WO2014097740A1 - 原子炉用部材 - Google Patents
原子炉用部材 Download PDFInfo
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- WO2014097740A1 WO2014097740A1 PCT/JP2013/078947 JP2013078947W WO2014097740A1 WO 2014097740 A1 WO2014097740 A1 WO 2014097740A1 JP 2013078947 W JP2013078947 W JP 2013078947W WO 2014097740 A1 WO2014097740 A1 WO 2014097740A1
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- graphite
- coating layer
- nuclear
- aggregate
- particulate matter
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C5/00—Moderator or core structure; Selection of materials for use as moderator
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C5/00—Moderator or core structure; Selection of materials for use as moderator
- G21C5/12—Moderator or core structure; Selection of materials for use as moderator characterised by composition, e.g. the moderator containing additional substances which ensure improved heat resistance of the moderator
- G21C5/126—Carbonic moderators
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C11/00—Shielding structurally associated with the reactor
- G21C11/02—Biological shielding ; Neutron or gamma shielding
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C11/00—Shielding structurally associated with the reactor
- G21C11/02—Biological shielding ; Neutron or gamma shielding
- G21C11/028—Biological shielding ; Neutron or gamma shielding characterised by the form or by the material
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F1/00—Shielding characterised by the composition of the materials
- G21F1/12—Laminated shielding materials
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F3/00—Shielding characterised by its physical form, e.g. granules, or shape of the material
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Definitions
- the present invention relates to a reactor for a reactor such as a light water reactor such as a boiling water type or a pressurized water type, a heavy water reactor, a gas cooling reactor such as a high temperature gas reactor, an ultra high temperature gas reactor, a molten metal cooling reactor, or a fast breeder reactor.
- a reactor for a reactor such as a light water reactor such as a boiling water type or a pressurized water type, a heavy water reactor, a gas cooling reactor such as a high temperature gas reactor, an ultra high temperature gas reactor, a molten metal cooling reactor, or a fast breeder reactor.
- the present invention relates to a deceleration member and a shield.
- Graphite materials are not only widely used as moderators for nuclear reactors but also as shields because they absorb less neutrons and have a relatively large neutron moderator.
- Graphite moderators are used not only in graphite moderation reactors but also in high-temperature gas reactors where research and development are underway.
- graphite material shields are used in fields such as fast reactors.
- Patent Document 1 describes a method of operating a nuclear reactor for suppressing the occurrence of creep deformation. Specifically, by changing the operation mode of the reactor, the temperature of the graphite structure in the reactor is changed, so that the opposite compressive stress is generated in the portion where the tensile stress is generated, and the compressive stress is generated. It describes a method of extending the life of the graphite structure by reducing the residual stress generated in the graphite structure by generating the opposite tensile stress in the part where it is reversed and thereby causing the reverse creep deformation. .
- the above-described method is not a method for suppressing creep deformation of the graphite structure (graphite material) itself, but a method for extending the life of the graphite structure by an operation method. Not only can the reactor capacity be fully demonstrated, but it is preferable to operate while changing the reactor power frequently in order to maintain the stability of the reactor. is not.
- the present invention instead of improving the operating conditions and equipment of the nuclear reactor, it is possible to use the existing graphite material and to use it stably without any swelling or creep deformation even when directly exposed to neutrons.
- the purpose is to provide.
- the nuclear member of the present invention for solving the above problems is (1) It consists of a core part made of an aggregate of graphite particulate matter and a coating layer made of a ceramic dense body covering the core part. Furthermore, the following aspects are preferable. (2) The particulate substances are not bonded to each other. (3) The particulate matter is made of natural graphite or artificial graphite. (4) The coating layer is a vapor deposition layer. (5) The coating layer is composed of one or more coating layers selected from pyrolytic carbon, silicon carbide, zirconium carbide, and tantalum carbide. (6) A neutron moderating member and a shield using the nuclear reactor member described above.
