JP2911866B1 - Method for producing nuclear fuel pellets - Google Patents

Method for producing nuclear fuel pellets

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Publication number
JP2911866B1
JP2911866B1 JP10029278A JP2927898A JP2911866B1 JP 2911866 B1 JP2911866 B1 JP 2911866B1 JP 10029278 A JP10029278 A JP 10029278A JP 2927898 A JP2927898 A JP 2927898A JP 2911866 B1 JP2911866 B1 JP 2911866B1
Authority
JP
Japan
Prior art keywords
nuclear fuel
outer peripheral
peripheral surface
sintering aid
fuel
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.)
Expired - Fee Related
Application number
JP10029278A
Other languages
Japanese (ja)
Other versions
JPH11211871A (en
Inventor
崎 仁 石
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NIPPON NYUKURIA FUYUERU KK
Original Assignee
NIPPON NYUKURIA FUYUERU KK
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by NIPPON NYUKURIA FUYUERU KK filed Critical NIPPON NYUKURIA FUYUERU KK
Priority to JP10029278A priority Critical patent/JP2911866B1/en
Application granted granted Critical
Publication of JP2911866B1 publication Critical patent/JP2911866B1/en
Publication of JPH11211871A publication Critical patent/JPH11211871A/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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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

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  • Compositions Of Oxide Ceramics (AREA)

Abstract

【要約】 【課題】 クリープ抵抗性を低減し得る核燃料ペレット
の製造方法を得ること。 【解決手段】 核燃料粉末を加圧成形して成形体を形成
し、その成形体の外周面及び端面の少なくとも一方に焼
結助剤を塗布した後、その成形体を焼結する。A method for producing nuclear fuel pellets capable of reducing creep resistance is provided. SOLUTION: A nuclear fuel powder is press-molded to form a compact, and after applying a sintering aid to at least one of an outer peripheral surface and an end face of the compact, the compact is sintered.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、核燃料棒用の核燃
料ペレットの製造方法に関する。The present invention relates to a method for producing nuclear fuel pellets for nuclear fuel rods.

【０００２】[0002]

【従来の技術及び発明が解決しようとする課題】原子炉
においては、一般に二酸化ウランもしくは酸化プルトニ
ウム入り二酸化ウラン等の核燃料酸化物の焼結体からな
るペレットを燃料被覆管中に封入して燃料棒を構成し、
その燃料棒を格子状に束ねた燃料集合体が燃料として使
用される。2. Description of the Related Art In a nuclear reactor, a pellet made of a sintered body of nuclear fuel oxide such as uranium dioxide or uranium dioxide containing plutonium oxide is generally sealed in a fuel cladding tube to form a fuel rod. Constitute
A fuel assembly in which the fuel rods are bundled in a grid is used as fuel.

【０００３】この燃料被覆管内に封入されるペレット
は、核燃料酸化物の粉末を加圧成形し、これを焼結しさ
らに焼結体の外周面を研削することによって形成され
る。[0003] The pellets sealed in the fuel cladding tube are formed by pressing and molding nuclear fuel oxide powder, sintering the powder, and grinding the outer peripheral surface of the sintered body.

【０００４】ところで、燃料集合体設計においては、経
済設計の観点から燃料の高燃焼度化が進められており、
この燃料の高燃焼度化に伴う問題の一つとして、ペレッ
トと燃料被覆管との機械的相互作用の問題がある。この
問題への対策としては、燃料被覆管の内側に柔らかな金
属を張り付ける方法が採られている。また、燃料ペレッ
トのクリープ抵抗性を小さくするために種々の化合物の
添加が検討されており、この化合物を核燃料酸化物の粉
末に添加、混合することにより、燃料ペレットを構成す
る焼結体中にその化合物が均一に分布される。[0004] In the fuel assembly design, higher burnup of fuel has been promoted from the viewpoint of economic design.
One of the problems associated with the higher burnup of fuel is the problem of mechanical interaction between the pellets and the fuel cladding tube. As a measure against this problem, a method of attaching a soft metal to the inside of the fuel cladding tube has been adopted. Also, addition of various compounds to reduce the creep resistance of the fuel pellets has been studied. By adding and mixing this compound to the nuclear fuel oxide powder, the compound is added to the sintered body constituting the fuel pellet. The compound is uniformly distributed.

