JP2023133004A - Self output type radiation detector, radiation detection system, and atomic reactor output monitoring device - Google Patents

Abstract

To provide a self output type radiation detector, a radiation detection system, and an atomic reactor output monitoring device that can be added to a narrow region in a detector and can detect leakage of an emitter to the outside of a container from a remote position without newly adding a signal line for detection.SOLUTION: A self output type radiation detector 1 includes: a metal emitter 2 for discharging electrons by irradiation of radiation; a heat-resistance container 3 for sealing the metal emitter 2; a metal collector 7 for containing the metal emitter 2 and the heat-resistance container 3 in the inside; a coaxial cable 30 for connecting the metal emitter 2 to a core wire 13 and connecting the metal collector 7 to a metal sheath 14; and a metal accumulator 12 electrically connected to the metal collector 7.SELECTED DRAWING: Figure 1

Description

The present invention relates to a self-output radiation detector that is a type of radiation detector, a radiation detection system equipped with the same, and a nuclear reactor output monitoring device.

As an example of a self-output type detector that can operate even if the emitter melts at high temperatures, Patent Document 1 describes a self-output type detector that has an emitter inside and a collector outside, with insulation between the emitter and collector. The type detector is equipped with an emitter container that encloses the emitter, and the emitter container is airtight, and when the emitter melts due to high temperature, the local emitter density within the emitter container is reduced regardless of the orientation of the self-output type detector. Self-powered detectors are described in which the emitter mass and the volume of the emitter vessel are adjusted to be constant.

JP2020-67312A

Self-output radiation detectors have a simple structure that does not require the application of voltage and measure the current generated when electrons are emitted from the emitter due to radiation, so they cannot be installed in relatively harsh environments. This is a radiation detector capable of

The emitter material of a self-output gamma ray detector, which is a type of self-output type detector, is preferably one that easily emits electrons when irradiated with gamma rays and has a small nuclear reaction cross section with neutrons. Pb and Bi exist as such elements, but these elements have low melting points and may deform or melt in a high-temperature environment such as inside a nuclear reactor. Similarly, in a self-powering neutron detector, if an element with a low melting point is used with priority given to the characteristics of the emitter, the emitter may be deformed or melted.

Patent Document 1 discloses a self-output type radiation detector that includes an emitter inside and a collector outside, and insulates between the emitter and the collector. A self-powering radiation detector is disclosed.

According to the self-output type radiation detector described in Patent Document 1, even if the emitter with a low melting point melts in a high-temperature environment, the emitter is retained in the container, so radiation measurement can be continued. .

However, unforeseen situations are also conceivable in which stress beyond expectations is applied to the heat-resistant container due to high-temperature environments, mechanical factors, etc., and the heat-resistant container is damaged. If the heat-resistant container were to break, depending on the degree of damage, the emitter material melted inside would leak to the outside of the container.

If the emitter leaks, the shape of the emitter within the detector changes significantly, which changes the ratio of the current value to the radiation, that is, the sensitivity, making it impossible to correctly convert the measured current value into the intensity of the radiation. Further, if the leaked emitter further leaks to the outside of the collector, the emitter material becomes foreign matter and diffuses into the environment outside the detector.

In order to avoid such a situation, it is effective to add a means for detecting leakage of the emitter material. For example, if it is possible to detect that the emitter material has leaked out of the container when a change occurs in the measured radiation value, it can be determined that the measured value by the detector is abnormal and not a change in the intensity of actual radiation. This is expected to improve the reliability of measured values.

However, if a large detection sensor is added to detect leakage of emitter material outside the container, the detector itself will become large, making it impossible to install the sensor in a narrow space such as inside a nuclear reactor. Measures are required.

Additionally, installing additional signal lines to receive the detection sensor signals from a remote location away from the site will incur costs for installation and additional cable penetrations, so there is room for improvement. will remain.

