JP3526999B2 - Radiation detector for high temperature incinerator monitor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation detector for a high temperature incinerator monitor for monitoring radioactive substances contained in exhaust gas of an incinerator for reducing the volume of waste in a nuclear power plant or the like.

[0002]

2. Description of the Related Art A high-temperature incinerator monitor is a method for measuring the concentration of radioactive substances contained in exhaust gas when incinerating in order to reduce the volume of waste such as used ion-exchange resin in nuclear facilities such as nuclear power plants. It is necessary for constant monitoring due to regulations. In order to measure the concentration of radioactive substances, the dust in the exhaust gas is collected by a filter, and the radiation (mainly gamma rays) emitted from the collected dust is detected by a radiation detector that is placed close to the filter. measure.

FIG. 11 is a conceptual diagram showing an example of a high temperature incinerator monitor according to the prior art. The exhaust gas from the incinerator is cooled by the cooling device 6 before entering the monitor in order to prevent the corrosive gas components and water contained therein from corroding the piping and the like. Then, water is removed and the sample gas is guided to the monitor at room temperature. The incinerator exhaust gas introduced through the incinerator exhaust gas introduction pipe 4 to the sample box 1 (in the claims, expressed as a dust trapping filter storage part, but hereinafter referred to as a sample box) is set in the filter holder 3. The dust contained therein is collected by the filter 2, and the radiation emitted from the dust is measured by the radiation detector 7 arranged immediately above the sample box 1. Filter 2
The exhaust gas that has passed through is sent out of the monitor through the exhaust gas exhaust pipe 5. The sample box 1 and the radiation detector 7 are
It is surrounded by a lead shield 80 to shield radiation from the outside and to make accurate measurements.

In this method, since hydrochloric acid and the like are generated by the cooling in the former stage, it is necessary to configure the cooling device 6 and the drain 61 with a corrosion-resistant material that is resistant to corrosion by the hydrochloric acid. Further, it has a drawback that accurate measurement cannot be performed because a part of dust is removed together with the corrosive gas and water, and that it requires a cooling device and is expensive. An example of this is JP-A-6-242291.

FIG. 12 is a conceptual diagram showing an example of a high temperature incinerator monitor according to the prior art which does not cool the exhaust gas. This is shown in Japanese Utility Model Laid-Open No. 61-193388. The exhaust from the incinerator is not cooled (approximately 200
C.), and the dust therein is collected by the filter as in FIG. 11 and measured by the radiation detector 7 arranged immediately above it. In FIG. 12, a portion corresponding to the sample box 1 of FIG. 11 is illustrated as a high temperature DUT 10. In this case, the radiation detector 7 is heated by the heat from the DUT 10 at a high temperature, and the radiation detector 7 cannot fully exhibit its function. Therefore, the radiation detector 7 is connected to the vacuum bottle 40 and two bottomed cylindrical gas flow members. Enclosed with 30 and air-cooled fan 20
The radiation detector 7 is cooled by the air cooling fan at the same time.
20 winds are passed between the two bottomed cylindrical gas flow members 30, and blown to the bottom of the vacuum bottle 40 from the flow holes 31 opened in the bottom of the outer bottomed cylindrical gas flow member 30 to blow the vacuum bottle 40. Is cooling. The vacuum bottle 40 and the bottomed tubular gas flow member 30 have a thickness of 1
Although it was made of a stainless plate of ˜2 mm, the temperature required for the radiation detector 7 was below 45 ° C. If the bottomed tubular gas flow member 30 is structured to allow cooling water to flow and the cooling water flows, the required temperature can be satisfied, but the structure becomes complicated and the cost increases.

FIG. 13 is a conceptual diagram showing another example of a high temperature incinerator monitor according to the prior art which does not cool the exhaust gas.
This is disclosed in JP-A-62-153788. Also in this case, the exhaust gas from the incinerator is introduced without being cooled, and the dust therein is collected by the filter as in FIG. 11 and measured by the radiation detector 7 arranged immediately above it. Also in FIG. 13, the portion corresponding to the sample box 1 of FIG. 11 is illustrated as the high temperature DUT 10. Also in this case, the radiation detector 7 is heated by the heat from the DUT 10 having a high temperature, and therefore the radiation detector 7 is provided with the two bottomed cylindrical heat insulating cylinders 60 and the bottomed cylindrical heat transfer cylinder 60 interposed therebetween. The heat radiation fin 74 provided at the end of the heat pipe 70 attached to the bottomed tubular heat transfer tube 50, which is surrounded by the heat tube 50, is cooled by the air cooling fan 20 to prevent heat from being transferred to the radiation detector 7. There is. By forming the bottomed tubular heat insulating tube 60 of fluororesin and the bottomed tubular heat transfer tube 50 of a material having a high thermal conductivity such as aluminum or copper, the temperature of the radiation detector 7 can be kept up to 60 ° C or lower. It has been realized to lower.

