JP2000147186A - Method for testing gadolinia-added uranium dioxide pellet - Google Patents
Method for testing gadolinia-added uranium dioxide pelletInfo
- Publication number
- JP2000147186A JP2000147186A JP10313580A JP31358098A JP2000147186A JP 2000147186 A JP2000147186 A JP 2000147186A JP 10313580 A JP10313580 A JP 10313580A JP 31358098 A JP31358098 A JP 31358098A JP 2000147186 A JP2000147186 A JP 2000147186A
- Authority
- JP
- Japan
- Prior art keywords
- pellet
- heating test
- ratio
- gadolinia
- test
- 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 128
- 238000012360 testing method Methods 0.000 title claims abstract description 122
- OOAWCECZEHPMBX-UHFFFAOYSA-N oxygen(2-);uranium(4+) Chemical compound [O-2].[O-2].[U+4] OOAWCECZEHPMBX-UHFFFAOYSA-N 0.000 title claims abstract description 35
- FCTBKIHDJGHPPO-UHFFFAOYSA-N uranium dioxide Inorganic materials O=[U]=O FCTBKIHDJGHPPO-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 238000000034 method Methods 0.000 title claims description 28
- 238000010438 heat treatment Methods 0.000 claims abstract description 113
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 34
- 239000001257 hydrogen Substances 0.000 claims abstract description 26
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 26
- 238000005259 measurement Methods 0.000 claims abstract description 15
- 239000013078 crystal Substances 0.000 claims abstract description 13
- 125000004429 atom Chemical group 0.000 claims abstract description 8
- 229910052751 metal Inorganic materials 0.000 claims abstract description 8
- 239000002184 metal Substances 0.000 claims abstract description 8
- 239000003758 nuclear fuel Substances 0.000 claims abstract description 8
- 238000010998 test method Methods 0.000 claims abstract description 8
- 125000004430 oxygen atom Chemical group O* 0.000 claims abstract description 7
- 238000001739 density measurement Methods 0.000 claims abstract description 3
- 230000000694 effects Effects 0.000 abstract description 12
- 238000011156 evaluation Methods 0.000 abstract description 3
- CMIHHWBVHJVIGI-UHFFFAOYSA-N gadolinium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[Gd+3].[Gd+3] CMIHHWBVHJVIGI-UHFFFAOYSA-N 0.000 description 11
- 229910052688 Gadolinium Inorganic materials 0.000 description 10
- 238000005245 sintering Methods 0.000 description 10
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 238000012937 correction Methods 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 229910052770 Uranium Inorganic materials 0.000 description 4
- 239000001307 helium Substances 0.000 description 4
- 229910052734 helium Inorganic materials 0.000 description 4
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 3
- 239000011261 inert gas Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000006096 absorbing agent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 229910001938 gadolinium oxide Inorganic materials 0.000 description 1
- 229940075613 gadolinium oxide Drugs 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
- 239000013585 weight reducing agent Substances 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]
【発明の属する技術分野】本発明は、原子炉燃料に使用
する核燃料ペレットの製造段階における特性評価技術に
関し、特にガドリニア添加二酸化ウランペレットの焼き
しまり安定性評価に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for evaluating characteristics of nuclear fuel pellets used in nuclear reactor fuel in a production stage, and more particularly to an evaluation of burning stability of gadolinia-added uranium dioxide pellets.
【０００２】[0002]
【従来の技術】原子炉燃料に使用する二酸化ウランペレ
ットは、原料となる二酸化ウラン粉末をプレス成形して
円筒形の成形体とし、これを炉内を０〜２体積％程度の
水蒸気を添加した、水素ガス或いは水素に窒素を混合し
た混合ガス雰囲気とした焼結炉で、１６５０℃〜１８０
０℃の温度で２時間〜６時間程度焼結した後、円筒面を
研削加工する方法で通常は製造される。また、中性子吸
収材である酸化ガドリニウム（ガドリニア）を添加した
二酸化ウランペレット（ガドリニア添加二酸化ウランペ
レット）の場合も、二酸化ウラン粉末にガドリニア粉末
を添加混合した混合粉末をプレス成形して円筒形の成形
体とし、これを炉内を２〜８体積％程度の水蒸気を添加
した、水素ガス或いは水素に窒素を混合した混合ガス雰
囲気とした焼結炉で、１６５０℃〜１８００℃の温度で
２時間〜６時間程度焼結した後、円筒面を研削加工する
という方法で通常は製造される。2. Description of the Related Art Uranium dioxide pellets used as nuclear reactor fuel are obtained by press-forming uranium dioxide powder as a raw material to form a cylindrical compact, and the inside of the reactor is added with about 0 to 2% by volume of steam. In a sintering furnace with a mixed gas atmosphere of hydrogen gas or hydrogen mixed with nitrogen.
