JP2006028580A - Powder for measuring flow velocity of lead-bismuth melt, ultrasonic flow velocity measuring method using the same and liquid target system for nuclear spallation neutron source - Google Patents
Powder for measuring flow velocity of lead-bismuth melt, ultrasonic flow velocity measuring method using the same and liquid target system for nuclear spallation neutron source Download PDFInfo
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- 229910052797 bismuth Inorganic materials 0.000 title claims abstract description 98
- 239000000843 powder Substances 0.000 title claims abstract description 81
- 238000000034 method Methods 0.000 title claims abstract description 26
- 239000007788 liquid Substances 0.000 title claims description 35
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims abstract description 28
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 27
- 239000010937 tungsten Substances 0.000 claims abstract description 27
- MGRWKWACZDFZJT-UHFFFAOYSA-N molybdenum tungsten Chemical compound [Mo].[W] MGRWKWACZDFZJT-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910001182 Mo alloy Inorganic materials 0.000 claims abstract description 16
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims description 86
- 238000005259 measurement Methods 0.000 claims description 44
- 239000002245 particle Substances 0.000 claims description 26
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 20
- 229910052750 molybdenum Inorganic materials 0.000 claims description 17
- 239000011733 molybdenum Substances 0.000 claims description 17
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 14
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- 229910052760 oxygen Inorganic materials 0.000 claims description 14
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- 229910001338 liquidmetal Inorganic materials 0.000 description 8
- 238000002844 melting Methods 0.000 description 8
- 230000008018 melting Effects 0.000 description 8
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 8
- 229910052753 mercury Inorganic materials 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 238000001816 cooling Methods 0.000 description 6
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 239000000654 additive Substances 0.000 description 4
- 230000000996 additive effect Effects 0.000 description 4
- 238000005275 alloying Methods 0.000 description 4
- 239000002826 coolant Substances 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000003628 erosive effect Effects 0.000 description 3
- 239000006023 eutectic alloy Substances 0.000 description 3
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- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 238000005498 polishing Methods 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 229910052715 tantalum Inorganic materials 0.000 description 3
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 229910016523 CuKa Inorganic materials 0.000 description 2
- XLYOFNOQVPJJNP-ZSJDYOACSA-N Heavy water Chemical compound [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 2
- 229910000909 Lead-bismuth eutectic Inorganic materials 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
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- 229910052742 iron Inorganic materials 0.000 description 2
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- 239000000155 melt Substances 0.000 description 2
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- 239000002893 slag Substances 0.000 description 2
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- 239000002699 waste material Substances 0.000 description 2
- ABEXEQSGABRUHS-UHFFFAOYSA-N 16-methylheptadecyl 16-methylheptadecanoate Chemical compound CC(C)CCCCCCCCCCCCCCCOC(=O)CCCCCCCCCCCCCCC(C)C ABEXEQSGABRUHS-UHFFFAOYSA-N 0.000 description 1
- 238000007088 Archimedes method Methods 0.000 description 1
- 229910001152 Bi alloy Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 241000764238 Isis Species 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
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- 150000001621 bismuth Chemical class 0.000 description 1
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- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
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- 238000000227 grinding Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 238000005417 image-selected in vivo spectroscopy Methods 0.000 description 1
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- 229910000464 lead oxide Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000001683 neutron diffraction Methods 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 230000005658 nuclear physics Effects 0.000 description 1
- YEXPOXQUZXUXJW-UHFFFAOYSA-N oxolead Chemical compound [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
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- 238000007873 sieving Methods 0.000 description 1
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- 238000004544 sputter deposition Methods 0.000 description 1
- 238000005477 sputtering target Methods 0.000 description 1
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- 229910052719 titanium Inorganic materials 0.000 description 1
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- 238000012546 transfer Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Classifications
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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
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- Monitoring And Testing Of Nuclear Reactors (AREA)
- Particle Accelerators (AREA)
- Powder Metallurgy (AREA)
Abstract
Description
本発明は、高エネルギーの陽子ビームを鉛ビスマスに入射して、核破砕反応により高強度の中性子を発生させるとともに鉛ビスマスを熱媒体として利用する中性子源用液体金属ターゲット、および冷却材として利用する原子炉内のその流速測定技術に関する。 The present invention applies a high-energy proton beam to lead bismuth to generate high-intensity neutrons by a spallation reaction, and uses the liquid metal target for a neutron source that uses lead bismuth as a heat medium, and as a coolant. It relates to the flow velocity measurement technique in the nuclear reactor.
タングステン、モリブデンは高融点、高硬度などの特質から様々な耐熱性を利用した用途に用いられてきた。それら金属を合金化したタングステンモリブデン合金の活用は、特許文献１ではタングステンモリブデン合金を配線に用いることや特許文献２では配線を形成するためのスパッタリングターゲット技術が開示されている。これらは低抵抗、耐エッチング性および他配線との低コンタクト抵抗という特質を利用して、塊状または配線の材料としての利用および製作を試みている。 Tungsten and molybdenum have been used for various heat resistance applications due to their high melting point and high hardness. As for utilization of tungsten-molybdenum alloy obtained by alloying these metals, Patent Document 1 discloses the use of a tungsten-molybdenum alloy for wiring, and Patent Document 2 discloses a sputtering target technique for forming a wiring. These have attempted to be used and manufactured as a mass or wiring material by utilizing the characteristics of low resistance, etching resistance and low contact resistance with other wiring.
また、特許文献３ではヒーター、ランプに用いられる、タングステン粉末およびモリブデン粉末に酸化物を添加したタングステンモリブデン合金が開示されている。この特許文献３に開示された発明の場合には、タングステンに比較して、室温での電気抵抗が高く、高温に加熱した後も柔軟性を有するなどの特徴を生かしてタングステンモリブデン以外の添加物の導入によりヒーターとしての特性を向上しようとするものである。 Patent Document 3 discloses a tungsten-molybdenum alloy in which an oxide is added to tungsten powder and molybdenum powder, which are used for heaters and lamps. In the case of the invention disclosed in this Patent Document 3, an additive other than tungsten molybdenum is used by taking advantage of its features such as higher electrical resistance at room temperature and flexibility after heating to a higher temperature than tungsten. It is intended to improve the characteristics as a heater through the introduction of.
また、特許文献４には、タングステン及び／又はモリブデンと、鉄、コバルト、ニッケル及び銅の中から選択される少なくとも１種の遷移金属と、場所によってはすくなくとも１種の添加剤とから本質的に成り、鉄の含有量が金属の全重量に対して５０重量％未満であり且つ添加剤全体の含有量が金属の全重量に対して３重量％未満であるプレアロイ粉末であって、走査電子顕微鏡で測定した基本粒子の大きさが２００ｎｍよりも大きく且つ５μｍ以下であるプレアロイ金属粉末が開示されている。この特許文献４に記載された発明ではタングステンの焼結性を向上するための添加物組成を検討したものである。 Patent Document 4 essentially includes tungsten and / or molybdenum, at least one transition metal selected from iron, cobalt, nickel, and copper, and at least one additive depending on the location. A pre-alloy powder comprising an iron content of less than 50% by weight relative to the total weight of the metal and a total additive content of less than 3% by weight based on the total weight of the metal, the scanning electron microscope Discloses a prealloy metal powder having a basic particle size of greater than 200 nm and less than or equal to 5 μm as measured in. In the invention described in Patent Document 4, an additive composition for improving the sinterability of tungsten is examined.