The present invention was made in order to solve the above-mentioned problems, and its purpose is to be able to be added to a narrow area inside the detector, and to be able to be added to a remote location without adding a new signal line for detection. An object of the present invention is to provide a self-output radiation detector, a radiation detection system, and a reactor output monitoring device capable of detecting leakage of an emitter to the outside of a vessel.

The present invention includes a plurality of means for solving the above problems, and to give one example, a metal emitter that emits electrons when irradiated with radiation, a heat-resistant container that seals the emitter, and a heat-resistant container that seals the emitter and A metal collector containing the heat-resistant container therein, a signal cable connecting the emitter to a positive electrode and the collector to a negative electrode, and a metal reservoir electrically connected to the collector. Features.

According to the present invention, the emitter can be added to a narrow area inside the detector, and leakage of the emitter to the outside of the container can be detected from a remote location without adding a new detection signal line. Problems, configurations, and effects other than those described above will be made clear by the description of the following examples.

1 is a configuration diagram of a self-output type radiation detector of Example 1. FIG. FIG. 7 is a modification of the self-output type radiation detector of Example 1, and is a diagram showing a second example of the shape of the metal reservoir. FIG. 7 is a modification of the self-output radiation detector of the first embodiment, and is a diagram showing a third example of the shape of the metal reservoir. FIG. 7 is a modification of the self-output type radiation detector of the first embodiment, and is a diagram showing a fourth example of the shape of the metal reservoir. FIG. 7 is a modification of the self-output type radiation detector of Example 1, and is a diagram showing a fifth example of the shape of the metal reservoir. FIG. 2 is a configuration diagram of a detection system according to a second embodiment. FIG. 3 is a configuration diagram of a detection system according to a third embodiment. The figure which showed the typical example of the reflection coefficient (rho) when TDR measurement is implemented with respect to a normal detector, and the reflection coefficient (rho) when there is a short circuit in a detector. FIG. 4 is a configuration diagram of a reactor power monitoring device according to a fourth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of a self-powering radiation detector, a radiation detection system, and a reactor power monitoring device of the present invention will be described below with reference to the drawings. In the drawings used in this specification, the same or corresponding components are given the same or similar symbols, and repeated description of these components may be omitted.

In the following explanation, a self-output type gamma ray detector will be mainly explained, but the same applies to a self-output type neutron detector. If a material with a large cross-sectional area for neutrons, a low probability of interaction with gamma rays, and a low melting point can be used as the emitter, self-powering neutron detection installed in a high-temperature environment such as a reactor can be achieved, as in Example 4 described later. It is promising as a vessel.

<Example 1>
Embodiment 1 of the self-output type radiation detector of the present invention will be described using FIGS. 1 to 5.

First, the overall configuration of a self-output type radiation detector will be described using FIG. 1. FIG. 1 is a configuration diagram of a heat-resistant self-output type radiation detector shown in this embodiment.

As shown in FIG. 1, the self-output type radiation detector 1 includes, at its center, a metal emitter 2 that emits electrons when irradiated with radiation and is sealed inside a substantially cylindrical heat-resistant container 3.

A metal terminal portion 4 and an airtight terminal 6 made of a ceramic base are attached to the lower part of the heat-resistant container 3.

The metal collector 7 includes the metal emitter 2, the heat-resistant container 3, and the airtight terminal 6 coaxially therein. Among these, insulating materials 10 and 11 are sandwiched between the heat-resistant container 3 and the metal collector 7 to insulate the heat-resistant container 3 and the metal collector 7, and to maintain a constant distance between the two. There is. Further, a tip end plug 8 is welded to the upper part of the metal collector 7, and a terminal end plug 9 is welded to the lower part, so that the inside of the metal collector 7 is sealed.

Furthermore, a coaxial cable 30 made of a core wire 13, a metal sheath 14, and an insulating material 15 for insulating between the core wire 13 and the metal sheath 14 is attached to the terminal end plug 9. Further, the core wire 13 is electrically connected to the metal terminal portion 4 of the airtight terminal 6, the metal sheath 14 is electrically connected to the metal collector 7, the metal emitter 2 is connected to the core wire 13, and the metal collector 7 is electrically connected to the metal collector 7. It is connected to a sheath 14 made of aluminum.

