JPS5992375A - Radiation detecting method - Google Patents

Abstract

PURPOSE:To eliminate the need for a light transmitting means and to improve operatbility by using an optical fiber with a core part made of quartz glass containing an OH group as a radiation sensor, and receiving a radiation and causing fluorescence. CONSTITUTION:The sensor 1 made of the optical fiber consists of the core part 2 made of quartz glass containing an OH group and a clad part 3 made of silicone resin, and the OH-group content of the core part 1 is about 300-1,000. The radiation sensor 1 has such singular properties that it fluoresces intensely when receiving a radiation such as alpha-rays, electron rays, gamma-rays, X-rays, neutron rays, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation detection method that satisfies various points such as simplicity, economy, and reliability.

Discovery of radioactive contamination, detection of the presence or absence of radioactive materials, etc.
In the technical field related to measurement, there is a part that detects the properties of radiation or physical or chemical changes caused by the interaction between radiation and substances, and a processing part that processes information (for example, electrical signals) from the detection part. Generally, the detectors used to configure the above-mentioned detection section include an ionization chamber, Kishi ξ main body detector, proportional counter, Geiger Muller counter, scintillation detector, photographic emulsion, and thermoluminescent detector. Various sensing elements, BF3 counters, etc. are already available.

Since each of the above detectors has its own advantages and disadvantages, ξ
These are used depending on the detection situation, measurement conditions, etc. (〇) On the other hand, optical fibers are attracting attention as a radiation sensor different from the above ones, and in the case of this optical fiber, 7000 is inexpensive, It is said to offer various features such as easy installation in the detection area and high sensor functionality.

However, in the conventional radiation detection method using optical fibers, the presence or absence of radiation was detected by constantly passing optical signals through the optical fiber and deteriorating the transmission characteristics when the optical fiber received radiation. In view of the above-mentioned problems, the present invention is an improvement to the method of using an optical fiber as a radiation sensor, and the specific method is described below. The illustrated embodiment will be explained below.

FIG. 1 shows a radiation sensor 1 according to the present invention, and the sensor 1 made of an optical fiber is composed of a core part 2 made of quartz glass containing OH groups and a cladding part 3 made of silicone resin. The OH group content of the core portion 1 is about 300 to 1000.

The radiation sensor 1 described above has a unique property of strongly emitting fluorescence when exposed to radiation such as alpha rays, electron beams, gamma rays, X-rays, and neutron beams.

To explain this below, the core part 2 of the radiation sensor 1
contains <OH groups as described above, and when this radiation is irradiated, the holes and electrons in the core part 2 recombine without being captured by structural defects.

In other words, since the structural defect (Si-○) is combined with the OH group to form a partial structure (SiOH), the holes and electric peaks are not captured by this, and therefore, there are many O11 groups in the core part 21. , most of the hole-electron pairs generated by radiation irradiation will recombine, and these recombinations will generate fluorescence, and the amount of fluorescence generated will increase 01.
According to the results of experiments, when the cladding section 3 made of silicone resin was provided around the outer periphery of the core section 2, the amount of fluorescent light generated was greater.

Next, various optical fibers were irradiated with radiation of about 10'rad, and the resulting fluorescence is shown in the table below.

As is clear from the table above, the optical fiber used as the radiation sensor 1 preferably contains about 300 to 11,000 pp of OH groups in its core portion 2, and the cladding portion 3
It is best to use silicone resin.

In the present invention, radiation is detected using the radiation sensor 1 described above. In one embodiment of this, one end of the radiation sensor 1 is used as an incident end as shown in FIG. A photoelectric converter 4 and a meter 5 such as a voltmeter or an ammeter are sequentially connected.

The incident end of the radiation sensor 1 thus constructed is connected to the radioactive material 6.
When the substance 6 is directed toward the sensor 1, some radiation enters into the radiation sensor 1, and the core 2 of the material 6 generates fluorescent light, which is converted into an electrical signal via the photoelectric converter 4. After the conversion, the dose, dose rate, etc. from the meter 5 are converted into voltage or current values and read.

At this time, the radiation sensor 1 that has generated the fluorescent light is covered with a deep fluorescent color, and unless there is an opaque coating around the sensor's outer IC, the state of the fluorescent light generation can be visually confirmed. However, since it can be confirmed sufficiently, it is easy to check whether there is radiation or not just by visual inspection.

When detecting radiation using the method shown in FIG. 2, it is possible to measure the dose and dose rate of the radioactive substance 6, as well as inspect for radiation leakage and search for radioactive substances.

In the embodiment shown in FIG. 3, a radiation shielding system (safety device) is activated at the same time as radiation is detected. 9. A working chamber 10 is provided on the outside of the shielding chamber 9, and a shielding wall 11.12 is interposed at the boundary between these chambers 8.9.1o. A shielding shutter 13 is provided on the outside of the shielding chamber 12, and one end (incident end) of the radiation sensor 1 is inserted into the shielding chamber 9 from the working chamber 1o side. Attach the electric signal from the converter 4,
The signal is arranged so as to be input to the drive system 16 of the shielding shutter 13, which is equipped with a relay 14, a motor 15, and the like.

In FIG. 3 above (in this case, under normal conditions when there is no radiation leakage to the radiation source chamber 8 or shielding chamber 9, the shielding shutter 13 is not closed, but radiation leakage to the shielding chamber 9). When a field 8 occurs, the leaked radiation enters the radiation sensor 1, and the fluorescence generated in the core part 2 of the sensor 1 is converted into an electrical signal by the photoelectric converter 4, which is transmitted to the relay 14 of the drive system 16 (this The relay 14 then drives the motor 15 to close the shielding shutter 13 in the direction of the arrow in FIG.

Therefore, even if an emergency situation such as a radiation leak occurs,
At the same time, the shielding shutter 13 is closed, ensuring the safety of the work room 1o.In addition, at this time, the radiation sensor 1 becomes fluorescent due to the fluorescence generated through the leaked radiation. This makes it possible to detect radiation, and if necessary, the photoelectric converter 4 shown in FIG. 3 (the above-mentioned instrument 6 may be connected).

As explained above, the method of the present invention uses an optical fiber having a core made of quartz glass containing one O as a radiation sensor, and detects radiation by the generation of fluorescence of the sensor that receives radiation. Compared to the conventional method of detecting radiation based on changes in the transmission loss of the original fiber, this method eliminates the need for light passing means, resulting in significant cost reductions and simplified operability during detection. is not an iris like a crystal, but (
) Since quartz glass containing II groups can be used, the cost of the sensor itself can be reduced, and the range of applications is wide ranging, such as measurement of radiation dose and dose rate, exploration of radioactive substances, safety devices around radiation sources, etc. It also has versatility.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a radiation sensor used in the uninvented method.
FIGS. 2 and 3 are explanatory diagrams schematically showing an example of ray detection for each persimmon according to the method of the present invention. 1... Radiation sensor (optical fiber) 2...
Core part 3...Clad part 6...Radioactive material 7...Radiation source Patent applicant representative Patent attorney Makoto Ito

Claims (1)

[Claims] tl) A radiation detection method in which a source fiber having a core made of quartz glass containing an OH group is used as a radiation sensor, and radiation is detected by fluorescence generation of the sensor upon receiving radiation. (2) The radiation detection method according to claim 1, wherein the optical fiber has a cladding made of a silicone resin on the outer periphery of the core. (3) The content of OH groups in the core is from several hundred to several hundred. The radiation detection method according to claim 1 or 2, wherein the amount of radiation is 1,000 ppm.