高エネルギーの陽子ビームを重金属ターゲットに入射して、核破砕反応により高強度の中性子を発生させる中性子発生装置は、入射エネルギーに対して最も多くの中性子を発生させることができ、原子炉に比較して設備が簡素である。現在はタングステンやタンタル等で作製されたターゲットが水冷しながら使用されており、陽子とターゲット物質との核破砕反応により多数の高エネルギー中性子を発生させている。発生した高エネルギー中性子は、液体水素や重水でできた減速器で熱中性子や冷中性子に減速され、中性子ビーム輸送系を介して利用実験室に供給され中性子回折等の実験に利用されている。中性子を利用する生命科学、物質・材料研究、核物理、医療など多分野での利用がなされ、例えば英国ラザフォードアップルトン研究所の核破砕中性子線源ＩＳＩＳでは、８００ＭｅＶの陽子、２．５×１０１３個からなるパルスビームを５０Ｈｚの周期で、水冷されたタンタル製ターゲットに打ち込むことにより約１０１５個ｃｍ２ｓの中性子束を得ている。すなわち、１６０ｋｗの陽子ビームで約１０１５個ｃｍ２ｓの中性子線束を得ている。 A neutron generator that injects a high-energy proton beam into a heavy metal target and generates high-intensity neutrons by a spallation reaction can generate the largest number of neutrons relative to the incident energy, compared to a nuclear reactor. The equipment is simple. At present, targets made of tungsten, tantalum, or the like are used while being water-cooled, and a large number of high-energy neutrons are generated by a spallation reaction between protons and the target material. The generated high-energy neutrons are decelerated to thermal neutrons and cold neutrons by a decelerator made of liquid hydrogen or heavy water, supplied to a utilization laboratory through a neutron beam transport system, and used for experiments such as neutron diffraction. It is used in various fields such as life science using neutrons, material / material research, nuclear physics, and medical care. For example, in the spallation neutron source ISIS of Rutherford Appleton Laboratory in the UK, 800 MeV protons, 2.5 × 10 A neutron flux of about 10 15 cm 2 s is obtained by implanting 13 pulse beams into a water-cooled tantalum target at a frequency of 50 Hz. That is, a neutron flux of about 10 15 cm 2 s is obtained with a 160 kw proton beam.
近年、中性子線利用研究の重要性が急速に増加しつつあり、次世代核破砕中性子線源の計画が米国（ＳＮＳ計画）、日本（高エネ機構−原研統合計画）、ＥＣ（ＥＳＳ計画）で進められている。これら世界の３大計画は、いずれも１０１７個／ｃｍ２ｓ程度の中性子束を得るため、いまだ経験したことのないＭＷの陽子ビームをターゲットに入射させる予定で、ここでの陽子のエネルギーは１〜３ＧｅＶである。一般にＭＷ級ビームのターゲットは、ターゲット内の発熱が数百ｋＷに達するため、固体金属を水冷する現行の方式よりも、水銀ターゲット方式を採用しようと計画している。 In recent years, the importance of neutron beam research has been increasing rapidly, and plans for next-generation spallation neutron sources are in the United States (SNS project), Japan (High Energy Agency-JAERI Integrated Project), and EC (ESS project). It is being advanced. The three major plans in the world are all going to inject a proton beam of MW that has not yet been experienced in order to obtain a neutron flux of about 10 17 / cm 2 s. The proton energy here is 1 to 3 GeV. In general, a target of an MW class beam has a plan to adopt a mercury target method rather than the current method of cooling a solid metal with water because the heat generated in the target reaches several hundred kW.
公知の文献としては、特許文献５に、「液体ターゲットおよび中性子発生設備」として液体ターゲットの構造、特許文献６に、「核破砕中性子線源用水銀ターゲット構造」として液体水銀ターゲットの流路や構造、特許文献７に、「液体金属ターゲットシステム」として液体ターゲットシステムに酸素濃度制御系統を接続するシステム、特許文献８に、「中性子発生装置」として液体ターゲットのヒートサイフォンを形成する構造、特許文献９に、「中性子源用液体金属ターゲット」として特許文献６の発明を改良した構造が開示されている。これらはいずれも液体水銀を念頭に中性子線ターゲットを開発しているだけでなく、流速測定の重要性についても検討がなされていない。もちろん本発明とは目的が異なる。 As known documents, Patent Document 5 describes the structure of a liquid target as “liquid target and neutron generation facility”, and Patent Document 6 describes the flow path and structure of a liquid mercury target as “mercury target structure for spallation neutron source”. Patent Document 7 discloses a system that connects an oxygen concentration control system to a liquid target system as a “liquid metal target system”, Patent Document 8 discloses a structure that forms a heat siphon of a liquid target as a “neutron generator”, and Patent Document 9 The structure which improved the invention of patent document 6 as "a liquid metal target for neutron sources" is disclosed. Both of these have not only developed neutron targets with liquid mercury in mind, but the importance of velocity measurement has not been studied. Of course, the object is different from the present invention.
水銀ターゲットにおいてはその流速測定についての測定に関しての知見が公表されていないが、液体の流速を測定するための手段についてはいくつかの公知文献が存在する。例えば、特許文献１０および特許文献１１の「ドップラー式超音波流量／流速測定装置」として、液体の流速を測定する手段としてキャビテーションによる気泡の発生やヒーターによる温度差を利用しての液体の流速測定方法が開示されているが、鉛ビスマスといった液体金属ではこれらの手段を適用することはできなかった。その他にも超音波で流速を測定する手段についての発明が種々あるが、液体金属への適用例はなく、液体金属の流速を測定できたとしても精度に問題があった。発明者らは液体と等速で移動する超音波反射材の開発こそが正確に流速を把握する手段であることを見出した。 In the mercury target, the knowledge about the measurement of the flow rate is not disclosed, but there are some known documents about the means for measuring the flow rate of the liquid. For example, as a “Doppler type ultrasonic flow rate / flow rate measuring device” in Patent Document 10 and Patent Document 11, a flow rate measurement of a liquid using a bubble generated by cavitation and a temperature difference by a heater as a means for measuring the flow rate of the liquid. Although a method is disclosed, these means cannot be applied to liquid metals such as lead bismuth. There are various other inventions concerning means for measuring the flow velocity with ultrasonic waves, but there is no application to liquid metal, and there was a problem in accuracy even if the flow velocity of liquid metal could be measured. The inventors have found that the development of an ultrasonic reflector that moves at the same speed as the liquid is the means for accurately grasping the flow velocity.
