JP2004093269A - Neutron multiplier for fusion reactors with excellent high temperature properties and ductility - Google Patents
Neutron multiplier for fusion reactors with excellent high temperature properties and ductility Download PDFInfo
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- 230000004927 fusion Effects 0.000 title claims abstract description 13
- 229910052790 beryllium Inorganic materials 0.000 claims abstract description 35
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 claims abstract description 31
- 229910000765 intermetallic Inorganic materials 0.000 claims abstract description 24
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 9
- 239000002131 composite material Substances 0.000 claims abstract description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 5
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 5
- 229910052715 tantalum Inorganic materials 0.000 claims abstract description 5
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 5
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 5
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 5
- 239000000126 substance Substances 0.000 claims abstract description 3
- 239000013078 crystal Substances 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 13
- 230000008569 process Effects 0.000 abstract description 2
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- 230000008961 swelling Effects 0.000 description 15
- 230000000694 effects Effects 0.000 description 12
- 239000000463 material Substances 0.000 description 12
- 230000009257 reactivity Effects 0.000 description 12
- YZCKVEUIGOORGS-NJFSPNSNSA-N Tritium Chemical compound [3H] YZCKVEUIGOORGS-NJFSPNSNSA-N 0.000 description 10
- 239000004005 microsphere Substances 0.000 description 10
- 229910052722 tritium Inorganic materials 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
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- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
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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
- Y02E30/10—Nuclear fusion reactors
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Abstract
【課題】高温での特性に優れるのは言うまでもなく、高い延性をそなえ、その加工や取り扱いが極めて容易な、高温特性に優れた核融合炉用中性子増倍材を提供する。
【解決手段】化学式：Ｂｅ−ｘａｔ％Ｍ
但し、Ｍは、Ｔｉ，Ｖ，Ｍｏ，Ｗ，Ｚｒ，ＮｂおよびＴａのうちから選んだいずれか一種
７．７＜ｘ＜１０．５（ａｔ％）
で表わされる、Ｂｅ１２ＭまたはＢｅ１３ＭとＢｅ１７Ｍ２とのベリリウム金属間化合物の複合相を形成する。
