JP5755116B2 - Radiation measurement equipment - Google Patents

Description

  The present invention relates to a radiation measurement apparatus used in a nuclear reactor facility, a spent fuel reprocessing facility, or the like.

  Conventional radiation measurement devices include a radiation detector that detects radiation and outputs an analog pulse, a pulse height discriminator that receives analog pulses and discriminates those within a predetermined peak value range, and a signal that discriminates the waveform. There is a noise removal circuit that removes a noise pulse from a pulse, stores a noise waveform determination result (waveform information) for each analog pulse, and analyzes a noise generation factor as necessary.

  For example, Patent Document 1 presents a pulse signal detection device provided with a single AD converter that analyzes the waveforms of pulse signals that have passed through a pulse height discriminator one by one and passes only normal pulse signals as noise removal means. Has been. In this example, the AD converter inputs waveform information for identifying the type of harmful noise to the calculator, and the calculator removes the noise through the wave height discriminator even if harmful noise has entered. The pulse count rate is calculated based on the count value of the pulse signal.

JP 2003-28963 A

  The noise removal circuit in a conventional radiation measurement device is a noise waveform whose maximum peak value exceeds the measurement target upper limit level, “excessive wave height”, and whose minimum peak value exceeds the reference level of reverse polarity. Were identified as “reverse polarity wave height excessive”, those having a pulse width outside the predetermined range were identified as “pulse width abnormality”, and those having a noise waveform were removed from the pulse signal.

  However, if the waveform undershoot does not reach the reference level or less, it was not identified as a noise waveform. This waveform of “undershoot shortage” is a waveform peculiar to noise caused by a defect in the HV signal superposition line in the radiation detector, and is representative of noise in the radiation detector. For this reason, in the conventional radiation measurement device, when the indicator value (counting rate or radiation dose) increases, it is difficult to judge whether it is due to an increase in radiation or the influence of noise, and the reliability is insufficient. Met.

  The present invention has been made to solve the above problems, and accurately and promptly determines whether the cause of the increase in the indicated value (counting rate or radiation dose) is due to an increase in radiation or the influence of noise. An object of the present invention is to obtain a radiation measuring apparatus capable of performing the above.

The radiation measurement apparatus according to the present invention includes a radiation detection unit that detects radiation and outputs an analog pulse, and a waveform measurement that inputs the analog pulse, measures a waveform of a pulse wave having a level higher than a predetermined level, and outputs waveform data. And waveform data input from the waveform measuring means, and output a count value A obtained by counting a pulse a of a waveform satisfying a predetermined peak height range condition and a count value B obtained by counting a pulse b of a noise waveform Means, a count value A and a count value B are input at a fixed cycle, a count rate m and a radiation dose p (A) based on the count value A are obtained, and a predetermined number of calculation cycles of the count value A and the count value B Calculating means for obtaining the noise mixing rate B ′ / A ′ from the moving average values A ′ and B ′, and at least one of the counting rate m and the radiation dose p (A) output from the calculating means. Need Display means for displaying the noise mixing rate, and the waveform analysis means has noise determination means for identifying the characteristic having the noise waveform from the input waveform data, and the noise determination means has a wave height. Reverse polarity wave height excess determination means for identifying a waveform having a portion whose reverse polarity deviates from a predetermined level, pulse width abnormality determination means for identifying a waveform whose pulse width deviates from a predetermined range, and under-falling of the pulse and undershoot shortage determination means for identifying a waveform chute does not reach the predetermined range of the reverse polarity, see contains the crest excessively determining means for identifying a waveform wave height exceeds a predetermined level, the waveform analysis means, opposite polarity pulse height excessive Each pulse of the waveform determined as noise by each of the determination means, the pulse width abnormality determination means, the undershoot shortage determination means, and the wave height excess determination means Counted values B1, B2, B3, B4 are output, and the calculation means A ′ and B1 ′, which are moving average values of a predetermined number of calculation cycles of the count value A and the count values B1, B2, B3, B4, The individual noise mixing rates B1 ′ / A ′, B2 ′ / A ′, B3 ′ / A ′, and B4 ′ / A ′ are obtained from B2 ′, B3 ′, and B4 ′ .

According to the radiation measurement apparatus of the present invention, the noise determination means of the waveform analysis means includes a reverse polarity wave height excess determination means, a pulse width abnormality determination means, an undershoot shortage determination means, and a wave height excess determination means , each determination means. Since the individual noise mixing rate is obtained based on the count values B1, B2, B3, B4 obtained by individually counting the pulses of the waveform determined as noise by the above, in the radiation detector that could not be identified conventionally Noise waveforms peculiar to noise can be identified and counted, and a highly reliable noise mixing rate can be obtained. Further, since the individual noise mixing rate can be displayed on the display means as necessary, the cause of the increase in the counting rate m or the radiation dose p (A) displayed on the display means is due to the increase in radiation or noise. In addition, it is possible to accurately and quickly determine whether the noise is caused by an abnormality of the radiation detector or external noise .