さらに、鉛ビスマスの合金だけに関して言えば、特許文献１２に、「鉛ビスマス共晶合金の純化方法および純化装置」が開示されているが、原子炉用冷却材としての鉛ビスマス共晶合金の純化を目的としているだけでなく、ここにも流速測定に関する知見はない。 Furthermore, as far as only the lead-bismuth alloy is concerned, Patent Document 12 discloses "Purification method and purification device for lead-bismuth eutectic alloy", but purification of lead-bismuth eutectic alloy as a coolant for nuclear reactors. There is no knowledge about the flow velocity measurement here.
次世代中性子源の次、言わば次次世代に考えられているのが、水銀ではなく鉛ビスマスをターゲットとし、１〜１．５ＧｅＶで２０〜３０ＭＷクラスの中性子源である。前述の次世代水銀ターゲットよりも１桁入力エネルギーＭＷが大きく、ターゲットへの入熱が大きい。水銀は沸点が低く気相発生による除熱性能の劣化が起こり易いため、取り扱いの容易性からもターゲットは鉛ビスマスが適している。 Next to the next generation neutron source, the next generation is considered to be a neutron source of 1 to 1.5 GeV and 20 to 30 MW class targeting lead bismuth instead of mercury. Single-digit input energy MW is larger than the next-generation mercury target, and heat input to the target is large. Mercury has a low boiling point and is likely to deteriorate the heat removal performance due to gas phase generation. Therefore, lead bismuth is suitable for the ease of handling.
さらに、鉛ビスマスを冷却材としても使用することが考えられている。鉛ビスマスターゲット・冷却材を用いた中性子源システムは、原子力エネルギーの利用の結果、燃料の廃棄物中に含まれる発生する核分裂生成物やマイナーアクニドを核変換してより短寿命の核種に変換し、環境及び子孫への負荷を減らそうとする狙いがある。そのときに使う中性子を鉛ビスマスの原子核を壊して生産する。つまりは、鉛ビスマスのターゲットから得られた中性子を、核廃棄物の半減期を短縮して環境影響を小さくするために変換する技術を確立しようとするものである。そのため、鉛ビスマス溶融液中で構造材との共存性など構造成立性を確保する制御技術が現在研究開発され習得しようとされている。構造成立性の一つに材料の腐食、エロージョン特性がある。エロージョンは鉛ビスマスの流れと密接な関係がある。すなわち、流れが乱れ、材料表面から流線が剥離するような場所でエロージョンが起こるとされている。従って、構造物周りでの流れの可視化が必要となる。もう一つは、伝熱特性が挙げられる。すなわち、陽子ビームが貫通する材料中に核破砕反応によって蓄積される熱を、鉛ビスマス流で除去する必要がある。最大の効率を持って熱を除去できる構造とするためには流れの可視化が必要となる。通常、流れの可視化は水、及び気体を持って行われるが、鉛ビスマスのように比重が１０．５ｇ／ｃｃの重い高温液体では、計算機によるシミュレーション結果を裏付ける実験が必要である。また、製作した機器の内部流れを検知したい場合も生じる。しかし、鉛ビスマスは光学的に不透明なため、流れの様子を知る手だてが超音波以外になく、鉛ビスマスを可視化（超音波流速を実測）する反射体粒子の開発が必須だとの結論に達した。 Furthermore, it is considered to use lead bismuth as a coolant. The neutron source system using lead bismuth target / coolant transforms the fission products and minor acnides generated in the fuel waste as a result of the use of nuclear energy into shorter-lived nuclides. However, there is an aim to reduce the burden on the environment and offspring. The neutrons used at that time are produced by breaking the lead bismuth nucleus. In other words, it is intended to establish a technology to convert neutrons obtained from a lead-bismuth target in order to reduce the environmental impact by reducing the half-life of nuclear waste. For this reason, a control technology that ensures structural feasibility such as coexistence with structural materials in lead bismuth melt is currently being researched and developed. One of the structural feasibility is material corrosion and erosion characteristics. Erosion is closely related to the flow of lead bismuth. That is, it is said that erosion occurs in a place where the flow is disturbed and the streamline is separated from the material surface. Therefore, it is necessary to visualize the flow around the structure. Another is heat transfer characteristics. That is, it is necessary to remove the heat accumulated by the spallation reaction in the material through which the proton beam penetrates with a lead bismuth flow. Visualization of the flow is necessary to achieve a structure that can remove heat with maximum efficiency. Usually, flow visualization is carried out with water and gas, but for a high-temperature liquid with a specific gravity of 10.5 g / cc, such as lead bismuth, an experiment to support the simulation results by a computer is necessary. There are also cases where it is desired to detect the internal flow of the manufactured device. However, since lead bismuth is optically opaque, it is concluded that there is no other way to know the flow state than ultrasonic waves, and it is essential to develop reflector particles that visualize lead bismuth (measurement of ultrasonic flow velocity). did.
そこで、本発明の技術的課題は、中性子源用の鉛ビスマス溶融液の流速を正確に測定するための超音波反射体として優れた特性を示すタングステンモリブデン合金粉末とその粉末を用いた鉛ビスマス溶融液流速測定方法とターゲットシステムとを提供することにある。 Therefore, the technical problem of the present invention is that tungsten molybdenum alloy powder exhibiting excellent characteristics as an ultrasonic reflector for accurately measuring the flow rate of a lead bismuth melt for a neutron source and lead bismuth melting using the powder. The object is to provide a liquid flow rate measuring method and a target system.
本発明によれば、タングステンを６〜４６質量％含み残部が実質的にモリブデンのタングステンモリブデン合金からなることを特徴とする鉛ビスマス溶融液流速測定用粉末が得られる。 According to the present invention, there can be obtained a lead-bismuth melt flow rate measuring powder characterized by comprising 6 to 46% by mass of tungsten and the balance being substantially made of tungsten molybdenum alloy of molybdenum.
また、本発明によれば、前記鉛ビスマス溶融液流速測定用粉末において、空孔率を１０％以下、密度を１０．５〜１３．０ｇ／ｃｍ３としたことを特徴とする鉛ビスマス溶融液流速測定用粉末が得られる。 Further, according to the present invention, in the lead bismuth melt flow rate measurement powder, the porosity is 10% or less and the density is 10.5 to 13.0 g / cm 3. A powder for flow rate measurement is obtained.
また、本発明によれば、前記鉛ビスマス溶融液流速測定用粉末において、粒子の大きさをＡとし、測定に使用する超音波の波長Ｂに対して、ＡはＢ／４−Ｂ／２０からＢ／４＋Ｂ／１０の範囲に９割以上の粒子が分布していることを特徴とする鉛ビスマス溶融液流速測定用粉末が得られる。 Further, according to the present invention, in the powder for measuring lead bismuth melt flow rate, the particle size is A, and A is from B / 4-B / 20 with respect to the wavelength B of the ultrasonic wave used for the measurement. A powder for measuring the flow rate of lead bismuth melt, characterized in that 90% or more of the particles are distributed in the range of B / 4 + B / 10, is obtained.
また、本発明によれば、前記鉛ビスマス溶融液流速測定用粉末において、酸素濃度を１００質量ｐｐｍ以下としたことを特徴とする鉛ビスマス溶融液流速測定用粉末が得られる。 Further, according to the present invention, the lead bismuth melt flow rate measuring powder characterized in that the oxygen concentration in the lead bismuth melt flow rate measuring powder is 100 mass ppm or less can be obtained.
