JP6037670B2 - Radiation measurement equipment - Google Patents

Description

  The present invention relates to a radiation measuring apparatus constituting a radiation monitoring apparatus used for radiation management in facilities such as nuclear power plants and nuclear fuel related facilities.

  Generally, the radiation measuring apparatus processes a pulsed radiation detection signal output from a radiation detector, and calculates a radiation dose rate or a radioactive substance concentration from a pulse count rate which is an input repetition frequency.

  Since the output of the radiation detector is a minute pulse, it is a problem to issue an erroneous count due to noise mixing and a false alarm associated therewith. For this reason, in the radiation measurement device, the output signal from the radiation detector is amplified and shaped by an electric circuit, and the signal having a frequency significantly different from the time constant of the detector is subjected to processing for removing noise by the function of the band pass filter. Yes.

  Furthermore, when using a pulse height discriminator, a pulse above a certain peak value (this peak value is regarded as the peak height discrimination level) is regarded as a true radiation detection signal, and signals that do not reach the peak height discrimination level are eliminated as noise. Has been done. If the wave height of the input signal is greater than the wave height discrimination level, the wave height discriminator outputs a logic pulse. For this reason, a signal smaller than the wave height discrimination level is removed as noise. By setting the wave height discrimination level to be significantly higher than the peak value of the observed noise, it is possible to eliminate noise by wave height discrimination. In general, since the output pulse height of the radiation detector is proportional to the energy of the radiation, the upper and lower limits of the wave height are set according to the energy range of the radiation to be measured, and the lower and upper limits of the pulse height discrimination level are set. A method of measuring only a range of pulses is also used. When the upper and lower limits of the wave height discrimination level are set, a huge pulse generated by noise can be removed (see, for example, Patent Document 1).

  In general, the pulse waveform output from the radiation detector has a unique shape for each detector. Therefore, this property is used to determine the authenticity of the input pulse from the waveform information such as the pulse width. (For example, refer to Patent Document 1).

  Of the noise input to the radiation measurement apparatus, unipolar noise can be almost removed by the above processing, but noise oscillating in both positive and negative polarities cannot be removed. When the noise is oscillating, since a waveform similar to a normal pulse is periodically input, it can be determined from the radiation measurement apparatus that a pulse exceeding the pulse height discrimination level is periodically input. For this reason, as a method for removing vibration noise, a method is provided in which a pulse height discrimination level is provided on the side opposite to the normal pulse to detect and remove signal vibration (see, for example, Patent Document 2).

JP 2008-215907 A JP-A-1-3572

  The amplifier that amplifies the output pulse of the radiation detector becomes a low-pass / high-pass filter due to its frequency characteristics, and can remove a signal having a frequency greatly different from the frequency of the normal pulse waveform output from the radiation detector. However, noise having a frequency close to that of a normal signal cannot be removed using only the filter. For example, as shown in FIG. 1, the waveforms b and c in FIG. 1 can be removed from the normal signal having the waveform a in FIG. However, if attention is paid only to the positive electrode side, the waveform d in FIG. 9 has almost the same pulse width as the normal pulse and cannot be removed.

  In addition, since the normal pulse output from the radiation detector is unipolar (in this case, positive polarity), the pulse height discrimination level should be set on the negative electrode side as in Patent Documents 1 and 2 for vibration noise. However, if the vibration noise is offset as shown in FIG. 2, it cannot be removed because it does not fall below the wave height discrimination level on the negative electrode side, resulting in erroneous counting.

  Further, when noise that vibrates in both polarities is superimposed on a normal signal, the method of Patent Document 2 removes all signals after vibration detection, so that the normal signal is also removed at the same time, causing counting down. was there.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a radiation measuring apparatus capable of accurately removing radiation components and accurately performing radiation measurement.

The radiation measuring apparatus according to the present invention includes a first pulse height discriminating means for inputting an analog signal pulse output from a radiation detector, discriminating and outputting a pulse satisfying a predetermined wave height condition, and an analog signal pulse. Waveform discriminating means for discriminating and outputting pulses satisfying a predetermined waveform condition; pulse waveform judging means for judging whether or not the waveform of the analog signal pulse is normal based on outputs of the first wave height discriminating means and the waveform discriminating means; The signal synthesis means for outputting the analog signal pulse obtained by synthesizing the analog signal pulse and the pulse obtained by delaying the analog signal pulse for a certain time, and the output signal of the first wave height discrimination means is the analog output from the radiation detector. generated at a timing time delay comparable to the predetermined time from the generation timing of the signal pulses, and a long time continuous than the predetermined time A gate generating means for generating a gate signal with that signal, of the output signal combining means of the section to continue the gate signal, and a second wave height discriminator for outputting the discriminated predetermined height condition is satisfied pulse, the A double count removing means for removing a double count generated by the wave height discriminating means, and a noise removing means for removing noise based on the output of the pulse waveform determining means and the output of the double count removing means. The radiation detected by the radiation detector is measured based on the number of output pulses.