- the nuclear reactor member of the present invention comprises a core part made of an aggregate of graphite particulate matter and a coating layer made of a ceramic dense body covering the core part. Since graphite affected by neutron irradiation is used in the form of aggregates of particulate matter, the particulate matter is not bonded to each other, and even if creep phenomenon, expansion, contraction, etc. occur, It does not affect the shape and dimensions.
- the aggregate of the graphite particulate material is not particularly limited, so that a general-purpose graphite material already having swaging and creep deformation data during neutron irradiation can be used. Therefore, it is not necessary to newly collect these data, and it can be adopted as a member for nuclear power without taking time and effort.
- the nuclear reactor member of the present invention has a coating layer made of a dense ceramic body covering the core portion. Since the coating layer made of a dense body is more durable than neutron irradiation than graphite, it has less influence on the shape and dimensions of the nuclear reactor member. For this reason, according to the nuclear reactor member of the present invention, it is possible to provide a nuclear reactor component that can be used stably without being subjected to creep deformation even when directly exposed to neutrons.
- the nuclear reactor member of the present invention is characterized by comprising a core portion made of an aggregate of graphite particulate matter and a coating layer made of a ceramic dense body covering the core portion.
- the graphite of the nuclear reactor member of the present invention may be any material and is not particularly limited. For example, natural graphite, artificial graphite, quiche graphite, or the like may be used.
- a general-purpose graphite material having a database of swelling and creep deformation by neutron irradiation can be used, it can be easily adopted as a nuclear reactor member.
- a general-purpose graphite material having a database of swelling and creep deformation includes, for example, ET-10 manufactured by Ibiden Co., Ltd. Not.
- the core part of the present invention comprises an aggregate of graphite particulate materials. Since it consists of an aggregate of graphite particulate matter, even if individual particulate matter creeps or deforms, it does not affect the coating layer that maintains the overall shape. It is possible to provide a nuclear reactor member that can be used stably without ring or creep deformation. Moreover, when using as a member for neutron moderation, it is preferable to use a high-purity material for the aggregate of graphite particulate substances.
- the desirable ash content of the aggregate of graphite particulate materials is 20 ppm by weight or less. If it exceeds 20 ppm by weight, the impurities absorb neutrons, making it difficult to increase the reactor power.
- the desirable boron content of the aggregate of graphite particulate materials is 1.0 ppm by weight or less. Since boron easily absorbs neutrons, if it exceeds 1.0% by weight and boron is contained, it is difficult to increase the output of the nuclear reactor.
- a powder or particle of boron, B 4 C or the like is used in the form of graphite particulate matter. It may be added to the aggregate.
- the particulate matter includes powders, granules and a mixture thereof.
- the particle diameter of the graphite particulate material is not particularly limited.
- powders or granules having a 50% volume particle diameter of 0.1 ⁇ m to 1 mm can be used.
- the aggregate of the particulate matter may be used by blending powders or granules having different particle size distributions. When powders or granules having different particle size distributions are mixed and used, fine particles are inserted into the gaps between coarse particles, and the bulk density of the aggregate of the particulate substances can be increased.
- a desirable apparent density of the aggregate of graphite particulate materials is 1.0 to 2.0 g ⁇ cm ⁇ 3 .
- the apparent density is less than 1.0 g ⁇ cm ⁇ 3 , the voids increase and the ability to decelerate neutrons decreases.
- the apparent density exceeds 2.0 g ⁇ cm ⁇ 3 , the process of film formation by vapor deposition causes a springback phenomenon in which the surface of the aggregate of the particulate matter solidified by the ingress of CVD gas expands. Since a force is applied to the thin coating layer in the middle of the film and the coating layer is easily broken, it becomes difficult to obtain a nuclear member having a desired shape.
- the 50% volume particle diameter of the aggregate of graphite particulate materials can be measured with a laser diffraction particle size distribution meter.
- region exceeding 2 mm is measured using the test sieve auxiliary.
- the apparent density of the aggregate of graphite particulate materials is a density measured while including voids between the aggregates of graphite particulate materials. If the shape of the nuclear reactor component is complex and it is difficult to measure the apparent density, measure the volume and mass of the nuclear reactor component, then destroy it, remove the core, and measure the volume and mass again. To do.