また、本発明によれば、前記鉛ビスマス溶融液流速測定用粉末において、粉末表面をニッケルで被覆したことを特徴とする鉛ビスマス溶融液流速測定用粉末。 According to the present invention, the lead bismuth melt flow rate measuring powder according to the lead bismuth melt flow rate measuring powder, wherein the powder surface is coated with nickel.
また、本発明によれば、前記いずれか一つの鉛ビスマス溶融液流速測定用粉末を用いたことを特徴とする核破砕中性子源液体ターゲットシステムが得られる。 Further, according to the present invention, there is obtained a spallation neutron source liquid target system using any one of the lead bismuth melt flow velocity measurement powders.
また、本発明によれば、タングステンを６〜４６質量％含み残部が実質的にモリブデンからなる鉛ビスマス溶融液流速測定用粉末を媒体とし、鉛ビスマス溶融液流に超音波を流体の流れ方向に対して平行以外の方向で入射して、ドップラー効果により鉛ビスマス溶融液の流速を測定することを特徴とする超音波流速測定方法が得られる。 Further, according to the present invention, the powder for measuring the flow rate of lead bismuth melt consisting of 6 to 46% by mass of tungsten and the balance being substantially molybdenum is used as a medium, and ultrasonic waves are applied to the lead bismuth melt flow in the fluid flow direction. On the other hand, an ultrasonic flow velocity measuring method is obtained, which is incident in a direction other than parallel and measures the flow velocity of the lead bismuth melt by the Doppler effect.
また、本発明によれば、前記に記載の超音波流速測定方法を用いたことを特徴とする核破砕中性子源液体ターゲットシステムが得られる。 In addition, according to the present invention, a spallation neutron source liquid target system using the ultrasonic velocity measurement method described above is obtained.
以上説明したように、本発明によれば、中性子源用の鉛ビスマス溶融液の流速を正確に測定するための超音波反射体として優れた特性を示すタングステンモリブデン合金粉末を得ることができる。また、その粉末を用いたターゲットシステムを構築できる。 As described above, according to the present invention, it is possible to obtain a tungsten-molybdenum alloy powder exhibiting excellent characteristics as an ultrasonic reflector for accurately measuring the flow rate of a lead bismuth melt for a neutron source. Moreover, the target system using the powder can be constructed.
また、本発明においては中性子源用の鉛ビスマス溶融液を中心に記述したが、原子炉冷却用などとして鉛ビスマスを溶融する場合にも本発明の粉末を用いて同様の手法により流速測定を精密に行なうことができる。 Further, in the present invention, description has been made centering on lead bismuth melt for neutron sources. However, even when lead bismuth is melted for reactor cooling or the like, the flow rate is accurately measured by the same method using the powder of the present invention. Can be done.
本発明を更に詳細に説明する。 The present invention will be described in further detail.
本発明は、鉛ビスマス溶融液の中性子源ターゲットに関し、ターゲットシステムにとって重要な流速を明らかにするための手段を提供するものである。 The present invention relates to a neutron source target of a lead bismuth melt and provides a means for revealing the flow velocity important to the target system.
鉛ビスマスは、鉛とビスマスとの重量比率が４４．８（％）：５５．２（％）の共晶合金である。 Lead bismuth is a eutectic alloy in which the weight ratio of lead to bismuth is 44.8 (%): 55.2 (%).
図１は鉛ビスマスの二元系状態図である。また、この融点は１２５．５℃であるので、液体である金属としては、ナトリウムと同様な取り扱い技術を適用することが可能で、従来の液体金属技術を活用できるという利点がある。 FIG. 1 is a binary system phase diagram of lead bismuth. Moreover, since this melting | fusing point is 125.5 degreeC, the handling technique similar to sodium can be applied as a metal which is a liquid, and there exists an advantage that the conventional liquid metal technique can be utilized.
融点が９８℃のナトリウムは化学的に活性が高いことから、取り扱い時には空気中の水と反応して発火するのを防止するために、不活性雰囲気内で作業することが必要であったり、特別な設備対策などが必要であるばかりでなく、ナトリウム火災を引き起こす可能性もあるために、漏洩を防止する対策や防火対策も必要であることから比較すれば、液体金属としての取り扱いはナトリウムよりも遥かに容易である。 Sodium with a melting point of 98 ° C is chemically highly active, so it is necessary to work in an inert atmosphere to prevent it from igniting by reaction with water in the air during handling. Compared to the need for measures to prevent leakage and fire prevention measures because it may cause a sodium fire as well as necessary equipment measures, etc. Much easier.
目的や使用方法は異なるものの、先述の特許文献１２でも議論されているように、鉛ビスマスは使用環境により純度が劣化してその基本物性が損なわれたり、鉛が不純物と化合、固化することで共晶点に対する組成がずれて融点が上昇したり、粘度が変化する問題は本発明と共通のものである。液体ターゲットである鉛ビスマス溶融液中で新たな不純物となる材質の溶出や、粉末を投入することによる鉛ビスマスへの酸素の溶解があることは避けられなければならない。 Although the purpose and method of use are different, as discussed in the above-mentioned Patent Document 12, lead bismuth deteriorates in purity due to the use environment, its basic physical properties are impaired, or lead is combined with impurities and solidified. The problem that the composition with respect to the eutectic point is shifted and the melting point is increased or the viscosity is changed is common to the present invention. The elution of a material that becomes a new impurity in the lead bismuth melt, which is a liquid target, and the dissolution of oxygen in lead bismuth by introducing powder must be avoided.
そこで、後述するような予備試験、発明の実施の形態において実証した形のタングステンモリブデン合金を作製し活用することにより、液体ターゲットである鉛ビスマスを変質（不純物の導入、組成を変化）させることなく、また、確実かつ正確に流速を測定できることにより、核破砕中性子源液体ターゲットシステムを信頼性が高く、高度にコントロールされたシステムとすることができる。 Therefore, by preparing and utilizing a tungsten molybdenum alloy in the form demonstrated in the preliminary test and the embodiment of the invention as described later, lead bismuth which is a liquid target is not altered (introduction of impurities, change in composition). In addition, since the flow velocity can be measured reliably and accurately, the spallation neutron source liquid target system can be a highly reliable and highly controlled system.
ここで、鉛ビスマス溶融液の流速は液体ターゲットとしての温度維持、流動性維持のために非常に重要な因子であり、その正確な流速の測定およびそれをフィードバックした循環装置のコントロールは、ターゲットとしての特性を十分に発揮するために重要な項目である。 Here, the flow rate of the lead bismuth melt is a very important factor for maintaining the temperature and fluidity of the liquid target. Accurate measurement of the flow rate and control of the circulating device that feeds back the flow rate are important targets. It is an important item to fully demonstrate the characteristics of.
