JP2786345B2 - Method for producing nuclear fuel pellet and nuclear fuel pellet - Google Patents
Method for producing nuclear fuel pellet and nuclear fuel pelletInfo
- Publication number
- JP2786345B2 JP2786345B2 JP3177050A JP17705091A JP2786345B2 JP 2786345 B2 JP2786345 B2 JP 2786345B2 JP 3177050 A JP3177050 A JP 3177050A JP 17705091 A JP17705091 A JP 17705091A JP 2786345 B2 JP2786345 B2 JP 2786345B2
- Authority
- JP
- Japan
- Prior art keywords
- nuclear fuel
- sintering
- pellet
- fuel pellet
- pellets
- 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 - Lifetime
Links
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
- Compositions Of Oxide Ceramics (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、核燃料ペレットの製造
方法および核燃料ペレットに係り、特に核燃料の高燃焼
度化に対応して改善された核燃料ペレットの製造方法お
よび核燃料ペレットに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing nuclear fuel pellets and nuclear fuel pellets, and more particularly to a method for producing nuclear fuel pellets and an improved nuclear fuel pellet corresponding to high burnup of nuclear fuel.
【０００２】[0002]
【従来の技術】従来から軽水炉、高速増殖炉に装荷され
る核燃料ペレットは、発電炉において経験された最も高
い燃焼度までその健全性が確認されている。しかし、現
在計画されている燃料の高燃焼度化に伴って、結晶粒界
に析出した核分裂生成ガス（ＦＰガス）による気泡スエ
リングの増加に伴ってペレットと被覆管の機械的相互作
用（ＰＣＩ）の増大、燃料からのＦＰガス放出による燃
料棒内の内圧の上昇が起こり、燃料の健全性が失われる
可能性があり、現在のペレットを改善する必要がある。2. Description of the Related Art Conventionally, the soundness of nuclear fuel pellets loaded in a light water reactor or a fast breeder reactor has been confirmed up to the highest burnup experienced in a power reactor. However, with the increase in fuel burnup currently planned, the swelling of bubbles by fission product gas (FP gas) precipitated at grain boundaries increases the mechanical interaction (PCI) between the pellet and cladding tube. And the internal pressure in the fuel rods increases due to the release of FP gas from the fuel, which may lead to a loss of fuel integrity. Therefore, it is necessary to improve the current pellets.
【０００３】そこで、従来はペレットからのＦＰガス放
出率がＦＰガスのペレット結晶粒内の拡散に律速される
と考え、ペレットの結晶粒径を大きくすることによっ
て、ＦＰガスの放出率を抑える方法が試みられてきた。Conventionally, it is considered that the FP gas release rate from the pellet is determined by the diffusion of the FP gas in the crystal grains of the pellet, and the emission rate of the FP gas is suppressed by increasing the crystal grain size of the pellet. Have been tried.
【０００４】しかし、結晶粒径を大きくするとペレット
のクリ−プ速度が低下し、ＰＣＩに悪影響を与える。一
方、ペレットのクリ−プ速度を向上させる方法として、
二酸化ウラン粉末にアルミニウム酸化物とケイ素酸化物
とからなる焼結剤を添加し、結晶粒界に軟質第二相を析
出させる方法として、（１）特開平１−１９３６９１号
公報、（２）特開平２−２４２１９５号公報があり、そ
れぞれ焼結剤の添加総量は約０．１〜１．０ｗｔ％、
０．０５〜０．４％としている。[0004] However, when the crystal grain size is increased, the creep speed of the pellet is reduced, which adversely affects PCI. On the other hand, as a method of improving the creep speed of the pellet,
As a method of adding a sintering agent composed of aluminum oxide and silicon oxide to uranium dioxide powder to precipitate a soft second phase at a crystal grain boundary, there are disclosed in (1) Japanese Patent Application Laid-Open No. 1-193691 and (2) Japanese Unexamined Patent Publication No. Hei 2-242195 discloses that the total amount of the sintering agent added is about 0.1 to 1.0 wt%,
0.05 to 0.4%.
【０００５】[0005]
【発明が解決しようとする課題】核燃料の高燃焼度化に
伴い焼結密度が大きく、熱伝導率の大きなペレットが望
まれている。ところが、上記のように従来の割合でアル
ミニウム酸化物とケイ素酸化物からなる焼結剤を添加す
ると、ペレット内に気孔（ケイ素酸化物の蒸発によると
推定）を生成し、ペレットの焼結密度が大きくならない
ことが判った。さらに、結晶粒径を２０μｍ以上にする
のに要する焼結剤の添加量は約１０ｐｐｍ以上であり、
かつ５００ｐｐｍ以上では有意差が無いことが判った。With the increase in burnup of nuclear fuel, pellets having a high sintering density and a high thermal conductivity are desired. However, when a sintering agent composed of aluminum oxide and silicon oxide is added at a conventional ratio as described above, pores (estimated due to evaporation of silicon oxide) are generated in the pellet, and the sintered density of the pellet is reduced. It turned out not to grow. Further, the addition amount of the sintering agent required to make the crystal grain size 20 μm or more is about 10 ppm or more,
And it was found that there was no significant difference at 500 ppm or more.