The metal reservoir 12 is made of metal, and is arranged and fixed below the metal emitter 2 in the vertical direction so as to be electrically connected to the metal collector 7 . The shape of the metal reservoir 12 is formed so as to coaxially cover the lower part of the heat-resistant container 3 and the outside of the airtight terminal 6.

The operation of the self-output type radiation detector 1 configured in this way will be described below.

When the self-output type radiation detector 1 of FIG. 1 is installed in a radiation environment, electrons are emitted from the metal emitter 2 by radiation irradiation. Some of the emitted electrons are absorbed by the metal emitter 2 again, but the remaining electrons are emitted to the outside of the metal emitter 2.

When electrons are emitted, the same amount of electrons as the emitted electrons flow into the metal emitter 2 via the core wire 13 of the coaxial cable and the metal terminal portion 4 of the airtight terminal 6 in order to balance the charges.

Here, since the number of electrons emitted per time from the metal emitter 2 is roughly proportional to the amount of radiation irradiated, the intensity of the irradiated radiation can be measured by measuring this flowing current.

If the self-powering radiation detector 1 is installed in a high-temperature environment, the metal emitter 2 may melt. However, since the molten metal emitter 2 is sealed in a heat-resistant container 3, its shape does not change significantly, and the number of electrons per unit emitted by radiation does not change significantly, so special measures must be taken. There isn't.

Next, an explanation will be given of the operation in the event that the heat-resistant container 3 is damaged due to a high-temperature environment or mechanical factors inside such a self-output type radiation detector 1.

When the metal emitter 2 sealed inside is melted, if the heat-resistant container 3 is damaged for some reason, the molten metal emitter 2 leaks to the outside of the heat-resistant container 3.

However, in the self-output type radiation detector 1 of this embodiment, the leaked metal emitter 2 accumulates in the gap between the metal reservoir 12 and the heat-resistant container 3. Since the metal reservoir 12 is electrically connected to the metal collector 7, at this time, the metal emitter 2 and the metal collector 7 are electrically short-circuited.

Then, the metal emitter 2 that has emitted electrons due to the radiation irradiation receives electrons from the short-circuited metal collector 7 instead of from the core wire 13 of the coaxial cable 30 in order to balance the charges. Therefore, leakage is detected when no current is generated in the core wire 13 and the measured current becomes almost zero.

On the other hand, in the case of a conventional heat-resistant self-output radiation detector that does not have a metal reservoir 12, if the metal emitter 2 leaks, the measured radiation value changes depending on the amount of leakage. It may become difficult to distinguish from changes in the radiation dose in the environment.

In this way, in this embodiment, when the metal emitter 2 leaks a certain amount, it short-circuits with the metal collector 7, and the measured value of radiation becomes zero, so that leakage is detected in a way that distinguishes it from changes in the radiation dose in the environment. be able to.

Next, a modification of the self-output type radiation detector of this embodiment will be described using FIGS. 2 to 5. 2 to 5 are diagrams showing modifications of the self-output type radiation detector.

The heat-resistant self-output type radiation detector 1A shown in FIG. 2 has a different shape of the insulating material 10A compared to the self-outputting type radiation detector 1 shown in FIG. It extends to around 9.

Further, an insulating material spacer 16 is provided below the airtight terminal 6 to fix the position of the heat-resistant container 3.

The metal reservoir 12 is attached to the metal collector 7 in the form of a disk just above the terminal end plug 9, that is, below the heat-resistant container 3, so as not to interfere with the stretched insulating material 10 and the insulating material spacer 16. There is.

In the self-output type radiation detector 1A, when the metal emitter 2 leaks from the heat-resistant container 3, it accumulates in the metal reservoir 12A through the gap between the insulating material 10A and the insulating material spacer 16, or through the inside of the insulating material spacer 16. As a result, the metal emitter 2 and the metal collector 7 are short-circuited, and leakage of the metal emitter 2 can be detected.

