JPH0820534B2 - Manufacturing method of (Mg, U) O2 pellets - Google Patents
Manufacturing method of (Mg, U) O2 pelletsInfo
- Publication number
- JPH0820534B2 JPH0820534B2 JP62016794A JP1679487A JPH0820534B2 JP H0820534 B2 JPH0820534 B2 JP H0820534B2 JP 62016794 A JP62016794 A JP 62016794A JP 1679487 A JP1679487 A JP 1679487A JP H0820534 B2 JPH0820534 B2 JP H0820534B2
- Authority
- JP
- Japan
- Prior art keywords
- pellets
- sintering
- powder
- ratio
- molded body
- 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)
- Manufacture And Refinement Of Metals (AREA)
- Luminescent Compositions (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、核燃料ペレット、特に（Mg,U）O2ペレット
の製法に関するものである。TECHNICAL FIELD The present invention relates to a method for producing nuclear fuel pellets, particularly (Mg, U) O 2 pellets.
（従来の技術） 近年、原子力発電において、燃料の有効利用のため燃
焼度の伸長が考えられているが、この場合、核分裂生成
物（FP）の放出が燃焼度と共に急激に増大し、熱伝導率
が劣化し、燃料温度の上昇、燃料棒内圧の上昇等の不都
合を生じる。そこて、FP特にKr,Xe等のFPガスを燃料ペ
レット内に封じ込める方法が考えられている。（Mg,U）
O2ペレットもその１種であり、Mg添加によって、Ｕイオ
ンの拡散機能を減少させ、ひいてはFPガスの拡散機能を
減少させてペレット内滞留時間を長くすることを狙って
いるものである。(Prior art) In recent years, in nuclear power generation, burnup is expected to increase for effective use of fuel. In this case, however, the release of fission products (FP) increases rapidly with burnup, resulting in heat conduction. Rate deteriorates, causing inconveniences such as an increase in fuel temperature and an increase in fuel rod internal pressure. Therefore, a method of confining FP, particularly FP gas such as Kr or Xe, in the fuel pellet has been considered. (Mg, U)
O 2 pellets are one of them, and the aim is to reduce the diffusion function of U ions and, by extension, the diffusion function of FP gas by adding Mg to prolong the residence time in the pellet.
ところで、UO2ペレットは通常UO2粉末の成型焼結法に
よって製造されるが、この焼結現象はいわゆる固相焼結
であり、ＵイオンあるいはＯイオンの拡散によって焼結
が進行するものである。然るにMgOを添加するとＵイオ
ンの拡散機能が減ずるために、焼結時点において焼結が
なかなか進行せず、高温・長時間焼結が必要であり、ま
た焼結粒径が小さい等の不都合が生じてくる。このため
従来では通常、CO2を主とした微酸化雰囲気での焼結の
後、同温での還元雰囲気で加熱することによりO/M比2.0
になるように調整を行っている。By the way, UO 2 pellets are usually produced by a molding and sintering method of UO 2 powder, and this sintering phenomenon is so-called solid phase sintering, and the sintering progresses by diffusion of U ions or O ions. . However, when MgO is added, the diffusion function of U ions decreases, so that the sintering does not progress easily at the time of sintering, high temperature and long time sintering are required, and there are disadvantages such as a small sintered grain size. Come on. For this reason, conventionally, after sintering in a slightly oxidizing atmosphere mainly containing CO 2 , heating in a reducing atmosphere at the same temperature usually gives an O / M ratio of 2.0.
Is being adjusted.
ここでO/M比について説明を補足すると、Ｏは酸素、
Ｍは金属（Metal）を示し、O/M比は酸素と金属の原子数
比を示す。通常核燃料ペレットは諸特性が安定であるこ
とが要求される。これらの特性はペレットの組成によっ
て変化するので、組成を限定する必要がある。UO2の場
合は通常酸素とウランの原子数比（O/U比で示す）で2.0
とされる。金属添加UO2ではウランと添加金属を合算し
てＭとしO/M比と記される。Here, supplementing the explanation about the O / M ratio, O is oxygen,
M represents a metal, and the O / M ratio represents the atomic ratio of oxygen to the metal. Normally, nuclear fuel pellets are required to have stable characteristics. These properties change with the composition of the pellets, so it is necessary to limit the composition. In the case of UO 2 , the atomic ratio of oxygen to uranium (indicated by O / U ratio) is 2.0.
