JPH11194192A - Insulator for reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulator for a reactor capable of obtaining a higher insulation effect. SOLUTION: Insulator is constituted by including an insulator body 32 and a glass film 36 wherein pigment particles 40 having high emissivity of about 0.95 is dispersed in glass structure 38 which is placed on the surface 34 on the high temperature coolant reservoir side 24 of the insulator 32. As the glass film 36 wherein pigment particles 40 are dispersed in the glass structure 38 is placed on the surface 34 of the high temperature coolant reservoir 24 side of the insulator body 32, high emissivity is given to the surface 34 of the insulator 30 in the high temperature coolant reservoir 24 side according to the emissivity of the glass film 36 determined by the emissivity of the pigment particles 40. Therefore, the heat transmitted from the high temperature coolant reservoir 24 to the insulator 30 is absorbed by the glass film 36 and efficiently returned by radiation into the high temperature coolant reservoir 24, so that the heat absorbed by the insulator 30 and radiated out through it is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a heat insulating material used for a nuclear reactor such as a fast breeder reactor.

[0002]

2. Description of the Related Art In a nuclear reactor in which heat energy based on a nuclear reaction in a reactor core arranged in a reactor vessel is taken out and used by a cooling system, radiation generated by the nuclear reaction is prevented from leaking to the outside. For this purpose, the reactor vessel is covered with a physiological shielding material made of, for example, reinforced concrete. FIG. 1 is a diagram schematically showing a configuration of a main part of a fast breeder reactor, which is a type of nuclear reactor. In the figure, a reactor core 12 is provided in a reactor vessel 10, and a primary coolant supply pipe 16 and a primary coolant discharge pipe 18 for supplying and discharging a coolant 14 through a path passing through the reactor core 12 are provided. The upper part is closed with a physiological shielding material 20 made of reinforced concrete for shielding the inside of the furnace from the outside atmosphere. Further, the reactor vessel 10 includes a low-temperature coolant storage section 22 located below the core 12 for storing the low-temperature coolant 14 sequentially supplied from the supply pipe 16, and a core 12.
It is separated from a high-temperature coolant storage section 24 which is located above the high-temperature coolant 14 and stores the high-temperature coolant 14 warmed by the core 12. Note that, for example, in a fast breeder reactor, liquid metal sodium is used as the coolant 14 because it does not attenuate neutron energy involved in a nuclear reaction and has a high heat removal capability.

[0003]

The coolant 14 in the high-temperature coolant storage section 24 that has absorbed the heat energy has a high temperature of, for example, about 400 to 450 (° C.). As shown in the drawing, a heat insulating material (heat shielding material) 26 is provided between the cooling material 14 and the physiological shielding material 20 for the purpose of protecting the vapor from the cooling material 14 (for example, sodium vapor). That is, the physiological shielding material 20
Is an excellent shielding material for neutron rays and gamma rays which have a large effect on living bodies, but when heated to a high temperature, water leakage, cracks, etc. occur, and the shielding effect is impaired. Therefore, since it is necessary to maintain the temperature at a low temperature of about 20 to 30 (° C.), the heat insulating material 26 is provided.

Conventionally, as described in Japanese Patent Application Laid-Open No. Sho 60-218093, the above-mentioned heat insulating material 26 is made of silicon carbide, mullite, or the like having high heat insulating properties (ie, low heat conductivity).
A plate made of a ceramic material such as steatite or beryllium porcelain is coated with, for example, stainless steel. According to the heat insulating material 26 having such a structure,
Since the ceramic material has high heat insulating property due to its low thermal conductivity, the thickness required for obtaining the heat insulating effect as described above is reduced to about 1/7, for example, as compared with the heat insulating material made entirely of stainless steel. , The weight is also reduced to about 1/10. For this reason, there is an advantage that the downsizing of the nuclear reactor is facilitated in combination with the simplification of the support structure of the heat insulating material 26. However, since such a heat insulating material 26 also needs to have a thickness of, for example, 900 (mm) or more, it has been desired to further reduce the thickness of the heat insulating material in order to further reduce the size of the nuclear reactor. .

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat insulating material for a nuclear reactor capable of obtaining a higher heat insulating effect.

[0006]

In order to achieve the above object, the gist of the present invention is to pass through a low-temperature coolant storage section, a reactor core, and a high-temperature coolant storage section provided in a reactor vessel. In a reactor in which the coolant is heated to a high temperature based on a nuclear reaction in the core in a process in which the coolant is successively circulated, in the high-temperature coolant storage section in which the coolant heated to a high temperature is stored. (A) a heat insulating material body having a predetermined thickness, and (b) the heat insulating material provided outside the high-temperature coolant storage portion to suppress heat transfer from the heat insulating material to the surroundings. A glass film provided on a surface of the main body on the side of the high-temperature coolant storage section and having pigment particles having a predetermined emissivity dispersed in a glass structure.

[0007]

According to the present invention, the heat insulating material body having a predetermined thickness and the pigment particles having a predetermined emissivity provided on the surface of the heat insulating material body on the side of the high-temperature coolant storage portion are contained in the glass structure. The heat insulating material for a nuclear reactor includes the dispersed glass film. Therefore, since the glass film in which the pigment particles are dispersed in the glass structure is provided on the surface of the heat insulating material body on the high-temperature coolant storage side, the emissivity of the glass film determined according to the emissivity of the pigment particles is provided. Accordingly, a high radiation ability is imparted to the surface of the heat insulating material for a reactor on the high-temperature coolant storage part side. Therefore, the heat transferred from the high-temperature coolant storage unit to the heat insulating material for the nuclear reactor is absorbed by the glass film and efficiently returned to the high-temperature coolant storage unit by radiation, so that the heat is absorbed by the heat insulating material for the nuclear reactor. , And the amount of heat released through it to the outside is reduced. As a result, the heat insulating effect is substantially enhanced, so that the thickness of the heat insulating material for a nuclear reactor required to obtain the same heat insulating effect can be made smaller than before.