It is a block diagram which shows the structure of the radiation measuring device which concerns on Embodiment 1 of this invention. It is a figure explaining the kind of waveform identified by the waveform analyzer of the radiation measuring device which concerns on Embodiment 1 of this invention. It is a figure which shows operation | movement of the calculator of the radiation measuring device which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the radiation measuring device which concerns on Embodiment 3 of this invention. It is a figure which shows the example of a display in the indicator of the radiation measuring device which concerns on Embodiment 3 of this invention. It is a block diagram which shows the structure of the radiation measuring device which concerns on Embodiment 4 of this invention. It is a block diagram which shows the structure of the radiation measuring device which concerns on Embodiment 5 of this invention. It is a figure which shows operation | movement of the calculator of the radiation measuring device which concerns on Embodiment 5 of this invention.

Embodiment 1 FIG.
Hereinafter, a radiation measuring apparatus according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of the radiation measuring apparatus according to the first embodiment. The radiation measurement apparatus according to the first embodiment is a radiation measurement apparatus used for monitoring the radiation dose in a nuclear reactor facility, a spent fuel reprocessing facility, etc. As shown in FIG. 1, a pulse amplifier 2, a high-speed AD capacitor 3, a waveform analyzer 4, a calculator 5, a memory 6, and a display 7.

The radiation detector 1 serving as radiation detection means detects radiation and outputs an analog pulse, and the pulse amplifier 2 amplifies the wave height of the analog pulse output from the radiation detector 1 and outputs the amplified pulse. A high-speed AD capacitor 3 (hereinafter referred to as a high-speed ADC 3) that is a waveform measuring means inputs an analog pulse output from the radiation detector 1 and amplified by the pulse amplifier 2, measures the waveform of the analog pulse, and stores waveform data. Output.

  The high-speed ADC 3 measures the voltage in a time-sharing manner, and always updates a predetermined number of voltage data and stores them as a package. Outputs voltage data arranged in a time series in a period that combines a predetermined time from when the latest voltage data becomes equal to or higher than the trigger level and a predetermined time immediately before the trigger level as waveform data of the analog pulse. . The trigger level of the high-speed ADC 3 is set to a lower limit level as a signal waveform, for example.

  The waveform analyzer 4 as a waveform analysis means analyzes the waveform data input from the high-speed ADC 3 and counts the count value A obtained by counting the pulse a of the waveform satisfying a predetermined peak height range condition and the noise waveform pulse b. The numerical value B is output. The noise determination logic 41 as noise determination means analyzes the input waveform data with respect to the maximum peak value, the minimum peak value, and the pulse width, and identifies those having noise waveform characteristics.

  The noise determination logic 41 includes a reverse polarity wave height determination logic 411 (hereinafter referred to as b1 determination logic 411) which is a reverse polarity wave height determination means, and a pulse width abnormality determination logic 412 (hereinafter referred to as b2) which is a pulse width abnormality determination means. Determination logic 412), undershoot shortage determination logic 413 (hereinafter referred to as b3 determination logic 413) as undershoot shortage determination means, and wave height excess determination logic 414 (hereinafter referred to as b4 determination logic 414) as wave height excess determination means. And OR logic 415 is included. The OR logic 415 outputs a digital pulse b when there is an input from any of the determination logics 411 to 414 b1 to b4.

  The noise determination logic 41 sequentially performs determinations by the determination logics 411 to 414 of b1 to b4, and is reset when execution of all determinations is completed or when there is an output from the OR logic 415. In the first embodiment, the determination order of the determination logics 411 to 414 for b1 to b4 is not particularly defined.

  When the maximum peak value data of each waveform data satisfies a predetermined peak height condition, the peak height a determination logic 42 determines that the peak height is within the peak range and outputs a digital pulse a. The first counter 43 counts the digital pulse b corresponding to the noise determination, and outputs the count value B at a fixed period. Further, the second counter 44 counts the digital pulse a corresponding to the determination in the wave height range, and outputs the count value A at a constant cycle.

  The computing unit 5 that is a computing means inputs the count value A and the count value B at regular intervals, obtains a count rate based on the count value A, and outputs a radiation dose p (A) obtained by converting the count rate into an engineering value. To do. When the integrated value is M, the count rate is m, the standard deviation is σ, the time constant is τ, the constant γ, the constant λ, and the constant α, their relationship is expressed by the following equations 1 to 5.

