JP2012007889A - Radiation monitor and method for gain compensation of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation monitor used at a nuclear power plant which is capable of measuring with high accuracy reflecting the detector operating characteristics depending on fluctuations such as a temperature fluctuation, an aged deterioration and a dose rate fluctuation, etc. of a radiation detector.SOLUTION: A radiation monitor comprises: a radiation detector for measuring the radiation of an installation environment with being installed in a reactor building; a detector power supply of the radiation detector; a gain adjustment device for variably adjusting an output gain of the radiation detector; a multichannel pulse height analyzer for calculating a γ-ray energy spectrum from the output of the gain adjustment device; a peak calculation device for calculating a γ-ray peak center measured value of a γ-ray peak on the γ-ray energy spectrum calculated by the multichannel pulse height analyzer; a peak discrimination device for discriminating a gain compensation by calculating the deviation of the γ-ray peak center measured value calculated by the peak calculation device from a γ-ray peak center set value; a gain compensation device for adjusting the gain of the gain adjustment device by determining a gain adjustment amount to adjust the deviation from the γ-ray peak center set value calculated by the peak discrimination device.

Description

  The present invention relates to a radiation monitor that compensates for gain fluctuations of a radiation detector of a radiation monitor used in a nuclear power plant and a gain compensation method for the radiation monitor.

Numerous and various types of radiation monitors are installed in nuclear power plants, and radiation detectors such as semiconductor detectors, ionization chambers, and scintillation detectors are used as radiation monitors according to the type and level of radiation to be measured. .
These radiation monitors are required to be highly reliable and highly accurate from the viewpoint of maintaining the operational soundness of nuclear power plants and managing the exposure of workers. However, fluctuations in the temperature environment and dose rate environment at various radiation monitor installation positions and continuous operation over a long period of time may cause gain fluctuations in the radiation detector, which may cause deterioration in the performance of the radiation monitor.

  Here, in the case of a radiation monitor in a nuclear power plant reactor building and a reactor containment vessel inside the nuclear reactor building, temperature and dose rate fluctuations from periodic inspections to rated operation are not limited even in the nuclear plant radiation monitor installation environment. It turns out to be extremely large. In addition, it is known that the radionuclide, which is the main cause of the dose rate from the periodic inspection to the rated operation, varies depending on the reactor power and the reactor operation status.

  As a gain compensation technique for a conventional radiation monitor, Japanese Patent Laid-Open No. 2006-29986 discloses a technique for compensating gain from a peak value corresponding to the specific radionuclide on the energy spectrum with reference to the radiation energy of the specific radionuclide. It is disclosed. There is also a gain compensation technique that matches the temperature characteristics of the radiation detector by adjusting the applied voltage value of the photomultiplier tube with temperature information from a thermometer installed in the vicinity of the radiation detector.

As another example of the gain compensation technique, there is a technique that performs gain compensation by inputting an arbitrary light intensity at an arbitrary period using a light source such as a light emitting diode (LED).
Japanese Patent No. 1942035 discloses a technique for compensating for the gain of a radiation monitor by using an LED and an LED driver that controls the light emission amount and frequency to collect charge pulses by known light pulses. Yes.

  Further, as a known example, there is a technique in which a calibration radiation source such as Cs-137 is attached to a radiation monitor, and gain compensation is performed by combining information such as the radiation monitor output from the attachment radiation source, the attachment radiation source intensity, and radiation energy.

  Japanese Patent Laid-Open No. 09-304542 uses a calibration radiation source by combining radiation monitor output by radiation of natural radioactive materials such as K-40 and Tl-208, and information on the intensity and radiation energy of the natural radioactive materials. A technique for compensating for the gain is disclosed.

JP 2006-29986 A Japanese Patent No. 1942035 JP 09-304542 A

  In the case of a radiation monitor in a nuclear power plant reactor building and in a reactor containment vessel inside the reactor building, temperature and dose rate fluctuations at the installation position from periodic inspection to rated operation are also part of the radiation monitor installation environment of the nuclear power plant. Very large. In addition, the radionuclide, which is the main cause of the dose rate from the periodic inspection to the rated operation, varies depending on the reactor power and the reactor operation status.

  Regarding the gain compensation method disclosed in Japanese Patent Application Laid-Open No. 2006-29986, when the gain compensation method of Patent Document 1 is applied to a radiation monitor in a nuclear reactor reactor building and a reactor containment vessel in a nuclear reactor building, The peak of the specific radionuclide applied for compensation cannot be measured due to the influence of other radionuclides in any one nuclear plant cycle between periodic inspection, reactor start-up, rated operation, reactor shutdown, and periodic inspection. Or the case where it cannot measure with sufficient accuracy occurs. For this reason, it is necessary to link the indicator nuclides according to the reactor power and the reactor operation status.

  In the technique disclosed in Japanese Patent Application Laid-Open No. 2006-29986, the applied voltage value of the radiation detector is adjusted based on the temperature information from the thermometer. However, the energy resolution is deteriorated by changing the applied voltage value. May be incurred. Furthermore, since the temperature information from the thermometer does not strictly indicate the temperature of the radiation detector itself, a temperature difference due to a temperature gradient between the radiation detector and the thermometer is generated, resulting in a measurement error.

  In the case of the technique disclosed in Japanese Patent No. 1942035, most of the target radiation monitors are limited to radiation monitors using Si semiconductor detectors. It is difficult to compensate for gain by LEDs of other general radiation detectors such as an ionization chamber, a Ge detector, and a scintillation detector. Moreover, since the LED itself also has temperature characteristics and aging deterioration, it is difficult to perform highly accurate gain compensation.

  When a calibration radiation source such as Cs-137 is used, a radiation source having an intensity capable of sufficiently collecting γ-ray peaks is required even in a high dose rate environment during reactor rated operation. When installing a calibration radiation source having sufficient strength that can be used even during the rated operation of the reactor, the exposure of workers during periodic inspections with this calibration radiation source may become a problem.

  Like the technique disclosed in Japanese Patent Application Laid-Open No. 09-304542, gain compensation technology using natural radioactive materials such as K-40 and Tl-208 is used in a nuclear power plant reactor building, and a nuclear reactor in the reactor building. The dose rate in the installation environment of the radiation monitor in the containment vessel is very large compared to the radiation of natural radioactive materials such as K-40 and Tl-208. For this reason, it is difficult to collect γ-ray peaks due to natural radioactive substances.

  An object of the present invention is to provide a radiation monitor and a gain of the radiation monitor used in a nuclear power plant capable of high-accuracy measurement reflecting a detector operation characteristic due to fluctuations in temperature, aging, or dose rate fluctuations of the radiation detector. It is to provide a compensation method.

  The radiation monitor of the present invention is a radiation detector that is installed in a reactor building and measures radiation in an installation environment, a detector power supply of the radiation detector, and a gain that can variably adjust an output gain of the radiation detector. An adjustment device, a multi-channel wave height analyzer that calculates a γ-ray energy spectrum from the output of the gain adjustment device, and a γ-ray peak center measurement value of a γ-ray peak on the γ-ray energy spectrum calculated by the multi-channel wave height analyzer A peak calculating device that calculates a difference between the measured γ-ray peak center value calculated by the peak calculating device and a γ-ray peak center setting value and determining gain compensation, and the peak determining device A gain compensation device for determining a gain adjustment amount for adjusting a deviation from the calculated γ-ray peak center setting value and adjusting a gain of the gain adjustment device; It includes, and maintains measurement accuracy of the radiation detector to compensate for the gain of the radiation detector.