In the configuration example of the self-output type radiation detector 1 shown in FIG. 1, when the metal reservoir 12 is irradiated with radiation during radiation detection in a normal state, electrons are emitted from the metal reservoir 12, and the electrons are emitted from the metal reservoir 12. There is a risk that the electrons will be absorbed by the adjacent metal emitter 2, reducing the net number of electrons emitted by the radiation and reducing the generated current value. This means that the sensitivity decreases, but according to the configuration of FIG. 2, such a decrease in sensitivity can be minimized because the metal reservoir 12A is installed away from the metal emitter 2. , radiation can be measured with higher precision.

The configuration of yet another heat-resistant self-output radiation detector 1B shown in FIG. It is formed coaxially and arranged around the insulating material heat-resistant container 17. The end of the metal reservoir 12B is electrically connected to the metal collector 7.

Since the insulating material heat-resistant container 17 does not electrically short-circuit with the metal collector 7 even if it comes into contact with the metal reservoir 12B, the metal emitter 2 does not electrically short-circuit in a normal state.

According to the configuration of FIG. 3, even if the metal emitter 2 leaks from any part of the heat-resistant container 3, a small amount of leakage will contact the metal reservoir 12B and cause a short circuit with the metal collector 7. Therefore, compared to the configuration of FIG. 1, it is possible to detect less leakage.

The structure of yet another heat-resistant self-output radiation detector 1C shown in FIG. It is located. The metal reservoir 12C is formed into a disk shape and attached to the metal collector 7 directly below the airtight terminal 6 constituting one end of the insulating heat-resistant container 17.

If the metal emitter 2 leaks from the side or top of the insulating heat-resistant container 17, the metal emitter 2 and the metal collector 7 will electrically short-circuit and leak due to direct contact with the adjacent metal collector 7. can be detected. Further, if leakage occurs from the lower part of the airtight terminal 6, the metal emitter 2 and the metal collector 7 are short-circuited via the metal reservoir 12C, and the leakage can be detected.

According to the configuration of FIG. 4, the metal reservoir 12C and the insulating material 10 are not required between the insulating material heat-resistant container 17 and the metal collector 7, so the outer diameter of the detector can be reduced while realizing the leakage detection function. It becomes possible to do so. Therefore, it is possible to improve the reliability of radiation measurement in a more confined space.

The structure of yet another heat-resistant self-output radiation detector 1D shown in FIG. 5 is that in the structure of the self-output radiation detector 1C shown in FIG. This uses a material spacer 16 and a metal reservoir 18 made of metal mesh attached to its upper surface.

As described in the configuration example of FIG. 2, if there is a metal that emits electrons when irradiated with radiation in the vicinity of the metal emitter 2, the metal emitter 2 absorbs the emitted electrons, resulting in a measured current. The value decreases and the sensitivity of radiation measurements decreases.

In the configuration of FIG. 5, the metal reservoir 18 uses a metal mesh instead of a metal plate, thereby reducing electrons emitted from the metal reservoir 18 while maintaining the detection performance of the leaked metal emitter 2. It becomes possible not to reduce the sensitivity of radiation measurement.

Next, the effects of this embodiment will be explained.

The self-output radiation detectors 1, 1A, 1B, 1C, and 1D according to the first embodiment of the present invention described above include a metal emitter 2 that emits electrons when irradiated with radiation, and a metal emitter 2 that is sealed. A heat-resistant container 3, an insulating material heat-resistant container 17, a metal collector 7 that includes the metal emitter 2, the heat-resistant container 3, and the insulating material heat-resistant container 17 inside, and the metal emitter 2 are connected to the core wire 13, It includes a coaxial cable 30 that connects the metal collector 7 to the metal sheath 14, and metal reservoirs 12, 12A, 12B, 12C, and 18 that are electrically connected to the metal collector 7.