σ = 1 / (2mτ) ^1/2 (Expression 1)
τ = 1 / (2mσ ² ) (Formula 2)
m = e ^γM = 2 ^{γM / ln2} (Formula 3)
γ = 2σ ² = 1 / (mτ) = 2− ^λ ln2 (Expression 4)
α = 11−λ (Formula 5)

  Accordingly, assuming that the current count value is A (current), the current integrated value is M (current), the previous integrated value is M (previous), and the fixed cycle time is ΔT, the following formulas 6 and 7 are set for each fixed cycle. Can be calculated to obtain the current count rate m (current). Α is a weighting constant for integration. For example, α = 0 when σ = 0.013, α = 2 when σ = 0.026, α = 4 when σ = 0.052, and σ = In the case of 0.014, α = 6.

M (current) = M (previous) +2 ^α × {A (current) −m (previous) × ΔT} (Expression 6)
m (current) = e ^{γM (current)} = 2 ^{γM (current) / In2} (Expression 7)

  The computing unit 5 performs warning determination based on the radiation dose p (A), and outputs a warning when the radiation dose p (A) is equal to or higher than a predetermined level. Further, a moving average value of a predetermined number of calculation cycles for the count value A and the count value B is obtained as A ′ and B ′, respectively, and a ratio B ′ / A ′ of B ′ with respect to A ′ is obtained as a noise mixing rate.

  The memory 6 stores a necessary number of radiation doses p (A), alarms, noise mixture rates, and the like. The display 7 which is a display means always displays the count rate m (current), and displays an alarm together with the count rate m (current) when an alarm is output from the calculator 5. Furthermore, it is possible to display the noise mixture rate at the time of occurrence of the alarm and before and after that as necessary.

  Next, characteristics of each noise waveform identified by the noise determination logic 41 of the waveform analyzer 4 will be described with reference to FIG. In FIG. 2, (a) is a normal signal waveform, that is, a signal waveform due to radiation. Noise determination is performed using the regular signal waveform (a) as a reference and the characteristics of the noise pulse corresponding thereto as a determination reference.

  In FIG. 2, the waveforms of (b1-1) and (b1-2) are those in which the minimum peak value exceeds the reference level of reverse polarity, and these are determined by the b1 determination logic 411 to be reverse polarity wave height excessive. The The waveform of (b2-1) has a pulse width of a predetermined range or less, and (b2-2) has a pulse width of a predetermined range or more, and these are pulse widths determined by the b2 determination logic 412. Determined as abnormal. Both of the waveforms b1 and b2 are empirically high in the possibility of external noise entering the radiation detector 1 or a measurement unit, a transmission unit, a power input, and a ground line (not shown) from the outside. In addition, the case where it has the feature of both b2 and b1 is also considered.

  In the waveform (b3), the undershoot does not reach the reference level or less, and the b3 determination logic 413 determines that the undershoot is insufficient. The waveform b3 is unique to noise caused by a defect in the HV signal superimposition line of the radiation detector 1 regardless of the wave height.

  When radiation acts on the radiation sensor of the radiation detector 1, the signal pulse of the radiation sensor is superimposed on the bias voltage applied to the radiation detector 1 as a current change. This signal pulse current is DC cut by a capacitor, converted into a voltage pulse by a built-in preamplifier, and output from the radiation detector 1. Noises caused by defects in the HV signal superimposing line in the previous stage of the preamplifier include dark current discharge noise due to insulation failure, disconnection noise generated due to disconnection (half disconnection), and charge transfer noise generated due to insulation peeling. b3 is a waveform common to these, and is representative of noise in the radiation detector 1.

  Further, the waveform (b4) has a maximum peak value exceeding the signal waveform upper limit level, and is determined to be excessive by the b4 determination logic 414. This waveform b4 is a waveform peculiar to the electrostatic discharge light noise caused by the electrostatic discharge light generated by the rubbing and cracking of the insulator inside the radiation detector 1 entering the radiation sensor. A noise waveform such as b4 has the same shape as a regular signal, only the peak value is excessive, and does not have a characteristic of insufficient undershoot, and therefore has a clear difference from the waveform of b3.

  In the first embodiment, in the waveform analyzer 4, the determination order of the determination logics 411 to 414 of b1 to b4 is arbitrary, and each determination logic 411 to 414 is S / W even if realized by a circuit. It may be realized with. Moreover, the numerical value used for the output of the calculator 5 and the alarm determination, and the indication value displayed on the display 7 may be either the count rate m (current) or the radiation dose p (A). The display 7 displays at least one of the count rate m and the radiation dose p (A) output from the computing unit 5, and displays the noise mixing rate as necessary.

  Thus, according to the first embodiment, the undershoot shortage common to the dark current discharge noise, the disconnection noise noise, and the charge transfer noise caused by the defect of the HV signal superimposed line that cannot be identified by the conventional radiation measurement apparatus. Since the waveform (b3) can be identified and counted as a noise waveform, a highly reliable noise mixture rate can be obtained.

  In addition, since the noise mixing rate can be displayed on the display unit 7 as necessary, the cause of the increase in the indicated value (counting rate m or radiation dose p (A)) displayed on the display unit 7 is Whether it is due to an increase or due to the influence of noise can be determined accurately and quickly. From these things, a highly reliable radiation measuring apparatus is obtained.