  The radiation measuring apparatus according to the present invention combines an analog signal pulse and a pulse obtained by delaying the analog signal pulse for a predetermined time, and further combines a gate signal that lasts longer than the predetermined delay time, Among the pulses in the section, the pulses satisfying the predetermined peak height are discriminated and output, and the double count is removed, so that the noise component can be removed accurately, and as a result, the radiation measurement is performed accurately. be able to.

It is explanatory drawing which shows the waveform of a normal signal and a noise signal. It is explanatory drawing which shows the case where vibration noise is offset. It is a block diagram which shows the radiation measuring device by Embodiment 1 of this invention. It is a timing chart which shows the vibration noise removal of the radiation measuring device by Embodiment 1 of this invention. It is a timing chart which shows the operation | movement which removes the vibration noise superimposed on the normal pulse of the radiation measuring device by Embodiment 1 of this invention. It is a flowchart which shows the noise removal operation | movement of the radiation measuring device by Embodiment 1 of this invention. It is a block diagram which shows the radiation measuring device by Embodiment 2 of this invention. It is a timing chart which shows the vibration noise removal of the radiation measuring device by Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 3 is a block diagram showing the radiation measuring apparatus according to Embodiment 1 of the present invention.
The illustrated radiation measurement apparatus includes a radiation detector 1, an amplifier 2, a waveform determination unit 3, a vibration noise removal unit 4, a noise removal circuit 5, a rate meter circuit 6, and an engineering value calculation circuit 7. The radiation detector 1 is a detector that detects radiation and outputs the value as an analog signal pulse. The amplifier 2 is a circuit that amplifies the output from the radiation detector 1. The waveform determination unit 3 is a block for determining whether or not the waveform is normal with respect to the output of the amplifier 2, and includes a first wave height discrimination circuit 31, a waveform discrimination circuit 32, and a pulse waveform determination circuit 33. The first wave height discriminating circuit 31 is a first wave height discriminating means that receives the analog signal pulse amplified by the amplifier 2 and discriminates and outputs a pulse that satisfies a predetermined wave height condition. The waveform discriminating circuit 32 is a waveform discriminating means that receives the analog signal pulse amplified by the amplifier 2 and discriminates and outputs a pulse satisfying a predetermined waveform condition. The pulse waveform determination circuit 33 is a pulse waveform determination unit that performs an AND operation on the output of the first wave height discrimination circuit 31 and the output of the waveform discrimination circuit 32 to determine whether or not the waveform of the analog signal pulse is normal.

  The vibration noise removing unit 4 is a block that removes vibration noise from the output of the amplifier 2, and includes a delay circuit 41, a synthesis circuit 42, a gate generation circuit 43, a synthesis gate circuit 44, a second wave height discrimination circuit 45, a double circuit. A count removal circuit 46 is provided. The delay circuit 41 is a circuit that receives the output of the amplifier 2, delays it for a predetermined time, and outputs it to the synthesis circuit 42. The synthesizing circuit 42 is a signal synthesizing unit that outputs an analog signal obtained by synthesizing the output of the amplifier 2 and the output of the delay circuit 41. The gate generation circuit 43 is a gate generation unit that outputs a gate signal having a time longer than the delay time of the delay circuit 41 (preferably about twice as long) based on the output of the first wave height discrimination circuit 31. The synthesis gate circuit 44 is a circuit that synthesizes and outputs the gate signal of the gate generation circuit 43 with respect to the output of the synthesis circuit 42. The second wave height discrimination circuit 45 is a circuit for determining whether the analog signal output from the synthesis gate circuit 44 is equal to or higher than the wave height discrimination level based on a preset wave height discrimination level 2. The 2nd wave height discrimination means is comprised. The double count removal circuit 46 is double count removal means for removing double counts generated by the second wave height discrimination circuit 45.

  The noise removal circuit 5 is a noise removal unit that performs an AND operation on the output of the waveform determination unit 3 and the output of the vibration noise removal unit 4 to remove noise. The rate meter circuit 6 is a circuit that calculates a count rate (a count value divided by a measurement time), which is a count per unit time, for the pulses output from the noise removal circuit 5. The engineering value calculation circuit 7 is a circuit that calculates an engineering value by multiplying a current counting rate by a conversion factor from a counting rate previously determined in a calibration test to a dose rate or a radioactive concentration.