  The radiation monitor of the present invention includes a plurality of radiation detectors installed in a reactor building and measuring radiation in a plurality of installation environments, a plurality of detector power supplies of the radiation detector, and an output of the radiation detector A plurality of gain adjusting devices capable of variably adjusting the gain, a plurality of multi-channel wave height analyzers for calculating a γ-ray energy spectrum from the output of the gain adjusting device, and a γ-ray energy spectrum calculated by the multi-channel wave height analyzer A plurality of peak calculation devices for calculating γ-ray peak center measurement values of γ-ray peaks, and a gain compensation by calculating a difference between the γ-ray peak center measurement value calculated by the peak calculation device and a γ-ray peak center setting value A gain adjustment amount for adjusting a deviation between a plurality of peak discriminating devices for discriminating between the γ-ray peak center set value calculated by the peak discriminating device and determining the gain. A plurality of gain compensation devices for adjusting the gain of the gain adjustment device, a gate for outputting a gate signal from the outputs of the N radiation detectors obtained by branching the output of the gain adjustment device, and the gate A multi-channel wave height analyzer that forms a γ-ray energy spectrum based on the output gate signal and a scaler that counts the gate signal of the gate, and compensates the gain for any of the plurality of installed radiation detectors. The measurement accuracy of the γ-ray energy spectrum by the gate signal is maintained by maintaining the correlation between the outputs of the respective radiation detectors.

The gain compensation method for a radiation monitor according to the present invention is used in a nuclear reactor plant reactor building, a radiation detector for measuring radiation in an installation environment, a detector power supply for the radiation detector, and an output of the radiation detector. A gain adjustment device capable of variably adjusting the gain, a multi-channel wave height analyzer for calculating a γ-ray energy spectrum from the output of the gain adjustment device, and a γ-ray peak center measurement value of a γ-ray peak on the γ-ray energy spectrum. A peak calculating device for calculating, a peak discriminating device for calculating a difference between the γ-ray peak center measured value calculated by the peak calculating device and a γ-ray peak center setting value, and determining gain compensation; and the γ-ray peak center A gain of a radiation monitor having a gain compensation device for determining a gain adjustment amount for adjusting a deviation from a set value and adjusting a gain of the gain adjustment device. An index for gain compensation of specific radionuclides (hereinafter referred to as main nuclides at regular inspections) that can be confirmed by the reactor power and reactor operation status at the time of reactor shutdown and periodic inspection As the nuclide, the specific radionuclide that can be confirmed by the reactor power and reactor operating status (hereinafter referred to as the rated nuclide) is used as the index nuclide for gain compensation.
During reactor start-up operation and shutdown operation, depending on the reactor power and reactor operation status, the main nuclides at the regular inspection and the main nuclides at the rated time are used as index nuclides, respectively, depending on the reactor output and the reactor operation status. The gain of the radiation detector is compensated using the index nuclide.

  Further, the gain compensation method of the radiation monitor of the present invention is used in a nuclear reactor plant reactor building, and a plurality of radiation detectors respectively measuring radiation in a plurality of installation environments, and a plurality of detector power supplies of the radiation detector. A plurality of gain adjustment devices that can variably adjust the output gain of the radiation detector, a plurality of multichannel wave height analysis devices that calculate a γ-ray energy spectrum from the output of the gain adjustment device, and the multichannel wave height analysis device A plurality of peak calculation devices for calculating the γ-ray peak center measurement value of the γ-ray peak on the γ-ray energy spectrum calculated in step 1, and the γ-ray peak center measurement value and the γ-ray peak center setting value calculated by the peak calculation device And a plurality of peak discriminating devices for calculating gain compensation and determining gain compensation, and a γ-ray peak center setting value calculated by the peak discriminating device. A plurality of gain compensators that determine the gain adjustment amount for adjusting the gain and adjust the gain of the gain adjuster, and further output the outputs of the N radiation detectors obtained by branching the output of the gain adjuster Gain compensation of a radiation monitor, comprising: a gate that outputs a gate signal from the gate; a multichannel wave height analyzer that forms a γ-ray energy spectrum by the gate signal output from the gate; and a scaler that counts the gate signal of the gate This is a method, and at the time of reactor shutdown and periodic inspection, a specific radionuclide (hereinafter referred to as main nuclide at the time of regular inspection) that can be confirmed by the reactor power and reactor operation status is used as an index nuclide for gain compensation. The indicator nuclides at the rated operation of the reactor include the specific radionuclides that can be confirmed by the reactor power and the reactor operating status ) As the index nuclide for gain compensation, and during the reactor start-up operation and shutdown operation, the main nuclide at the regular inspection and the main nuclide at the rated time are selected as the index nuclide according to the reactor power and reactor operation status. Γ-ray energy by the gate signal by compensating the gain of the radiation detector using each index nuclide according to the reactor output and the reactor operation status, and maintaining the correlation of the output of each radiation detector It is characterized by maintaining the measurement accuracy of the spectrum.

  According to the present invention, a radiation monitor used in a nuclear power plant capable of high-accuracy measurement reflecting the detector operating characteristics due to fluctuations such as temperature fluctuation, aging deterioration, or dose rate fluctuation of the radiation detector, and the gain of the radiation monitor A compensation method can be realized.

The block diagram which shows the measurement environment compensation type | mold radiation monitor installed in the nuclear reactor containment vessel in the reactor building which is 1st Example of this invention. An example of the gamma ray energy spectrum which can be acquired with the multichannel wave height analyzer in the reactor output of 1st Embodiment and the reactor operation condition. FIG. 5 is another example of a γ-ray energy spectrum that can be acquired by the multichannel wave height analyzer in the reactor output and reactor operation status of the first embodiment. FIG. 5 is still another example showing a γ-ray energy spectrum that can be acquired by the multi-channel wave height analyzer in the reactor power and reactor operation status of the first embodiment. An example of the gamma ray energy spectrum which shows the fluctuation | variation of the gamma ray peak in the reactor output of Example 1, and a reactor operation condition. FIG. 6 is a characteristic diagram showing the relationship between the γ-ray peak fluctuation value of the index nuclide of Example 1 and the gain adjustment value. Explanatory drawing which shows the reactor power of Example 1, and the reactor power in a nuclear reactor operating state, the main nuclide index area | region at the time of a regular inspection, and the main nuclide index area | region at the time of a rating. 6 is a follow chart showing a processing procedure of a gain compensation method in the measurement environment compensation type radiation monitor of the first embodiment. Explanatory drawing which shows the reactor power of Example 2, and the reactor power in a reactor operation condition, the main nuclide index area | region at the time of a regular inspection, and the main nuclide index area | region at the time of a rating. Explanatory drawing which shows an example of the reactor power of Example 3, the reactor power in the reactor operation status, the main nuclide index region at the time of regular inspection, and the main nuclide index region at the time of rating. Explanatory drawing which shows other examples of the reactor power of Example 3, and the reactor power in the reactor operation status, the main nuclide index region at the time of regular inspection, and the main nuclide index region at the time of rating. The block diagram which shows the measurement environment compensation type | mold radiation monitor installed in the reactor containment vessel in the reactor building which is 4th Example of this invention.

  The knowledge about the measurement environment compensation type radiation monitor of the present invention will be described. The measurement environment compensation type radiation monitor of the present invention is a radiation monitor gain variation of the radiation monitor according to the installation environment and measurement environment of the radiation detector without using the calibration radiation source, natural radioactive material, light source and temperature information. This is based on new knowledge obtained when various studies are made on a measurement environment compensation type radiation monitor and its gain compensation method.

