JP6768978B2 - Radiation detector - Google Patents

Description

The present invention relates to a radiation detector, for example, a radiation detector having a failure detection function of a component inside the radiation detector.

Conventionally, in nuclear power plants or facilities handling radioactive isotopes, in order to control radioactive substances contained in process fluids such as water or gas discharged used in the process, radiation incident from the outside is absorbed and light is emitted. A radiation detector using a plastic scintillator is used as a scintillator to convert to.

In this type of radiation detector, it is necessary to detect the failure of the radiation detector due to the importance of the radiation measurement, so a small RI (Radio Patent) radiation source called a live zero radiation source is inside the radiation detector. Is attached (see, for example, Patent Document 1). In some cases, a radiation source case provided with an RI radiation source is attached to the radiation detector, and radiation is incident on the radiation detector from the radiation source irradiation hole of the radiation source case.
The radiation emitted from these RI radiation sources is detected, and a certain amount of current can always be obtained in a healthy state. However, if the components that make up the radiation detector fail, the radiation emitted from the RI radiation source Can not be measured and a current above a certain level cannot be obtained. Therefore, a failure of the radiation detector can be detected by not detecting the current.

JP-A-59-63584

However, since the conventional radiation detector uses a small RI radiation source to detect a failure inside the radiation detector, the radiation detector is disassembled when the radiation detector is discarded, and the RI radiation source is used. It had to be removed and disposed of separately. Further, it is necessary to attach the RI radiation source to a predetermined position when assembling the radiation detector, and there is a problem that the number of components is increased as compared with the radiation detector having no failure detection function.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a radiation detector capable of reducing the management of RI radiation sources and the number of components when disposing of the radiation detector. And.

The radiation detector according to the present invention is between a scintillator that converts radiation into radiated light, a photomultiplier tube that outputs the radiated light emitted from the scintillator as a current pulse, and a photomultiplier tube between the scintillator and the photomultiplier tube. The scintillator has a light guide provided in the scintillator, a preamplifier that converts a current pulse output from the photomultiplier tube into a voltage pulse and amplifies the scintillator, and an opening for injecting radiation into the scintillator. A case for accommodating a component composed of a light guide, the photomultiplier tube and the front amplifier, and a fixing member containing a chemical that emits radiation and fixing the light guide to the case. In addition, the failure of the component is detected by detecting the radiation emitted from the fixing member.
Further, the radiation detector according to the present invention includes a scintillator that converts radiation into radiation, a photoelectron multiplier that outputs radiation emitted from the scintillator as a current pulse, and the scintillator and the photoelectron multiplier. The scintillator has a light guide provided between the two, a preamplifier that converts a current pulse output from the photoelectron multiplying tube into a voltage pulse and amplifies it, and an opening for injecting radiation into the scintillator. A case for accommodating components including the light guide, the photoelectron multiplying tube, and the pre-amplifier, and a radiation source irradiation hole provided in contact with the case and allowing radiation to enter the inside of the case. A radiation source case having a radiation source and a working plate provided inside the radiation source case and containing a chemical that emits radiation are provided, and the radiation emitted from the working plate is detected to detect the radiation. It detects the failure of component parts.

According to the radiation detector of the present invention, by using a chemical as a radiation source instead of the built-in RI radiation source, it is not necessary to remove the built-in RI radiation source and dispose of it separately when disposing of the radiation detector. The radiation detector is easy to handle. Further, since the chemicals are mixed and used with the fixing member for fixing the light guide, the number of parts constituting the radiation detector can be reduced. Furthermore, since the shape of the fixing member or the amount of chemicals used can be freely changed, the space inside the radiation detector can be effectively utilized. In addition, the amount of radiation emitted inside the radiation detector can be easily adjusted.

It is sectional drawing which shows the whole structure of the radiation detector in Embodiment 1 of this invention. It is sectional drawing which shows the whole structure of the radiation detector in Embodiment 2 of this invention.

Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings.
In each drawing, the same reference numerals are shown to be the same or equivalent.

Embodiment 1.
FIG. 1 is a cross-sectional view showing a radiation detector according to the first embodiment of the present invention. In addition, in FIG. 1, the arrow indicates the incident direction of radiation.
As shown in FIG. 1, the radiation detector 1 according to the first embodiment of the present invention uses a plastic scintillator 2 as a scintillator that absorbs radiation incident from the outside such as β rays 12 and converts it into light. There is. Further, the plastic scintillator 2 is bonded to the light guide 3 by an optical bonding material.