As a result, damage to the heat-resistant container caused by a high-temperature environment or mechanical factors can be detected from a remote location without increasing the size of the detector or adding a detection signal line. That is, when measuring radiation in a high-temperature, narrow place, it is possible to directly detect a measurement failure due to leakage of the metal emitter 2, and it is possible to distinguish between an original change in measured value and a failure. Therefore, the possibility that the metal emitter 2 leaking from the heat-resistant container 3 and the insulating heat-resistant container 17 further leaks from the metal collector 7 and diffuses as foreign matter outside the detector can be detected.

<Example 2>
A radiation detection system according to a second embodiment of the present invention will be described using FIG. 6. FIG. 6 is a configuration diagram of a detection system according to a second embodiment of the present invention.

A radiation detection system 40 shown in FIG. 6 uses the self-output radiation detector 1 shown in FIG. 1, and connects its core wire 13 and metal sheath 14 to a switch 19. The switch 19 is connected to a picoammeter 20 which is a measuring device for measuring minute direct current, and a resistance meter 21 for detecting a short circuit in the self-output radiation detector 1, and a control device 22 is attached. It is being

In the radiation detection system 40, when measuring radiation, the core wire 13 and the metal sheath 14 are connected to the picoammeter 20 by switching the switch 19 based on the control signal from the control device 22 to measure the current value according to the radiation. This is how radiation is measured.

In addition, when a radiation measurement value close to zero is observed, a control signal from the control device 22 connects the core wire 13 and the metal sheath 14 to the resistance meter 21 using the switch 19, that is, the resistance meter 21 and the self-output type radiation detector 1.

Thereby, by checking the resistance value of the resistance meter 21, it is possible to check whether there is a short circuit between the metal emitter 2 and the metal collector 7 of the self-output type radiation detector 1. Therefore, it is possible to determine whether the radiation in the environment actually has a value close to zero, or whether the radiation measurement value is close to zero due to a short circuit between the metal emitter 2 and the metal collector 7. .

Alternatively, when measuring in an area where the radiation dose in the environment is close to zero, the control device 22 may be used to switch the switch 19 to the resistance meter 21 side at regular intervals to periodically check the normal state of the detection system. good. This makes it possible to confirm that the detection system is always normal and that the radiation dose is close to zero.

Although FIG. 6 describes the case where the self-output type radiation detector 1 shown in FIG. 1 is used, the self-output type radiation detector used in the second embodiment is the self-output type radiation detector shown in FIG. The detector 1 is not limited to the detector 1, and any one of the self-output radiation detectors 1A, 1B, 1C, and 1D shown in FIGS. 2 to 5 can be used.

Since the radiation detection system 40 according to the second embodiment of the present invention includes the self-output type radiation detectors 1, 1A, 1B, 1C, and 1D according to the first embodiment described above, substantially the same effects can be obtained.

<Example 3>
A radiation detection system according to a third embodiment of the present invention will be described using FIGS. 7 and 8. Figure 7 is a configuration diagram of the detection system according to the third embodiment of the present invention, and Figure 8 shows the reflection coefficient ρ when TDR measurement is performed on a normal detector and the reflection coefficient ρ when there is a short circuit in the detector. FIG. 3 is a diagram showing a typical example.

A radiation detection system 40A shown in FIG. 7 uses the self-output type radiation detector 1 shown in FIG. 1, and its core wire 13 and metal sheath 14 are connected to a switch 19. The switch 19 includes a picoammeter 20, which is a measuring device for measuring minute direct current, and a TDR (time domain reflectometry) measurement device for detecting short circuits in the self-output radiation detector 1. A controller 23 is connected thereto, and a control device 22 is also attached.

Similarly to the second embodiment, in the radiation detection system 40A, the core wire 13 and the metal sheath 14 are connected to the picoammeter 20 by switching the switch 19 based on the control signal from the control device 22 when measuring radiation. Radiation is measured by measuring the current value.

