JP3716285B2 - Ceramic radon emission source and method for manufacturing the same - Google Patents

Description

[0001]
The present invention relates to a radon emission radiation source that emits radioactive radon for the purpose of studying radiation exposure, and the like, and by fixing a radium salt insoluble in water to a ceramic carrier made of porous ceramics, the radioactive radon gas has a high emission rate The present invention relates to a ceramic radon emission radiation source capable of stably taking out a product over a long period of time.
[0002]
[Prior art]
Although radon is a kind of rare gas element, a uranium nuclide having a mass number of 222, an actinium nuclide having a mass number of 219, and a thorium nuclide having a mass number of 220 are naturally present. The mass 222 radon is produced by the decay of mass 226 radium.
Up to now, research on radon concentration measurement in living environment from the viewpoint of biological, medical or radiation exposure protection, or the effects of this radon exposure on the living body have been studied. Radon emission source is a good source.
[0003]
Conventionally, radium aqueous solutions, radon-releasing soil collected from nature, commercially available solid radon sources, and the like have been used as radon sources in experiments on the effects of radon exposure on living bodies. However, all have the disadvantages that radon release rate is low, handling is difficult, and radon is not released stably.
[0004]
[Problems to be solved by the invention]
For example, in the study of exposure effects on living bodies due to radon, the characteristics required as radon sources used in animal experiments etc. are as follows. First, high-rate release that releases high concentrations of radon gas to the extent that exposure effects can occur on the living body. Secondly, in a long-term experiment or the like, there is a need for durability that stably releases a high concentration of radon gas, and thirdly, stability such as easy handling and high water resistance. However, none of the conventional radon sauces have such characteristics.
[0005]
Therefore, in view of the problems in the conventional radon source and the characteristics required for the radon source, the present invention can stably release a high concentration of radon gas over a long period of time, and is easy to handle, water resistant and water resistant. We propose a ceramics radon emission source with high radiation and its manufacturing method.
[0006]
[Means for Solving the Problems]
  In order to achieve the above object, in the present invention, a porous ceramic is used as a carrier, and a radium salt insoluble in water is fixed on the ceramic carrier.
  That is, the ceramic radon emission radiation source according to the present invention has a radioactive radium insoluble in water fixed on a ceramic carrier made of porous ceramics.This ceramic carrier is made of SiC porous sintered body or TiO ₂ Is a porous sintered body of SiC coated withIt is characterized by that.
[0007]
Such a ceramic radon emission source includes a first step of obtaining a ceramic carrier made of porous ceramics, a second step of impregnating the ceramic carrier with a radioactive radium solution, and a radioactive insoluble in water in the ceramic carrier. It can be manufactured through a third step of precipitating a salt of radium and a fourth step of sintering this radium salt and fixing it to a ceramic carrier.
[0008]
  For example,A ceramic carrier made of a porous sintered body of SiC is impregnated with a radium solution and then dried.₂SO₄Impregnated with RaSO insoluble in water inside the ceramic carrier₄ Precipitates. Thereafter, the ceramic carrier is heat-treated at a high temperature to thereby obtain the insoluble RaSO.₄ Sinters and settles on the ceramic carrier.
[0009]
TiO₂After impregnating a ceramic carrier made of a porous sintered body of SiC coated with a radium solution and drying, the ceramic carrier is then impregnated with ammonium acetate or the like, whereby radium acetate is precipitated inside the ceramic carrier. Thereafter, this ceramic carrier is heat-treated at a high temperature to thereby render RaTiO insoluble in water._ThreeAre formed and sintered and fixed inside the ceramic carrier.
[0010]
Such a ceramic radon emission source is a porous sintered body, in which radioactive radium insoluble in water is fixed inside a porous ceramic that is resistant to radiation and chemically stable. Very stable radon release characteristics. Moreover, since radium is sintered in the form of a salt insoluble in water and fixed on the porous ceramic carrier, the radium itself is physically and chemically stable, and the radium can be easily removed from the ceramic carrier by water or the like. Does not elute. Further, as will be described later, radon can be stably and continuously released at a high concentration over a long period of time. Moreover, since it is a solid, its handling is easy.