  4 and 5 are timing charts of each part conceptually showing the noise removing operation in the vibration noise removing unit 4 of the radiation measuring apparatus. (A) to (g) in FIGS. 4 and 5 correspond to the output signals (a) to (g) in FIG. 3, respectively. That is, (a) is an analog signal output from the amplifier 2, (b) is an analog signal output from the delay circuit 41, (c) is an analog signal output from the synthesis circuit 42, and (d) is , A logic signal output from the gate generation circuit 43, (e) an analog signal output from the synthesis gate circuit 44, (f) a logic signal output from the second wave height discrimination circuit 45, and (g) , Logic signals output from the double count removal circuit 46 are shown. 4 illustrates the operation of the vibration noise removing unit 4 in the case of a normal pulse and vibration noise, and FIG. 5 illustrates the case of a normal pulse on which vibration noise is superimposed.

  Here, the normal pulse is an analog signal output as a result of detection of radiation by the radiation detector 1 as shown in the waveform a of FIG. 1, and is a pulse having a single unipolar peak, The pulse width is determined by the type of the radiation detector 1 and the circuit constant of the amplifier 2. In addition, the vibration noise is a wave having both positive and negative polarities that is continued a plurality of times as shown by the waveform d in FIG. Although the amplitude of noise fluctuates, in practice, the difference in amplitude between adjacent waves is almost negligible. Of particular concern among vibration noises is the case where the half-period of vibration is close to that of a normal pulse, that is, the frequency is similar to that of a normal pulse, and the amplitude is close to the peak value of the normal pulse. Hereinafter, the vibration wave having such a waveform is referred to as vibration noise.

  In FIG. 3, an analog signal pulse obtained as a result of detection of radiation by the radiation detector 1 is input to the amplifier 2. The amplifier 2 amplifies the analog signal output from the radiation detector 1 and outputs it. The output signal of the amplifier 2 is branched into two, one is input to the waveform determination unit 3 in order to remove a greatly different waveform from the normal pulse, and the other is vibration noise to remove the vibration component in the input signal. Input to the removal unit 4.

  The signal input to the waveform determination unit 3 is further branched into two and input to the first wave height discrimination circuit 31 and the waveform discrimination circuit 32, respectively. The first wave height discriminating circuit 31 is a single channel wave height analyzer, and outputs a High signal as a logic value when the peak value of the input pulse is within a predetermined range, and the peak value of the input pulse is outside the predetermined range. In this case, a Low signal is output as a logic value. When the pulse width of the input pulse signal is within a predetermined range, the waveform discrimination circuit 32 outputs a High signal having a predetermined time width as a logic value, and when the pulse width of the input pulse is outside the predetermined range, A Low signal is output as a logic value. Here, the predetermined time width is a time width of about twice the width of the normal pulse as shown by the waveform a in FIG.

  Output signals from the first wave height discriminating circuit 31 and the waveform discriminating circuit 32 are input to the pulse waveform determining circuit 33, and an AND operation between them is performed. That is, when the peak value is within the energy range of the radiation to be measured and the pulse width is within the range of the normal pulse, it is determined as a normal pulse. When it is determined as a normal pulse, the pulse waveform determination circuit 33 outputs a High signal as a logic value, and when it is not determined as a normal pulse, it outputs a Low signal as a logic value. This logic value becomes the processing result of the waveform determination unit 3.

The signal input to the vibration noise removing unit 4 is further branched into two, one is input to the synthesis circuit 42 as it is, and the other is input to the synthesis circuit 42 via the delay circuit 41. The delay circuit 41 delays the input analog signal by a predetermined time width and outputs it. Here, the signal delay time W ₁ of the delay circuit 41 is set to the pulse width of the normal pulse. Since the combining circuit 42 outputs a combined signal of two input signals, as shown in the signal sequence (c) of FIG. 4, when a normal waveform is input, two peaks are arranged.

The gate generation circuit 43 delays the logic signal from the first wave height discriminating circuit 31 by the time W _{1 and} outputs it over the time width W ₂ . Here, W ₂ is set to be slightly less than twice W ₁ . When it exceeds 2 times, the gate signal continues, so that it is slightly below 2 times. The synthesis gate circuit 44 outputs a signal input from the synthesis circuit 42 only when the output signal of the gate generation circuit 43 is ON. Analog Thus, the synthetic gate circuit 44, as shown in FIG. 4 (e) (1), the waveform of the delay time W ₁ interval is removed in a composite waveform (c), delayed by the delay circuit 41 Only the signal is output. Thus, when a normal pulse is output from the radiation detector 1, the output of the synthesis gate circuit 44 is a unipolar pulse.