After sintering at a temperature of 0 ° C. for about 2 to 6 hours, it is usually manufactured by a method of grinding a cylindrical surface. Also, in the case of uranium dioxide pellets (gadolinia-added uranium dioxide pellets) to which gadolinium oxide (gadolinia), which is a neutron absorber, is added, a mixed powder obtained by adding gadolinia powder to uranium dioxide powder and press-mixing is formed into a cylindrical shape. This is a sintering furnace in which the inside of the furnace is a hydrogen gas or a mixed gas atmosphere in which nitrogen is mixed with hydrogen to which about 2 to 8% by volume of steam has been added, at a temperature of 1650 ° C. to 1800 ° C. for 2 hours to After sintering for about 6 hours, it is usually manufactured by grinding the cylindrical surface.
【０００３】製造されたペレットに対しては、寸法、密
度、不純物含有率、Ｕ235 濃縮度等の特性が試験分析さ
れるが、特性の一つとして焼きしまり安定性値を評価す
ることがある。これは、ペレットを再加熱した場合の密
度上昇値を試験評価するもので、試験方法としては、予
め密度を測定したペレットを、加熱炉を用いて乾水素雰
囲気中で１７００℃〜１７５０℃の高温で２４時間加熱
試験し、冷却後ペレット密度を測定して、加熱試験後の
密度と加熱試験前の密度との差をとるという方法が用い
られることが多い。[0003] The manufactured pellets are tested and analyzed for characteristics such as size, density, impurity content, and U235 enrichment, and one of the characteristics is to evaluate the burning stability value. . This test evaluates the density increase value when the pellets are reheated. As a test method, the pellets whose density has been measured in advance are heated to 1700 ° C. to 1750 ° C. in a dry hydrogen atmosphere using a heating furnace. For 24 hours, and measuring the pellet density after cooling, and taking the difference between the density after the heating test and the density before the heating test.
【０００４】具体的には、サンプルとなるペレットとし
て、割れや欠け等の欠陥の無いものを選び、まず、加熱
試験前のペレット重量Ｗｉ（ｇ）と直径Ｄｉ（ｃｍ）と
長さＬｉ（ｃｍ）を測定して、 ４・Ｗｉ／（π・Ｄｉ2 ・Ｌｉ） ……式（１） により加熱試験前ペレット密度ｐｉ（ｇ／ｃｍ3 ）を求
めておく。次に上記条件で加熱試験を行った加熱試験後
のペレットの、直径Ｄｆ（ｃｍ）と長さＬｆ（ｃｍ）を
測定して、 ４・Ｗｉ／（π・Ｄｆ2 ・Ｌｆ） ……式（２） により加熱試験後ペレット密度ｐｆ（ｇ／ｃｍ3 ）を求
め、 ｐｆ−ｐｉ＝δｐ ……式（３） により焼きしまり安定性値δｐ（ｇ／ｃｍ3 ）を得る。Specifically, a pellet having no defect such as crack or chip is selected as a pellet to be a sample. First, a pellet weight Wi (g), a diameter Di (cm) and a length Li (cm) before a heating test are performed. ) Is measured, and the pellet density pi (g / cm 3 ) before the heating test is determined by the following formula: 4 · Wi / (π · Di 2 · Li) Formula (1) Next, the diameter Df (cm) and the length Lf (cm) of the pellet after the heating test under the above-mentioned heating test were measured, and 4 · Wi / (π · Df 2 · Lf) Equation (4) 2) After the heating test, the pellet density pf (g / cm 3 ) is obtained, and pf-pi = δp is obtained by the formula ( 3 ) to obtain a burning stability value δp (g / cm 3 ).
【０００５】通常この方法では、加熱試験によりペレッ
トの重量は変化せず、体積（寸法）が収縮するため、加
熱試験後のペレットの密度が上昇するが、ガドリニア添
加二酸化ウランペレットの場合には、特にガドリニア添
加率が高くなると、加熱試験後のペレットの重量が減少
する場合がある。この理由は、ガドリニア添加二酸化ウ
ランペレットは比較的に還元されやすい性質を有してお
り、上記加熱試験を行うことにより乾水素により還元さ
れるためであって、還元されることによって、酸素原子
数に対する金属原子数の比（Ｏ／Ｍ比）が低下すること
になる。[0005] In this method, the weight of the pellet does not change during the heating test, and the volume (dimension) shrinks, so that the density of the pellet after the heating test increases. However, in the case of gadolinia-added uranium dioxide pellet, In particular, when the gadolinia addition rate increases, the weight of the pellet after the heating test may decrease. This is because gadolinia-added uranium dioxide pellets have the property of being relatively easily reduced, and are reduced by dry hydrogen by performing the above heating test. , The ratio of the number of metal atoms to the ratio (O / M ratio) decreases.
