JP6296874B2 - Reactor control rod - Google Patents

Reactor control rod Download PDF

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JP6296874B2
JP6296874B2 JP2014087021A JP2014087021A JP6296874B2 JP 6296874 B2 JP6296874 B2 JP 6296874B2 JP 2014087021 A JP2014087021 A JP 2014087021A JP 2014087021 A JP2014087021 A JP 2014087021A JP 6296874 B2 JP6296874 B2 JP 6296874B2
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eutectic
control rod
neutron
storage
oxide
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研一 吉岡
研一 吉岡
浩志 松宮
浩志 松宮
菊池　司
司 菊池
智子 田嶋
智子 田嶋
水口　浩司
浩司 水口
矢板　由美
由美 矢板
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Toshiba Corp
Toshiba Energy Systems and Solutions Corp
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    • Y02E30/30—Nuclear fission reactors

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Description

本発明の実施形態は、原子炉用制御棒に関する。   Embodiments described herein relate generally to a reactor control rod.

沸騰水型原子炉の制御棒は、十字形の断面形状を有し、軸方向（鉛直方向）に延びる中央結合部材と、この中央結合部材を中心に４枚の板状のウィングが四方向に広がっている。また、ウィングは、タイロッドの軸方向に延びている。また、中央結合部材の上端部にハンドルが接合され、中央結合部材の下端部には落下速度リミッタを有する下部支持部材が取り付けられている。   The control rod of the boiling water reactor has a cross-shaped cross section, a central coupling member extending in the axial direction (vertical direction), and four plate-like wings around the central coupling member in four directions. It has spread. The wing extends in the axial direction of the tie rod. Further, a handle is joined to the upper end portion of the central coupling member, and a lower support member having a drop speed limiter is attached to the lower end portion of the central coupling member.

それぞれのウィングは、たとえば、Ｂ４Ｃなどの中性子吸収材を内包しており、中性子吸収材を、オーステナイト系ステンレス鋼製の概略Ｕ字形の断面形状を持つシースが覆っている。 Each wing includes, for example, a neutron absorber such as B 4 C, and the neutron absorber is covered with a sheath having a substantially U-shaped cross section made of austenitic stainless steel.

特開２０１１−１７４８２８号公報JP 2011-174828 A 特開２０１３−２４６１０２号公報JP 2013-246102 A

原子力発電所におけるシビアアクシデントでは、冷却材による炉心の冷却が不足し、炉心溶融が生じるような事象が想定される。このような事象においては、炉心燃料のほか、制御棒も溶融落下する。制御棒に使用される炭化ホウ素（Ｂ４Ｃ）は、制御棒の構造材部分（ウィング）に用いられるオーステナイト系ステンレス鋼と共晶を起こして融点が低下し、早期に溶融することが懸念される。 In a severe accident at a nuclear power plant, it is assumed that the core will be melted due to insufficient cooling of the core with coolant. In such an event, the control rods melt and fall in addition to the core fuel. Boron carbide (B 4 C) used for control rods is likely to eutectic with the austenitic stainless steel used for the structural material parts (wings) of the control rods, resulting in a lower melting point and melting at an early stage. The

制御棒の溶融後、原子炉への注水により、原子炉が再び臨界となる「再臨界」事象が考えられる。再臨界は原子炉圧力容器や原子炉格納容器、あるいは原子炉建屋の損傷を引き起こし、放射性物質の環境への放出につながる可能性がある。   After the control rod melts, a “recritical” event can be considered where the reactor becomes critical again due to water injection into the reactor. Recriticality can cause damage to the reactor pressure vessel, the containment vessel, or the reactor building, and can lead to the release of radioactive material to the environment.

図７は、制御棒用の構造材等の融点を示す図である。図７に示したように、オーステナイト系ステンレス鋼の融点は１７２３Ｋである。したがって、オーステナイト系ステンレス鋼製の制御棒の融点は、融点が３１２３ＫのＵＯ２より低い。また、Ｂ４Ｃ自体は融点２７２３Ｋであるが、さらに、オーステナイト系ステンレス鋼との共晶によって融点は１５００Ｋまで低下する。このため、炉内の温度状況によっては制御棒が先に溶け落ちる可能性がある。その後、燃料溶融が部分的な範囲に留まり、溶融した燃料によりある高さの炉心が形成され、その後注水により、ある高さで、再臨界が起きる可能性がある。 FIG. 7 is a diagram showing a melting point of a structural material for a control rod. As shown in FIG. 7, the melting point of austenitic stainless steel is 1723K. Therefore, the melting point of the control rod made of austenitic stainless steel is lower than UO 2 having a melting point of 3123K. Further, B 4 C itself has a melting point of 2723 K, and further, the melting point decreases to 1500 K due to the eutectic with austenitic stainless steel. For this reason, there is a possibility that the control rod melts first depending on the temperature in the furnace. Thereafter, fuel melting remains in a partial range, and a core of a certain height is formed by the melted fuel, and then water injection can cause recriticality at a certain height.

