JPH01187493A - Fuel element - Google Patents
Fuel elementInfo
- Publication number
- JPH01187493A JPH01187493A JP63010717A JP1071788A JPH01187493A JP H01187493 A JPH01187493 A JP H01187493A JP 63010717 A JP63010717 A JP 63010717A JP 1071788 A JP1071788 A JP 1071788A JP H01187493 A JPH01187493 A JP H01187493A
- Authority
- JP
- Japan
- Prior art keywords
- plug
- fuel
- rod
- intermediate plug
- fuel element
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000446 fuel Substances 0.000 title claims abstract description 119
- 239000000463 material Substances 0.000 claims description 8
- 239000006023 eutectic alloy Substances 0.000 claims description 7
- 239000002826 coolant Substances 0.000 claims description 5
- 239000000470 constituent Substances 0.000 claims description 2
- 238000002844 melting Methods 0.000 claims description 2
- 238000007789 sealing Methods 0.000 claims description 2
- 239000003758 nuclear fuel Substances 0.000 claims 1
- 239000000126 substance Substances 0.000 claims 1
- 238000011144 upstream manufacturing Methods 0.000 claims 1
- 230000004992 fission Effects 0.000 abstract description 13
- 238000002485 combustion reaction Methods 0.000 abstract description 8
- 239000007788 liquid Substances 0.000 abstract description 8
- 239000011734 sodium Substances 0.000 abstract description 6
- 239000007791 liquid phase Substances 0.000 abstract description 5
- 230000035699 permeability Effects 0.000 abstract description 5
- 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 abstract description 3
- 229910001093 Zr alloy Inorganic materials 0.000 abstract description 3
- 238000005304 joining Methods 0.000 abstract description 3
- 229910052708 sodium Inorganic materials 0.000 abstract description 3
- AVMSOXISNPVTNY-UHFFFAOYSA-N [Zr].[U].[Pu] Chemical compound [Zr].[U].[Pu] AVMSOXISNPVTNY-UHFFFAOYSA-N 0.000 abstract description 2
- 238000005253 cladding Methods 0.000 abstract description 2
- 230000005540 biological transmission Effects 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 19
- 229910052751 metal Inorganic materials 0.000 description 10
- 239000002184 metal Substances 0.000 description 10
- 229910052778 Plutonium Inorganic materials 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 description 5
- 230000005496 eutectics Effects 0.000 description 4
- 230000008961 swelling Effects 0.000 description 4
- 229910052770 Uranium Inorganic materials 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 3
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 2
- SGUPDEUNVHKBOH-UHFFFAOYSA-N [Fe].[U] Chemical compound [Fe].[U] SGUPDEUNVHKBOH-UHFFFAOYSA-N 0.000 description 2
- OIKBQDZWNWMZLB-UHFFFAOYSA-N [Ni].[U] Chemical compound [Ni].[U] OIKBQDZWNWMZLB-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000005025 nuclear technology Methods 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 238000009423 ventilation Methods 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 210000003323 beak Anatomy 0.000 description 1
- 238000009395 breeding Methods 0.000 description 1
- 230000001488 breeding effect Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001850 reproductive effect Effects 0.000 description 1
- 229910002058 ternary alloy Inorganic materials 0.000 description 1
Classifications
-
- 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
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、原子炉の燃料要素に係り、特に高速増殖炉の
燃料寿命の増大に好適な燃料要素に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel element for a nuclear reactor, and particularly to a fuel element suitable for increasing the fuel life of a fast breeder reactor.
従来、高速増殖炉で使用される燃料要素については、例
えば、アラン・イー・ウオルター他１名著、ファスト・
ブリーダー・リアクター、第２５３頁から第２５６頁、
パーガモン・プレス（１９８１）（Ａｌａｎ Ｅ、 ｌ
１ｌａｔｌｅｒ、 ｅｔ ａｌ、 、 Ｆａｓｔ Ｂｒ
ｅｅｄｅｒＲｅａｃｔｏｒ、 ｐｐ２５３−２５６ Ｐ
ｅｒｇａｍｏｎ Ｐｒｅｓｓ（１９８１））に記載され
ている。第１は上部端栓と下部端栓で密封した被ふく管
の内部に開口の付いた中間栓を設け、上部端栓と中間栓
に狭まれた空間に燃料棒を充てんし、また残りの空間に
は熱伝達用の媒体としてヘリウム等のガスが充てんされ
るが、この空間には核分裂反応により生成されるガスも
収納されるようになっていた。ガスは中間栓の開口を通
って下部端栓と中間栓の間の空間（下部プレナム）へ収
納されることになる。このような構成の燃料要素を下部
プレナム方式の燃料要素と称する。第２図は、その代表
例である。Regarding the fuel elements conventionally used in fast breeder reactors, for example, see Fast Breeder Reactor by Alan E. Walter and others.
