JPS6130235B2 - - Google Patents
Info
- Publication number
- JPS6130235B2 JPS6130235B2 JP56141757A JP14175781A JPS6130235B2 JP S6130235 B2 JPS6130235 B2 JP S6130235B2 JP 56141757 A JP56141757 A JP 56141757A JP 14175781 A JP14175781 A JP 14175781A JP S6130235 B2 JPS6130235 B2 JP S6130235B2
- Authority
- JP
- Japan
- Prior art keywords
- lithium
- ammonium oxalate
- added
- sintering
- density
- 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
Links
- VBIXEXWLHSRNKB-UHFFFAOYSA-N ammonium oxalate Chemical compound [NH4+].[NH4+].[O-]C(=O)C([O-])=O VBIXEXWLHSRNKB-UHFFFAOYSA-N 0.000 claims description 41
- 238000005245 sintering Methods 0.000 claims description 37
- 239000008188 pellet Substances 0.000 claims description 32
- 238000000034 method Methods 0.000 claims description 14
- FCTBKIHDJGHPPO-UHFFFAOYSA-N uranium dioxide Inorganic materials O=[U]=O FCTBKIHDJGHPPO-UHFFFAOYSA-N 0.000 claims description 13
- 239000003758 nuclear fuel Substances 0.000 claims description 11
- OOAWCECZEHPMBX-UHFFFAOYSA-N oxygen(2-);uranium(4+) Chemical compound [O-2].[O-2].[U+4] OOAWCECZEHPMBX-UHFFFAOYSA-N 0.000 claims description 11
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 10
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 claims description 5
- 229910001947 lithium oxide Inorganic materials 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 5
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 4
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 claims description 4
- 150000002642 lithium compounds Chemical class 0.000 claims description 3
- YNQRWVCLAIUHHI-UHFFFAOYSA-L dilithium;oxalate Chemical compound [Li+].[Li+].[O-]C(=O)C([O-])=O YNQRWVCLAIUHHI-UHFFFAOYSA-L 0.000 claims description 2
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 claims description 2
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 2
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 2
- 230000001590 oxidative effect Effects 0.000 claims description 2
- UTDLAEPMVCFGRJ-UHFFFAOYSA-N plutonium dihydrate Chemical compound O.O.[Pu] UTDLAEPMVCFGRJ-UHFFFAOYSA-N 0.000 claims description 2
- FLDALJIYKQCYHH-UHFFFAOYSA-N plutonium(IV) oxide Inorganic materials [O-2].[O-2].[Pu+4] FLDALJIYKQCYHH-UHFFFAOYSA-N 0.000 claims description 2
- 239000000843 powder Substances 0.000 description 23
- 150000001875 compounds Chemical class 0.000 description 13
- 239000011148 porous material Substances 0.000 description 13
- 229910018068 Li 2 O Inorganic materials 0.000 description 11
- 230000000694 effects Effects 0.000 description 11
- 239000002245 particle Substances 0.000 description 7
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 6
- 229910052744 lithium Inorganic materials 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 239000000314 lubricant Substances 0.000 description 5
- 238000000465 moulding Methods 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 238000000879 optical micrograph Methods 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 239000000654 additive Substances 0.000 description 2
- 238000000280 densification Methods 0.000 description 2
- 230000004992 fission Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- FVCDUAYRTFOPHK-UHFFFAOYSA-M C(C(=O)[O-])(=O)[O-].[NH4+].[Li+] Chemical compound C(C(=O)[O-])(=O)[O-].[NH4+].[Li+] FVCDUAYRTFOPHK-UHFFFAOYSA-M 0.000 description 1
- 229910013553 LiNO Inorganic materials 0.000 description 1
- 229910001093 Zr alloy Inorganic materials 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 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
Landscapes
- Monitoring And Testing Of Nuclear Reactors (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Description
【発明の詳細な説明】
本発明は原子炉燃料用酸化物（UO2およびＵ，
Puの混合酸化物、特にUO2）のペレツトの焼結法
に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention provides oxides for nuclear reactor fuel (UO 2 and U,
This invention relates to a method for sintering pellets of mixed oxides of Pu, especially UO 2 ).
周知のように、通常の原子炉の核燃料において
は二酸化ウランの焼結ペレツトをジルカロイ等の
被覆管に充填したものが原子燃料要素として使用
されている。 As is well known, in nuclear fuel for ordinary nuclear reactors, sintered pellets of uranium dioxide filled in a cladding tube such as Zircaloy are used as the nuclear fuel element.