【選択図】 なしIt is an object of the present invention to provide a neutron multiplier for a nuclear fusion reactor, which has excellent ductility, high ductility, and is extremely easy to process and handle.
Chemical formula: Be-xat% M
However, M is one kind selected from Ti, V, Mo, W, Zr, Nb and Ta 7.7 <x <10.5 (at%)
And a composite phase of a beryllium intermetallic compound of Be 12 M or Be 13 M and Be 17 M 2 is formed.
[Selection figure] None
Description
【０００１】
【発明の属する技術分野】本発明は、高温特性および延性に優れた核融合炉用中性子増倍材に関するものである。
【０００２】
【従来の技術】従来、核融合炉用中性子増倍材としては、金属ベリリウム微小球が標準材料とされてきた。というのは、この金属ベリリウム微小球は、中性子反応断面積が大きく、中性子の数を増やす中性子増倍効果に優れることから、効果的に中性子を増やすことができ、その結果増倍した中性子により燃料であるトリチウムを増殖させることができるため、核融合燃料サイクルの有利な向上が望めるからである。
【０００３】ところが、近年、核融合炉の発電効率を高め、寿命を延長するために、中性子増倍材をより高温（ ６００〜９００ ℃）、かつより高い中性子照射環境下（〜２００００ ａｐｐｍＨｅ）で使用する計画が進められている。
しかしながら、上記した金属ベリリウムは、従来の使用環境下では問題はないものの、より高温での使用に際しては種々の問題が取り沙汰されている。
【０００４】すなわち、金属ベリリウムは、従来考えられていた ４００℃程度までの使用温度、３０００ ａｐｐｍＨｅ 程度までの中性子照射環境では、核融合炉用中性子増倍材として問題はないけれども、使用温度が ６００℃以上になると冷却管破断等の事故発生時に高温水蒸気により酸化されて水素を生成して、水素爆発等の危険性が高まり、またスエリングが大きくなって、容器の破損等を生じるおそれがあり、かような高温発電ブランケットの中性子増倍材としては使用できない可能性がある。
【０００５】従って、現在、高温で使用できる中性子増倍材の開発が進められている。
このような高温で使用できる中性子増倍材としては、ベリリウム金属間化合物が注目を浴びている。
例えば、ベリリウム金属間化合物の一つであるＢｅ１２Ｔｉは、６００ ℃の蒸気と接しても酸化せず、またブランケット構造材であるＳＵＳ３１６ＬＮとの両立性試験においても ６００℃ではほとんど反応せず、さらに ８００℃における反応層厚さは金属ベリリウムの約１／１０であり、化学的に極めて安定であることが判明している。また、中性子照射試験でのスエリング特性についての調査結果からも、Ｂｅ１２Ｔｉは金属ベリリウムに比べてスエリング量が格段に小さいことが解明されている。
このように、ベリリウム金属間化合物は、高温での中性子増倍材として優れた特性を有することが明らかになってきている。
【０００６】しかしながら、ベリリウム金属間化合物は、室温において脆いため、その加工や取り扱いが極めて難しいところに問題を残していた。
すなわち、機械加工中に欠け等の欠陥が発生し易いことから、歩留りや生産性の低下を余儀なくされ、また微小球とした後も割れが発生しないように、その取り扱いに細心の注意が必要なことから、その実使用が危ぶまれていた。
【０００７】ところで、発明者らは先に、上記の問題を解決するものとして、少なくとも一種のベリリウム金属間化合物相と金属相との複合相からなる核融合炉用中性子増倍材を開発し、特願２００２−１０５７４２号明細書において開示した。
上記の技術によれば、金属相がベリリウム金属間化合物相間にバインダーとして介在するため、ベリリウム金属間化合物相同士の固着強度が増大し、その結果、中性子増倍材全体の延性が向上して、加工性や取り扱い性の有利な改善を図ることができる。
【０００８】
【発明が解決しようとする課題】しかしながら、上記の技術では、金属相を介在させたことに起因する特性劣化が免れ得ない。すなわち、僅かとはいえ金属相を介在させると、その分、中性子増倍効果が低下するだけでなく、スエリング特性、構造材との反応性、蒸気との反応性およびトリチウムインベントリ等の金属間化合物の特性劣化が生じる。
また、金属相として、金属ベリリウムを用いたとしても、αＢｅ相に起因して、上記したところと同様な金属間化合物の特性劣化が生じる。
本発明は、上記の問題を有利に解決するもので、バインダーとしての金属相の必要なしに、ベリリウム金属間化合物相のみで延性を有利に改善した、高温特性および延性に優れた核融合炉用中性子増倍材を提案することを目的とする。
【０００９】
【課題を解決するための手段】さて、発明者らは、上記の問題を解決すべく鋭意研究を重ねた結果、単味のベリリウム金属間化合物を使用した場合に比べて、特定組成比のベリリウム金属間化合物同士を組み合わせた場合に、延性が有利に改善されることの知見を得た。
本発明は、上記の知見に由来するものである。
【００１０】すなわち、本発明は、
化学式：Ｂｅ−ｘａｔ％Ｍ
但し、Ｍは、Ｔｉ，Ｖ，Ｍｏ，Ｗ，Ｚｒ，ＮｂおよびＴａのうちから選んだいずれか一種
