JP6067396B2 - Neutron measuring apparatus and neutron measuring method - Google Patents

Description

  Embodiments described herein relate generally to a neutron measurement apparatus and a neutron measurement method.

  At a nuclear power plant, the negative current pulse generated by a neutron detector is converted and amplified by a preamplifier, and the pulse output is counted per unit time by a signal processing device to monitor the reactor output. Is going.

  In the signal processing device, after waveform shaping, voltage amplification, etc. are performed on the pulse signal from the preamplifier, it is smaller than the set voltage level according to the pulse height discrimination (the absolute value is because the target pulse signal is negative) When it is large), a logic pulse is output and the counting circuit performs pulse counting.

  Therefore, even if noise is mixed in the signal, the measurement is not affected if the absolute value is smaller than the set voltage level for the pulse height discrimination.

  However, the current pulse output from the neutron detector is weak, and the surge noise generated from the inverter devices often used in power supply devices and motors around the signal path is large. There is a need to implement noise countermeasures such as installing a ferrite core in the noise propagation path.

  Also in the signal processing device, the signal processing unit is devised to take measures against noise. Since the frequency band of the signal to be measured and the noise generated from the inverter device overlaps, a method of removing noise superimposed on the signal by a filter (filter circuit) before discriminating the wave height cannot be applied. Therefore, for example, when surge noise exceeds the set voltage level for pulse height discrimination, pay attention to the sudden increase of the pulse count value during that time, and within the range that can sufficiently follow the maximum rate of change of the target signal, There are some which limit the follow-up to the change in quantity and minimize the influence by not following the excessive change.

  In the neutron measurement system used in the fusion experimental device, there is a problem of the influence of surge noise generated during the breakdown (discharge phenomenon) of the neutral beam injection (NBI) heating device unique to the fusion experimental device. It becomes.

  As with nuclear power plants, the effect of surge noise generated from nearby inverter devices is also a problem, but the amount of neutron change during fusion experiments is large, and signal processing devices must follow them. This method may not be applicable.

  Further, the follow-up limiting method is not effective against continuously generated surge noise. Therefore, a technique is known that pays attention to the fact that the target signal is negative and surge noise is bipolar.

  For example, a method is known in which a positive and negative wave height discriminating means is provided, noise superposition timing is captured for each positive wave height discrimination, and a logic pulse count by the negative wave height discrimination is gated to prevent erroneous counting during this period. There is also known a method of subtracting the logic pulse count value by the positive wave height discrimination from the logic pulse count value by the negative wave height discrimination.

JP-A-8-82681 JP 2001-183465 A

  The noise superposition timing is captured for each positive wave height discrimination, and during this period, the logic pulse count by the negative wave height discrimination is gated to prevent miscounting. The measurement is performed by subtracting.

  This is an effective method in a place where sudden fluctuation does not occur because the fluctuation of the neutron signal is controlled in a nuclear power plant or the like, and the circuit can also have a simple configuration. However, there is a problem that a measurement error becomes large in order to measure a change in the amount of neutrons generated during a plasma heating experiment using a fusion experimental apparatus performed at a fusion research facility.

For example, assuming that the measurement cycle is 1 ms, and the count value increases by 1, 2, 3,... 10 every 0.1 ms during this period, the count rate per cycle (proportional to the amount of neutrons) )think of. First, the coefficient rate when there is no noise is (1 + 2 + 3 +... +10) / 1 ms = 55/1 ms = 55000 [s ⁻¹ ]. On the other hand, the coefficient rate when noise is detected when 0.9 ms elapses and then counting for 0.1 ms is prohibited is (1 + 2 + 3 +... +9) / (1 ms−0.1 ms) = 45 / 0.9 ms = 50000 [S ⁻¹ ]. As in this example, when the count changes greatly, this conventional technique causes a measurement error.