この場合、該ペレツトは、UO2粉末を原料と
し、（粗成形）→（造粒）→（潤滑剤の添加）→
成形→1600℃ないし1700℃以上の温度での焼結の
工程（（ ）に入れた過程は省略されることもあ
る）によつて製造されている。 In this case, the pellets are made from UO 2 powder and are processed by (rough molding) → (granulation) → (addition of lubricant) →
It is manufactured by a process of molding → sintering at a temperature of 1,600℃ to 1,700℃ or higher (the steps in parentheses may be omitted).
これらのペレツトには次の諸性質が要求され
る。 These pellets are required to have the following properties:
(1) 焼結体が全体として理論値の90％以上の密度
を有すること。(1) The sintered body as a whole has a density of 90% or more of the theoretical value.
(2) 照射（燃焼）初期の緻密化（焼きしまり）の
程度を小にし、かつ核分裂生成物の保留能を増
大させるため、UO2の平均結晶粒径が可及的に
大であること。(2) The average grain size of UO 2 should be as large as possible in order to reduce the degree of densification (hardening) at the initial stage of irradiation (combustion) and increase the ability to retain fission products.
(3) なるべく低温で焼結できること。(3) Must be able to sinter at as low a temperature as possible.
(4) 照射（燃焼）時の寸法安定化のため、焼結体
中に20〜40μの空孔が均一に分布しており、マ
トリツクスの密度が可及的に高く、理想的には
マトリツクスの密度が理論値に等しく、残余が
空孔によつて占められていること。(4) In order to stabilize the dimensions during irradiation (combustion), pores of 20 to 40μ are uniformly distributed in the sintered body, and the density of the matrix is as high as possible. The density is equal to the theoretical value, with the remainder occupied by vacancies.
このうち、(1)と(3)の目的を達成するために、従
来種々の研究が行なわれており、例えば原料の
UO2粉末の活性化、焼結雰囲気の改善、添加物の
使用が試みられてきた。 Among these, in order to achieve the objectives (1) and (3), various researches have been conducted in the past, such as research on raw materials.
Attempts have been made to activate UO2 powder, improve the sintering atmosphere, and use additives.
(2)の目的のためには、UO2にNb化合物を添加
して焼結を行なうことが研究されている。 For the purpose of (2), research has been conducted on adding Nb compounds to UO 2 to perform sintering.
(4)の目的のためには特開昭49−101795、特開昭
49−101796に開示されているようにシユウ酸アン
モニウムを添加して焼結することが有効であるこ
とが知られている。 For the purpose of (4), Japanese Patent Application Laid-Open No. 49-101795,
It is known that sintering with the addition of ammonium oxalate as disclosed in No. 49-101796 is effective.
最近本発明者等はUO2に少量のLi化合物を添加
して焼結することにより、(1)，(2)，(3)の目的を可
なり高度に達成できることを見出し、それに基づ
く発明に対して特許出願した（特願昭56−6292、
特願昭 − ）。 Recently, the present inventors have discovered that the objectives (1), (2), and (3) can be achieved to a fairly high degree by adding a small amount of Li compound to UO 2 and sintering it, and have developed an invention based on this. (Patent application 1986-6292,
Tokugansho-).
本発明者等は当該発明の方法に前記シユウ酸ア
ンモニウム添加の手法を併用することを試みたと
ころ、良好な結果が得られ、本発明を完成した。 The inventors of the present invention attempted to use the method of adding ammonium oxalate described above in combination with the method of the present invention, obtained good results, and completed the present invention.
本発明によれば二酸化ウラニウムおよび／また
は二酸化プルトニウムの圧粉体を非酸化性雰囲気
中で焼結することにより核燃料ペレツトを製造す
る方法において、核圧粉体にリチウム化合物およ
びシユウ酸アンモニウムを含有させて焼結するこ
とを特徴とする核燃料ペレツトの製造法が提供さ
れる。 According to the present invention, in a method for producing nuclear fuel pellets by sintering a green compact of uranium dioxide and/or plutonium dioxide in a non-oxidizing atmosphere, the nuclear green compact contains a lithium compound and ammonium oxalate. A method for producing nuclear fuel pellets is provided, which comprises sintering nuclear fuel pellets.
即ち特開昭49−101795、同49−101796の方法で
は焼結密度と空孔サイズの制御は可能であるが、
結晶粒径の制御は不可能で、かつ高温度における
焼結を必要とした。特願昭56−6292の方法では、
焼結密度と結晶粒径の制御が可能であり、かつ比
較的低温で焼結できるが、空孔サイズの制御は不
可能であつた。本発明方法によれば、焼結密度、
結晶粒径、空孔サイズのすべてを制御でき、かつ
低温で焼結できる。 In other words, although it is possible to control the sintered density and pore size with the methods of JP-A-49-101795 and JP-A-49-101796,
Control of grain size was not possible and required sintering at high temperatures. In the method of patent application No. 56-6292,
Although it is possible to control the sintered density and grain size, and sinter at relatively low temperatures, it has been impossible to control the pore size. According to the method of the present invention, the sintered density,
Both crystal grain size and pore size can be controlled, and sintering can be performed at low temperatures.