[0011]
The sintering temperature of the radium salt is preferably 200 ° C. to 1000 ° C., and more preferably 400 ° C. to 800 ° C. By firing at this temperature, a sintered body of radium salt insoluble in water is stably and reliably fixed on the surface of the porous ceramic single body. Thereby, a high radon release rate can be obtained stably over a long period of time. When the firing temperature is lower than the above temperature, the radium salt is likely to be incompletely sintered, and stability and water resistance are hardly obtained. Moreover, when the firing temperature is higher than the above temperature, the radon release rate (release amount) tends to decrease.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described specifically and in detail with reference to the drawings.
First, a method for manufacturing a ceramic radon emission source will be described. 1A shows a manufacturing process of a ceramic radon emission source using a ceramic carrier made of SiC, and FIG. 1B shows TiO.₂Coated SiC (hereinafter “TiO”)₂-SiC ". The manufacturing process of the ceramic radon emission radiation source using the ceramics carrier which consists of) is shown.
[0013]
In any manufacturing method, first, a ceramic carrier made of a porous sintered body of SiC is made. There are several methods for producing such a ceramic carrier, and there is a method in which a porous organic substrate such as filter paper is impregnated with an inorganic polymer as a ceramic precursor and fired.
[0014]
First, a cylindrical filter paper is prepared and cut into an appropriate length. When a sufficient thickness cannot be obtained with a single layer of filter paper, apart from the cut cylindrical filter paper, the filter paper is cut with the same length, and this is cut into a band in the longitudinal direction by an appropriate width, The diameter is reduced by shortening the circumference. Then, the filter paper is inserted into another cylindrical filter paper in a cylindrical shape and fixed.
[0015]
Thereafter, the cylindrical filter paper is impregnated with an inorganic polymer that becomes a ceramic precursor such as polycarbosilane (PCS), and the cylindrical filter paper is dried. Thereafter, the cylindrical filter paper is fired to obtain a cylindrical porous SiC sintered body, which can be used as a ceramic carrier.
Further, a sol-like TiO 2 is formed on the ceramic carrier made of the porous SiC sintered body.₂TiO 2 by impregnating and drying this₂Can be obtained.
[0016]
There are also known methods using dry or wet molding. In the former, ceramic powder and a powder binder are uniformly mixed at an appropriate ratio, and this is pressure-molded into a predetermined shape in a mold. In the latter case, ceramic powder is uniformly mixed and dispersed in an organic binder dissolved in a solvent to form a ceramic slurry. This ceramic slurry is formed by means such as extrusion molding, cut into a predetermined length, and then dried. Thus, an unfired molded body is obtained. And this is baked to obtain a porous ceramic sintered body.
[0017]
As a means for firing the unfired ceramic molded body, a heat treatment in a general firing furnace, a discharge plasma sintering method (SPS method), or the like can be used. Before the molded body is fired, preliminary heat treatment may be performed to remove the binder. In any case, the above-mentioned filter paper or organic binder that holds the inorganic polymer that becomes the ceramic precursor or that binds the ceramic powder disappears, and the ceramic is sintered, so that the porous ceramic is sintered. A ceramic carrier composed of the aggregate is obtained.
The ceramic carrier thus produced is suitably a cylindrical one as shown in FIG.
[0018]
First, an example of a manufacturing process of a ceramic radon emission source using a SiC ceramic carrier will be described with reference to FIG.
As shown in FIG. 1 (a), a ceramic carrier made of a cylindrical porous SiC sintered body prepared as described above is prepared, and a Ra-226 solution is applied to the ceramic carrier using a syringe or a syringe. Then, the ceramic support is impregnated with the Ra-226 solution. In addition, a means for immersing and impregnating the ceramic support in the Ra-226 solution can be taken. Thereafter, the Ra solution is dried. As the Ra solution, RaCl₂An aqueous solution is preferred.