【０００６】ところが、Ｏ／Ｍ比が低下すると、結晶格
子定数が増大して体積が膨張する効果が発現して、加熱
による体積収縮効果と競合することになる。即ち、ガド
リニア添加二酸化ウランペレットを上記加熱試験方法で
試験を行うと、乾水素による還元による影響を受ける場
合がある。このような場合に、還元による影響を排除す
るための方法として、従来、上記加熱試験をヘリウムや
アルゴン等の不活性ガス雰囲気で行うことや、ペレット
製造時と同じ水蒸気を添加した水素ガス雰囲気で行うこ
とも試みられている。しかし、ヘリウムやアルゴンとい
った不活性ガスは、水素ガスよりも高価であり、また、
乾水素ガス雰囲気で加熱試験を行うための加熱炉で、不
活性ガス雰囲気や水蒸気を添加した水素ガス雰囲気で加
熱試験を行うと、微量な空気の混入や水蒸気の解離によ
り生成する酸素のために、乾水素を使用する場合と比較
してヒータの寿命が短くなり、試験コストが増加するこ
とになる。However, when the O / M ratio decreases, the effect of expanding the volume due to the increase of the crystal lattice constant appears, and competes with the volume shrinkage effect by heating. That is, when gadolinia-added uranium dioxide pellets are tested by the above-mentioned heating test method, they may be affected by reduction by dry hydrogen. In such a case, as a method for eliminating the influence of the reduction, conventionally, the heating test is performed in an inert gas atmosphere such as helium or argon, or in a hydrogen gas atmosphere to which the same steam as in the pellet production is added. Attempts have been made to do so. However, inert gases such as helium and argon are more expensive than hydrogen gas,
In a heating furnace for performing a heating test in a dry hydrogen gas atmosphere, when a heating test is performed in an inert gas atmosphere or a hydrogen gas atmosphere to which steam is added, the amount of oxygen generated due to mixing of a small amount of air and dissociation of steam is reduced. As compared with the case of using dry hydrogen, the life of the heater is shortened, and the test cost is increased.
【０００７】[0007]
【発明が解決しようとする課題】本発明の目的は、ガド
リニア添加二酸化ウランペレットの焼きしまり安定性評
価のための加熱試験を行う場合に、還元による影響を排
除する試験方法を確立すると共に、試験コストの増加を
防止することにある。SUMMARY OF THE INVENTION It is an object of the present invention to establish a test method for eliminating the influence of reduction when performing a heating test for evaluating the burning stability of gadolinia-added uranium dioxide pellets, and to establish a test method. The purpose is to prevent an increase in cost.
【０００８】[0008]
【課題を解決するための手段】本発明は、下記の事項を
その特徴としている。 （１） 原子炉燃料に使用するガドリニア添加二酸化ウ
ランペレットの焼きしまり安定性評価のための加熱試験
において、ペレットの酸素原子数対金属原子数比（Ｏ／
Ｍ比）と結晶格子定数の関係を利用して、乾水素雰囲気
中での加熱試験前後のペレット密度測定と、加熱試験前
後のペレットのＯ／Ｍ比測定を組み合わせることによ
り、乾水素雰囲気中での加熱試験によるペレットの還元
の影響を排除したペレットの焼きしまり安定性値（δｐ
ｖ）を求めることを特徴とするガドリニア添加二酸化ウ
ランペレットの試験方法。 （２） 原子炉燃料に使用するガドリニア添加二酸化ウ
ランペレットの焼きしまり安定性評価のための加熱試験
において、ペレットの酸素原子数対金属原子数比（Ｏ／
Ｍ比）と結晶格子定数の関係並びにペレットの重量とペ
レットのＯ／Ｍ比の関係を利用して、乾水素雰囲気中で
の加熱試験前後のペレット密度測定と、加熱試験前後の
ペレット重量測定を組み合わせることにより、乾水素雰
囲気中での加熱試験によるペレットの還元の影響を近似
的に排除したペレットの焼きしまり安定性値（δｐａ）
を求めることを特徴とするガドリニア添加二酸化ウラン
ペレットの試験方法。The present invention has the following features. (1) In a heating test for evaluating the burning stability of gadolinia-doped uranium dioxide pellets used for nuclear fuel, the ratio of the number of oxygen atoms to the number of metal atoms (O /
(M ratio) and the crystal lattice constant, and by combining the pellet density measurement before and after the heating test in a dry hydrogen atmosphere and the O / M ratio measurement of the pellet before and after the heating test, in a dry hydrogen atmosphere Stability value of the pellet (δp
A test method for gadolinia-added uranium dioxide pellets, wherein v) is obtained. (2) In a heating test for evaluating the burning stability of gadolinia-doped uranium dioxide pellets used for nuclear reactor fuel, the ratio of the number of oxygen atoms to the number of metal atoms (O /
M ratio) and the crystal lattice constant, and the relationship between the pellet weight and the O / M ratio of the pellet, to measure the pellet density before and after the heating test in a dry hydrogen atmosphere and the pellet weight measurement before and after the heating test. By combining them, the burning stability value of the pellet (δpa) in which the influence of the reduction of the pellet by the heating test in a dry hydrogen atmosphere is almost eliminated
A method for testing gadolinia-added uranium dioxide pellets, characterized in that:
【０００９】以下に、本発明を詳細に説明する。本発明
の第一の方法は、通常の乾水素ガス雰囲気中での加熱試
験における、加熱試験前後でのペレット密度測定に、加
熱試験前後でのペレットの酸素原子数に対する金属原子
数の比（Ｏ／Ｍ比）測定を組み合わせて、加熱試験によ
るペレットの還元が起こらなかった場合の加熱試験後密
度を算出する方法である。加熱試験によりペレット体積
は、本来の焼きしまりによる収縮とＯ／Ｍ比低下に起因
する結晶格子定数の増大による膨張により変化する。こ
こで加熱試験前のペレット重量と体積をそれぞれＷｉ，
Ｖｉとし、加熱試験後のペレット重量と体積をそれぞれ
Ｗｆ，Ｖｆとし、本来の焼きしまりによる体積収縮率と
格子定数の増大による体積膨張率とをそれぞれＳ，Ｅと
すると、加熱試験後のペレット密度は、 Ｗｆ／Ｖｆ＝Ｗｆ／（Ｖｉ・Ｓ・Ｅ） ……式（４） となる。また、本来の焼きしまりによるペレット体積変
化のみがペレットにもたらされた（還元による重量減も
格子定数の増大による膨張もない）とすると、加熱試験
後のペレット密度は、 Ｗｆ／Ｖｆ＝Ｗｉ／（Ｖｉ・Ｓ）＝Ｅ・（Ｗｉ ／（Ｖｉ・Ｓ・Ｅ））＝Ｅ・（Ｗｉ／Ｖｆ） ……式（５） となる。Hereinafter, the present invention will be described in detail. In the first method of the present invention, in a heating test in a normal dry hydrogen gas atmosphere, the ratio of the number of metal atoms to the number of oxygen atoms in the pellet before and after the heating test (O / M ratio) is a method of calculating the density after the heating test when the reduction of the pellet by the heating test does not occur by combining the measurements. According to the heating test, the pellet volume changes due to shrinkage due to the original sintering and expansion due to an increase in the crystal lattice constant caused by a decrease in the O / M ratio. Here, the weight and the volume of the pellet before the heating test were Wi,
Vi, the pellet weight and volume after the heating test are Wf and Vf, respectively, and the volume shrinkage rate due to the original annealing and the volume expansion rate due to the increase in the lattice constant are S and E, respectively. Is as follows: Wf / Vf = Wf / (Vi · S · E) Equation (4) Further, assuming that only the change in the pellet volume due to the original baking is brought to the pellet (there is no reduction in weight due to reduction and no expansion due to an increase in the lattice constant), the pellet density after the heating test is Wf / Vf = Wi / (Vi · S) = E · (Wi / (Vi · S · E)) = E · (Wi / Vf) Equation (5)
【００１０】つまり、ペレットが還元されないで本来の
焼きしまりによるペレット体積収縮のみがもたらされた
場合の、加熱後試験ペレット密度を得るには、試験前ペ
レット重量を、加熱試験後ペレット体積で除した密度
（上記従来から行われている加熱試験後ペレット密度ｐ
ｆ（式（２）））に、格子定数の増大による体積膨張率
を乗ずれば得られることになる。In other words, in order to obtain the test pellet density after heating when the pellet is not reduced and only the pellet volume shrinkage due to the original baking is obtained, the weight of the pellet before the test is divided by the volume of the pellet after the heating test. Density (after above-mentioned conventional heating test pellet density p
It can be obtained by multiplying f (Equation (2)) by the volume expansion rate due to an increase in the lattice constant.
【００１１】一方、ガドリニア添加二酸化ウランの結晶
格子定数と、Ｏ／Ｍ比の間には次の（６）式の関係があ
ることが文献により知られている。αＹｎ＝０．５９４
７−０．０１５９３Ｙ −０．０２３７９ｎ（ｎｍ） ……式（６） ここで、Ｙはガドリニア添加二酸化ウランペレット中の
Ｕモル数とＧｄモル数の合計に対するＧｄモル数の比
（ガドリニウム添加率）であり、ｎはガドリニア添加二
酸化ウランペレット中のＵモル数とＧｄモル数の合計に
対するＯモル数の比（Ｏ／Ｍ比）であり、αＹｎはＧｄ
添加率Ｙ、Ｏ／Ｍ比ｎの場合のガドリニア添加二酸化ウ
ランの結晶格子定数を表す。On the other hand, it is known from the literature that the crystal lattice constant of gadolinia-doped uranium dioxide and the O / M ratio have the following relationship (6). αYn = 0.594
7-0.01593Y-0.02379n (nm) Formula (6) Here, Y is the ratio of the number of Gd moles to the sum of the number of U moles and the number of Gd moles in the gadolinia-added uranium dioxide pellet (gadolinium addition rate). Where n is the ratio of the number of O moles to the sum of the number of U moles and Gd moles in the gadolinia-added uranium dioxide pellet (O / M ratio), and αYn is Gd
It shows the crystal lattice constant of gadolinia-doped uranium dioxide when the addition ratio Y and the O / M ratio n are n.
【００１２】従って、加熱試験前のペレットの結晶格子
定数とＯ／Ｍ比をそれぞれαＹｎｉ，ｎｉとし、加熱試
験後のペレットの結晶格子定数とＯ／Ｍ比をそれぞれα
Ｙｎｆ，ｎｆとすると、線膨張率はαＹｎｆ／αＹｎｉ
となるが、結晶格子定数の増大によるペレット膨張はほ
ぼ等方的と考えられるため、格子定数増大による体積膨
張率Ｅは、 Ｅ＝（αＹｎｆ／αＹｎｉ）3 ……式（７） となる。Therefore, the crystal lattice constant and the O / M ratio of the pellet before the heating test are set to αYni and ni, respectively, and the crystal lattice constant and the O / M ratio of the pellet after the heating test are set to αYni and ni, respectively.