７．７＜ｘ＜１０．５（ａｔ％）
で表わされる、Ｂｅ１２ＭまたはＢｅ１３ＭとＢｅ１７Ｍ２とのベリリウム金属間化合物の複合相からなることを特徴とする高温特性および延性に優れた核融合炉用中性子増倍材である。
【００１１】
本発明において、中性子増倍材の組織は、鋳造組織で、かつ結晶粒径が５０μｍ 以下であることが有利に適合する。
【００１２】
【発明の実施の形態】以下、本発明の解明経緯について説明する。
前述したとおり、バインダーとして金属相を用いた場合には、中性子増倍効果の低下など金属間化合物の特性劣化が生じる。
そこで、発明者らは、金属相に代わるバインダーとして種々の材料の組合せ実験を行っていたところ、かようなバインダーとして別種の材料を用いなくても、特定組成のベリリウム金属間化合物同士を組み合わせることによって、延性の改善に関し、望外の成果を得ることができた。
すなわち、Ｂｅ１２ＴｉとＢｅ１７Ｔｉ２とが混在する比率でベリリウムとチタンを混合し、これを鋳造してその延性を調べたところ、Ｂｅ１２ＴｉやＢｅ１７Ｔｉ２単味の場合に比べて、延性が格段に向上することが究明されたのである。
【００１３】ここに、上記したＢｅ１２ＴｉとＢｅ１７Ｔｉ２の配合比率については特に制限されず、一方が僅かでも混在していると、その分、延性が向上することが判明したが、特に好ましくはＢｅ１２ＴｉとＢｅ１７Ｔｉ２の比が１：０．５〜２．０の場合、Ｂｅ−ｘａｔ％Ｔｉで示すとｘが８．８〜９．９ａｔ％の場合にとりわけ良好な結果が得られることが判明した。
【００１４】次に、発明者らは、Ｔｉ以外の成分についても、同様な効果が得られるのではないかと考え、種々の成分についても検討した結果、Ｖ，Ｍｏ，Ｗ，Ｚｒ，ＮｂおよびＴａが、Ｔｉと同様な効果があることが判明した。
そして、これらの元素を用いる場合も、Ｔｉの場合と同様、Ｂｅ１２ＭおよびＢｅ１７Ｍ２（但し、ＭはＶ，Ｍｏ，Ｗ， ＮｂおよびＴａのうちから選んだいずれか一種）で示されるベリリウム金属間化合物（特にＭがＺｒの場合は、Ｂｅ１３ＺｒとＢｅ１７Ｚｒ２で示されるベリリウム金属間化合物）が混在する比率とすれば良いことが究明された。
【００１５】さらに、かようなベリリウム金属間化合物の複合相の組織については、鋳造組織で、しかもその結晶粒径を５０μｍ 以下とくに好ましくは２０μｍ 以下とすることが、強度をはじめとして、延性の面で一層有利であることが判明した。
【００１６】なお、本発明に従う中性子増倍材微小球の大きさは、平均粒径で０．１〜３．０ ｍｍ程度とすることが望ましい。またその真球度は、粒径×０．５ ｍｍ以下とすることが好ましい。
さらに、中性子増倍材中のＦｅ濃度は０．４ｍａｓｓ％以下程度、また酸化物の混入量は５．０ ｍａｓｓ％以下程度とすることが有利である。
【００１７】次に、本発明に従う中性子増倍材の製造方法について説明する。本発明では、中性子増倍材の製造方法を特に限定することはないが、従来から公知の回転電極法や粉末冶金法が特に有利に適合する。
・回転電極法
回転電極法によって本発明の中性子増倍材微小球を製造するには、まず消耗電極を作製する必要がある。この消耗電極を作製するには、所望の金属間化合物の組成比率となるようにベリリウムと各種金属とを混ぜ、これらを溶解し、鋳造したのち、所定の電極形状に機械加工する。
ついで、得られた消耗電極を用い、回転電極法によって、中性子増倍材微小球を製造する。
なお、この際の製造条件は特に限定されることはないが、好適条件について述べると次のとおりである。
・雰囲気ガス圧：５００〜１２０００ Ｔｏｒｒ
・アーク電流：１００〜１０００Ａ
・消耗電極の回転速度：４〜１０００ ｍ／ｓ
【００１８】・粉末冶金法
この方法によって中性子増倍材微小球を製造するには、所望の金属間化合物の組成比率となるようにベリリウムと各種金属とを混ぜ、これらを溶解し、鋳造したのち、粉砕し、得られた粉末を球形の金型等に装填し、冷間プレス等で球形に圧粉成形したのち、真空雰囲気中で焼結して微小球とする。
【００１９】
【実施例】表１に示す組成になるベリリウム金属間化合物の複合相からなる中性子増倍材を、回転電極法または粉末冶金法によって製造した。なお、得られた中性子増倍材の粒径は０．７〜１．３ ｍｍである。
かくして得られた各中性子増倍材の中性子増倍効果、耐スエリング性、延性、構造材との反応性、蒸気との反応性、トリチウムインベントリおよび熱伝導率について調べた結果を、表２に示す。
【００２０】なお、各特性は次のようにして評価した。
・中性子増倍効果
中性子増倍効果は、構成元素の持つ中性子反応断面積、中性子吸収断面積および中性子捕獲断面積の値を考慮して、従来の金属ベリリウム微小球を用いた場合の中性子増倍効果を １．０とし、それとの相対比で評価した。
・耐スエリング性
７００℃で、材料中に生成するＨｅ量が４０００ｐｐｍとなる中性子照射条件において、スエリング量を判断するものとし、スエリングの程度に応じ、小（スエリング量：０．５ ｖｏｌ％以下）、中（スエリング量：０．５ ｖｏｌ％超、３．０ ｖｏｌ％以下）、大（スエリング量：３．０ ｖｏｌ％超）で評価した。なお、スエリング量は体積変化率（ΔＶ／Ｖ×１００（％））で求めた。
・延性
室温において、直径が約１ｍｍφの微小球に対し、圧縮速度：０．２ ｍｍ／ｍｉｎの条件で圧縮試験を行い、かかる圧縮試験後の形態によって評価した。
【００２１】・構造材との反応性
６ＮのＨｅ雰囲気中にて、ステンレス鋼を、８００〜１０００ｈの反応性試験に供し、その際の構造材との反応の程度に応じ、小（反応層：５０μｍ 以下）、中（反応層：５０μｍ 超、２００μｍ 以下）、大（反応層：２００μｍ 超）で評価した。