Further, when a radiation measurement value close to zero is observed, the switch 19 is switched by a control signal from the control device 22 to connect the core wire 13 and the metal sheath 14 to the TDR measuring device 23. The TDR measuring device 23 confirms that the metal emitter 2 and the metal collector 7 are short-circuited inside the detector based on the reflection coefficient obtained by TDR measurement instead of the resistance value measurement with the resistance meter 21.

Below, a method for detecting that a short circuit has occurred inside the detector by TDR measurement will be explained using FIG. 8. The TDR measuring device 23 injects a step voltage toward the self-output type radiation detector 1 during measurement. The step voltage propagates within the coaxial cable 30 via the switch 19.

Here, if the characteristic impedance at each position of the coaxial cable 30 is Z _L and the characteristic impedance at the entrance of the coaxial cable is Z ₀ , the reflected voltage is returned from each position by multiplying the incident step voltage by the reflection coefficient ρ. . The reflection coefficient ρ is defined by the following equation (1).

That is, it can be expressed as the following equation (2).

The reflection coefficient ρ at each position is calculated by calculating the elapsed time after inputting the step voltage, the speed coefficient which is the ratio of the speed of the voltage propagating through the coaxial cable 30 to the speed of light, and the voltage at each time inside the TDR measuring device 23. It is evaluated by measuring it. As can be seen from the above equation (1), the reflection coefficient ρ becomes 0 at the position where Z _L and Z ₀ are equal.

Figure 8 shows the reflection coefficient ρ when performing TDR measurement on a normal detector with a velocity coefficient of 0.6, and the reflection coefficient when the metal emitter 2 and metal collector 7 are short-circuited in the detector. This shows a typical example of ρ.

In a normal state where the self-output type radiation detector 1 is not short-circuited, the metal emitter 2 and the metal collector 7 are close to each other, but are completely insulated. At this time, in the TDR measurement, the characteristic impedance _ZL becomes infinite at the position of the TDR measuring device 23, so the reflection coefficient asymptotically approaches 1.

On the other hand, when there is a short circuit inside the self-output type radiation detector 1, the characteristic impedance Z _L becomes 0, so the reflection coefficient asymptotically approaches -1. If this change in reflection coefficient occurs inside the self-output type radiation detector 1, it can be detected that a short circuit has occurred inside the self-output type radiation detector 1.

If the configuration of the radiation detection system 40 of Embodiment 2 is used, for example, a short circuit between the core wire 13 and the metal sheath 14 that occurs at the midpoint of the cable, and a short circuit that occurs inside the self-output type radiation detector 1. and cannot be distinguished.

However, if the configuration of the radiation detection system 40A of this embodiment using the TDR measuring device 23 is used, it is possible to distinguish between a short circuit that occurs at the midpoint of the cable and a short circuit that occurs within the detector, and detect the short circuit that occurs inside the detector. Due to the emitter leakage that occurs, it becomes possible to detect with high reliability that the metal emitter 2 and the metal collector 7 are short-circuited.

Although FIG. 7 also explains the case where the self-output type radiation detector 1 shown in FIG. 1 is used, the self-output type radiation detector used in the third embodiment is the self-output type radiation detector shown in FIG. The detector 1 is not limited to the detector 1, and any one of the self-output radiation detectors 1A, 1B, 1C, and 1D shown in FIGS. 2 to 5 can be used.

The radiation detection system 40A of the third embodiment of the present invention also provides substantially the same effects as the radiation detection system 40 of the second embodiment described above.

Further, since the short circuit detector is the TDR measuring device 23, it is possible to identify a short circuit within the self-output type radiation detector 1 or a short circuit at a different location, making it easier to deal with the problem.

<Example 4>
A nuclear reactor power monitoring device according to a fourth embodiment of the present invention will be explained using FIG. 9. FIG. 9 is a configuration diagram of a nuclear reactor power monitoring device according to a fourth embodiment of the present invention.

