JPS6069797A - Pressure-sensitive type monitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical field to which the invention pertains] The present invention relates to safeguard technology for preventing theft of nuclear material, in which nuclear material is placed in a sealed container and the state of the container is monitored and recorded. This invention relates to a pressure-sensitive monitoring device using containment monitoring technology that ensures that the amount of nuclear material measured when inserting nuclear material into a sealed container has not changed, assuming that the container has not changed in any way.

[Prior art and its problems]

Securing means preventing the theft of nuclear material, or
Please notify us immediately that the item has been stolen.

This is a precautionary measure to prevent nuclear fuel from being misused.

This safeguard consists of metrological control, containment monitoring, and physical shredding.

Accounting management involves taking inventory from time to time, measuring the amount of inventory, taking into account all the inflows and outflows of nuclear material during that time, and calculating the material balance.
By determining the amount of missing nuclear material, the aim is to determine whether or not nuclear material was stolen. In addition to this measurement control, it is also used for criticality control and process control.

Physical barriers are measures to detect or prevent nuclear materials from being stolen. Technologies for this purpose include monitoring entrances and exits with television cameras, metal detectors, and radiation monitors, which are used to monitor intrusion by suspicious persons and to prevent nuclear materials from being illegally taken out. It is something to do.

Containment monitoring involves confining nuclear material in a sealed container, monitoring this container, and ensuring that the container remains unchanged to ensure that the amount of nuclear material measured before containment has been maintained to date. be.

Traditionally, sealed containers were monitored using a film camera, and a seal made of paper or wire was placed over the container and lid, and if this seal remained intact, the roundness changed. The company used a method of using no collateral as collateral.

However, when using a film camera, it is necessary to take out the film, develop it, and play it again, which places a burden on both the facility and the inspector. It is not suitable for

Also, when it comes to stickers made of paper or wire.

Occasionally, it is necessary to check on the condition of the seals, but generally the material storage has high radiation 6p levels and is not suitable for human access. Furthermore, as the scale of nuclear material handling facilities increases, the number of containers and seals that must be checked also increases, creating a heavy burden on facility operators and inspectors.

Therefore, online seals have been devised to replace these seals, allowing the status of the seals to be checked at any time from a remote location, but as long as these signals use electrical signals, they cannot be tampered with.
The proofability was low, and a forged signal could easily be inserted from an intermediate signal line, making it impossible to obtain sufficient reliability.

[Purpose of the invention]

The present invention eliminates the above-mentioned inconveniences and makes it easy for both facility operators and inspectors to verify containment.
The purpose of the present invention is to provide nuclear material monitoring equipment that allows inspectors to confirm seals without exposing them to radiation, and is also highly tamper-proof.

[Summary of the invention]

To achieve this objective, the present invention provides for measuring the weight of a sealed container in which nuclear material is sealed;7. This signal is converted into an optical signal that is difficult to forge, and is sent to a recording device and recorded. By monitoring this record, this pressure-sensitive monitoring device is configured to ensure that the nuclear material sealed in the container has not been stolen, based on the fact that there is no change in the weight.

〔Effect of the invention〕

In general, when attempting to remove nuclear material from a sealed container,
The lid must be opened or the container destroyed.

In addition, nuclear material storage containers are generally made to be fairly durable and have heavy lids, taking into consideration the reduction of radioactivity levels and the difficulty of repair in the event of damage. Therefore, when nuclear material is removed from such a container, the weight of the container inevitably changes considerably. Moreover,
It is not easy to remove the container because there is some vermin stuck under the container.

Therefore, according to the present invention, since the weight of the container is measured, it is possible to detect the theft of nuclear material without fail.

Furthermore, since the signal from the pressure sensitive element is transmitted as an optical signal over an optical fiber, any tampering of the signal line will always leave a record.

From the above, the device according to the present invention has extremely high tamper-proof properties and reliable theft detection ability, and theft can be monitored by looking at the records of a recorder located far away from the nuclear material container. By collecting and monitoring a large number of records in one place in a place with low radioactivity levels, it is possible to easily monitor all containers containing nuclear material without exposing people to radiation, reducing the burden on inspectors and facilities. can be significantly reduced.