本発明において使用される核燃料酸化物は主と
してUO2であるが、前述のようにMOXとよばれ
るUO2とPUO2との混合酸化物であつてもよく、
そのことは理論的に当業者によつて認められよ
う。 The nuclear fuel oxide used in the present invention is mainly UO 2 , but as mentioned above, it may also be a mixed oxide of UO 2 and PUO 2 called MOX,
This will be theoretically recognized by those skilled in the art.
UO2粉末は化学量論的関係からずれていてもよ
いが、ずれている必要もなく、通常の方法によつ
て得られるものでよい。 Although the UO 2 powder may deviate from the stoichiometric relationship, it is not necessary to deviate from the stoichiometric relationship and may be obtained by a conventional method.
添加するLi化合物はLi2O，LiOH，Li2CO3，
LiNO3，Liのハロゲン化物、酢酸リチウム、シユ
ウ酸リチウム等のLiを含有しているものなら何で
も使用できる。安価で好ましいものはLi2O，
LiOH等であり、その添加量はUO2に対して単体
リチウムに換算して0.002〜0.5％である。0.002％
未満では本発明の目的を達成し難く、0.5％以上
加えてもその添加の効果は飽和し、ペレツト中に
残存するLi濃度が高くなり核燃料として好ましく
ない結果をもたらすことが予想される。 The Li compounds added are Li 2 O, LiOH, Li 2 CO 3 ,
Anything containing Li, such as LiNO 3 , Li halides, lithium acetate, and lithium oxalate, can be used. Cheap and preferable Li 2 O,
LiOH, etc., and the amount added is 0.002 to 0.5% in terms of elemental lithium based on UO 2 . 0.002%
If it is less than 0.5%, it will be difficult to achieve the purpose of the present invention, and even if it is added in an amount of 0.5% or more, the effect of addition will be saturated, and it is expected that the concentration of Li remaining in the pellet will increase, resulting in unfavorable results as a nuclear fuel.
本発明において、焼結する雰囲気は通常H2ガ
スであるが、他にH2／N2混合ガスまたは真空雰
囲気下であつても、得られる焼結体の特性に特に
顕著な差はなく、いずれの雰囲気においても良好
な結果が得られる。 In the present invention, the sintering atmosphere is usually H 2 gas, but even if it is in an H 2 /N 2 mixed gas or vacuum atmosphere, there is no noticeable difference in the properties of the obtained sintered body. Good results can be obtained in any atmosphere.
圧粉体（グリーンペレツト）の成形条件に特に
制限はなく、Liを添加混合した二酸化ウラン粉末
を金型に充填し、所定の圧力で成形する方法であ
る。 There are no particular restrictions on the molding conditions for the compact (green pellet), and the method is to fill a mold with uranium dioxide powder mixed with Li and mold it under a predetermined pressure.
焼結温度に関しては従来の例ではすでに述べた
ように工業的には少なくとも1600℃以上通常1700
℃以上であつた。本発明の方法において、特定の
焼結密度を達成するための焼結温度は、Li化合物
およびシユウ酸アンモニウムの添加量によつて異
なり、Liの添加量を増すほどその温度は低下す
る。また特定の結晶粒径を得るための焼結温度は
Liの添加量によつて異なり、Liの添加量を増すほ
どその温度は低下する。しかしながら、焼結密度
および結晶粒度への効果におよぼすLi添加量の影
響は添加量の少ない時に顕著であり、添加量が多
くなるにつれて飽和する傾向にある。 Regarding the sintering temperature, as already mentioned in conventional examples, industrially it is at least 1600℃ or higher and usually 1700℃.
It was over ℃. In the method of the present invention, the sintering temperature for achieving a specific sintered density varies depending on the amount of Li compound and ammonium oxalate added, and the temperature decreases as the amount of Li added increases. Also, the sintering temperature to obtain a specific grain size is
The temperature varies depending on the amount of Li added, and the temperature decreases as the amount of Li added increases. However, the influence of the amount of Li added on the effects on the sintered density and grain size is significant when the amount added is small, and tends to become saturated as the amount added increases.