[0019]
Next, this ceramic carrier is₂SO_FourThe RaCl impregnated in the ceramic carrier by impregnating₂And H₂SO_FourReacts with RaSO, which is insoluble in water inside the ceramic carrier._FourProduces.
Thereafter, the ceramic carrier is heat-treated in air and fired. The firing temperature is preferably from 200 to 1000 ° C, particularly preferably from 400 to 800 ° C.
[0020]
RaSO held on the ceramic carrier by this firing process_FourIs sintered and fixed to a ceramic carrier made of porous SiC.
Through the above steps, RaSO is insoluble in water on the porous SiC ceramic support._FourA ceramic radon emission radiation source fixed in a sintered state can be obtained.
[0021]
Next, according to FIG.₂An example of a manufacturing process of a ceramic radon emission source using a SiC ceramic carrier will be described.
As shown in FIG. 1B, as described above, the SiC sintered body is made of TiO.₂Coated cylindrical porous TiO₂-Prepare a ceramic carrier made of a SiC sintered body, drop the Ra-226 solution onto the ceramic carrier using a syringe or syringe, and impregnate the ceramic carrier with the Ra-226 solution. Thereafter, the Ra aqueous solution is dried. This process is basically the same as the manufacturing process of the ceramic radon emission source using the SiC ceramic support described above.
[0022]
Next, this ceramic carrier_ThreeCOONH_FourOr (NH_Four)₂HC₆H_FiveO₇Impregnate. As a result, the RaCl impregnated in the ceramic support₂And CH_ThreeCOONH_FourOr (NH_Four)₂HC₆H_FiveO₇React with Ra (CH_ThreeCOO)₂Or RaHC₆H_FiveO₇Produces.
[0023]
Thereafter, the ceramic carrier is heat-treated in air and fired. By this firing step, the Ra (CH_ThreeCOO)₂Or RaHC₆H_FiveO₇TiO coated with ceramic carrier₂Reacts with RaTiO insoluble in water_ThreeThis is sintered and fixed on a ceramic carrier made of porous SiC.
Through the above steps, RaTiO insoluble in water on the ceramic support made of porous SiC._ThreeCan be obtained.
[0024]
In the above example, SiC ceramics or TiO is used as the ceramic carrier.₂-Although the example using SiC ceramic was demonstrated, other ceramics can also be used as a ceramic support | carrier. Ceramics suitable for fixing a Ra-266 sintered body as a ceramic radon emission source are resistant to radiation, chemically stable, and easily obtain a porous sintered body. As such, ZrO₂, Al₂O_Three, Nd₂O_Three, Nb₂O_Five, Si_ThreeN_Four, SiO₂Etc., or a ceramic of a mixture of them can be used.
[0025]
【Example】
Next, as an example of the present invention, a specific method for producing a ceramic radon emission source, an evaluation test of the produced ceramic radon emission source, and results thereof will be specifically described.
[0026]
Example 1
Cylindrical filter paper having an outer diameter of 20 mmφ was prepared and cut into two pieces having a length of 15 mm. One cylindrical filter paper having a length of 15 mm was cut into a band shape in the longitudinal direction by a small width, and the diameter was reduced by shortening the peripheral length, and this was inserted inside the other cylindrical filter paper.
[0027]
Next, the double cylindrical filter paper was impregnated with a hexane solution of polycarbosilane (PCS) and fired at a high temperature in an argon gas to obtain a ceramic carrier made of a porous SiC sintered body. . This ceramic carrier had an inner diameter of 9 mmφ, an outer shape of 12 mmφ, a length of 10 mm, a mass of 460 mg, and a volume of 0.49 ml.