【０００６】本発明はかかる問題に対処してなされたも
ので、その目的は、ペレットの焼結密度および結晶粒径
が大きく、かつクリ−プ特性を向上させることができる
ＵＯ2燃料ペレット製造方法およびペレットを提供する
ことにある。SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to provide a method for producing UO 2 fuel pellets in which the sintered density and crystal grain size of the pellets are large and the creep characteristics can be improved. And pellets.
【０００７】[0007]
【課題を解決するための手段】上記課題を解決するため
の本発明の核燃料ペレットの製造方法は、ＵＯ2 粉末を
圧縮成形した後、これを焼結して核燃料ペレットを製造
する方法において、約４０〜８０Ｗ％のＳｉＯ2 と残部
のＡｌ2Ｏ3とからなる組成を有する焼結剤を合計量の１
０〜４００ｐｐｍの割合でＵＯ2粉末に混合した後、圧
縮成形し、約１５００〜１８００℃の焼結温度で焼結す
るようにしたことである。The method for producing nuclear fuel pellets of the present invention for solving the above-mentioned problems comprises a method for producing nuclear fuel pellets by compressing UO 2 powder and then sintering it. 40～80W% of 1 of the total amount of the sintering agent having a composition consisting of SiO 2 and the balance of Al 2 O 3 Metropolitan
After mixing the UO 2 powder in a proportion of from 0 to 400 ppm, compression molding, is that which is adapted to sinter at a sintering temperature of about 1500 to 1800 ° C..
【０００８】また、上記課題を解決するための本発明の
核燃料ペレットの構成は、そのＵＯ2粒子が約２０〜６
０μｍの平均結晶粒径を有し、その結晶粒界のほとんど
がガラス状もしくは結晶質性のアルミナシリケ−ト相で
被覆され、かつその気孔率は約１〜４ｖｏｌ％のように
したことである。[0008] The structure of the nuclear fuel pellet of the present invention for solving the above-mentioned problem is such that the UO 2 particles are about 20 to 6 particles.
It has an average grain size of 0 μm, most of its grain boundaries are coated with a glassy or crystalline alumina silicate phase, and its porosity is about 1 to 4 vol%.
【０００９】[0009]
【作用】本発明の製造方法に従ってペレットを製造する
と、焼結中に上記の焼結剤が一液相の共融体となり、液
相焼結メカニズムによって核燃料粉末間の表面反応を促
進し、緻密化および結晶粒の成長を助長する。このよう
なＵＯ2燃料を用いることにより熱伝導率が増大し、か
つＦＰガスの結晶粒界への拡散距離が増加し、ペレット
からのＦＰガス放出率が低下する。When pellets are produced according to the production method of the present invention, the above-mentioned sintering agent becomes a eutectic in one liquid phase during sintering, and the surface reaction between nuclear fuel powders is promoted by a liquid phase sintering mechanism, and the And promote crystal growth. By using such a UO 2 fuel, the thermal conductivity increases, the diffusion distance of the FP gas to the crystal grain boundaries increases, and the FP gas release rate from the pellets decreases.
【００１０】また、上記焼結剤の１部は、焼結中に蒸発
しペレット外に放出されるが、他は結晶粒界に第二相と
して析出する。この析出相は比較的低い融点を有するた
め、軟化温度が低く、ペレットのクリ−プ速度を向上さ
せ、耐ＰＣＩ性を向上させることになる。A part of the sintering agent evaporates during the sintering and is discharged outside the pellet, while the other part is precipitated as a second phase at the crystal grain boundaries. Since the precipitated phase has a relatively low melting point, the softening temperature is low, the creep speed of the pellet is improved, and the PCI resistance is improved.
【００１１】本発明において、アルミニウム酸化物とケ
イ素酸化物からなる焼結剤を、核燃料体の全重量を基準
として約１０〜５００ｐｐｍの割合としたのは、結晶粒
径を２０μｍ以上にするのに焼結剤を約１０ｐｐｍ以上
必要とすること、また５００ｐｐｍ以上の添加量では有
意な差が無いことが実験結果から確かめられたからであ
る。さらに、５００ｐｐｍ以上添加することは、無意味
なばかりでなく、ペレットの密度を小さくするという逆
効果を示した。その逆効果を避けるためにも、最大添加
量を５００ｐｐｍとする必要があった。In the present invention, the ratio of the sintering agent composed of aluminum oxide and silicon oxide to about 10 to 500 ppm based on the total weight of the nuclear fuel body is used to make the crystal grain size 20 μm or more. This is because it was confirmed from the experimental results that the sintering agent required about 10 ppm or more, and that there was no significant difference in the addition amount of 500 ppm or more. Further, the addition of 500 ppm or more was not only meaningless, but also exhibited an adverse effect of reducing the density of the pellet. In order to avoid the adverse effect, the maximum addition amount had to be set to 500 ppm.