【０００５】しかしながら、クリープ抵抗性を小さくす
るために化合物を添加、混合する場合には、混合工程を
一工程追加する必要があるとともに、化合物が焼結体中
に均一に分布するために、燃料被覆管との機械的相互作
用が発生する焼結体の外周面近傍においては、必ずしも
クリープ抵抗の低減効果を十分生じさせ得る程度にはな
らない場合がある等の問題がある。However, when a compound is added and mixed in order to reduce creep resistance, it is necessary to add one mixing step, and since the compound is uniformly distributed in the sintered body, the fuel must be added. In the vicinity of the outer peripheral surface of the sintered body where the mechanical interaction with the cladding tube occurs, there is a problem that the effect of reducing the creep resistance may not always be sufficiently obtained.

【０００６】本発明は、このような点に鑑み、核燃料ペ
レットのクリープ抵抗性を十分低減し得るようにした核
燃料ペレットの製造方法を得ることを目的とする。SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a method for producing nuclear fuel pellets capable of sufficiently reducing creep resistance of nuclear fuel pellets.

【０００７】[0007]

【課題を解決するための手段】本発明は、核燃料粉末を
加圧成形して成形体を形成し、その成形体の外周面及び
端面の少なくとも一方に焼結助剤を塗布し、その焼結助
剤が塗布された成形体を焼結し、ペレットの外周面近傍
の結晶粘界に焼結助剤を析出させるようにしたことを特
徴とする。SUMMARY OF THE INVENTION According to the present invention, a compact is formed by press-molding nuclear fuel powder, and a sintering aid is applied to at least one of the outer peripheral surface and the end surface of the molded product. The molded body on which the auxiliary agent is applied is sintered to precipitate the sintering auxiliary agent in the crystal viscous boundary near the outer peripheral surface of the pellet.

【０００８】[0008]

【発明の実施の形態】核燃料用原料粉末としては、二酸
化ウランその他の酸化ウラン、酸化プルトニウム、酸化
トリウム等が挙げられ、これらが１種または２種以上混
合して用いられる。また、酸化ガドリニウムなどの中性
子吸収物質との混合物としても用いられる。BEST MODE FOR CARRYING OUT THE INVENTION As raw material powder for nuclear fuel, uranium dioxide, other uranium oxide, plutonium oxide, thorium oxide and the like can be mentioned, and these can be used alone or in combination of two or more. It is also used as a mixture with a neutron absorbing substance such as gadolinium oxide.

【０００９】そこで、このような核燃料用原料粉末を成
形機の金型に充填し、例えば０．５〜５ｔａｎ／ｃｍ2
程度の圧力で成形して、４０〜６０％ＴＤ（理論密度の
４０〜６０％、理論密度は二酸化ウランの場合１０．９
５ｇ／ｃｍ3 ）の成形体を形成する。Therefore, such a raw material powder for a nuclear fuel is filled in a mold of a molding machine, for example, 0.5 to 5 tan / cm 2.
TD (40-60% of theoretical density, theoretical density is 10.9% for uranium dioxide)
5 g / cm 3 ) is formed.

【００１０】次いで、成形体外周面又は端面、或は成形
体外周面及び端面に焼結助剤を塗布する。この焼結助剤
としては酸化アルミニウムと二酸化珪素の混合物、或は
アルミノケイ酸塩等が用いられる。また、上記焼結助剤
の塗布の方法としては、粉末をそのまま塗布する方式、
溶液として塗布する方式、或は懸濁液として塗布する方
式を採用することができる。Next, a sintering aid is applied to the outer peripheral surface or the end surface of the molded body, or the outer peripheral surface and the end surface of the molded body. As the sintering aid, a mixture of aluminum oxide and silicon dioxide, or an aluminosilicate is used. Further, as a method of applying the sintering aid, a method of applying the powder as it is,
A method of applying as a solution or a method of applying as a suspension can be adopted.