本発明において、このようにLi化合物を二酸化
ウラン粉末に添加することにより、従来よりも低
い温度で焼結密度を高めることが出来、同時に結
晶粒度の粗大化が得られるが、一方Liの添加量を
増すことおよび焼結温度を低下することは、結果
的に焼結体中に残存するLi含有量を多くする。
UO2焼結体中に残存するLi量が多くなることは単
に不純物量の増加という観点から定性的に好まし
くなく、定量的数値制限が設定し得ない現段階に
おいては、なるべく残存Li量は少ないことが好ま
しい。 In the present invention, by adding a Li compound to the uranium dioxide powder in this way, it is possible to increase the sintered density at a lower temperature than before, and at the same time coarsen the grain size, but on the other hand, the amount of Li added Increasing the sintering temperature and lowering the sintering temperature result in an increase in the Li content remaining in the sintered body.
An increase in the amount of Li remaining in the UO 2 sintered body is qualitatively undesirable from the perspective of simply increasing the amount of impurities, and at this stage, where quantitative numerical limits cannot be set, the amount of remaining Li should be kept as low as possible. It is preferable.
なお、焼結時間については特に制限はなく、経
験的または実験的に容易に定めることができる。
通常の温度条件下では約２時間程度である。 Note that the sintering time is not particularly limited and can be easily determined empirically or experimentally.
Under normal temperature conditions, it takes about 2 hours.
以上の条件は特願昭56−6292（特開昭 −
）に実証されている。 The above conditions apply to Japanese Patent Application No. 56-6292.
) has been proven.
シユウ酸アンモニウムを二酸化ウランに添加し
てその焼結体中の空孔率を調節する一般的な方法
は特開昭49−101795および特開昭49−101796に記
載されている。本発明においては、シユウ酸アン
モニウムは微粉末状のもので、前記Li化合物と同
時に二酸化ウラン粉末と混合される。シユウ酸ア
ンモニウムの粒子サイズは10〜100μの範囲と
し、好ましくは20〜40μとする。シユウ酸アンモ
ニウムの粒子サイズは空孔サイズに影響するが、
空孔がUO2焼結体の寸法安定化に寄与するにはシ
ユウ酸アンモニウムの粒子サイズが10μ以下では
生成する空孔サイズが小さすぎ、100μ以上では
大きすぎるからである。 A general method of adding ammonium oxalate to uranium dioxide to control the porosity in the sintered body is described in JP-A-49-101795 and JP-A-49-101796. In the present invention, ammonium oxalate is in the form of a fine powder, and is mixed with the uranium dioxide powder at the same time as the Li compound. The particle size of ammonium oxalate is in the range 10-100μ, preferably 20-40μ. Particle size of ammonium oxalate affects pore size;
This is because if the particle size of ammonium oxalate is 10μ or less, the pore size generated is too small, and if it is 100μ or more, the pore size is too large for the pores to contribute to the dimensional stabilization of the UO 2 sintered body.
シユウ酸アンモニウムの二酸化ウランに対する
添加量は0.1〜６重量％とし、好ましくは0.2〜３
重量％とする。シユウ酸アンモニウムの二酸化ウ
ランに対する添加量は焼結体密度に影響を及ぼ
す。シユウ酸アンモニウムの添加量が増すに従つ
て、一般に焼結体密度は低下する。しかしながら
焼結体密度は焼結温度、焼結時間およびLi化合物
の添加量の影響も受け、これらの値が大きいほど
密度は高くなる。従つて焼結体の理論密度（T.
D.）の90％以上の焼結体を得るためのシユウ酸
アンモニウム添加量は焼結温度、焼結時間および
Li化合物の添加量等によつて異る。 The amount of ammonium oxalate added to uranium dioxide is 0.1 to 6% by weight, preferably 0.2 to 3% by weight.
Weight%. The amount of ammonium oxalate added to uranium dioxide affects the density of the sintered body. Generally, as the amount of ammonium oxalate added increases, the density of the sintered body decreases. However, the density of the sintered body is also affected by the sintering temperature, sintering time, and amount of Li compound added, and the larger these values are, the higher the density is. Therefore, the theoretical density of the sintered body (T.
D.) The amount of ammonium oxalate added to obtain a sintered body of 90% or more is determined by the sintering temperature, sintering time and
It varies depending on the amount of Li compound added.
