JPH02293647A - Spectral analysis apparatus of radioactive liquid - Google Patents

Abstract

PURPOSE:To recover a light transmitting fiber and a light receiving fiber from radiation damages and to spectrochemically analyze a radioactive liquid sample accurately over a long period of time in a high radiation field by periodically and alternately switching the fibers and passing stimulating light therein. CONSTITUTION:A valve 10 is opened and a liquid sample contg. a radioactive material is taken into an analyzing cell 9 from a process piping 12. The stimulating light from a laser 1 is then passed through the light transmitting fiber 7 and is projected to the sample. The fluorescence generated from the sample is passed through the light receiving fiber 8 and is transmitted to a spectroscope 2. Since the quantity of the fluorescence passing the fiber 8 during this time is slight, the fiber receives the radiation damages and is colored as time passes by. The fibers 7, 8 are, therefore, switched periodically by using a fiber switching mechanism 5 to use the light receiving fiber as the light transmitting fiber, by which the fibers are recovered from the radiation damages. The spectrochemical analysis of the sample is accurately executed over a long period of time in this way.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to remote spectroscopic analysis of liquids that contain a large amount of radioactive substances or are used in high radiation fields, and in particular, relates to the remote spectroscopic analysis of liquids that contain a large amount of radioactive substances or are used in high radiation fields. This article relates to a spectroscopic analysis device suitable for damage recovery and suppression.

[Conventional technology]

Conventionally, remote spectroscopic analyzers include, for example, Japanese Patent Application Laid-Open No. 58-1
As described in Japanese Patent No. 74832, a device using an optical fiber has been considered. However, if the sample or the environment emits radiation, there is a problem that the optical fiber becomes colored and the light transmission efficiency is greatly reduced.

[Problem to be solved by the invention]

Since the above-mentioned conventional technology does not take into account radiation damage to optical fibers, there is a problem in that in high radiation fields such as those in nuclear fuel reprocessing plants, the light transmission efficiency decreases significantly and measurement becomes difficult.

An object of the present invention is to provide a remote spectroscopic analysis device that can prevent a decrease in optical fiber transmission efficiency even in a high radiation environment such as a reprocessing plant.

[Means to solve the problem]

The above purpose is to make the arrangement of the sample cell and the two optical fibers optically equal, so that the transmission of excitation light to one optical fiber and the transmission of analysis light from the other optical fiber to the spectrometer are optically equal. This is achieved by driving the elements and switching them alternately. [Function] Of the two optical fibers, the excitation light transmitting fiber transmits high-intensity excitation light such as a laser, so that the colored center caused by radiation damage is removed and recovered by optical excitation, and new Prevents the occurrence of colored centers. During this time, the analytical light receiving fiber transmits only low-intensity analytical light, so radiation damage progresses. Therefore, by driving an optical element such as a reflector to send excitation light to the analytical light receiving fiber, this damage can be repaired and the sample liquid is irradiated with excitation light. Transmitted through optical fiber. This analysis light is guided to a spectrometer by driving an optical element.

By repeating this operation, radiation damage to the optical fiber can be appropriately recovered and measurement can be continued.

[Example〕 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of the device. A laser 1 as an excitation light source, a spectrometer 2, a photodetector 3, a data processing device 4, and
The fiber switching mechanism 5 is installed in an analysis chamber surrounded by a radiation-shielding wall 6. The light transmitting fiber 7 and the light receiving fiber 8 are connected to an analysis cell 9. The analysis cell 9 is connected to the process pipe 1 via the valve 1o and the sampling pipe 11.
2. The cross section of the analysis cell 9 is as shown in FIG. The light transmitting fiber 7 and the light receiving fiber 8 are connected to an analysis cell 9 by a fiber connector 13. A quartz cell 15 that takes in a liquid sample 14 is installed inside the analysis cell 9 and is connected to the sampling pipe 11.The analysis means first opens the valve 10 and collects the liquid sample containing radioactive substances from the process pipe 10. is taken into the quartz cell 15 in the analysis cell 9. Next, excitation light 16 from laser 1
is transmitted through the delivery fiber 7 and irradiates the liquid sample 14. Fluorescence 17 generated from liquid sample 14 is transmitted to spectrometer 2 through light receiving fiber 8, and a fluorescence spectrum is obtained using photodetector 3 and data processing device 4. If the output of the laser 1 is sufficiently large, the excitation level generated by the radiation in the light transmitting fiber 7 can be eliminated and coloring can be prevented, but since the amount of fluorescence passing through the light receiving fiber 8 is weak, as time passes, Color. Therefore, the roles of the light transmitting fiber 7 and the light receiving fiber 8 are periodically switched using the fiber switching mechanism 5. That is, the fiber used as the receiving fiber is used as the transmitting fiber to recover from damage to the broadcasting line. The fiber switching mechanism may mechanically switch the connectors. That is, as shown in FIG. 3, it consists of a rotary connector 18, a fixed connector 19, and an intermediate lens 20, and the role of the fiber is switched by the rotation of the rotary connector 18. In Fig. 2, the transmission fiber,
Since the positional relationship between the light-receiving fiber and connector and the quartz cell is optically the same, switching the fiber does not affect the analysis results.