Breeder Reactor, pages 253 to 256,
Pergamon Press (1981) (Alan E, l
1latler, et al, Fast Br
eederReactor, pp253-256 P
ergamon Press (1981)). The first method is to provide an intermediate plug with an opening inside the covered pipe sealed with the upper end plug and lower end plug, fill the space narrowed by the upper end plug and the intermediate plug with fuel rods, and fill the remaining space. The space was filled with a gas such as helium as a heat transfer medium, but this space also contained gas produced by nuclear fission reactions. Gas will be accommodated through the opening in the intermediate plug into the space between the lower end plug and the intermediate plug (lower plenum). A fuel element having such a configuration is called a lower plenum type fuel element. FIG. 2 is a typical example.
従来技術の第２では、上部端栓と下部端栓で密封した被
ふく管の内部に燃料棒を上部端栓よりに充てんし、残り
の空間には熱伝達用の媒体として、液体ないしガスが充
てんされるようになっていた。In the second prior art, fuel rods are filled in the covered tube sealed by the upper end plug and the lower end plug, and the remaining space is filled with liquid or gas as a heat transfer medium. It was starting to fill up.
核分裂生成ガスは、この場合、燃料棒の上側の空間（上
部プレナム）に収納されることになる。このような構成
の燃料要素を上部プレナム方式の燃料要素と称する。第
３図は、その代表例である。In this case, the fission product gas will be stored in the space above the fuel rod (upper plenum). A fuel element having such a configuration is called an upper plenum type fuel element. FIG. 3 is a typical example.
上記従来技術１は、酸化物燃料には適用できるが、以下
に述べる理由で、金属燃料には適用できない。The above-mentioned prior art 1 can be applied to oxide fuels, but cannot be applied to metal fuels for the reasons described below.
酸化物燃料よりも、燃料密度が高く、熱伝導率の高い金
属燃料を使用すると、炉心の増殖性と固有の安全性が向
上できることが知られている。金属燃料を使用した燃料
要素においても、燃料棒と被ふく管とが接触する（燃料
は中性子の照射により体積が膨張する）までは、熱伝達
用の媒体を、燃料棒と被ふく管との間のギャップに配置
しておく必要があり、このため熱伝達特性がよく、燃料
棒と被ふく管との両立性のよい液体金属を、熱伝達用の
媒体に用いることが考えられている。It is known that the use of metal fuels, which have higher fuel density and higher thermal conductivity than oxide fuels, can improve the reproductive performance and inherent safety of the reactor core. Even in fuel elements using metal fuel, the heat transfer medium is used between the fuel rods and the sheath tube until they come into contact (the fuel expands in volume due to neutron irradiation). Therefore, it is considered that liquid metal, which has good heat transfer properties and is compatible with the fuel rods and the cladding tube, may be used as a heat transfer medium.
しかるに、上記従来技術１は、液相の熱伝達用媒体を用
いた場合、これが中間栓の開口を通って下部プレナムへ
流出するという点について配慮がなく、その結果、燃料
の燃焼によりギャップ部が閉じる以前に、ギャップ部の
熱伝達用媒体が喪失するという問題があった。However, in Prior Art 1, when a liquid phase heat transfer medium is used, no consideration is given to the fact that the liquid phase flows out into the lower plenum through the opening of the intermediate plug, and as a result, the gap portion is closed due to combustion of the fuel. There was a problem in that the heat transfer medium in the gap was lost before it was closed.
上記従来技術２は、金属燃料への適用は可能である（ギ
ャップ部の熱伝達用媒体の喪失は生じないため）が、冷
却材温度が高い燃料棒の上側（冷却材は下から上へ流れ
る）にプレナムを設けたことにより、下部プレナム方式
の燃料要素と比べて、プレナム内のガス圧が高くなるた
め、被ふく管がクリープ変形し易くなる結果、燃料寿命
が短くなるという問題があった。Conventional technology 2 above can be applied to metal fuels (because there is no loss of heat transfer medium in the gap), but it can be applied to the upper part of the fuel rod where the coolant temperature is high (the coolant flows from the bottom to the top). ), the gas pressure inside the plenum is higher than that of a lower plenum type fuel element, making the covered pipe more susceptible to creep deformation, resulting in a shortened fuel life. .