Since this structure requires a heat pipe, cooling fins, etc., it has a drawback that the structure is complicated, and the required temperature of the radiation detector 7 of 45 ° C. has not been reached.
Another conventional high-temperature incinerator monitor that does not cool the exhaust gas is a water-cooled system or a system that cools with cooled air, both of which are large-scale auxiliary equipment such as a water circulation device and a refrigerator. Is required, and it becomes economically expensive, including maintenance work for that.
Relocation is also difficult due to the need for piping and more equipment. Examples of these are JP-A-57-23874, JP-A-57-309698 and JP-A-63.
There is a publication of -302386.

[0008]

As described in the section of the prior art, cooling the exhaust gas from the incinerator has problems in terms of corrosion resistance and measurement accuracy. It is necessary to lead to the sample box without condensation. However, on the other hand, it is necessary to keep the temperature of the radiation detector at 45 ° C. or lower in order to fully exhibit the function of the radiation detector.

Therefore, the object of the present invention is to maintain the temperature of the radiation detector for measuring the radiation from the sample box introduced while maintaining the high temperature state where the exhaust gas from the incinerator does not condense at 45 ° C. or less. Another object of the present invention is to provide a simple radiation detection device for a high temperature incinerator monitor of a room temperature air cooling system.

[0010]

[Means for Solving the Problems] The means for suppressing the transfer of heat from the heat source to the object are (1) suppressing the heat dissipation from the heat source as much as possible, (2) the object (in this case, ,
Suppress the heat reception of the radiation detector) as much as possible,
And (3) to suppress heat transfer between them as much as possible,
(3) It is most important to suppress the heat transfer between the two as much as possible. Especially, the heat transfer by conduction and convection is almost completely cut off, and the heat transfer by radiation is suppressed. That is the point.

According to the present invention, (1) in order to suppress the heat dissipation from the heat source as much as possible, 1.1) by covering the high temperature part with a heat insulating material with a reflecting material except for the part which needs to be exposed. , The heat dissipation area is minimized. 1.2) At least the surface of the sample box 1 facing the radiation detector 7 is covered with an envelope made of a thin plate of a good electric conductor in a non-adhesive state to suppress radiation heat radiation.

This effect is further improved by making the surface of the thin plate made of a material having good electrical conductivity a polished surface or a smooth state, and is further enhanced by reducing the thickness to 15 to 70 μm. The reason why a thin plate made of a material with good electrical conductivity is used is that the thermal emissivity is proportional to the square root of the resistivity of the material, and it is greatly reduced when the thickness is thin. Further, the reason why the surface is made to be a polished surface or a smooth state is that the thermal emissivity is further reduced thereby. (Reference: Introduction to Heat Transfer, Written by Kudo, Yokendo, Material for Heat Transfer Engineering, Japan Society of Mechanical Engineers) For reference, the thermal emissivity ε on the polished surface at 200 ℃ is (heat transfer engineering (Source: Revised 4th Edition), Silver ε = 0.025 Copper ε = 0.03 Gold, Aluminum ε = 0.035 Iron ε = 0.07 Stainless steel ε = 0.13 For surface conditions (according to heat transfer overview), Polished surface of aluminum ε = 0.04 Aluminum Rough surface ε = 0.07 Polished surface of copper ε = 0.02 Matte surface of copper ε = 0.22 For the plate thickness (according to heat transfer general theory), in the case of iron, it is extremely thin ε ＝ 0.06 0.02mm ε ＝ 0.22 0.05mm ε ＝ 0.45 0.1 mm ε = 0.65 0.2 mm ε = 0.81 Extremely thick ε = 0.83 Note that according to the above-mentioned literature, the amount of heat transferred by radiation between the two parallel planes is proportional to the surface area thereof (T ₁ ⁴ −T ₂ ⁴ ) And 1 / [(1 / ε ₁ ) + (1 / ε ₂ ) -1] (Equation 1).