  In addition, in the method of subtracting the logic pulse count value due to the positive pulse height discrimination from the count value of the logic pulse due to the negative wave height discrimination, the signal and noise are not discriminated when the signal pulse and surge noise overlap. It is expected that the count value is reduced to the signal amount. Therefore, in the case where the cycle of the signal pulse or surge noise is short, the chances of overlapping each other increase, and the measurement error increases.

  Therefore, an object of the embodiment of the present invention is to reduce the influence of surge noise without impairing measurement accuracy even when a signal changes suddenly in a neutron measurement apparatus.

In order to achieve the above-described object, the neutron measurement apparatus according to the embodiment of the present invention is configured to discriminate a pulse height of a unipolar pulse signal generated by a neutron detector and to detect a pulse in a region exceeding a predetermined threshold in the direction of the unipolar side. A unipolar wave high discriminating unit that selects only a signal, a counting unit that counts the pulse signal selected by the unipolar wave high discriminating unit over a predetermined time width interval, and a polarity in a direction opposite to the unipolar pulse signal. An opposite polar wave high discriminating unit that selects a pulse signal in a region exceeding the opposite polarity threshold value, which is a predetermined threshold value in the opposite polarity direction, as the opposite polarity pulse signal. A noise monitoring unit that receives an output and determines whether or not the opposite polarity pulse signal is generated in the predetermined time width interval; a time width setting unit that sets the predetermined time width interval; Each count value in the correction required section which is the time width section in which the counter-polarity pulse signal is detected is corrected immediately before the correction required section in the correction unnecessary section which is the time width section in which the opposite polarity pulse signal is not detected. A count value correction unit that calculates using the immediately preceding count value that is the count value in the unnecessary section and the immediately following count value that is the count value in the correction unnecessary section immediately after the correction required section of the correction unnecessary sections; with a counting rate calculating unit for calculating a counting rate in response to an output from the numerical correction section, wherein the noise monitoring unit is characterized that you count the consecutive number of times that the correction requirement interval.
In addition, the neutron measurement apparatus according to the embodiment of the present invention selects only a pulse signal in a region exceeding a predetermined threshold in the direction of the unipolar side by discriminating the pulse height of the unipolar pulse signal generated by the neutron detector. A polar wave height discriminating unit; a counting unit that counts the pulse signal selected by the monopolar wave high discriminating unit over a predetermined time width interval; and a pulse signal having a polarity opposite to the unipolar pulse signal. Separately, an opposite polar wave high discriminator that selects a pulse signal in a region exceeding the opposite polarity threshold that is a predetermined threshold in the opposite polarity direction as an opposite polarity pulse signal, and an output from the opposite polar wave high discriminator receives the predetermined polar signal. A noise monitoring unit that determines whether or not the opposite polarity pulse signal is generated in a time width interval, a time width setting unit that sets the predetermined time width interval, and the opposite polarity pulse signal Each count value in the correction required section that is the time width section that has been issued is counted in the correction unnecessary section immediately before the correction required section among the correction unnecessary sections that are the time width sections in which the opposite polarity pulse signal is not detected. A count value correction unit that calculates using the immediately preceding count value and the immediately following count value that is a count value in a correction unnecessary section immediately after the correction required section of the correction unnecessary sections; The count rate calculation unit that receives the output and calculates the count rate; and the output of the count value correction unit is integrated for a certain period of time, and the integrated value that is the result of the integration is compared with a preset specified value. And a comparator that outputs an integrated value excessive signal when the specified value is exceeded.

Further, in the neutron measurement method according to the embodiment of the present invention, the noise monitoring unit receives the output from the opposite polar wave height discriminating unit and determines whether or not the opposite polarity pulse signal is generated in the predetermined time interval. A polarity pulse signal confirmation step, a number counting step in which the noise monitoring unit counts the continuous number of consecutive correction required sections which are the time width sections in which the opposite polarity pulse signal is detected, and the opposite polarity pulse signal confirmation step after the count value correction section, in the correcting each count value in the main section, not requiring correction section immediately before the correction requirement section of the of opposite polarity pulse signal the duration interval is not detected not requiring correction section The immediately preceding count value that is a count value, the immediately following count value that is the count value in the correction unnecessary section immediately after the correction required section of the correction unnecessary sections, and the continuous A correction step for calculating using a number, and a count rate calculation step for calculating a count rate in response to an output of the count value correction unit after the correction step. To do.