・蒸気との反応性
８００℃において、水蒸気との反応試験を行い、その際の水蒸気との反応の程度に応じ、小（ほとんど酸化しない）、中（酸化する）、大（酸化により破壊する）で評価した。
・トリチウムインベントリ
スエリングの実験を行った試料について、昇温脱離法により測定したトリチウム量でトリチウムインベントリを評価した。すなわち、トリチウムインベントリの程度に応じ、小（極めて少ない）、中（幾分生じる）、大（かなり生じる）で評価した。
【００２２】
【表１】
【表２】
これに対し、Ｎｏ．３１の比較例は、Ｂｅ１２Ｔｉ単味であるため、延性に乏しい。
また、Ｎｏ．３２の比較例は、ベリリウム金属間化合物相間にバインダーとして金属相が介在しているため、延性や耐スエリング性に優れ、またトリチウムインベントリが小さく、構造材との反応性および蒸気との反応性も低いけれども、中性子増倍効果に劣っている。
さらに、Ｎｏ．３３の従来例は、金属ベリリウムが１００％であるため、中性子増倍効果や延性には優れるものの、スエリングやトリチウムインベントリが大きく、また構造材との反応性および蒸気との反応性も大きい。
【００２５】
【発明の効果】かくして、本発明によれば、高温での特性に優れるのは言うまでもなく、加工性が良好で歩留りや生産性に優れ、さらには取り扱いも極めて容易な、核融合炉用中性子増倍材を安定して得ることができる。[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutron multiplier for a fusion reactor having excellent high temperature characteristics and ductility.
[0002]
Conventionally, beryllium microspheres have been the standard material for neutron multipliers for fusion reactors. This is because the metal beryllium microspheres have a large neutron reaction cross section and are excellent in neutron multiplication effects that increase the number of neutrons. This is because it is possible to grow tritium, which is an advantage, and an advantageous improvement of the fusion fuel cycle can be expected.
However, in recent years, in order to increase the power generation efficiency of the nuclear fusion reactor and extend the lifetime, the neutron multiplier is used at a higher temperature (600 to 900 ° C.) and in a higher neutron irradiation environment (up to 20000 appmHe). Plans to use are in progress.
However, although the above-mentioned metal beryllium has no problem under the conventional use environment, various problems have been addressed when used at higher temperatures.
That is, metal beryllium has no problem as a neutron multiplier for a fusion reactor in a conventionally considered use temperature up to about 400 ° C., and neutron irradiation environment up to about 3000 appmHe. If it exceeds ℃, it will be oxidized by high-temperature steam at the time of an accident such as breakage of the cooling pipe to generate hydrogen, increasing the danger of hydrogen explosion, etc., and swelling may occur, causing damage to the container, It may not be used as a neutron multiplier for such high temperature power generation blankets.
Therefore, development of neutron multipliers that can be used at high temperatures is currently underway.