Here, the suffix 1 represents the high temperature side, the suffix 2 represents the low temperature side, T represents the absolute temperature, and ε represents the thermal emissivity. Since exhaust gas containing corrosive gas components and moisture passes through the inside of the sample box 1, the sample box 1 needs to be made of a corrosion resistant material. However, as can be seen from the above thermal emissivity data, corrosion resistant materials such as stainless steel have a considerably higher thermal emissivity than electrical conductors. (2) In order to suppress heat reception of the radiation detector as much as possible, the radiation detector is surrounded by an envelope made of a thin plate of a good electrical conductor to reduce the amount of radiant heat transmitted to the radiation detector.

In this case as well, it is effective to make the surface of the envelope a polished surface or a smooth state, like the envelope of the sample box. The reason why a thin plate with good electrical conductivity is used for the envelope of the radiation detector and the surface is polished or smooth is that as the thermal emissivity decreases, the amount of transferred radiant heat decreases. Is. (3) In order to suppress the heat transfer between the heat source and the radiation detector as much as possible, 3.1) The bottomed cylindrical heat shield member made of a thin plate with good electrical conductivity which surrounds the radiation detector in a non-contact state ( (Hereinafter, abbreviated as a heat shield member) is provided, and at least the outermost one of the heat shield members has a structure in which the bottom portion and the tubular portion are coupled in a thermally insulated state, or the bottom portion is The structure is doubled and the upper and lower bottom plates are connected in a thermally insulated state. 3.2) Between the radiation detector and the heat shield member, between the heat shield members when there are multiple heat shield members, and In the case of a double bottom, air is sent between the bottom plates to cool the radiation detector and the heat shield, and at the same time, transfer from outside the outermost heat shield to the outermost heat shield by conduction, convection and radiation. Near the inner wall of the outermost heat shield, heated by the generated heat The air layer is replaced so that heat is not transmitted to the inside by conduction and convection.

3.3) Further, the outermost heat shield member is covered with a heat insulating material with a reflecting material to suppress the introduction of heat from the cylinder,
The main heat introduction portion is limited to the bottom of the heat shield member.
The reason for forming the heat shield member with a thin plate of a good electrical conductor is
This is to reduce the transfer of heat by radiation, as can be seen from the above description of the thermal emissivity. Similarly, it is also effective to make the surface polished or smooth.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described in detail in the preceding paragraph, the basis of the present invention is to reduce the heat radiation area of the heat source as much as possible, and to reduce the heat transfer from the heat source to the radiation detector. Provide a heat shield member or envelope made of a small material, minimize the heat receiving area and heat radiating area of the heat shield member, and cut off heat transfer due to conduction and convection from a high temperature part and at the same time use a heat shield member. By providing an air blowing means for cooling, the amount of heat transferred to the radiation detector is made sufficiently small, and the radiation detector is air-cooled with air at room temperature to cool it to the required temperature range.

A detailed description will be given below with reference to embodiments.

[0018]

【Example】

(First Embodiment) FIG. 1 is a conceptual diagram of a first embodiment of the radiation detecting apparatus for high temperature incinerator monitor according to the present invention.
The same parts as those in the prior art use the same reference numerals, and the same applies to the following embodiments.

The incinerator exhaust gas is guided to the sample box 1 by the incinerator exhaust gas introduction pipe 4, passes through the filter 2 set in the filter holder 3, and is discharged from the exhaust gas exhaust pipe 5 to the outside. When passing through the filter 2, dust therein is collected by the filter, and radiation (γ rays) emitted from the dust is arranged outside the sample box 1 and directly above the filter 2. Measured by 7.

Since the exhaust gas contains corrosive gases such as hydrogen chloride, NO _x and SO _x, and water, the sample box 1
Is made of a metal material having excellent corrosion resistance such as corrosion resistant stainless steel or titanium. The incinerator exhaust introduction pipe 4, the sample box 1, and the exhaust discharge pipe 5 are at 185 to 200 ° C so that corrosive components and water in the exhaust do not condense.
Further, it is heated by the introduction pipe heater 41, the sample box heater 11 and the discharge pipe heater 51.