Embodiment 2. FIG.
Since the configuration of the radiation measuring apparatus according to the second embodiment of the present invention is the same as that of the first embodiment, description will be made with reference to FIG. In the second embodiment, when the noise mixture rate is a predetermined value or more this time, it is confirmed whether or not the noise is transient noise, and the indication value (counting rate or radiation dose) due to transient noise is confirmed. It suppresses the rise.

  The computing unit 5 according to the second embodiment determines that there is noise intrusion when the noise mixture rate is equal to or higher than a predetermined value, checks the cumulative number of noise intrusions, and temporarily passes when the frequency is equal to or lower than the predetermined value. The radiation dose p (previous A) based on the count value A of the previous calculation cycle is output. When the number of times is greater than a predetermined value, it is determined that the noise is not transient noise, and the radiation dose p (current A) based on the count value A in the current calculation cycle is output.

  Next, operation | movement of the calculator 5 of the radiation measuring device which concerns on this Embodiment 2 is demonstrated using the flowchart of FIG. In FIG. 3, the numbers starting with S indicate the order (steps) of the arithmetic processing. First, in step 1 (S1), the calculator 5 reads the current count value A, the current noise mixture rate B ′ / A ′, and the radiation dose p (previous A) output of the previous calculation cycle from the memory 6. Subsequently, in step 2 (S2), the radiation dose p (current A) in the current calculation cycle is obtained based on the current count value A.

Next, in step 3 (S3), it is determined whether or not the current noise mixture rate B ′ / A ′ is greater than or equal to a predetermined value k set in advance. In S3, when the noise mixture rate is k or more this time (YES), the process proceeds to Step 4 (S4), and it is determined whether or not the noise intrusion cumulative number is equal to or less than a predetermined value u set in advance. In S4, if the cumulative number of noise intrusions is u or less (
YES), the process proceeds to step 5 (S5), and 1 is added to the cumulative number of noise intrusions.

  Then, it progresses to step 6 (S6), and the radiation dose output of the last calculation period acquired by S1 is employ | adopted as this output. Here, in S3, it is determined that the current noise mixture rate B ′ / A ′ is equal to or greater than the predetermined value k is due to transient noise.

  On the other hand, when the current noise mixture rate is smaller than k in S3 (NO), the process proceeds to step 7 (S7), and the radiation dose p (current A) based on the current count value A is adopted as the current output. Here, it is determined that the output this time is not influenced by transient noise but is due to the radiation dose.

In S4, when the cumulative noise intrusion count is larger than u (NO), the process proceeds to S7, and the radiation dose p (current A) based on the current count value A is adopted as the current output. here,
In S3, the current noise mixture rate B ′ / A ′ is equal to or greater than the predetermined value k is not a transient noise but a continuous noise caused by a failure of the radiation detector 1 or the like. Deciding.

After executing the processes of S6 and S7, the process proceeds to step 8 (S8), a predetermined calculation process is executed, and the process returns to S1. Note that the cumulative number of noise intrusions in S4 may be regarded as one for the duration after the current noise mixture rate becomes k or more in S3. Also, for noise determined to be transient noise, the record remaining in the memory 6 can be checked periodically, so that the noise resistance evaluation of the radiation measuring apparatus can be performed.

  According to the second embodiment, in addition to the same effect as the first embodiment, when the noise mixing rate is a predetermined value or more this time, whether or not this is transient noise is determined by the cumulative number of noise intrusions. When it is confirmed and it is determined that the noise is a transient noise, the radiation dose output of the previous calculation cycle is adopted, so that an increase in the instruction value due to the transient noise can be suppressed.

Embodiment 3 FIG.
FIG. 4 shows the configuration of the radiation measuring apparatus according to Embodiment 3 of the present invention. In FIG. 4, the same parts as those in FIG. In the first embodiment, the analog pulse waveform data output from the high-speed ADC 3 is not specifically defined in the determination order of the determination logics 411 to 414 of b1 to b4 in the noise determination logic 41 of the waveform analyzer 4. Noise was determined and OR processing was performed by the OR logic 415.

  In contrast, in the third embodiment, the noise determination logic 41 performs noise determination in the order of the b1 determination logic 411, the b2 determination logic 412, the b3 determination logic 413, and the b4 determination logic 414. It is counted as noise corresponding to the logic. That is, the determination results by the determination logics 411 to 414 for the b1 to b4 are counted by individual counters.

  Specifically, the pulses determined to be noise by the b1 determination logic 411 are counted by the reverse polarity wave height excess counter 416 (hereinafter, b1 counter 416). Further, the pulse determined to be noise by the b2 determination logic 412 is counted by a pulse width abnormality counter 417 (hereinafter, b2 counter 417). Similarly, a pulse determined to be noise by the b3 determination logic 413 is counted by an undershoot shortage counter 418 (hereinafter referred to as a b3 counter 418), and a pulse determined to be noise by the b4 determination logic 414 is counted as a pulse height counter 419 ( Hereinafter, it counts with b4 counter 419). Note that the order of noise determination by the determination logics 411 to 414 of b1 to b4 may be b2, b1, b3, and b4.