  The second wave height discriminating circuit 45 outputs a high signal as a logic value when the wave height value is within a predetermined range with respect to the analog signal output from the synthesis gate circuit 44, and the wave height value is out of the predetermined range. In some cases, a Low signal is output as a logic value. As shown in FIG. 4F, when a normal pulse is output from the radiation detector 1, only one High signal as a logic value is output.

The double count removal circuit 46 receives the logic value output from the second wave height discrimination circuit 45. If the High signal is input as a logic value, as shown in FIG. 4 (g) (1), regardless of the width of the input High signal, and outputs a High signal time width _{W 3.} Here, _{W 3} is set to 2 times the _{W 1.} Note that double counting removing circuit 46, when outputting a High signal time width W ₃ is entered High signal, by leaving to not accept the next High signal, output from the second wave height discriminator circuit 45 It is possible to eliminate a double count that erroneously counts when two logic signals are combined into one and there are two normal pulses. This logic signal becomes the processing result of the vibration noise removing unit 4.
Here, as shown in (a) and (g) of FIG. 4 (1), the number of signals of the logic value High output from the vibration noise removing unit 4 is the result of the radiation detector 1 detecting the radiation. It is equal to the number of normal analog signal pulses obtained.

The processing results of the waveform determination unit 3 and the vibration noise removal unit 4 are input to the noise removal circuit 5. The noise removal circuit 5 performs an AND operation on the two input signals. When the waveform determination unit 3 determines that the peak value and the pulse width are within the range of the normal waveform, the waveform determination unit 3 outputs a High signal as a logic value, and thus the number of logic signals output from the noise removal circuit 5 Is equal to the number of normal analog signal pulses obtained as a result of the radiation detector 1 detecting the radiation.
The logic value High signal output from the noise removal circuit 5 is input to the rate meter circuit 6, and after calculating the count rate, an engineering value such as a radiation dose rate or radioactivity concentration is further calculated by the engineering value calculation circuit 7. Is output.

Next, an operation when a normal pulse is not output from the radiation detector 1 and the vibration noise shown in FIG. 4 (2) (a) is input to the amplifier 2 will be described.
The amplifier 2 amplifies the mixed vibration noise and outputs it. The output signal of the amplifier 2 is branched into two, one is input to the waveform determination unit 3 in order to remove a greatly different waveform from the normal pulse, and the other is vibration noise to remove the vibration component in the input signal. Input to the removal unit 4.

  The signal input to the waveform determination unit 3 is further branched into two and input to the first wave height discrimination circuit 31 and the waveform discrimination circuit 32, respectively. Since the amplitude of the vibration noise is within a predetermined range, the first wave height discrimination circuit 31 outputs a High signal as a logic value. Further, since the half cycle of the vibration noise has a time width close to that of a normal pulse, the waveform discrimination circuit 32 determines that the pulse width of the input pulse is within a predetermined range and outputs a High signal as a logic value. Output signals from the first wave height discriminating circuit 31 and the waveform discriminating circuit 32 are input to the pulse waveform determining circuit 33, and as a result of performing an AND operation on both, it is determined as a normal pulse, and a High signal is output as a logic value. . Therefore, the processing result of the waveform determination unit 3 is a High signal as a logic value.

The signal input to the vibration noise removing unit 4 is further branched into two, one is input to the synthesis circuit 42 as it is, and the other is input to the synthesis circuit 42 via the delay circuit 41. The delay circuit 41 delays the input analog signal by a predetermined time width and outputs it. Here, the signal delay time W ₁ of the delay circuit 41 is set to the pulse width of the normal pulse. The combining circuit 42 outputs a combined signal of two input signals. The two input signals (a) in FIG. 4 (2) and (b) in FIG. 4 (2) are sine waves that are shifted from each other by a half wavelength. Since these can be regarded, the amplitude components of the positive electrode side and the negative electrode side cancel each other, and the output becomes zero. However, as shown in signal (c) in FIG. 4 (2), for the region of the time width W ₁ from the start of the vibration noise, remain without being canceled waveform of the input vibration noise, the end of the vibration noise from about areas time width W _1, the waveform of the end portion of the delayed oscillation noise is left as it is without being canceled.