  According to the embodiment of the present invention, the influence of surge noise can be reduced in a neutron measurement apparatus without impairing measurement accuracy even when a signal changes abruptly.

It is a block diagram which shows the structure of the neutron measuring apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the count value correction | amendment process by the neutron measurement method which concerns on the 1st Embodiment of this invention. It is a wave form diagram which shows the example of the input signal to the neutron measuring device at the time of surge noise mixing for demonstrating the effect of the neutron measuring device which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structure of the neutron measuring apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the count value correction | amendment process by the neutron measurement method which concerns on the 2nd Embodiment of this invention. It is a wave form diagram of a neutron detection signal for explaining an effect of a neutron measuring device concerning a 2nd embodiment of the present invention. It is a block diagram which shows the structure of the neutron measuring apparatus which concerns on the 3rd Embodiment of this invention.

  Hereinafter, a neutron measurement apparatus and a neutron measurement method according to embodiments of the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a block diagram showing the configuration of the neutron measurement apparatus according to the first embodiment of the present invention.

  A unipolar pulse signal output from the neutron detector 1 that has detected neutrons, specifically, a negative pulse signal, that is, a pulse signal having a negative polarity, is weak and is amplified by the preamplifier 2. The neutron measurement device 20 receives the negative pulse signal amplified by the preamplifier 2 and performs measurement by removing surge noise without impairing measurement accuracy.

  The neutron measurement apparatus 20 includes a waveform shaping unit 3, a negative wave height discrimination unit 4, a counter unit 7, a positive wave height discrimination unit 5, a noise monitoring unit 8, a first register 9, a second register 10, a count value correction unit 11, and a count rate. A calculation unit 13 is included. The neutron measurement apparatus 20 includes a time width setting unit 6, a comparison unit 12, and an alarm generation unit 15.

  The waveform shaping unit 3 shapes the waveform of the signal from the preamplifier 2 and amplifies the voltage of the signal. The output signal of the waveform shaping unit 3 is input to the negative wave height discrimination unit 4 and the positive wave height discrimination unit 5.

  When the pulse signal input to the negative wave height discriminating unit 4 is negative and the absolute value is equal to or greater than a predetermined threshold value, the negative pulse signal is output to the counter unit 7. In addition, when it is less than the predetermined threshold, the input pulse signal is not output to the counter unit 7.

  When the pulse signal input to the positive wave height discriminating unit 5 is positive and the absolute value is equal to or greater than a predetermined threshold value, the positive pulse signal is output to the noise monitoring unit 8. In addition, when it is less than the predetermined threshold, the input pulse signal is not output to the noise monitoring unit 8.

  Here, the threshold value used in the negative wave height discriminating unit 4 and the threshold value used in the noise monitoring unit 8 are set independently of each other.

Counter unit 7, for each predetermined time interval T1, and counts the number of the negative pulse signal outputted from the negative electrode height discriminator 4, and outputs the count value C _0. The noise monitoring unit 8 determines whether or not a positive pulse signal is output from the positive wave height discriminating unit 5 at every predetermined time interval T1, and if a positive pulse signal is output from the positive wave height discriminating unit 5 Outputs a noise detection signal.

  Here, the time interval T <b> 1 is set by the time width setting unit 6. The time interval T1 is shorter than the time width in which one surge noise continues, and is set to 5 μs, for example.

The count value C ₀ output from the counter unit 7 and the noise detection signal output from the noise monitoring unit 8 are input to the first register 9. The first register 9 gives a noise detection flag to the count value C ₀ and outputs it as the count value C ₁ after a predetermined holding time.

The second register 10 receives the output C ₁ of the first register 9, after a predetermined holding time, the count value C ₁ which is input, and outputs the grant noise detection flag F2 as the count value C _2. Here, the predetermined holding time in the second register 10 is set by the time width setting unit 6.