The reactor power monitoring device in FIG. 9 includes the radiation detection system 40A described in Embodiment 3, fission ionization chambers 104a, 104b, 104c, and 104d installed inside the in-reactor instrumentation tube 102, and the fission ionization chamber 104a. , 104b, 104c, and 104d, and an output monitoring device 107 that is connected to the self-output radiation detector 1 in the radiation detection system 40A and monitors the reactor output. .

Note that the radiation detection system 40 described in the second embodiment may be used instead of the radiation detection system 40A described in the third embodiment.

Four self-output radiation detectors 1 shown in FIG. A self-output radiation detector 1a, a self-output radiation detector 1b, a self-output radiation detector 1c, and a self-output radiation detector 1d) are installed.

It is assumed that the self-output type radiation detectors 1a, 1b, 1c, and 1d to be used are those shown in FIG. 1, but any of the self-output type radiation detectors 1, 1A, Any one or more of 1B, 1C, and 1D can be used in combination as appropriate.

The lower part of the in-core instrumentation tube 102 has a structure in which a water seal part 103 prevents the cooling water 110 in the reactor from flowing out. Each detector in the in-core instrumentation tube 102 is connected to a picoammeter 20 and a TDR measuring device 23 via a switch 19 equipped with a control device 22 by a coaxial cable 30.

In the in-core instrumentation tube 102, fission ionization chambers 104a, 104b, 104c, and 104d are installed at the same vertical height positions as the self-output radiation detectors 1a, 1b, 1c, and 1d, and these are connected to signal cables. 105, it is connected to a neutron flux monitor 106.

Further, an output monitoring device 107 is connected to the neutron flux monitor 106, the picoammeter 20, the control device 22, and the TDR measuring device 23.

The output monitoring device 107 monitors the reactor output by being connected to the neutron flux monitor 106 and calculates the sensitivity of the neutron detector 104 based on the measured value of the picoammeter 20.

Next, the operation of the reactor power monitoring device configured as described above will be explained. In the reactor power monitoring device of this embodiment, the neutron flux in the reactor generates current in the fission ionization chambers 104a, 104b, 104c, and 104d installed in the in-reactor instrumentation tube 102, and this current flows through the signal cable 105. The neutron flux is measured by the neutron flux monitor 106 via the neutron flux monitor 106. The neutron flux monitor 106 multiplies the measured current value by a constant set for each detector to convert it into a neutron flux value, and sends the neutron flux value to the output monitoring device 107.

The output monitoring device 107 evaluates the reactor output based on the input neutron flux value, confirms the health of the fuel based on this reactor output, and also performs scram etc. in response to abnormal changes in the reactor output at the time of an accident. Generates signals used to operate.

In parallel, a current corresponding to the radiation in the furnace flows through the coaxial cable 30 to the picoammeter 20 by the self-output radiation detectors 1a, 1b, 1c, and 1d, and the current value is measured. The picoammeter 20 multiplies the measured current value by the sensitivity set for each detector, converts it into radiation intensity, and sends the radiation intensity to the output monitoring device 107.

The output monitoring device 107 that has received the radiation intensity compares the neutron flux value sent out from the neutron flux monitor 106 and the radiation intensity sent out from the picoammeter 20, and calculates the amount of sensitivity deterioration due to irradiation of the neutron flux value. The constant for each detector built into the neutron flux monitor 106 is updated. Thereby, it is possible to correct the sensitivity which constantly deteriorates due to irradiation, and to always obtain a correct neutron flux value according to the current values of the fission ionization chambers 104a, 104b, 104c, and 104d.

Further, the output monitoring device 107 periodically outputs a command to switch to the TDR measuring device 23 side to the control device 22 connected to the switch 19. At the same time, a measurement command is sent to the TDR measuring device 23, and the self-power radiation detectors 1a, 1b, 1c, and 1d installed in the in-core instrumentation tube 102 are in a normal state by the operations shown in FIGS. 7 and 8. Check. If a short circuit is confirmed within the detector, the comparison between the radiation intensity from the detector and the neutron flux value from the neutron flux monitor 106 is interrupted, and the metal emitter 2 of the detector is is leaked.