また、溶融炉心は崩壊熱の発生により温度が高い。また、燃料形状が崩壊している場合、内部まで冷却するには十分な冷却材の確保が難しい。このため、水は水蒸気として存在する可能性が高い。この場合、核***で発生した高速の中性子を、核***を起こしやすい熱中性子に減速するための減速材である水素の量が不足しているため、臨界に至る可能性は小さい。一方、時間の経過とともに、崩壊熱は減少するため、炉心溶融から数ヶ月以上も時間が経過した後には、炉内の冷却材は水蒸気ではなく液体の水の状態となってくる。このため、臨界に至る可能性がある。また、初期には存在していた上述の制御棒中のホウ素が時間経過に伴い冷却材とともに流出し、反応度抑制効果が低減することにより臨界となる可能性がある。   Also, the melting core has a high temperature due to the generation of decay heat. Further, when the fuel shape is collapsed, it is difficult to secure a sufficient coolant for cooling to the inside. For this reason, water is likely to exist as water vapor. In this case, the possibility of reaching criticality is small because the amount of hydrogen, which is a moderator for decelerating fast neutrons generated by fission into thermal neutrons that are prone to fission, is insufficient. On the other hand, the decay heat decreases with the passage of time, and therefore, after several months have passed since the melting of the core, the coolant in the furnace becomes liquid water instead of water vapor. This can lead to criticality. In addition, boron in the above-described control rod that was present at the beginning may flow out with the coolant as time passes, and may become critical due to a reduction in the reactivity suppression effect.

そこで、本発明の実施形態は、原子力発電所のシビアアクシデント時に燃料より早期に溶融せず、かつ溶融落下した場合も長期にわたり炉心に中性子吸収材が留まる事故耐性制御棒を提供することを目的とする。   Accordingly, an embodiment of the present invention aims to provide an accident resistance control rod that does not melt earlier than the fuel at the time of a severe accident at a nuclear power plant, and that the neutron absorber remains in the core for a long time even when melted and dropped. To do.

上述の目的を達成するため、本実施形態に係る原子炉用制御棒は、中性子吸収材を有する中性子吸収部と、前記中性子吸収部を内包する複数の収納部材と、前記複数の収納部材を一体化する結合部材と、中性子吸収効果および高温安定性を有する共晶防止用酸化物を含み、前記中性子吸収部と前記収納部材の間に設けられて前記中性子吸収部と前記収納部材との直接的な接触を防止する共晶防止部材と、を備え、前記共晶防止用酸化物は最高酸化数まで酸素と結合していることを特徴とする。
また、本実施形態に係る原子炉用制御棒は、中性子吸収材を有する中性子吸収部と、前記中性子吸収部を内包する複数の収納部材と、前記複数の収納部材を一体化する結合部材と、中性子吸収効果および高温安定性を有する共晶防止用酸化物を含み、前記中性子吸収部前記収納部材の間に設けられて前記中性子吸収部と前記収納部材との直接的な接触を防
止する共晶防止部材と、を備え、前記共晶防止部材は容器状に形成され、前記中性子吸収部は前記容器状の前記共晶防止部材内に収納されていることを特徴とする。 In order to achieve the above-described object, a reactor control rod according to the present embodiment includes a neutron absorber having a neutron absorber, a plurality of storage members containing the neutron absorber, and the plurality of storage members integrated. And an eutectic-preventing oxide having a neutron absorption effect and high-temperature stability, and is provided between the neutron absorption part and the storage member and directly between the neutron absorption part and the storage member comprising a eutectic prevention member for preventing Do contact, wherein the eutectic preventing oxide is characterized that you have combined with oxygen up oxidation number.
Further, the nuclear reactor control rod according to the present embodiment includes a neutron absorber having a neutron absorber, a plurality of storage members containing the neutron absorber, a coupling member integrating the plurality of storage members, It includes an oxide for eutectic prevention having neutron absorption effect and high temperature stability, and is provided between the neutron absorption part and the storage member to prevent direct contact between the neutron absorption part and the storage member.
An eutectic prevention member that stops, wherein the eutectic prevention member is formed in a container shape, and the neutron absorption part is housed in the eutectic prevention member in the container shape.

本発明の実施形態によれば、原子力発電所のシビアアクシデント時に燃料より早期に溶融せず、かつ溶融落下した場合も長期にわたり炉心に中性子吸収材が留まる事故耐性制御棒を提供することができる。   According to the embodiment of the present invention, it is possible to provide an accident resistance control rod in which a neutron absorbing material stays in the core for a long period of time even when it melts and falls at the time of a severe accident at a nuclear power plant and even when melted and dropped.