[0028]
Next, as shown in FIG. 1 (a), RaCl is applied to the ceramic carrier made of the cylindrical porous SiC sintered body produced as described above.₂0.1 ml of an aqueous solution (43.79 KBq / g, 0.5 M HCl) was added dropwise, and RaCl₂A ceramic carrier was impregnated with an aqueous solution. Thereafter, the ceramic carrier was dried on a hot plate at a temperature of 100 ° C. or lower.
[0029]
Next, 0.024 μmol of H is added to the ceramic carrier.₂SO_FourWas impregnated uniformly. As a result, RaSO is insoluble in water in the ceramic support._FourGenerated. These ceramic carriers were divided into three groups and each was heat-treated in air at temperatures of 400 ° C., 600 ° C., and 800 ° C. As a result, RaSO_FourCeramic radon emission source (RaSO) fixed to a porous SiC ceramic carrier_Four/ SiC) was completed.
[0030]
Using this ceramic radon emission source, radon emission was measured by a flow method. The measurement of radon emission by this flow method is done by storing the ceramic radon emission source in a closed sealed container, introducing a constant amount of air into this space every hour, and in the air discharged from the other of the sealed containers. The concentration of radon contained in the product is measured, and the emission rate and concentration of radon emitted from the ceramic radon emission source are obtained from the measured value.
[0031]
FIG. 2 shows an outline of this measuring apparatus. The ceramic radon emission source S is accommodated in the sealed container 3. Air is drawn into the flow path by being depressurized at the end of the flow path by the pump 8. This air is first passed through the dehumidifying tube 1 to be dehumidified, and then the flow rate is controlled by the mass flow controller 2, and is introduced to one end side of the sealed container 3 through the valve 9 at a predetermined flow rate per hour. A radon monitor 4 is connected to the other end side of the sealed container 3 via a valve 10.
[0032]
The mass flow controller 2 and the land monitor 4 are connected by a bypass line that does not pass through the sealed container 3 via valves 11 and 12. When the valves 9 and 10 are closed to separate the sealed container 3 from the flow path and the work such as replacement of the ceramic radon emission source S is performed, the valves 11 and 12 are opened and air is allowed to flow through the bypass line.
[0033]
The air containing radon sent from the sealed container 3 is sent to the radon monitor 4 and the radon in the air is detected by the radon monitor 4 while the pressure is measured by the baratron 5 and the radon concentration in the air is measured. Is done. Further, the radon-containing air is trapped by the activated carbon filter 7 through the flow monitor 6 for measuring the flow rate, and the air not containing radon is exhausted through the pump 8.
[0034]
As a result of measurement by such a flow method, the relationship between the radon release rate determined by the radon concentration measured by the radon monitor 4 and the sintering temperature is shown by a solid line in FIG. Here, the radon emission rate is expressed as a ratio between the radioactivity that radium impregnated in the ceramic radon emission source S should have and the radioactivity of radon measured by the radon monitor 4.
[0035]
As is clear from FIG. 3, the radon release rate is higher as the sintering temperature in the manufacturing process is lower. These radon release rates are much higher than the comparative examples described later.
It has been confirmed that when the sintering temperature is less than 400 ° C., the radium salt is hardly sintered, so that the fixing rate of radium to the porous ceramic carrier is deteriorated. When the sintering temperature is increased, the fixing property of the radium salt to the ceramic carrier is improved, but the radon release rate is decreased. As shown in FIG. 3, when the sintering temperature is 800 ° C. or less, a high radon release rate of 10% or more, specifically 12.7%, is realized.
[0036]
4 to 6 are graphs in which the radon concentration measured by the radon monitor 4 in the radon release test is plotted at regular intervals. 4 is a ceramic radon emission source sintered at a sintering temperature of 400 ° C., FIG. 5 is a ceramic radon emission source sintered at a sintering temperature of 600 ° C., and FIG. This is a ceramic radon emission source.
[0037]
As is clear from these figures, there is a difference in the level of radon concentration detected depending on the difference in sintering temperature, but in any ceramic radon emission radiation source, radon release within tens of minutes to 2 hours from the start of the test. The concentration is in a steady state, and then a stable and constant radon concentration is measured.