The C ₁ noise detection flag F ₁ given to the count value C ₁ and the C ₂ noise detection flag F ₂ given to the count value C ₂ become 1 when a noise detection signal is output from the noise monitoring unit 8. Otherwise, it is 0. Note that the value of the noise detection flag is not limited to 1 and 0. Other values may be used as long as it can be determined whether or not a noise detection signal is output from the noise monitoring unit 8.

  The count value correction unit 11 performs processing according to a noise removal algorithm described later. The count rate calculation unit 13 receives the output from the count value correction unit 11 and calculates the count rate.

  The comparison unit 12 compares the output of the count value correction unit 11 with a specified value. If the output of the count value correction unit 11 is equal to or higher than the specified value, a signal indicating that the output is equal to or higher than a predetermined specified value is output to the noise monitoring unit. 8 and the count rate calculation unit 13. Further, when the value exceeds the specified value for warning, a signal indicating that the value is higher than the specified value for warning is output to the alarm generating unit 15.

  FIG. 2 is a flowchart showing a count value correction process by the neutron measurement method according to the first embodiment of the present invention. Specifically, it is a flowchart of processing in the count value correction unit 11.

First, the value of _{C 2} noise detection flag F2, determines the presence or absence of _{C 2} noise detection (step S1). When F2 is 1, i.e., when it is determined that there is C ₂ noise detection, was added 1 to the noise detection count of sequential value P (step S2), the count value of the C ₂ noise detection has been judged time interval Enter replacement step. Note that the initial value of P is 0.

Moreover, when the F2 is 0, i.e., when it is determined that no _{C 2} noise detection flag is not replacement of the count value, _{C 2} '= _{C 2} by _{C 2'} and set the value of (step S6), and C ₃ = C ₂ 'by setting the value of _{C 3} (step S7). Further, the noise detection continuous number of times value P is reset to 0, and P = 0 is output (step S8).

On the other hand, when it is determined that _{C 2} noise detection, after step S2, and check the _{C 1} noise detection flag F1 determines the presence or absence of _{C 1} noise detection (step S3). F1 = 1 i.e. if it is determined that there _{C 1} noise detection, 'replace the 0, _{C 2'} count value _{C 2} as = 0 (step S4), and outputs the value of the _{C 2} '= 0 and P.

Also, if it is determined that there is no C ₁ noise detected by F1 = 0 or step S3, replacing the count value of the determined time interval that there is C ₂ noise detection. That is, the count value is linearly interpolated and output as C ₂ ′ = P (C ₁ + C ₃ ) / 2 (step S5). Further, the noise detection continuous number P is reset to 0 (step S8).

C ₂ ′, or C ₂ ′ and C ₃ output from the count value correction unit 11 are used by the count rate calculation unit 13.

  The noise detection continuous frequency value P is compared with an upper limit value set in advance in the comparison unit 12, and if the noise detection continuous frequency value P is larger than the upper limit value, the function of the noise monitoring unit 8 is invalidated to the noise monitoring unit 8. A command signal is output for

  When the noise detection continuous number of times P exceeds the specified value, a warning signal is output to the alarm generation unit 15, and the alarm generation unit 15 issues an alarm. The specified value is usually set to a value lower than the upper limit value.

  In this embodiment, when the noise detection continuous frequency value P exceeds the specified value, an alarm is issued from the alarm generation unit 15, and when the noise detection continuous frequency value P exceeds the upper limit value, the function of the noise monitoring unit 8 is disabled. However, counting may be performed continuously and only an alarm may be issued.

  In this case, for example, when there is a defect in the integration part of the noise detection continuous number of times value P, it is possible to determine later which time the measurement was effective and to leave data that may be used. .

  FIG. 3 is a waveform diagram showing an example of an input signal to the neutron measurement apparatus when surge noise is mixed for explaining the effect of the neutron measurement apparatus according to the first embodiment of the present invention. Among these, the neutron detection signal is a signal extending to the negative electrode side (downward from the time axis).