第１の実施形態による原子炉用制御棒を炉心内に挿入した状態を示す水平断面図である。It is a horizontal sectional view showing the state where the control rod for reactors by a 1st embodiment was inserted in the core. 第１の実施形態による原子炉用制御棒のウィングの構成を示す概念的斜視図である。It is a conceptual perspective view which shows the structure of the wing | wing of the nuclear reactor control rod by 1st Embodiment. 第１の実施形態による原子炉用制御棒のウィングに挿入される中性子吸収部の構成を示す概念的斜視図である。It is a conceptual perspective view which shows the structure of the neutron absorption part inserted in the wing of the control rod for reactors by 1st Embodiment. 第１の実施形態による原子炉用制御棒のウィングの構成を示す図２の第ＩＶ−ＩＶ矢視概念的縦断面図である。FIG. 4 is a conceptual longitudinal sectional view taken along arrows IV-IV in FIG. 2 showing a configuration of a wing of a nuclear reactor control rod according to the first embodiment. 第２の実施形態による原子炉用制御棒のウィングの構成を示す概念的縦断面図である。It is a notional longitudinal cross-sectional view which shows the structure of the wing | wing of the control rod for reactors by 2nd Embodiment. 第３の実施形態による原子炉用制御棒のウィングの構成を示す概念的縦断面図である。It is a notional longitudinal cross-sectional view which shows the structure of the wing | wing of the control rod for reactors by 3rd Embodiment. 制御棒構造材等の融点を示す図である。It is a figure which shows melting | fusing point of a control-rod structure material.

以下、図面を参照して、本発明の実施形態に係る原子炉用制御棒について説明する。ここで、互いに同一または類似の部分には、共通の符号を付して、重複説明は省略する。   Hereinafter, a control rod for a nuclear reactor according to an embodiment of the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.

［第１の実施形態］
図１は、第１の実施形態による原子炉用制御棒を炉心内に挿入した状態を示す水平断面図である。原子炉用制御棒１０は、図示しない炉心内に格子状に配列された四角柱状の燃料集合体１の間隙に鉛直下方から挿入可能に位置決めされている。 [First Embodiment]
FIG. 1 is a horizontal sectional view showing a state in which a nuclear reactor control rod according to a first embodiment is inserted into a core. The nuclear reactor control rod 10 is positioned so that it can be inserted into the gap between the rectangular columnar fuel assemblies 1 arranged in a lattice pattern in a core (not shown) from below.

原子炉用制御棒１０は、水平方向および鉛直方向に広がった板状の４つのウィング２０と、これらを結合して一体化して鉛直方向に延びる棒状の中央結合部材１１とを有する。４つのウィング２０は、中央結合部材１１を中心に水平方向に十字型に延びている。また、原子炉用制御棒１０は、正方形状の４体の燃料集合体１の水平方向のほぼ中央に中央結合部材１１が位置し、それぞれのウィング２０が互いに隣接する燃料集合体１に挟まれるように配列されている。   The nuclear reactor control rod 10 includes four plate-like wings 20 extending in the horizontal direction and the vertical direction, and a rod-like central coupling member 11 that is coupled and integrated to extend in the vertical direction. The four wings 20 extend in a cross shape in the horizontal direction around the central coupling member 11. Further, in the nuclear reactor control rod 10, a central coupling member 11 is positioned at the substantially horizontal center of four square fuel assemblies 1, and each wing 20 is sandwiched between adjacent fuel assemblies 1. Are arranged as follows.

図２は、原子炉用制御棒のウィングの構成を示す概念的斜視図である。図３は、原子炉用制御棒のウィングに挿入される中性子吸収部の構成を示す概念的斜視図である。また、図４は、図２の第ＩＶ−ＩＶ矢視概念的縦断面図である。   FIG. 2 is a conceptual perspective view showing the configuration of the wing of the nuclear reactor control rod. FIG. 3 is a conceptual perspective view showing a configuration of a neutron absorbing portion inserted into the wing of the nuclear reactor control rod. FIG. 4 is a conceptual vertical cross-sectional view taken along arrow IV-IV in FIG.

ウィング２０は、収納部材２１および収納部材２１内に収納される中性子吸収部３１を有する。収納部材２１は、水平断面の外形がＵ字型形状で、軸方向すなわち、据付状態で鉛直方向に延びている。収納部材２１は、たとえば、ウィング２０の水平に広がる方向の先端部分を滑らかな曲面にする等、板材から削り出して成形される。   The wing 20 includes a storage member 21 and a neutron absorption part 31 stored in the storage member 21. The storage member 21 has a U-shaped outer shape in a horizontal section, and extends in the axial direction, that is, in the vertical direction in the installed state. The storage member 21 is formed by cutting out from a plate material, for example, by making the tip portion of the wing 20 in a horizontally extending direction a smooth curved surface.