It is said. In metal-added UO 2 , the sum of uranium and added metal is M, which is expressed as an O / M ratio.
（発明が解決しようとする課題） 以上のような従来技術に鑑み、本発明は特にUO2中に
（Mg,U）O4を添加し、加熱焼結することにより、低温で
しかも特に酸化雰囲気でなくても、Ｕイオンの拡散能を
減少させずに焼結を進行させ、より大きな結晶粒径をも
つMgO添加ペレット、特に（Mg,U）O2系燃料ペレットを
製造する方法を提供することを目的とするものである。(Problems to be Solved by the Invention) In view of the above-described conventional techniques, the present invention particularly adds (Mg, U) O 4 to UO 2 and heat-sinters it to obtain a low temperature and particularly an oxidizing atmosphere. Even if it is not, there is provided a method for producing a MgO-added pellet having a larger crystal grain size, in particular, a (Mg, U) O 2 -based fuel pellet, by promoting sintering without reducing the diffusivity of U ions. That is the purpose.
（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方法はその１つは
（Mg,U）O2ペレットを製造するに、Mgの添加を、UO2粉
末に（Mgx,U1-x）Oy,（０＜ｘ＜1,3≦ｙ≦４）を混合す
ることにより行い、この混合粉末を成型体とし、該成型
体の焼結を還元雰囲気中にて1400℃〜1800℃の温度条件
下にて２時間以上行う方法であり、第２の発明は、上記
成型体の焼結をCO2を含む微酸化雰囲気中にて、1100℃
〜1400℃の温度条件下で0.5時間以上行った後、H2を含
む還元雰囲気中にて1100℃〜1400℃の温度条件下で0.5
時間以上の加熱によりO/M比の調整を行う方法で製造す
ることである。(Means for Solving the Problems) One of the methods of the present invention for solving the above problems is to produce (Mg, U) O 2 pellets by adding Mg to UO 2 powder (Mg x , U 1-x ) Oy, (0 <x <1,3 ≦ y ≦ 4) is mixed, the mixed powder is used as a molded body, and the molded body is sintered at 1400 ° C. in a reducing atmosphere. The second invention is a method of performing the treatment under a temperature condition of 1800 ° C. for 2 hours or more. The second invention is that the molding is sintered at 1100 ° C. in a slightly oxidizing atmosphere containing CO 2.
After 0.5 hour or more at a temperature of ~ 1400 ° C, 0.5 at a temperature of 1100 ° C ~ 1400 ° C in a reducing atmosphere containing H 2.
It is manufactured by a method of adjusting the O / M ratio by heating for more than a time.
（発明の実施の形態） Mgは微量添加した場合、UO2の結晶構造を変形破壊せ
ずに（Mg,U）O2の構造を形成できる。このためUO2の特
性を大きく変更せず目的を達成できる利点がある。同様
な固溶は酸化雰囲気でも生じ、（Mg,U）O4を形成でき
る。(Embodiment of the invention) Mg If slightly added, (Mg, U) the crystal structure without deformation and fracturing of UO 2 structure of O 2 can be formed. Therefore, there is an advantage that the object can be achieved without significantly changing the characteristics of UO 2 . Similar solid solutions also occur in the oxidizing atmosphere and can form (Mg, U) O 4 .
一方、この（Mg,U）O4は高温になると、MgO＋UO3に分
散する特性がある。UO3は更にUO2＋1/2O2となる。On the other hand, this (Mg, U) O 4 has the property of being dispersed in MgO + UO 3 at high temperatures. UO 3 becomes UO 2 + 1 / 2O 2 further.