- the mass of the core part can be obtained by calculating each difference.
- the volume of the whole nuclear reactor member and the core part can be easily measured even in an irregular shape by measuring by the water replacement method.
- the coating layer made of a ceramic dense body covering the core portion there is no particular limitation on the coating layer made of a ceramic dense body covering the core portion.
- a sintered body is formed in a shell shape, and an internal space filled with an aggregate of graphite particulate matter, or an aggregate of graphite particulate matter is press-molded to obtain the desired shape, and then the surface
- methods such as vapor-depositing a hard ceramic film.
- Methods such as chemical vapor deposition (CVD) and physical vapor deposition (PVD) can be used as the ceramic film deposition method.
- CVD chemical vapor deposition
- PVD physical vapor deposition
- chemical vapor deposition obtains a ceramic by thermally decomposing a raw material gas, so that a coating layer made of a dense body of the nuclear reactor member of the present invention can be easily obtained.
- the coating layer made of a ceramic dense body covering the core portion covers the entire core portion. This is because if the entire core portion is covered, the aggregate of graphite particulate matter is unlikely to flow out of the nuclear member.
- methods such as thermal CVD, photo CVD, laser CVD, and plasma CVD can be used.
- the aggregate of graphite particulate substances can be given a certain shape by pressing. Any pressing method such as CIP (Cold Isostatic Press), HIP (Hot Isostatic Press), and uniaxial press can be used. Further, a thin binder may be added to the graphite particulate material so that the shape can be maintained until a coating layer is formed.
- an organic binder As the binder, an organic binder, an inorganic binder, or the like can be used and is not particularly limited. However, it is preferable to use an organic binder. If it is an organic binder, it is carbonized by heating or is pyrolyzed and volatilized. When the organic binder is carbonized, it becomes carbon and remains in the core part. When the organic binder is thermally decomposed and completely volatilized, nothing remains in the core part. A core part can be formed only with an aggregate.
- the core portion may be wet-molded by adding a solvent to the graphite particulate material.
- a solvent for example, alcohol can be added to graphite particulate matter to make a cake, and after imparting the desired shape by press molding, the core can be obtained.
- a slurry obtained by adding alcohol to graphite particulate material is poured into a mold having a net-like surface to remove the solvent, and then dried to obtain a core part.
- graphite is pulverized finely, it becomes difficult to increase the bulk density by entraining air, so it is necessary to press it with high pressure. , Fine particles are easily filled in the gaps between the large particles. For this reason, it becomes easy to raise bulk density and a high-density core part can be obtained easily.
- the material of the coating layer of the present invention is not particularly limited.
- Examples thereof include carbide ceramics, oxide ceramics, nitride ceramics, and carbonaceous materials.
- Examples thereof include pyrolytic carbon, silicon carbide, zirconium carbide, tantalum carbide, titanium carbide and the like.
- silicon carbide, zirconium carbide, tantalum carbide, and titanium carbide have corrosion resistance to oxygen and water, so that they are less susceptible to consumption due to water and oxygen present in the reactor even when used for a long time. Available.
- these coating layers are more resistant to neutron irradiation than graphite, so that the influence on the shape and dimensions of the reactor member can be reduced.
- the coating layer may be a single layer or may be composed of a plurality of layers.
- different types of coating layers or the same type of coating layer may be used, and in the case of a compound such as carbide or nitride, the element ratio may be different.
- a combination of Ta 4 C 3 , Ta 2 C, and TaC can be used.
- the thickness of a coating layer is not specifically limited, It is desirable that they are 10 micrometers or more and 5 mm or less. If the thickness of the coating layer is 10 ⁇ m or more, it is difficult for the coating layer to be punctured due to wear, impact, or the like, and the internal graphite particulate matter can be prevented from flowing out to the outside. When the thickness of the coating layer is 5 mm or less, variations in thickness due to the difference in film formation rate hardly occur, and a nuclear reactor member with high dimensional accuracy can be obtained. A more desirable coating layer thickness is 20 ⁇ m to 3 mm. If the thickness of the coating layer is 20 ⁇ m or more, the coating layer has high mechanical strength, so that it can be made difficult to break in the nuclear reactor.