収納部材２１には、水平でウィング２０の広がり方向に、鉛直方向に互いに間隔をあけて複数の円筒状の収納穴２２が形成されている。収納穴２２は、中央結合部材１１（図１）と結合する側は開放されており、反対側すなわちウィング２０が水平方向に広がる側には貫通せず閉じている。収納穴２２は、収納部材２１にたとえば中央結合部材１１と結合する側からの穴加工により形成される。収納部材２１の材料は、たとえばオーステナイト系ステンレス鋼である。   The storage member 21 is formed with a plurality of cylindrical storage holes 22 that are horizontally spaced apart from each other in the vertical direction of the wing 20. The storage hole 22 is open on the side coupled to the central coupling member 11 (FIG. 1), and is closed without penetrating on the opposite side, that is, the side where the wing 20 extends in the horizontal direction. The storage hole 22 is formed in the storage member 21 by, for example, drilling from the side where it is coupled to the central coupling member 11. The material of the storage member 21 is, for example, austenitic stainless steel.

それぞれの収納穴２２には、中性子吸収部３１が収納されている。中性子吸収部３１は、固体であり、円筒形状に形成されている。中性子吸収部３１の材料は、たとえば、焼結されたＢ４Ｃである。 A neutron absorbing portion 31 is stored in each storage hole 22. The neutron absorber 31 is solid and is formed in a cylindrical shape. The material of the neutron absorber 31 is, for example, sintered B 4 C.

中性子吸収部３１の外面には、共晶防止部材３３が設けられている。共晶防止部材３３は、中性子吸収部３１と収納部材２１とが直接に接触することを防止するように配されている。したがって、共晶防止部材３３は、必ずしも、中性子吸収部３１の外面を完全に覆っている必要はないが、収納部材２１の部分的溶融などの可能性を想定すれば完全に覆っていることが好ましい。   A eutectic prevention member 33 is provided on the outer surface of the neutron absorber 31. The eutectic prevention member 33 is arranged so as to prevent the neutron absorbing portion 31 and the storage member 21 from coming into direct contact. Therefore, the eutectic prevention member 33 does not necessarily need to completely cover the outer surface of the neutron absorption part 31, but may completely cover the possibility of partial melting of the storage member 21. preferable.

収納穴２２内への共晶防止部材３３が設けられた中性子吸収部３１の挿入性、および、収納穴２２内における共晶防止部材３３と収納部材２１との接触面積を最小とする観点から、共晶防止部材３３と収納部材２１との間にはギャップ３５が形成されている。ギャップ３５を周方向に確保するために図示しないスペーサで共晶防止部材３３を固定してもよい。あるいは、スペーサ等を使用せずに、共晶防止部材３３を収納穴２２上に乗せた状態、すなわち面接触ではなく線接触とすることでもよい。   From the viewpoint of minimizing the insertion property of the neutron absorber 31 provided with the eutectic prevention member 33 in the storage hole 22 and the contact area between the eutectic prevention member 33 and the storage member 21 in the storage hole 22. A gap 35 is formed between the eutectic prevention member 33 and the storage member 21. In order to secure the gap 35 in the circumferential direction, the eutectic prevention member 33 may be fixed with a spacer (not shown). Alternatively, the eutectic prevention member 33 may be placed on the storage hole 22 without using a spacer or the like, that is, a line contact may be used instead of a surface contact.

共晶防止部材３３の材料は、中性子吸収効果があること、高温で安定な材料であること、さらにコスト的にも入手可能であることを要件として選定する。   The material of the eutectic prevention member 33 is selected as a requirement that it has a neutron absorption effect, is a material that is stable at high temperatures, and is also available in terms of cost.

共晶防止部材３３は、後述する共晶防止部材３３用のランタノイド金属あるいはランタノイド酸化物の被膜を、溶射などにより中性子吸収部３１の外面に形成させることでもよい。あるいは、共晶防止部材３３用のランタノイド酸化物の容器として、中性子吸収部３１を収納することでもよい。この場合は、中性子吸収部３１は、固体形状に限定されずたとえば粉末状のＢ４Ｃなどでもよい。 The eutectic preventing member 33 may be formed by forming a lanthanoid metal or lanthanoid oxide film for the eutectic preventing member 33 described later on the outer surface of the neutron absorbing portion 31 by thermal spraying or the like. Alternatively, the neutron absorption part 31 may be housed as a lanthanoid oxide container for the eutectic prevention member 33. In this case, the neutron absorber 31 is not limited to a solid shape, and may be, for example, powdered B 4 C.

発明者らは、共晶防止部材３３の材料としての候補材について、１１５０℃のもとで、候補材の酸化物１モルと水蒸気１０モルでの熱力学的平衡解析（反応解析）を行い、水蒸気反応後の生成物量のモル数の当初の候補材のモル数（１モル）に対する比を求めた。ここで、１１５０℃はこの温度以上でＢ４Ｃが水蒸気と反応する温度である。すなわち、Ｂ４Ｃは１１５０℃で水蒸気との反応が開始される。 The inventors conducted a thermodynamic equilibrium analysis (reaction analysis) of the candidate material as a material of the eutectic prevention member 33 at 1150 ° C. with 1 mol of the oxide of the candidate material and 10 mol of water vapor. The ratio of the number of moles of the product amount after the steam reaction to the number of moles of the original candidate material (1 mole) was determined. Here, 1150 ° C. is a temperature at which B 4 C reacts with water vapor above this temperature. That is, the reaction of B 4 C with water vapor starts at 1150 ° C.