本発明は上記の点に注目してなされたもので、UO2中
に（Mg,U）O4を添加し、加熱焼結することにより、特に
酸化雰囲気でなくても、内部に酸素供給源をつくり、か
つ、この酸素供給源が焼結阻害因子であるMgOの近傍に
存在することにより阻害能力を減じて、もって、不必要
に高温に加熱せずともＵイオンの拡散能が充分となり、
焼結がスムースに進行されて、より大きな結晶粒をもつ
（Mg,U）O2系燃料ペレットが製造される。The present invention has been made by paying attention to the above points, and by adding (Mg, U) O 4 to UO 2 and heating and sintering, an oxygen supply source can be provided inside even in an oxidizing atmosphere. And the oxygen supply source is present in the vicinity of MgO, which is a sintering inhibiting factor, to reduce the inhibiting ability, so that the U ion diffusing ability becomes sufficient without heating to an unnecessarily high temperature.
Sintering proceeds smoothly to produce (Mg, U) O 2 -based fuel pellets with larger grains.
また、（Mg,U）O4は実際には（Mgx,U1-x）Oyの形態で
あり、ｘとｙはMgの添加率あるいは製造時の酸化条件に
よって０＜ｘ＜１、および３≦ｙ≦４の範囲で変化する
ことができる。一方、UO3やU3O8は現在でも、密度調整
やポア調整のためにUO2に添加して使用されている。従
って最終製品の（Mg,U）O2ペレットのMgの濃度が一定の
場合でも、（Mgx,U1-x）Oyのｘを変化させ添加量を変え
ることにより、密度調整やポア（気孔）調整が可能とな
る利点もある。Further, (Mg, U) O 4 is actually in the form of (Mg x , U 1-x ) Oy, and x and y are 0 <x <1, depending on the addition ratio of Mg or the oxidation conditions at the time of production, and It can be changed within the range of 3 ≦ y ≦ 4. On the other hand, UO 3 and U 3 O 8 are still used in addition to UO 2 for density adjustment and pore adjustment. Therefore, even if the Mg concentration of the (Mg, U) O 2 pellets in the final product is constant, by changing the x of (Mg x , U 1-x ) Oy and changing the addition amount, density adjustment and pore (pore) ) There is also an advantage that adjustment is possible.
なお、焼結は、必ずしも非酸化性雰囲気中にて行わな
ければならないわけではなく、本願第１発明では還元雰
囲気中であるが、第２発明では微酸化性雰囲気中で焼結
を行ってから還元性雰囲気中で加熱してO/M比の調整を
行っている。The sintering does not necessarily have to be performed in a non-oxidizing atmosphere. In the first invention of the present application, the reducing atmosphere is used. However, in the second invention, the sintering is performed in a slightly oxidizing atmosphere. The O / M ratio is adjusted by heating in a reducing atmosphere.
（実施例） 以下、更に本発明の具体的な実施例を示す。(Examples) Specific examples of the present invention will be described below.
（実施例１） Mg化合物とUO2から（Mgx,U1-x）Oyを製造する場合、M
g化合物は微細であることが望ましい。このため、微粉
が得られ易いMgCO3を第１段階の添加物として選択し
た。また反応を促進させるために粒子が接触しているこ
とが望ましいので、MgCO3とUO2粉末を10:90のモル比で
混合後成型体とした後、空気中900℃・３時間の加熱を
行った。この成型体は加熱により粉末となる。また、未
反応物が残るので再度成型加熱を行い、更に成型・加熱
を行った。合計で成型；空気中900℃・３時間加熱を３
回実施したことになる。この後、生成物の安定化のため
に700℃・３時間の加熱を空気中で実施する。以上の加
熱処理により、フリーのMgOやU3O8を殆ど含まない（M
gx,U1-x）Oy（０＜ｘ＜1,3≦ｙ≦４）が得られる。(Example 1) In the case of producing (Mg x , U 1-x ) Oy from a Mg compound and UO 2 , M
It is desirable that the g compound is fine. For this reason, MgCO 3 was selected as the first stage additive because it is easy to obtain fine powder. Since it is desirable that the particles are in contact with each other in order to accelerate the reaction, MgCO 3 and UO 2 powder are mixed at a molar ratio of 10:90 to form a molded body, and then heated in air at 900 ° C for 3 hours. went. This molded body becomes powder by heating. Further, since unreacted substances remain, molding and heating were performed again, and molding and heating were further performed. Molded in total; heated in air at 900 ℃ for 3 hours 3
It has been implemented once. Thereafter, heating at 700 ° C. for 3 hours is carried out in air for stabilizing the product. Due to the above heat treatment, it contains almost no free MgO or U 3 O 8 (M
g x , U 1-x ) Oy (0 <x <1,3 ≦ y ≦ 4) is obtained.
