JPS59126505A - Radiation damage recoverying method of image guide and image guide with heating means used for it - Google Patents

Abstract

PURPOSE:To recover light transmittivity easily and securely at low cost and to make a recovery from damage by heating an image guide when the image guide is damaged by radiation and decreases in light transmittivity. CONSTITUTION:A heater wire 2 is wound around an outer circumference of a bundle of many optical fibers 1 made of quartz glass to form a heating means, and a sheath 3 for the heat insulation and protection of the optical fibers 1 is provided around them. If the optical fiber 1 decreases in light transmittivity owing to radiation damage and provides a darker picture, the heater wire 2 is energized to heat the optical fiber 1, whose light transmittivity is recovered. This method is used preferably when optical fibers are used for monitoring, specially, nuclear power facilities, etc. Further, a heating device may be provided as a different body instead of winding the heating wire around the optical fibers directly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to radiation damage recovery of an image guide and an image guide with heating means used therein.

Image guides have also been developed as optical fibers, which have the function of receiving light from one end and transmitting it through the other end, and are used as various monitoring means and gamma signal means. There is.

The present invention also relates to an image guide for use in such a recovery method. This technique can be suitably used in cases where there is a possibility of exposure to radiation, such as in nuclear power facilities.

[Prior art]

Various image guides (including those called original fibers) are being developed, but these are because the light transmitting part is made of plastic, multi-component glass, quartz glass, etc. When exposed to measured doses of radiation, the light transmittance decreases due to radiation damage. Even with the highest standard image guide (optical fibre) currently being developed, if it is exposed to 106 integrated wires, the light transmittance decreases and the image becomes dark, causing problems. For example, in the vicinity of irradiated fuel in nuclear power facilities, the dose is more than 104 L/H, and the cumulative dose reaches about 106 within 100 hours, so this has become a concrete problem that poses practical problems.

However, in the past, no separate measures were taken to prevent damage to image guides caused by radiation, and therefore, if all image guides were used for monitoring or communication under high radiation conditions, the replacement interval would be shortened. Such inconveniences were inevitable.

The reason why no specific recovery technology for radiation damage has been developed in the past is that, first, it could not be used under such high doses, so there was no need or urgency to develop the technology. Second, it seems that there were difficulties in applying the technology to concrete measures, such as whether it would be possible to recover from the damage. In other words, it was easy to imagine that the recovery technique could be achieved by adopting a complicated or expensive device, but there was no need to go that far, and on the other hand, it was possible to achieve this goal with a simple configuration? This is because the current situation is that the technology to achieve this goal has not been thought of at all9.

[Purpose of the invention]

It is expected that there will be a need for monitoring and communication using image guys under high alk conditions in the future, but as mentioned above,
There are many problems with the current image guide (optical fiber),
Damage caused by radiation cannot be repaired and must be replaced.

The present invention was developed against the background of the above-mentioned circumstances, and its purpose is to restore the image guide optical fiber whose light transmittance has decreased due to radiation damage, and thereby to restore high radiation The object of the present invention is to provide a radiation damage recovery method for an image guide optical fiber (optical fiber) that can be used effectively even for monitoring and communication under low-intensity conditions, and an image guide (optical fiber) used therein. In addition, such recovery methods and image guides (optical fibers) can be achieved simply, easily, and inexpensively without using complicated configurations or expensive equipment, and can be easily applied to conventional methods. It is also aimed at

[Summary of the Invention In order to achieve the above object, the radiation a damage recovery method of the present invention is such that when the light transmittance of the image guide is reduced due to radiation, the light transmittance is reduced by completely heating the image guide. Take a recovery configuration.

In addition, the image guide developed by the present invention is provided with a heating means, and when the light transmittance has decreased due to radiation, the heating means restores the original transmittance to its full extent.

With such a configuration, it is possible to recover the decrease in transmittance due to radiation to 1η laughs, and this is extremely low.
Since this can be achieved with a clear configuration, it is very practical and advantageous even when used under high doses.

[Embodiments of the invention]

An embodiment of the present invention will be described below with full reference to FIG.

FIG. 1 is a structural diagram of an image guide with heating means according to this example.

This image guide is equipped with a heating means 2, and when the light transmittance decreases due to radiation, the light transmittance is restored by heating by the heating means 2.

By using all of the image guides equipped with heating means, it is possible to carry out a recovery method in which the light transmittance of the image guide is restored by heating the image guide.

To explain this embodiment in more detail, the following energization will be described. First, the image guide of this example is used as a heater wire heating means 2 in which a heater wire is completely wound around the outer periphery of an optical fiber 1 made of glass or the like. Furthermore, three outer sheaths are provided on top of this for heat insulation and protection of the optical fibers.

Now, if the light transmittance decreases due to radiation damage and the image becomes dark, it will be a problem. Judging the darkness here can be done visually depending on the situation of the image, or by monitoring the brightness of the monitor surface with a total illumination meter, etc., and checking that the brightness falls below a certain value. You can also judge. Other appropriate judgments can be made, but in any case, in the case of such a half-recovery of light transmission, the heating means 2 constituted by the heater is activated by energizing the heater, thereby increasing the temperature of the nine fibers 1. I will raise it to restore the light transmittance.

As described above, with this structure, it is possible to achieve reliable recovery of light transmittance very easily and quickly, and the structure is simple.

Note that the higher the temperature at which radiation damage is completely recovered, the faster the recovery is, and the higher the recovery rate of light transmittance is. In this example, the temperature was set at 100 C, which is practically heatingable and allows transmittance recovery in a heating time of 20 to 30 minutes.