  In the example shown in FIG. 3, the count value of the neutron detection signal is 1 in the time width interval t1 and 5 in the time width interval t5. On the other hand, noise signals are superimposed in the time width sections t2, t3, and t4 sandwiched between the time width section t1 and the time width section t5. Below, the result of the arithmetic processing performed in the count value correction | amendment part in each time width area is demonstrated.

First, in the duration interval t1, for the _{C 2} noise detection flag = 0, the processing as _{C 2 '= 1, C 3} = C 2' = 1, P = 0.

In the next time interval t2, since C ₂ noise detection flag = 1, P = 0 + 1 = 1, and since C ₁ noise detection flag = 1, C ₂ ′ = 0 is calculated.

In the next section t3, for _{C 2} noise detection flag = 1, for P = 1 + 1 = 2, _{C 1} noise detection flag = 1, the processing as _{C 2} '= 0.

In the next duration interval t4, since the _{C 2} noise detection flag = 1, for P = 2 + 1 = 3, _{C 1} noise detection flag _{= 0, C 2 '= P} (C 1 + C 3) / 2 = 9 Is calculated. However, the count value _{C 1} in the duration interval t5 is 5, the count value _{C 3} held in the time width period t1 is 1. Further, P = 0.

From the above results, the total of the count values C ₂ ′ obtained in each of the time width interval t2, the time width interval t3, and the time width interval t4 is 9.

  On the other hand, the count value of the neutron signal in the time width interval t1 is 1, and the count value of the neutron signal in the time width interval t5 is 5. When linear interpolation is performed using these count values, the time width interval t2, time The count values of the width interval t3 and the time interval t4 are 2, 3, and 4, respectively.

This total value is 2 + 3 + 4 = 9, and the sum of the count values C ₂ ′ is equal to 9. In this way, the count value correction unit 11 performs error interpolation by linearly interpolating the count value of the time width section where noise is superimposed using the count value of the time width section where noise is not superimposed before and after this. Small corrections can be made.

  In the present embodiment, an example of linear interpolation is shown. If the time interval T1 is set sufficiently short with respect to an assumed signal change, measurement accuracy with no problem with linear interpolation (linear approximation) can be obtained. However, it is not limited to linear interpolation. For example, more complicated nonlinear correction may be performed more strictly.

  As described above, according to the present embodiment, the influence of noise can be effectively reduced without impairing measurement accuracy with a simple circuit configuration even under a situation where the neutron to be measured fluctuates rapidly.

[Second Embodiment]
FIG. 4 is a block diagram showing a configuration of a neutron measurement apparatus according to the second embodiment of the present invention. This embodiment is a modification of the first embodiment.

  In the present embodiment, a line is added in which the count rate R, which is the output value of the count rate calculation unit 13, is fed back to the count value correction unit 11. The count value correcting unit 11 compares the count rate R sent from the count rate calculating unit 13 with a predetermined set value to determine the magnitude.

  FIG. 5 is a flowchart showing a count value correction process by the neutron measurement method according to the second embodiment of the present invention. In the present embodiment, a count rate determination step S9 is added before the flow of steps in the first embodiment according to the flowchart shown in FIG.

When it is determined that the count rate R sent from the count rate calculation unit 13 is not larger than the set value, the process proceeds to step S1 and the same correction process as in the first embodiment is performed. . FIG. 5 shows an example in which the predetermined set value is set to 1 × 10 ⁶ cps, for example.

When it is determined that the count rate R sent from the count rate calculation unit 13 is larger than the set value, the subsequent correction process is not performed and the count value is not replaced, and C ₂ ′ = C ₂ the 'set the value of (step _{S6), C 3 = C 2} ' C 2 to set the value of _{C 3} (step S7). Further, the noise detection continuous number of times value P is reset to 0, and P = 0 is output (step S8).

  FIG. 6 is a waveform diagram of a neutron detection signal for explaining the effect of the neutron measurement apparatus according to the second embodiment of the present invention. As shown in FIG. 6, the neutron detection signal is basically a negative pulse signal, but overshoot occurs on the positive electrode side after returning from the negative electrode side to the zero direction.

  Since the number of neutron signals is small when the count value (count rate) per unit time is small, the probability that the neutron signals overlap each other is very small, and the influence on the measurement can be ignored. However, as the count value (counting rate) per unit time increases, the probability of multiple overlapping neutron detection signals increases.

  For this reason, the level of the detection signal is superimposed, and thereby becomes higher than the voltage value set by the pulse height discrimination on the positive electrode side. When it becomes higher than the voltage value set by the positive-side wave height discrimination, it is determined as a noise signal, which may cause erroneous detection.

  According to the present embodiment, it is possible to prevent erroneous detection of noise by performing the count rate determination at the beginning of the processing flow in the count value correction unit 11.

[Third Embodiment]
FIG. 7 is a block diagram showing a configuration of a neutron measurement apparatus according to the third embodiment of the present invention. This embodiment is a modification of the second embodiment, and is further provided with a positive wave height discrimination voltage set value calculation unit 14.

  When the count rate value output from the count rate calculator 13 exceeds the positive pulse height discrimination voltage set value, the positive wave height discrimination voltage set value calculator 14 changes the threshold value together with the count rate value to the positive wave height discriminator 5. Outputs a command.

  When the positive wave height discriminating unit 5 receives the count rate value and the threshold value change command from the positive wave height discriminating voltage set value calculating unit 14, the positive wave height discriminating unit 5 changes the positive wave height discriminating threshold to an appropriate threshold according to the count rate value.

  When the count rate value increases, the neutron detection signals overlap, the voltage level also rises on the positive electrode side, exceeds the positive wave height discrimination voltage setting value, and there is a risk of erroneous detection.

  According to the configuration of the present embodiment, as the count rate increases, the threshold value is changed to an appropriate threshold according to the count rate value, so that erroneous detection in noise detection can be prevented.

[Other Embodiments]
As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. For example, in each embodiment, the output of the neutron detector is described as a negative pulse signal, that is, a unipolar pulse signal having a negative polarity, but is not limited to negative polarity.

  For example, the present invention can be similarly applied as a unipolar pulse signal when the polarity is inverted in signal processing and the signal of the neutron detector is handled as positive polarity. In this case, the noise monitoring unit, on the contrary, performs wave height discrimination on the negative electrode side.

  Moreover, you may combine the characteristic of each embodiment. For example, in the third embodiment, a response such as a warning based on a determination result in the comparison unit 12 that is a feature in the second embodiment and a count rate value that is a feature added in the third embodiment are used. It has the characteristics of both changes of the threshold value. The feature of changing the threshold value according to the count rate value added in the third embodiment may be combined with the first embodiment.

  Furthermore, these embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

  These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Neutron detector, 2 ... Preamplifier, 3 ... Waveform shaping part, 4 ... Negative wave height discrimination part (unipolar wave high discrimination part), 5 ... Positive wave height discrimination part (opposite polar wave height discrimination part), 6 ... Time width Setting unit, 7: Counter unit (counting unit), 8: Noise monitoring unit, 9: First register, 10: Second register, 11: Count value correcting unit (counting value correcting unit), 12: Comparison unit, 13 ... Count rate calculation unit, 14 ... Positive wave height discrimination voltage setting value calculation unit (opposite polar wave height discrimination voltage setting value calculation unit), 15 ... Alarm generation unit, 20 ... Neutron measurement device

Claims (7)