[0008]

In another embodiment of the present invention, preferably, the glass film is provided so as to cover the pigment particles at an interface between the pigment particles and the glass structure, and has a value larger than a value in the glass structure at the interface. It has a pigment coating layer of a predetermined thickness containing silicon dioxide at a high content. In this way, the glass film provided on the surface of the heat insulating material for a nuclear reactor is
A pigment coating layer provided at the interface between the pigment particles and the glass structure and covering the pigment particles, the pigment coating layer having a predetermined thickness containing silicon dioxide at a content higher than the value in the glass structure at the interface; You. Therefore, the interface between the pigment particles and the glass structure is provided with a pigment coating layer having a relatively low reactivity with the pigment particles due to a higher content of silicon dioxide than the glass structure. During the firing for providing the glass film on the surface of the heat insulating material and during the use of the nuclear reactor, the interface reaction between the pigment particles and the glass structure, the oxidation of the pigment particles, and the like are preferably performed by the pigment coating layer provided at the interface. Is suppressed. Therefore, the original emissivity of the pigment particles is utilized in the glass structure as it is, and even during use at high temperatures, a decrease in the emissivity of the pigment particles due to an interface reaction or oxidation is suppressed,
A higher emissivity is imparted and maintained to the glass film and thus to the heat insulating material for a nuclear reactor, and a higher heat insulating effect is obtained and maintained.

According to the findings of the present inventors, if the reaction between the glass structure and the pigment particles occurs due to the above-mentioned firing process of the glass film or exposure to a high temperature during use, the emissivity of the pigment particles is reduced. And the heat resistance of the glass film is reduced. It is also known that the emissivity decreases when the pigment particles are oxidized. Therefore, when pigment particles are dispersed in a glass structure for the purpose of utilizing a high emissivity, it is important to suppress the above reaction and oxidation. Note that, for example, U.S. Pat.
No. 4,093,771 discloses a technique of rapid heating in a firing process for forming a glass film. However, in such a rapid heating method, the effect of suppressing the above reaction in the firing process is insufficient, and the necessity of suppressing the reaction during use is not considered at all.

Preferably, the heat insulating material main body is made of ceramics. In this case, since the heat insulating material body is made of ceramics, the nuclear reactor provided with the glass film is provided based on the high heat insulating properties of ceramics having a lower thermal conductivity than metal materials such as stainless steel. The heat insulating property of the heat insulating material for use is further enhanced, and the thickness required for obtaining a predetermined heat insulating effect can be further reduced. More preferably, the ceramics include silicon nitride, silicon carbide,
Mullite is used alone or in combination. These are preferable as heat insulating materials because they have low reactivity with a coolant composed of sodium or the like and have high creep resistance. When silicon nitride or silicon carbide is used, it is preferable to use a porous structure in order to obtain a higher heat insulating property. For example, the structure may be a honeycomb shape or a lotus root shape.

[0011] Preferably, the pigment coating layer contains silicon dioxide in an amount of 85 (wt%) or more. In this case, since the content of silicon dioxide is sufficiently high, the interfacial reaction between the pigment particles and the glass structure is further suppressed.

[0012] Preferably, the pigment coating layer comprises 100
It is provided with a thickness of about to several hundred (nm). With this configuration, the thickness of the pigment coating layer is sufficiently large within a range that does not significantly affect the thermal characteristics such as the softening point and the coefficient of thermal expansion of the glass film. The reaction is more reliably suppressed.

Preferably, the pigment particles are silicon borides such as silicon tetraboride (SiB ₄ ), silicon hexaboride (SiB ₆ ), or silicon tetraboride (SiB ₁₄ ), or molybdenum disilicide. (MoSi
₂ ), at least one of silicon carbide and iron oxide. In this case, since these have sufficiently high emissivity, the emissivity of the glass film is further increased, and the heat insulation of the heat insulating material for a nuclear reactor is further enhanced. More preferably, the pigment particles are silicon borides. In this way, since the silicon boride has an extremely high emissivity, it is more preferably used as the pigment particles constituting the glass film. And the effect of providing the pigment coating layer is more remarkably obtained.

Preferably, the pigment particles have an average particle diameter of about 1 to 100 (μm). In this case, since the average particle diameter is sufficiently increased, the reactivity with the glass structure is further reduced, and the decrease in the emissivity of the pigment particles is further suppressed. Dispersibility in the glass film is increased. If the average particle diameter is larger than 100 (μm), the particles are substantially unevenly distributed in the glass film, so that a sufficiently high emissivity cannot be obtained.

Preferably, the pigment particles are contained in the glass film at a ratio of 2 (wt%) or more. In this case, since the pigment particles are sufficiently contained in the glass film, the contribution of the pigment particles to the emissivity of the glass film is sufficiently increased, and the emissivity of the glass film is sufficiently increased. Thus, the heat insulating properties of the heat insulating material for a nuclear reactor can be sufficiently enhanced.

Preferably, the glass film is provided on the surface of the heat insulating material for a nuclear reactor with a thickness of 0.5 (mm) or less.
In this case, since the radiation is generated mainly in the vicinity of the surface of the glass film, the glass film does not need to be so thick. On the other hand, it is easy to provide a uniform thickness by making it sufficiently thin. .

Preferably, the glass structure is made of aluminosilicate glass, high-purity silica glass (for example, quartz glass), or the like. Since these glasses have high heat resistance and high thermal shock resistance, a glass film more suitable as a coating of a heat insulating material in a nuclear reactor vessel requiring high safety can be obtained. In addition, these glasses have B ₂ O ₃ , P ₂ O ₅ , PbO, K ₂ O, Na ₂ O, CaF ₂ , NaF, Li
It is preferable to add flux components such as ₂ O and LiF. However, these flux components are inherently chemically stable silica-glass modifying groups and can significantly reduce their corrosion resistance. To increase the reactivity of the glass film with time, that is, to cause erosion by the coolant,
It is desirable to keep the amount of addition to about 2 to 10 (wt%).