- the measuring method of the thickness of a coating layer cuts the member for nuclear power, and exposes the cross section of a coating layer.
- the cross section can be obtained by measuring with a SEM (scanning electron microscope), a tool microscope or the like.
- the coated graphite molded body can be made uniform by uniformly dispersing the graphite powder inside using an ultrasonic device.
- the shape, size, and application of the nuclear reactor member are not particularly limited. Since it has graphite inside, it has a large ability to decelerate neutrons, and is particularly useful as a member for decelerating neutrons.
- a moderator a graphite furnace, a high temperature gas furnace, etc. can use suitably. In addition, it can be used as a shield to prevent radiation from leaking.
- the shape of the neutron moderator member is not particularly limited.
- a spherical neutron moderating member having a diameter of 30 to 100 mm can be suitably used in a high temperature gas furnace, and a neutron moderating member having a hexagonal column shape having a height of 80 cm and a hexagonal bottom surface having a side of 20 cm can be suitably used.
- the neutron moderating member can be used by appropriately changing the shape and size according to the structure and use conditions of the furnace.
- Example 1 according to the present invention will be described below. It is sectional drawing of the member for nuclear power of Example 1 of this invention.
- Example 1 has a structure in which the surface of a pellet-shaped core part is covered with a silicon carbide (SiC) coating layer.
- SiC silicon carbide
- ⁇ Coating material forming step> The core part obtained in the above process was placed in a CVD furnace with care so as not to collapse, and an SiC layer was formed by a thermal CVD method. Specifically, the core obtained in the above step is placed in a normal pressure CVD furnace and heated to 1200 ° C., and then a mixed gas using methyltrichlorosilane as a source gas and hydrogen as a carrier gas is introduced. After continuing the time vapor deposition, the mixed gas and the heating were stopped and cooled to form a SiC coating layer on the surface of the core portion. The thickness of the formed SiC layer was 40 ⁇ m.
- Example 2 according to the present invention will be described below. It is sectional drawing of the member for nuclear power of Example 2 of this invention.
- Example 2 has a structure in which the surface of the pellet-shaped core portion is covered with a pyrolytic carbon coating layer and further covered with a silicon carbide (SiC) coating layer.
- SiC silicon carbide
- a graphite powder (3.1 g), which is an aggregate of graphite particulate matter having a 50% volume particle diameter of 3.65 ⁇ m, was filled in a mold having an opening of ⁇ 25 mm and pressurized at 19 MPa.
- the core part in which the graphite powder was molded was taken out from the mold.
- the graphite powder was obtained by roughly pulverizing isotropic graphite material ET-10 manufactured by Ibiden Co., Ltd. and then pulverizing it with a jet mill.
- the bulk density of the core portion was 1.05 g ⁇ cm ⁇ 3 .
- a pyrolytic carbon layer was first formed, and then a SiC layer was formed.
- the core part obtained in the above step was placed in a CVD furnace with care so as not to collapse, and a pyrolytic carbon layer was formed by a thermal CVD method.
- the core obtained in the above step is placed in a CVD furnace and heated to 1500 ° C., then methane is introduced as a raw material, and vapor deposition is continued for 5 hours, and then the source gas and heating are stopped.
- a coating layer of pyrolytic carbon was formed on the surface of the core portion.
- the thickness of the formed SiC layer was 40 ⁇ m.
- the core part covered with pyrolytic carbon was put in another CVD furnace, and a SiC layer was formed by a thermal CVD method.
- the core obtained in the above step is placed in a normal pressure CVD furnace and heated to 1200 ° C., and then a mixed gas using methyltrichlorosilane as a source gas and hydrogen as a carrier gas is introduced. After continuing the time vapor deposition, the mixed gas and the heating were stopped and cooled to form a SiC coating layer on the surface of the core portion.
- the thickness of the formed SiC layer was 40 ⁇ m.