Assuming that Ynf and nf, the linear expansion coefficient is αYnf / αYni
However, since the pellet expansion due to the increase in the crystal lattice constant is considered to be almost isotropic, the volume expansion rate E due to the increase in the lattice constant is as follows: E = (αYnf / αYni) 3 (7)
【００１３】これらのことを利用すると、加熱試験前後
のガドリニア添加二酸化ウランペレットのＯ／Ｍ比を測
定して式（６），（７），（５）を用いることにより、
加熱試験を乾水素雰囲気で行っても、加熱試験によるペ
レットの還元が起こらなかった場合の試験後密度を得る
ことができ、加熱試験によるペレットの還元が起こらな
かった場合の焼きしまり安定性値δｐ（ｇ／ｃｍ3 ）を
得ることができる。尚、Ｏ／Ｍ比の測定は、通常は破壊
試験であり、Ｏ／Ｍ比測定を行ったペレットに対して加
熱試験が行えなくなるが、加熱試験前のＯ／Ｍ比は、加
熱試験を行うペレットと同一の特性を有すると見なすこ
とのできる、同一ペレットロットからサンプルした別の
ペレットに対して測定しても本目的には全く不都合を生
じない。Utilizing these facts, the O / M ratio of gadolinia-doped uranium dioxide pellets before and after the heating test is measured, and by using equations (6), (7), and (5),
Even if the heating test is performed in a dry hydrogen atmosphere, it is possible to obtain a density after the test when the reduction of the pellets by the heating test does not occur, and the baked stability value δp when the reduction of the pellets does not occur by the heating test. (G / cm 3 ). Note that the measurement of the O / M ratio is usually a destructive test, and the heating test cannot be performed on the pellets subjected to the O / M ratio measurement. Measurement for another pellet sampled from the same pellet lot, which can be considered to have the same properties as the pellet, does not cause any disadvantage for this purpose.
【００１４】上記加熱試験前後のガドリニア添加二酸化
ウランペレットのＯ／Ｍ比を測定して、加熱試験による
ペレットの還元が起こらなかった場合の試験後密度を得
る方法は、Ｏ／Ｍ比の測定誤差に起因する誤差を除け
ば、厳密に還元が起こらなかった場合の試験後密度が得
られる方法であるが、Ｏ／Ｍ比の測定を行わなければな
らないという煩雑を伴う。そこで、若干の誤差は伴うも
のの、還元が起こらなかった場合の試験後密度をより簡
便に得るために確立したのが第二の方法である。The method of measuring the O / M ratio of gadolinia-added uranium dioxide pellets before and after the above heating test and obtaining the post-test density in the case where the pellets did not undergo reduction by the heating test is based on the measurement error of the O / M ratio. This method can obtain the density after the test in the case where the reduction does not occur strictly except for the error caused by the above, but involves the trouble that the O / M ratio must be measured. Thus, the second method has been established in order to more easily obtain the post-test density in the case where no reduction has occurred, albeit with some error.
【００１５】本発明の第二の方法は、加熱試験後のペレ
ットのＯ／Ｍ比は加熱試験前のＯ／Ｍ比と加熱試験後の
ペレット重量から算出できることと、加熱試験前のペレ
ットのＯ／Ｍ比は通常ほぼ一定の値をとることを利用
し、通常の乾水素ガス雰囲気中での加熱試験における、
加熱試験前後でのペレット密度測定に、加熱試験前後で
のペレット重量測定を組み合わせて、加熱試験によるペ
レットの還元が起こらなかった場合の加熱試験後密度を
近似的に導出する方法である。According to a second method of the present invention, the O / M ratio of the pellet after the heating test can be calculated from the O / M ratio before the heating test and the weight of the pellet after the heating test. Utilizing that the / M ratio usually takes a substantially constant value, and in a heating test in a normal dry hydrogen gas atmosphere,
In this method, the density of the pellet before and after the heating test is combined with the measurement of the weight of the pellet before and after the heating test, and the density after the heating test when the reduction of the pellet by the heating test does not occur is approximately derived.
【００１６】上述の様に、Ｙをガドリニア添加二酸化ウ
ランペレット中のＵモル数とＧｄモル数の合計に対する
Ｇｄモル数の比（ガドリニウム添加率）とし、ｎｉを加
熱試験前のペレットＯ／Ｍ比、ｎｆを加熱試験後のペレ
ットＯ／Ｍ比、Ｗｉを加熱試験前のペレット重量、ＷＬ
を加熱試験によるペレット重量減とすると、ウランとガ
ドリニウムと酸素の原子量はそれぞれ２３８と１５７．
２５と１６であるから、加熱試験前のペレット中の（ウ
ラン＋ガドリニウム）のモル数はＷｉ／｛２３８・（１
−Ｙ）＋１５７．２５・Ｙ＋１６・ｎｉ｝であり、酸素
のモル数はｎｉ・Ｗｉ／｛２３８・（１−Ｙ）＋１５
７．２５・Ｙ＋１６・ｎｉ｝である。また加熱試験によ
って奪われた酸素のモル数はＷＬ／１６である。As described above, Y is the ratio of the number of moles of Gd to the sum of the number of moles of U and Gd in the gadolinia-added uranium dioxide pellet (gadolinium addition ratio), and ni is the O / M ratio of the pellet before the heating test. , Nf is the pellet O / M ratio after the heating test, Wi is the pellet weight before the heating test, WL
Is the weight of the pellet by the heating test, the atomic weights of uranium, gadolinium and oxygen are 238 and 157.
Since they are 25 and 16, the number of moles of (uranium + gadolinium) in the pellet before the heating test is Wi / ｛238 · (1
−Y) + 157.25 · Y + 16 · ni}, and the number of moles of oxygen is ni · Wi / {238 · (1-Y) +15
7.25 · Y + 16 · ni｝. The number of moles of oxygen deprived by the heating test is WL / 16.
【００１７】従って、加熱試験後のペレットＯ／Ｍ比ｎ
ｆは、 ｎｆ＝［加熱試験前酸素モル数−加熱試験によって奪われた酸 素のモル数］／［（ウラン＋ガドリニウム）のモル数］ ＝｛ｎｉ・Ｗｉ／（２３８−８０．７５・Ｙ＋１６・ｎｉ） −ＷＬ／１６｝／｛Ｗｉ／（２３８−８０．７５・Ｙ ＋１６・ｎｉ）｝ ……式（８） となり、加熱試験後のペレットＯ／Ｍ比ｎｆは、加熱試
験前のペレットＯ／Ｍ比ｎｉと加熱試験前のペレット重
量Ｗｉと加熱試験によるペレット重量減ＷＬに依存して
いる。ところが、加熱試験前のペレットＯ／Ｍ比ｎｉ
は、通常１．９７〜２．０３であるため、ｎｉを固定値
２．００としてもｎｆにはわずかの影響しか与えない。Therefore, the pellet O / M ratio n after the heating test is n
f is nf = [mol number of oxygen before heating test−mol number of oxygen deprived by heating test] / [mol number of (uranium + gadolinium)] = {ni · Wi / (238−80.75 · Y + 16) · Ni) −WL / 16｝ / {Wi / (238−80.75 · Y + 16 · ni)} Equation (8), and the pellet O / M ratio nf after the heating test is the pellet before the heating test. It depends on the O / M ratio ni, the pellet weight Wi before the heating test, and the pellet weight reduction WL due to the heating test. However, the pellet O / M ratio before the heating test ni
Is usually 1.97 to 2.03, so even if ni is a fixed value of 2.00, ni has only a slight effect on nf.
【００１８】実際、ガドリニウム添加率Ｙを通常の場合
の最大値である０．１５とし、ｎｉが１．９７の場合と
２．００の場合とで加熱試験前後のＯ／Ｍ比の差の比を
とると、（１．９７−ｎｆ）／（２．００−ｎｆ）＝
０．９９８１となり、ｎｉを固定値２．００としてもｎ
ｆにはわずかの影響しか与えないことがわかる。Actually, the gadolinium addition rate Y is set to 0.15, which is the maximum value in a normal case, and the ratio of the difference between the O / M ratio before and after the heating test when ni is 1.97 and 2.00. Then, (1.97-nf) / (2.00-nf) =
0.9981, and even if ni is a fixed value of 2.00, n
It can be seen that f has only a slight effect.
【００１９】そこで、式（６），式（７），式（５），
式（２）から、加熱試験によるペレットの還元が起こら
なかった場合の近似的な試験後密度ｐｆａは、 ｐｆａ＝《［０．５９４７−０．０１５９３・Ｙ −０．０２３７９・｛２−ＷＬ・（２７０ −８０．７５・Ｙ）／（１６・Ｗｉ）｝］ ／（０．５４７１−０．０１５９３・Ｙ）》3 ・｛４・Ｗｉ／（π・Ｄｆ2 ・Ｌｆ）｝ ……式（９） で与えられ、加熱試験前後のペレット重量と加熱試験後
のペレット直径及び長さを測定することにより、加熱試
験を乾水素雰囲気で行っても、加熱試験によるペレット
の還元が起こらなかった場合の試験後密度の近似値を得
ることができ、加熱試験によるペレットの還元が起こら
なかった場合の焼きしまり安定性値δｐを近似的に得る
ことができる。Therefore, equations (6), (7), (5),
From the equation (2), an approximate post-test density pfa when the reduction of the pellets by the heating test did not occur is as follows: pfa = << [0.5947−0.01593 · Y−0.02379 · ｛2-WL · (270−80.75 · Y) / (16 · Wi)}] / (0.5471−0.01593 · Y) » 3 · {4 · Wi / (π · Df 2 · Lf)}… Formula ( 9) When the weight of the pellet before and after the heating test and the diameter and length of the pellet after the heating test are measured, and the heating test is performed in a dry hydrogen atmosphere, the pellet is not reduced by the heating test. , An approximate value of the density after the test can be obtained, and the burning stability value δp when the reduction of the pellet by the heating test does not occur can be approximately obtained.
【００２０】[0020]
【発明の実施の形態】本発明における具体例として、ガ
ドリニア添加率が４．５重量％（ガドリニウム添加率Ｙ
＝０．０６５６）と７．５重量％（ガドリニウム添加率
Ｙ＝０．１０７８）のガドリニア添加二酸化ウランペレ
ットの、乾水素雰囲気中での加熱試験による、通常の方
法によって得た焼きしまり安定性値δｐｒと、加熱試験
前後のＯ／Ｍ比測定を組み合わせて行って得た（第一の
方法）加熱試験による還元の影響を排除した焼きしまり
安定性値δｐｖと、加熱試験前後の重量測定を組み合わ
せて行って得た（第二の方法）加熱試験による還元の影
響を近似的に排除した焼きしまり安定性値δｐａを、表
１に示す。DESCRIPTION OF THE PREFERRED EMBODIMENTS As a specific example of the present invention, a gadolinium addition rate is 4.5% by weight (a gadolinium addition rate Y).
= 0.0656) and 7.5% by weight (addition ratio of gadolinium Y = 0.1078) of gadolinia-doped uranium dioxide pellets, obtained by a heating test in a dry hydrogen atmosphere, obtained by a normal method. δpr combined with the O / M ratio measurement before and after the heating test (first method) Combination of the sintering stability value δpv excluding the effect of reduction by the heating test and the weight measurement before and after the heating test Table 2 shows the baking stability value δpa obtained by performing the heating test (second method) and substantially eliminating the influence of reduction by the heating test.
【００２１】当該ガドリニア添加二酸化ウランペレット
と同一の製造ロットから各１０ペレットずつサンプルし
たペレットを、当該ガドリニア添加二酸化ウランペレッ
トを製造する際の焼結に使用した水蒸気添加水素雰囲気
と同じ雰囲気による加熱試験によって得た、焼きしまり
安定性値の平均値は、ガドリニア添加率４．５重量％の
ガドリニア添加二酸化ウランペレットの場合に０．０２
９７（ｇ／ｃｍ3 ）であり、ガドリニア添加率７．５重
量％のガドリニア添加二酸化ウランペレットの場合に
０．０１８８（ｇ／ｃｍ3 ）であった。Heating test of 10 pellets each sampled from the same production lot as the gadolinia-added uranium dioxide pellets in the same atmosphere as the steam-added hydrogen atmosphere used for sintering when producing the gadolinia-added uranium dioxide pellets. The average value of the baked-in stability values obtained in Example 1 was 0.02 in the case of gadolinia-added uranium dioxide pellets having a gadolinia addition ratio of 4.5% by weight.
97 (g / cm 3 ), and 0.0188 (g / cm 3 ) in the case of gadolinia-added uranium dioxide pellets having a gadolinia addition ratio of 7.5% by weight.
【００２２】これらの結果から、本発明の第一の方法に
よって乾水素雰囲気で加熱試験を行えば、水蒸気添加水
素雰囲気で加熱試験を行った場合と同等の焼きしまり安
定性値が得られる。また、本発明の第二の方法によって
も、高々５％程度の誤差で水蒸気添加水素雰囲気で加熱
試験を行った場合と同等の焼きしまり安定性値が得られ
ることが分る。From these results, when the heating test is performed in a dry hydrogen atmosphere according to the first method of the present invention, the same baking stability value as in the case where the heating test is performed in a hydrogen added hydrogen atmosphere can be obtained. In addition, it can be seen that the second method of the present invention can provide the same sintering stability value as that obtained when the heating test is performed in a hydrogen-added hydrogen atmosphere with an error of at most about 5%.
【００２３】[0023]
【表１】 [Table 1]
【００２４】[0024]
【発明の効果】本発明の第一の方法により、ペレットの
加熱試験前後でのＯ／Ｍ比測定を行うという若干の試験
工数増加のみで、単価が低廉でかつ加熱炉のヒータへの
悪影響の少ない乾水素雰囲気での加熱試験により、ガド
リニア添加二酸化ウランペレットの、還元による影響を
排除した焼きしまり安定性評価を行うことが可能とな
り、還元による影響を排除するために、加熱試験雰囲気
としてヘリウムやアルゴンといった不活性雰囲気や水蒸
気を添加した水素雰囲気を使用する場合に比較して、低
コストで試験が行える様になった。According to the first method of the present invention, the unit cost is low and the adverse effect on the heater of the heating furnace is reduced by only slightly increasing the number of test steps of measuring the O / M ratio before and after the heating test of the pellet. The heating test in a small amount of dry hydrogen atmosphere makes it possible to evaluate the burning stability of gadolinia-doped uranium dioxide pellets without the effects of reduction.In order to eliminate the effects of reduction, helium or helium was used as the heating test atmosphere. The test can be performed at lower cost than when using an inert atmosphere such as argon or a hydrogen atmosphere to which water vapor is added.