The output signal of the synthesis circuit 42 is input to the synthesis gate circuit 44. The gate generation circuit 43 delays the output signal of the first wave height discrimination circuit 31 by the time W _{1 and} outputs it over the width W ₂ . Here, W ₂ is set to be slightly less than twice W ₁ . If W ₂ exceeds twice the _{W 1,} the gate signal is continuous, _{W 2} is kept set to be _{W 1 ≦ W 2 <2W 1} .
The synthesis gate circuit 44 outputs a signal input from the synthesis circuit 42 only when the output signal of the gate generation circuit 43 is ON. Analog Thus, the synthetic gate circuit 44, as shown in FIG. 4 (e) (1), the waveform of the delay time W ₁ interval is removed in a composite waveform (c), delayed by the delay circuit 41 Only the signal is output. As a result, the waveform of the vibration noise remaining in the region of the time width W ₁ from the start of the vibration noise is removed from the signal (c) in FIG. 4 (2), and is shown in FIG. 4 (2) (e). Similarly, the outputs other than the negative side output remaining in the region of the time width W ₁ from the end of the vibration noise are zero.
The second wave height discriminating circuit 45 outputs a high signal as a logic value when the wave height value is within a predetermined range with respect to the analog signal output from the synthesis gate circuit 44, and the wave height value is out of the predetermined range. In some cases, a Low signal is output as a logic value. Here, since (e) in FIG. 4 (2) does not exceed the wave height discrimination level 2, a Low signal is output as a logic value.

  Since the High signal is not input as a logic value to the double count removal circuit 46, the double count removal circuit 46 outputs a Low signal as the logic value. Therefore, the processing result of the vibration noise removing unit 4 is a Low signal as a logic value.

  The processing results of the waveform determination unit 3 and the vibration noise removal unit 4 are input to the noise removal circuit 5. As a result of performing an AND operation on the two input signals in the noise removal circuit 5, a high signal is not output as a logic value from the noise removal circuit 5. For this reason, vibration noise is not counted and vibration noise can be removed.

Next, an operation when a normal pulse is not output from the radiation detector 1 and the vibration noise shown in FIG. 4 (3) (a) is input to the amplifier 2 will be described.
The difference from the vibration noise shown in (a) of FIG. 4 (2) is that the end of the vibration noise is the vibration on the negative electrode side in (a) of FIG. 4 (2), whereas in FIG. In (a), it is only a point which is a vibration on the positive electrode side. Therefore, the determination result in the waveform determination unit 3 is a normal pulse, and a high signal is output as a logic value. In the vibration noise removing unit 4, processing results after the synthesis gate circuit 44 are different.

Since the amplitude of the vibration noise is on the positive side, the output of the synthesis gate circuit 44 is different from (e) in FIG. 4 (2) as shown in FIG. waveform which oscillates the positive electrode side may remain without being canceled in the region of the time width W ₁ from. Therefore, in the second wave height discriminating circuit 45, since the wave height value of (e) in FIG. 4 (3) exceeds the wave height discrimination level 2, as shown in (f) of FIG. A signal is output.
Since the determination in the waveform judgment unit 3 is normal pulse, from the noise removing circuit 5 as shown in (g) in FIG. 4 (3), High signal time width W ₃ as a logic value is output. As a result, since the logic value High signal is input to the rate meter circuit 6, it is erroneously counted as a normal analog signal pulse obtained as a result of the radiation detector 1 detecting the radiation.

  However, the waveform shown in (a) of FIG. 4 (3) is a normal analog waveform obtained as a result of the radiation detector 1 detecting radiation immediately after the vibration noise shown in (a) of FIG. In principle, it cannot be distinguished from when a signal pulse is input. For this reason, in order to eliminate the risk of erroneously removing a normal analog signal pulse obtained as a result of detection of radiation by the radiation detector 1, it is not subject to noise removal.

  Next, as shown in FIG. 5, a case where vibration noise is superimposed on a normal analog signal pulse obtained as a result of detection of radiation by the radiation detector 1 will be described. The three patterns (1) to (3) in FIG. 5 show three typical phase differences in order to explain the difference due to the phase difference between the vibration pulse and the normal pulse. FIG. 5 (1) shows the same phase, FIG. 5 (2) shows a 1/4 phase shift, and FIG. 5 (3) shows a 1/2 phase shift.