[0038]
FIG. 12 shows the aforementioned RaSO._FourIt is the graph which showed the elution rate of the radon eluted in water when the / SiC ceramic radon emission source was immersed in water by the relationship with immersion time. The two-dot chain line is sintered at a sintering temperature of 400 ° C., the solid line is sintered at a sintering temperature of 600 ° C., and the broken line is sintered at a sintering temperature of 800 ° C.
[0039]
Here, a container in which 100 ml of pure water is placed in a constant temperature bath set at 20 ° C. is allowed to stand, and RaSO is added to the water in the container._Four/ SiC ceramic radon emission source is immersed for 30 minutes. Thereafter, the same line source is pulled up from the pure water, and Ra-226 of 20 ml of water separated from the container is measured with a Ge semiconductor detector. Then return the dispensed water to the original container and the same RaSO_FourThe SiC ceramic radon emission source is also immersed in water for 30 minutes. Thereafter, the radon emission source is taken out of the water, and Ra-226 of water is measured in the same manner. Thereafter, the radon emission source was immersed in water for 30 minutes and the measurement of Ra-226 was repeated.
[0040]
The dissolution rate was calculated by calculating the amount of Ra-226 that flowed into 100 ml of pure water contained in the container from the above measured values, and was expressed as a ratio with the amount of Ra-226 impregnated in the ceramic support.
As is apparent from FIG. 12, any RaSO_Four/ SiC ceramic radon emission source also shows an increase in the elution amount for about 3 hours from the start of immersion, but almost no increase in the elution amount thereafter, and the elution amount after 20 hours is a maximum of 40%. is there.
[0041]
(Example 2)
A sol-like TiO 2 is formed on a cylindrical ceramic support made of a porous SiC sintered body produced in the same manner as in Example 1.₂TiO 2 by impregnating and drying₂A ceramic carrier coated with is obtained. This ceramic carrier has an inner diameter of 9 mmφ, an outer shape of 12 mmφ, a length of 10 mm, a mass of 460 mg, and a volume of 0.49 ml.
[0042]
Next, as shown in FIG. 1 (b), RaCl is added to the ceramic carrier.₂0.1 ml of an aqueous solution (43.79 KBq / g, 0.5 M HCl) was added dropwise, and RaCl₂A ceramic carrier was impregnated with an aqueous solution. Thereafter, the ceramic carrier was dried on a hot plate at a temperature of 100 ° C. or lower.
[0043]
Next, 0.024 μmol of CH is added to the ceramic carrier._ThreeCOONH_FourWas impregnated uniformly. Thereafter, the ceramic carriers were divided into three groups, each of which was heat-treated at 600 ° C., 800 ° C., and 1000 ° C. for 1 hour in the air and fired. As a result, Ra (CH) impregnated inside the ceramic carrier_ThreeCOO)₂Is TiO₂Reacts with RaTiO_ThreeThe ceramic radon emission source (RaTiO) which is sintered and fixed on the ceramic carrier_Three/ SiC) was obtained.
[0044]
Next, using this ceramic radon emission source, the RaSO of Example 1 was used._FourAs in the case of the / SiC ceramic radon emission source, the measurement apparatus shown in FIG. 2 was used, and the radon emission amount was measured by the flow method.
As a result of measurement by such a flow method, the relationship between the radon release rate determined from the radon concentration measured by the radon monitor 4 and the sintering temperature is shown by a broken line in FIG.
[0045]
As is apparent from FIG. 3, the radon release rate is higher as the sintering temperature is lower. When the sintering temperature is increased, the fixing property of the radium salt to the ceramic carrier is improved, but the radon release rate is decreased. As shown in FIG. 3, when the sintering temperature is 800 ° C. or less, a high radon release rate of 10% or more, specifically 19.7% or more is realized. However, when the sintering temperature reached 1000 ° C., the radon release rate was 2.3%, which was 10% or less. However, these radon release rates all show higher values than the comparative examples described later.