【００１２】[0012]
【実施例】以下本発明の核燃料ペレットの製造方法の１
実施例を図面を用いて説明する。図１は本発明の実施例
の核燃料ペレットの製造工程図である。以下の製造工程
を流れにしたがってせ説明する。図１において、１はＵ
Ｏ2粉末、２は焼結剤、３は混合工程、４は成形工程、
５はグリ−ンペレット、６は焼結工程、７は焼結ペレッ
トである。DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method 1 of the present invention for producing nuclear fuel pellets will be described.
Embodiments will be described with reference to the drawings. FIG. 1 is a view showing a manufacturing process of nuclear fuel pellets according to an embodiment of the present invention. The following manufacturing process will be described according to the flow. In FIG. 1, 1 is U
O 2 powder, 2 is a sintering agent, 3 is a mixing step, 4 is a molding step,
5 is a green pellet, 6 is a sintering step, and 7 is a sintered pellet.
【００１３】まず、酸化アルミニウム（Ａｌ2Ｏ3）４０
ｗｔ％と酸化ケイ素（ＳｉＯ2）６０ｗｔ％とを粗混合
し、これを８％−Ｈ2／Ｎ2混合ガス気流中で２１００℃
まで加熱して溶融させた後冷却し、均質なアルミナシリ
ケ−トを得た。これを粉砕して均一な粉末とした。この
混合粉末を焼結剤２とした。First, aluminum oxide (Al 2 O 3 ) 40
wt% and 60 wt% of silicon oxide (SiO 2 ) were roughly mixed, and this was mixed at 2100 ° C. in an 8% -H 2 / N 2 mixed gas stream.
After heating to melt, the mixture was cooled to obtain a homogeneous alumina silicate. This was pulverized into a uniform powder. This mixed powder was used as a sintering agent 2.
【００１４】ＵＯ2粉末１に上記焼結剤２を、核燃料体
の全重量を基準として約３０〜５００ｐｐｍ添加し、混
合３した後、圧粉成形４して、グリ−ンペレット５を製
造した。このグリ−ンペレット５を水素雰囲気中で１７
３０℃、３時間焼結することにより、製品の焼結ペレッ
ト７を得た。The sintering agent 2 was added to the UO 2 powder 1 in an amount of about 30 to 500 ppm based on the total weight of the nuclear fuel body, mixed 3 and then compacted 4 to produce green pellets 5. This green pellet 5 is placed in a hydrogen atmosphere for 17 hours.
By sintering at 30 ° C. for 3 hours, a sintered pellet 7 of the product was obtained.
【００１５】以上の方法により製造した核燃料ペレット
において、焼結剤２の添加量を、３０、２５０、５００
ｐｐｍの他に０（添加せず）および２５００ｐｐｍ
（０．２５ｗｔ％）とした場合のそれぞれについて得ら
れた焼結密度および平均結晶粒径の値を一括して表示し
た。In the nuclear fuel pellets manufactured by the above-described method, the amount of the sintering agent 2 added is set to 30, 250, 500
0 (no addition) and 2500 ppm in addition to ppm
(0.25 wt%), the values of the sintered density and the average crystal grain size obtained for each of them are collectively displayed.
【表】 【table】
【００１６】表からわかるように、添加量０の場合は、
添加量３０〜５００ｐｐｍの場合に比べて焼結密度およ
び平均結晶粒径共にかなり小さい。また、添加量２５０
０ｐｐｍにした場合にも平均結晶粒径はよいが、焼結密
度はむしろ小さくなることを示している。すなわち、焼
結剤の添加量は３０〜５００ｐｐｍの範囲にした場合が
最も有効であることが実証された。As can be seen from the table, when the addition amount is 0,
Both the sintered density and the average crystal grain size are considerably smaller than in the case where the addition amount is 30 to 500 ppm. In addition, addition amount 250
Even when 0 ppm is set, the average crystal grain size is good, but the sintered density is rather small. That is, it was proved that the case where the addition amount of the sintering agent was in the range of 30 to 500 ppm was most effective.