  The count values B1, B2, B3, and B4 output from the respective counters 416 to 419 of b1 to b4 are input to the computing unit 5 at regular intervals. The computing unit 5 obtains a moving average value of a predetermined number of computation periods for the inputted count values B1, B2, B3, and B4, and sets them as B1 ′, B2 ′, B3 ′, and B4 ′. The individual ratios, that is, individual noise mixing rates B1 ′ / A, B2 ′ / A, B3 ′ / A, and B4 ′ / A are obtained.

  Further, in the third embodiment, the display 7 displays the characteristics of the noise waveform, the individual noise mixture rate, the estimated noise occurrence location, as necessary, in addition to the indicated value (counting rate or radiation dose) and the noise mixing rate. The cause of noise can be displayed.

A display example on the display 7 of the radiation measuring apparatus according to the third embodiment is shown in FIG. In the example illustrated in FIG. 5, an instruction value (200 cpm), a noise mixing rate (50%), a noise characteristic, an individual noise mixing rate, a noise location, and a noise factor are displayed. When the noise characteristics are “undershoot shortage” and “wave height excessive”, the noise portion is displayed as “radiation detector”. Also, as HV signal line insulation failure (dark current discharge noise), HV signal line disconnection (contact disconnection noise), and HV signal line insulator peeling (charge transfer noise) are displayed as noise factors of “undershoot shortage”. In addition, as a noise factor of “excessive wave height”, it is displayed that the insulator is rubbed or cracked (electrostatic discharge light noise).

  In addition, when the noise characteristics are `` reverse polarity wave height excess '' and `` pulse width abnormality '', the noise location is displayed as `` radiation detector, measurement unit, transmission unit, power input, ground line '', and the noise factor is `` “External noise” is displayed.

  In conventional radiation measurement devices, the display did not display the characteristics of the noise waveform, the estimated noise occurrence location, factors, etc. in correspondence with the indicated values. It was impossible to immediately determine whether it was due to noise, and it took time to investigate the cause of the increase in the indicated value.

  On the other hand, according to the third embodiment, in the noise determination logic 41 of the waveform analyzer 4, the noise determination results obtained by the determination logics 411 to 414 of b1 to b4 are displayed by the counters 416 to 419 of b1 to b4. The individual noise mixing rate is obtained by counting individually, and the noise occurrence location and factors estimated from the individual noise mixing rate and the characteristics of the noise waveform are displayed on the display 7. It is possible to accurately and quickly determine whether the noise is due to an increase in radiation or the influence of noise, and whether the noise is due to abnormality of the radiation detector 1 or external noise.

  Thereby, in the case of abnormality of the radiation detector 1, it is possible to quickly deal with equipment replacement and the like, so it is possible to recover in a short time and to shorten the missing measurement time. In addition, since the noise factor corresponding to the characteristics of the noise waveform is displayed, the investigation of the essential cause after the restoration can be performed efficiently, and a radiation measuring apparatus with high reliability and maintainability can be obtained.

Embodiment 4 FIG.
FIG. 6 shows the configuration of a radiation measuring apparatus according to Embodiment 4 of the present invention. In FIG. 6, the same parts as those in FIG. In the third embodiment, the noise determination logic 41 of the waveform analyzer 4 performs noise determination in the order of determination logics b1, b2, b3, and b4 (or b2, b1, b3, and b4), and determines each noise. The results were counted individually by the counters 416 to 419 for b1 to b4.

  On the other hand, in the fourth embodiment, as shown in FIG. 6, noise determination by the determination logics 411 to 414 of b1 to b4 is performed in parallel, and noise is determined by a plurality of determination logics. The determination logic with a high priority is used. The priorities of the determination logics 411 to 414 are b4 determination logic 414, b3 determination logic 413, b2 determination logic 412, and b1 determination logic 411 (that is, b4> b3> b2> b1) from the highest. Note that the priority order may be interchanged between the b2 determination logic 412 and the b1 determination logic 411 (that is, b4> b3> b1> b2).

  The determination results of the determination logics 411 to 414 are checked in the order of b4, b3, b2, and b1 (or b4, b3, b1, and b2) in the OR logic 415, and the noise waveform is represented by the first corresponding one. Become. Each noise determination result is individually counted by each of the counters 416 to 419 b1 to b4 as in the third embodiment.

  The reason why the order of checking the noise determination results by the determination logics 411 to 414 is b4, b3, b2, b1 (or b4, b3, b1, b2) in the fourth embodiment will be described. As described in the first embodiment, noise is roughly classified into internal noise related to equipment failure and external noise (mainly b1 and b2) entering from the outside including the power supply line.