  This knowledge includes a radiation detector that measures radiation in an installation environment used in a nuclear power plant, a detector power supply for the radiation detector, a gain adjustment device that can variably adjust the output gain of the radiation detector, and a gain adjustment device. A multi-channel wave height analyzer that calculates a γ-ray energy spectrum from the output of the output, a peak calculator that calculates a γ-ray peak center measurement value of a γ-ray peak on the γ-ray energy spectrum calculated by the multi-channel wave height analyzer, and a peak A peak discriminating device for discriminating gain compensation by calculating a deviation between the γ-ray peak center measured value calculated by the calculating device and the γ-ray peak center set value; and a γ-ray peak center measured value calculated by the peak discriminating device 5 And a gain compensation device that determines a gain adjustment amount for adjusting a deviation between the γ-ray peak center setting value and adjusts a gain of the gain adjustment device. Therefore, at the time of reactor shutdown and periodic inspection, a specific radionuclide (hereinafter referred to as the main nuclide at the time of regular inspection) that can be confirmed by the reactor power and reactor operation status is used as an index nuclide for gain compensation, The index nuclide during reactor rated operation is a specific radionuclide that can be confirmed by the reactor power and reactor operation status (hereinafter referred to as the main nuclide at rated time) as the index nuclide for gain compensation, and the reactor start-up operation At the time of reactor (at the time of reactor startup) and at the time of shutdown (at the time of reactor shutdown), depending on the reactor power and reactor operation status, the main nuclides at the time of regular inspection and the main nuclides at the time of rating are used as index nuclides. A measurement environment compensation type radiation monitor and a gain compensation method thereof compensate for the gain of the radiation detector using an index nuclide corresponding to each reactor power and reactor operation state.

  Next, the contents of the new knowledge will be specifically described.

A general γ-ray detector is used as a radiation detector for measuring radiation in an installation environment used in a nuclear power plant. Examples of γ-ray detectors include Ge, Si, CdTe, CZT, etc. in the case of a semiconductor detector, and NaI (Tl), CsI (Ce), LaBr ₃ (Ce) in the case of a scintillation detector. ), Organic scintillators in addition to inorganic scintillators such as BGO, GSO, LuAG (Pr), LSO, and YAP.

  Both are applicable to radiation monitors. A typical γ-ray detector is equipped with a preamplifier to maintain energy resolution. In the case of a scintillation detector, a photodetector for converting light emitted from the scintillator into an electrical signal is required.

  Commonly used photodetectors are photomultiplier tubes, photodiodes and avalanche photodiodes. In addition to directly adhering the scintillator and the light detector with optical grease, there is a means for suppressing deterioration of light collection efficiency due to a difference in geometric conditions between the scintillator and the light detector through a light guide.

The power source of the radiation detector is a power source generally used in radiation measurement. The preamplifier and the photodetector are operated by this power source, and a signal is output to the circuit system at the subsequent stage.
The gain adjusting device attached to the subsequent stage of the radiation detector can adjust the output gain with respect to the external input corresponding to the gain adjustment amount.

As the multichannel wave height analyzer, a general device used in normal radiation measurement is used. A general multi-channel wave height analyzer has a function of forming a γ-ray energy spectrum by shaping the output of a radiation detector with a linear amplifier or the like and performing analog-digital (AD) conversion.
In addition, the output of the radiation detector is AD converted, and a gamma ray energy spectrum is formed by digitally processing the signal using a programmable logic device (PLD: Programmable Logic Device) or FPGA (Field Programmable Gate Array). There is also a multi-channel pulse height analyzer using a digital signal processor (DSP).

  The peak calculation device performs processing such as differentiation of the γ-ray peak on the γ-ray energy spectrum acquired by the multi-channel pulse height analyzer, smoothing of the γ-ray energy spectrum and the channel corresponding to the γ-ray energy, It has a function of calculating a γ-ray peak center measurement value, a ROI (Region Of Interest) of the γ-ray peak, and the like.

  The peak discriminating device has a function of discriminating a difference between the γ-ray peak center measurement value calculated by the peak calculation device and a preset γ-ray peak center setting value. When a significant shift of the γ-ray peak center can be confirmed, a signal for permitting gain adjustment is output to a gain compensator described later.

  The gain compensation device has a function of determining a gain adjustment amount for adjusting a deviation from the γ-ray peak center setting value and adjusting a gain of the gain adjustment device. When a signal permitting gain adjustment is input from the peak discriminator, the gain adjustment amount for adjusting the γ-ray peak center measurement value to the γ-ray peak center setting value is determined, and the signal corresponding to the gain adjustment amount is adjusted to the gain adjustment. Enter into the device. When no signal for permitting gain adjustment is input from the peak discriminating device, gain adjustment is not performed.

  Regarding indicator nuclides in reactor power and reactor operation status, indicator nuclides at the time of reactor shutdown and periodic inspection (main nuclides during regular inspection) are generated by reactor operation, and piping, equipment, and plant during reactor operation Adhere to structures. Or it exists in the primary coolant. Examples of main nuclides at regular inspection include Co-60, Co-58, Mn-54, Fe-59, Eu-152, Eu-154, Sc-46, Zn-65, Cs-134, Ta-182, Rh -106, Nb-94, Cr-51 and the like.

Co-60 is a radionuclide generated by the (n, γ) reaction of Co-59, and emits γ-rays mainly having energy of 1173 keV and 1332 keV by β ^- decay. Since the half-life is 5.27 years, Co-60 generated during reactor operation can be confirmed even when the reactor is shut down and during periodic inspections.

Co-58 is a radionuclide generated by the (n, p) reaction of Ni-58, and emits gamma rays having energies of 811 keV and 511 keV mainly by electron capture and β ⁺ decay. Since the half-life is 70.86 days, Co-58 generated during the operation of the reactor can be confirmed at the time of reactor shutdown and periodic inspection.

Mn-54 is a radionuclide generated by the (n, p) reaction of Fe-54 and emits γ-rays mainly having an energy of 835 keV by electron capture. Since the half-life is 312.1 days, Mn-54 generated during the operation of the reactor can be confirmed even when the reactor is shut down and during periodic inspections.
Fe-59 is a radionuclide generated by the (n, γ) reaction of Fe-58, and emits γ-rays mainly having energy of 1099 keV and 1292 keV by β ^- decay. Since the half-life is 44.5 days, Fe-59 generated during the operation of the reactor can be confirmed even when the reactor is shut down and during periodic inspections.

  Eu-152 and Eu-154 are radionuclides produced by the (n, γ) reaction of Eu-151 and Eu-153. It can also be confirmed as a fission product contained in the fuel rod in the reactor pressure vessel.

By electron capture and β ^- decay, Eu-152 emits gamma rays mainly having energy of 1408 keV and 122 keV, and Eu-154 mainly having energy of 1274 keV, 723 keV and 123 keV. Since the half-life is 13.54 years for Eu-152 and 8.593 years for Eu-154, Eu-152 and Eu-154 generated during the operation of the reactor are confirmed even when the reactor is shut down and at periodic inspections. it can.

Sc-46 is a radionuclide produced by the (n, γ) reaction of Sc-45, and emits γ-rays having energies of 889 keV and 1121 keV mainly by β ^- decay. Since the half-life is 83.79 days, Sc-46 generated during reactor operation can be confirmed even when the reactor is shut down and during periodic inspections.

Zn-65 is a radionuclide generated by the (n, γ) reaction of Zn-64 and the (p, n) reaction of Cu-65, and has energy of 1116 keV and 511 keV mainly by electron capture and β ⁺ decay. Gamma rays are emitted. Since the half-life is 244.3 days, Zn-65 produced during the operation of the reactor can be confirmed even when the reactor is shut down and during periodic inspections.

Cs-134 is a radionuclide generated by the (n, γ) reaction of Cs-133, and emits γ-rays mainly having energy of 605 keV and 796 keV by β ^- decay. Since the half-life is 2.065 years, Cs-134 generated during the operation of the reactor can be confirmed at the time of reactor shutdown and periodic inspection.

Ta-182 is a radionuclide generated by the (n, γ) reaction of Ta-181 and emits γ-rays having energy of 1121 keV and 1221 keV mainly by β ^- decay. Since the half-life is 114.4 days, Ta-182 generated during the operation of the reactor can be confirmed at the time of reactor shutdown and periodic inspection.

Nb-94 is a radionuclide generated by the (n, γ) reaction of Nb-93 and emits γ-rays mainly having energy of 871 keV and 703 keV by β ^- decay. Since the half-life is 2.03 × 10 ⁴ years, Nb-94 generated during the operation of the reactor can be confirmed even when the reactor is shut down and during periodic inspections.

  Cr-51 is a radionuclide generated by the (n, γ) reaction of Cr-50, and emits γ-rays mainly having an energy of 320 keV by electron capture. Since the half-life is 27.7 days, the Cr-51 generated during the operation of the reactor can be confirmed even when the reactor is shut down and during periodic inspections.

  The index nuclide at the rated operation of the reactor (the main nuclide at the rated time) is a radionuclide that is generated by the operation of the reactor and cannot be confirmed at the time of reactor shutdown and periodic inspection due to its short half-life. N-16, N-13, F-18, O-19, Mn-56 etc. are mentioned as an example of a rating main nuclide.

N-16 is a radionuclide generated by the (n, p) reaction of O-16, and emits γ-rays having energy of 6129 keV and 7115 keV mainly by β ^- decay. Since the half-life is 7.13 seconds, it is a nuclide whose existence can be confirmed only during reactor operation.

N-13 is a radionuclide generated by the (p, α) reaction of O-16, and emits γ-rays having energy of 511 keV mainly by electron capture and β ⁺ decay. Since the half-life is 9.96 minutes, it is a nuclide whose existence can be confirmed only during reactor operation.

F-18 is a radionuclide generated by the (p, n) reaction of O-18, and emits γ-rays having energy of 511 keV mainly by electron capture and β ⁺ decay. Since the half-life is 109.8 minutes, it is a nuclide whose existence can be confirmed only during reactor operation.

O-19 is a radionuclide generated by the (n, γ) reaction of O-18, and emits γ-rays mainly having energy of 197 keV and 1357 keV by β ^- decay. Since the half-life is 26.9 seconds, it is a nuclide whose existence can be confirmed only during reactor operation.

Mn-56 is a radionuclide produced by the (n, γ) reaction of Mn-55, the (n, p) reaction of F-56, the (n, α) reaction of Co-59, and the like by β ^- decay. Gamma rays having energy of 846 keV, 1810 keV and 2113 keV are mainly emitted. Since the half-life is 2.579 hours, it is a nuclide whose existence can be confirmed only during reactor operation.

  Most of the rated operation of nuclear reactors is conducted at the rated main nuclides such as N-16, N-13, etc., when the main nuclides such as Co-60 and Co-58 that can be confirmed at the time of reactor shutdown and periodic inspection Since it is lower than the intensity, it is difficult to measure the γ-ray peak derived from the main nuclide at the time of regular inspection on the γ-ray energy spectrum, and it is difficult to compensate the gain only by the main nuclide at the time of regular inspection.

  Moreover, since the major nuclides at the time of rating have a short half-life, most of them are attenuated at the time of reactor shutdown and periodic inspection, and it is difficult to confirm the presence with a general radiation detector. It is difficult to compensate for gain only with major nuclides.

  At the time of reactor start-up operation (at the time of reactor startup) and at the time of shutdown operation (at the time of reactor shutdown), the main nuclides at the regular inspection and the main nuclides at the time of rating are determined according to the reactor power and reactor operation status. Used as an indicator nuclide. Details are shown below.

  In the case of the reactor start-up operation, gain compensation is performed using main nuclides such as Co-60 and Co-58 at the time of the initial check-up. As the reactor power increases, the γ-ray intensity by the main nuclides at the time of rating such as N-16 and N-13 increases, so it becomes difficult to confirm the γ-ray peak by the main nuclides at the regular inspection.

  For this reason, before the gamma-ray peak due to the main nuclide at the regular inspection can no longer be confirmed, the index nuclide for gain compensation is changed to the main nuclide at the rated time. A gain compensation algorithm is needed.

  During the reactor shutdown operation, the procedure is the reverse of the reactor startup operation, and as the reactor power decreases, the gamma ray intensity due to the rated main nuclide decreases, so that the gamma ray peak due to the main nuclide at the regular inspection can be confirmed. It becomes.

  For this reason, the gain compensation index nuclide is changed to the main nuclide at the time of regular inspection before the gamma ray peak due to the rated main nuclide can no longer be confirmed. Gain compensation that selects the main index nuclide from two or more index nuclides An algorithm is needed.

  As described above, the radiation detector for measuring the radiation in the installation environment, the detector power supply of the radiation detector, the gain adjustment device capable of variably adjusting the output gain of the radiation detector, and the γ-ray energy spectrum from the output of the gain adjustment device A multi-channel wave height analyzer that calculates γ-ray peak center measured value of γ-ray peak on γ-ray energy spectrum, and the γ-ray peak center measured value and γ-ray calculated by the peak calculator Gain compensation for calculating the deviation from the peak center setting value, determining the gain compensation amount, and determining the gain adjustment amount for adjusting the deviation between the γ-ray peak center setting value and adjusting the gain of the gain adjustment device Equipped with a specific radionuclide (hereinafter referred to as regular inspection) that can be confirmed by the reactor power and reactor operation status when the reactor is shut down and during periodic inspections. The index nuclide for gain compensation is used as the index nuclide for gain compensation, and the specific nuclide that can be confirmed by the reactor power and reactor operation status Is used as an indicator nuclide for gain compensation, and during reactor start-up operation (at reactor startup) and shutdown operation (at reactor shutdown), depending on reactor power and reactor operation status, By using the main nuclides at the regular inspection and the main nuclides at the rated time as index nuclides, the gain of the radiation detector is compensated by using the index nuclides according to each reactor power and reactor operation status. Without using calibration radiation source, natural radioactive material, light source, and temperature information, it is possible to compensate for fluctuations in gain of the radiation detector according to the installation environment and measurement environment of the radiation detector such as reactor power and reactor operation status. .

  Next, a measurement environment compensation type radiation monitor and a gain compensation method thereof according to a preferred embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a basic configuration of a measurement environment compensation type radiation monitor 7 installed in a reactor containment vessel in a reactor building according to a first embodiment of the present invention.

  The measurement environment compensation type radiation monitor 7 of the first embodiment is installed inside a reactor containment vessel 9 housed in the reactor building 8, and includes a radiation detector 1 for measuring radiation in the installation environment, and the reactor. A detector power supply 15 that is installed outside the storage container 9 and supplies power to the radiation detector 1, a gain adjustment device 2 that variably adjusts the output gain of the radiation detector 1, and a gain adjustment device 2 Multichannel wave height analyzer 3 that calculates a γ-ray energy spectrum from the output of the signal, and a peak calculator that calculates a γ-ray peak center measurement value of the γ-ray peak on the γ-ray energy spectrum calculated by the multichannel wave height analyzer 3 4 and a peak discriminating device 5 for discriminating gain compensation by calculating a difference between the measured value of the γ-ray peak center calculated by the peak calculating device 4 and the set value of the γ-ray peak center, A gain compensator 6 that adjusts the gain of the gain adjusting device 2 by determining a gain adjustment amount for adjusting a deviation between the measured value of the γ-ray peak center calculated by the separate device 5 and the set value of the γ-ray peak center. Has been.

  The radiation detector 1 of the measurement environment compensation type radiation monitor 7 is connected to a detector power supply 15 and a gain adjustment device 2, respectively. The gain adjustment device 2 is connected to the multi-channel wave height analysis device 3 and the gain compensation device 6, respectively. It is connected.

  The multi-channel wave height analyzer 3 is connected to a peak calculator 4, the peak calculator 4 is connected to a peak discriminator 5, and the peak discriminator 5 is connected to a gain compensator 6.

  As an installation environment of the measurement environment compensation type radiation monitor 7, a nuclear power plant is exemplified as shown in FIG. The installation position of the measurement environment compensation type radiation monitor 7 is inside the reactor containment vessel 9 in the reactor building 8 of the nuclear power plant.