As a neutron multiplier that can be used at such a high temperature, beryllium intermetallic compounds are attracting attention.
For example, Be 12 Ti, which is one of beryllium intermetallic compounds, does not oxidize even when in contact with steam at 600 ° C., and hardly reacts at 600 ° C. in a compatibility test with SUS316LN, which is a blanket structure material. Furthermore, the reaction layer thickness at 800 ° C. is about 1/10 of that of metal beryllium, which has been found to be extremely chemically stable. In addition, it has been elucidated that the amount of swelling of Be 12 Ti is much smaller than that of metal beryllium from the results of investigation on swelling characteristics in the neutron irradiation test.
Thus, it has become clear that beryllium intermetallic compounds have excellent properties as neutron multipliers at high temperatures.
However, since beryllium intermetallic compounds are brittle at room temperature, they still have problems where their processing and handling are extremely difficult.
In other words, defects such as chips are likely to occur during machining, and yield and productivity must be reduced, and handling with great care is necessary so that cracks do not occur even after microspheres are formed. Therefore, its actual use was in danger.
By the way, the inventors previously developed a neutron multiplier for a fusion reactor comprising a composite phase of at least one beryllium intermetallic compound phase and a metal phase, as a solution to the above problem. This is disclosed in Japanese Patent Application No. 2002-105742.
According to the above technology, since the metal phase intervenes as a binder between the beryllium intermetallic compound phase, the adhesion strength between the beryllium intermetallic compound phases increases, as a result, the ductility of the entire neutron multiplier is improved, An advantageous improvement in workability and handling can be achieved.
[0008]
However, in the above technique, characteristic deterioration due to the interposition of the metal phase cannot be avoided. In other words, if a metal phase is interposed, the neutron multiplication effect is reduced by that amount, as well as swelling properties, reactivity with structural materials, reactivity with steam, and intermetallic compounds such as tritium inventory. The characteristic deterioration occurs.
Even if metal beryllium is used as the metal phase, the characteristic deterioration of the intermetallic compound similar to that described above occurs due to the αBe phase.
The present invention advantageously solves the above-mentioned problems, and for a fusion reactor excellent in high temperature characteristics and ductility, in which ductility is advantageously improved only by a beryllium intermetallic compound phase without the need for a metal phase as a binder. The purpose is to propose a neutron multiplier.
[0009]
Means for Solving the Problems Now, the inventors have conducted extensive research to solve the above problems, and as a result, compared to the case where a simple beryllium intermetallic compound is used, beryllium having a specific composition ratio is obtained. The knowledge that ductility is advantageously improved when intermetallic compounds are combined was obtained.
The present invention is derived from the above findings.
That is, the present invention
Chemical formula: Be-xat% M
However, M is one kind selected from Ti, V, Mo, W, Zr, Nb and Ta 7.7 <x <10.5 (at%)
A neutron multiplier for a nuclear fusion reactor excellent in high temperature characteristics and ductility, characterized by comprising a composite phase of Be 12 M or a beryllium intermetallic compound of Be 13 M and Be 17 M 2 represented by:
[0011]
In the present invention, the structure of the neutron multiplier is advantageously adapted to be a cast structure and a crystal grain size of 50 μm or less.
[0012]
DESCRIPTION OF THE PREFERRED EMBODIMENTS The elucidation process of the present invention will be described below.
As described above, when a metal phase is used as the binder, characteristic deterioration of the intermetallic compound such as a decrease in the neutron multiplication effect occurs.
Therefore, the inventors have conducted a combination experiment of various materials as a binder in place of the metal phase, and it is possible to combine beryllium intermetallic compounds having a specific composition without using another kind of material as such a binder. As a result, it was possible to obtain an unexpected result regarding the improvement of ductility.
That is, when beryllium and titanium were mixed at a ratio in which Be 12 Ti and Be 17 Ti 2 were mixed, and this was cast and its ductility was examined, it was compared with the case of Be 12 Ti or Be 17 Ti 2 plain. It has been determined that the ductility is remarkably improved.
Here, the blending ratio of the above Be 12 Ti and Be 17 Ti 2 is not particularly limited, and it has been found that if only one of them is mixed, the ductility is improved accordingly. Preferably, when the ratio of Be 12 Ti to Be 17 Ti 2 is 1: 0.5 to 2.0, particularly good results when x is 8.8 to 9.9 at% as represented by Be-xat% Ti Was found to be obtained.