本発明の目的は、金属燃料および液相の熱伝達用媒体を
使用した下部プレナム方式の燃料要素において、燃料の
燃焼に伴う体積膨張よりギャップ部が閉じるまでの間、
ギャップ部に液相の熱伝達媒体を保持でき、かつ、核分
裂で生成されるガスを下部プレナムへ収納できる構造を
持った燃料要素を提供することにある。An object of the present invention is to provide a lower plenum type fuel element using a metal fuel and a liquid phase heat transfer medium, until the gap closes due to volumetric expansion accompanying combustion of the fuel.
It is an object of the present invention to provide a fuel element having a structure capable of retaining a liquid phase heat transfer medium in a gap portion and storing gas produced by nuclear fission in a lower plenum.
上記目的は、燃料棒と、これを密封する被ふく管、上部
端栓および下部端栓、並びに上部端栓と下部端栓の中間
に位置する中間栓からなる燃料要素において、燃料棒を
中間栓の上側に置き、中間栓に通気孔を設け、燃料棒の
下端を前記通気孔を覆って中間栓の上端に接合する（例
えば、燃料棒と中間栓を構成する物質同志の共晶反応に
よる）ことにより達成される。The above purpose is to connect the fuel rod to the intermediate plug in a fuel element consisting of a fuel rod, a cover tube for sealing it, an upper end plug, a lower end plug, and an intermediate plug located between the upper end plug and the lower end plug. A vent hole is provided in the intermediate plug, and the lower end of the fuel rod is bonded to the upper end of the intermediate plug by covering the vent hole (for example, by a eutectic reaction between the materials constituting the fuel rod and the intermediate plug). This is achieved by
本発明の２つの作用： （１）燃料棒と被ふく管の間の
ギャップ部からの熱伝達用媒体の流失防止および（２）
核分裂生成ガスの下部プレナムの収納について以下説明
する。Two functions of the present invention: (1) Preventing the heat transfer medium from flowing out from the gap between the fuel rod and the envelope tube; and (2)
The storage of fission product gas in the lower plenum will be explained below.
（１）ギャップ部からの熱伝達用媒体の流失防止通気孔
の付いた中間栓の上端に、燃料棒の下端を、前記通気孔
を覆って接合することにより、熱伝達用媒体の流失は阻
止される。この場合、燃料棒と中間栓の構成物質からな
る共晶合金により接合するのが、燃料要素の製造工程の
複雑化防止、接合部の体積低減等の観点から、他の機械
的な拘束方法より優れている。燃料体と中間栓を両者の
共晶反応により接合するためには、両者を密着して、一
定温度（共晶反応温度）以上で所定時間保持すればよく
、接合部に生成される共晶合金の厚みは、数百μｍと薄
い。(1) Preventing loss of heat transfer medium from the gap By joining the lower end of the fuel rod to the upper end of the intermediate plug with a vent hole, covering the vent hole, the loss of heat transfer medium is prevented. be done. In this case, joining using a eutectic alloy consisting of the constituent materials of the fuel rods and intermediate plug is preferable to other mechanical restraint methods, from the viewpoint of preventing complication of the fuel element manufacturing process and reducing the volume of the joint. Are better. In order to join the fuel body and the intermediate plug through a eutectic reaction between the two, it is sufficient to bring them into close contact and hold them at a certain temperature (eutectic reaction temperature) or higher for a predetermined period of time. The thickness is as thin as several hundred μm.
（２）核分裂で生成されたガスの下部プレナムへの収納
、金属燃料（例えば、ウラン・プルトニウム・ジルコニ
ウムからなる三元合金：ｕ−Ｐｕ−Ｚｒ）は、一般に、
燃焼の進展に伴いその体積が膨張（スエリング）する。(2) Storage of gas produced by nuclear fission in the lower plenum, metal fuel (for example, ternary alloy consisting of uranium, plutonium, and zirconium: u-Pu-Zr) is generally
As combustion progresses, its volume expands (swells).