When the vibration noise is superposed with the same phase, the amplifier 2 outputs a signal shown in (a) of FIG. Since the amplitude of only the normal pulse region is larger than the amplitude of the vibration noise, the signal shown in (c) of FIG. On the other hand, as a result of performing the signal processing in the synthesis gate circuit 44, a signal shown in (e) of FIG. In the signal (e) of FIG. 5 (1), two continuous peak waveforms due to normal pulses appear. Although there remains a vibration component of FIG. 4 (2) in the case of the vibration noise only shown in (c) and also the negative side in the area from the end time width W ₁ of the vibration noise, which is a second wave height of the rear stage It is removed by the discrimination circuit 45. As shown in (f) of FIG. 5 (1), two high signals are continuously output as logic values from the second wave height discriminating circuit 45. The second High signal is removed from the High signal, and one High signal is output. For this reason, the same number of high signals as the number of normal analog signal pulses obtained as a result of detection of radiation by the radiation detector 1 is input to the subsequent rate meter circuit 6 and counted.

  As shown in FIG. 5 (2), even when the phase is shifted by ¼, two continuous peak waveforms caused by normal pulses appear in the output signal of the synthesis gate circuit 44. From the second wave height discriminating circuit 45, as shown in (f) of FIG. 5 (2), two high signals are continuously output as logic values. The second High signal is removed from the High signal, and one High signal is output. For this reason, the same number of high signals as the number of normal analog signal pulses obtained as a result of detection of radiation by the radiation detector 1 is input to the subsequent rate meter circuit 6 and counted.

  As shown in FIG. 5 (3), even when the phase is shifted by ½, two continuous peak waveforms resulting from the normal pulse appear in the output signal of the synthesis gate circuit 44. However, unlike the case of the same phase and ¼ phase shift, when the ½ phase shift occurs, the two continuous peak waveforms overlap, and the second wave height discriminating circuit 45 shows that in FIG. As shown in (f), one High signal is continuously output as a logic value.

  Even if the amplitude of the vibration noise is small and two continuous peak waveforms do not overlap, the second high signal is removed from the two high signals by the double count removal circuit 46 in the subsequent stage, and one high signal is obtained. Is output. For this reason, the same number of high signals as the number of normal analog signal pulses obtained as a result of detection of radiation by the radiation detector 1 is input to the subsequent rate meter circuit 6 and counted.

As described above, in the first embodiment, it is possible to remove a noise signal having a shape significantly different from that of a normal pulse from the radiation detector 1 by performing wave height and waveform determination on an input signal. Further, with respect to the vibration having a frequency close to a normal pulse from the radiation detector 1, by coupling an input signal and a signal which it was allowed to pulse width W ₁ minute delay of normal pulses, and mountain vibration component The troughs cancel each other in amplitude, so that only the vibration component can be removed. Here, the original signal components remaining from the signal input to the delay time W ₁ is not output for shifting the signal acquisition time by using the gate signal which is delayed from the signal input as W _1. Further subjected to second wave height discriminator for the output signal gated, the width of the logic signal output by shaping to twice the pulse width W _1, it is possible to remove vibration noise component .

FIG. 6 is a flowchart showing the noise removal processing of the radiation measuring apparatus described above.
The output of the amplifier 2 is input to the first wave height discriminating circuit 31 and the waveform discriminating circuit 32 of the waveform determining unit 3 (step ST1), and the input pulse wave height is within a predetermined range in the first wave height discriminating circuit 31 and the waveform discriminating circuit 32. And whether the input pulse width is within a predetermined range (steps ST2a and ST2b). The pulse waveform determination circuit 33 determines a normal pulse when the outputs of the first wave height discrimination circuit 31 and the waveform discrimination circuit 32 are both HIGH (step ST3). On the other hand, if it is not within the predetermined range in steps ST2a and ST2b, it is determined as noise.

  Further, the output of the amplifier 2 is input to the vibration noise removing unit 4 (step ST1), and a delay synthesis process is performed by the delay circuit 41 and the synthesis circuit 42 (step ST5). The gate generation circuit 43 generates a gate signal based on the output of the first wave height discrimination circuit 31 (step ST6), and the synthesis gate circuit 44 synthesizes the output from the synthesis circuit 42 using this gate signal. Based on the output of the synthesis gate circuit 44, the second wave height discrimination circuit 45 determines whether the synthesized signal waveform in the gate section is within a predetermined range (step ST7). Double count removal is performed by the count removal circuit 46 (step ST8). On the other hand, if it is not within the predetermined range in step ST7, it is determined as noise.

  The output from the pulse waveform determination circuit 33 and the output from the double count removal circuit 46 are ANDed in the noise removal circuit 5 and output as normal pulses. Since the operation of the rate meter circuit 6 and the operation of the engineering value calculation circuit 7 are known, a detailed description thereof is omitted here.