Ｂ４Ｃについては、前述のように、水蒸気と反応し１０倍以上のモル数の反応生成物が生じたが、希土類元素の一部と、遷移金属の一部は１モルのままで水蒸気と反応しないことがわかった。このように水蒸気と反応しない材料は、具体的には、希土類元素では、候補材としたランタノイド元素（Ｌｎ）であるガドリニウム（Ｇｄ）、ルテチウム（Ｌｕ）、ツリウム（Ｔｍ）、エルビウム（Ｅｒ）、ディスプロシウム（Ｄｙ）、ガリウム（Ｇａ）、ユーロピウム（Ｅｕ）、およびサマリウム（Ｓｍ）のそれぞれの酸化物であり、これらの反応解析の結果は全て１モルのままで水蒸気と反応していなかった。遷移金属としては、水銀（Ｈｇ）、ハフニウム（Ｈｆ）、カドミウム（Ｃｄ）、および銀（Ａｇ）の酸化物についても同様に水蒸気との反応が見られなかった。 As described above, B 4 C reacted with water vapor to produce a reaction product having a molar number of 10 times or more. However, a part of the rare earth element and a part of the transition metal remained at 1 mole, It turns out that it does not react. Specifically, the material that does not react with water vapor is, as a rare earth element, gadolinium (Gd), lutetium (Lu), thulium (Tm), erbium (Er), which are candidate lanthanoid elements (Ln), These oxides were dysprosium (Dy), gallium (Ga), europium (Eu), and samarium (Sm), and the results of these reaction analyzes were all 1 mol and did not react with water vapor. . As transition metals, mercury (Hg), hafnium (Hf), cadmium (Cd), and silver (Ag) oxides did not react with water vapor as well.

これらのうち、Ｇｄ、Ｅｕ、Ｄｙ、Ｓｍ、Ｅｒ、Ｈｆ、およびＣｄは、中性子吸収断面積の大きな核種である。また、これらの酸化物は安定形態であり、したがって、オーステナイト系ステンレス鋼との共晶も生じない材料である。したがって、これらの材料は、入手可能な安定材料である。以下、これらのうち、特に、ランタノイド元素であるＧｄ、Ｅｕ、Ｄｙ、Ｓｍ、Ｅｒのそれぞれの酸化物を、共晶防止用酸化物と呼ぶこととする。   Among these, Gd, Eu, Dy, Sm, Er, Hf, and Cd are nuclides having a large neutron absorption cross section. Further, these oxides are in a stable form, and are therefore materials that do not cause eutectic with austenitic stainless steel. These materials are therefore available stable materials. Hereinafter, among these, the oxides of lanthanoid elements Gd, Eu, Dy, Sm, and Er will be referred to as oxides for preventing eutectic.

元素がとりうる最高酸化数は、希土類元素のランタノイド元素ではほとんどが３であり、Ｈｆでは４である。この最高酸化数まで酸素と結合していれば、それ以上の酸化反応は生じないため水蒸気と反応して水素を発生することがないことが反応解析の結果からもわかっている。前述のランタノイド元素の酸化物Ｌｎ２Ｏ３、Ｈｆの酸化物ＨｆＯ２は融点が２０００℃以上であり熱安定性も高い。したがって、水素発生抑制可能な候補材料として最も有効な形態である。 The highest oxidation number that the element can take is almost 3 for lanthanoid elements of rare earth elements and 4 for Hf. From the results of the reaction analysis, it is known that if it is combined with oxygen up to this maximum oxidation number, no further oxidation reaction occurs, so that it does not react with water vapor to generate hydrogen. The above-described lanthanoid element oxide Ln 2 O 3 and Hf oxide HfO 2 have a melting point of 2000 ° C. or higher and high thermal stability. Therefore, it is the most effective form as a candidate material capable of suppressing hydrogen generation.

なお、Ｓｍ、Ｇｄ、Ｅｕの酸化物は、Ｂ型と言われる高温型の単斜晶系と、Ｃ型と言われる低温型の立方晶系の２つの形態をとりうる。例えばＥｕは１０００℃で相転移が起こり安定相の結晶系が変わる。すなわち、事故による昇温の過程で相転移が起こり、密度が変化すると構造的な破壊を生じる可能性があるため好ましくない。また、Ｅｕの原子密度は高温相の方が大きいため高温相の方が制御棒材料としては望ましい。また、１０００〜１３００℃での相転移は不可逆的であるとわれている。このため、あらかじめ高温型の結晶系とした酸化物を用いることにより、当初より安定な高温相の状態で使用できる。   Note that the oxides of Sm, Gd, and Eu can take two forms: a high-temperature monoclinic system called B-type and a low-temperature cubic system called C-type. For example, Eu undergoes a phase transition at 1000 ° C. and changes the crystal system of the stable phase. That is, phase transition occurs in the process of temperature rise due to an accident, and if the density is changed, structural destruction may occur, which is not preferable. Also, since the atomic density of Eu is higher in the high temperature phase, the high temperature phase is preferable as the control rod material. Moreover, it is said that the phase transition in 1000-1300 degreeC is irreversible. For this reason, it can be used in the state of the stable high temperature phase from the beginning by using the oxide made into the high temperature type crystal system beforehand.