A reflective film 4 made of, for example, titanium oxide is coated on the inner side surface of the light guide 3, and is configured to efficiently guide the synchrotron radiation emitted from the plastic scintillator 2 to the photomultiplier tube 6. Further, on the radiation incident surface side of the plastic scintillator 2, a reflective sheet 5 made of, for example, an aluminum mylar is provided through a gap. The reflective sheet 5 reflects the synchrotron radiation emitted from the plastic scintillator 2 toward the radiation incident surface side opposite to the light guide 3 toward the light guide 3.

The light guide 3 is bonded to the photomultiplier tube 6 by an optical bonding material. The photomultiplier tube 6 converts the synchrotron radiation emitted from the plastic scintillator 2 into electrons, amplifies them, and extracts them as current pulses. Further, the preamplifier 7 converts the current pulse output from the photomultiplier tube 6 into a voltage pulse, amplifies it, and outputs it. The cable 8 sends the output signal output from the preamplifier 7 to a subsequent electronic circuit (not shown).

The detector case 9 has an opening for injecting radiation into the plastic scintillator 2, and houses a component configured including the plastic scintillator 2, a light guide 3, a photomultiplier tube 6, and a preamplifier 7. The plastic scintillator 2 and the reflective sheet 5 are arranged on the opening side of the detector case 9. Inside the detector case 9, for example, a cushion 10 made of an epoxy resin is provided in order to fix the light guide 3. Further, packing 11 is provided on the seal portion between the light guide 3 and the detector case 9 to keep the inside of the detector case 9 airtight.

The cushion 10 of the radiation detector 1 according to the first embodiment of the present invention is mixed with, for example, zirconium silicate as a chemical that emits radiation. A certain amount of radiation is emitted from zirconium silicate or the like contained in the cushion 10, and is converted into synchrotron radiation by the plastic scintillator 2. The synchrotron radiation is converted into electrons by the photomultiplier tube 6, amplified, and taken out as an electric signal. By monitoring this electric signal, it is possible to inspect the plastic scintillator 2 for damage, the photomultiplier tube 6 for failure, the cable 8 for disconnection, and the like.

The substance mixed in the cushion is not limited to zirconium silicate, but may be a commonly used chemical and emit a certain amount of radiation.
The radiation detector 1 according to the first embodiment of the present invention uses zirconium silicate, which is a general chemical, as a radiation source, so that the built-in RI radiation source is removed when the radiation detector 1 is discarded. It is not necessary to dispose of it separately, and the radiation detector 1 can be easily handled. Further, since zirconium silicate is mixed and used with the cushion for fixing the light guide 3, the number of parts constituting the radiation detector 1 can be reduced.

Furthermore, since the shape of the cushion 10 and the amount of zirconium silicate used can be freely changed, the space inside the radiation detector 1 can be effectively used, and the amount of radiation emitted inside the radiation detector 1 can be adjusted. It will be easy. As a result, according to the first embodiment of the present invention, the radiation detector 1 which is excellent in handling can be obtained.
In the radiation detector 1, the detection of radiation at a nuclear power plant or a facility handling radioactive isotopes can be confirmed when the instantaneous value of the current exceeds a specified value. On the other hand, the failure detection of the component components constituting the radiation detector 1 can be confirmed when the average value of the current falls below the specified value, and is distinguished from the detection of radiation.

Further, the radiation detector 1 in the first embodiment of the present invention uses a plastic scintillator 2 in which an organic luminescent material is dissolved in a plastic such as polystyrene as a scintillator, but a semiconductor member may be used as the scintillator. good. Specifically, as a member that converts radiation into light, for example, a semiconductor-type radiation detector 1 using a semiconductor made of silicon or germanium may be configured.

Embodiment 2.
FIG. 2 is a cross-sectional view showing the overall structure of the radiation detector according to the second embodiment of the present invention. Hereinafter, the configuration of the radiation detector according to the second embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 2, the radiation detector 1 according to the second embodiment of the present invention includes a radiation source case 23 having a radiation source irradiation hole 24 for incident radiation inside the detector case 9. It is provided in contact with the opening side of the. Further, inside the radiation source case 23, an operating plate 22 for adjusting the radiation amount is provided. In addition, the moving plate 22 contains a chemical that emits radiation. Then, the radiation emitted from the operating plate 22 passes through the radiation source irradiation hole 24 and is converted into an electric signal by the radiation detector 1. By detecting this electric signal, it is possible to detect a failure of a component inside the radiation detector 1.