燃焼の進展の度合は燃焼度（核分裂反応した燃料の原子
数と始めの燃料原子の総数の比）で表わされる。ジャー
ナル オブ ヌークリア テクノロジー、第６５巻（１
９８４）第１７９頁から第２３１頁（Ｊｏｕｒｎａｌ
ｏｆ Ｎｕｃｌｅａｒ Ｔｅｃｈｎｏｌｏｇｙ、 Ｖｏ
ｌ、 ６５（１９８４）ｐｐ１７９−２３１）に記載の
ように、金属燃料では、スエリング量がある程度大きく
なると、合金燃料内部に滞まっていた核分裂ガス気泡同
志が連結し、ついには燃料表面へ通じるようになる（す
なわち、燃料が通気性を持つ）。燃料が通気性を示すス
エリング量は約３０％であり、これに対応する燃焼度は
約２％である。これ以上の燃焼度では、核分裂ガスは、
燃料体内部を進み、中間栓の通気孔を経て、下部プレナ
ムへ収納されることになる。The degree of progress of combustion is expressed by burnup (the ratio of the number of fuel atoms undergoing nuclear fission reaction to the total number of fuel atoms at the beginning). Journal of Nuclear Technology, Volume 65 (1)
984) pages 179 to 231 (Journal
of Nuclear Technology, Vo
1, 65 (1984) pp. 179-231), when the amount of swelling in a metal fuel increases to a certain extent, the fission gas bubbles that have remained inside the alloy fuel connect with each other and eventually reach the surface of the fuel. (i.e., the fuel is breathable). The amount of swelling at which the fuel exhibits air permeability is about 30%, and the corresponding burnup is about 2%. At higher burnups, fission gases
It travels inside the fuel body, passes through the vent in the intermediate plug, and is stored in the lower plenum.
ところで、燃料に通気性があると、前記ギャップ部の熱
伝達媒体も、燃料体内部を通り、下部プレナムへ流出す
る可能性があるが、この場合でもギャップが閉じている
ならば（燃料棒と被ふく管が接触した状態）、金属燃料
と被ふく管との境界に合金が形成されるため、熱伝達上
は、何ら支障がない。それには、燃料が通気性を示すの
とほぼ同時に、ギャップが閉じるように、初期のギャッ
プ幅を設定すればよい。すなわち、初期のギャップ量は
、燃料体積の約３０％相当（燃料棒の横断面積と被ふく
管内側の横断面積の比で約７５％）とすることが必要で
ある。By the way, if the fuel has air permeability, there is a possibility that the heat transfer medium in the gap section may also pass through the inside of the fuel body and flow out to the lower plenum, but even in this case, if the gap is closed (the fuel rods and Since an alloy is formed at the boundary between the metal fuel and the covered tube (the covered tubes are in contact with each other), there is no problem in terms of heat transfer. To do this, the initial gap width may be set so that the gap closes approximately at the same time that the fuel becomes air permeable. That is, the initial gap amount needs to be equivalent to about 30% of the fuel volume (the ratio of the cross-sectional area of the fuel rod to the cross-sectional area inside the envelope tube is about 75%).
以下、本発明を実施例に従って説明する。第１図は、本
発明の第１の実施例である。ステンレス製の被ふく管１
０の両端を上部端栓１１と下部端栓１２で封じ、内部に
は、ステンレス製の中間栓１３を設け、その上側に、ウ
ラン・プルトニウム・ジルコニウムの合金（Ｕ−Ｐｕ−
Ｚｒ合金：重量割合（％）の１例Ｕ ／ Ｐ ｕ ／
Ｚ ｒ ＝ ７５ ／ １５／１０）からなる燃料棒２
０を置き、その下端部２１を中間栓１３の上端１４に接
合させ、中間栓の通気孔１５を覆っている。接合部３０
は、燃料棒と中間栓の構造材からなるウラン・鉄系（Ｕ
ａＦｅ−ＵＦｅ２）およびウラン・ニッケル系（ＵＢＮ
１−Ｕ７Ｎｉｏ）の合金よりなる。熱伝達用媒質とし
て、液体ナトリウム（液体Ｎａ）４０が、中間栓の上側
の空間に充てんされ、燃料棒は、その液面４１の下にあ
る。中間栓の下側の空間は、ガスプレナム５０である。Hereinafter, the present invention will be explained according to examples. FIG. 1 shows a first embodiment of the invention. Stainless steel cover pipe 1
0 is sealed with an upper end plug 11 and a lower end plug 12, and an intermediate plug 13 made of stainless steel is provided inside, and a uranium-plutonium-zirconium alloy (U-Pu-
Zr alloy: Example of weight percentage (%) U / P u /
Fuel rod 2 consisting of Z r = 75/15/10)
0, its lower end 21 is joined to the upper end 14 of the intermediate plug 13, and covers the ventilation hole 15 of the intermediate plug. Joint part 30
is a uranium-iron-based (U
aFe-UFe2) and uranium-nickel system (UBN
1-U7Nio) alloy. As a heat transfer medium, liquid sodium (liquid Na) 40 is filled in the space above the intermediate plug, and the fuel rods are below the liquid level 41. The space below the intermediate plug is a gas plenum 50.
