JPS5916680B2 - radioactive material storage container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a double-structured storage container for radioactive substances such as radioactive exhaust gas, and in particular to a storage container in which the presence or absence of leakage of radioactive gas, etc. can be detected from changes in the internal pressure of the outer cylinder. It is.

BACKGROUND ART Conventionally, double-structured storage containers have been widely used in which an inner cylinder filled with radioactive substances such as radioactive exhaust gas is housed in an outer cylinder, and the outer cylinder is completely sealed by welding or the like.

By the way, if a leak occurs for some reason in a storage container for this type of radioactive material, conventionally,
It is difficult to detect this, and even if a helium leak detector is used, for example, if a large number of storage containers of this kind are stored in a storage room, it is possible to remotely control the helium leak detector to detect leaks. However, there are problems in that remote control is difficult, and the cost of equipment increases considerably.

Another possible method is to attach a pressure detector that can detect changes in internal pressure to the outer cylinder, and use the pressure detector to detect the presence or absence of a leak from changes in the internal pressure. It is necessary to install pressure detectors both inside and outside, and there is a risk that the pressure detectors themselves may become a source of leakage.

Therefore, the present invention provides a leak detection device for detecting radioactive materials that can easily and reliably detect the presence or absence of such leakage from the outside of the outer cylinder without making any extensive changes to the sealing structure of the outer cylinder itself. Its basic purpose is to provide a storage container.

Therefore, in the radioactive substance storage container according to the present invention, a differential pressure sensor is supported in the space between the outer cylinder and the inner cylinder, and the sensor is displaceable due to pressure changes in the space. The basic feature is that a detection sensor is provided on the outer wall side of the outer cylinder corresponding to the support position of the differential pressure sensor, and the presence or absence of a leak is detected from the pressure change in the inner pressure of the outer cylinder.

The differential pressure sensor according to the present invention includes a mercury-filled U-tube type differential pressure sensor with a magnet as a float (detector), a bellows or Lubutture disk type differential pressure sensor filled with gas, and a ferromagnetic magnet. Various conventionally known differential pressure sensors can be used, such as a differential pressure sensor equipped with a resonant circuit whose resonance frequency changes depending on the position of the body or ferroelectric material. Depending on the situation, a magnetic force detection device or an oscillation circuit depending on the resonance circuit can be used.

Hereinafter, the present invention will be described in more detail with reference to examples of the present invention.

In Fig. 1, 1 is a double-structured radioactive material storage container consisting of an inner cylinder 2 and an outer cylinder 3, and the inner cylinder 2 is filled with radioactive substances such as radioactive exhaust gas through the injection port 5 by opening the valve 4. Then, the valve 4 is closed, and then the upper part of the outer cylinder 3 made of a non-magnetic material is completely sealed by welding or the like, so that the inner cylinder 2 is completely shielded.

On the other hand, 6 is a well-known U-tube type differential pressure sensor supported by support seats 8, 8 provided on the inner wall 3a of the outer cylinder at approximately the vertical center of the space 7 between the inner cylinder 2 and the outer cylinder 3. , using the magnet 9 as a float, the sealing pressure P on the closed end 10a side of the U-shaped tube 10 is
The magnet 9 is displaced in response to the fluctuation ζ of a fluid such as mercury that moves up and down in accordance with the differential pressure between the pressure P and the internal pressure P of the outer cylinder acting from the open end 10b side.

In this case, the outer cylinder 3 is sealed so that the internal pressure P of the outer cylinder becomes a preset pressure Ps, and the outer wall 3b of the outer cylinder 3 is placed in a position corresponding to the position of the magnet 9 as a float determined by this.
A magnetic field measurement sensor 11 is attached to the side.

As this magnetic field measuring sensor 11, a sensor used in a well-known magnetic field measuring instrument can be used. Make it.

In the above configuration, a leak occurs in the outer cylinder 3 or the inner cylinder 2 for some reason, and as a result, the outer cylinder internal pressure P becomes the set pressure Ps.
, the magnet 9 is displaced in the vertical direction according to the change.

This displacement of the magnet 9 relative to the magnetic field measuring sensor 11 is detected as a change in the magnetic field by the magnetic field measuring sensor 11, and the measuring device main body 12 displays the measurement result to notify the supervisor that the pressure inside the outer cylinder has changed. be able to.