  The equipment in the reactor building 8 includes a reactor containment vessel 9 in which the reactor pressure vessel 10 is housed, and a main steam pipe for supplying steam generated in the reactor pressure vessel 10 to a steam turbine (not shown). 11, a water supply system pipe 12 for supplying condensate cooled by a steam turbine condenser to the reactor pressure vessel 10, and a reactor pressure vessel 10. There is a PLR pipe 14 that recirculates the material and a PLR pump 13 that is installed in the PLR pipe 14 and circulates the coolant.

  The main nuclides at the time of regular inspection of the nuclear power plant and the main nuclides at the time of rating are attached to piping, equipment and structures existing in the reactor building 8 or present in the primary coolant.

  FIG. 1 shows the configuration of a boiling water reactor as a nuclear power plant in which the measurement environment-compensated radiation monitor 7 of the first embodiment is installed, but a pressurized water reactor, a heavy water reactor, a graphite reactor, a fast reactor, which are similar light water reactors. The measurement environment compensation type radiation monitor 7 can also be applied to a breeding reactor, a gas cooling reactor, a molten metal cooling reactor, or a molten salt nuclear reactor.

  FIG. 2 to FIG. 4 show the γ-ray energy spectrum of the radiation according to the reactor output and the reactor operation status detected by the radiation detector 1 of the measurement environment compensation type radiation monitor 7 of this embodiment.

  FIG. 2 shows the γ-ray energy spectrum 17 of the radiation detected by the radiation detector 1 when the reactor is shut down and during the periodic inspection.

  In FIG. 2, as an example of the detected γ-ray energy spectrum 17 of radiation, γ by Co-60 existing in the reactor building 8 and pipes, equipment, structures, and primary system coolant existing in the reactor building 8. Line peak 16 was shown. Since the reactor is shut down, the gamma-ray energy spectrum from the main nuclides at the time of rating cannot be measured.

  FIG. 3 shows a γ-ray energy spectrum 18 of radiation detected by the radiation detector 1 during the reactor start-up operation and the reactor shutdown operation. In FIG. 3, as an example of the detected γ-ray energy spectrum 18, the main nuclide at the time of rating is N-16, and a γ-ray peak 19 of N-16 is shown.

  The single escape peak 20 and the double escape peak 21 due to electron pair generation can be measured by the interaction with the radiation detector 1. A γ-ray peak 16 due to Co-60 is also shown.

  Fig. 3 shows the γ-ray energy spectrum in the region where both the main nuclide at the time of regular inspection and the main nuclide at the rated time can be confirmed. However, during the reactor start-up operation, the strength of the N-16 rated nuclide gradually increases. The γ-ray peak due to the main nuclide cannot be confirmed at the regular inspection of Co-60.

  Further, during the reactor shutdown operation, the strength of the main nuclide at the N-16 rating gradually decreases, and the γ-ray peak due to the main nuclide at the N-16 rating cannot be confirmed.

  FIG. 4 shows a γ-ray energy spectrum 22 detected by the radiation detector 1 during the reactor rated operation. In FIG. 4, as an example of the detected γ-ray energy spectrum 22, the main nuclide at the time of rating is N-16, and the γ-ray peak of N-16 is shown. A single escape peak 20 and a double escape peak 21 due to electron pair generation can also be measured.

  During the reactor rated operation, the intensity due to N-16 is higher than the intensity due to the main nuclide at the time of the regular inspection, so the gamma ray peak due to the main nuclide at the time of the regular inspection cannot be confirmed.

  As shown in FIGS. 2 to 4, the γ-ray energy spectrum of the radiation detected by the radiation detector 1, respectively, the γ-ray energy spectrum and the γ-ray peak that can be measured by the radiation detector 1 depending on the reactor power and the reactor operation status. Is different. For this reason, it is necessary to compensate for the gain by using the index nuclide corresponding to the reactor power and the reactor operation status.

  FIG. 5 shows fluctuations in the γ-ray peak measured by the radiation detector 1 in the reactor power and reactor operating conditions when gain compensation is not performed. The γ-ray energy spectrum 18 during the reactor start-up operation and the reactor shutdown operation is indicated by a one-dot chain line, the γ-ray energy spectrum 22 during the reactor rated operation is indicated by a chain line, and the γ-ray energy spectrum during the reactor shutdown and during the periodic inspection 17 is indicated by a solid line.

  FIG. 5 shows fluctuations in the Co-60 γ-ray peak 16 and the N-16 γ-ray peak 19 due to temperature fluctuations, as an example of the measured fluctuations in the γ-ray peak.

  Since the temperature of the installation environment of the radiation detector 1 increases as the reactor starts, for example, when the radiation detector 1 to be used has a negative gain multiplication factor accompanying the temperature increase, the output level of the radiation detector 1 is The γ-ray energy is apparently reduced.

  Therefore, in order to compensate for this decrease in power level, that is, to compensate for the gain, the index nuclide is selected according to the reactor power and reactor operating conditions, and the γ-ray peak center measurement value of the index nuclide is set to the γ-ray peak center. Adjust to the value.

  A function for variably adjusting the output gain of the radiation detector 1 in the gain compensator 6 installed in the measurement environment compensation type radiation monitor 7 of the present embodiment will be described.

  FIG. 6 shows the relationship between the γ-ray peak fluctuation value of the index nuclide and the gain adjustment value. Here, the γ-ray peak fluctuation value is a difference between the measured value of the γ-ray peak center of the index nuclide and the set value of the γ-ray peak center, and is shown on the X axis in FIG. The gain adjustment value is a gain adjustment amount that makes the γ-ray peak fluctuation value almost zero, and is shown on the Y axis in FIG.

  In the gain compensator 6, the gain adjustment value is derived from the γ-ray peak fluctuation value by using the gain compensation function F (X) shown in FIG. The gain compensation function F (X) in FIG. 6 is a linear function as an example.

  This function is provided in the gain compensator 6, and by inputting the derived gain adjustment value to the gain adjuster 2, the output gain of the radiation detector 1 is variably adjusted to enable gain compensation.

  FIG. 7 shows the reactor power and the main nuclide index region for gain compensation in the reactor operation status.

  As shown in FIG. 7, the reactor power is 0% when the reactor is shut down and during periodic inspection. In this case, since it is the main nuclide index area 23 at the time of regular inspection, the index nuclide is the main nuclide at the time of regular inspection. Become.

  During the reactor start-up operation, the reactor power increases and enters the rated main nuclide index region 24 while the reactor power increases. Since there is a region where the main nuclide index region 23 at the time of regular inspection and the main nuclide index region 24 at the time of rating overlap, either the main nuclide at the time of regular inspection or the main nuclide at the time of rating can be selected as the index nuclide in this region.

  If the reactor power further increases, the main nuclide index region 23 at the time of the regular inspection exits, and the index nuclide at that time becomes the main nuclide at the time of rating.

  At the time of reactor rated operation, the indicator nuclide at the time of reactor rated operation is the main nuclide at the time of rating. Since the main nuclides at regular inspection are also generated during the operation of the reactor, the strength of the main nuclides at regular inspection increases.

  In the subsequent reactor shutdown operation, the main nuclide index region 23 is entered during the regular inspection when the reactor power decreases in the reverse procedure of the reactor startup operation. Since there is a region where the main nuclide index region 23 at the time of regular inspection and the main nuclide index region 24 at the time of rating overlap, either the main nuclide at the time of regular inspection or the main nuclide at the time of rating can be selected as the index nuclide in this region.

  When the reactor is shut down and when the periodic inspection is performed, the index nuclide becomes the main nuclide at the time of regular inspection because it is the main nuclide index region 23 at the time of regular inspection.

  Next, the gain compensation method of the measurement environment compensation type radiation monitor 7 of the present embodiment will be described.

  FIG. 8 shows a flowchart of the processing procedure of the gain compensation method of the measurement environment compensation type radiation monitor 7 of the present embodiment. The processing of the gain compensation method is performed by an apparatus included in the measurement environment compensation type radiation monitor 7. The gain compensation method by the measurement environment compensation type radiation monitor 7 of the present embodiment will be described along the flowchart of the processing procedure shown in FIG.

