of claims 1 to 7 is employed.

[9] The predictive response type radiation detector according to claim 8, wherein both the predicted value and the actually measured value can be displayed.

[10] The predictive response type radiation detector according to claim 8, wherein the horizontal axis represents time or distance, and the vertical axis has a display capable of displaying both the predicted value and the measured value.

[11] The predictive response type radiation detector according to claim 8, further comprising a display in which the vertical axis corresponds to time or distance and the horizontal axis can display both the predicted value and the measured value.

[12] The predictive response type radiation detector according to claim 8, further comprising a display capable of displaying both position information by GPS and a predicted value and a measured value on a map.

[13] The predictive response type radiation detector according to claim 8, wherein an alarm issued when the predicted value is equal to or greater than a threshold value is clearly indicated by sound or light.

14. The predictive response type radiation detector according to claim 8, wherein an alarm that is issued when the predicted value is equal to or greater than a threshold value is transmitted to a management device or a control device by communication.

[15] A radiation monitoring method using the radiation detector according to any one of [8] to [14].