More preferably, the glass structure is made of borosilicate glass. By doing so, the borosilicate glass containing silicon dioxide as a main component and containing boric acid has particularly high heat resistance and thermal shock resistance among the glasses, so that higher safety is required because higher safety is required. A glass film which is more suitable as a coating for a heat insulating material for a nuclear reactor which requires high thermal shock resistance and high radiation properties can be obtained. Examples of such borosilicate glass include, for example, reaction cured glass (for example, reaction cured glass obtained by adding boron oxide to high-purity silica glass having a silicon dioxide content of about 96% and adding a number (%) thereof). U.S. Pat. No. 4,093,771), borosilicate glass having a silicon dioxide content of about 81 (%), and the like are preferably used. In the former, too, boron oxide is added and fired, so that boron is infiltrated into the surface of the high-purity silica glass particles to form a borosilicate layer. Therefore, in any glass, the silicon dioxide content of the glass structure near the interface with the pigment particles is
Since it is only about 80 (%), if the silicon dioxide content of the pigment coating layer is set to about 85 (%) as described above, a sufficient effect of suppressing the interfacial reaction can be obtained. It is desired that the borosilicate glass has as high a silicon dioxide purity as possible from the viewpoint of heat resistance, and alkali metals such as sodium (Na) and potassium (K) and magnesium ( Mg), alkaline earth metals such as calcium (Ca), and iron (Fe), titanium (Ti),
Lead (Pb), etc. is as low as possible, and more preferably 1 (wt
%).

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, the dimensional ratios and the like of each part are not necessarily drawn accurately.

FIG. 2 is a diagram schematically showing a cross-sectional structure of a heat insulating material for a nuclear reactor (hereinafter, simply referred to as a heat insulating material) 30 according to one embodiment of the present invention. In the figure, a heat insulating material 30 corresponds to FIG.
Is used in place of the heat insulating material 26 in the nuclear reactor vessel 10 shown in FIG. 1 and includes, for example, a flat heat insulating material body 32 made of ceramics and having a thickness of about 820 (mm), Surface 34 on high-temperature coolant storage section 24 side
And a glass film 36 having a thickness of about 0.4 (mm) provided so as to cover the glass.

The heat insulating material main body 32 is made of, for example, a silicon nitride / cordierite composite material having high heat resistance and low heat conductivity, and has a heat conductivity of 5 (W / m ·
It has characteristics of about K), bending strength of about 370 (MPa), and density of about 2.7 (g / cm ³ ). The heat insulating material main body 32 is made of, for example, silicon nitride powder (for example, E-10 manufactured by Ube Industries, Ltd.).
Etc.) and a cordierite powder (for example, KYORIX manufactured by Kyoritsu Ceramics Co., Ltd.) added at a ratio of about 30 (wt%) to form a flat plate using a vibration press or the like.
It is manufactured by firing in a nitrogen gas atmosphere at about 1400 (℃) for about 4.5 hours.

Further, as shown in the figure, the glass film 36 is composed of a glass structure 38 and pigment particles 40 substantially uniformly dispersed in the glass structure 38. The glass structure 38 is, for example, a reaction hardened glass described in U.S. Pat. No. 4,093,771 as described in a manufacturing process described later, and is entirely made of borosilicate glass, for example, 2 × 10 ⁻⁶ (/ (° C.), but is composed of a high-purity silica-containing borosilicate glass having a purity of about 96 (wt%) which forms the nucleus of the glass structure 38 derived from the high-purity silica glass described later. It is composed of a porous portion 38b and a dense portion 38a produced from the high-purity silica glass and boron oxide and having a silica content of about 82 (wt%).

The pigment particles 40 are, for example, silicon tetraboride (Si) having an average particle size of about 40 (μm) and an emissivity of about 0.95.
B ₄ ), which is contained in the glass film 36 at a ratio of about 2.5 (wt%). At the periphery of the pigment particles 40, that is, at the interface with the glass structure 38, for example, 100 to several hundreds (nm)
A moderately thick silica glass layer 42 is provided.
The silica glass layer 42 is made of, for example, high-purity silica glass having a purity of about 99 (%), and in the present embodiment, this corresponds to a pigment coating layer. That is, the silica-glass layer 42, that is, the pigment coating layer has a higher silica content than the dense portion 38a located near the interface with the pigment particles 40 in the glass structure 38. Therefore, since the interfacial reaction between the pigment particles 40 and the glass structure 38 is suppressed, the glass film 36 is, for example, 500 (° C.)
0.9 or more at a high temperature of about 0.
It has high emissivity of 8 or more and high heat resistance of 1350 (° C) or more. Thus, the glass film 3
Since the high emissivity is imparted to the heat insulating material 30, the heat insulating material 30 has an emissivity to the high-temperature coolant storage part 24 side where the glass film 36 is provided. Since the heat is hardly absorbed by the heat treatment, the heat insulating property is substantially improved as compared with the case where the glass film 36 is not provided.

Incidentally, the glass film 36 configured as described above is provided on the surface 34 of the heat insulating material main body 32, for example, according to the process shown in FIG. Hereinafter, the film forming method will be described with reference to the drawings.