[0046]
7 to 9 are graphs in which the radon concentration measured by the radon monitor 4 in the radon release test is plotted at regular intervals. 7 is a ceramic radon emission source sintered at a sintering temperature of 600 ° C., FIG. 8 is a ceramic radon emission source sintered at a sintering temperature of 800 ° C., and FIG. This is a ceramic radon emission source.
[0047]
As shown in FIGS. 7 and 8, in any ceramic radon emission radiation source, the radon emission concentration becomes a steady state in less than one hour from the start of the test, and thereafter a stable and constant radon concentration is measured. However, as shown in FIG. 9, in the ceramic radon emission radiation source processed at a sintering temperature of 1000 ° C., the radon emission concentration was lower than in the ceramic radon emission radiation source processed at a sintering temperature lower than that.
[0048]
FIG. 13 shows the RaSO of Example 1._Four/ SiC ceramic radon emission source, RaTiO_ThreeIt is the graph which showed the elution rate of the radon eluted in water when the / SiC ceramic radon emission source was immersed in water by the relationship with immersion time. The two-dot chain line is sintered at a sintering temperature of 600 ° C., the solid line is sintered at a sintering temperature of 800 ° C., and the broken line is sintered at a sintering temperature of 1000 ° C.
[0049]
As is apparent from FIG. 13, any RaTiO_ThreeEven with the / SiC ceramic radon emission source, the elution amount increased for about 3 hours from the start of immersion, but there was almost no increase in the elution amount thereafter. The amount of elution after 20 hours was 12% or less at maximum, and the RaSO of Example 1 was used._Four/ The elution rate was lower than that of the SiC ceramic radon emission source.
[0050]
(Comparative example)
For comparison, FIG. 10 and FIG. 11 show that the radon solution measured by the radon monitor 4 is measured at regular intervals using a radon solution simply dropped on a plate and dried. It is a graph plotted in. FIG. 10 shows a 0.1 ml plate impregnated with a 43.79 KBq / g, 0.5 M HCl aqueous solution of Ra-266 and dried at 120 ° C. Moreover, FIG. 11 shows 43.79KBq / g, 0.5M-H.₂SO_FourA 0.1 ml plate was impregnated with an aqueous solution of Ra-266 and dried at 200 ° C.
[0051]
As is clear from FIGS. 10 and 11, in both cases, a certain level of radon concentration was measured immediately after the start of the test, but almost no radon concentration could be measured after 1 to 4 hours from the start of the test. This is presumably because the surface area of the radium emission radiation source is extremely small if the radium solution is simply dried, so that only radon emission from the surface occurs and no emission from the inside occurs.
[0052]
Furthermore, when the radium solution was simply dropped on the plate and dried, it was immersed in water in the same manner as in Example 1 and a dissolution test for radium in water was performed. As a result, 90% was obtained in the first 30 minutes. The above elution rate of radium has been confirmed. That is, it was confirmed that the radium solution simply dropped on the plate and dried had poor water resistance.
[0053]
【The invention's effect】
As described above, according to the present invention, a radium salt insoluble in water is sintered and fixed on a porous ceramic carrier, so that a high concentration of radon gas can be stably released over a long period of time. A ceramic radon emission source that is easy to handle and has high water resistance can be obtained. In other words, it has a high release property that releases a high concentration of radon gas, a long-term experiment, a stable release of a high concentration of radon gas, an easy handling, a high stability in water resistance and radiation resistance, etc. Therefore, it is possible to obtain a ceramic radon emission source satisfying the characteristics required in the field of research on exposure effects to living bodies due to the above.
[Brief description of the drawings]
FIG. 1 RaSO_Four/ SiC ceramic radon emission source and RaTiO_ThreeIt is the schematic which shows the example of the process of manufacturing a / SiC ceramic radon emission ray source.