本発明において、このようにLi化合物とシユウ
酸アンモニウムを二酸化ウラン粉末に添加するこ
とにより、均質径の空孔が均一に分布し、空孔以
外の部分焼結密度が高く、結晶粒径の大きな焼結
体を従来よりも低い焼結温度で得ることができ
る。その際、Li化合物はシユウ酸アンモニウムの
空孔生成作用に何ら影響を与えることなく、また
シユウ酸アンモニウムはLi化合物の焼結促進効果
を何ら妨害することがない。 In the present invention, by adding the Li compound and ammonium oxalate to the uranium dioxide powder, pores with a uniform diameter are uniformly distributed, the partial sintering density other than the pores is high, and the crystal grain size is large. A sintered body can be obtained at a lower sintering temperature than conventionally. At this time, the Li compound does not have any effect on the pore-generating effect of ammonium oxalate, and ammonium oxalate does not interfere with the sintering promotion effect of the Li compound.
次に図面を参照して、本発明を具体的に説明す
る。以下の記載において％はすべて重量％であ
る。 Next, the present invention will be specifically described with reference to the drawings. In the following description, all percentages are by weight.
第１図は平均粒径約0.7μ（沈降法による）の
UO2粉末に、潤滑剤として0.2％のステアリン酸
亜鉛を添加し、さらに20〜40μに整粒したシユウ
酸アンモニウムを０，0.2，0.5，1.0％添加したも
の、およびその各々にリチウム成分として、リチ
ウム換算で0.05％に相当する水酸化リチウム、炭
酸リチウム、フツ化リチウム、塩化リチウムおよ
びシユウ酸リチウムアンモニウムを添加したもの
を金型を用いて3t／cm2の圧力で直径10mm、高さ15
mmの圧粉体（グリーンペレツト）としたもの（重
さ約７ｇ）を水素気流中で1400℃、２時間かけて
焼結したUO2ペレツトのシユウ酸アンモニウム添
加量と焼結密度及び平均結晶粒径の関係を示す。 Figure 1 shows an average particle size of approximately 0.7μ (according to the sedimentation method).
0.2% zinc stearate was added as a lubricant to UO 2 powder, and 0, 0.2, 0.5, and 1.0% of ammonium oxalate sized to 20 to 40 μ were added, and each of them had a lithium component. Added lithium hydroxide, lithium carbonate, lithium fluoride, lithium chloride, and lithium ammonium oxalate equivalent to 0.05% in terms of lithium were added using a mold at a pressure of 3t/cm 2 with a diameter of 10mm and a height of 15mm.
The amount of ammonium oxalate added, the sintered density, and the average crystallinity of UO 2 pellets, which were made into green pellets (weighing about 7 g) and sintered in a hydrogen stream at 1400℃ for 2 hours. Shows the relationship between particle sizes.
第２図は上記シユウ酸アンモニウム無添加のペ
レツトの組織を示すペレツト断面の光学顕微鏡写
真である。第３図は上記シユウ酸アンモニウムを
0.5％添加したペレツトの組織を示すペレツト断
面の光学顕微鏡写真である。黒点が空孔である。 FIG. 2 is an optical micrograph of a cross section of the pellet showing the structure of the pellet without the addition of ammonium oxalate. Figure 3 shows the above ammonium oxalate.
It is an optical micrograph of a cross section of a pellet showing the structure of a pellet added at 0.5%. The black dots are holes.
第４図は平均粒径約0.7μのUO2粉末に、潤滑
剤として0.2％のステアリン酸亜鉛を添加し、さ
らにこれにLi2Oと（NH4）2C2O4をそれぞれ0.1％
および1.0％添加したもの、Li2Oのみを0.1％添加
したもの、（NH4）2C2O4のみを0.5％添加したも
の、Li2Oと（NH4）2C2O4のいずれも添加しない
ものを調整し、金型を用いて3t／cm2の圧力でこれ
らを直径10mm、高さ15mmの圧粉体（重さ約７ｇ）
としたものを、水素気流中で種々の温度で焼結し
たUO2ペレツトの焼結温度と焼結密度の関係を示
す。 Figure 4 shows UO 2 powder with an average particle size of approximately 0.7μ, 0.2% zinc stearate as a lubricant, and 0.1% each of Li 2 O and (NH 4 ) 2 C 2 O 4 added to this.
and 1.0%, 0.1% of Li 2 O only, 0.5% of (NH 4 ) 2 C 2 O 4 only, and both Li 2 O and (NH 4 ) 2 C 2 O 4 Using a mold, we prepared powders that did not contain any additives and pressed them into a compact with a diameter of 10 mm and a height of 15 mm (weighing approximately 7 g) using a mold at a pressure of 3 t/cm 2 .
The relationship between sintering temperature and sintered density of UO 2 pellets sintered at various temperatures in a hydrogen stream is shown.