【００１１】このようにして焼結助剤が塗布された成形
体を、水素雰囲気中、水素と窒素の混合ガスからなる還
元性雰囲気中、二酸化炭素の分解を利用した酸化性雰囲
気中、或はアルゴン等の不活性ガス雰囲気中において約
１５００〜１８００℃の温度で約１〜１０時間の条件下
で焼結する。The molded body coated with the sintering agent in this manner is placed in a hydrogen atmosphere, in a reducing atmosphere consisting of a mixed gas of hydrogen and nitrogen, in an oxidizing atmosphere utilizing decomposition of carbon dioxide, or Sintering is performed in an atmosphere of an inert gas such as argon at a temperature of about 1500 to 1800 ° C. for about 1 to 10 hours.

【００１２】しかして、このようにして得られた核燃料
ペレットは、焼結時に焼結助剤が融解し、焼結体表面に
一様に拡散し、外周面近傍及び端面近傍の結晶粒が成長
することにより、結晶粒界に焼結助剤が析出し、クリー
プ抵抗性の小さいペレットが得られる。In the nuclear fuel pellets thus obtained, the sintering aid is melted during sintering and diffuses uniformly on the surface of the sintered body, and crystal grains near the outer peripheral surface and near the end surface grow. By doing so, the sintering aid precipitates at the crystal grain boundaries, and pellets with low creep resistance are obtained.

【００１３】そこで、上述のようにして得られたペレッ
トを、例えば研削によって所望の形状とし、これを燃料
被覆管内に装填し、不活性ガス中で密封して燃料棒を形
成し、さらにこの燃料棒を束ねて燃料集合体を構成す
る。Therefore, the pellets obtained as described above are formed into a desired shape by, for example, grinding, loaded into a fuel cladding tube, sealed in an inert gas to form a fuel rod, and The rods are bundled to form a fuel assembly.

【００１４】（実施例１）核燃料用原料粉末を粉末成形
することにより形成された成形体の端面にイソステアリ
ン酸を塗布し、その上に酸化アルミニウムと二酸化珪素
の混合物の粉末を散布し、その後上記成形体を焼成し焼
結体を得た。(Example 1) Isostearic acid is applied to an end face of a molded body formed by powder molding of a raw material powder for nuclear fuel, and a powder of a mixture of aluminum oxide and silicon dioxide is sprayed thereon, and thereafter, The molded body was fired to obtain a sintered body.

【００１５】図１の（ａ），（ｂ）は上記方法で製造し
たペレットの中心部および外周面近傍部の結晶構造を示
す顕微鏡写真であって、図１の（ｂ）に示すようにペレ
ットの外周面近傍の結晶粒径が図１の（ａ）に示すペレ
ットの内部の結晶粒径より大きくなり、ペレット外周面
近傍の結晶粒界に焼結助剤が析出したことがわかる。 （実施例２）アルミノケイ酸塩をイソステアリン酸に懸
濁させ、その懸濁液を筆によって、核燃料用原料粉末を
粉末成形した成形体の外周面及び端面に塗布し、その後
上記成形体を焼成し焼結体を得た。FIGS. 1 (a) and 1 (b) are photomicrographs showing the crystal structure of the central portion and the vicinity of the outer peripheral surface of the pellet produced by the above method. As shown in FIG. It can be seen that the crystal grain size in the vicinity of the outer peripheral surface became larger than the crystal grain size in the inside of the pellet shown in FIG. 1A, and the sintering aid precipitated at the crystal grain boundary near the outer peripheral surface of the pellet. (Example 2) An aluminosilicate is suspended in isostearic acid, and the suspension is applied with a brush to the outer peripheral surface and the end surface of a molded product obtained by molding a raw material powder for nuclear fuel, and then the molded product is fired. A sintered body was obtained.

【００１６】図２の（ａ），（ｂ）は上記方法で製造し
たペレットの中心部および外周面近傍部の結晶構造を示
す顕微鏡写真であって、図２の（ｂ）に示すようにペレ
ットの外周面近傍の結晶粒径が図２の（ａ）に示すペレ
ットの内部の結晶粒径より大きくなり、ペレット外周面
近傍の結晶粒界に焼結助剤が析出したことがわかる。FIGS. 2A and 2B are photomicrographs showing the crystal structure of the central portion and the vicinity of the outer peripheral surface of the pellet produced by the above method. As shown in FIG. It can be seen that the crystal grain size in the vicinity of the outer peripheral surface became larger than the crystal grain size in the inside of the pellet shown in FIG. 2A, and the sintering aid precipitated at the crystal grain boundary near the outer peripheral surface of the pellet.