以上の説明のように本実施形態における共晶防止部材３３は、材料として、共晶防止用酸化物を有する。   As described above, the eutectic prevention member 33 in the present embodiment has an eutectic prevention oxide as a material.

本実施形態による原子炉用制御棒１０においては、高融点でかつ高温で安定な共晶防止用酸化物を有する共晶防止部材３３が、中性子吸収部３１の外周に配されている。このため、原子炉用制御棒１０の周囲温度が上昇した場合であっても、共晶防止部材３３が収納部材２１と収納部材２１内に収納された中性子吸収部３１間に介在する状態が持続する。この結果、オーステナイト系ステンレス鋼製の収納部材２１と、収納部材２１内に収納された中性子吸収部３１とが直接接触することがなく、共晶が生じない。したがって、原子炉用制御棒１０は、従来よりも高い温度まで、その構成を維持することができる。さらに、事故時の高温水蒸気との反応により水素を発生しない物質を用いることでより安全性の高い原子炉用制御棒１０となる。   In the nuclear reactor control rod 10 according to the present embodiment, a eutectic prevention member 33 having an eutectic prevention oxide that has a high melting point and is stable at a high temperature is disposed on the outer periphery of the neutron absorber 31. For this reason, even when the ambient temperature of the nuclear reactor control rod 10 rises, the state in which the eutectic prevention member 33 is interposed between the storage member 21 and the neutron absorbing portion 31 stored in the storage member 21 continues. To do. As a result, the storage member 21 made of austenitic stainless steel and the neutron absorbing portion 31 stored in the storage member 21 are not in direct contact, and no eutectic is generated. Therefore, the configuration of the nuclear reactor control rod 10 can be maintained up to a higher temperature than before. Furthermore, the use of a substance that does not generate hydrogen due to reaction with high-temperature steam at the time of an accident makes the nuclear reactor control rod 10 safer.

また、共晶防止部材３３に使用される共晶防止用酸化物は中性子吸収効果を有しており、原子炉用制御棒１０の反応度価値をさらに高め、あるいは寿命をさらに延ばすことができる。   Further, the eutectic prevention oxide used for the eutectic prevention member 33 has a neutron absorption effect, and can further increase the reactivity value of the nuclear reactor control rod 10 or further extend the life.

［第２の実施形態］
図５は、第２の実施形態による原子炉用制御棒のウィングの構成を示す概念的縦断面図である。本実施形態は、第１の実施形態の変形である。 [Second Embodiment]
FIG. 5 is a conceptual longitudinal sectional view showing a configuration of a wing of a nuclear reactor control rod according to the second embodiment. This embodiment is a modification of the first embodiment.

本第２の実施形態に係る原子炉用制御棒１０においては、共晶防止部材３３は、収納部材２１に形成されたそれぞれの収納穴２２の内面に沿って同心円状に形成されている。共晶防止部材３３の径方向の外面の径は、収納穴２２の内面の径とほぼ同程度に形成されている。   In the nuclear reactor control rod 10 according to the second embodiment, the eutectic prevention member 33 is formed concentrically along the inner surface of each storage hole 22 formed in the storage member 21. The diameter of the outer surface in the radial direction of the eutectic prevention member 33 is formed to be approximately the same as the diameter of the inner surface of the storage hole 22.

この場合、共晶防止部材３３は、たとえば、円筒状の容器形状に成形したものを、収納穴２２の内面に沿って挿入することにより設けてもよい。あるいは、ウィング２０の外形の鋳型の中に、円筒状の容器形状の共晶防止部材３３を互いに間隔をあけて一列に並べて、鋳造によりオーステナイト系ステンレス鋼の収納部材２１を成形することによってもよい。   In this case, the eutectic prevention member 33 may be provided, for example, by inserting what is formed into a cylindrical container shape along the inner surface of the storage hole 22. Alternatively, a cylindrical container-shaped eutectic prevention member 33 may be arranged in a line at intervals in a mold having an outer shape of the wing 20, and the austenitic stainless steel storage member 21 may be formed by casting. .

共晶防止部材３３の内面と、中性子吸収部３１の外面との間には、ギャップ３６が形成されている。なお、ギャップの幅は、周角度方向に均一である必要はない。すなわち、共晶防止部材３３と中性子吸収部３１は一方で接触していてもよい。   A gap 36 is formed between the inner surface of the eutectic prevention member 33 and the outer surface of the neutron absorber 31. Note that the gap width need not be uniform in the circumferential angle direction. That is, the eutectic prevention member 33 and the neutron absorber 31 may be in contact with each other.

