JPH0567888B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a flame detection device for a radioactive waste incineration facility.

(Prior Art) A hot air generating furnace for preheating and auxiliary combustion of a radioactive waste incinerator is provided with a flame detection device for checking the presence or absence of ignition. This type of flame detection device is designed to operate in response to ultraviolet rays, but the problem is that it also responds to X-rays, gamma rays, etc., causing malfunctions and making it impossible to accurately detect ignition. It was hot.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems and provides a radioactive waste disposal method that can accurately detect flames without causing malfunctions due to X-rays, γ-rays, etc. It was completed for the purpose of being a flame detection device for material incineration equipment.

(Means for Solving the Problems) The present invention includes installing a detector that detects flame in response to ultraviolet rays at a position where the inside of the furnace can be seen only through a reflector provided midway;
This detector is characterized in that its outer periphery including the front surface is surrounded by a lead shielding plate.

(Embodiments) Next, the present invention will be explained in detail with reference to the illustrated embodiments. 1 is a detector sensitive to ultraviolet rays, and 2 is a furnace such as a hot air generator for auxiliary combustion in a radioactive waste incinerator. . The detector 1 is installed outside the furnace wall 4, and the detector 1 and the furnace 2 are connected to the furnace wall 4.
However, the detector 1 can only see the inside of the furnace 2 through reflectors 5, 5 installed in the middle, and cannot directly see the inside of the furnace 2. It is installed in a position where it cannot be accessed.
As the reflector 5, a material having excellent reflectivity for ultraviolet rays is used, such as a silicon crystal plated with gold or a silicon crystal coated with aluminum and magnesium fluoride. Further, the detector 1 is entirely covered with a shielding plate 6 made of lead.
The shielding plate 6 is composed of a circular plate 6a that covers the front and rear surfaces of the detector 1, and a ring 6b that covers the outer periphery. It is supported by a receiving rod 8. Here, the required thickness of the shielding plate 6 is 0.5 mR/h, which changes the target dose value from the current 5 mR/h to 0.5 mR/h.
If the calculation is performed assuming that all γ-ray sources are ⁶⁰ Co in accordance with the design of the existing miscellaneous solids incineration facility, the attenuation will be 44 mm. In this case, if the dimensions necessary to cover the detector 1 are, for example, 240 mm in diameter and 280 mm in length, the weight of the entire shielding plate 6 will reach over 100 kg, making it difficult to handle. Therefore, in the embodiment, the whole ring 6b is divided as shown in the figure, and the weight of one ring 6b is approximately
It was designed to stay at around 30kg. Therefore, the embodiment can be easily assembled by attaching the rings 6b one by one to the receiving rod 8, and can be easily disassembled by reversing the procedure when inspecting the detector 1. It is possible.

Note that when the rings 6b are brought into close contact with each other as shown in the figure, there is a risk that the temperature of the internal space will rise, and to avoid this, it is necessary to form a gap between the rings 6b to allow ventilation. desired.
However, in that case, radiation may enter the interior through the gap and cause malfunction, so a step 9 is formed on each ring 6b as shown in FIG. 2 to prevent radiation from entering and to allow ventilation. It is preferable to secure it.

(Function) In the device configured as described above, the detector 1 receives ultraviolet rays generated from the flame inside the furnace 2 to confirm ignition and extinguishment. Although ultraviolet rays can be reliably detected because the mirror is installed in a position where the inside of the furnace 2 can be seen, high-energy electromagnetic waves such as X-rays and gamma rays pass straight through the reflector 5. It does not enter the detector 1 because it is stored away. Therefore, according to the present invention, the possibility that X-rays or γ-rays enter through the light entrance window of the detector 1 and cause malfunctions can be prevented. Moreover, since the outer periphery of the detector 1 including the front surface is covered with a shielding plate 6 made of lead material with high radioactivity blocking properties, radiation generated from a radioactive waste incinerator, etc. can fly to the detector 1 from the surrounding area. It is also reliably prevented from causing malfunctions. Therefore, if the flame detection device of the present invention is used, the X
The presence or absence of flame can be accurately detected without causing malfunctions due to radiation, gamma rays, etc. Furthermore, if the shielding plate 6 is of a split type as in the embodiment, the weight per sheet can be reduced and handling can be facilitated.

(Effects of the Invention) As is clear from the above description, the present invention can accurately inspect flames without causing malfunctions due to X-rays, γ-rays, etc. generated from radioactive waste incinerators, etc. Therefore, it will greatly contribute to the development of industry as a flame detection device for radioactive waste incineration facilities that eliminates the problems of conventional methods.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view showing an embodiment of the present invention, and FIG. 2 is a side view showing main parts of another embodiment. 1...Detector, 2...Furnace, 5...Reflector, 6...
…Shield.

Claims (1)

[Claims] 1. A detector 1 that detects flames in response to ultraviolet rays is installed in a position where the inside of the furnace 2 can be seen only through a reflector 5 provided midway, and
The outer periphery of this detector 1 including the front surface is covered with a lead shielding plate 6.
A flame detection device for a radioactive waste incineration facility, characterized in that it is surrounded by.