Next, the inventors thought that the same effect could be obtained with components other than Ti, and as a result of examining various components, V, Mo, W, Zr, Nb, and Ta. However, it turned out that there exists an effect similar to Ti.
When these elements are used, they are represented by Be 12 M and Be 17 M 2 (where M is any one selected from V, Mo, W, Nb and Ta), as in the case of Ti. It has been determined that the ratio of beryllium intermetallic compounds (especially beryllium intermetallic compounds represented by Be 13 Zr and Be 17 Zr 2 when M is Zr) may be used.
Furthermore, the structure of the composite phase of such beryllium intermetallic compound is a cast structure, and its crystal grain size is preferably 50 μm or less, particularly preferably 20 μm or less, in terms of strength and ductility. Was found to be more advantageous.
The size of the neutron multiplier microspheres according to the present invention is preferably about 0.1 to 3.0 mm in average particle size. Moreover, it is preferable that the sphericity is a particle size x 0.5 mm or less.
Further, it is advantageous that the Fe concentration in the neutron multiplier is about 0.4 mass% or less, and the amount of oxide mixed is about 5.0 mass% or less.
Next, a method for producing a neutron multiplier according to the present invention will be described. In the present invention, the production method of the neutron multiplier is not particularly limited, but the conventionally known rotating electrode method and powder metallurgy method are particularly advantageously adapted.
-Rotating electrode method In order to produce the neutron multiplier microsphere of the present invention by the rotating electrode method, it is necessary to first produce a consumable electrode. In order to produce this consumable electrode, beryllium and various metals are mixed so that the composition ratio of a desired intermetallic compound is obtained, these are dissolved, cast, and then machined into a predetermined electrode shape.
Next, neutron multiplier microspheres are produced by the rotating electrode method using the obtained consumable electrode.
In addition, although the manufacturing conditions in this case are not specifically limited, It is as follows when a suitable condition is described.
-Atmospheric gas pressure: 500-12000 Torr
・ Arc current: 100-1000A
・ Rotating speed of consumable electrode: 4 to 1000 m / s
Powder metallurgy method In order to produce neutron multiplier microspheres by this method, beryllium and various metals are mixed so that the composition ratio of the desired intermetallic compound is obtained, and these are melted and cast. The powder obtained is pulverized, loaded into a spherical mold or the like, compacted into a spherical shape by a cold press or the like, and then sintered in a vacuum atmosphere to form microspheres.
[0019]
EXAMPLE A neutron multiplier comprising a composite phase of beryllium intermetallic compounds having the composition shown in Table 1 was produced by the rotating electrode method or the powder metallurgy method. The particle size of the obtained neutron multiplier is 0.7 to 1.3 mm.
Table 2 shows the neutron multiplication effect, swelling resistance, ductility, reactivity with structural materials, reactivity with steam, tritium inventory and thermal conductivity of each neutron multiplier thus obtained. .
Each characteristic was evaluated as follows.
Neutron multiplication effect The neutron multiplication effect takes into account the values of the neutron reaction cross section, neutron absorption cross section and neutron capture cross section of the constituent elements, and neutron multiplication using conventional metal beryllium microspheres. The effect was set to 1.0, and the evaluation was made based on the relative ratio.
・ Swelling resistance Under the neutron irradiation condition where the amount of He produced in the material is 4000 ppm at a temperature of 700 ° C., the amount of swelling is judged, and depending on the degree of swelling, the amount is small (swelling amount: 0.5 vol% or less) , Medium (swelling amount: more than 0.5 vol%, 3.0 vol% or less) and large (swelling amount: more than 3.0 vol%). In addition, the amount of swelling was calculated | required by the volume change rate ((DELTA) V / V * 100 (%)).
A compression test was performed on a microsphere having a diameter of about 1 mmφ at a ductile room temperature under the condition of a compression speed of 0.2 mm / min, and the evaluation was performed according to the form after the compression test.