Furthermore, the moving plate 22 can adjust the amount of radiation reaching the radiation detector 1 by changing the distance or the plate thickness from the radiation detector 1.
When radiation irradiation is not required, the working plate 22 can be rotated so as to be parallel to the radiation detector 1 to shield the radiation reaching the radiation detector 1.

The radiation detector 1 according to the second embodiment of the present invention includes a scintillator that converts radiation into radiation, a photoelectron multiplier 6 that outputs radiation emitted from the scintillator as a current pulse, and a scintillator and a photoelectron multiplier. It has a light guide 3 provided between the scintillator 6, a preamplifier 7 that converts the current pulse output from the photoelectron multiplier tube 6 into a voltage pulse and amplifies it, and an opening for injecting radiation into the scintillator. A case for accommodating components including a scintillator, a light guide 3, a photoelectron multiplying tube 6 and a front amplifier 7, and a radiation source irradiation hole provided in contact with the case to allow radiation to enter inside the case. A radiation source case 23 having 24 and an operating plate 22 provided inside the radiation source case 23 and containing a chemical that emits radiation are provided, and radiation emitted from the operating plate 22 is detected. Therefore, it is possible to detect the failure of the component parts.

Further, in the radiation detector 1 according to the second embodiment of the present invention, the plastic scintillator 2 or the semiconductor member may be used as the scintillator as in the first embodiment.
In the second embodiment of the present invention, the previously provided RI radiation source is reduced and the operating plate 22 is impregnated with a chemical that emits radiation, so that when the radiation detector 1 is discarded, the radiation detector 1 is disposed of. It is not necessary to remove the built-in RI radiation source and dispose of it separately, which has the effect of facilitating the handling of the radiation detector 1.

In the present invention, each embodiment can be freely combined, and each embodiment can be appropriately modified or omitted within the scope of the invention.

1 Radiation detector, 2 Plastic scintillator, 3 Light guide, 4 Reflective film, 5 Reflective sheet, 6 Photomultiplier tube, 7 Pre-amplifier, 8 Cable, 9 Detector case, 10 Cushion, 11 Packing, 12 β ray , 22 Working plate, 23 Source case, 24 Source irradiation hole

Claims (8)

A scintillator that converts radiation into synchrotron radiation,
A photomultiplier tube that outputs the synchrotron radiation emitted from the scintillator as a current pulse,
A light guide provided between the scintillator and the photomultiplier tube,
A preamplifier that converts the current pulse output from the photomultiplier tube into a voltage pulse and amplifies it.
A case having an opening for incidenting radiation into the scintillator and accommodating a component configured including the scintillator, the light guide, the photomultiplier tube, and the preamplifier.
A fixing member containing a chemical that emits radiation and fixing the light guide to the case.
A radiation detector characterized in that a failure of the component is detected by detecting the radiation emitted from the fixing member. The radiation detector according to claim 1, wherein the scintillator is a plastic scintillator or a semiconductor member. The radiation detector according to claim 1 or 2, wherein the fixing member is a cushion made of an epoxy resin. The radiation detector according to any one of claims 1 to 3, wherein the chemical is zirconium silicate. Any of claims 1 to 4, wherein a reflective sheet is provided which is detachably attached to the opening of the case and reflects synchrotron radiation emitted from the scintillator toward the light guide. The radiation detector according to item 1. The radiation detector according to any one of claims 1 to 5, wherein a reflective material film is applied to the inner side surface of the light guide. A scintillator that converts radiation into synchrotron radiation,
A photomultiplier tube that outputs the synchrotron radiation emitted from the scintillator as a current pulse,
A light guide provided between the scintillator and the photomultiplier tube,
A preamplifier that converts the current pulse output from the photomultiplier tube into a voltage pulse and amplifies it.
A case having an opening for incidenting radiation into the scintillator and accommodating a component configured including the scintillator, the light guide, the photomultiplier tube, and the preamplifier.
A radiation source case provided in contact with the case and having a radiation source irradiation hole for injecting radiation inside the case, and a radiation source case.
A working plate provided inside the radiation source case and containing a chemical that emits radiation is provided.
A radiation detector characterized in that a failure of the component is detected by detecting the radiation emitted from the moving plate. The radiation detector according to claim 7, wherein the chemical is zirconium silicate.

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