中性子吸収部３１は共晶防止部材３３に比べ熱膨張率が大きい場合、温度上昇の際に中性子吸収部３１の熱膨張を共晶防止部材３３が拘束することになる。本実施形態においては、中性子吸収部３１の外面と共晶防止部材３３の内面間にギャップ３６を確保することによって、共晶防止部材３３によるたが締めにより中性子吸収部３１が損壊あるいは崩壊する可能性を排除することができる。   When the thermal expansion coefficient of the neutron absorbing portion 31 is larger than that of the eutectic preventing member 33, the eutectic preventing member 33 restrains the thermal expansion of the neutron absorbing portion 31 when the temperature rises. In the present embodiment, by securing a gap 36 between the outer surface of the neutron absorbing portion 31 and the inner surface of the eutectic preventing member 33, the neutron absorbing portion 31 can be damaged or collapsed by tapping with the eutectic preventing member 33. Sex can be excluded.

［第３の実施形態］
図６は、第３の実施形態による原子炉用制御棒のウィングの構成を示す概念的縦断面図である。本実施形態は、第１または第２の実施形態の変形である。 [Third Embodiment]
FIG. 6 is a conceptual longitudinal sectional view showing a configuration of a wing of a nuclear reactor control rod according to the third embodiment. This embodiment is a modification of the first or second embodiment.

本第３の実施形態に係る原子炉用制御棒１０においては、共晶防止部材３３は、長手方向に延びた円筒形状である。共晶防止部材３３の外面と収納穴２２の内面との間には、ギャップ３５が形成されている。また、共晶防止部材３３の内面と中性子吸収部３１の外面の間には、ギャップ３６が形成されている。ギャップ３５およびギャップ３６は、周方向に均一である必要はない。すなわち、共晶防止部材３３と収納穴２２、共晶防止部材３３と中性子吸収部３１は、それぞれ一方で接触していてもよい。   In the nuclear reactor control rod 10 according to the third embodiment, the eutectic prevention member 33 has a cylindrical shape extending in the longitudinal direction. A gap 35 is formed between the outer surface of the eutectic prevention member 33 and the inner surface of the storage hole 22. In addition, a gap 36 is formed between the inner surface of the eutectic prevention member 33 and the outer surface of the neutron absorber 31. The gap 35 and the gap 36 do not need to be uniform in the circumferential direction. That is, the eutectic prevention member 33 and the storage hole 22, and the eutectic prevention member 33 and the neutron absorber 31 may be in contact with each other.

中性子吸収部３１と収納穴２２間にギャップを設けることによって、中性子吸収部３１と収納部材２１との温度変化による機械的な相互作用を低減し、中性子吸収部３１、共晶防止部材３３および収納部材２１それぞれの構造健全性を向上させることができる。   By providing a gap between the neutron absorber 31 and the storage hole 22, mechanical interaction due to temperature change between the neutron absorber 31 and the storage member 21 is reduced, and the neutron absorber 31, the eutectic prevention member 33 and the storage are reduced. The structural soundness of each member 21 can be improved.

［その他の実施形態］
以上、本発明のいくつかの実施形態を説明したが、これらの実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。たとえば、実施形態では、ウィング２０の収納部材２１はたとえば板材から成形され、収納穴２２は穴加工により形成される場合を示したが、これには限らない。たとえば、板を曲げてＵ字型に成形した容器状の収納部材に固体状の中性子吸収部３１を並べて収納する構成のウィングでも、本発明は適用できる。 [Other Embodiments]
As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. For example, in the embodiment, the storage member 21 of the wing 20 is formed from, for example, a plate material, and the storage hole 22 is formed by drilling. However, the present invention is not limited to this. For example, the present invention can also be applied to a wing having a configuration in which the solid neutron absorbing portions 31 are stored side by side in a container-shaped storage member formed by bending a plate into a U shape.

また、実施形態では、中性子吸収部３１の材料がＢ４Ｃの場合を示したが、これに限定されない。たとえば、金属ハフニウム（Ｈｆ）などの場合でもよい。 Further, in the embodiment, the material of the neutron absorbing portion 31 shows the case of B 4 C, but is not limited thereto. For example, metal hafnium (Hf) may be used.