FIG. 2 RaSO_Four/ SiC ceramic radon emission source and RaTiO_ThreeIt is a piping system diagram which shows the example of the apparatus which measures those radon emission characteristics by a flow system about / SiC ceramics radon emission source.
FIG. 3 RaSO_Four/ SiC ceramic radon emission source and RaTiO_ThreeIt is a graph which shows the relationship between the radon discharge | release amount measured by the measuring apparatus shown in FIG. 3, and the sintering temperature of these radiation sources using / SiC ceramic radon discharge | release source.
FIG. 4 RaSO treated at a sintering temperature of 400 ° C._FourFIG. 4 is a graph showing the relationship between radon concentration and time measured by the measuring device of FIG. 3 using a / SiC ceramic radon emission source.
FIG. 5: RaSO treated at a sintering temperature of 600 ° C._FourFIG. 4 is a graph showing the relationship between radon concentration and time measured by the measuring device of FIG. 3 using a / SiC ceramic radon emission source.
FIG. 6: RaSO treated at a sintering temperature of 800 ° C._FourFIG. 4 is a graph showing the relationship between radon concentration and time measured by the measuring device of FIG. 3 using a / SiC ceramic radon emission source.
FIG. 7: RaTiO processed at a sintering temperature of 600 ° C._ThreeFIG. 4 is a graph showing the relationship between radon concentration and time measured by the measuring device of FIG. 3 using a / SiC ceramic radon emission source.
FIG. 8: RaTiO processed at a sintering temperature of 800 ° C._ThreeFIG. 4 is a graph showing the relationship between radon concentration and time measured by the measuring device of FIG. 3 using a / SiC ceramic radon emission source.
FIG. 9: RaTiO processed at a sintering temperature of 1000 ° C._ThreeFIG. 4 is a graph showing the relationship between radon concentration and time measured by the measuring device of FIG. 3 using a / SiC ceramic radon emission source.
FIG. 10 shows RaCl for comparison.₂It is a graph which shows the relationship between the radon density | concentration measured with the measuring apparatus by FIG. 3 and time using the radon emission source which dripped the solution on the plate and dried.
FIG. 11: RaSO for comparison_FourIt is a graph which shows the relationship between the radon density | concentration measured with the measuring apparatus by FIG. 3 and time using the radon emission source which dripped the solution on the plate and dried.
FIG. 12 RaSO_FourIt is a graph which shows the relationship between the elution rate of radium when a / SiC ceramic radon emission radiation source is immersed in water, and immersion time.
FIG. 13 RaTi_ThreeIt is a graph which shows the relationship between the elution rate of radium when a / SiC ceramic radon emission radiation source is immersed in water, and immersion time.

Claims (5)

A radon emission source that emits radioactive radon gas, in which radioactive radium insoluble in water is fixed on a ceramic carrier made of porous ceramics, and the ceramic carrier is a porous sintered body of SiC or TiO _2. Ceramics radon emitting radiation source, wherein the porous sintered body der Rukoto of coated SiC and. 2. The ceramic radon emission source according to claim 1 , wherein the radioactive radium is fixed on the ceramic carrier in the form of a salt insoluble in water. A method for producing a radon emission source that emits radioactive radon gas, a first step of obtaining a ceramic carrier made of porous ceramics, a second step of impregnating the ceramic carrier with a radioactive radium solution, and a ceramic carrier a third step of depositing a salt of the radioactive radium water-insoluble in, to sinter radium salt of the insoluble, have a a fourth step of fixing the ceramic carrier, the ceramic carrier is a porous SiC Sintered body or TiO ₂ Method of manufacturing a ceramic radon emitting radiation source, wherein the porous sintered body der Rukoto of coated SiC and. 4. The method for producing a ceramic radon emission source according to claim 3 , wherein the radioactive radium is fixed on the ceramic carrier in the form of a salt insoluble in water. The method for producing a ceramic radon emission source according to claim 3 or 4 , wherein the sintering temperature of the radium salt is 200 ° C to 1000 ° C.

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