First, in the RCG manufacturing step of step 1A, a reaction hardened glass raw material powder is manufactured from a glass frit. This RCG manufacturing process is shown in detail in FIG. 4, for example. In FIG. 4, in the boron oxide dissolving step of step A1, for example, a boron oxide powder having a purity of 5N (99.999% or more) (for example, manufactured by Furuuchi Chemical Co., Ltd.) is heated to 85 (° C.).
It is dissolved in ion-exchanged water heated to a certain degree to produce a boron oxide aqueous solution. Next, in the solvent addition step of step A2, for example, ethanol (preferably a special grade reagent, for example, manufactured by Kanto Scientific Co., Ltd.) is added to the boron oxide aqueous solution,
In the glass / frit mixing step of step A3, high-purity silica / glass / frit is further added to the aqueous solution to produce a slurry. At this time, the amount of the boron oxide powder added to the silica / glass / frit is about 8 (wt%). In addition, as high-purity silica glass frit,
For example, SiO ₂ 96 (%), B ₂ O ₃ 3 (%), Al ₂ O ₃ 0.4 (%)
Porous two-component glass (eg, Vycor # manufactured by Corning International Co., Ltd.) having a composition of the order, a specific surface area of 200 (m ² / g), and a porosity of about 28 (%).
7930). Then, in the stirring step of step A4, the mixture is stirred while keeping the temperature at about 85 (° C.) on a hot plate or the like to remove ethanol and moisture in the slurry.

In the drying step of Step A5, Step A4
The slurry whose viscosity has been increased to such an extent that ethanol and water have been removed to some extent and difficult to stir is placed in an oven or the like and further dried at about 70 (° C.) to remove residual ethanol and water. After the drying is completed in this manner, the dried product is loosened by hand in the crushing step of step A6, and further classified in a classifying step of step A7 using a sieve of about # 16 to obtain, for example, 1 (m
m) Remove coarse particles larger than about m). In the firing step of step A8, the crushed and classified dried product is placed in a silica container having a purity of about 63 (%), and is, for example, 1000 to 1100 (° C.) × 2 (h).
r) Bake at about the same conditions. As a result, the high-purity silica glass frit reacts with boron oxide. Then, in the pulverizing step of step A9, the glass frit formed into a lump by firing is put into a pot type ball
Pulverized using a mill or the like, and finally classified in a classifying step of step A10 using a sieve of about # 330 to # 300.
By removing coarse particles of about (μm) or more, a reaction-hardened glass raw material powder can be obtained.

Returning to FIG. 3, in the pigment coating step of Step 1B, the pigment particles 40, ie, silicon tetraboride [# 200 mesh under product such as B-1088 manufactured by CERAC, USA) have an average particle diameter of about 40 (μm). ] With a high-purity silica-glass film. This pigment coating step is shown in detail in FIG. First, in the inorganic polymer dilution step of the step B1, for example, a preceramic polymer (an inorganic polymer that becomes a ceramic by heat treatment) perhydropolysilazane (for example, manufactured by Tonen Co., Ltd.) is mixed with a solvent such as xylene or the like. Dilute to a concentration of about 10 (wt%). Perhydropolysilazane is composed of silicon, nitrogen and hydrogen, and has a structure as shown in FIG. 6, for example, having a molecular weight of about 600 to 900 and a density of about 1.3 (g / cm ³ ). And has a very high purity with an impurity amount of several (ppm) or less.

In the pigment particle dispersing step of step B2, the pigment particles having a purity of 98 are contained in the diluted inorganic polymer liquid.
(%) 10 to 20 parts of the above silicon tetraboride with respect to the inorganic polymer liquid.
(wt%) and mix with a vibrating mill, etc.
Stir for about a minute to prepare a dispersion in which the pigment particles 40 are dispersed. In the subsequent spray drying step B3, the dispersion is sprayed with a spray drier or the like and dried with hot air. At this time, the spray drying conditions are, for example, a hot air inlet temperature of about 110 (° C.) and an outlet temperature of about 70 (° C.). Thereby, the inorganic polymer liquid attached to the surface of the pigment particles 40 is dried and condensed, and an inorganic polymer film is formed on the surface. Then, in the heat treatment step of step B4, heat treatment is performed, for example, in the atmosphere at about 400 (° C.). Thereby, silicon in the inorganic polymer film is combined with oxygen in the atmosphere to generate silicon dioxide (silica), and nitrogen and hydrogen in the inorganic polymer film are combined with ammonia (NH _3). ) Is generated and dissipated. For this reason, an extremely high-purity silica glass film formed from the inorganic polymer film is formed on the surface of the pigment particles 40 to a thickness of, for example, about 100 to several hundreds (nm). In addition,
The pigment particles 40 are, for example, pulverized by a ball mill and then classified using a # 200 mesh or the like. In this embodiment, steps B1 to B3 correspond to the inorganic polymer film forming step, the heat treatment step of step B4 corresponds to the heat generation step, and the silica-glass film corresponds to the pigment coating film.

Returning to FIG. 3, in the mixing step of step 2, pigment particles 40 obtained by applying a silica glass film to the reaction-cured glass raw material powder prepared as described above, for example, for 2.
5 (wt%), ion-exchanged water and a PVA (polyvinyl alcohol) aqueous solution are added, and the mixture is placed in an alumina porcelain pot with alumina cobblestone and hermetically sealed. Rotate about to mix. As a result, a paste (slurry) in which the reaction-hardened glass raw material powder and the pigment particles 40 are dispersed is obtained. The addition amounts of the ion-exchanged water and the PVA aqueous solution are appropriately determined so as to obtain a suitable viscosity. In the subsequent application step 3, the paste (coating slurry) discharged from the pot is vacuum-defoamed, filled in a spray gun, and applied to the surface 34 of the heat insulating material main body 32 by 0.4 (mm).
Spray-coat to a thickness of about At this time,
The discharge pressure is set to, for example, about 3 (kgf / cm ² ) or less. Then, after sufficiently drying at room temperature, for example, in the baking step of step 4, the coating film is subjected to a heat treatment at about 1200 (° C.) × 4.5 hours while flowing nitrogen (N ₂ ) gas in an atmosphere furnace, for example. The above-mentioned glass film 36 is generated. The heating rate in the baking step is, for example, 200 (° C.
/ Hr). Therefore, pigment particles 40 are contained in the glass structure 38 constituting the glass film 36 in a state of being covered with the silica-glass film, and this silica-glass film constitutes the silica-glass layer 42. I have. In this embodiment, the mixing step corresponds to a paste making step, and the baking step corresponds to a heat treatment step.