第１図から明らかなように、シユウ酸アンモニ
ウムの添加量が増すに従つて焼結体密度（実線と
左側の縦座標で示される）は直線的に減少する。
これは添加したシユウ酸アンモニウムがその分解
温度でガス化して除去され、UO2ペレツト中に空
孔を残すからである。例えばシユウ酸アンモニウ
ムを添加していないペレツトの焼結体密度はその
理論密度の92.0％であつたが、シユウ酸アンモニ
ウムを二酸化ウランに対して0.5％添加した焼結
体の密度は理論密度の89.9％であつた。従つて、
0.5％のシユウ酸アンモニウムの添加によつて約
２％分の空孔が新たに発生したことになる。 As is clear from FIG. 1, the sinter density (indicated by the solid line and the left ordinate) decreases linearly as the amount of ammonium oxalate added increases.
This is because the added ammonium oxalate is gasified and removed at its decomposition temperature, leaving vacancies in the UO 2 pellet. For example, the density of a sintered body of pellets without ammonium oxalate added was 92.0% of its theoretical density, but the density of a sintered body with 0.5% ammonium oxalate added to uranium dioxide was 89.9% of its theoretical density. It was %. Therefore,
By adding 0.5% ammonium oxalate, approximately 2% of vacancies were newly generated.
また第１図から明らかなように、平均結晶粒径
（点線と右側の縦座標によつて示される）はLi化
合物の添加によつて増加するが、それはシユウ酸
アンモニウムの添加によつて影響されない。 It is also evident from Figure 1 that the average grain size (indicated by the dotted line and the right ordinate) increases with the addition of Li compounds, but it is not affected by the addition of ammonium oxalate. .
第２図に示す通り、シユウ酸アンモニウム無添
加のUO2ペレツトは細かい黒点として見える数μ
以下の空孔が多数散在する。これらの空孔は一般
に不安定であつて、照射（燃焼）によつてたやす
く除去され緻密化がすすむことが知られている。
一方、第３図にみられる通り、0.5％のシユウ酸
アンモニウムを添加して得られたUO2ペレツトの
断面には20〜40μ径の空孔が均一に分布してい
る。これらの空孔がUO2ペレツトに存在すると、
UO2ペレツトが原子炉条件下で核分裂生成物によ
る膨張および放射線による緻密化の両方を受けて
も、UO2ペレツトは著しい寸法安定性を示す。 As shown in Figure 2, UO 2 pellets without ammonium oxalate have a few micrometers visible as fine black dots.
Many of the following vacancies are scattered. It is known that these pores are generally unstable and are easily removed and densified by irradiation (combustion).
On the other hand, as seen in FIG. 3, pores with a diameter of 20 to 40 μm are uniformly distributed in the cross section of the UO 2 pellet obtained by adding 0.5% ammonium oxalate. When these vacancies exist in UO2 pellets,
UO 2 pellets exhibit remarkable dimensional stability even though they undergo both fission product expansion and radiation densification under reactor conditions .
第４図から明らかな通り、Li2Oの0.1％（Li換
算0.047％）添加によつて焼結体の密度は増大
し、その増加割合は比較的低い焼結温度の時に顕
著である。Li2Oの添加の効果はシユウ酸アンモ
ニウムの添加の有無に影響されない。同じく、第
４図において（図中A.O.とあるはシユウ酸アン
モニウム）、シユウ酸アンモニウムを1.0％添加し
たUO2ペレツトの焼結密度は無添加の場合に比し
て、Li2Oの添加の有無や焼結温度と無関係に、
一律に平均約４％減少している。このことは
（NH4）2C2O4はLi2Oの焼結促進効果を何ら妨害す
ることなく、またLi2Oは（NH4）2C2O4の空孔形
成作用に何の影響も及ぼさないことを示す。従つ
て、本発明のLi化合物とシユウ酸アンモニウムを
添加して得られる核燃料ペレツトは巨視的には20
〜40μの空孔が均一に分布するため密度が低い
が、マトリツクス部分の密度は高く、結晶粒が大
きい。 As is clear from FIG. 4, the density of the sintered body increases by adding 0.1% (Li equivalent: 0.047%) of Li 2 O, and the rate of increase is remarkable at a relatively low sintering temperature. The effect of Li 2 O addition is not affected by the presence or absence of ammonium oxalate addition. Similarly, in Fig. 4 (AO in the figure stands for ammonium oxalate), the sintered density of UO 2 pellets with 1.0% ammonium oxalate added is different from that of the case without the addition of Li 2 O. Regardless of the temperature and sintering temperature,
It has decreased by about 4% on average across the board. This means that (NH 4 ) 2 C 2 O 4 does not interfere with the sintering promotion effect of Li 2 O, and Li 2 O has no effect on the pore-forming effect of (NH 4 ) 2 C 2 O 4 . Indicates that it has no effect. Therefore, the nuclear fuel pellets obtained by adding the Li compound of the present invention and ammonium oxalate have a macroscopic size of 20
The density is low because the ~40μ pores are uniformly distributed, but the density in the matrix part is high and the crystal grains are large.