1 and 8,
Before starting the measurement of radiation by the radiation detector 1 of the measurement environment compensation type radiation monitor 7, the gain compensator 6 sets in advance the γ-ray peak center setting value of the γ-ray peak used for gain compensation (processing procedure). S1).

  Thereafter, the radiation measured by the radiation detector 1 is input to the multi-channel wave height analyzer 3, and a γ-ray energy spectrum is formed up to an arbitrary predetermined time (processing procedure S2).

  When the predetermined time has passed, the formation of the γ-ray energy spectrum in the multichannel wave height analyzer 3 is terminated (processing procedure S3).

  Next, the peak calculation device 4 searches for a γ-ray peak existing on the acquired γ-ray energy spectrum (processing procedure S4).

  Next, the peak calculation device 4 calculates a γ-ray peak center measurement value by γ-rays radiated from the index nuclide according to the reactor power and the reactor operation status (processing procedure S5).

  Next, the peak discrimination device 5 compares the preset γ-ray peak center set value with the measured γ-ray peak center measurement value to discriminate whether there is a significant deviation (processing procedure S6).

  If it is determined that there is a significant difference as a result of the determination by the peak determination device 5, the gain compensation device 6 calculates a gain adjustment amount that can adjust this deviation (processing procedure S7).

  Then, the gain adjustment device 2 is adjusted based on the gain adjustment amount calculated by the gain compensation device 6 to adjust the output gain of the radiation detector 1 (processing procedure S8).

  If there is no significant difference as a result of the determination by the peak determination device 5 in the processing procedure S6, and if the output gain of the radiation detector 1 is adjusted by the gain compensation device 6 in the processing procedure S8, the measurement is continued. (Processing procedure S9).

  And when continuing the measurement of the radiation by the radiation detector 1, it returns to process procedure S2, and a measurement is complete | finished otherwise (process procedure S10).

  The measurement environment compensated radiation monitor 7 of the present embodiment does not use the calibration radiation source, natural radioactive material, or light source and temperature information, and the installation environment and measurement of the radiation detector such as the reactor output and the reactor operation status. According to the environment, gain variation of the radiation detector can be compensated, and a highly accurate and highly reliable radiation monitor can be realized.

  Further, not only semiconductor detectors such as Si semiconductor detectors and Ge semiconductor detectors but also inexpensive scintillation detectors can be employed, which can contribute to cost reduction.

  As described above, according to the present embodiment, without using a calibration radiation source, a natural radioactive substance, or a light source and temperature information, it is caused by fluctuations such as temperature fluctuation, aging deterioration, or dose rate fluctuation of the radiation detector. It is possible to realize a radiation monitor used in a nuclear power plant and a radiation monitor gain compensation method that enables highly accurate measurement reflecting the detector operating characteristics.

  A measurement environment compensation type radiation monitor and its gain compensation method according to a second embodiment of the present invention will be described with reference to FIG.

  Since the configuration of the measurement environment compensation type radiation monitor installed in the reactor containment vessel in the reactor building in this embodiment is the same as that of the measurement environment compensation type radiation monitor 7 of the first embodiment shown in FIG. The description of the configuration common to both is omitted, and only the difference is described.

  In the measurement environment-compensated radiation monitor of Example 2, the main nuclide at the time of regular inspection is used as the index nuclide at the time of reactor shutdown and periodic inspection, and rated at the time of reactor start-up operation, reactor shutdown operation, and reactor rated operation. The measurement environment-compensated radiation monitor 7 of Example 1 is the same as the measurement environment-compensated radiation monitor 7 except that the time main nuclide and the main nuclide at the regular inspection are used as the index nuclide.

  Depending on the installation environment and the measurement environment of the radiation detector 1 of the measurement environment compensation type radiation monitor of the present embodiment, the intensity of the main nuclide at the regular inspection and the main nuclide at the time of rating differ. This depends on the piping and equipment in the reactor building 8 and the geometric arrangement of the structure and its structure.

  For this reason, even during the reactor rated operation as shown in FIG. 9, the γ-ray peak due to the main nuclide at the time of regular inspection may be measured on the γ-ray energy spectrum that can be obtained by the multichannel wave height analyzer 3.

  Therefore, when this condition is met, in the measurement environment compensation type radiation monitor of this embodiment, the main nuclide at the time of regular inspection is used as the index nuclide at the time of reactor shutdown and periodic inspection, and the reactor is shut down at the time of reactor start-up operation. During operation and reactor rated operation, the main nuclide at the time of rating and the main nuclide at the time of regular inspection are used as index nuclides, enabling gain compensation according to the radiation environment of the installation environment and measurement environment.

  The gain compensation method of the measurement environment compensation type radiation monitor of the present embodiment is the same as the flowchart of the processing procedure of the gain compensation method in the measurement environment compensation type radiation monitor 7 of the first embodiment shown in FIG. Omitted.

  As described above, according to the present embodiment, without using a calibration radiation source, a natural radioactive substance, or a light source and temperature information, it is caused by fluctuations such as temperature fluctuation, aging deterioration, or dose rate fluctuation of the radiation detector. It is possible to realize a radiation monitor used in a nuclear power plant and a radiation monitor gain compensation method that enables highly accurate measurement reflecting the detector operating characteristics.

  A measurement environment compensation type radiation monitor and its gain compensation method according to a third embodiment of the present invention will be described with reference to FIG.

  Since the configuration of the measurement environment compensation type radiation monitor installed in the reactor containment vessel in the reactor building in this embodiment is the same as that of the measurement environment compensation type radiation monitor 7 of the first embodiment shown in FIG. The description of the configuration common to both is omitted, and only the difference is described.

  In the measurement environment compensation type radiation monitor according to the third embodiment, the gain of the radiation monitor is compensated by combining the index nuclide for gain compensation at the time of reactor power reduction with the main nuclide at rated time and the main nuclide at regular inspection. Other than this, the measurement environment compensation type radiation monitor 7 of the first and second embodiments is the same as that of the first embodiment.

  During the rated reactor operation, a power suppression test (PST) for inspecting fuel leakage, hydrogen injection and noble metal injection (NMCA) to suppress stress corrosion cracking (SCC) of the reactor internal structure, etc. May be.

  When these processes are performed, depending on the installation position of the radiation detector 1, the strength of the main nuclide at the time of rating accompanying the decrease in the reactor output may occur. In this case, in the measurement environment compensation type radiation monitor of the present embodiment, the gain compensator 6 sets in advance a combination of the main nuclide at the rated time and the main nuclide at the time of the regular inspection, and the gain at the time when the reactor power is reduced. As shown in FIG. 10, the index nuclide for compensation is combined with the main nuclide at the time of rating and the main nuclide at the time of regular inspection, so that the gain of the radiation monitor can be compensated.

  The combination of the main nuclides at the time of rating and the main nuclides at the time of regular inspection is performed by calculating the peak calculating device 4 and the peak discriminating device 5 and adjusting the gain adjusting device 2 via the gain compensating device 6.

  In addition, as shown in FIG. 11, depending on the installation environment and measurement environment of the radiation detector 1, it may not be necessary to change the index nuclide for gain compensation when the reactor power is reduced.

  As described above, according to the present embodiment, without using a calibration radiation source, a natural radioactive substance, or a light source and temperature information, it is caused by fluctuations such as temperature fluctuation, aging deterioration, or dose rate fluctuation of the radiation detector. It is possible to realize a radiation monitor used in a nuclear power plant and a radiation monitor gain compensation method that enables highly accurate measurement reflecting the detector operating characteristics.

  FIG. 12 shows a basic configuration of the measurement environment compensation type radiation monitor 7 installed in the reactor containment vessel in the reactor building according to the fourth embodiment of the present invention.