本発明に係るタングステンを６〜４６質量％含み残部が実質的にモリブデンからなるタングステンモリブデン合金粉末によれば、鉛ビスマス溶融液中で浮かびあがったまま、もしくは沈降したままにならず、鉛ビスマス溶融液と同一速度で流動する鉛ビスマス溶融液流速測定用粉末が得られる。 According to the tungsten-molybdenum alloy powder comprising 6 to 46% by mass of tungsten according to the present invention, with the balance being substantially molybdenum, the lead-bismuth melt does not remain floating or settled in the lead-bismuth melt. A powder for measuring the flow rate of lead bismuth melt flowing at the same speed as the liquid is obtained.
また、本発明に係る鉛ビスマス溶融液流速測定用粉末において、空孔率を１０％以下、密度を１０．５〜１３．０ｇ／ｃｍ３としている。本発明の鉛ビスマス溶融液流速測定用粉末によれば、鉛ビスマス溶融液中で浮かびあがったままや沈降したままにならず、鉛ビスマス溶融液と同一速度で流動し、速度誤差の少ない鉛ビスマス溶融液流速測定用粉末が得られる。 In the lead bismuth melt flow rate measurement powder according to the present invention, the porosity is 10% or less and the density is 10.5 to 13.0 g / cm 3 . According to the powder for measuring the flow rate of lead bismuth melt of the present invention, the lead bismuth that does not float or settle in the lead bismuth melt, flows at the same speed as the lead bismuth melt, and has a small speed error. A melt flow rate measurement powder is obtained.
また、本発明に係る鉛ビスマス溶融液流速測定用粉末において、粒子の大きさをＡとし、測定に使用する超音波の波長Ｂに対して、ＡはＢ／４−Ｂ／２０からＢ／４＋Ｂ／１０の範囲に９割以上の粒子が分布している。この本発明の粉末によれば、鉛ビスマス溶融液中での超音波流速測定に関し、安定して超音波による流速測定ができる粉末が得られる。 Further, in the powder for measuring the flow rate of lead bismuth melt according to the present invention, the particle size is A, and A is B / 4−B / 20 to B / 4 + B with respect to the ultrasonic wavelength B used for the measurement. More than 90% of the particles are distributed in the range of / 10. According to the powder of the present invention, it is possible to obtain a powder that can stably measure the flow velocity by ultrasonic waves with respect to the ultrasonic flow velocity measurement in the lead-bismuth melt.
本発明に係る鉛ビスマス溶融液流速測定用粉末において、酸素濃度を１００質量ｐｐｍ以下とした。この粉末によれば、余分な不純物であり、流れを乱すスラグの生成を極力抑える鉛ビスマス溶融液流速測定用粉末が得られる。 In the lead bismuth melt flow velocity measurement powder according to the present invention, the oxygen concentration was set to 100 mass ppm or less. According to this powder, a powder for measuring the flow rate of lead bismuth melt that suppresses the generation of slag that is an extra impurity and disturbs the flow as much as possible can be obtained.
本発明に係る鉛ビスマス溶融液流速測定用粉末において、粉末表面をニッケルで被覆した粉末によれば、表面凹凸を減少させ、鉛ビスマスとの濡れ性に優れる鉛ビスマス溶融液流速測定用粉末が得られる。 In the powder for measuring the flow rate of lead bismuth melt according to the present invention, the powder whose surface is coated with nickel reduces the surface irregularities and provides a powder for measuring the flow rate of lead bismuth melt with excellent wettability with lead bismuth. It is done.
本発明に係る粉末を用いた核破砕中性子源液体ターゲットシステムによれば、正確な鉛ビスマス溶融液流速測定により、長寿命で安定した核破砕中性子源液体ターゲットシステムの制御を行なうことが出来る。 According to the spallation neutron source liquid target system using the powder according to the present invention, it is possible to control a spallation neutron source liquid target system that is long-lived and stable by accurate lead bismuth melt flow velocity measurement.
本発明に係るタングステンを６〜４６質量％含み残部が実質的にモリブデンからなる鉛ビスマス溶融液流速測定用粉末を媒体とし、鉛ビスマス溶融液流に超音波を（流れに対して角度をつけて）入射して、ドップラー効果により鉛ビスマス溶融液の流速を測定する超音波流速測定方法によれば、反射体が溶融して反射特性を劣化させること無く良好な流速測定を行なうことができる。 The powder for measuring the flow rate of lead bismuth melt consisting of 6 to 46% by mass of tungsten according to the present invention, the balance being substantially molybdenum, is used as a medium, and ultrasonic waves are applied to the lead bismuth melt flow (at an angle to the flow). ) According to the ultrasonic flow velocity measuring method that enters and measures the flow velocity of the lead bismuth melt by the Doppler effect, a good flow velocity measurement can be performed without melting the reflector and deteriorating the reflection characteristics.
本発明に係る超音波流速測定方法を用いた核破砕中性子源液体ターゲットシステムによれば、装置およびシステムの制限が少なく、設計の自由度の大きな鉛ビスマス液体ターゲットシステムを得ることができる。 According to the spallation neutron source liquid target system using the ultrasonic flow velocity measuring method according to the present invention, it is possible to obtain a lead bismuth liquid target system with few apparatus and system limitations and a high degree of design freedom.
以下、本発明について更により具体的に説明する。 Hereinafter, the present invention will be described more specifically.
まず、鉛ビスマス溶融液のみでは液体金属であるが故に光学的に不透明であり速度測定を行なうことはできない。また、鉛ビスマス溶融液だけを媒体とする場合には超音波による反射が起こらず、ドップラー効果による測定を行なうことができない。 First, since lead bismuth melt alone is a liquid metal, it is optically opaque and speed measurement cannot be performed. Further, when only the lead bismuth melt is used as a medium, reflection by ultrasonic waves does not occur, and measurement by the Doppler effect cannot be performed.