以下、本発明の方法の好適実施例を示す。 Hereinafter, preferred embodiments of the method of the present invention will be shown.
実施例 １
平均粒径0.7μｍのUO2粉末に潤滑剤として0.2
重量％のステアリン酸亜鉛を添加し、該原料粉末
を金型を用いて3t／cm2の圧力で直径10mm、高さ15
mmの圧粉体としたものを水素気流中で1250℃、
1400℃、1550℃、1700℃の各温度にてそれぞれ２
時間焼結した。各温度における焼結により得られ
るUO2の焼結体密度はそれぞれ理論密度の78.8
％、92.0％、96.5％、97.8％であつた。また顕微
鏡により観察される焼結体の平均結晶粒径はそれ
ぞれ＜３μ，５μ，９μ，17μであつた。（第４
図の〓〓線）
上記方法は通常のUO2焼結体製造法である。上
述したと同じUO2粉末に0.2重量％のステアリン
酸亜鉛、0.1重量％の酸化リチウム（単体リチウ
ム換算0.047重量％）、1.0重量％のシユウ酸アン
モニウム粉末（20〜40μに整粒）を添加・混合し
た。該原料粉末を上述したと同様に成形・焼結し
て得られる焼結体の密度および平均結晶粒径はそ
れぞれの焼結温度に対応して理論密度の92.5％、
93.8％、94.5％、94.8％；25μ，65μ，95μ，170
μであつた。（第４図の〓〓〓線。）
実施例 ２
実施例１と同じUO2粉末に潤滑剤として0.2重
量％のステアリン酸亜鉛を添加し、該原料粉末を
実施例１と同様の方法で成形し、1200℃の温度で
２時間焼結した。得られた焼結体の密度は理論密
度の71.5％であり、平均結晶粒径は３μ以下であ
つた。Example 1 UO 2 powder with an average particle size of 0.7 μm was added with 0.2 μm as a lubricant.
% by weight of zinc stearate was added, and the raw material powder was molded into a mold with a diameter of 10 mm and a height of 15 mm under a pressure of 3 t/cm 2.
mm compacted powder at 1250℃ in a hydrogen stream.
2 at each temperature of 1400℃, 1550℃, and 1700℃
Sintered for hours. The sintered body density of UO 2 obtained by sintering at each temperature is 78.8 of the theoretical density.
%, 92.0%, 96.5%, and 97.8%. The average crystal grain sizes of the sintered bodies observed under a microscope were <3μ, 5μ, 9μ, and 17μ, respectively. (4th
(–– line in the figure) The above method is a normal UO 2 sintered body manufacturing method. To the same UO 2 powder as described above, 0.2% by weight of zinc stearate, 0.1% by weight of lithium oxide (0.047% by weight in terms of simple lithium), and 1.0% by weight of ammonium oxalate powder (sized to 20 to 40 μ) were added. Mixed. The density and average grain size of the sintered body obtained by molding and sintering the raw material powder in the same manner as described above are 92.5% of the theoretical density,
93.8%, 94.5%, 94.8%; 25μ, 65μ, 95μ, 170
It was μ. (〓〓〓〓 line in Figure 4.) Example 2 0.2% by weight of zinc stearate was added as a lubricant to the same UO 2 powder as in Example 1, and the raw material powder was molded in the same manner as in Example 1. and sintered at a temperature of 1200°C for 2 hours. The density of the obtained sintered body was 71.5% of the theoretical density, and the average grain size was 3 μm or less.
上述したと同じUO2粉末に0.2重量％のステア
リン酸亜鉛、0.1重量％の酸化リチウム（単体リ
チウム換算0.047重量％）、0.5重量％のシユウ酸
アンモニウムを添加・混合した。該原料粉末を上
述と同じ条件で成形・焼結して得られる焼結体の
密度および平均結晶粒径は、それぞれ理論密度の
93.6％、20μであつた。 To the same UO 2 powder as described above, 0.2% by weight of zinc stearate, 0.1% by weight of lithium oxide (0.047% by weight in terms of simple lithium), and 0.5% by weight of ammonium oxalate were added and mixed. The density and average grain size of the sintered body obtained by molding and sintering the raw material powder under the same conditions as above are the theoretical density.
It was 93.6% and 20μ.