  The measurement environment compensation type radiation monitor 28 of the fourth embodiment is installed inside the reactor containment vessel 9 stored inside the reactor building 8 and is a radiation detector 1a that measures radiation in two installation environments. 1b and the outside of the reactor containment vessel 9, respectively. The detector power supplies 15a and 15b for supplying power to the radiation detectors 1a and 1b, respectively, and the output gains of the radiation detectors 1a and 1b are variable. Gain adjusting devices 2a and 2b to be adjusted, multichannel wave height analyzers 3a and 3b for calculating a γ-ray energy spectrum from the outputs of the gain adjusting devices 2a and 2b, and γ rays calculated by the multichannel wave height analyzers 3a and 3b Peak calculation devices 4a and 4b for calculating a γ-ray peak center measurement value of the γ-ray peak on the energy spectrum, and the γ-ray peak calculated by the peak calculation devices 4a and 4b. The peak discriminating devices 5a and 5b for calculating the difference between the center measurement value and the γ-ray peak center setting value and discriminating the gain compensation, and the γ-ray peak center measurement value and the γ-ray calculated by the peak discriminating devices 5a and 5b Gain compensation devices 6a and 6b are provided for determining a gain adjustment amount for adjusting a deviation from the peak center set value and adjusting the gains of the gain adjustment devices 2a and 2b.

  When measuring radiation by a coincidence counting method or an inverse coincidence counting method as a general radiation measuring method in which a plurality of radiation detectors 1a and 1b have a correlation, the gain adjusting device 2a, A gate 25 that outputs a gate signal from the outputs of the plurality of radiation detectors 1a and 1b obtained by branching the output of 2b, and a multi-channel that forms a γ-ray energy spectrum by the gate signal output from the gate 25 A pulse height analyzer 27 and a scaler 26 for counting the gate signal of the gate 25 are provided.

  According to the measurement environment compensation type radiation monitor 28 having the above configuration, the gain is compensated for any of the plurality of radiation detectors 1a and 1b installed, and the correlation between the outputs of the radiation detectors 1a and 1b is obtained. By maintaining it, it is possible to maintain the measurement accuracy of the radiation detectors 1a and 1b that output the γ-ray energy spectrum by the gate signal.

  In the measurement environment compensation type radiation monitor 28 according to the fourth embodiment, N (N ≧ 2) or more radiation detectors 1a, 1b,..., 1n are used to output the output of any radiation detector 1a to another radiation detector. In the case of the radiation monitor 28 which is treated as a gate signal for 1b and acquires the γ-ray energy spectrum processed by the multichannel wave height analyzer 27 by the signal from the gate 25, the gain for any radiation detector 1a, 1b Is the same as that of the measurement environment compensation type radiation monitor of the first embodiment, the second embodiment, and the third embodiment, except that the correlation between the outputs of the radiation detectors 1a and 1b is maintained. is there.

  In the case of radiation monitors that perform high-precision measurements with N (N ≧ 2) or more radiation detectors 1a and 1b, many of them have a correlation with each output. Therefore, it is necessary to maintain high-accuracy measurement.

  When a simultaneous counting method, an inverse simultaneous counting method, or the like is performed as a radiation measurement method in which a plurality of radiation detectors 1a and 1b have a correlation, signals detected by the plurality of radiation detectors 1a and 1b are gain adjustment devices 2a and 2b. And the number of γ-rays is counted by the scaler 26, and is input from the gate 25 to the multichannel wave height analyzer 27 for processing.

  Therefore, in the measurement environment compensation type radiation monitor 28 of this embodiment, the multi-channel wave height analyzer 3a corresponding to the radiation detectors 1a and 1b is used for the γ-ray energy spectrum of each of the plurality of radiation detectors 1a and 1b. Compensates the gain without processing the γ-ray energy spectrum processed by the gate signal by calculating the γ-ray peak in 3b and compensating the gain by the index nuclide according to the reactor power and reactor operation status It is possible to maintain a highly accurate measurement.

  The gain compensation method of the measurement environment compensation type radiation monitor 28 of this embodiment is basically the same as the flowchart of the processing procedure of the gain compensation method in the measurement environment compensation type radiation monitor 7 of the first embodiment shown in FIG. Therefore, the description is omitted.

  As described above, according to the present embodiment, without using a calibration radiation source, a natural radioactive substance, or a light source and temperature information, it is caused by fluctuations such as temperature fluctuation, aging deterioration, or dose rate fluctuation of the radiation detector. It is possible to realize a radiation monitor used in a nuclear power plant and a radiation monitor gain compensation method that enables highly accurate measurement reflecting the detector operating characteristics.

  A measurement environment compensation type radiation monitor and its gain compensation method according to a fifth embodiment of the present invention will be described.

  In the measurement environment compensation type radiation monitor installed in the reactor containment vessel in the reactor building according to the present embodiment, instead of the γ-ray peak, the radiation detector 1 and the γ-ray incident on the radiation detector 1 are used. This is the same as the measurement environment compensation type radiation monitor 7 shown in the first to fourth embodiments except that gain compensation is performed using the Compton edge formed on the γ-ray energy spectrum by the Compton effect of the interaction. .

  In the case of using a radiation detector that has a low density such as an organic scintillator and takes a long time to form a γ-ray peak due to the photoelectric effect, the measurement environment-compensated radiation monitor of this example uses a γ-ray peak center measurement value and a γ-ray. By using the peak center set value as the Compton end measurement value and the Compton end set value, gain compensation can be performed and high-precision measurement can be maintained.

  A measurement environment compensation type radiation monitor and its gain compensation method according to a sixth embodiment of the present invention will be described.

  In the measurement environment compensation type radiation monitor installed in the reactor containment vessel in the reactor building according to the present embodiment, the γ-ray peak center measurement value of the γ-ray energy spectrum acquired by the multichannel wave height analyzer 3 is used. The measurement environment compensation type radiation monitor 7 shown in the first to fifth embodiments is the same as that of the first embodiment to the fifth embodiment except that the energy calibration of the γ-ray energy spectrum according to the reactor power and the reactor operation state is performed.

  Generally, energy calibration of a γ-ray energy spectrum is performed by fitting a plurality of obtained γ-ray peak center measurement values with a linear function or the like and deriving a calibration curve.

  The γ-ray energy radiated by the main nuclide at regular inspection is lower than the γ-ray energy emitted by N-16, which is a typical main nuclide at the time of rating, and therefore the error of energy calibration in the high energy region becomes large. There is a case.

  In this case, in the measurement environment compensation type radiation monitor of the present embodiment, high-accuracy energy calibration can be performed by deriving a calibration curve using an index nuclide corresponding to the reactor power and the reactor operation status. .

  As described in the measurement environment compensation type radiation monitor of the fifth embodiment and the sixth embodiment, in these embodiments, the calibration radiation source, the natural radioactive substance, or the light source and the temperature information are not used. The radiation monitor used in nuclear power plants and the gain compensation method of the radiation monitor that enable high-accuracy measurement reflecting the detector operating characteristics due to fluctuations such as temperature fluctuation, aging deterioration, or dose rate fluctuation of the radiation detector realizable.

  The present invention is applicable to a measurement environment compensation type radiation monitor that compensates for gain fluctuations of a radiation detector of a radiation monitor used in a nuclear power plant and a gain compensation method thereof.

  1, 1a, 1b: radiation detectors, 2, 2a, 2b: gain adjusting device, 3, 3a, 3b: multichannel wave height analyzer, 4, 4a, 4b: peak calculating device, 5, 5a, 5b: peak discrimination Device, 6, 6a, 6b: Gain compensation device, 7: Measurement environment compensation type radiation monitor, 8: Reactor building, 9: Reactor containment vessel, 10: Reactor pressure vessel, 11: Main steam pipe, 12: Water supply System piping, 13: PLR pump, 14: PLR piping, 15: Detector power supply, 16: γ-ray peak of Co-60, 17: γ-ray energy spectrum during reactor shutdown and periodic inspection, 18: Reactor startup Γ-ray energy spectrum during operation and reactor shutdown operation, 19: N-16 γ-ray peak, 20: single escape peak, 21: double escape peak, 22: gamma-ray energy during reactor rated operation Ghee spectrum 23: main nuclide index regions during periodic inspection, 24: main nuclide index regions at the rated, 25: gate 26: scaler, 27: multi-channel pulse height analyzer, 28: measurement environment compensation type radiation monitor.