【００１７】[0017]

【発明の効果】以上説明したように、本発明は核燃料粉
末を加圧成形した成形体の外周面及び端面の少なくとも
一方に焼結助剤を塗布した後焼結することにより、ペレ
ットの外周面近傍の結晶粒界に焼結助剤を析出させるよ
うにしたので、ペレットの外周面近傍における、クリー
プ抵抗性が小さい焼結体からなるペレットを得ることが
できる。したがって、核燃料粉末内に焼結剤を添加して
混合させる等の工程を用いる必要がない等の効果を奏す
る。As described above, according to the present invention, the sintering aid is applied to at least one of the outer peripheral surface and the end surface of the compact obtained by press-molding the nuclear fuel powder, followed by sintering. Since the sintering aid is precipitated at the nearby crystal grain boundaries, it is possible to obtain a pellet made of a sintered body having low creep resistance near the outer peripheral surface of the pellet. Therefore, there is an effect that there is no need to use a step of adding and mixing a sintering agent into the nuclear fuel powder.

【図面の簡単な説明】[Brief description of the drawings]

【図１】（ａ），（ｂ）は実施例１の方法で製造したペ
レットの中心部および外周面近傍部の結晶構造を示す顕
微鏡写真。1 (a) and 1 (b) are photomicrographs showing the crystal structures of a central portion and a portion near an outer peripheral surface of a pellet produced by the method of Example 1. FIG.

【図２】（ａ），（ｂ）は実施例２の方法で製造したペ
レットの中心部および外周面近傍部の結晶構造を示す顕
微鏡写真。2 (a) and 2 (b) are photomicrographs showing a crystal structure of a central portion and a portion near an outer peripheral surface of a pellet manufactured by the method of Example 2. FIG.

Claims (2)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】核燃料粉末を加圧成形して成形体を形成
し、その成形体の外周面及び端面の少なくとも一方に焼
結助剤を塗布し、その焼結助剤が塗布された成形体を焼
結し、ペレットの外周面近傍の結晶粘界に焼結助剤を析
出させるようにしたことを特徴とする、核燃料ペレット
の製造方法。1. A molded body formed by pressing a nuclear fuel powder under pressure to form a molded body, and applying a sintering aid to at least one of an outer peripheral surface and an end surface of the molded body, and applying the sintering aid to the molded body. And producing a sintering aid in a crystal viscous boundary near an outer peripheral surface of the pellet. 【請求項２】焼結助剤が酸化アルミニウムと二酸化珪素
の混合物或はアルミノケイ酸塩であることを特徴とす
る、請求項１記載の核燃料ペレットの製造方法。2. The method according to claim 1, wherein the sintering aid is a mixture of aluminum oxide and silicon dioxide or an aluminosilicate.
JP10029278A 1998-01-27 1998-01-27 Method for producing nuclear fuel pellets Expired - Fee Related JP2911866B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP10029278A JP2911866B1 (en) 1998-01-27 1998-01-27 Method for producing nuclear fuel pellets

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP10029278A JP2911866B1 (en) 1998-01-27 1998-01-27 Method for producing nuclear fuel pellets

Publications (2)

Publication Number Publication Date
JP2911866B1 true JP2911866B1 (en) 1999-06-23
JPH11211871A JPH11211871A (en) 1999-08-06

Family

ID=12271817

Family Applications (1)

Application Number Title Priority Date Filing Date
JP10029278A Expired - Fee Related JP2911866B1 (en) 1998-01-27 1998-01-27 Method for producing nuclear fuel pellets

Country Status (1)

Country Link
JP (1) JP2911866B1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6581185B2 (en) * 2014-09-08 2019-09-25 ウェスティングハウス エレクトリック スウェーデン アーベー Method for making nuclear fuel pellets for nuclear power reactors
WO2016037712A1 (en) * 2014-09-08 2016-03-17 Westinghouse Electric Sweden Ab Method of making a nuclear fuel pellet for a nuclear power reactor

Also Published As

Publication number Publication date
JPH11211871A (en) 1999-08-06

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