燃料棒と被ふく管の間のギャップ６０は、前述のように
、燃焼度が２％以下（スエリング量で〜３０％以下）で
は、開いている。このとき、燃料棒は、また通気性がな
く（核分裂ガスは、燃料内部に滞る）、また前記の接合
部３０が存在するため、液体Ｎａ４０は、中間栓の上側
の空間に完全に密封され、下部プレナムへ流出すること
はない。As described above, the gap 60 between the fuel rod and the envelope tube is open when the burnup is 2% or less (~30% or less in terms of swelling amount). At this time, the fuel rod also has no air permeability (fission gas remains inside the fuel), and the above-mentioned joint 30 exists, so the liquid Na 40 is completely sealed in the space above the intermediate plug. There is no leakage into the lower plenum.
したがって、ギャップ部の熱伝達特性は良好である。Therefore, the heat transfer characteristics of the gap portion are good.
次に、同じ実施例で、燃焼が進み、ギャップが閉じた場
合を、第４図により説明する。燃焼度は２％以上（スエ
リング量で３０％以上）である。Next, a case in which combustion progresses and the gap closes in the same embodiment will be explained with reference to FIG. 4. The burnup is 2% or more (swelling amount is 30% or more).
この場１合、燃料棒は通気性であり、核分裂ガスは、燃
料棒内部を通って下部プレナムへ収納される。In this case, the fuel rods are vented and the fission gases are accommodated through the interior of the fuel rods into the lower plenum.
液体Ｎａは、一部が燃料棒内部の通気孔に残るが、大半
は下部プレナムの底に貯まるごとになる。ギャップが閉
じているため、燃料体と被ふく管との間の熱伝達は良好
である。A portion of the liquid Na remains in the vents inside the fuel rods, but most of it accumulates at the bottom of the lower plenum. Since the gap is closed, heat transfer between the fuel body and the envelope tube is good.
本発明の第２の実施例を、第５図に示す。本実施例は、
中間栓１３の一部を多孔質９としたものであり、第１の
実施例と同様の機能を持っている。A second embodiment of the invention is shown in FIG. In this example,
A part of the intermediate stopper 13 is made of porous material 9, and has the same function as the first embodiment.
本発明の第３の実施例を第６図に示す。この例では、第
１．第２の実施例のように、燃料体本体と中間栓を直接
、接合しないで、中間栓の上端部に共晶合金領域７０を
形成し、中間栓の通気孔を接合部３１により覆っている
。燃焼が進むと、共晶合金領域７０も通気性を持つよう
になるので、第１．第２の実施例と同様の機能がある。A third embodiment of the invention is shown in FIG. In this example, the first. As in the second embodiment, the fuel body body and the intermediate plug are not directly joined, but a eutectic alloy region 70 is formed at the upper end of the intermediate plug, and the vent hole of the intermediate plug is covered by the joint part 31. . As the combustion progresses, the eutectic alloy region 70 also becomes breathable, so the first. It has the same functions as the second embodiment.
本発明の第４の実施例を第７図に示す。この例では、燃
料棒下端部２１の燃料組成をウラン７０％、プルトニウ
ム２０％、ジルコニウム１０％とし、プルトニウムの比
率を、下端部以外の燃料２０（プルトニウムの比率１５
％）より高くしている。ウラン・鉄系およびウラン・ニ
ッケル系の共晶の生成温度は、ウランより融点の低いプ
ルトニウムの比率の高い燃料はど低下するので、本実施
例のような燃料棒の構成とすることにより、燃料棒下端
と中間栓上端部による共晶合金の生成が一層容易になる
。A fourth embodiment of the invention is shown in FIG. In this example, the fuel composition of the fuel rod lower end 21 is 70% uranium, 20% plutonium, and 10% zirconium, and the plutonium ratio is set to 20% in the fuel other than the lower end (plutonium ratio 15%).
%) is higher. The formation temperature of uranium-iron-based and uranium-nickel-based eutectics decreases in fuels with a high proportion of plutonium, which has a lower melting point than uranium. The formation of a eutectic alloy by the lower end of the rod and the upper end of the intermediate stopper becomes easier.