Reactivity with structural material In a 6N He atmosphere, stainless steel is subjected to a reactivity test of 800 to 1000 h, and depending on the degree of reaction with the structural material at that time (reaction layer: 50 μm or less), middle (reaction layer: more than 50 μm, 200 μm or less), and large (reaction layer: more than 200 μm).
・ Reactivity with steam At 800 ° C, a reaction test with water vapor was conducted, and depending on the degree of reaction with water vapor at that time, small (nearly oxidized), medium (oxidized), large (destructed by oxidation) It was evaluated with.
-The tritium inventory was evaluated by the tritium amount measured by the temperature programmed desorption method for the samples on which the tritium inventory swelling experiment was conducted. That is, depending on the degree of tritium inventory, the evaluation was small (very little), medium (somewhat occurs), and large (very much).
[0022]
[Table 1]
[Table 2]
In contrast, no. Since the comparative example of 31 is Be 12 Ti simple, it has poor ductility.
No. In Comparative Example 32, a metal phase is interposed as a binder between the beryllium intermetallic compound phases, so that the ductility and swelling resistance are excellent, the tritium inventory is small, the reactivity with the structural material and the reactivity with the vapor are also achieved. Although it is low, it is inferior to the neutron multiplication effect.
Furthermore, no. In the conventional example of 33, metal beryllium is 100%, so that the neutron multiplication effect and ductility are excellent, but swelling and tritium inventory are large, and the reactivity with the structural material and the reactivity with the vapor are also large.
[0025]
Thus, according to the present invention, it is needless to say that the characteristics at high temperature are excellent, and the neutron gain for a fusion reactor is excellent, which is excellent in workability, excellent in yield and productivity, and extremely easy to handle. A double material can be obtained stably.
Claims (2)
但し、Ｍは、Ｔｉ，Ｖ，Ｍｏ，Ｗ，Ｚｒ，ＮｂおよびＴａのうちから選んだいずれか一種
７．７＜ｘ＜１０．５（ａｔ％）
で表わされる、Ｂｅ１２ＭまたはＢｅ１３ＭとＢｅ１７Ｍ２とのベリリウム金属間化合物の複合相からなることを特徴とする高温特性および延性に優れた核融合炉用中性子増倍材。Chemical formula: Be-xat% M
However, M is one kind selected from Ti, V, Mo, W, Zr, Nb and Ta 7.7 <x <10.5 (at%)
A neutron multiplier for fusion reactors having excellent high-temperature characteristics and ductility, characterized by comprising a composite phase of Be 12 M or a beryllium intermetallic compound of Be 13 M and Be 17 M 2 represented by:
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| JP2002253284A JP3882114B2 (en) | 2002-08-30 | 2002-08-30 | Neutron multiplier for fusion reactor |
| PCT/JP2003/004462 WO2003085678A1 (en) | 2002-04-08 | 2003-04-08 | Material for nuclear fusion furnace excellent in high temperature characteristics comprising beryllium intermetallic compound |
| EP03745972.4A EP1494244B1 (en) | 2002-04-08 | 2003-04-08 | Material for nuclear fusion reactor excellent in high temperature characteristics comprising beryllium intermetallic compound |
| US10/954,958 US7560069B2 (en) | 2002-04-08 | 2004-09-30 | Material including beryllium intermetallic compound and having excellent high-temperature property applied to nuclear fusion reactor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010019608A (en) * | 2008-07-08 | 2010-01-28 | Japan Atomic Energy Agency | Beryllium material filling body, and molding method of beryllium material filling body |
| JP2013209694A (en) * | 2012-03-30 | 2013-10-10 | Japan Atomic Energy Agency | Apparatus for producing beryllide pebble |
| CN116121613A (en) * | 2022-12-21 | 2023-05-16 | 北京科技大学 | Beryllium-zirconium alloy and application thereof in nuclear fusion |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010019608A (en) * | 2008-07-08 | 2010-01-28 | Japan Atomic Energy Agency | Beryllium material filling body, and molding method of beryllium material filling body |
| JP2013209694A (en) * | 2012-03-30 | 2013-10-10 | Japan Atomic Energy Agency | Apparatus for producing beryllide pebble |
| CN116121613A (en) * | 2022-12-21 | 2023-05-16 | 北京科技大学 | Beryllium-zirconium alloy and application thereof in nuclear fusion |
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