[Embodiment of the Invention] Hereinafter, an embodiment of a pressure-sensitive monitoring device constructed according to the present invention will be described in detail.

transmitting pressure to a pressure sensitive element configured in accordance with the present invention;
The pressure transmitter 1 is placed under the nuclear material containment vessel to be monitored, and the pressure generated by the weight of the vessel is converted into silicon oil pressure, which is transmitted to the pressure-to-light converter 2, which converts the pressure to light. Converter 2 is.

Convert the pressure into intensity and put it on the optical fiber 3,
The weight value is transmitted to the weighing value calculator 4. Here, after converting the signal into an electrical signal, the values coming from the three measuring instruments are summed to calculate the military force of the container. This value is recorded on the data recorder 5. This recorder is of a type that records every analog value on paper using a pen.

On the other hand, all the differentials of the weighing values are calculated simultaneously using n and 4 vessels,
When the absolute value of this value exceeds a threshold value, a trigger signal is sent to turn on the power of the video camera 6 K, and the on/off state of the trigger signal is recorded in the recorder 5. In response to this trigger signal, the video camera 6 records the area around the nuclear material storage container being monitored and records it on the video deck 7.

As explained above, the present device Iζ is configured to monitor the weight of the nuclear material storage container and record a video if this value changes.

Next, the (?y configuration) of the pressure-light converter is shown in Figure 882.

As shown in Figure 2 (al), the configuration of this device is to convert the pressure transmitted by the pressure transmission pipe 1 into an electrical signal using a piezoelectric pressure sensor 2a, and to convert this signal into an optical signal. It consists of a voltage to optical signal conversion circuit 2b and a shield 2C for protecting these elements from radiation.

In particular, FIG. 2(b) shows a voltage-optical signal conversion circuit 2b. This circuit consists of a charge amplifier 10 to lower the impedance of the voltage Vin(t) from the pressure sensitive resistor.
and a circuit 11 for driving a photodiode.

Next, FIG. 3 shows the appearance of the storage box 9 for storing the arithmetic unit recorder, power supply, etc. of this device. This box is made of steel and has a door 9a with a glass window 9b and a key 9c. Furthermore, in order to leave a record in case the sides of the box are torn, a heat-shrinkable shrink seal is fixed on the inside of the box at the corner of the box.
It is crucifixion.

FIG. 4 shows how the pressure receiving element 1 is installed when this device is used to monitor a nuclear material storage container.

In FIG. 2(a), the pressure receiving element 1 is installed under the container 12. Moreover, in (b), it is installed under the lid 13. In case (b), the container is completely inside the hole and it is sufficient to monitor the lid.

In these examples, the container 12 is made of stainless steel, and the lid 13 is made of heavy concrete wrapped in stainless steel and is sufficiently heavy. Moreover, since a large external force is required for destruction, these operations are always detected as changes in weight.

In the monitoring device shown in this embodiment, the pressure sensitive part itself is extremely difficult as mentioned above, and the signal transmission path itself is an optical cable,
The signal will always be interrupted at some point, and it will be recorded. It is also possible to remotely monitor multiple containers and refrigeration units at the same time.
It is a conventional and excellent monitoring device.

[Brief explanation of drawings]

j:P Figure 1 shows the configuration 1ffi of the embodiment of the pressure-sensitive monitoring device according to the present invention, Figure 2 shows the configuration of the pressure-optical signal converter 114 of this embodiment, and Figure 3 shows the configuration of the storage box (74 structure). The perspective view shown in Figure 4 is a cross-sectional view showing the usage status of this device. ■ - Pressure receiver, pressure transmitter, 2... Pressure-light converter, 3 - Optical fiber, 4... Arithmetic unit. , 5. Recorder, 6. Video camera, 7. Video recorder, 8. Power supply, 9. Storage box, 10. Charge amplifier. 11. Voltage-light signal conversion circuit, 12. Nucleus. Material storage container, 13. Lid, 14. Nuclear material, 15. Handle, 16. Floor.

Claims (1)

[Claims] In containment monitoring technology, which is part of safeguards technology to prevent theft of nuclear materials, there is a pressure detection terminal that outputs a pressure signal as an optical signal, an optical fiber that transmits all the optical signals, and a pressure detection terminal that receives this signal and detects the pressure signal. It is equipped with a circuit that calculates a weight value from a container, a recorder that records this weight value, and an airtight container that houses the calculation circuit and recorder and prevents interference with the operation from outside, and that constantly stores nuclear material. A pressure-sensitive monitoring device characterized in that it is configured to monitor nuclear material in a sealed container by monitoring the weight of the container, and to record the situation.