以上の操作によってUO2粉末に添加するMg化合物が得
られる。By the above operation, the Mg compound added to the UO 2 powder can be obtained.
一方、UO2にMgを添加して、大粒径の（Mg,U）O2ペレ
ットを製造する場合、Mgの添加量はMgO換算で50〜100pp
m（重量比）が一般的である。本件の実施例では約70ppm
とした。この場合、製品（Mg,U）O2ペレットにおけるMg
とＵの原子数比はだいたい0.005:1となる。On the other hand, when Mg is added to UO 2 to produce large-sized (Mg, U) O 2 pellets, the amount of Mg added is 50 to 100 pp in terms of MgO.
m (weight ratio) is common. About 70ppm in this example
And In this case, Mg in product (Mg, U) O 2 pellets
And the atomic ratio of U is about 0.005: 1.
従って正確に得られる製品は（Mg0.005 U0.995）O2で
ある。Therefore, the product accurately obtained is (Mg0.005 U0.995) O 2 .
即ち、添加すべきMg化合物（Mgx,U1-x）OyをW1グラム
およびUO2粉末をW2グラムを混合するときに、（W1＋
W2）グラム中のMg原子数とＵ原子数の比が0.005:1とな
るようにW1,W2を決定し、混合するものである。この混
合粉末をプレスにて成型し、成型密度5.90g/cm3の成型
体を得た。That is, when W 1 gram of the Mg compound (Mg x , U 1-x ) Oy to be added and W 2 gram of UO 2 powder are mixed, (W 1 +
W 2 ) W 1 and W 2 are determined and mixed so that the ratio of the number of Mg atoms to the number of U atoms in the gram is 0.005: 1. This mixed powder was molded by a press to obtain a molded body having a molding density of 5.90 g / cm 3 .
この成型条件及び以下に記している焼結条件は通常行
われているUO2ペレットの製造方法と同じである。The molding conditions and the sintering conditions described below are the same as in the usual UO 2 pellet manufacturing method.
この成型体を水蒸気を微量に含む水素・窒素混合気流
中にて1700℃,4時間の焼結を行い、密度94.5％T.D,平均
結晶粒径27μｍの良好な大粒径焼結体を得た。This compact was sintered in a hydrogen / nitrogen mixed gas stream containing a small amount of water vapor at 1700 ° C for 4 hours to obtain a good large grain size sintered body with a density of 94.5% TD and an average crystal grain size of 27 μm. .
（実施例２） 実施例１で製造した成型体を、混合CO2/O2気流中、12
00℃で３時間の焼結を行った後、混合H2/N2気流中、120
0℃で１時間のO/M比の調整を行い、密度93.8％T.D,平均
結晶粒径20μm,O/M比＝2.0の良好な焼結体を得た。(Example 2) The molded body produced in Example 1 was mixed with CO 2 / O 2 in a stream of 12
After sintering at 00 ℃ for 3 hours, in a mixed H 2 / N 2 gas stream, 120
The O / M ratio was adjusted at 0 ° C. for 1 hour to obtain a good sintered body having a density of 93.8% TD, an average crystal grain size of 20 μm, and an O / M ratio of 2.0.