  Empirically, when typical b3 and b4 exist as internal noise, it is clear that the internal noise is related to equipment failure without being mixed with b1 and b2. On the other hand, when b1 and b2 exist, they are combined to generate b3 and b4, which may be mixed. Therefore, accurate counting can be performed by preferentially checking b4 (or b3) whose cause is clear.

  Also in the fourth embodiment, as in the third embodiment, the display unit 7 displays the characteristics of the noise waveform as well as the indication value (counting rate or radiation dose) and the noise mixing rate, as necessary. It is possible to display a noise mixing rate, an estimated noise occurrence location, a noise factor, and the like.

  According to the fourth embodiment, the same effect as in the third embodiment can be obtained, and further, the calculation speed can be increased more than in the third embodiment.

Embodiment 5 FIG.
FIG. 7 shows the configuration of the radiation measuring apparatus according to the fifth embodiment of the present invention. In FIG. 7, the same parts as those in FIG. The radiation measuring apparatus according to the fifth embodiment has a configuration similar to that of the first embodiment (FIG. 1), an up / down counter 45 having an addition input 451 and a subtraction input 452 in the waveform analyzer 4, a frequency A synthesizer (circuit) 46 and an integration controller (circuit) 47 are provided.

  In the first embodiment, the digital pulse a satisfying a predetermined wave height condition is output from the wave height determination logic 42 of the waveform analyzer 4, and the current count value A, which is counted at a fixed period, is calculated by the calculator 5 with a standard deviation. The calculation was made to be constant, and the count rate m (current) was obtained.

  On the other hand, in the fifth embodiment, the digital pulse b of the noise waveform counted by the first counter 43 is input to the addition input 451 of the up / down counter 45 with predetermined weighting, and is added and counted. Further, a feedback pulse (negative feedback pulse) of a repetition frequency corresponding to the integrated value M is input to the subtraction input 452 of the up / down counter 45 with a predetermined weighting, and is subjected to subtraction counting.

The frequency synthesizer 46 receives the integrated value M from the calculator 5, inputs the clock pulse of the calculator 5 based on the integrated value M, and generates a feedback pulse by frequency division and frequency synthesis. The integration controller 47 performs weighting of 2 ^α = 2 ² = 4 when the up / down counter 45 counts, for example, when σ = 0.026, based on Expression 5 shown in the first embodiment, When σ = 0.052, weighting of 2 ^α = 2 ⁴ = 16 is performed.

The computing unit 5 receives the integrated value M output from the up / down counter 45, and based on the integrated value M, obtains the count rate m by the equation 3 shown in the first embodiment, and the radiation dose p (M ) Expression 31 below is a modification of Expression 3, and shows the relationship between the integrated value M and the count rate m when the standard deviation σ and the constant γ = 2σ ² are set.
M = (1 / γ) ln (m) (Equation 31)

The computing unit 5 calculates the radiation dose p (current M) based on the current integrated value M as a normal output, and calculates the radiation dose p (current A) based on the current count value A as a backup output. Normally, the normal dose of radiation dose p (current M) is output, and if the noise contamination rate is greater than or equal to a predetermined value, it is determined that noise has entered (influenced) and the cumulative number of noise intrusions so far is confirmed. Then, the radiation dose p (previous M) in the previous calculation cycle is output until the number of times reaches a predetermined value. Note that the cumulative number of noise intrusions is the number of times that the noise mixture rate is greater than or equal to a predetermined value and is determined to be affected by noise.

  Further, when it is determined that there is no influence of noise within a predetermined number of calculation cycles, the radiation dose p (current time) until the radiation dose p (current time M) returns to a level equivalent to the radiation dose p (current time A). A) is output. Thereafter, it is confirmed that the radiation dose p (current M) has returned to the same level as the radiation dose p (current A), and the radiation dose p (current M) is output.

  The operation of the computing unit 5 in the radiation measuring apparatus according to the fifth embodiment will be described using the flowchart of FIG. First, in step 11 (S11), the computing unit 5 reads the current count value A, the current integrated value M, the current noise mixture rate B ′ / A ′, and the radiation dose p (previous M) in the previous calculation cycle from the memory 6. . Subsequently, in step 12 (S12), a radiation dose p (current M) in the current calculation cycle is obtained based on the current integrated value M.

Next, in step 13 (S13), it is determined whether or not the current noise mixture rate B ′ / A ′ is greater than or equal to a predetermined value k set in advance. In S13, when the noise mixture rate is k or more this time (YES), the process proceeds to Step 14 (S14), and it is determined whether or not the noise intrusion cumulative number is equal to or less than a predetermined value u set in advance. In S14, the cumulative noise intrusion count is u
In the following case (YES), the process proceeds to step 15 (S15), and 1 is added to the cumulative number of noise intrusions.