With such an operation, the reactor power monitoring device shown in this embodiment can monitor the reactor power without using the measured value when the metal emitter 2 leaks, improving the reliability of monitoring. I can do it.

<Others>
Note that the present invention is not limited to the above-described embodiments, and includes various modifications. The above-mentioned embodiments have been described in detail to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described.

Further, it is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is also possible to add, delete, or replace some of the configurations of each embodiment with other configurations.

1, 1A, 1B, 1C, 1D, 1a, 1b, 1c, 1d...Self-output radiation detector 2...Metal emitter 3...Heat-resistant container 4...Metal terminal portion 6...Airtight terminal 7...Metal collector 8...Tip End plug 9...Terminal end plug 10, 10A...Insulating material 11...Insulating material 12, 12A, 12B, 12C, 18...Metal reservoir 13...Core wire (positive electrode)
14...Metal sheath (negative electrode)
15...Insulating material 16...Insulating material spacer 17...Insulating material heat-resistant container 19...Switch 20...Picoammeter 21...Resistance meter 22...Control device 23...TDR measuring device 30...Coaxial cable (signal cable)
40, 40A... Radiation detection system 101... Pressure vessel 102... In-core instrumentation tube 103... Water seal section 104a, 104b, 104c, 104d... Nuclear fission ionization chamber (neutron detector)
105...Signal cable 106...Neutron flux monitor 107...Output monitoring device 110...Cooling water

Claims (11)

A metal emitter that emits electrons when irradiated with radiation,
a heat-resistant container that seals the emitter;
a metal collector containing the emitter and the heat-resistant container therein;
a signal cable connecting the emitter to a positive pole and connecting the collector to a negative pole;
A self-output type radiation detector comprising: a metal reservoir electrically connected to the collector. The self-powering radiation detector according to claim 1,
The self-output type radiation detector, wherein the metal reservoir is formed in a disc shape below the heat-resistant container. The self-powering radiation detector according to claim 1,
The self-output type radiation detector, wherein the metal reservoir is arranged around the heat-resistant container. The self-powering radiation detector according to claim 2,
The heat-resistant container is made of an insulating material,
The self-output type radiation detector, wherein the metal reservoir is coaxially formed so as to cover a side surface of the heat-resistant container. The self-powering radiation detector according to claim 1,
The heat-resistant container is made of an insulating material,
The collector is arranged to surround the heat-resistant container with a gap between the collector and the heat-resistant container,
The self-output type radiation detector, wherein the metal reservoir is formed in a disc shape below the heat-resistant container. The self-powering radiation detector according to claim 1,
The self-output radiation detector is characterized in that the metal reservoir is formed of a metal mesh formed in a disk shape below the heat-resistant container. The self-powering radiation detector according to claim 1,
The self-output type radiation detector, wherein the metal reservoir is arranged below the emitter in the vertical direction. A self-output radiation detector according to any one of claims 1 to 7,
a control device;
switch and
Picoammeter and
A short circuit detector in the self-output radiation detector,
A radiation detection system characterized in that, by switching the switch by the control device, either the picoammeter or the short-circuit detector is switched to be connected to the self-output type radiation detector. The radiation detection system according to claim 8,
A radiation detection system characterized in that the short circuit detector is a resistance meter or a TDR measuring device. The radiation detection system according to claim 8,
an output monitoring device that is connected to the self-output radiation detector in the radiation detection system and monitors the reactor output;
A nuclear reactor output monitoring device, wherein the self-power radiation detector is installed inside an in-core instrumentation tube in a pressure vessel of a nuclear reactor. The reactor power monitoring device according to claim 10,
a neutron detector installed inside the in-core instrumentation tube;
further comprising a neutron flux monitor connected to the neutron detector,
The power monitoring device monitors the reactor power by being connected to the neutron flux monitor, and calculates the sensitivity of the neutron detector based on the measured value of the picoammeter. Device.

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