In the embodiment shown in FIGS. 2 and 3, a bellows 1 is filled with a gas having a pressure equal to the set value Ps of the external cylinder internal pressure.
5 or the base of a known lubricant disc 16 is fixed to the body of the inner cylinder 2 from the horizontal direction, and the movable end 15 of the bellows 15 is
A or the free piston 17 of the loveture disk 16 supports a magnet 18 as a detector, while a magnetic field measurement sensor 11' is supported at a corresponding position on the outside of the outer cylinder 3, and the outer cylinder internal pressure P is changed from the set value Ps. When the internal pressure changes, the change in internal pressure is outputted to the measuring instrument main body 12' via a connection 13' as a magnetic field change corresponding to a change in the distance between the magnet 18 and the magnetic field measurement sensor 11'. .

In addition, the embodiment shown in FIG. 4, for example, measures the internal pressure in the outer cylinder of a ferromagnetic material 9 as a float (detector) of a differential pressure sensor 6 using a U-shaped tube 10 similar to the embodiment shown in FIG. The positional change accompanying the change is extracted as a change in inductance.

That is, a resonant circuit 22 in which a coil 20 and a capacitor 21 are arranged in parallel surrounding the ferromagnetic material 9 side of the U-shaped tube 10 is attached to the U-shaped tube 10, while the outside of the outer cylinder 3 corresponding to the resonant circuit 22 is An oscillation circuit 26 in which a parallel coil 23 and a capacitor 24 are connected to an oscillator 25 is provided at the same position, and the oscillation frequency of the oscillator 25 is varied to adjust the inductance change of the resonant circuit 22 due to the change in the position of the ferromagnetic material 9. to change (
Therefore, the change in the output of the oscillator is detected by the detector 2T.

In addition, in the above-mentioned resonance circuit 22, the ferromagnetic material 9 as a float is displaced with respect to the coil 20, but the fifth
As shown in the figure, the capacitance may be changed by moving the ferroelectric material 9' forward and backward between a pair of electrode plates constituting the capacitor.

Note that for each of the embodiments shown in FIGS. 2 to 5, the first
Components that are the same as those in the embodiment shown in the figures are given the same numbers and their explanations are omitted.

As is clear from the above-described embodiments, the present invention provides a differential pressure sensor in which a detector is supported to be displaced in accordance with changes in the internal pressure of the outer cylinder inside the outer cylinder, and a support position of the differential pressure sensor. A detection sensor that detects the displacement of the above-mentioned detector is installed at a position outside the outer cylinder corresponding to the above, and when the internal pressure of the outer cylinder changes from the set pressure due to a leak, this can be detected and a warning of the existence of a leak can be issued. The present invention provides a storage container with an energy leakage detection device.

Therefore, according to the present invention, a leak in the outer cylinder or the inner cylinder can be easily detected without contacting the outer cylinder, and the presence of a leak can be reliably confirmed outside the storage chamber.
Unlike conventional systems, there is no need to remotely control the detection device, and the supervisor can simply turn on and off a switch in the monitoring room to detect the presence or absence of a leak and the storage container causing the leak. be able to.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5 are axial vertical cross-sectional explanatory views showing radioactive material storage containers according to embodiments of the present invention. 1...Storage container, 2...Inner cylinder, 3...
...Outer cylinder, 6...U-shaped tube type differential pressure sensor, 9
...Magnet or ferromagnetic material, 9'...Ferroelectric material, ii, 1i'... Magnetic field measurement sensor, 15
...Bellows type differential pressure sensor, 16...Curved lubricant disc type differential pressure sensor, 1B...Magnet, 2
2... Resonance circuit, 26... Oscillation circuit.

Claims (1)

[Claims] 1. A double container consisting of an inner cylinder containing a radioactive substance and an outer cylinder made of a non-magnetic material that surrounds and shields the inner cylinder, and which normally maintains the internal pressure of the outer cylinder at a predetermined level. At the same time, a differential pressure sensor is provided in the space between the outer cylinder and the inner cylinder, which has a detector that displaces due to pressure changes in the space, and a detection sensor that detects the displacement of the detector is installed in the space between the outer cylinder and the inner cylinder. A radioactive substance storage container is installed on the outer wall of the outer cylinder corresponding to the installation position of the pressure sensor, and is configured to detect gas leakage from changes in the internal pressure of the outer cylinder. 2. The radioactive substance storage container according to claim 1, wherein the differential pressure sensor is a mercury-filled U-tube differential pressure sensor with a magnet as a float. 3. Claim 1, characterized in that the differential pressure sensor is a gas-filled bellows or Lubutture disk type differential pressure sensor, and a magnet as a detector is attached to the movable end of the differential pressure sensor. Radioactive material storage container described in . 4 The differential pressure sensor described above is constituted by a resonant circuit whose resonant frequency changes according to the displacement of the detector in response to changes in the internal pressure of the outer cylinder, while the detection sensor has an oscillation circuit whose oscillation frequency is variable. A radioactive substance storage container according to claim 1, characterized in that: