JPH0915373A - Method for measuring quantity of compaction of fuel pellet - Google Patents
Method for measuring quantity of compaction of fuel pelletInfo
- Publication number
- JPH0915373A JPH0915373A JP7162117A JP16211795A JPH0915373A JP H0915373 A JPH0915373 A JP H0915373A JP 7162117 A JP7162117 A JP 7162117A JP 16211795 A JP16211795 A JP 16211795A JP H0915373 A JPH0915373 A JP H0915373A
- Authority
- JP
- Japan
- Prior art keywords
- test
- pellets
- shrinkage
- compaction
- amount
- 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
- 239000008188 pellet Substances 0.000 title claims abstract description 33
- 238000000034 method Methods 0.000 title claims description 13
- 239000000446 fuel Substances 0.000 title claims description 10
- 238000005056 compaction Methods 0.000 title abstract 4
- 239000011261 inert gas Substances 0.000 claims abstract description 6
- CMIHHWBVHJVIGI-UHFFFAOYSA-N gadolinium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[Gd+3].[Gd+3] CMIHHWBVHJVIGI-UHFFFAOYSA-N 0.000 claims description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 10
- 239000001301 oxygen Substances 0.000 abstract description 10
- 229910052760 oxygen Inorganic materials 0.000 abstract description 10
- 239000013078 crystal Substances 0.000 abstract description 9
- 239000007789 gas Substances 0.000 abstract description 9
- 238000000280 densification Methods 0.000 abstract description 8
- 238000010438 heat treatment Methods 0.000 abstract description 8
- 230000003247 decreasing effect Effects 0.000 abstract description 2
- 238000000926 separation method Methods 0.000 abstract 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 8
- 239000001257 hydrogen Substances 0.000 description 8
- 229910052739 hydrogen Inorganic materials 0.000 description 8
- 238000003795 desorption Methods 0.000 description 6
- 238000007796 conventional method Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 1
- 229910001938 gadolinium oxide Inorganic materials 0.000 description 1
- 229940075613 gadolinium oxide Drugs 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000003758 nuclear fuel Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 230000004580 weight loss Effects 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)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、酸化ガドリニウム（Ｇ
ｄ２Ｏ３）を含有するＵＯ２焼結ペレットの加熱前後の
密度差から焼きしまり量を求める方法に関する。The present invention relates to gadolinium oxide (G
The present invention relates to a method for determining the amount of shrinkage from the difference in density of UO 2 sintered pellets containing d 2 O 3 ) before and after heating.
【０００２】[0002]
【従来の技術】軽水炉あるいは高速増殖炉に装荷される
核燃料ペレットは、高密度化されていると共に、高燃焼
度化に伴い熱中性子の吸収を促進するためにガドリニウ
ム（Ｇｄ）の添加量が増えている。酸化ガドリニウム
（Ｇｄ２Ｏ３）を含有するＵＯ２焼結ペレットは、操業
中に焼きしまり（デンシフィケーション）現象が生じ
る。焼きしまりは酸化物ペレットが照射中に収縮する現
象であって、１０００℃以下の低温で生じることや１
０，０００ＭＷｄ／ｔまでの低燃焼度で観察され、ペレ
ットの焼結過程で見られるような熱的な収縮とは区別さ
れる。2. Description of the Related Art Nuclear fuel pellets loaded in a light water reactor or a fast breeder reactor are highly densified, and the amount of gadolinium (Gd) added is increased in order to accelerate the absorption of thermal neutrons as the burnup increases. ing. UO 2 sintered pellets containing gadolinium oxide (Gd 2 O 3 ) undergo a phenomenon of densification during operation. The shrinkage is a phenomenon in which oxide pellets shrink during irradiation, which occurs at a low temperature of 1000 ° C. or less.
Observed at low burnups up to 20,000 MWd / t, distinct from the thermal shrinkage seen in the pellet sintering process.
【０００３】従来、焼きしまり量の測定方法としては、
ＵＯ２ペレットで行われているように乾水素雰囲気中に
て、ガドリニア添加ペレットを１７００〜１７２５℃の
温度で２４時間加熱し、加熱試験前後の密度差から焼き
しまり量を求める方法がある。しかし、ガドリニアを多
く含むペレットの焼きしまり試験では、負の焼きしまり
量、すなわち加熱後の密度が加熱前よりも小さくなる後
退現象、を生ずることがある。これは乾水素中での高温
加熱のため、 （Ｕ１−ａＧｄａ）Ｏ２→（Ｕ１−ａ、Ｇｄａ）Ｏ
２−ａ／２ の反応を生じ、結晶格子中の酸素離脱によりＯ／Ｍが低
下して、試験後に重量変化、直径変化の焼きしまり以外
の挙動が生じるためである。Conventionally, as a method for measuring the amount of shrinkage,
There is a method in which gadolinia-added pellets are heated at a temperature of 1700 to 1725 ° C. for 24 hours in a dry hydrogen atmosphere as is the case with UO 2 pellets, and the amount of shrinkage is determined from the density difference before and after the heating test. However, in the shrinkage test of pellets containing a large amount of gadolinia, a negative shrinkage amount, that is, a recession phenomenon in which the density after heating becomes smaller than that before heating may occur. Since this is a high temperature heating in dry hydrogen, (U 1-a Gd a ) O 2 → (U 1-a , Gd a ) O
This is because the reaction of 2-a / 2 occurs and O / M decreases due to the desorption of oxygen in the crystal lattice, and a behavior other than burning due to weight change and diameter change occurs after the test.
【０００４】これに代る焼きしまり量を測定する従来方
法としては、ＵＯ２単体の乾水素中に比較して湿水素中
で焼きしまり試験をする方法がある。この方法は、試験
雰囲気中の酸素ポテンシャルを上げ、ＵＯ２とＧｄ２Ｏ
３の固溶体の結晶格子中の酸素の離脱を防ぐことを目的
としている。しかし、この方法は、実炉内は通常、水
素コントロール下にあるため、炉内挙動を模擬する雰囲
気としては適切でない、湿水素中の水分は炉ヒータ
ー、炉リフレクター等に悪影響を及ぼす、湿水素水分
量によって焼きしまり量が影響を受ける、等の問題があ
る。As an alternative conventional method for measuring the amount of shrinkage, there is a method of performing a shrinkage test in wet hydrogen as compared with dry hydrogen of UO 2 simple substance. This method raises the oxygen potential in the test atmosphere to increase UO 2 and Gd 2 O.
The purpose is to prevent the release of oxygen in the crystal lattice of the solid solution of No. 3 . However, this method is not suitable as an atmosphere for simulating the behavior inside the furnace because the inside of the actual furnace is usually under hydrogen control. Moisture in wet hydrogen adversely affects the furnace heater, the reflector, etc. There is a problem that the amount of baking is affected by the amount of water.
【０００５】焼きしまり量の測定は、加熱保持試験前後
の密度差から求める。酸素離脱による重量の減少、格子
定数の増加した試験後のペレットは、酸化離脱がないペ
レットと比較して密度が低くなり、結果として負の焼き
しまり量を示すことになる。このように、従来法による
測定では、ガドリニア添加ペレットの正常なデンシフィ
ケーション値は得られない問題がある。The amount of shrinkage is determined from the difference in density before and after the heat retention test. The pellets after the test, in which the weight is decreased due to the oxygen desorption and the lattice constant is increased, have a lower density than the pellets without the oxidation desorption, and as a result, the amount of the negative baking is shown. As described above, the conventional method has a problem that a normal densification value of the gadolinia-added pellet cannot be obtained.
【０００６】[0006]
【発明が解決しようとする課題】本発明は、Ｇｄ添加燃
料ペレットの焼きしまり量の測定において、ＵＯ２とＧ
ｄ２Ｏ３固溶体のＯ／Ｍが変化することなく、すなわち
結晶格子中の酸素の離脱による重量の減少や格子定数の
増加することなく、焼きしまり量を測定するための試験
条件を設定することを目的としている。DISCLOSURE OF THE INVENTION The present invention, in measuring the amount of shrinkage of Gd-added fuel pellets, uses UO 2 and G
To set the test conditions for measuring the amount of shrinkage without changing the O / M of the d 2 O 3 solid solution, that is, without reducing the weight or increasing the lattice constant due to the desorption of oxygen in the crystal lattice. It is an object.
【０００７】[0007]
【課題を解決するための手段】本発明者らは、Ｇｄ添加
の燃料ペレットの焼きしまり試験において負の焼きしま
り量が生じるのは、結晶格子中の酸素が減少することに
よる格子定数の増加、すなわち膨張および単位体積当た
りの重量の減少にあることを見い出した。そこで、本発
明者らは、これらの知見に基づき焼きしまり試験の雰囲
気として不活性ガス雰囲気を選択し、これにより焼きし
まり現象のみの良好な試験結果を得ることが出来たので
ある。Means for Solving the Problems The inventors of the present invention have found that a negative sintering amount in a sintering test of a Gd-added fuel pellet is caused by an increase in lattice constant due to a decrease in oxygen in the crystal lattice, That is, they were found to be swelling and weight loss per unit volume. Therefore, the inventors of the present invention have selected an inert gas atmosphere as the atmosphere for the shrinkage test based on these findings, and have been able to obtain good test results only for the shrinkage phenomenon.
【０００８】本発明は、下記の事項をその要旨としてい
る。酸化ガドリニウム（Ｇｄ２Ｏ３）を１．０〜１５．
０重量％含むＵＯ２ペレット又は（Ｐｕ、Ｕ）Ｏ２ペレ
ットの焼きしまり試験において、Ｏ／Ｍを変化させるこ
となく、下記の試験条件で行うことを特徴とする燃料ペ
レットの焼きしまり量測定方法。 加熱保持温度：１７００〜１７５０℃ 昇温時間および降温時間：９０〜１２０分 加熱保持時間：２４時間 試験雰囲気：不活性ガス雰囲気 焼きしまり量算出：試験前後の密度の差The gist of the present invention is as follows. Gadolinium oxide (Gd 2 O 3 ) 1.0 to 15.
In a burn-in test of UO 2 pellets or (Pu, U) O 2 pellets containing 0% by weight, the burn-in amount measurement method for fuel pellets is performed under the following test conditions without changing O / M. . Heating / holding temperature: 1700 to 1750 ° C. Temperature rising / falling time: 90 to 120 minutes Heating / holding time: 24 hours Test atmosphere: Inert gas atmosphere Calculation of shrinkage: Difference in density before and after the test
【０００９】以下に、本発明を詳細に説明する。燃料ペ
レットの焼きしまりに伴って、線出力密度の増加、
軸方向ギャップの形成による出力スパイク、軸方向ギ
ャップ部での被覆管のつぶれ、直径ギャップの増加に
よる燃料温度の増加、など操業中の問題が生じる。Hereinafter, the present invention will be described in detail. Increase in linear power density due to burning of fuel pellets,
Operational problems such as power spikes due to the formation of axial gaps, crushing of cladding at the axial gaps, and increased fuel temperature due to increased diameter gaps occur.
【００１０】焼きしまりを評価するには、通常、ペレッ
トやスタックの寸法変化、密度変化、気孔の消滅や収縮
などが測定される。また、実験パラメータとしては、
ペレット燃焼条件（温度、時間）、初期密度、結晶
粒径、気孔径分布、照射条件（燃焼度、線出力）な
どが選ばれる。In order to evaluate shrinkage, dimensional changes of pellets and stacks, changes in density, disappearance and shrinkage of pores are usually measured. As experimental parameters,
Pellet combustion conditions (temperature, time), initial density, crystal grain size, pore size distribution, irradiation conditions (burnup, linear output), etc. are selected.
【００１１】本発明のペレットの焼きしまり量測定方法
の試験条件と、従来法のそれとの比較を、表１に示す。Table 1 shows a comparison between the test conditions of the method for measuring the amount of shrinkage of pellets of the present invention and that of the conventional method.
【００１２】[0012]
【表１】 [Table 1]
【００１３】従来の方法は、乾水素雰囲気中で、ガス圧
が０．３５ｋｇ／ｃｍ2 、ガス露点は−７０〜−５５
℃、温度１７００〜１７５０℃、試験時間２４時間で測
定している。このような試験条件では、下記の反応、 （Ｕ１−ａ、Ｇｄａ）Ｏ２→（Ｕ１−ａ、Ｇｄａ）Ｏ
２−ａ／２ を生じ、結晶格子中の酸素離脱が起り、その結果負の焼
きしまり量を示すこととなる。The conventional method has a gas pressure of 0.35 kg / cm 2 and a gas dew point of -70 to -55 in a dry hydrogen atmosphere.
C., temperature 1700 to 1750.degree. C., and test time 24 hours. Under such test conditions, the following reaction: (U 1-a , Gd a ) O 2 → (U 1-a , Gd a ) O
2-a / 2 occurs, oxygen desorption in the crystal lattice occurs, and as a result, a negative amount of shrinkage is exhibited.
【００１４】本発明の測定方法は、不活性ガス雰囲気中
で、ガス圧が０．３５ｋｇ／ｃｍ2、ガス露点−５５〜
４０℃、試験温度１７００〜１７５０℃、試験時間２４
時間で測定するものであり、試験ガス雰囲気として不活
性ガスを使用すること、およびガスの露点温度が上昇し
ている点において特徴を有している。In the measuring method of the present invention, the gas pressure is 0.35 kg / cm 2 and the gas dew point is −55 to −55 in an inert gas atmosphere.
40 ° C, test temperature 1700 to 1750 ° C, test time 24
It is measured by time, and is characterized in that an inert gas is used as a test gas atmosphere and the dew point temperature of the gas is increased.