The radiation detector 7 is surrounded in a non-contact state by a heat shield member whose main material is aluminum having a polished surface of 1 mm in thickness. The tubular portion 91 and the bottom portion 92 of the heat shield member are made of aluminum, and the tubular portion 91 and the bottom portion 92 are joined in a heat insulating state. 2 and 3 show the combined state, FIG. 2 is a cross-sectional view of a main part, and FIG. 3 is a plan view seen from the bottom. The tube portion 91 and the bottom portion 92 of the heat shield member are provided at three locations near the outer periphery of the bottom portion 92 with screws 96 made of a heat insulating material via spacers 95 made of a heat insulating material between the tube portion 91 and the bottom portion 92. Combined by nuts 97. A portion without the spacer 95 is a void and is shown as a vent hole 94 in FIG. The air sent from the upper part of the radiation detector 7 through the duct 21 by the air-cooling fan 20 between the radiation detector 7 and the tubular portion 91 of the heat shield member passes through the ventilation hole 94 to the outside of the heat shield member. Sent to.

The air sent in this way cools the radiation detector 7 and the heat shield member 9 and at the same time, the radiation detector 7
It also replaces the air between the bottom of the heat shield and the bottom 92 of the heat shield. This displacement of air is heated mainly by the heat transferred from the sample box 1 to the bottom portion 92 of the heat shield member,
The heat of the upper surface of the bottom portion 92 of the heat shield member is rapidly eliminated, and heat is prevented from flowing into the radiation detector 7 by conduction and convection, and the heat transferred to the radiation detector 7 is mainly radiant heat. The state has been realized. The air sent from the vent 94 to the outside of the heat shield member is sent to the outside from the air outlet 22 opened in the upper part of the lead shield 80. This air flow acts as an air curtain, and the lower part It is prevented that the air heated in the high temperature part reaches the tube portion 91 of the heat shield member and transfers the heat to the heat shield member, and at the same time, the temperature of the air in the lead shield 80 is lowered.

In this embodiment, the direction of the air sent out from the ventilation hole 94 is shown to be a sideways direction, but the shape of the outer peripheral portion of the bottom part 92 is curved upward and sent in an obliquely upward direction. By doing so, the function of the air curtain becomes more effective. Since the tubular portion 91 and the bottom portion 92 of the heat shield member are coupled in a heat-insulated state, the only source of the radiant heat is the bottom portion 92 of the heat shield member, and the amount of radiant heat transmitted to the radiation detector 7 is reduced. It is greatly reduced. For reference, comparing the total surface area of the heat shield member with the surface area of only the bottom 92 is about 1/10 to 1/20.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
It is a conceptual diagram of the Example of. The difference between this embodiment and the first embodiment is that the bottom portion 92 of the heat shield member is a double bottom made of an aluminum plate having a polishing surface with a thickness of 1 mm. The central vent hole 941 is opened, and the upper bottom plate 921 and the lower bottom plate 922 are joined in a heat insulating state as in the first embodiment.

This double bottom structure has the effect of more reliably removing the air on the upper surface of the bottom portion 92 of the heat shield member, which is heated mainly by the heat transferred from the sample box 1 to the bottom portion 92 of the heat shield member. is there. In other words, the air sent between the radiation detector 7 and the tubular portion 91 of the heat shield member is transferred to the bottom plate 92 on the upper side.
1 center vent 941 to upper bottom plate 921 and lower bottom plate 92
It is sent between 2 and through it, and is sent out from the side vent 942. Therefore, since the air is surely sent between the upper bottom plate 921 and the lower bottom plate 922, the removal of the heated air becomes much more reliable.

Further, since the heat transmitted by conduction and convection from the sample box 1 is not transmitted to the upper bottom plate 921 which directly faces the radiation detector 7, the upper bottom plate 921 is lower than the lower bottom plate 922. It also works to shield radiant heat. (Third Embodiment) FIG. 5 is a conceptual diagram of a third embodiment of the present invention.

In this embodiment, the outer side of the tubular portion 91 of the heat shield member in the first embodiment is covered with a heat insulating material 15 with a reflecting material, the radiant heat is blocked by the reflecting material 14, and the heat insulating material 13 is used. The heat due to conduction and convection is blocked, and the heat reception of the tubular portion 91 of the heat shield member is suppressed. (Fourth Embodiment) FIG. 6 is a conceptual diagram of a fourth embodiment of the present invention.

In this embodiment, at least the radiation detector 7 at the center of the bottom portion 92 of the heat shield member in the third embodiment is used.
The part opposite to is a 75 μm thick aluminum plate (the bottom ultrathin plate 99 in the figure). The bottom ultrathin plate holding member 98 holds the bottom ultrathin plate 99, and the holding part 98 and the tubular portion 91 of the heat shield member sandwich a spacer 95 made of a heat insulating material with a screw 96 and a nut made of a heat insulating material. It is fixed at 97, and the tubular portion 91 is covered with a heat insulating material 15 with a reflecting material.

If the plate thickness of the bottom portion 92 is made extremely thin, its thermal emissivity becomes small as described in the section (Means for solving the problem), so that the radiation is transmitted from the bottom portion 92 to the radiation detector 7. The radiant heat generated is reduced. Furthermore, thinner, 20 μm thick
When a plate of a certain degree is adopted, instead of holding only the outer peripheral portion as in this embodiment, it is held by a grid-like holding member, or between two thin plates, heat such as fluororesin is used. As a laminated plate having a structure in which plates having a large porosity (for example, punching sheets) made of an insulating material are sandwiched,
It may be held by a holding member as in this embodiment.

Although the embodiment shows the case of a single bottom, naturally, it is also effective in the case of a double bottom. In that case, it is more effective to apply to the lower bottom having the highest temperature. (Fifth Embodiment) FIG. 7 is a conceptual diagram of a fifth embodiment of the present invention. This embodiment is the same as the first embodiment except that the high temperature portion serving as the heat source is covered with the heat insulating material 15 with a reflector except for the portion that cannot be covered. The part that cannot be covered is the part of the sample box 1 facing the radiation detector 7, and if this part is covered with a heat insulating material, the distance between the sample box 1 and the radiation detector 7 will be too large and the required radiation sensitivity will be obtained. It cannot be covered because it cannot be secured.

By covering the high temperature part which can be a heat source, the heat radiation amount into the lead shield 80 can be greatly reduced, the temperature rise of the air in the lead shield 80 can be reduced, and the radiation can be transmitted through the heat shield member. The amount of heat introduced into the detector 7 is greatly reduced. Therefore, the capacity of the air cooling fan 20 can be small. Of course, the same effect can be obtained by combining with an embodiment other than the first embodiment.

(Sixth Embodiment) FIG. 8 shows a sixth embodiment of the present invention.
It is a conceptual diagram of the Example of. In this embodiment, the stainless steel outer case of the radiation detector 7 in the first embodiment is replaced by a radiation detector envelope 72 made of gold having a thickness of 1 mm and having a polished surface. is there. This effect can be estimated by changing ε ₂ from the value of stainless steel to the value of gold having a polished surface in (Equation 1) in the section (Means for Solving Problems), and With aluminum having a 1 mm thick polished surface, it is about half that of stainless steel.

In this embodiment, the case where the outer case of the radiation detector 7 is replaced by the radiation detector envelope 72 has been described, but the radiation detector envelope 72 may be provided outside the radiation detector 7 in the same manner. Is effective for. (Seventh Embodiment) FIG. 9 is a conceptual diagram of a seventh embodiment of the present invention.

This embodiment is the same as the first embodiment except that at least a portion of the sample box 1 facing the radiation detector 7 has a 0.1 mm-thick polished surface made of aluminum and has a sample box envelope. 12 is arranged in a non-contact state. The effect of this envelope 12 is that the radiation of radiant heat from the stainless steel sample box 1 which requires corrosion resistance is changed to the radiation of aluminum having a polishing surface with a thickness of 0.1 mm. If is aluminum having a polished surface with a thickness of 1 mm, it will be about 1/2 according to (Equation 1) in the section (Means for Solving the Problem).

(Eighth Embodiment) FIG. 10 is a conceptual diagram of an eighth embodiment of the present invention. In this embodiment, the aluminum heat shield member having a polishing surface is tripled in the fifth embodiment, and the radiation detector 7 has a thickness 1 having a polishing surface.
An enclosure 72 for a radiation detector, in which copper of mm is plated with gold, is provided. In the inner double layer of the triple heat shield member, the cylindrical portion and the bottom portion are not thermally insulated.

The cooling air from the air-cooling fan 20 is sent between the radiation detector 7 and the inner heat shield 9a through the duct 21, and the ventilation hole 94 opened at the lower part of the heat shield 9a. Through, between the inner heat shield 9a and the middle heat shield 9c, sent upward, through the vent hole 94 opened at the top of the heat shield 9c, the middle heat shield 9c and the outer heat shield 9c. Go out between the heat shield 9b,
The air is sent downward again, passes through the air holes 94 formed in the lower portion of the outer heat shield 9b, exits into the space inside the lead shield 80, and is sent out from the air outlet 22 opened in the lead shield 80. The air outlet 22 is formed in a dogleg shape or the like, if necessary, in order not to impair the shield effect of the lead shield 80.