本発明によれば、金属燃料が使用した燃料要素において
、核分裂生成ガスを収納するガスプレナムを、従来、燃
料棒の上側にしか置けなかったのが、温度の低い燃料棒
の下側に置けるようになつた。これによる効果は次の通
りである。According to the present invention, in a fuel element using metal fuel, the gas plenum that stores the fission product gas could previously be placed only above the fuel rods, but now it can be placed below the fuel rods where the temperature is low. Summer. The effects of this are as follows.
一般に、金属燃料を使用した燃料要素の寿命τは、核分
裂生成ガス圧力Ｐ（寿命中の平均値）により被ふく管に
発生する、被ふく管の周方向の応力σＨ（寿命中の平均
値）に対して、近似的に−σＨ−ｐ／ｌ
・・・（１）τ ｃｃ ｅ ｃｃ ｅ
となる。ここでｔは被ふく管肉厚である。一方、圧力Ｐ
は、取出燃焼度をＢ、プレナム温度をＴ。In general, the life τ of a fuel element using metal fuel is defined as the stress σH in the circumferential direction of the envelope tube (average value during the lifetime) generated in the envelope tube due to the fission product gas pressure P (average value during the lifetime). , approximately -σH-p/l
...(1) τ cc e cc e . Here, t is the wall thickness of the envelope tube. On the other hand, pressure P
, the extraction burnup is B, and the plenum temperature is T.
プレナム長をＱとすると、
ＰｃｃＢＸＴＸ１／１１！ −（２）
となる。式（１）と（２）により次式を得る。If the plenum length is Q, then PccBXTX1/11! -(2)
becomes. The following equation is obtained from equations (1) and (2).
＋７ＨＣＣＢ ＸＴＸ １／ Ｑ Ｘ １／ ｔ
・・・（３）上部プレナム温度〜６５０℃に対して、
下部プレナム温度は〜３５０℃であるので、σＨｔＱ＊
を同一の条件下では、取出燃焼度Ｂｃｃｌ／Ｔとなるか
ら、本発明による下部プレナム方式の燃料要素では、従
来の上部プレナム方式の燃料要素と比に増大することが
できる。この様子の一例を第８図に示した。この図は、
燃焼度とガス圧力の関係を、下部および上部プレナム方
式の燃料要素について示したものである。これより、ガ
ス圧力が同一ならば、下部プレナム方式の燃料要素の燃
焼度は、上部プレナム方式と比べ、約１．５倍となる。+7HCCB XTX 1/ Q X 1/t
...(3) For upper plenum temperature ~650℃,
Since the lower plenum temperature is ~350°C, σHtQ*
Under the same conditions, the extraction burnup becomes Bccl/T, so in the lower plenum type fuel element according to the present invention, it can be increased compared to the conventional upper plenum type fuel element. An example of this situation is shown in FIG. This diagram is
The relationship between burnup and gas pressure is shown for lower and upper plenum fuel elements. From this, if the gas pressure is the same, the burnup of the fuel element in the lower plenum type is approximately 1.5 times that in the upper plenum type.
燃料コストは、燃焼度とほぼ逆比例の関係にあるから、
この場合、約２／３に低減される。Since fuel cost is almost inversely proportional to burnup,
In this case, it is reduced to about 2/3.
また、式（３）より、σＨ，Ｂを一定とすると、ｔ （
Ｘ：Ｔ、またはＱＣＣＴとなるから、本発明により、被
ふく管肉厚の低減あるいはプレナム長の短縮（夫々、約
１／３減）が可能となる。したがって、本発明による燃
料要素を使用した燃料集合体で炉心を構成すると、前者
の効果により構造材による中性子の吸収が小さい炉心、
すなわち増殖性に優れた炉心を構築でき、また後者の効
果により燃料要素長が短縮されるため、冷却材の圧力損
失が減少することにより、冷却材を駆動するポンプの容
量を低減できる。Also, from equation (3), if σH, B are constant, t (
Since X:T or QCCT, the present invention makes it possible to reduce the wall thickness of the covered tube or shorten the plenum length (about 1/3 reduction, respectively). Therefore, when a reactor core is constructed with a fuel assembly using the fuel element according to the present invention, the former effect results in a reactor core in which the absorption of neutrons by the structural materials is small.
That is, it is possible to construct a reactor core with excellent multiplication properties, and the latter effect shortens the fuel element length, which reduces the pressure loss of the coolant, thereby reducing the capacity of the pump that drives the coolant.