- the coating layers (pyrolytic carbon layer and SiC layer) of the obtained nuclear reactor member are destroyed and the inside is confirmed, the aggregate of graphite particulate matter is powdery or granular without being bonded and integrated. Was maintained. For this reason, even if the aggregate of graphite particulate matter is irradiated with neutrons and expanded and contracted, the overall shape is maintained by the coating layer, and the powdery or granular core part does not damage the reactor member.
- a nuclear reactor member that can be used stably without being subjected to creep deformation even when directly exposed to neutrons can be obtained.
- the nuclear member obtained in this example is in the form of pellets, but the shape of the nuclear member can be changed as appropriate depending on the shape and type of the nuclear reactor.
- a dilute binder can be added to the aggregate of graphite particulate matter, and the shape can be maintained until vapor phase deposition is started. Can also respond.
Abstract
Description
黒鉛材料の減速材は、黒鉛減速原子炉の他、研究開発が進められている高温ガス炉などで使用されている。さらに、黒鉛材料の遮蔽体は高速炉などの分野で使われている。
原子炉の運転方法を制約するので、原子炉の能力を十分に発揮できないばかりでなく、頻繁に原子炉の出力を変えながら運転することは、原子炉の安定性を維持する上では、好ましいことではない。
(1)黒鉛の粒子状物質の集合体からなるコア部と、コア部を覆うセラミックの緻密体からなる被覆層とからなる。
さらに以下の態様が好ましい。
(2)前記粒子状物質は、互いに結合していない。
(3)前記粒子状物質は、天然黒鉛または、人造黒鉛からなる。
(4)前記被覆層は、気相蒸着層である。
(5)前記被覆層は、熱分解炭素、炭化珪素、炭化ジルコニウム、炭化タンタルから選ばれる1または2以上の被覆層からなる。
(6)前記記載の原子炉用部材を用いた中性子減速用部材及び遮蔽体。
本発明の原子炉用部材の黒鉛とは、どのようなものでもよく特に限定されない。例えば、天然黒鉛、人造黒鉛、キッシュ黒鉛などどのようなものでも良い。特に、既に中性子線照射によるスウェリング、クリープ変形のデータベースを有する汎用の黒鉛材料を使用できるので、原子炉用部材として容易に採用することができる。スウェリング、クリープ変形のデータベースを有する汎用の黒鉛材料としては、例えばイビデン(株)製ET-10などがあるが、スウェリング、クリープ変形のデータベースを有していれば、特にメーカー、グレードは限定されない。
本発明のコア部は、黒鉛の粒子状物質の集合体からなる。黒鉛の粒子状物質の集合体からなるので、個々の粒子状物質がクリープあるいは変形しても全体の形状を維持する被覆層に影響を与えることがないので、中性子に直接曝されても、スウェリング、クリープ変形なく安定して使用できる原子炉用部材を提供することができる。
また、中性子減速用部材として使用する場合、黒鉛の粒子状物質の集合体は、高純度の材料を用いることが好ましい。黒鉛の粒子状物質の集合体の望ましい灰分含有量は、20重量ppm以下である。20重量ppmを超えると、不純物が中性子を吸収し、原子炉の出力を上げにくくなる。さらに、黒鉛の粒子状物質の集合体の望ましいホウ素含有量は、1.0重量ppm以下である。ホウ素は中性子を吸収し易いので、1.0重量%を超えてホウ素を含有すると、特に原子炉の出力を上げにくくなる。