A unipolar wave high discriminator for selecting only a pulse signal in a region exceeding a predetermined threshold in the direction of the unipolar side by discriminating the unipolar pulse signal generated by the neutron detector;
A counting unit that counts the pulse signal selected by the unipolar wave high discrimination unit over a predetermined time width interval;
The pulse width of the pulse signal having a polarity opposite to that of the unipolar pulse signal is discriminated from the pulse height, and a pulse signal in a region exceeding the opposite polarity threshold value which is a predetermined threshold value in the opposite polarity direction is selected as the opposite polarity pulse signal. A discrimination section;
A noise monitoring unit that receives an output from the opposite polar wave height discriminating unit and determines whether or not the opposite polarity pulse signal is generated in the predetermined time interval;
A time width setting unit for setting the predetermined time width interval;
The respective count values in the correction required section that is the time width section in which the opposite polarity pulse signal is detected are calculated immediately before the correction required section in the correction unnecessary section that is the time width section in which the opposite polarity pulse signal is not detected. A count value correction unit that calculates using the immediately preceding count value that is the count value in the correction unnecessary section and the immediately subsequent count value that is the count value in the correction unnecessary section immediately after the correction required section of the correction unnecessary section;
A count rate calculation unit that receives the output from the count value correction unit and calculates a count rate;
Equipped with a,
The noise monitoring unit neutron measuring apparatus characterized that you count the consecutive number of times that the correction requirement interval. 2. The neutron measurement apparatus according to claim 1, wherein the noise monitoring unit outputs an alarm signal when the number of consecutive times exceeds a preset number of times . A unipolar wave high discriminator for selecting only a pulse signal in a region exceeding a predetermined threshold in the direction of the unipolar side by discriminating the unipolar pulse signal generated by the neutron detector;
A counting unit that counts the pulse signal selected by the unipolar wave high discrimination unit over a predetermined time width interval;
The pulse width of the pulse signal having a polarity opposite to that of the unipolar pulse signal is discriminated from the pulse height, and a pulse signal in a region exceeding the opposite polarity threshold value which is a predetermined threshold value in the opposite polarity direction is selected as the opposite polarity pulse signal. A discrimination section;
A noise monitoring unit that receives an output from the opposite polar wave height discriminating unit and determines whether or not the opposite polarity pulse signal is generated in the predetermined time interval;
A time width setting unit for setting the predetermined time width interval;
The respective count values in the correction required section that is the time width section in which the opposite polarity pulse signal is detected are calculated immediately before the correction required section in the correction unnecessary section that is the time width section in which the opposite polarity pulse signal is not detected. A count value correction unit that calculates using the immediately preceding count value that is the count value in the correction unnecessary section and the immediately subsequent count value that is the count value in the correction unnecessary section immediately after the correction required section of the correction unnecessary section;
A count rate calculation unit that receives the output from the count value correction unit and calculates a count rate;
Comparing the output of the count value correction unit for a certain period of time, comparing the integrated value as a result of the integration with a preset specified value, and outputting an excessive integrated value signal when the integrated value exceeds the specified value And
The neutral child measuring device you comprising: a. The neutron measurement apparatus according to claim 3, further comprising an alarm generation unit that issues an alarm when the comparison unit outputs the integrated value excessive signal . 4. The neutron measurement apparatus according to claim 3, wherein the opposite polar wave height discriminating unit increases the value of the opposite polarity threshold when the comparison unit outputs the integrated value excessive signal . Wherein each of the count values in the corrected main section, neutrons as claimed in any one of claims 1 to claim 5, characterized in that it is calculated by linear interpolation using the immediately count the said immediately preceding count value Measuring device. The noise monitoring unit receives the output from the opposite polar wave height discriminating unit, and determines whether or not the opposite polarity pulse signal is generated in a predetermined time width section,
The noise monitoring unit counts the number of consecutive consecutive times of the correction required section that is the time width section in which the opposite polarity pulse signal is detected ;
After said opposite polarity pulse signal confirmation step, the count value correction unit, the correction of each count value in the main section, the correction requirement interval of the being the duration interval is not detected opposite polarity pulse signal correction required interval Calculated using the immediately preceding count value that is the count value in the correction unnecessary section immediately before, the immediately following count value that is the count value in the correction unnecessary section immediately after the correction required section of the correction unnecessary sections, and the continuous count A correction step to
After the correction step, the count rate calculation unit receives the output of the count value correction unit and calculates the count rate,
A neutron measurement method characterized by comprising:

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