  As described above, according to the radiation measuring apparatus of the first embodiment, the first wave height discriminating means that receives the analog signal pulse output from the radiation detector and discriminates and outputs the pulse satisfying the predetermined wave height condition. A waveform discrimination means for inputting an analog signal pulse and discriminating and outputting a pulse satisfying a predetermined waveform condition, and whether the waveform of the analog signal pulse is normal based on the outputs of the first wave height discrimination means and the waveform discrimination means A pulse waveform determining means for determining whether or not, a signal synthesizing means for outputting an analog signal pulse obtained by synthesizing an analog signal pulse and a pulse obtained by delaying the analog signal pulse for a predetermined time, and an analog signal pulse output from the radiation detector Generates a gate signal that occurs at the same delay time as the fixed time from the generation timing and lasts longer than the fixed time Among the outputs of the gate generating means and the signal synthesizing means in the section of the gate signal, a second wave height discriminating means for discriminating and outputting a pulse satisfying a predetermined wave height, and a double count generated by the second wave height discriminating means A double count removing means for removing, a noise removing means for removing noise based on the output of the pulse waveform determining means and the output of the double count removing means, and a radiation detector based on the number of output pulses of the noise removing means. Since the detected radiation is measured, the noise component can be reliably removed, and the radiation measurement can be performed accurately.

  Further, according to the radiation measuring apparatus of the first embodiment, since the gate signal is a signal that continues for a time slightly less than twice the fixed time, a normal pulse can be detected correctly and noise removal can be performed. It can be done reliably.

  Further, according to the radiation measuring apparatus of the first embodiment, the double count removing means outputs a signal that lasts twice as long as a certain time at the timing when the output of the second wave height discriminating means is inputted, and While this signal is being output, the output of the second wave height discriminating means is not accepted, so even if a double count of pulses is generated by the second wave height discriminating means, it is surely removed. Can do.

Embodiment 2. FIG.
FIG. 7 is a configuration diagram illustrating the radiation measuring apparatus according to the second embodiment. FIG. 8 is a timing chart conceptually showing the signal processing operation in the second embodiment.

  The radiation measuring apparatus of the second embodiment includes a peak hold circuit 47 in the vibration noise removing unit 4a, and the point that the wave height discrimination level of the second wave height discrimination circuit 45a is determined by the output of the peak hold circuit 47 is implemented. This is a point different from the first mode. That is, the peak hold circuit 47 is a circuit that holds the peak value of the analog signal pulse output from the amplifier 2. The second wave height discrimination circuit 45 a is configured to determine the wave height discrimination level based on the peak wave height value obtained by the peak hold circuit 47. Since other configurations are the same as those of the first embodiment shown in FIG. 3, the corresponding parts are denoted by the same reference numerals and description thereof is omitted.

  In the second embodiment, the signal from the amplifier 2 is branched into three after being input to the vibration noise removing unit 4a, and two of them are directly input to the synthesis circuit 42 as in the first embodiment, The other is input to the synthesis circuit 42 via the delay circuit 41, but the remaining one is input to the peak hold circuit 47 and only the pulse height discrimination level of the second wave height discrimination circuit 45a is variable. Is different from the first embodiment.

A normal analog signal pulse obtained as a result of detection of radiation by the radiation detector 1 is determined by the signal output characteristics of the radiation detector 1 and the circuit constants of the amplifier 2 as shown in FIG. Rise time and fall time are different, and the fall time is longer. Therefore, as shown in (c) of FIG. 8 (1), 2 out of two continuous peaks appearing in the output signal of the synthesis circuit 42. Since the falling component of the input pulse is added to the second peak, the peak value becomes higher than the peak value of the input pulse (input pulse peak value V _p <output pulse peak value V _p ′ of the synthesis circuit 42). ).

Therefore, as shown in (e) of FIG. 8 (1), the peak value V _p ′ of the pulse waveform output from the synthesis gate circuit 44 is higher than the peak value V _p of the input pulse.
On the other hand, as shown in (c) of FIG. 8 (2), the vibration noise, since the rise and fall times are the same, the maximum wave height value of the combined signal as high as the maximum peak value V _p of the input signal It becomes. Therefore, using the fact that the pulse height discrimination level of the second wave height discrimination circuit 45a is variable, as shown in FIG. 8E, the pulse height discrimination level V _p ″ of the second wave height discrimination circuit 45a is set to the peak of the input pulse. set to pulse height discrimination level 3 is slightly higher voltage level than the peak value V _p.