以上のごとく、本発明によれば、高速増殖炉の燃料コス
ト低減、増殖性の向上、ポンプ容量の低減等、経済性の
大幅な向上が可能となる。As described above, according to the present invention, it is possible to significantly improve the economic efficiency of a fast breeder reactor, such as reducing fuel cost, improving breeding performance, and reducing pump capacity.
第１図（ａ）は本発明の第１実施例による燃料要素の縦
断面図、第１図（ｂ）は第１図（ａ）のＡ部拡大図、第
２図は従来の燃料要素の縦断面図、第３図は他の従来例
の燃料要素の縦断面図、第４図は第１実施例の燃焼進行
後の燃料要素の縦断面図、第５図（、）は本発明の第２
実施例による燃料要素の縦断面図、第５図（ｂ）は第５
図（ａ）のＢ部拡大図、第６図（ａ）は本発明の第３実
施例による燃料要素の縦断面図、第６図（ｂ）は第６図
（、）のＣ部拡大図、第７図（、）は本発明の第４実施
例による燃料要素の縦断面図、第７図（ｂ）は第７図（
ａ）のＤ部拡大図、第８図は燃焼度とプレナム圧力の関
係グラフ図である。
１０・・・被ふく管、１１・・・上部端栓、１２・・・
下部端栓、１３・・・中間栓、１５・・・通気孔、２０
・・・燃料棒、３０・・・燃料棒と中間栓の接合部、５
０・・・ガスプレギ１０（呻
ｌσ−草覆嘴
）／ −ｍ−士＃５４洟ｔ
ｔｚ−７４シ裔栓
／３− 中間、売ｔ
３σ−一力哄ｐｒ１４と中ｆ１膚針の幹部４θ −一寒
’＜４−ｆｔｐリウへ
５θ−−一力゛ズデｌ／カム
７、ｎ−−ギＶツフ１
第２ 図
第４０
第 ５ｒ’Ａ（ｄ）
茶乙図（Ｖ
ふｒ Ａ ｅｆ′Ｉ
第７図（４）
弔 乙 ＬFIG. 1(a) is a vertical sectional view of a fuel element according to a first embodiment of the present invention, FIG. 1(b) is an enlarged view of section A in FIG. 1(a), and FIG. 2 is a diagram of a conventional fuel element. 3 is a vertical sectional view of a fuel element of another conventional example, FIG. 4 is a vertical sectional view of a fuel element of the first embodiment after combustion progresses, and FIG. Second
A vertical cross-sectional view of a fuel element according to an embodiment, FIG. 5(b) is a fifth
FIG. 6(a) is an enlarged view of section B in FIG. 6(a), FIG. 6(a) is a longitudinal sectional view of a fuel element according to the third embodiment of the present invention, and FIG. 6(b) is an enlarged view of section C in FIG. , FIG. 7(,) is a longitudinal sectional view of a fuel element according to a fourth embodiment of the present invention, and FIG. 7(b) is a longitudinal sectional view of a fuel element according to a fourth embodiment of the present invention.
FIG. 8, an enlarged view of part D in a), is a graph showing the relationship between burnup and plenum pressure. 10... Covered pipe, 11... Upper end plug, 12...
Lower end plug, 13... Middle plug, 15... Ventilation hole, 20
...Fuel rod, 30...Joint part of fuel rod and intermediate plug, 5
0...Gaspregi 10 (moan lσ-grass cover beak) / -m-shi #54 t tz-74 shibutsu / 3- middle, sell t 3σ-ichirikari pr14 and middle f1 skin needle executive 4θ -Ichikan'<4-ftp riu to 5θ--Ichirikizude l/cam 7, n--Gi Vtsufu 1 Fig. 2 Fig. 40 No. 5r'A (d) Tea diagram (V fr A ef 'I Figure 7 (4) Condolence Otsu L
Claims (1)
ふく管、上部端栓、および下部端栓、並びに上部端栓と
下部端栓の中間に位置する中間栓からなる原子炉の燃料
要素において、燃料棒が中間栓の上側にあり、中間栓が
通気孔を有し、燃料棒の下端が前記通気孔を覆つて中間
栓の上端に接合され、接合部が燃料棒と中間栓を構成す
る物質よりなる共晶合金であることを特徴とする燃料要
素。 ２、核分裂性物質等を含む燃料棒を被ふく管内に封入し
た原子炉の燃料要素において、燃料要素を、これと並行
して流れる冷却材の上流側の第１領域と、下流側の第２
領域とに、通気孔のある中間栓を介して分け、前記第２
領域に、燃料棒を配し、燃料棒と中間栓の接合部に、燃
料棒と中間栓を構成する物質からなる共晶合金を形成し
、前記通気孔を覆つたことを特徴とする燃料要素。 ３、前記中間栓の一部が多孔質であることを特徴とする
特許請求の範囲第１項又は第２項の燃料要素。 ４、前記中間栓の一部が、燃料棒と中間栓母材の構成物
質からなる共晶合金であることを特徴とする特許請求の
範囲第１項又は第２項の燃料要素。 ５、前記燃料棒に含まれる低融点燃料元素の割合が、前
記接合部に関与する燃料棒端部で大きく、端部以外で小
さいことを特徴とする特許請求の範囲第１項から第４項
までのいずれかの燃料要素。[Scope of Claims] 1. A fuel rod containing fissile material, etc., a covering tube for sealing it, an upper end plug, a lower end plug, and an intermediate plug located between the upper end plug and the lower end plug. In the fuel element for a nuclear reactor, the fuel rod is located above the intermediate plug, the intermediate plug has a vent hole, the lower end of the fuel rod is joined to the upper end of the intermediate plug over the vent hole, and the joint portion is A fuel element characterized in that it is a eutectic alloy of materials constituting the fuel rods and the intermediate plug. 2. In a nuclear reactor fuel element in which fuel rods containing fissile material, etc. are enclosed in an envelope tube, the fuel element is divided into a first region on the upstream side and a second region on the downstream side of the coolant flowing in parallel with the fuel element.