ここで、まず鉛ビスマス溶融液中での化学的安定性を検討するために、１５０℃に加熱した鉛ビスマス溶融液に種々の粉末を投入し、それらが１００時間後に重量変化を起こすか、鉛ビスマス溶融液が変質や融点変化を起こす状況について確認した。平均粒径が各１０μｍの粉末で試験した結果、チタン、ニオブ、タンタル、モリブデン、タングステンなどの高融点金属が鉛ビスマスとの反応を起こしにくいことを確認した。これらの中で、タングステン、モリブデンを用いることが工業的に安価に製造でき、しかも鉛ビスマスの密度に近いために同一流速で流れる材質であることが予測できた。これらの知見に基づき、タングステン、モリブデンを合金化することにより所定の密度を予め計算して得ることを考えた。タングステンの密度１９．２ｇ／ｃｍ３（×１０３ｋｇ／ｍ３）、モリブデンの密度１０．２ｇ／ｃｍ３（×１０３ｋｇ／ｍ３）であり、これらを１ｃｍ３当たりの質量換算して計算を行なうことで、例えば、目的密度１０．５ｇ／ｃｍ３（×１０３ｋｇ／ｍ３）であれば原料のモリブデンとタングステンの質量比を９３．９：６．１とすれば良く、１０．９ｇ／ｃｍ３（×１０３ｋｇ／ｍ３）であれば原料のモリブデンとタングステンの質量比を８６．３：１３．７とすれば良いことが判った。さらに、合金化することで質量変化、つまりは鉛ビスマスとの反応も抑制され、１５０℃１００時間でモリブデン、タングステンではそれぞれ１％、０．５％であった重量変化が、合金化することにより０．１％未満になった。 Here, in order to examine the chemical stability in the lead bismuth melt, various powders are added to the lead bismuth melt heated to 150 ° C., and they change in weight after 100 hours. The situation in which the bismuth melt was altered and the melting point was changed was confirmed. As a result of testing with powders each having an average particle diameter of 10 μm, it was confirmed that refractory metals such as titanium, niobium, tantalum, molybdenum and tungsten hardly react with lead bismuth. Among these, it is possible to predict that the use of tungsten and molybdenum can be produced at low cost industrially and the material flows at the same flow rate because it is close to the density of lead bismuth. Based on these findings, it was considered that a predetermined density was calculated in advance by alloying tungsten and molybdenum. The density of tungsten is 19.2 g / cm 3 (× 10 3 kg / m 3 ), the density of molybdenum is 10.2 g / cm 3 (× 10 3 kg / m 3 ), and these are converted into mass per 1 cm 3. By performing the calculation, for example, if the target density is 10.5 g / cm 3 (× 10 3 kg / m 3 ), the mass ratio of the raw material molybdenum to tungsten may be 93.9: 6.1. It was found that the mass ratio of molybdenum and tungsten as a raw material should be 86.3: 13.7 if it is 9.9 g / cm 3 (× 10 3 kg / m 3 ). Furthermore, mass change, that is, reaction with lead bismuth is also suppressed by alloying, and weight changes that were 1% and 0.5% respectively for molybdenum and tungsten at 150 ° C. for 100 hours are caused by alloying. It became less than 0.1%.
ここで、本発明のタングステンモリブデン合金は、種々の条件を検討した結果、モリブデン粉末中にタングステン中間酸化物であるＷＯ２もしくはＷ１８Ｏ４９などの組成を混合し、大気圧水素中での７００〜１８００℃の１時間以上の還元処理、それに続く１０００〜２０００℃での１０−３Ｐａ真空中熱処理を５分以上行なうことにより、合金組成を形成し、例えばジョークラッシャーやハンマーミルなどによる粉砕により目的とする粉末を得ることが出来た。但し、原料粉末についてはタングステンを金属Ｗ粉末やＷＯ３とすることでも問題なく合金組成を得ることができた。また、水素中での熱処理のみで、真空中での熱処理を行なわずとも合金粉末を得ることができた。粉砕粉末は篩分によって任意の粒度の粉末を得ることができ、また、目的の粒度の粉末を得るためには熱処理温度を上記条件内にて制御することにより、任意の粒度を得ることができた。以上のような工程を選択することにより、工業的に容易に大量生産可能な工程を確立することができた。 Here, as for the tungsten molybdenum alloy of the present invention, as a result of examining various conditions, a composition such as WO 2 or W 18 O 49 , which is a tungsten intermediate oxide, is mixed in molybdenum powder, and 700 mol in atmospheric pressure hydrogen. 1800 1 hour or more reducing process ° C., by performing subsequent 1000 to 2000 ° C. in a 10 -3 Pa vacuum heat treatment of 5 minutes or more, to form an alloy composition, for example by milling due jaw crusher or hammer mill The target powder could be obtained. However, the raw material powder was able to obtain an alloy composition without problems by the tungsten metal W powder and WO 3. In addition, alloy powder could be obtained only by heat treatment in hydrogen and without heat treatment in vacuum. As for the pulverized powder, a powder having an arbitrary particle size can be obtained by sieving. In order to obtain a powder having a desired particle size, an arbitrary particle size can be obtained by controlling the heat treatment temperature within the above conditions. It was. By selecting the processes as described above, it was possible to establish a process that can be easily mass-produced industrially.
図２（ａ）は作製した粉末の電子顕微鏡写真（１００倍）、図２（ｂ）は図２（ａ）で示す粉末の拡大写真である（１０００倍）。図３はＸＲＤのデータを示す図である。 FIG. 2A is an electron micrograph (100 times) of the produced powder, and FIG. 2B is an enlarged photograph of the powder shown in FIG. 2A (1000 times). FIG. 3 is a diagram showing XRD data.
図３に示すように、タングステンが固溶していなければ１３１°にピークが現れるべきところであるが、タングステンピークは存在せず、タングステンモリブデンが完全に固溶した状態でＣｕＫα１およびＣｕＫα２のピークのみが確認できた。これらの粉末はＸＲＤによる測定により、タングステンとモリブデンのピークが分離していないため、完全に固溶していることが判った。また、粉末を埋め込み樹脂に混合し、研磨し電子顕微鏡で粉末断面のタングステン、モリブデンイメージを観察した結果からも、分散状態が均一であることを確認できた。その結果を図４に示す。 As shown in FIG. 3, but tungsten is where should peak appears in 131 ° if not dissolved, tungsten peak is absent, the peak of CuKa 1 and CuKa 2 in a state in which tungsten molybdenum has completely dissolved Only confirmed. As a result of XRD measurement, these powders were completely dissolved because the peaks of tungsten and molybdenum were not separated. Moreover, it was confirmed that the dispersion state was uniform from the result of mixing the powder with the embedding resin, polishing it, and observing the tungsten and molybdenum images of the powder cross section with an electron microscope. The result is shown in FIG.
図４（ａ）は粉末断面の電子顕微鏡写真（倍率１０００倍）、図４（ｂ）は図４（ａ）のタングステンのイメージを示す電子顕微鏡写真（倍率１０００倍）である。 4A is an electron micrograph (magnification 1000 times) of a powder cross section, and FIG. 4B is an electron micrograph (magnification 1000 times) showing an image of tungsten in FIG. 4A.
また、通常の製造方法では、製造されるモリブデン粉末の粒径を大きくするために、一旦粉末をプレス、焼結しスラグを作製したタングステンモリブデン合金を機械的な粉砕方法によって粗粒を得る方法が考えられる。その場合、本発明中で検討している空孔率は１０％を超え、例えば空孔率１５〜２０％になり、密度が１０．５ｇ／ｃｍ３を下回り実効的に鉛ビスマス溶融液中で浮いたままの粉末となった。また、空孔率が１０％を超えた状態でタングステン比率を増やすことによって見かけの密度を上昇させても、空孔率が１０％を超えることで超音波の反射率が１０％以上低下し、実効的に測定を行なうことができなくなった。ここでの空孔率は、所定の粉末を試料研磨用透明な埋め込み樹脂に投入し、研磨、光学顕微鏡での観察により測定した。例えば５０倍での光学顕微鏡観察により透明樹脂から判断できる閉空孔の面積を粒子面積で割った値を空孔率とした。密度はアルキメデス法により、空中重量と水中重量の差を容積として計算した。 In addition, in a normal manufacturing method, in order to increase the particle size of the manufactured molybdenum powder, there is a method of obtaining coarse particles by mechanically crushing a tungsten molybdenum alloy once pressed and sintered to produce slag. Conceivable. In that case, the porosity examined in the present invention exceeds 10%, for example, the porosity is 15 to 20%, and the density is less than 10.5 g / cm 3 and effectively in the lead bismuth melt. The powder was left floating. Moreover, even if the apparent density is increased by increasing the tungsten ratio in a state where the porosity exceeds 10%, the reflectance of the ultrasonic wave is decreased by 10% or more by exceeding the porosity. Effective measurement is no longer possible. The porosity here was measured by putting a predetermined powder into a transparent embedding resin for sample polishing, polishing and observing with an optical microscope. For example, the value obtained by dividing the area of the closed pores that can be determined from the transparent resin by observation with an optical microscope at 50 times the particle area was taken as the porosity. The density was calculated by the Archimedes method using the difference between the weight in air and the weight in water as the volume.