Here, the output of the peak hold circuit 47 is used. Peak hold circuit 47, as shown in FIG. 8 (a), since outputs a voltage corresponding to the peak pulse height V _p of the input pulse, apply voltage V _p to the second pulse height discriminator circuit 45a, the V _p The wave height discrimination level 3 is set to the wave height value V _p ″ obtained by adding a certain ratio to the wave height value. That _is, setting the _{V p <V p ''<} V p ' to become V _p' 'in height discrimination level 3.
As a result, when the input signal is a normal pulse, it exceeds the wave height discrimination level 3, so that a high signal is output as a logic value from the second wave height discrimination circuit 45a as shown in FIG. 8 (1) (f). However, when the input signal is a vibration pulse, since the wave height discrimination level 3 is not exceeded, a high signal is not output as a logic value from the second wave height discrimination circuit 45a as shown in FIG. For this reason, vibration noise is not counted, and vibration noise can be removed.

  Furthermore, as shown in (e) of FIG. 8 (2), for vibration noise, the maximum peak value of the synthesized signal is the same as the maximum peak value of the input signal regardless of the polarity of the vibration component at the end. Thus, it is possible to remove the last positive signal in the vibration noise having the wavelength of (n + 1/2) λ (where λ is one wavelength of the vibration noise and n is an integer) that could not be removed in the first embodiment. Become.

  As described above, according to the radiation measurement apparatus of the second embodiment, the peak hold means for obtaining the peak value of the analog signal pulse output from the radiation detector is provided, and the pulse height discrimination of the second pulse height discrimination means is provided. Since the level is determined based on the peak wave height value, highly accurate noise removal can be performed.

  Further, according to the radiation measuring apparatus of the second embodiment, the pulse height discrimination level is set to be higher than the peak peak value of the analog signal pulse and lower than the peak peak value output from the signal synthesis means. Therefore, vibration noise can be accurately removed.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 1 Radiation detector, 2 Amplifier, 3 Waveform determination part, 4, 4a Vibration noise removal part, 5 Noise removal circuit, 6 Rate meter circuit, 7 Engineering value calculation circuit, 31 1st wave height discrimination circuit, 32 Waveform discrimination circuit, 33 Pulse waveform determination circuit, 41 delay circuit, 42 synthesis circuit, 43 gate generation circuit, 44 synthesis gate circuit, 45, 45a second wave height discrimination circuit, 46 double count removal circuit, 47 peak hold circuit.

Claims (5)

A first wave height discriminating means for inputting an analog signal pulse output from the radiation detector and discriminating and outputting a pulse satisfying a predetermined wave height condition;
Waveform discrimination means for inputting the analog signal pulse and discriminating and outputting a pulse satisfying a predetermined waveform condition;
Pulse waveform determination means for determining whether or not the waveform of the analog signal pulse is normal based on outputs of the first wave height discrimination means and the waveform discrimination means;
A signal synthesis means for outputting an analog signal pulse obtained by synthesizing the analog signal pulse and a pulse obtained by delaying the analog signal pulse for a predetermined time;
An output signal of said first pulse height discriminator means, generated from the generation timing of the analog signal pulses outputted from the radiation detector at a timing time delay comparable to the predetermined time, and longer than the predetermined time Gate generating means for generating a gate signal as a signal that continues for a time;
A second wave height discriminating means for discriminating and outputting a pulse satisfying a predetermined wave height condition among the outputs of the signal synthesizing means in the section where the gate signal continues ;
A double count removing means for removing a double count generated by the second wave height discriminating means;
Noise removing means for removing noise based on the output of the pulse waveform determining means and the output of the double count removing means,
A radiation measuring apparatus for measuring radiation detected by the radiation detector based on the number of output pulses of the noise removing means. According to claim 1, wherein the a W ₁ ≦ W _{2 <2W 1} the analog signal pulse width W ₁ of the time width W ₂ of the section are output from the radiation detector to continue gate signal Radiation measurement device. The double counting removal means from said timing at which the output is the input of a second wave height discriminator, and outputs a signal to continue 2 times the said predetermined time, and, during which the signal is being output, The radiation measuring apparatus according to claim 1, wherein an output of the second wave height discriminating unit is not received. Includes a peak hold means for obtaining a peak pulse height of an analog signal pulse outputted from the radiation detector,
4. The radiation measuring apparatus according to claim 1, wherein a wave height discrimination level of the second wave height discriminating unit is determined based on the peak wave peak value. 5. 5. The radiation measuring apparatus according to claim 4, wherein the peak height discrimination level is higher than the peak peak value of the analog signal pulse and lower than the peak peak value output from the signal synthesis means.

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