In the structure of this embodiment, the radiation detector 7 is made of aluminum having a polishing surface of 1 mm in thickness as the heat shield member.
3mm spacing on the side of, and 1mm spacing on the bottom,
When the wind speed between the radiation detector 7 and the heat shield member 9a on the inner side was set to 30 m / sec, the temperature rise of the radiation detector 7 was obtained as the temperature of the air discharged from the air cooling fan + 2 ° C. . The result is that when combined with the temperature increase of air in the air cooling fan of 5 ° C, the temperature rises by 7 ° C from the temperature of room temperature air, and the maximum ambient temperature is 35 ° C.
In this case, the target of the temperature of the radiation detector 7 being 45 ° C. or lower is sufficiently satisfied.

Since it is considered that the wind speed and the temperature rise of the radiation detector 7 are in inverse proportion to each other, even when the wind speed is 10 m / sec, if the triple heat shield member is used, the temperature is 11 ° C. higher than the temperature of room temperature air. The temperature rises and the target can be almost satisfied. In FIG. 10, the vent hole 94 opened in the heat shield member 9a on the inner side is only the cylindrical portion, but it is effective to open it in the bottom portion as well to improve the air replacement between the bottom plates.

In the above-described embodiments, increasing the number of heat shield members within a range in which the sample box 1 and the radiation detector 7 can be accommodated within the allowable maximum distance reduces the radiation heat received by the radiation detector 7. It is effective to do. However, since the additional effect is relatively small, it can be said that the most efficient number of heat shield members is about three. The triple heat shield member in the eighth embodiment, the heat insulating material 15 with a reflector for the high temperature portion, and the sample box enclosure 12
The temperature of the radiation detector 7 in the natural cooling state, in which the air blow by the air-cooling fan 20 is stopped while the enclosure for radiation detector 72 in which 1 mm thick copper is plated with gold is also used, is 60 ° C.
Met. This is because even if the amount of heat supplied as radiant heat by the envelope or heat shield member is sufficiently suppressed, the amount of heat supplied by conduction or convection is greatly increased by stopping the air flow. Since the cooling effect of the detector 7 becomes very poor, it is considered that the temperature was raised to 40 ° C. higher than room temperature.

In the above embodiments, the material of the envelope and the heat shield member has been described as aluminum or copper with gold plating. However, the material is not limited to this and may be a good electrical conductor according to environmental conditions and cost conditions. It can be used by selecting it from among. Regarding the thickness, the thinner it is, the more effective it is. However, similarly, it is effective to determine the thickness from practical conditions.

As for the surface condition, it is desirable to make it a polished surface as long as it satisfies practical constraints. In the case where there is one heat shield member, the vent hole 94 is not opened at the bottom in order to prevent the sample box 1 from being cooled by the air sent out from this hole and to prevent dew condensation inside the sample box 1. is there.

[0042]

According to the present invention, in order to suppress the heat dissipation from the heat source as much as possible, the heat dissipation is achieved by covering the high temperature part with the heat insulating material with the reflecting material except the part that needs to be exposed. Sample box 1 with the smallest area
At least the surface facing the radiation detector 7 is covered with an envelope made of a thin plate of a good electric conductor in a non-adhesive state,
It suppresses the dissipation of radiant heat.

Next, in order to suppress heat reception of the radiation detector as much as possible, the radiation detector is surrounded by an envelope made of a thin plate of a good electric conductor to reduce the absorbed radiant heat quantity. However, the most important point of the present invention is to suppress heat transfer between the heat source and the radiation detector as much as possible.
A heat shield member made of a good electrical conductor thin plate that surrounds the radiation detector in a non-contact state is provided, and among the heat shield members,
At least the outermost one has a structure in which the bottom part and the cylinder part are connected in a heat-insulated state, or a structure in which the bottom part is doubled and the upper and lower bottom plates are connected in a heat-insulated state. , Air is sent between the radiation detector and the heat shield member, between the heat shield members when there are multiple heat shield members, and between the bottom plate when there is a double bottom, so that the radiation detector and the heat shield member are connected. At the same time as cooling, it replaces the air layer near the inner wall of the outermost heat shield member, which is heated by the heat transferred from outside the outermost heat shield member to the outermost heat shield member by conduction, convection and radiation. Furthermore, it is to prevent heat from being transferred to the inside by conduction and convection.