In this case, in this embodiment, the pigment particles 40 are mixed with a raw material of a reaction-curing glass in a state where a silica-glass film (namely, a silica-glass layer 42) is provided on the surface, and Since it is baked on the surface 34 of the glass 32, the silica glass film suppresses the reaction with the glass structure 38 generated from the reaction hardened glass raw material powder during the baking. Therefore, the composition of the glass structure 38 is prevented from being changed, and the reduction in the amount of the pigment particles 40 that can be dissolved in the glass structure 38 and contribute to the emissivity is appropriately suppressed, and high heat resistance is obtained. And a glass film 36 having both high radiation properties.

FIG. 7 is a diagram showing a heat flow in the vicinity of the heat insulating material 30. In the figure, the back surface 44 of the heat insulating material 30 is shown.
A low-temperature argon gas is flowed in a laminar flow state in a gap formed between the surface and the surface 46 of the physiological shielding material 20. The amount of heat qr absorbed by the heat insulating material 30 by the radiation from the cooling material 14 is as follows, assuming that the temperature of the cooling material 14 such as liquid metal sodium, which is high in temperature, approximates an ideal black body and the heat insulating material 30 is an infinite flat plate. 1) [where, .epsilon.n the emissivity of the coolant 14, εg is emissivity of the glass film 36, Tn is the temperature of the coolant 14, Tw ₁ is the temperature of the glass membrane 36 surface, sigma is the Stefan-Boltzmann constant] in expressed. Therefore, the glass film 3
6, the larger the emissivity εg, the larger the amount of heat radiation qg (=
Since the heat absorption qr insulation 30 is reduced σ · εg · Tw ₁ ⁴⁾ and is increased, the surface temperature Tw ₁ is decreased than when there is no glass film 36. On the other hand, the amount of heat transported from the front surface of the heat insulating material 30 to the back surface 44 (that is, the amount of heat transferred by heat conduction) qt is expressed by the following equation (2) (where λc is (The thermal conductivity of the material body 32, Tw ₂ is the temperature of the back surface 44 of the heat insulating material 30, and L is the thickness of the heat insulating material body 32.)
Can be represented by Therefore, the temperature of the surface 46 of the physiological shielding material 20 is maintained at the same value Tm as the conventional one,
Transport heat qt and convection, thermal conduction, and the backside temperature Tw ₂ in a steady state in which the absorption amount of heat from the surface 46 containing the qr matches the case of the conventional similar values, the amount of decrease in the surface temperature Tw ₁ The thickness L can be reduced according to That is, as shown in FIGS. 8 (a) and 8 (b),
Since the temperature gradient within 2 is the same as that of the conventional heat insulating material 26 in which the glass film 36 is not provided, as the emissivity εg increases and the surface temperature Tw ₁ decreases, the similar back surface temperature Tw ₂ is set. Required for the heat insulating material 26 whose surface temperature is Tw ₃ (> Tw ₁ ).
It can be thinner than. qr = σ · (εn · Tn 4 -εg · Tw 1 4) ··· (1) qt = λc · (Tw 1 -Tw 2) / L ··· (2)

The amount of heat transported qt transmitted to the back surface 44 given by the above equation (2) is qct shown by the following equation (3), that is, the amount of heat transmitted from the heat insulating material 30 to the physiological shielding material 20. _{qtr [= αtr (Tw 2 -Tm} )] and is equal to the sum (qtr + qaa) of heat qaa being transported out of the system by the argon gas is flowed between them _{[= αc (Tw 2 -Ta)} ]. Here, in the following equation (3), αtr is the heat transmission coefficient between the back surface 44 of the heat insulating material 30 and the surface 46 of the physiological shielding material 20, αc is the heat transfer coefficient of argon gas, and Ta is the temperature of argon gas. It is. In other words, a part qtr of the transport heat quantity shown in the first term of the following equation (3) is absorbed by the physiological shielding material 20 out of the transport heat quantity qt transmitted to the heat insulating material back surface 44 side. The surface temperature Tm of the physiological shielding material 20 is determined based on the amount of heat absorbed qtr, the amount of heat radiation qac [= αc (Tm−Ta)], and the specific heat. Therefore, the following equation (3) the first term of (qtr) and the second term (qaa), Tm, since both are determined at a temperature Tw ₂ insulation back surface 44 when a constant Ta, the constant insulation material thickness so as to ensure thermal insulation L, defining a Lp, is not to be kept its back side temperature Tw ₂ at a constant value. For example, assuming that the temperature of the argon gas is about Ta = 25 (° C.), the temperature Tm of the surface 46 of the physiological shielding material 20 made of reinforced concrete is 20 to
When the temperature is maintained at about 30 (° C.), the heat transfer coefficient from the coolant 14 to the physiological shielding material 20, that is, the heat transfer coefficient of the entire adiabatic system including laminar flow by argon gas is 40 (W / m ² · K). The thickness L, Lp of the heat insulating material is determined so as to be suppressed to the extent. qct = αtr (Tw ₂ −Tm) + αc (Tw ₂ −Ta) (3)

In short, in this embodiment, the heat insulating material main body 32 and the high-temperature coolant storage portion 24 of the heat insulating material main body 32 are used.
The heat insulating material 30 includes the glass film 36 in which the pigment particles 40 having a high emissivity of about 0.95 and provided on the side surface 34 are dispersed in a glass structure 38. Therefore, the surface 3 of the heat insulating material body 32 on the high-temperature coolant storage portion 24 side is
4, a glass film 36 in which pigment particles 40 are dispersed in a glass structure 38 is provided.
In accordance with the emissivity of the glass film 36 determined according to the emissivity of 0, the heat insulating material 3 on the high-temperature coolant storage portion 24 side.
The surface 34 has high radiant power. Therefore,
The heat transmitted from the high-temperature coolant storage section 24 to the heat insulating material 30 is absorbed by the glass film 36 and efficiently returned to the high-temperature coolant storage section 24 by radiation.
The amount of heat that is absorbed to zero and further released through it outside is reduced. As a result, the heat insulating effect is substantially enhanced, so that the thickness of the heat insulating material 30 required to obtain the same heat insulating effect can be significantly reduced as compared with the related art.