and the second region through an intermediate stopper with a vent, and
A fuel element characterized in that a fuel rod is disposed in the region, a eutectic alloy made of a substance constituting the fuel rod and the intermediate plug is formed at a joint between the fuel rod and the intermediate plug, and the vent hole is covered. . 3. The fuel element according to claim 1 or 2, wherein a part of the intermediate plug is porous. 4. The fuel element according to claim 1 or 2, wherein a part of the intermediate plug is made of a eutectic alloy consisting of the constituent materials of the fuel rod and the intermediate plug base material. 5. Claims 1 to 4, characterized in that the proportion of the low-melting point fuel element contained in the fuel rod is large at the ends of the fuel rods involved in the joints, and small at the ends other than the ends. Any fuel element up to.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63010717A JP2510648B2 (en) | 1988-01-22 | 1988-01-22 | Fuel element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63010717A JP2510648B2 (en) | 1988-01-22 | 1988-01-22 | Fuel element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01187493A true JPH01187493A (en) | 1989-07-26 |
| JP2510648B2 JP2510648B2 (en) | 1996-06-26 |
Family
ID=11758050
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63010717A Expired - Lifetime JP2510648B2 (en) | 1988-01-22 | 1988-01-22 | Fuel element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2510648B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100963472B1 (en) * | 2008-04-17 | 2010-06-17 | 한국원자력연구원 | Metallic fuel rod in metal sheath including metallic fuel particles and a preparation method thereof |
| JP2015092161A (en) * | 2009-06-01 | 2015-05-14 | アドバンスト・リアクター・コンセプツ・エルエルシー | Particulate metal fuels used in power generation, recycling systems, and small modular reactors |
| US9640283B2 (en) | 2010-01-29 | 2017-05-02 | Advanced Reactor Concepts LLC | Small, fast neutron spectrum nuclear power plant with a long refueling interval |
| US10424415B2 (en) | 2014-04-14 | 2019-09-24 | Advanced Reactor Concepts LLC | Ceramic nuclear fuel dispersed in a metallic alloy matrix |
-
1988
- 1988-01-22 JP JP63010717A patent/JP2510648B2/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100963472B1 (en) * | 2008-04-17 | 2010-06-17 | 한국원자력연구원 | Metallic fuel rod in metal sheath including metallic fuel particles and a preparation method thereof |
| JP2015092161A (en) * | 2009-06-01 | 2015-05-14 | アドバンスト・リアクター・コンセプツ・エルエルシー | Particulate metal fuels used in power generation, recycling systems, and small modular reactors |
| US9640283B2 (en) | 2010-01-29 | 2017-05-02 | Advanced Reactor Concepts LLC | Small, fast neutron spectrum nuclear power plant with a long refueling interval |
| US10424415B2 (en) | 2014-04-14 | 2019-09-24 | Advanced Reactor Concepts LLC | Ceramic nuclear fuel dispersed in a metallic alloy matrix |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2510648B2 (en) | 1996-06-26 |
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