If the temperature is set at 1ooc or higher, even if the image guide is made of quartz glass,
This short period of time, in which light transmission recovers in about 30 minutes, is sufficient for practical use.

FIGS. 3 and 4 show data regarding an image guide made of quartz glass. FIG. 3 shows the state of scraping due to radiation, and FIG. 4 shows the state of recovery due to heating.

FIG. 3 is a graph showing the change in light transmittance with respect to the irradiation amount when a quartz glass is irradiated with IR radiation.

From this figure, it can be seen that the transmittance drops to 20 inches or less of the pre-irradiation transmittance with an integrated dose of 2×107R (see data point P).

Figure 4 shows the quartz glass 'i20 with different r-ray irradiation levels for all units.
It is a graph showing the relationship between heating time and light transmittance when heated to 0t:'. The irradiation amount is O liter each.

The data shows the half-recovery of light transmission by heating at 200C for four types of lXl0'I(,,5X10'L 2X107).
I can see that he is recovering.

This data was taken at a set temperature of 200C.
Even at 00C, recovery can be achieved to a degree that poses no practical problem, although it takes a little longer.

Next, a modification of the above example will be explained with reference to Zheng 2' (i-diagnosis).

In this example, an image guide composed of an optical fiber 1 and an eyepiece 5 is used to move a high-dose monitored object 7 to a shielding wall 8.
It is configured as a monitoring device so that it can be constantly monitored outside the building. As mentioned above, the terms ``9゛γiva'' and ``image guide'' are not necessarily strictly defined;
Sometimes they are used synonymously, and sometimes they are referred to as a single optical fiber image guide, and an image guide configured using this is sometimes referred to as a fiber scope.

In this example, in such a monitoring device, an objective lens 4 placed under the high-ray tray and an optical fiber (1゛image guide) are used.
The heating device 6 is installed on the 114 products of the first product.

In contrast to the example shown in FIG. 1 in which the heater is directly wound around the optical fiber, in this example, a heating means is provided using six separate heating devices. Further, in the above example, a heating means of 7 Jl was provided over the entire length, but in this example, heating means is provided for local heating.

In this example as well, when the light transmittance decreases due to radiation damage and the lens becomes dark, the heating device 6
By heating the optical eyeper (image guide) 1, half of the light transmission can be restored.

The determination of the half-reduction in light transmission can be made in the same manner as explained in the example of FIG.

In this example, since the heating device 6 is provided only in the area under high radiation dose, the desired purpose can be achieved with a partial configuration. It may also be used in combination with a separate heating device as in this example.

In addition, in this book (d), it is determined by the setting value of the atmosphere gland where the image guide is placed, or by means of determining the atmosphere, and the heating temperature is determined according to the atmospheric dose.
By controlling the energization 'k'1lilJ to 6, etc.
The heating condition should be selected based on the atmosphere. As a result, t4 is set such that the rate of half-reduction in light transmittance due to heating is faster than the rate of half-reduction in light transmittance due to radiation of the image guide. As a result, the image guide can always maintain its good light transmittance.

[Effects of the invention] As mentioned above, the invention has made it possible to effectively use image guides (image guide fluorescent fibers for optical fiber monitoring and communication) whose light transmittance has decreased due to radiation damage. It can be done. In addition, the present invention can easily achieve all of the above even when applied to a conventional type, which is particularly advantageous to the housing.

It should be noted that, as a matter of course, the present invention is not limited to the illustrated examples.

1.2 Explanation of IIJJ of 1 RoJ FIG. 1 is a structural diagram showing one length of the image guide with heating means of the present invention. Figure 2 is a configuration diagram showing a different version of the present invention. FIGS. 3 and 4 are graphs for explaining the effects of one example.

1... Image guide (optical fiber), 2... Heater (heater), 6... Heating means (Karo heating device).

Agent: Patent Attorney Masami Akimoto No. 71”9 Cod 2 figure

Claims (1)

[Claims] 1. When performing monitoring or communication using an image guide, if the image guide loses its light transmittance due to radiation, the light transmittance can be restored by completely heating the image guide. This is a special feature of the image guide radiation damage recovery method. 2. The image guide is made of quartz glass, and its heating is 10 (I' or more), which shortens the recovery time for radiation damage. The radiation damage hole lJi method for an image guide according to claim 1. 3. The heating is performed by a heater wrapped around a part or the entire length of the image guide. The radiation damage recovery method for an image guide according to claim 1 or 2.4.Claims 1 to 3, characterized in that in the vicinity of a locally high radiation dose area, that area is particularly heated. The radiation damage recovery method for an image guide according to any one of paragraphs 5. All heating conditions are selected depending on the dose of the atmosphere in which the image guide is placed. A method of radiation damage to an image guide according to any one of claims 1 to 4 of the Zhao patent, characterized in that the recovery speed is fast and the light transmittance is maintained in a good state. Recovery method: 6. A heating means is provided in the image guide, and when the light transmittance of the image guide decreases due to radiation, the image guide is completely heated by this heating means to restore its light transmittance. 7. An image guide with a cam heating means, characterized in that: 7. Claim 6, characterized in that the heating means is constituted by a heater wrapped around a part or the entire length of the image guide. Image guide with heating means as described in Section 8. The heating state of the cam heating means shall be selected depending on the dose of the atmosphere in which the image guide is placed, and this will also reduce the rate of decrease in light transmittance of the image guide. The heating means according to claim 6 or 7, characterized in that the heating means is configured such that the speed of recovery of light transmittance is increased by the heat exchanger, and a good state of light transmittance can be maintained. Image guide included.