鉛ビスマス溶融液流速測定用粉末において、粒子の大きさをＡとし、測定に使用する超音波の波長Ｂに対して、ＡはＢ／４−Ｂ／２０からＢ／４＋Ｂ／１０の範囲に９割以上の粒子が分布している粉末によれば、鉛ビスマス溶融液中での超音波流速測定に関し、超音波による速度の測定に安定した粉末が得られる。Ａの最小値がＢ／４−Ｂ／２０を下回る粉末が全体の１割を超えるような粉末では、測定されるべき超音波が反射に寄与せずに吸収体となるため、測定精度が極端に低下した。また、粒子の最大値であるＢ／４＋Ｂ／１０以上の大きさの粒子が全体の１割を超えても、超音波の反射への寄与がない粒子が増加することとなり、測定感度が悪化し、誤差が５％増加した。種々の試験の結果、Ｂ／４−Ｂ／２０からＢ／４＋Ｂ／１０の範囲に９割以上の粒子が分布していることにより、１％以下の再現が可能な精密な測定を行なうことが出来た。なお、粒子の分布は島津製作所製のＳＡＬＤ−３１００にて測定を行なった。 In the powder for lead bismuth melt flow rate measurement, the particle size is A, and A is in the range of B / 4−B / 20 to B / 4 + B / 10 with respect to the wavelength B of the ultrasonic wave used for the measurement. According to the powder in which more than 30% of the particles are distributed, a powder that is stable in the measurement of the velocity by the ultrasonic wave can be obtained for the ultrasonic flow velocity measurement in the lead bismuth melt. In the powder where the minimum value of A is less than B / 4-B / 20 and exceeds 10% of the total, the ultrasonic wave to be measured does not contribute to reflection and becomes an absorber, so the measurement accuracy is extreme. Declined. In addition, even if the particle size of B / 4 + B / 10 or more, which is the maximum value of the particle, exceeds 10%, the number of particles that do not contribute to the reflection of ultrasonic waves increases and the measurement sensitivity deteriorates. The error increased by 5%. As a result of various tests, 90% or more of the particles are distributed in the range of B / 4−B / 20 to B / 4 + B / 10, so that accurate measurement capable of reproducing 1% or less can be performed. done. The particle distribution was measured with SALD-3100 manufactured by Shimadzu Corporation.
次に酸素の影響について検討を行なった。１５０℃に加熱した鉛では固溶する酸素濃度は約１０−７質量％であることが発明者により明らかにされている。超音波反射体として導入した材質が多くの酸素を含んでいると、新たな酸素供給源となり、鉛酸化物が生成され、溶融液の流動に悪影響を及ぼす。また、鉛ビスマス中酸素濃度を制御した流れでは、制御外の余分な酸素供給源は排除されなければならない。従い、酸素濃度はなるべく低い方が好ましい。好ましくは酸素濃度は５０質量ｐｐｍ以下であることが望ましいが、合金粉末は工業的には大気中で粉砕する工程を避けることは難しく酸素濃度を極限まで減らすことが困難なため、１００質量ｐｐｍを目安として制御されるべきであった。 Next, the influence of oxygen was examined. It has been clarified by the inventors that the concentration of oxygen dissolved in lead heated to 150 ° C. is about 10 −7 mass%. If the material introduced as the ultrasonic reflector contains a lot of oxygen, it becomes a new oxygen supply source, lead oxide is generated, and adversely affects the flow of the melt. Further, in the flow in which the oxygen concentration in the lead bismuth is controlled, an extra oxygen source outside the control must be excluded. Therefore, the oxygen concentration is preferably as low as possible. Preferably, the oxygen concentration is preferably 50 ppm by mass or less. However, it is difficult to avoid the process of grinding the alloy powder in the air on an industrial scale, and it is difficult to reduce the oxygen concentration to the limit. Should be controlled as a guide.
鉛ビスマス溶融液測定用粉末において、その表面をニッケルで、めっき、蒸着、スパッタなどの方法によりコーティングすることにより、粉末表面の凹凸が減少し、また、鉛ビスマスとの濡れ性が向上することによって、安定して測定を行なうことが出来るまでの時間が短く、また、測定精度も向上した状態で測定を行なうことが出来た。ニッケルの表面はその形成方法にかかわらず同様の効果を発揮し、また、ニッケルの厚みは１μｍ以上５００μｍ以下の範囲において、同様の効果をもらたした。 By coating the surface of the powder for measuring lead bismuth melt with nickel by plating, vapor deposition, sputtering, etc., the unevenness of the powder surface is reduced and the wettability with lead bismuth is improved. The time until stable measurement could be performed was short, and the measurement could be performed with improved measurement accuracy. The surface of nickel exerted the same effect regardless of its formation method, and the same effect was obtained when the nickel thickness was in the range of 1 μm to 500 μm.
これらを鉛ビスマス溶融液を用いた中性子源用液体ターゲットシステムで超音波反射体として流速測定を行なうことが可能となる。 It becomes possible to measure the flow velocity of these as ultrasonic reflectors in a liquid target system for a neutron source using a lead bismuth melt.
ドップラー効果により鉛ビスマス溶融液の流速を測定する超音波流速測定方法の詳細について以下に示す。発信器で周波数ｆｏの超音波パルス信号を流体中に発信する。超音波パルス信号が流体中の反射体に当ると、超音波が散乱し、跳ね返った超音波が受信器（発信器を兼ねる）に戻る。このときの時間遅れｔは、次の数１式で示される。
上記数１式中、ｘは、発信器と反射体間距離、ｃは液体中での音速である。 In the above equation 1, x is the distance between the transmitter and the reflector, and c is the speed of sound in the liquid.
もし、反射体が超音波発信方向に速度ｖで移動しているなら、ドップラー効果によりｆｏからｆｄだけずれた周波数が受信器に入る。ドップラー効果は次の数２式で表される。
上記数２式に従い、反射体の速度（流体の超音波方向への速度成分）ｖは、次の数３式で示される。
さらに、超音波の波長をλとすると、次の数４式で示される。
そして、超音波を反射体で跳ね返らせるためには、λと反射体粒子径は次の数５式を満たす必要がある。
例えば、４ＭＨｚの超音波周波数では、鉛ビスマスの音速を１５００ｍ／ｓ
として、波長は３７５μｍ、従い必要な反射体粒子最小直径は９４μｍとなる。２ＭＨｚの超音波に対しては反射体粒子最小直径は１８８μｍとなる。必要以上に大きな粒子は流れの細部を乱すので、好ましくない。また、小さな粒子は超音波の反射に寄与せずに測定の妨害となる。
For example, at an ultrasonic frequency of 4 MHz, the sound speed of lead bismuth is 1500 m / s.