なお、本発明の原子力用部材を制御部材(例えば、制御棒、緊急時遮蔽材)として使用する場合には、ホウ素、B4C等の粉体あるいは粒体を形態で黒鉛の粒子状物質の集合体に添加しても良い。
黒鉛の粒子状物質の集合体の見かけ密度とは、黒鉛の粒子状物質の集合体間の空隙を含んだまま測定した密度である。原子炉用部材の形状が複雑な形状であり、見かけ密度の測定が困難な場合は、原子炉用部材の体積、質量を測定した後に、破壊してコア部を除去し再度体積、質量を測定する。コア部の質量はそれぞれの差を算出することによって得ることができる。原子炉用部材全体及びコア部の体積は、水置換法により測定することにより、不定形な形状でも容易に測定することができる。
コア部を覆うセラミックの緻密体からなる被覆層は、コア部全体を覆っていることが好ましい。コア部全体を覆っていると、黒鉛の粒子状物質の集合体が原子力部材の外部に流出しにくいからである。
化学気相成長としては、熱CVD、光CVD、レーザーCVD、プラズマCVDなどの方法が利用できる。黒鉛の粒子状物質の集合体は、プレスすることにより、一定の形状を付与することができる。プレスの方法は、CIP(Cold Isostatic Press)、HIP(Hot Isostatic Press)、一軸プレスなどどのようなものでも利用することができる。
さらに黒鉛の粒子状物質に希薄なバインダを加え、被覆層が形成されるまで形状を維持できるようにしても良い。バインダとしては、有機バインダ、無機バインダなどが利用でき特に限定されないが、有機バインダを用いることが好ましい。有機バインダであれば、加熱することによって炭化するかあるいは熱分解し揮散する。
有機バインダが炭化した場合には、炭素となってコア部に残留し、有機バインダが熱分解し完全に揮散した場合にはコア部には何も残ることなく、使用した黒鉛の粒子状物質の集合体のみでコア部を形成することができる。
黒鉛は、細かく粉砕すると空気を巻き込んでかさ密度を高めにくくなるので、高い圧力をかけてプレスする必要があるが、湿式でコア部を形成した場合、流体の作用で黒鉛の粒子が移動しやすくなり、大きな粒子の隙間に細かな粒子が充填されやすくなる。このためかさ密度を高めやすくなり、高密度のコア部を容易に得ることができる。
被覆層は、単層であっても良いが、複数層で構成されていても良い。複数層で構成する場合は、異なる種類の被覆層であっても同一の種類の被覆層でも良く、炭化物、窒化物などの化合物である場合には、その元素比が異なっていても良い。たとえば、炭化タンタルの場合Ta4C3、Ta2C、TaCの組み合わせなどが挙げられる。
さらに望ましい被覆層の厚さは、20μm~3mmである。被覆層の厚さが20μm以上であれば、被覆層が高い機械的強度を有しているので、原子炉内で破損しにくくすることができる。被覆層の厚さが3mm以下であれば、成膜速度の差による厚みのバラツキの影響を小さくすることができる。
被覆層の厚さの測定方法は、原子力用部材を切断し、被覆層の断面を露出させる。断面をSEM(走査電子顕微鏡)、工具顕微鏡などで測定することによって得ることができる。
被覆された黒鉛成型体は超音波装置を用いて内部の黒鉛粉を均等に分散させ、均一性を図ることができる。
以下に本発明に係る実施例1について説明する。本発明の実施例1の原子力用部材の断面図である。実施例1は、ペレット状のコア部の表面が炭化珪素(SiC)の被覆層で覆われた構造である。
50%体積粒子径が3.65μmの黒鉛の粒子状物質である黒鉛粉3.1gをφ25mmの開口を有する金型に充填し、19MPaで加圧した。金型から、黒鉛粉が成形されたコア部を取り出した。φ25×6mmの脆く崩れやすい平板状のコア部が形成された。
黒鉛粉は、イビデン(株)製等方性黒鉛材ET-10を粗粉砕後、ジェットミルによって粉砕することによって得た。
コア部のかさ密度は、1.05g・cm‐3であった。
前記工程で得られたコア部を崩れないように注意しながらCVD炉の中に入れ、熱CVD法でSiC層を形成した。具体的には、常圧のCVD炉中に前記工程で得られたコア部を入れ、1200℃に加熱した後、メチルトリクロロシランを原料ガス、水素をキャリアガスとした混合ガスを導入し、5時間気相蒸着を継続した後、混合ガス及び加熱を止め冷却することによりコア部の表面に、SiCの被覆層を形成させた。
形成されたSiC層の厚さは、40μmであった。
