JPS62191786A - Apparatus for detecting radiation leakage position - 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 <Industrial Application Field> The present invention relates to a radiation leakage position detection device that utilizes the characteristic that the optical transmission loss of an original phino-f increases when exposed to radiation.

Prior Art and Problems A wide variety of devices for detecting radiation have been known in the past. Conventionally, nuclear facilities and the like have used radiation detection devices to remotely detect the location of radiation leaks in the facilities. That is, a large number of radiation detection devices were installed at various locations in the facility, and the location of the radiation leak was determined from the devices that detected the radiation.

However, in such conventional methods, the position detection accuracy is proportional to the number of radiation detection devices installed, so in order to detect the radiation leak position with high accuracy, a large number of radiation detection devices must be prepared. Must be. For this reason, it costs a lot of money to detect the location of radiation leakage.
(1) There was a problem in that the operability of the device was extremely poor during the detection work.

Furthermore, in reality, in order to maximize the detection accuracy of the radiation leakage position, a countless number of detection devices are required, and the detection accuracy has often reached its limit.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a radiation leakage position detection device that is inexpensive, has good operability, and is capable of continuously detecting radiation leakage positions.

Means for Solving the Problems> The uninvented radiation leakage position detecting device includes optical fibers provided along five test specimens and a light source that enters light/virus into the optical fibers.

a detector for receiving backscattered light generated by scattering at each point in the longitudinal direction of the optical fiber from an input end of the optical fiber and detecting a change in the backscattered light; The present invention is characterized in that a radiation leakage position of the object to be inspected is detected.

Effect> When an optical fiber is irradiated with radiation, its optical transmission loss increases. For this reason, the backscattered light of the original pulse that has entered the optical fiber from the light source becomes difficult to transmit at the radiation irradiation position, and the change in the amount of backscattered light received by the detector from the input end of the optical fiber is affected by the radiation irradiation. The position decreases.

Therefore, the radiation irradiation position, that is, the radiation irradiation position of the object to be inspected can be detected by comparing this received light amount change characteristic with the backscatter source received light convergence change characteristic when the optical fiber is not irradiated with radiation.

Embodiment A radiation leakage position detection device according to an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the radiation leak position detection device consists of an optical fiber 4 installed along a test object 3 in which a gamma ray source 1 is surrounded by a heavy concrete wall 2, and a half-mirror attached to the optical fiber 4.
An Ar laser light source 6 inputs the original pulse through the optical fiber 4, and backscattered light of the original pulse generated by scattering at each point in the longitudinal direction of the optical fiber 4 is transmitted from the input end of the optical fiber 4 to a half mirror 5''f, The light receiver 7 receives light through the optical fiber 4, and the detector 7 together with the light receiver 7 constitutes a detector that detects changes in the backscattered light. The optical fiber 4 has a pure quartz core and a fluorine-doped quartz cladding Δn=1'%.

NA=0.2. Core diameter 5011m, fiber diameter 125μ
A 20 m step index type was used.

Radiation #i of the above configuration! According to the leakage position detection device, when the r-rays from the γ-ray source l are completely blocked by the heavy concrete wall 2, the characteristics of changes in the amount of backscattered light received from the optical fiber 4 are as shown in FIG. As shown in the figure, the optical fiber 4
It is displayed on the monitor 8 as a setan, which attenuates linearly from the input end to the output end. On the other hand, if there is a pinhole 2a in the heavy concrete wall 2, the optical fiber 4 is irradiated with rm leaked from the pinhole 2a. Since the optical transmission loss increases in the part of the optical fiber 4 that is irradiated with the r-rays, the characteristics of the amount of backscattered light received from the optical fiber 4 change as shown in FIG. The pattern is displayed on the monitor 8 as a pattern that decreases with a difference at the corresponding position. Therefore, by comparing all the patterns displayed on the monitor 8 in the case where there is no pinhole 2a and the case where there is a pinhole 2a, the optical fiber 4
The r-ray irradiation position, that is, the r-ray leakage position of the object to be inspected 3 can be detected. If the r-ray leakage part exists over the length range, as shown in Figure 4, the slope of the attenuation straight line will be displayed on the monitor 8 in accordance with the r-ray leakage range. A large portion appears.

Therefore, according to the radiation leakage position detection device described above, by simply providing the optical fiber 4 in the range where radiation leakage of the inspected object 3 is to be measured, radiation leakage can be detected continuously over the entire area along the optical fiber 4. The location of the leak can be detected by the monitor 8 at the remote location bi.

<Effects of the Invention> Since the radiation leakage position detection device of the present invention utilizes an optical fiber as a radiation detection sensor, the device can be simplified, operability improved, and inexpensive, and the radiation IR =
b=The leakage position can be continuously detected and the position detection accuracy can be dramatically improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a radiation leakage position detecting device according to a disaster example of the present invention, and FIGS. 2 to 4 are graphs of light reception slight change characteristics of Mugikata scattering 9, respectively. In the drawing, 3 is an object to be inspected, and 4 is an optical fiber. 6 is an Ar laser source; 7 is a light receiver; 8 is a monitor.

Claims (1)

[Claims] An optical fiber provided along an object to be inspected, a light source that inputs a light pulse into the optical fiber, and a backscattered light generated by scattering at each point in the longitudinal direction of the optical fiber is received from the input end of the optical fiber. What is claimed is: 1. A radiation leakage position detection device, comprising: a detector for detecting changes in the backscattered light; and detects a radiation leakage position of the object to be inspected based on change characteristics of the backscattered light.