As a fiber switching mechanism, a double-sided reflective mirror 21 or a single-sided reflective mirror 22 as shown in FIG. 4 may be used. In Figure 4,
The upper fiber is the light transmitting fiber 7 and the lower fiber is the light receiving fiber 8.Next, the double-sided reflector 21 is moved upwards and downwards in the paper, or the other-sided reflector 2 is moved in the plane of the paper.
When moving to position 2, the excitation light 16 enters the fiber 8, and the roles of the two fibers are reversed.

FIG. 5 is a modification of the analysis cell shown in FIG. 2. This is light gathering! 123 is used to bend the optical path of the excitation light 16 to irradiate the liquid sample, and the generated fluorescence 17 is also focused onto the light receiving fiber 8 by bending the optical path using the condensing mirror 23. A radiation shield 24 is arranged on the fiber end face. In the case of this analysis cell, radiation damage on the fiber end face can be reduced,
In addition, sensitivity can be improved by focusing fluorescence. Switching of the light receiving and light transmitting fibers is carried out in the same manner as in the analysis cell shown in FIG. 2.

As described above, according to this embodiment, it is possible to perform analysis while recovering radiation damage by transmitting laser light alternately to two fibers by rotating the connector of the light transmitting and receiving fibers, or by moving the reflecting mirror. suitable for in-line remote spectroscopy in high-radiation tubes such as reprocessing plants.

Another embodiment of the present invention will be described using FIGS. 6 and 7. FIGS. 6 and 7 are examples of using absorption analysis in conjunction with FIGS. 2 and 5, respectively.

In this case, there are two receiving fibers for fluorescence analysis, so the detection sensitivity of fluorescence analysis is also doubled. The light transmitted through the two receiving fibers is optically combined on the spectrometer side. Fiber switching is performed in the same manner as in the previous example. According to this embodiment, the advantage is that fluorescence and absorption analysis can be performed simultaneously with high sensitivity.

〔Effect of the invention〕

According to the present invention, by alternately switching the light transmitting fiber and the light receiving fiber to pass the excitation light, only one set of excitation light source and spectroscopy/detection system is required to photobleach the radiation damage of the fiber and remove the radioactive liquid sample. spectroscopic analysis can be performed with high accuracy over long periods of time in high radiation fields.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of an actual example of the present invention, Fig. 2 is a sectional view of an analysis cell, Figs. 3 and 4 are sectional views of two types of fiber switching mechanisms, and Figs. FIG. 7 is a sectional view of an analysis cell different from FIG. 2, respectively. 1... Laser, 2... Spectrometer, 3... Photodetector,
5... Fiber switching mechanism, 7... Light transmission fiber, 8
... Light receiving fiber, 9 ... Analysis cell, 14 ... Liquid sample, 18 ... Rotating connector, 21 ... Double-sided reflecting mirror, 22 ... Single-sided reflecting mirror, 23 ... Condensing mirror .

Claims (1)

[Claims] 1. An excitation light source, a spectrometer, a photodetector, a liquid sample cell, a light transmission fiber that transmits excitation light from the excitation light source to the sample, and transmitted light that has passed through the sample or from the sample. A liquid remote spectrometer comprising a sample cell and a light receiving fiber that transmits analytical light such as emitted fluorescence to the spectrometer, wherein the arrangement of the light transmitting fiber and the light receiving fiber is optically equal, and the excitation light source By driving an optical element to alternately switch the transmission of the excitation light from one optical fiber to the spectrometer and the transmission of analysis light from the other optical fiber to the spectrometer, A radioactive liquid spectrometer that uses excitation light to photobleach radiation damage alternately.