実施例 ３
実施例１に示した同一のUO2粉末に0.2重量％
のステアリン酸亜鉛、0.01重量％の酸化リチウム
（単体リチウム換算0.0047重量％）、１重量％のシ
ユウ酸アンモニウムを添加し、該原料粉末を実施
例１と同じ方法で成形し、1550℃、1700℃の各温
度でそれぞれ２時間焼結した。各温度における焼
結により得られた焼結体の密度および平均結晶粒
径はそれぞれ理論密度の93.5％、94.6％；55μ，
75μであつた。なお、上述した酸化リチウムおよ
びシユウ酸アンモニウムを添加しない時の焼結密
度および平均結晶粒径は実施例１に示した同じ値
となり、それぞれ理論密度の96.5％，97.8％；９
μ，17μであつた。Example 3 0.2% by weight of the same UO 2 powder shown in Example 1
of zinc stearate, 0.01% by weight of lithium oxide (0.0047% by weight in terms of simple lithium), and 1% by weight of ammonium oxalate, the raw material powder was molded in the same manner as in Example 1, and heated at 1550°C and 1700°C. Sintering was performed at each temperature for 2 hours. The density and average grain size of the sintered body obtained by sintering at each temperature were 93.5% and 94.6% of the theoretical density, respectively; 55μ,
It was 75μ. The sintered density and average grain size when the above-mentioned lithium oxide and ammonium oxalate are not added are the same values as shown in Example 1, which are 96.5% and 97.8% of the theoretical density, respectively.
It was 17μ.
第１図はUO2ペレツトのシユウ酸アンモニウム
添加量と焼結体密度および平均結晶粒径との関係
を示す。第２図はシユウ酸アンモニウム無添加の
UO2ペレツト断面の光学顕微鏡写真を示す。第３
図はシユウ酸アンモニウムを0.5％添加したUO2
ペレツト断面の光学顕微鏡写真を示す。第４図は
UO2ペレツトの焼結体密度におよぼすLi2Oとシ
ユウ酸アンモニウムの添加の効果を焼結温度との
関係で示す。
FIG. 1 shows the relationship between the amount of ammonium oxalate added to UO 2 pellets, the density of the sintered body, and the average grain size. Figure 2 shows the product without ammonium oxalate.
An optical micrograph of a cross section of a UO 2 pellet is shown. Third
The figure shows UO 2 with 0.5% ammonium oxalate added.
An optical micrograph of a cross section of the pellet is shown. Figure 4 is
The effects of the addition of Li 2 O and ammonium oxalate on the sintered density of UO 2 pellets are shown in relation to the sintering temperature.
Claims (1)
トニウムの圧粉体を非酸化性雰囲気中で焼結する
ことにより核燃料ペレツトを製造する方法におい
て、核圧粉体にリチウム化合物およびシユウ酸ア
ンモニウムを含有させて焼結することを特徴とす
る核燃料ペレツトの製造法。 ２ リチウム化合物が酸化リチウム、水酸化リチ
ウム、炭酸リチウム、酢酸リチウム、シユウ酸リ
チウム、フツ化リチウムおよび塩化リチウムから
なる群から選ばれる少なくとも１種である特許請
求の範囲第１項記載の方法。 ３ 焼結温度が1200℃以上である特許請求の範囲
第１項および第２項記載の方法。[Claims] 1. A method for producing nuclear fuel pellets by sintering a green compact of uranium dioxide and/or plutonium dioxide in a non-oxidizing atmosphere, in which a lithium compound and ammonium oxalate are added to the green compact. 1. A method for producing nuclear fuel pellets, characterized by containing the pellets and sintering the pellets. 2. The method according to claim 1, wherein the lithium compound is at least one selected from the group consisting of lithium oxide, lithium hydroxide, lithium carbonate, lithium acetate, lithium oxalate, lithium fluoride, and lithium chloride. 3. The method according to claims 1 and 2, wherein the sintering temperature is 1200°C or higher.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56141757A JPS5844394A (en) | 1981-09-10 | 1981-09-10 | Method of making nuclear fuel pellet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56141757A JPS5844394A (en) | 1981-09-10 | 1981-09-10 | Method of making nuclear fuel pellet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5844394A JPS5844394A (en) | 1983-03-15 |
| JPS6130235B2 true JPS6130235B2 (en) | 1986-07-11 |
Family
ID=15299480
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56141757A Granted JPS5844394A (en) | 1981-09-10 | 1981-09-10 | Method of making nuclear fuel pellet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5844394A (en) |
-
1981
- 1981-09-10 JP JP56141757A patent/JPS5844394A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5844394A (en) | 1983-03-15 |
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