  Then, it progresses to step 16 (S16), and it is determined whether the noise penetration | invasion continuation frequency is below the predetermined value w set beforehand. The noise intrusion continuation count is the number of times that the period determined to have an influence of noise continues for a predetermined period. In S16, when the noise intrusion continuation count is equal to or less than w (YES), the process proceeds to step 17 (S17), and 1 is added to the noise intrusion continuation count. Subsequently, in step 18 (S18), the radiation dose p (previous M) of the previous calculation cycle acquired in S1 is adopted as the current output. Here, in S13, it is determined that the current noise mixture rate B ′ / A ′ is equal to or greater than the predetermined value k is due to transient noise and is not reflected in the indicated value.

  On the other hand, if the current noise mixture rate is smaller than k in S13 (NO), that is, if it is determined that there is no influence of noise, the process proceeds to step 19 (S19), and it is confirmed whether or not the noise intrusion continuation count is 1 or more. In S19, when the noise intrusion continuation count is 1 or more (YES), there is a possibility that the count rate of the regular high speed operation may not be restored due to the influence of noise intrusion, so the current count value A is set in step 20 (S20). The radiation dose p (current A) is obtained by a counting rate calculation based on this (backup).

  Subsequently, in step 21 (S21), it is determined whether or not the radiation dose p (current M) / radiation dose p (current A) is equal to or less than a predetermined value (here, 1 + 3σ). If it is larger than the predetermined value (NO), it is determined that the normal high-speed operation count rate has not returned due to noise intrusion, and the process proceeds to step 22 (S22). The quantity p (this time A) is adopted.

  On the other hand, in S21, when the radiation dose p (current M) / radiation dose p (current A) is equal to or smaller than a predetermined value (YES), it is determined that the count rate of the regular high-speed operation is restored, and step 23 (S23). Proceed to to reset the noise intrusion continuation count. Further, the process proceeds to step 24 (S24), and the normal dose of radiation dose p (current M) is adopted as the current output.

In S14, when the cumulative noise intrusion count is larger than u (NO), and S16
If the noise intrusion continuation count is larger than w (NO), it is determined that the noise is not transient noise, and the process proceeds to S24, where the radiation dose p (current M), which is a normal output, is adopted. After executing the processes of S18 and S24, the process proceeds to step 25 (S25), a predetermined calculation process is executed, and the process returns to S11.

  Note that the predetermined values k, u, and w described in the flowchart shown in FIG. 8 are arbitrarily determined by a facility (apparatus) administrator or the like. At that time, when it is necessary to strictly manage depending on the place where the radiation measuring apparatus is installed, or when it is necessary to take immediate measures against the radiation dose increase or noise generation, the predetermined values k, u, It is considered to set w to a smaller value.

  According to the fifth embodiment, in addition to the same effects as those of the first embodiment, the waveform analyzer 4 causes the count rate m and the integrated value M to be constant with the standard deviation σ in the relationship of the above equation 31. By providing the integration controller 47 for balancing, the load on the computing unit 5 can be reduced compared to the first embodiment, and the integrated value M can be measured continuously. Thereby, counting down can be suppressed with respect to a high count rate, and a highly accurate calculation result is obtained. Furthermore, if the count rate of the regular high-speed operation has not been restored due to the influence of noise intrusion, the count rate calculation based on the current count value A is substituted until the restoration, so the effect of noise is reduced. Can be suppressed.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  The present invention can be used as a radiation measurement device used for monitoring the radiation dose in a nuclear reactor facility, a spent fuel reprocessing facility, or the like.

1 radiation detector, 2 pulse amplifier, 3 high-speed AD capacitor, 4 waveform analyzer,
5 arithmetic unit, 6 memory, 7 display unit, 41 noise judgment logic,
42 wave height a determination logic, 43 first counter, 44 second counter,
45 up / down counter, 46 frequency synthesizer, 47 integration controller,
411 reverse polarity wave height excessive (b1) determination logic,
412 Pulse width abnormality (b2) determination logic,
413 Undershoot shortage (b3) determination logic,
414 Wave height excess (b4) decision logic, 415 OR logic,
416 reverse polarity wave height excess (b1) counter, 417 pulse width error (b2) counter,
418 Undershoot shortage (b3) counter, 419 Wave height excess (b4) counter, 451 addition input, 452 subtraction input.