In order to suppress heat transfer between the heat source and the radiation detector as much as possible, the outermost heat shield member is covered with a heat insulating material having a reflecting material to suppress the introduction of heat from the cylinder. is doing. The reason for forming the envelope and the heat shield member with a thin plate of a good electrical conductor is to reduce the introduction of heat due to radiation, as can be seen from the above description of the thermal emissivity, and the surface is a polished surface or a smooth surface. The reason for setting the status is the same.

As described in the description of the eighth embodiment,
By combining the triple heat shield member, the air blower, the envelope, and the heat-insulating material coating of the heat source part, it is possible to achieve the temperature of the radiation detector 7 to be 45 ° C or lower at the maximum ambient temperature of 35 ° C. The object of the invention could be achieved. The envelope 12 of the sample box 1 has a simple structure, and the envelope 72 of the radiation detector 7 is made by changing the container made of stainless steel in the prior art to a container made of a material having good electrical conductivity. Can handle. The outer heat shield member is fixed with a screw nut made of a heat insulating material with a spacer made of a heat insulating material sandwiched in order to make the cylindrical portion and the bottom portion in a heat insulating state.
It is not so complicated in structure. By sending cooling air between the heat shield member and the radiation detector 7 or between the heat shield members, the radiation detector 7 is efficiently cooled, and at the same time, the heat shield member itself is efficiently cooled. Therefore, the object of the present invention can be achieved.

Since the envelope 72 of the radiation detector 7 is made of a material having good electrical conductivity, another effect of preventing electromagnetic noise from mixing in the photomultiplier tube and electronic circuit inside the detector is also realized. it can.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a first embodiment of a radiation detecting apparatus for a high temperature incinerator monitor according to the present invention.

FIG. 2 is a sectional view of a main part of the first embodiment.

FIG. 3 is a plan view of the first embodiment viewed from the bottom.

FIG. 4 is a conceptual diagram of a second embodiment according to the present invention.

FIG. 5 is a conceptual diagram of a third embodiment according to the present invention.

FIG. 6 is a conceptual diagram of a fourth embodiment according to the present invention.

FIG. 7 is a conceptual diagram of a fifth embodiment according to the present invention.

FIG. 8 is a conceptual diagram of a sixth embodiment according to the present invention.

FIG. 9 is a conceptual diagram of a seventh embodiment according to the present invention.

FIG. 10 is a conceptual diagram of an eighth embodiment according to the present invention.

FIG. 11 is a conceptual diagram showing an example of a radiation detecting device for a high temperature incinerator monitor according to the prior art.

FIG. 12 is a conceptual diagram showing another example of the radiation detecting device for the high temperature incinerator monitor according to the prior art.

FIG. 13 is a conceptual diagram showing still another example of the radiation detecting apparatus for the high temperature incinerator monitor according to the prior art.

[Explanation of symbols]

1 sample box 11 Sample box heater 12 Sample box enclosure 2 filters 3 filter holder 4 Incinerator exhaust introduction pipe 41 Heater for incinerator exhaust gas introduction pipe 5 Exhaust pipe 51 Exhaust pipe heater 6 Cooling device 61 Drain 7 Radiation detector 71 Radiation detector signal / power cable 72 Radiation detector enclosure 73 Radiation detector body 9 Heat shield member 9a Inner heat shield 9b Outside heat shield 9c Intermediate heat shield 91 Heat shield member tube 92 Bottom of heat shield 921 Upper bottom plate 922 Bottom plate 93 Lid of heat shield 94 air vent 941 central air vent 942 Side vent 95 Spacer made of heat insulating material 96 Screw made of heat insulating material 97 Nuts made of heat insulating material 98 Holding member for the bottom ultra-thin plate 99 bottom ultra-thin plate 10 High temperature DUT 15 Reflective material with thermal insulation 13 Thermal insulation 14 Reflective material 20 Air cooling fan 21 Duct 22 Air outlet 30 Bottomed cylindrical gas flow member 31 Flow hole 40 vacuum bottles 50 Bottomed cylindrical heat insulation cylinder 60 Bottomed cylindrical heat transfer tube 70 Heat pipe 74 Radiating fin 80 lead shield

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Claims (10)