Claims (9)

The radiation monitor used in the reactor building of the nuclear power plant includes a radiation detector that is installed in the reactor building and measures radiation in the installation environment, a detector power source of the radiation detector, and an output of the radiation detector Gain adjusting device capable of variably adjusting gain, multi-channel wave height analyzer for calculating γ-ray energy spectrum from output of gain adjusting device, and γ-ray peak on γ-ray energy spectrum calculated by multi-channel wave height analyzer A peak calculation device for calculating a measured value of γ-ray peak center, and a peak discriminating device for determining gain compensation by calculating a difference between the measured value of γ-ray peak center calculated by the peak calculating device and a set value of γ-ray peak center And a gain adjustment amount for adjusting a deviation from the γ-ray peak center setting value calculated by the peak discriminating device. And a gain compensation unit for adjusting the emission,
A radiation monitor characterized in that the measurement accuracy of the radiation detector is maintained by compensating the gain of the radiation detector. A radiation monitor for use in a nuclear reactor reactor building, a plurality of radiation detectors installed in the reactor building to measure radiation in a plurality of installation environments, and a plurality of detector power supplies of the radiation detector, Calculated by a plurality of gain adjusting devices capable of variably adjusting the output gain of the radiation detector, a plurality of multi-channel wave height analyzers for calculating a γ-ray energy spectrum from the output of the gain adjusting device, and the multi-channel wave height analyzer A plurality of peak calculation devices for calculating the γ-ray peak center measurement value of the γ-ray peak on the γ-ray energy spectrum, and the γ-ray peak center measurement value and the γ-ray peak center setting value calculated by the peak calculation device. A gain adjustment unit that adjusts the deviation between a plurality of peak discriminating devices that calculate deviation and determine gain compensation, and the γ-ray peak center setting value calculated by the peak discriminating device. Determining the emission adjustment amount and a plurality of gain compensation apparatus for adjusting the gain of the gain adjusting device,
A gate that outputs a gate signal from the outputs of the N radiation detectors obtained by branching the output of the gain adjusting device, and a multi-channel pulse height analysis that forms a γ-ray energy spectrum by the gate signal output from the gate A device and a scaler for counting the gate signal of the gate,
Compensating the gain for any of the multiple radiation detectors installed (maintaining the measurement accuracy of the gamma ray energy spectrum by the gate signal by maintaining the correlation of the output of each radiation detector) A radiation monitor characterized by A radiation detector that is used in the reactor building of a nuclear power plant and measures radiation in an installation environment; a detector power supply of the radiation detector; and a gain adjustment device that can variably adjust an output gain of the radiation detector; Multi-channel wave height analyzer for calculating γ-ray energy spectrum from output of gain adjusting device, peak calculating device for calculating γ-ray peak center measurement value of γ-ray peak on γ-ray energy spectrum, and peak calculating device A peak discriminating device for calculating a deviation between the γ-ray peak center measurement value and the γ-ray peak center setting value calculated in step 1 and determining a gain compensation, and a gain adjustment amount for adjusting a deviation between the γ-ray peak center setting value A gain compensation method for a radiation monitor comprising a gain compensation device that determines the gain and adjusts the gain of the gain adjustment device,
At the time of reactor shutdown and periodic inspection, a specific radionuclide that can be confirmed by the reactor power and reactor operation status (hereinafter referred to as the main nuclide during regular inspection) is used as an index nuclide for gain compensation.
For the indicator nuclide during rated reactor operation, the specific radionuclide that can be confirmed by the reactor power and reactor operation status (hereinafter referred to as the rated nuclide) is used as an indicator nuclide for gain compensation.
During reactor start-up operation and shutdown operation, depending on the reactor power and reactor operation status, the main nuclides at the regular inspection and the main nuclides at the rated time are used as index nuclides, respectively. A gain compensation method for a radiation monitor, wherein the gain of the radiation detector is compensated using an index nuclide. Used in a nuclear reactor building, a plurality of radiation detectors for measuring radiation in a plurality of installation environments, a plurality of detector power supplies for the radiation detector, and an output gain of the radiation detector are variable. A plurality of gain adjusting devices that can be adjusted, a plurality of multi-channel wave height analyzers that calculate a γ-ray energy spectrum from the output of the gain adjusting device, and a γ-ray peak on the γ-ray energy spectrum calculated by the multi-channel wave height analyzer A plurality of peak calculation devices for calculating a γ-ray peak center measurement value, and a plurality of determining a gain compensation by calculating a difference between the γ-ray peak center measurement value calculated by the peak calculation device and a γ-ray peak center setting value And determining the gain adjustment amount for adjusting the deviation between the peak discriminating device of the γ-ray and the γ-ray peak center setting value calculated by the peak discriminating device. And a plurality of gain compensation apparatus for adjusting the gain of the integer unit,
Furthermore, a gate that outputs a gate signal from the outputs of the N radiation detectors obtained by branching the output of the gain adjusting device, and a multi-channel wave height that forms a γ-ray energy spectrum by the gate signal output from the gate. A radiation compensation gain compensation method comprising: an analyzer; and a scaler that counts the gate signal of the gate,
At the time of reactor shutdown and periodic inspection, a specific radionuclide that can be confirmed by the reactor power and reactor operation status (hereinafter referred to as the main nuclide during regular inspection) is used as an index nuclide for gain compensation.
For the indicator nuclide during rated reactor operation, the specific radionuclide that can be confirmed by the reactor power and reactor operation status (hereinafter referred to as the rated nuclide) is used as an indicator nuclide for gain compensation.
At the time of reactor start-up operation and shutdown operation, depending on the reactor power and reactor operation status, the main nuclide at regular inspection and the main nuclide at rated time are used as index nuclides, respectively, depending on the reactor power and reactor operation status. The radiation monitor is characterized in that the measurement accuracy of the γ-ray energy spectrum by the gate signal is maintained by compensating for the gain of the radiation detector using the index nuclide and maintaining the correlation between the outputs of the radiation detectors. Gain compensation method. In the method for gain compensation of a radiation monitor according to claim 3 or 4,
At the time of reactor shutdown and periodic inspection, the main nuclide at the time of regular inspection is used as the index nuclide. A gain compensation method for a radiation monitor. In the method for gain compensation of a radiation monitor according to claim 3 or 4,
A gain compensation method for a radiation monitor, wherein a gain of a radiation detector is compensated by combining an index nuclide for gain compensation at the time of reactor power reduction with a main nuclide at rated time and a main nuclide at regular inspection .
In the method for gain compensation of a radiation monitor according to claim 3 or 4,
A gain compensation method for a radiation monitor, wherein gain compensation is performed using a Compton edge formed on a γ-ray energy spectrum by a Compton effect of interaction between the radiation detector and γ-rays incident on the radiation detector. In the method for gain compensation of a radiation monitor according to claim 3 or 4,
Radiation that performs energy calibration of the γ-ray energy spectrum according to the reactor power and reactor operating conditions using the measured value of the γ-ray peak center of the γ-ray energy spectrum acquired by the multichannel wave height analyzer Monitor gain compensation method. In the method for gain compensation of a radiation monitor according to claim 3 or 4,
The main nuclides at the time of regular inspection are Co-60, Co-58, Mn-54, Fe-59, Eu-152, Eu-154, Sc-46, Zn-65, Cs-134, Ta-182, Rh-106. , Nb-94, Cr-51, and the rated main nuclide is N-16, N-13, F-18, O-19, or Mn-56. Gain compensation method.

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