In this embodiment, the glass film 36
Has a silica glass layer 42 provided over the pigment particles 40 at the interface between the pigment particles 40 and the glass structure 38 and containing silicon dioxide at a higher content than the value in the glass structure 38 at the interface. Things. In this way, the glass film 36 provided on the surface 34 of the heat insulating material 30 is provided so as to cover the pigment particles 40 at the interface between the pigment particles 40 and the glass structure 38, and the glass film 38 at the interface is provided. And a silica glass layer 42 containing silicon dioxide with a content higher than the value of Therefore, an interface between the pigment particles 40 and the glass structure 38 is provided with a silica / glass layer 42 having a relatively low reactivity with the pigment particles 40 because the content of silicon dioxide is higher than that of the glass structure 38. Insulation 30
Pigment particles 40 and glass structure 38 during firing for providing a glass film 36 on the surface 34 of the glass and during use of the nuclear reactor.
And the oxidation of the pigment particles 40 are suitably suppressed by the silica glass layer 42 provided at the interface. Accordingly, the original emissivity of the pigment particles 40 is utilized in the glass structure 38 as it is, and the decrease in the emissivity of the pigment particles 40 due to an interfacial reaction or oxidation is suppressed even during use at high temperatures. A higher emissivity is applied and maintained to the film 36 and the heat insulating material 30, and a higher heat insulating effect is obtained and maintained.

In this embodiment, the heat insulating material main body 3
Numeral 2 is composed of silicon nitride / cordierite composite ceramics. In this case, since the heat insulating material main body 32 is made of ceramics, the glass film 36 is provided based on the high heat insulating property of ceramics having a lower thermal conductivity than a metal material such as stainless steel. The heat insulating property of the heat insulating material 30 is further enhanced, and the thickness L required for obtaining a predetermined heat insulating effect can be further reduced.

In this embodiment, the silica glass layer 42 contains 99% by weight or more of silicon dioxide. Therefore, since the content of silicon dioxide is sufficiently high, the interfacial reaction between the pigment particles 40 and the glass structure 38 is further suppressed.

In this embodiment, the silica / glass layer 42 is provided with a thickness of about 100 to several hundreds (nm). By doing so, the thickness of the silica-glass layer 42 is sufficiently large within a range that does not significantly affect the thermal characteristics such as the softening point and the coefficient of thermal expansion of the glass film 36. The interface reaction with the tissue 38 is more reliably suppressed.

Further, according to this embodiment, since the silicon tetraboride used as the pigment particles 40 has an extremely high emissivity of about 0.95, the emissivity of the glass film 36 is increased, and Although the heat insulating property is further enhanced, on the other hand, it has high reactivity with the glass structure 38 due to its non-oxide property. Therefore, silica
The effect of providing the glass layer 42 is more remarkably obtained.

In this embodiment, the pigment particles 40
Has an average particle size of about 40 (μm). Therefore, since the average particle diameter is made sufficiently large, the reactivity with the glass structure 38 is further reduced, and the decrease in the emissivity of the pigment particles 40 is further suppressed. 36, the dispersibility is increased.

In this embodiment, the pigment particles 40
Is contained in the glass film 36 at a ratio of about 2.5 (wt%). Therefore, since the pigment particles 40 are sufficiently contained in the glass film 36, the contribution of the pigment particles 40 to the emissivity of the glass film 36 becomes sufficiently large, and the emissivity of the glass film 36 is sufficiently increased. And the insulation 30
The heat insulating property of the is sufficiently improved.

In this embodiment, the glass film 36
Is provided on the surface 34 of the heat insulating material main body 32 with a thickness of about 0.4 (mm). Therefore, since the glass film 36 is sufficiently thin, the uniformity of the film thickness is improved, and the heat insulating material 30 is formed.
Is provided with a more uniform and higher heat insulating property. That is, since the radiation is mainly generated near the surface (surface layer) of the glass film 36, the glass film 36 does not need to be so thick.

In this embodiment, the glass structure 3
8 is a borosilicate glass containing silicon dioxide as a main component and containing boric acid. In this way, the borosilicate glass has the highest heat resistance and thermal shock resistance among the glasses, and therefore, is required to have higher heat resistance, higher thermal shock resistance, and higher radiation property because it is required to have higher safety. A glass film 36 more suitable as a coating of the heat insulating material 30 is obtained.

In this embodiment, the glass film 36
Is formed at the interface between the glass structure 38 in the glass film 36 and the pigment particles 40.
The pigment coating step of step 1B of providing a silica glass layer 42 of a predetermined thickness containing silicon dioxide with a content higher than the value in 8 on the surface of the pigment particles 40 is performed prior to the mixing step of step 2. . Therefore, in the mixing step, a paste containing the pigment particles 40 provided with the silica-glass layer 42 having a low reactivity with the glass structure 38 and containing the glass powder due to the high content of silicon dioxide is produced. During the heat treatment in the baking step of Step 4, an interface reaction between the glass structure 38 and the pigment particles 40 is suppressed by the silica glass layer 42. Also, during the operation of the nuclear reactor after the glass film 36 is manufactured, the interfacial reaction is similarly suppressed by the silica glass layer 42.