Claims (13)

Radiation detection means for detecting radiation and outputting analog pulses;
Waveform measuring means for inputting the analog pulse, measuring a waveform for a pulse height level or higher and outputting waveform data;
Waveform analysis means for analyzing the waveform data input from the waveform measurement means and outputting a count value A for counting a pulse a of a waveform that satisfies a predetermined peak height range condition and a count value B for counting a pulse b of a noise waveform;
The count value A and the count value B are input at regular intervals, the count rate m and the radiation dose p (A) based on the count value A are obtained, and a moving average of a predetermined number of calculation cycles of the count value A and the count value B Calculating means for obtaining the noise mixing rate B ′ / A ′ from the values A ′ and B ′;
In addition to displaying at least one of the counting rate m and the radiation dose p (A) output from the computing unit, the display unit displays a noise mixing rate as necessary.
The waveform analysis means includes noise determination means for identifying a waveform having a characteristic of a noise waveform from the input waveform data, and the noise determination means detects a portion where the wave height deviates from a predetermined level to a reverse polarity. A reverse polarity wave height excess judging means for identifying a waveform having a pulse width abnormality judging means for identifying a waveform whose pulse width deviates from a predetermined range, and a waveform in which an undershoot at the falling edge of the pulse does not reach a predetermined range of a reverse polarity look including the crest excessively determination means for identifying and undershoot shortage determination unit identifies a waveform wave height exceeds a predetermined level,
The waveform analysis means individually detects pulses of the waveform determined as noise by the respective determination means of the reverse polarity wave height excess determination means, the pulse width abnormality determination means, the undershoot shortage determination means, and the wave height excess determination means. Output the counted values B1, B2, B3, B4,
The calculation means calculates the individual noise mixture rate from A ′ and B1 ′, B2 ′, B3 ′, and B4 ′, which are moving average values of a predetermined number of calculation cycles of the count value A and the count values B1, B2, B3, and B4. B1 '/ A', B2 '/ A', B3 '/ A', B4 '/ A' is calculated | required, The radiation measuring apparatus characterized by the above-mentioned.   The waveform measuring means converts the analog pulse to voltage data arranged in a time series in a period in which a predetermined time from when the voltage data becomes equal to or higher than the trigger level and a predetermined time immediately before the voltage reaches the trigger level. The radiation measurement apparatus according to claim 1, wherein the radiation data is output as waveform data of   The radiation according to claim 1 or 2, wherein the calculation means outputs an alarm when the radiation dose p (A) is a predetermined value or more, and the display means displays the alarm. measuring device. The noise determination means performs the determination in the order of the reverse polarity wave height excess determination means, the pulse width abnormality determination means, the undershoot shortage determination means, and the wave height excess determination means, and corresponds to the determination means that first determined noise. The radiation measuring apparatus according to any one of claims 1 to 3, wherein the radiation measuring apparatus counts as noise. The noise determination unit performs the determination in the order of the pulse width abnormality determination unit, the reverse polarity wave height excess determination unit, the undershoot shortage determination unit, and the wave height excess determination unit, and corresponds to the determination unit that first determines noise. The radiation measuring apparatus according to any one of claims 1 to 3, wherein the radiation measuring apparatus counts as noise. The noise determination means performs determination by the reverse polarity wave height excess determination means, the pulse width abnormality determination means, the undershoot shortage determination means, and the wave height excess determination means in parallel, and is determined as noise in a plurality of determination means. If it is, the radiation measurement apparatus according to any one of claims 1 to 3, wherein the determination by a determination unit having a high priority is adopted. Priority of each judging means, the wave height too determining means from the higher, the undershoot shortage determination unit, the pulse width abnormality determining means, according to claim 6, wherein the a polarity opposite crest excessive determining means Radiation measurement device. Priority of each judging means, the wave height too determining means from the higher, the undershoot shortage determination unit, wherein the reverse polarity crest excessive determining means, according to claim 6, characterized in that the said pulse width abnormality determining means Radiation measurement device. The calculation means estimates the location and factor of noise generation from the characteristics of the waveform determined as noise by each of the determination means, and the display means calculates the noise mixing rate, individual noise mixing rate, noise waveform characteristics, and generation. radiation measuring apparatus as claimed in any one of claims 8, characterized in that to be displayed according points and factors required respectively. The arithmetic means is the noise detected by the reverse polarity wave height excess determination means and the pulse width abnormality determination means, and the occurrence location is the radiation detection means, radiation measurement means, transmission means, power input means, and ground line. The radiation measurement apparatus according to claim 9 , wherein the radiation measurement apparatus estimates that the cause is external noise. Regarding the noise determined by the undershoot shortage determining means, the calculating means is the radiation detecting means, and the cause is any of insulation failure, disconnection, and insulation peeling of the HV signal superimposed line. The radiation measuring apparatus according to claim 9 , wherein the radiation measuring apparatus is estimated. The calculation means estimates that the noise determined by the wave height excess determination means is generated by the radiation detection means, and that the factor is rubbing or cracking of an insulator inside the radiation detection means. The radiation measuring apparatus according to claim 9 . The calculation means confirms the cumulative number of noise intrusions when the noise mixture rate is equal to or higher than a predetermined value. outputs p (previous a), is greater than a predetermined value, claim from claim 1, characterized in that for outputting a radiation dose p based on the count value a of the current operation cycle (time a) 12 The radiation measuring device according to any one of the above.

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