【００１７】前記の方法により製造した核燃料ペレット
は、ＵＯ2粒子は２０〜６０μｍの平均結晶粒径を有
し、その結晶粒界のほとんどがガラス状もしくは結晶質
性のアルミナシリケ−ト相で被覆され、かつその気孔率
は約１〜４ｖｏｌ％である。なお、前記実施例では、焼
結剤としてアルミナシリケ−トを用いたが、酸化アルミ
ニウム粉末と酸化ケイ素粉末の混合粉末を用いてもよ
い。In the nuclear fuel pellets produced by the above method, the UO 2 particles have an average crystal grain size of 20 to 60 μm, and most of the crystal grain boundaries are coated with a glassy or crystalline alumina silicate phase. And its porosity is about 1-4 vol%. In the above embodiment, alumina silicate was used as the sintering agent, but a mixed powder of aluminum oxide powder and silicon oxide powder may be used.
【００１８】[0018]
【発明の効果】本発明の製造方法により、高燃焼度化に
対応できる核燃料ペレットを得ることができるようにな
った。本核燃料ペレットを用いれば、熱伝導率および結
晶粒径が大きいことから燃料中心温度を低くすることが
でき、また、ＦＰガスの結晶粒界への拡散距離が増加
し、ペレットからのＦＰガス放出率が低下する。さら
に、結晶粒界に軟化温度の低い第２相を有するため、ペ
レットのクリ−プ速度を向上させ、耐ＰＣＩ性を向上さ
せる効果がある。According to the production method of the present invention, it has become possible to obtain nuclear fuel pellets which can cope with high burnup. The use of the present nuclear fuel pellets makes it possible to lower the fuel center temperature because of its large thermal conductivity and crystal grain size, and also increases the diffusion distance of the FP gas to the crystal grain boundaries, thereby releasing FP gas from the pellets. The rate drops. Further, since the crystal phase has the second phase having a low softening temperature at the grain boundaries, it has an effect of improving the creep speed of the pellet and improving the PCI resistance.
【図１】本発明の実施例の核燃料ペレットの製造工程図
である。FIG. 1 is a manufacturing process diagram of a nuclear fuel pellet according to an embodiment of the present invention.
１ ＵＯ2粉末 ２ 焼結剤 ３ 混合工程 ４ 成形工程 ５ グリ−ンペレット ６ 焼結工程 ７ 焼結ペレット1 UO 2 powder 2 sintering agent 3 Mixing Step 4 forming step 5 glyceraldehyde - Nperetto 6 sintering step 7 sintered pellets
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平２−242195（ＪＰ，Ａ) 特開 平１−193691（ＪＰ，Ａ) 特開 平２−236490（ＪＰ，Ａ) 特開 平１−201190（ＪＰ，Ａ) 特開 平１−201191（ＪＰ，Ａ) ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-242195 (JP, A) JP-A-1-193691 (JP, A) JP-A-2-236490 (JP, A) JP-A-1- 201190 (JP, A) JP-A-1-201191 (JP, A)
Claims (2)
して核燃料ペレットを製造する方法において、約４０〜
８０Ｗ％のＳｉＯ2 と残部のＡｌ2Ｏ3とからなる組成を
有する焼結剤を合計量の１０〜４００ｐｐｍの割合でＵ
Ｏ2粉末に混合した後、圧縮成形し、約１５００〜１８
００℃の焼結温度で焼結することを特徴とする核燃料ペ
レットの製造方法。1. A method for producing nuclear fuel pellets by compressing UO 2 powder and then sintering the powder.
A sintering agent having a composition consisting of 80 W% of SiO 2 and the balance of Al 2 O 3 is added at a ratio of 10 to 400 ppm of the total amount of U.
After mixing the O 2 powder, compression molding, about 1500-18
A method for producing nuclear fuel pellets, comprising sintering at a sintering temperature of 00 ° C.
燃料ペレット。2. A nuclear fuel pellet produced by the production method according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3177050A JP2786345B2 (en) | 1991-07-18 | 1991-07-18 | Method for producing nuclear fuel pellet and nuclear fuel pellet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3177050A JP2786345B2 (en) | 1991-07-18 | 1991-07-18 | Method for producing nuclear fuel pellet and nuclear fuel pellet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0527069A JPH0527069A (en) | 1993-02-05 |
| JP2786345B2 true JP2786345B2 (en) | 1998-08-13 |
Family
ID=16024263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3177050A Expired - Lifetime JP2786345B2 (en) | 1991-07-18 | 1991-07-18 | Method for producing nuclear fuel pellet and nuclear fuel pellet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2786345B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019231046A1 (en) * | 2018-05-29 | 2019-12-05 | 한전원자력연료 주식회사 | Uranium dioxide pellets having excellent fission gas adsorbing property and manufacturing method therefor |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4869866A (en) * | 1987-11-20 | 1989-09-26 | General Electric Company | Nuclear fuel |
| JPH0731265B2 (en) * | 1989-03-15 | 1995-04-10 | 原子燃料工業株式会社 | Manufacturing method of nuclear fuel pellets |
-
1991
- 1991-07-18 JP JP3177050A patent/JP2786345B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0527069A (en) | 1993-02-05 |
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