Further, in the present embodiment, the pigment coating step is a step of forming an inorganic polymer film made of an inorganic polymer containing silicon on the surface of the pigment particles 40. And heating the pigment particles 40 on which the inorganic polymer film is formed at a predetermined temperature in an oxidizing atmosphere, so that the silica-glass layer 42 containing silicon dioxide at the predetermined content from the inorganic polymer film.
And a heat treatment step of step B4 for generating In this way, in the polymer film forming step, an inorganic polymer film containing silicon is formed on the surface of the pigment particles 40, and in the heat treatment process, the silica-glass Layer 42 is created. Therefore, since the silica-glass layer 42 is formed on the surface of the pigment particles 40 in the form of an inorganic polymer, a thin film having a uniform thickness can be suitably formed. Therefore, by performing heat treatment in an oxidizing atmosphere, silicon in the inorganic polymer is oxidized, and a silica glass layer 42 containing silicon dioxide at a predetermined content is generated. Therefore, silica glass layer 42 having a predetermined thickness and containing silicon dioxide at a predetermined content can be suitably formed.

In this embodiment, the step of forming the inorganic polymer film is performed by spray-drying a dispersion in which the pigment particles 40 are dispersed in a liquid containing the inorganic polymer. This includes a powder drying step of step B3 of forming a film. By doing so, the inorganic polymer film is formed on the surface of the pigment particles 40 by spray-drying the dispersion containing the inorganic polymer and the pigment particles 40. Therefore, since the liquid containing the inorganic polymer covering the surface of the pigment particles 40 is quickly dried by spray drying to form the inorganic polymer film, the inorganic polymer film having a thinner and uniform thickness is formed. Can be obtained.

In this embodiment, the inorganic polymer is perhydropolysilazane composed of hydrogen (H), nitrogen (N), and silicon (Si). In this way, by firing in an oxidizing atmosphere, silicon and oxygen are combined to form silicon dioxide, and an inorganic polymer film is formed on the surface of the pigment particles 40, while hydrogen and nitrogen are combined. And ammonia (NH ₃ ) is generated and quickly dissipated. Therefore, since the formed inorganic polymer film, and hence the silica-glass layer 42 formed therefrom, contains silicon dioxide at a very high content, the interface reaction between the pigment particles 40 and the glass structure 38 is further reduced. Is suppressed.

Further, in this embodiment, the baking step of the step 4 is heating in a non-oxidizing atmosphere.
In this case, since oxygen does not exist in the firing atmosphere, the oxidation of the pigment particles 40 during the firing of the glass film 36 is further suppressed.

While the embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be embodied in still another embodiment.

For example, in the embodiment, the heat insulating material main body 3
Although the silicon nitride / cordierite composite ceramics was used as a material for forming the material 2, the constituent materials and the thickness of the material depend on the temperature of the coolant 14 in the high-temperature coolant storage portion 24 of the reactor vessel 10, Material 14 and physiological shielding material 2
0 is appropriately changed depending on the type of 0, for example, silicon nitride,
Other ceramic materials having relatively high strength and low thermal conductivity, such as silicon carbide and mullite, may be used alone or as a composite material, or in combination with a heat-resistant and corrosion-resistant steel alloy or a nickel-based heat-resistant alloy. Further, instead of the flat heat-insulating material body 32 shown in the embodiment, a honeycomb structure or a heat-insulating material body having a lotus root-like hole may be used. The heat insulating material main body having these structures can be formed by, for example, injection molding, casting, or the like, but is more advantageous in terms of heat insulation than a monolithic structure.

In the embodiment, the glass structure 38
A glass frit comprising high silica / glass frit with boron oxide was used as the glass frit, but a glass frit containing boron oxide may be used from the beginning, and a glass frit containing no boron oxide is used as it is. May be used. The composition of the glass used is appropriately changed according to the use environment such as the temperature and the type of the coolant 14 in the high-temperature coolant storage unit 24. Further, high silica glass such as quartz glass may be used instead of the reaction hardened glass.

In the embodiment, silicon tetraboride having an average particle size of about 40 (μm) is used as the pigment particles 40, but the type of the pigment particles 40 satisfies the required thickness of the heat insulating material 30. In consideration of the emissivity required for this purpose and the heat resistance of the pigment particles 40 themselves, other silicon borides such as silicon hexaboride (SiB ₆ ), alumina (Al ₃ O ₃ ), manganese dioxide (MnO ₂ ) ,
Chromium oxide (Cr ₂ O _3), iron oxide (Fe ₂ O _3), mullite _{(3Al 2 O 3 · 2SiO 2} ), cordierite (2MgO · 2Al ₂ O ₃
・ 5SiO ₂ ), clay, aluminum titanate (AlTiO ₃ ),
One to several kinds of various materials having relatively high total emissivity such as silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), marble, limestone, mica, glass, white ceramics, brick (red), asbestos, etc. It is appropriately selected and used. Further, the average particle size of the pigment particles 40 is appropriately set in a range where good dispersibility can be obtained. The pigment particles do not necessarily have to be substantially spherical, and may be, for example, pellets or short fibers, and the same effect can be obtained regardless of the shape.

In the embodiment, perhydropolysilazane was used as the inorganic polymer for forming the silica-glass layer 42 on the surface of the pigment particles (silicon tetraboride powder) 40. Other inorganic polymers may be used as long as they contain silicon capable of forming the silica-glass layer 42 by heating or the like as shown in the heat treatment step.

In the embodiment, the amount of boron oxide added to the glass frit is about 8 (wt%). However, the amount of the addition depends on the heat resistance and strength of the glass structure 38 and the glass frit. It is appropriately set in consideration of the composition and the like. For example, the glass frit containing no boron oxide is appropriately changed in the range of about 8 to 13 (wt%).