また、各実施形態の特徴を組み合わせてもよい。さらに、これらの実施形態は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。   Moreover, you may combine the characteristic of each embodiment. Furthermore, these embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

これら実施形態やその変形は、発明の範囲や要旨に含まれると同様に、特許請求の範囲に記載された発明とその均等の範囲に含まれるものである。   These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

１…燃料集合体、１０…原子炉用制御棒、１１…中央結合部材（結合部材）、２０…ウィング、２１…シース部（収納部材）、２２…収納穴、３１…中性子吸収部、３３…共晶防止部材、３５、３６…ギャップ   DESCRIPTION OF SYMBOLS 1 ... Fuel assembly, 10 ... Reactor control rod, 11 ... Central coupling member (coupling member), 20 ... Wing, 21 ... Sheath part (housing member), 22 ... Storage hole, 31 ... Neutron absorption part, 33 ... Eutectic prevention member, 35, 36 ... gap

Claims (7)

中性子吸収材を有する中性子吸収部と、
前記中性子吸収部を内包する複数の収納部材と、
前記複数の収納部材を一体化する結合部材と、
中性子吸収効果および高温安定性を有する共晶防止用酸化物を含み、前記中性子吸収部と前記収納部材の間に設けられて前記中性子吸収部と前記収納部材との直接的な接触を防止する共晶防止部材と、
を備え、
前記共晶防止用酸化物は最高酸化数まで酸素と結合していることを特徴とする原子炉用制御棒。 A neutron absorber having a neutron absorber;
A plurality of storage members enclosing the neutron absorber;
A coupling member that integrates the plurality of storage members;
A co-crystal preventing oxide having a neutron absorption effect and high-temperature stability is provided between the neutron absorption part and the storage member to prevent direct contact between the neutron absorption part and the storage member. An anti-crystallizing member;
Equipped with a,
A control rod for a nuclear reactor, wherein the oxide for preventing eutectic is bonded to oxygen up to the maximum oxidation number . 前記複数の収納部材のそれぞれは、上下方向に延びる軸のまわりに放射状に周方向の間隔をあけて配置されて前記軸の方向および放射方向に広がる平板状であり、
前記結合部材は、前記複数の収納部材を中央で結合する軸方向に延びた棒状である、
ことを特徴とする請求項１に記載の原子炉用制御棒。 Each of the plurality of storage members has a flat plate shape that is radially arranged around an axis extending in the vertical direction and spaced in the circumferential direction and extends in the direction of the axis and the radial direction,
The coupling member has a rod shape extending in the axial direction for coupling the plurality of storage members at the center.
The control rod for a nuclear reactor according to claim 1, wherein: 前記共晶防止用酸化物は、ガドリニウム酸化物、ユーロピウム酸化物、ディスプロシウム酸化物、サマリウム酸化物、エルビウム酸化物の少なくとも一つを含むことを特徴とする請求項１または請求項２に記載の原子炉用制御棒。   The oxide for preventing eutectic includes at least one of gadolinium oxide, europium oxide, dysprosium oxide, samarium oxide, and erbium oxide. Control rod for nuclear reactors. 前記中性子吸収部は固体形状であり、前記共晶防止部材は、前記中性子吸収部の周囲に密着するように形成されていることを特徴とする請求項１ないし請求項３のいずれか一項に記載の原子炉用制御棒。   The said neutron absorption part is a solid shape, The said eutectic prevention member is formed so that it may closely_contact | adhere to the circumference | surroundings of the said neutron absorption part, The Claim 1 thru | or 3 characterized by the above-mentioned. The reactor control rod as described. 前記共晶防止部材は容器状に形成され、前記中性子吸収部は前記容器状の前記共晶防止部材内に収納されていることを特徴とする請求項１ないし請求項３のいずれか一項に記載の原子炉用制御棒。   The said eutectic prevention member is formed in a container shape, The said neutron absorption part is accommodated in the said eutectic prevention member of the said container shape, The Claim 1 thru | or 3 characterized by the above-mentioned. The reactor control rod as described. 前記複数の収納部材のそれぞれには、前記中性子吸収部を収納するための複数の収納穴が形成されており、前記共晶防止部材は、前記収納穴の内面に沿って設けられていることを特徴とする請求項１ないし請求項３のいずれか一項に記載の原子炉用制御棒。   Each of the plurality of storage members is formed with a plurality of storage holes for storing the neutron absorbing portion, and the eutectic prevention member is provided along the inner surface of the storage hole. The control rod for a nuclear reactor according to any one of claims 1 to 3, wherein the control rod is a reactor. 中性子吸収材を有する中性子吸収部と、  A neutron absorber having a neutron absorber;
前記中性子吸収部を内包する複数の収納部材と、  A plurality of storage members enclosing the neutron absorber;
前記複数の収納部材を一体化する結合部材と、  A coupling member that integrates the plurality of storage members;
中性子吸収効果および高温安定性を有する共晶防止用酸化物を含み、前記中性子吸収部  A neutron absorption part comprising an oxide for eutectic prevention having neutron absorption effect and high temperature stability,
と前記収納部材の間に設けられて前記中性子吸収部と前記収納部材との直接的な接触を防Provided between the storage member and the neutron absorbing portion to prevent direct contact between the storage member.
止する共晶防止部材と、Eutectic prevention member to stop,
を備え、  With
前記共晶防止部材は容器状に形成され、前記中性子吸収部は前記容器状の前記共晶防止  The eutectic prevention member is formed in a container shape, and the neutron absorption part is formed in the container shape of the eutectic prevention member.
部材内に収納されていることを特徴とする原子炉用制御棒。A control rod for a nuclear reactor, which is housed in a member.
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