(57) [Claims] 1. Dust contained in exhaust gas from an incinerator,
High temperature used for high-temperature incinerator monitors that collect radioactive dust in exhaust gas by collecting it with a filter inside the dust collection filter and measuring the radiation emitted from the collected dust with a radiation detector. In a radiation detection device for an incinerator monitor, a bottomed cylindrical heat shielding member that surrounds the radiation detector in a non-contact state and is made of a thin plate of a good electrical conductor, and is at least the outermost bottomed cylindrical heat shielding member. There is no heat between the tube and the bottom.
Coupled via the strip, between the solid body between the thermal conduction on the heat-insulating structure has been that the bottomed cylindrical heat shielding member, the radiation detector and the bottomed cylindrical heat shield member, and a bottomed cylinder A radiation detecting device for a high temperature incinerator monitor, comprising: a blower for sending air between the bottomed cylindrical heat shields when there are a plurality of heat shields. 2. The dust contained in the exhaust gas from the incinerator,
High temperature used for high-temperature incinerator monitors that collect radioactive dust in exhaust gas by collecting it with a filter inside the dust collection filter and measuring the radiation emitted from the collected dust with a radiation detector. In a radiation detection device for an incinerator monitor, a bottomed cylindrical heat shield member made of a thin plate of a good electrical conductor that surrounds the radiation detector in a non-contact state, and at least the outermost bottomed cylindrical heat shield member is It has a double bottom and its upper and lower bottom plates are connected via a heat insulating material.
It is, are the insulating structure in the solid body between the conductive heat transfer on the heat, and the bottomed cylindrical heat shield member which hole is opened in the vicinity of at least the central portion of the upper bottom plate, the radiation detector and the bottomed cylindrical heat Blower means for sending air between the shield members, between the upper bottom plate and the lower bottom plate of the double bottom, and between the bottomed tubular heat shield members when there are a plurality of bottomed tubular heat shield members. And a radiation detecting device for a high temperature incinerator monitor, which comprises: 3. The radiation detector for a high temperature incinerator monitor according to claim 1 or 2, wherein the surface of the electrically conductive thin plate is a polished surface or a smooth state. Detection device. 4. The radiation detecting apparatus for a high temperature incinerator monitor according to claim 1, wherein the bottom of the bottomed cylindrical heat shield member is at least the bottom of the radiation detector. A radiation detecting device for a high temperature incinerator monitor, characterized in that the thickness of a thin plate of a good electric conductor corresponding to the area of 15 to 100 μm. 5. The radiation detecting apparatus for a high temperature incinerator monitor according to claim 1, further comprising a reflecting material that covers an outer side of a tubular portion of the outermost bottomed tubular heat shield member. A radiation detector for a high temperature incinerator monitor, which is provided with a heat insulating material. 6. The radiation detecting apparatus for a high temperature incinerator monitor according to claim 1, wherein a portion of the surface of the filter housing portion that does not face the radiation detector and an exhaust gas. A radiation detecting apparatus for a high temperature incinerator monitor, characterized by comprising a heat insulating material having a reflecting material on a surface thereof, which covers the introduction pipe and the discharge pipe of the above. 7. The radiation detecting apparatus for a high temperature incinerator monitor according to any one of claims 1 to 6, further comprising: an enclosure made of an electrically conductive thin plate that surrounds the radiation detector. Characteristic radiation detector for high temperature incinerator monitor. 8. The radiation detector for a high temperature incinerator monitor according to claim 7, wherein the surface of the envelope of the radiation detector is a polished surface or a smooth state. Detection device. 9. The radiation detecting device for a high temperature incinerator monitor according to claim 1, wherein at least a surface of the filter accommodating portion facing the radiation detector is a thin plate made of a good electrical conductor. A radiation detecting device for a high temperature incinerator monitor, characterized in that it is covered with a non-adhesive state. 10. The radiation detecting apparatus for a high temperature incinerator monitor according to claim 1, wherein the air blowing unit is one air cooling fan, and the air is first blown. A downward flow is made between the radiation detector and its closest bottomed cylindrical heat shielding member, and the air is sent out from a ventilation hole opened at the bottom of the bottomed cylindrical heat shielding member to form a bottomed cylindrical heat shielding member. If there are a plurality of holes, the hole between the closest closed bottom cylindrical heat shield member and the second adjacent bottomed cylindrical heat shield member is sent upward to open above the second adjacent bottomed cylindrical heat shield member. A radiation detecting device for a high-temperature incinerator monitor, which is characterized in that the air is sent by a method of sending it out further and sending the next interval downward.