得られた原子炉用部材のSiC層を破壊し、内部を確認すると、黒鉛の粒子状物質の集合体は、結合して一体化することなく、粉状あるいは粒状を維持していた。このため、黒鉛の粒子状物質の集合体に中性子が照射され膨張、収縮しても、全体形状は被覆層によって維持され、粉状あるいは粒状のコア部が原子炉用部材を破損させることがなく、中性子に直接曝されても、スウェリング、クリープ変形などすることなく安定して使用できる原子炉用部材を得ることができる。
以下に本発明に係る実施例2について説明する。本発明の実施例2の原子力用部材の断面図である。実施例2は、ペレット状のコア部の表面が熱分解炭素の被覆層で覆われ、さらに炭化珪素(SiC)の被覆層で覆われた構造である。
50%体積粒子径が3.65μmの黒鉛の粒子状物質の集合体である黒鉛粉3.1gをφ25mmの開口を有する金型に充填し、19MPaで加圧した。金型から、黒鉛粉が成形されたコア部を取り出した。φ25×6mmの脆く崩れやすい平板状のコア部が形成された。
黒鉛粉は、イビデン(株)製等方性黒鉛材ET-10を粗粉砕後、ジェットミルによって粉砕することによって得た。
コア部のかさ密度は、1.05g・cm‐3であった。
本実施例では、実施例1とは異なり、まず熱分解炭素層を形成し、その後SiC層を形成した。
前記工程で得られたコア部を崩れないように注意しながらCVD炉の中に入れ、熱CVD法で熱分解炭素層を形成した。具体的には、CVD炉中に前記工程で得られたコア部を入れ、1500℃に加熱した後、メタンを原材料として導入し、5時間気相蒸着を継続した後、原料ガス及び加熱を止め冷却することによりコア部の表面に、熱分解炭素の被覆層を形成させた。
形成されたSiC層の厚さは、40μmであった。
形成されたSiC層の厚さは、40μmであった。
2、21、22 被覆層
10 原子力用部材
Claims (6)
- 黒鉛の粒子状物質の集合体からなるコア部と、コア部を覆うセラミックの緻密体からなる被覆層と、からなることを特徴とする原子炉用部材。
- 前記粒子状物質は、互いに結合していないことを特徴とする請求項1に記載の原子力用部材。
- 前記粒子状物質は、天然黒鉛または、人造黒鉛からなることを特徴とする請求項1又は請求項2に記載の原子力用部材。
- 前記被覆層は、気相蒸着層であることを特徴とする請求項1~3のいずれか一項に記載の原子炉用部材。
- 前記被覆層は、熱分解炭素、炭化珪素、炭化ジルコニウム、炭化タンタル、炭化チタンから選ばれる1または2以上の被覆層からなることを特徴とする請求項1~4のいずれか一項に記載の原子炉用部材。
- 請求項1~5のいずれか一項に記載の原子炉用部材を用いた中性子減速用部材及び遮蔽体。
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PL13865341T PL2937866T3 (pl) | 2012-12-19 | 2013-10-25 | Element do reaktorów jądrowych |
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JP6473602B2 (ja) * | 2014-11-12 | 2019-02-20 | イビデン株式会社 | 黒鉛ブロック |
JP6473601B2 (ja) * | 2014-11-12 | 2019-02-20 | イビデン株式会社 | 炉心構造材 |
JP6415966B2 (ja) * | 2014-12-22 | 2018-10-31 | イビデン株式会社 | 原子炉構造物 |
JP6473616B2 (ja) * | 2014-12-22 | 2019-02-20 | イビデン株式会社 | 原子炉構造物の製造方法 |
JP6473617B2 (ja) * | 2014-12-22 | 2019-02-20 | イビデン株式会社 | 原子炉構造物 |
WO2019037624A1 (zh) * | 2017-08-24 | 2019-02-28 | 南京中硼联康医疗科技有限公司 | 中子捕获治疗系统 |
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JP2001194481A (ja) | 2000-01-17 | 2001-07-19 | Japan Atom Energy Res Inst | 原子炉用黒鉛構造物の長寿命化の方法 |
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US20150332792A1 (en) | 2015-11-19 |
KR20150086501A (ko) | 2015-07-28 |
JP6081182B2 (ja) | 2017-02-15 |
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