As a result, the wavelength is 375 μm, and accordingly the required minimum diameter of the reflector particles is 94 μm. For 2 MHz ultrasonic waves, the minimum reflector particle diameter is 188 μm. Unnecessarily large particles disturb the flow details and are undesirable. In addition, small particles do not contribute to the reflection of ultrasonic waves and interfere with measurement.
ここで、超音波受信器（発信器を兼ねる）は、市販の装置を用いることが出来るが、例えばＭＥＴ−ＦＬＯＷ ＳＡ製、ＵＶＰ Ｍｏｎｉｔｏｒ Ｍｏｄｅｌ ＵＶＰ−ＤＵＯを用いて測定を行なった。上記装置の測定限界から、測定を確認できたのは４５．８〜５４９８ｍｍ／ｓの流速であった。しかし、本発明では測定装置により限定されるものでなく、測定装置の発展により上述以外への流速の対応も可能であることは当然である。 Here, as the ultrasonic receiver (also serving as a transmitter), a commercially available apparatus can be used. For example, measurement was performed using UVP Monitor Model UVP-DUO manufactured by MET-FLOW SA. It was a flow rate of 45.8-5498 mm / s that the measurement was confirmed from the measurement limit of the said apparatus. However, in the present invention, it is not limited by the measuring device, and it is natural that the flow rate other than the above can be accommodated by the development of the measuring device.
図５は上述の超音波流速測定方法を用いた本発明の核破砕中性子源ターゲットシステムの一例を示す図である。図６は図５のターゲットシステムを用いたシミュレーション結果の一例を示す図である。図５において、鉛ビスマス冷却槽１０から突出したターゲット容器１１の端部２箇所に超音波センサ１２，１３を配置している。ターゲット容器１１は、容器状の外側部１と筒状の内壁部２とを備え、ターゲット容器１１の先端外側１１ａから、陽子を白抜きの矢印１４で示すように入射させる。 FIG. 5 is a diagram showing an example of the spallation neutron source target system of the present invention using the above-described ultrasonic flow velocity measuring method. FIG. 6 is a diagram showing an example of a simulation result using the target system of FIG. In FIG. 5, ultrasonic sensors 12 and 13 are arranged at two places on the end portion of the target container 11 protruding from the lead-bismuth cooling tank 10. The target container 11 includes a container-shaped outer portion 1 and a cylindrical inner wall portion 2, and allows protons to be incident from the tip outer side 11 a of the target container 11 as indicated by a white arrow 14.
突出部１１の表面側は、矢印１５で示すように外側に向って、ターゲットとしてタングステンモリブデン合金粉末を含む鉛ビスマスからなるターゲット液が流れ、先端部で半径方向に集まり、中心側においては、ターゲット液は矢印１６で示すように流れる。 On the surface side of the projecting portion 11, a target liquid made of lead bismuth containing tungsten molybdenum alloy powder as a target flows toward the outside as indicated by an arrow 15, and gathers in the radial direction at the tip portion. The liquid flows as shown by arrow 16.
図６に示すように、容器内のターゲット液である鉛ビスマスの流速分布は、陽子の入射側に向う流れ３と、陽子の出射側から冷却槽１０に向う流れ５における矢印で示され、その矢印の大きさが流速の大きさを示している。このように、流速分布をシミュレーションだけでなく実測できることが確認でき、実測点２点とシミュレーションの差異がないことから、システム全体の流速分布についても明らかにすることができた。 As shown in FIG. 6, the flow velocity distribution of lead bismuth, which is the target liquid in the container, is indicated by arrows in the flow 3 toward the proton incident side and the flow 5 from the proton emission side toward the cooling tank 10, The size of the arrow indicates the magnitude of the flow velocity. Thus, it was confirmed that the flow velocity distribution could be measured as well as the simulation, and since there was no difference between the two measured points and the simulation, the flow velocity distribution of the entire system could be clarified.
以上説明したように、本発明に係るタングステンモリブデン合金粉末は、中性子源用の鉛ビスマス溶融液の流速を正確に測定するための超音波反射体として最適である。また、その粉末を用いたターゲットシステムも同様に鉛ビスマス溶融液の流速の測定に最適である。 As described above, the tungsten molybdenum alloy powder according to the present invention is optimal as an ultrasonic reflector for accurately measuring the flow rate of the lead bismuth melt for the neutron source. Similarly, the target system using the powder is also optimal for measuring the flow rate of the lead bismuth melt.
また、本発明に係る流速測定方法は、鉛ビスマスを溶融する場合等における精密な流速測定に最適である。 The flow velocity measuring method according to the present invention is most suitable for precise flow velocity measurement in the case of melting lead bismuth.
１ 外側部
２ 内壁部
３ 陽子の入射方向へのターゲット液の流れ
５ 冷却槽に向うターゲット液の流れ
１０ 冷却槽
１１ ターゲット容器
１２，１３ 超音波センサ
１４ 陽子の入射方向を示す矢印
DESCRIPTION OF SYMBOLS 1 Outer part 2 Inner wall part 3 Flow of target liquid to the incident direction of proton 5 Flow of target liquid toward the cooling tank 10 Cooling tank 11 Target container 12, 13 Ultrasonic sensor 14 Arrow indicating the incident direction of proton
Claims (8)
A spallation neutron source liquid target system using the ultrasonic flow velocity measuring method according to claim 7.
Priority Applications (1)
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| JP2004208648A JP4143737B2 (en) | 2004-07-15 | 2004-07-15 | Powder for measuring flow velocity of lead bismuth melt, ultrasonic flow velocity measurement method using this, and spallation neutron source liquid target system |
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| JP2004208648A JP4143737B2 (en) | 2004-07-15 | 2004-07-15 | Powder for measuring flow velocity of lead bismuth melt, ultrasonic flow velocity measurement method using this, and spallation neutron source liquid target system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104275490A (en) * | 2014-09-18 | 2015-01-14 | 株洲科能新材料有限责任公司 | Preparing method of ultra-fine bismuth powder |
| CN114574843A (en) * | 2022-02-28 | 2022-06-03 | 西安交通大学 | Composite protective film, preparation method thereof and liquid lead bismuth corrosion resistant metal tungsten |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105045990B (en) * | 2015-07-09 | 2018-07-24 | 华北电力大学 | The measuring method of lead bismuth eutectic alloy physical properties of fluids parameter and use its simulation system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104275490A (en) * | 2014-09-18 | 2015-01-14 | 株洲科能新材料有限责任公司 | Preparing method of ultra-fine bismuth powder |
| CN114574843A (en) * | 2022-02-28 | 2022-06-03 | 西安交通大学 | Composite protective film, preparation method thereof and liquid lead bismuth corrosion resistant metal tungsten |
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| JP4143737B2 (en) | 2008-09-03 |
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