【００１５】[0015]
【実施例】以下に、本発明を実施例により具体的に説明
する。Ｇｄ２Ｏ３を含有する燃料ペレットの焼きしまり
量を測定するに際し、本発明方法と比較例の試験条件
を、表２に示す。The present invention will be described below in more detail with reference to examples. Table 2 shows the test conditions of the method of the present invention and the comparative example when measuring the amount of shrinkage of the fuel pellet containing Gd 2 O 3 .
【００１６】[0016]
【表２】 [Table 2]
【００１７】表２に示す条件で焼きしまり試験をしたと
きのデンシフィケーション値と初期焼結密度との関係
を、図１に示す。FIG. 1 shows the relationship between the densification value and the initial sintered density when a shrinkage test was conducted under the conditions shown in Table 2.
【００１８】図１に示すように、比較例である乾水素を
用いた場合はＧｄ２Ｏ３濃度が７．５〜１０重量％と高
くなる（記号●）につれて、デンシフィケーション値が
低くなり、ついには０点を越えて負の値を示すようにな
る。一方、本発明のＨｅガス雰囲気ではＧｄ２Ｏ３濃度
が５重量％以下と低く（記号△）ても、７．５〜１０重
量％と高く（記号□）てもデンシフィケーション値は、
常にプラスの領域に存在している。As shown in FIG. 1, when dry hydrogen which is a comparative example is used, the densification value decreases as the Gd 2 O 3 concentration increases to 7.5 to 10% by weight (symbol ●). Eventually, it will go beyond 0 and show a negative value. On the other hand, in the He gas atmosphere of the present invention, even if the Gd 2 O 3 concentration is as low as 5 wt% or less (symbol Δ) or as high as 7.5 to 10 wt% (symbol □), the densification value is
It is always in the positive realm.
【００１９】[0019]
【発明の効果】本発明により、燃料ペレットの結晶格子
中の酸素離脱現象が抑えられ、デンシフィケーション値
が正常値を示す。これにより、焼きしまり変動の少な
い、品質の良い燃料ペレットが得られる。According to the present invention, the oxygen desorption phenomenon in the crystal lattice of the fuel pellet is suppressed, and the densification value shows a normal value. This makes it possible to obtain high-quality fuel pellets with less variation in shrinkage.
【図１】焼きしまり試験をしたときのデンシフィケーシ
ョン値と初期焼結密度との関係を示したグラフである。FIG. 1 is a graph showing a relationship between a densification value and an initial sintered density when a shrinkage test is performed.
Claims (1)
〜１５．０重量％含むＵＯ２ペレット又は（Ｐｕ、Ｕ）
Ｏ２ペレットの焼きしまり量を測定する方法であって、
Ｏ／Ｍを変化させないように、下記の試験条件で行うこ
とを特徴とする、燃料ペレットの焼きしまり量測定方
法。 試験温度：１７００〜１７５０℃ 昇温時間および降温時間：９０〜１２０分 試験時間：２４時間 試験雰囲気：不活性ガス雰囲気 焼きしまり量算出：試験前後の密度の差1. Gadolinium oxide (Gd 2 O 3 ) 1.0
~ 15.0 wt% UO 2 pellets or (Pu, U)
A method for measuring the amount of tightness of O 2 pellets, comprising:
A method for measuring the amount of shrinkage of fuel pellets, which is carried out under the following test conditions so as not to change O / M. Test temperature: 1700 to 1750 ° C Temperature raising and lowering time: 90 to 120 minutes Test time: 24 hours Test atmosphere: Inert gas atmosphere Calculation of amount of shrinkage: Difference in density before and after the test
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7162117A JP3025422B2 (en) | 1995-06-28 | 1995-06-28 | Method for measuring the amount of burning of fuel pellets |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7162117A JP3025422B2 (en) | 1995-06-28 | 1995-06-28 | Method for measuring the amount of burning of fuel pellets |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0915373A true JPH0915373A (en) | 1997-01-17 |
| JP3025422B2 JP3025422B2 (en) | 2000-03-27 |
Family
ID=15748370
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7162117A Expired - Fee Related JP3025422B2 (en) | 1995-06-28 | 1995-06-28 | Method for measuring the amount of burning of fuel pellets |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3025422B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6583677B2 (en) | 2000-10-12 | 2003-06-24 | Sharp Kabushiki Kaisha | Oscillator and an oscillator characteristic adjustment method |
-
1995
- 1995-06-28 JP JP7162117A patent/JP3025422B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6583677B2 (en) | 2000-10-12 | 2003-06-24 | Sharp Kabushiki Kaisha | Oscillator and an oscillator characteristic adjustment method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3025422B2 (en) | 2000-03-27 |
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