（発明の効果） 本発明は以上、説明したようにMgOを（Mgx,U1-x）Oy
の形態でUO2粉末に添加することにより比較的低温の、
しかも非酸化性雰囲気中での焼結でもＵイオンの拡散能
を阻害することなく焼結を円滑に進行させ、より大きな
結晶粒をもつ（Mg,U）O2ペレットを製造することができ
るほか、最終製品の（Mg,U）O2ペレットのMg濃度が一定
の場合でも、（Mgx,U1-x）Oyのｘを変化させ、添加量を
変えることにより密度調整やポア調整が可能となる効果
を有している。(Effects of the Invention) As described above, the present invention makes MgO (Mg x , U 1-x ) Oy
At a relatively low temperature by adding to the UO 2 powder in the form of
Moreover, even in the case of sintering in a non-oxidizing atmosphere, the sintering can be smoothly proceeded without inhibiting the diffusion ability of U ions, and (Mg, U) O 2 pellets having larger crystal grains can be manufactured. , Even if the Mg concentration of the final product (Mg, U) O 2 pellets is constant, the density and pore can be adjusted by changing the x of (Mg x , U 1-x ) Oy and changing the addition amount. It has the effect of
Claims (2)
加を、UO2粉末に（Mgx,U1-x）Oy,（０＜ｘ＜1,3≦ｙ≦
４）を混合することにより行い、この混合粉末を成型体
とし、該成型体の焼結を還元雰囲気中にて1400℃〜1800
℃の温度条件下にて２時間以上行うことを特徴とする
（Mg,U）O2ペレットの製法。1. To produce (Mg, U) O 2 pellets, Mg is added to UO 2 powder to obtain (Mg x , U 1-x ) Oy, (0 <x <1,3 ≦ y ≦
4) is performed by mixing, and this mixed powder is used as a molded body, and the molded body is sintered in a reducing atmosphere at 1400 ° C to 1800 ° C.
A method for producing (Mg, U) O 2 pellets, which is characterized in that it is carried out at a temperature of ℃ for 2 hours or more.
加を、UO2粉末に（Mgx,U1-x）Oy,（０＜ｘ＜1,3≦ｙ≦
４）を混合することにより行い、この混合粉末を成型体
とし、該成型体の焼結をCO2を含む微酸化雰囲気中に
て、1100℃〜1400℃の温度条件下で0.5時間以上行った
後、H2を含む還元雰囲気中にて1100℃〜1400℃の温度条
件下で0.5時間以上の加熱によりO/M比の調整を行い製造
することを特徴とする（Mg,U）O2ペレットの製法。 2. In order to produce (Mg, U) O 2 pellets, Mg is added to UO 2 powder to obtain (Mg x , U 1-x ) Oy, (0 <x <1,3 ≦ y ≦
4) was mixed, the mixed powder was used as a molded body, and the molded body was sintered in a slightly oxidizing atmosphere containing CO 2 under a temperature condition of 1100 ° C to 1400 ° C for 0.5 hours or more. After that, it is manufactured by adjusting the O / M ratio by heating for 0.5 hours or more under a temperature condition of 1100 ° C to 1400 ° C in a reducing atmosphere containing H 2 (Mg, U) O 2 pellets. Manufacturing method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62016794A JPH0820534B2 (en) | 1987-01-26 | 1987-01-26 | Manufacturing method of (Mg, U) O2 pellets |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62016794A JPH0820534B2 (en) | 1987-01-26 | 1987-01-26 | Manufacturing method of (Mg, U) O2 pellets |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63184092A JPS63184092A (en) | 1988-07-29 |
| JPH0820534B2 true JPH0820534B2 (en) | 1996-03-04 |
Family
ID=11926077
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62016794A Expired - Lifetime JPH0820534B2 (en) | 1987-01-26 | 1987-01-26 | Manufacturing method of (Mg, U) O2 pellets |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0820534B2 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3142598C1 (en) * | 1981-10-27 | 1983-06-09 | Fa. Carl Freudenberg, 6940 Weinheim | Shaped body made of a binding, mineral material and reinforcing fibers embedded in it |
-
1987
- 1987-01-26 JP JP62016794A patent/JPH0820534B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63184092A (en) | 1988-07-29 |
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