In the embodiment, the baking step is performed by slow heating in a nitrogen atmosphere. However, the atmosphere may be appropriately changed according to the type of the pigment particles 40, and may be reduced, vacuum, or reduced. In the case where is an oxide, the atmosphere may be an oxidizing atmosphere. Further, when the pigment particles 40 are covered with silica glass as in the embodiment, oxidation and reaction with the glass structure 38 are unlikely to occur. Can be baked. As the non-oxidizing atmosphere, an inert gas atmosphere such as argon may be used instead of the nitrogen atmosphere, and baking may be performed under vacuum. The baking atmosphere is determined solely by the material of the heat insulating body 32.

In the embodiment, the silica / glass layer 42 is provided on the surface of the pigment particles 40. However, if the decrease in the emissivity during baking and use is not a serious problem, the silica / glass layer may be used. 42 may not be provided.

Various numerical values that determine the composition and physical properties of the glass film 36, such as the mixing ratio of the reaction hardening glass raw material powder and the pigment particles 40, depend on the heat insulating properties required of the heat insulating material 30. It is set appropriately.

In the embodiment, the glass film 36 is
Although the film thickness is provided at about 0.4 (mm), the thickness is appropriately changed depending on the use conditions and the like. However, if the thickness is too large, it becomes difficult to form a film with a uniform thickness, and the glass film 36 is liable to be damaged due to expansion during baking. Therefore, the thickness is desirably 1 (mm) or less.

In the embodiment, the case where the present invention is applied to the heat insulating material 30 provided between the high temperature coolant storage part 24 and the physiological shielding material 20 of the fast breeder reactor has been described. The present invention is similarly applied to a heat insulating material provided in another part such as between the storage part 24 and the low-temperature coolant storage part 22, and further includes a gas cooling furnace such as a carbon dioxide cooling furnace and a high temperature gas cooling furnace, and a pressurized water light water reactor. The present invention can be similarly applied to other types of nuclear reactors such as a light water reactor such as a water reactor and a boiling water reactor, or a heavy water reactor.

In the embodiment, the heat insulating material main body 32 is used.
Ion-exchanged water and P
Although the coating slurry was prepared using the VA aqueous solution, ethanol or isopropyl alcohol may be used instead of water as a solvent for preparing the slurry, and methylcellulose or PVA may be used as the organic binder instead of PVA. Ethyl cellulose or the like may be used. Further, for mixing the slurry, an attritor may be used instead of the porcelain pot (ie, ball mill). As a method for applying the coating slurry, dipping may be used instead of spray application.

Although not specifically exemplified, the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a configuration of a main part of a fast breeder reactor.

FIG. 2 is a diagram illustrating a cross-sectional structure of a heat insulating material used in the fast breeder reactor of FIG.

FIG. 3 is a process chart illustrating a method for forming the glass film of FIG. 2;

FIG. 4 is a process diagram illustrating an RCG manufacturing process in the process diagram of FIG. 3;

FIG. 5 is a process diagram illustrating a pigment coating process in the process diagram of FIG. 3;

FIG. 6 is a diagram illustrating a structure of an inorganic polymer.

FIG. 7 is a diagram illustrating a heat flow near a heat insulating material.

FIGS. 8 (a) and (b) are diagrams for explaining the temperature gradient in the thickness direction of the heat insulating material of the present invention and the conventional heat insulating material, respectively.

[Explanation of symbols]

 10: Reactor Vessel 12: Reactor 14: Coolant 22: Low Temperature Coolant Reservoir 24: High Temperature Coolant Reservoir 30: Insulation Material for Reactor 32: Insulation Material Body 36: Glass Film 38: Glass Structure 40: Pigment Particle 42: silica glass layer (pigment coating layer)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Kato 1-336 Noritakeshinmachi, Nishi-ku, Nagoya City, Aichi Prefecture Inside Noritake Company Limited (72) Inventor Kenji Yano 3-chome Noritake Shinmachi, Nishi-ku, Nagoya City, Aichi No. 1-36 Noritake Company Limited Limited (72) Inventor Yoshiki Kato 1-336 Noritake Shinmachi, Nishi-ku, Nagoya City, Aichi Prefecture 1-32 Noritake Company Limited Limited (72) Inventor Takamitsu Fukui Noritake Nishi-ku, Nagoya City, Aichi Prefecture No. 1-36, Machi Noritake Co., Ltd. (72) Inventor Takamitsu Isoya 3-36, Noritakeshinmachi, Nishi-ku, Nagoya, Aichi Prefecture Within Noritake Co., Ltd. (72) Inventor Masakazu Hiyoshi Nagoya, Aichi Prefecture 1-3-3 Noritakeshinmachi, Nishi-ku No. 6 Noritake Co., Ltd. (72) Inventor Hirokazu Matsunaga 3-36 Noritake Shinmachi, Nishi-ku, Nagoya-shi, Aichi Noritake Co., Ltd.

Claims (3)

[Claims] 1. A coolant based on a nuclear reaction in a reactor core in a process of sequentially flowing the coolant through a low-temperature coolant storage part, a core, and a high-temperature coolant storage part provided in a nuclear reactor vessel. In a reactor of the type in which is heated to a high temperature, in order to suppress heat transfer from the high-temperature coolant storage portion in which the coolant heated to high temperature is stored to the periphery thereof, the coolant is provided outside the high-temperature coolant storage portion. A heat insulating material for a nuclear reactor provided, comprising: a heat insulating material body having a predetermined thickness; and pigment particles having a predetermined emissivity provided on a surface of the heat insulating material body on a side of the high-temperature coolant storage portion, in a glass structure. A heat insulating material for a nuclear reactor, comprising: a glass film dispersed in a reactor. 2. The glass film is provided so as to cover the pigment particles at an interface between the pigment particles and the glass structure, and has a higher content of silicon dioxide (SiO ₂ ) than the value in the glass structure at the interface. 2. The heat insulating material for a nuclear reactor according to claim 1, wherein the heat insulating material has a pigment coating layer having a predetermined thickness. 3. The heat insulating material for a nuclear reactor according to claim 1, wherein said heat insulating material main body is made of ceramics.