【００２５】また、本発明の第二の方法により、若干の
誤差を許容すれば、従来方法に比較して加熱試験後のペ
レット重量の測定工数の増加のみで、単価が低廉でかつ
加熱炉のヒータへの悪影響の少ない乾水素雰囲気での加
熱試験により、ガドリニア添加二酸化ウランペレット
の、還元による影響を近似的に排除した焼きしまり安定
性評価を低コストで行うことが可能となった。Further, according to the second method of the present invention, if a slight error is allowed, only the increase in the number of steps for measuring the weight of the pellets after the heating test as compared with the conventional method, the unit price is low and the heating furnace A heating test in a dry hydrogen atmosphere that has little adverse effect on the heater has made it possible to evaluate the sintering stability of gadolinia-doped uranium dioxide pellets at a low cost without approximately eliminating the effects of reduction.
─────────────────────────────────────────────────────
────────────────────────────────────────────────── ───
【手続補正書】[Procedure amendment]
【提出日】平成１１年９月１６日（１９９９．９．１
６）[Submission Date] September 16, 1999 (1999.9.1)
6)
【手続補正１】[Procedure amendment 1]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】特許請求の範囲[Correction target item name] Claims
【補正方法】変更[Correction method] Change
【補正内容】[Correction contents]
【特許請求の範囲】[Claims]
【手続補正２】[Procedure amendment 2]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】０００９[Correction target item name] 0009
【補正方法】変更[Correction method] Change
【補正内容】[Correction contents]
【０００９】以下に、本発明を詳細に説明する。本発明
の第一の方法は、通常の乾水素ガス雰囲気中での加熱試
験における、加熱試験前後でのペレット密度測定に、加
熱試験前後でのペレットの酸素原子数に対する金属原子
数の比（Ｏ／Ｍ比）測定を組み合わせて、加熱試験によ
るペレットの還元が起こらなかった場合の加熱試験後密
度を算出する方法である。加熱試験によりペレット体積
は、本来の焼きしまりによる収縮とＯ／Ｍ比低下に起因
する結晶格子定数の増大による膨張により変化する。こ
こで加熱試験前のペレット重量と体積をそれぞれＷｉ，
Ｖｉとし、加熱試験後のペレット重量と体積をそれぞれ
Ｗｆ，Ｖｆとし、本来の焼きしまりによる体積収縮率と
格子定数の増大による体積膨張率とをそれぞれＳ，Ｅと
すると、加熱試験後のペレット密度は、 Ｗｆ／Ｖｆ＝Ｗｆ／（Ｖｉ・Ｓ・Ｅ） ……式（４） となる。また、本来の焼きしまりによるペレット体積変
化のみがペレットにもたらされた（還元による重量減も
格子定数の増大による膨張もない）とすると、加熱試験
後のペレット密度は、 ｐｆｅ＝Ｗｉ／（Ｖｉ・Ｓ）＝Ｅ・（Ｗｉ ／（Ｖｉ・Ｓ・Ｅ））＝Ｅ・（Ｗｉ／Ｖｆ） ……式（５） となる。Hereinafter, the present invention will be described in detail. In the first method of the present invention, in a heating test in a normal dry hydrogen gas atmosphere, the ratio of the number of metal atoms to the number of oxygen atoms in the pellet before and after the heating test (O / M ratio) is a method of calculating the density after the heating test when the reduction of the pellet by the heating test does not occur by combining the measurements. According to the heating test, the pellet volume changes due to shrinkage due to the original sintering and expansion due to an increase in the crystal lattice constant caused by a decrease in the O / M ratio. Here, the weight and the volume of the pellet before the heating test were Wi,
Vi, the pellet weight and volume after the heating test are Wf and Vf, respectively, and the volume shrinkage rate due to the original annealing and the volume expansion rate due to the increase in the lattice constant are S and E, respectively. Is as follows: Wf / Vf = Wf / (Vi · S · E) Equation (4) Further, assuming that only the change in the pellet volume due to the original baking is brought to the pellet (there is no weight loss due to reduction and no expansion due to an increase in the lattice constant), the pellet density after the heating test is as follows: pfe = Wi / (Vi S) = E · (Wi / (Vi · S · E)) = E · (Wi / Vf) (5)
Claims (2)
化ウランペレットの焼きしまり安定性評価のための加熱
試験において、ペレットの酸素原子数対金属原子数比
（Ｏ／Ｍ比）と結晶格子定数の関係を利用して、乾水素
雰囲気中での加熱試験前後のペレット密度測定と、加熱
試験前後のペレットのＯ／Ｍ比測定を組み合わせること
により、乾水素雰囲気中での加熱試験によるペレットの
還元の影響を排除したペレットの焼きしまり安定性値を
求めることを特徴とするガドリニア添加二酸化ウランペ
レットの試験方法。In a heating test for evaluating the burning stability of gadolinia-added uranium dioxide pellets used as a reactor fuel, the ratio of the number of oxygen atoms to the number of metal atoms (O / M ratio) and the crystal lattice constant of the pellets is determined. Utilizing the relationship, by combining the pellet density measurement before and after the heating test in a dry hydrogen atmosphere and the O / M ratio measurement of the pellet before and after the heating test, the reduction of the pellet by the heating test in the dry hydrogen atmosphere is reduced. A test method for gadolinia-added uranium dioxide pellets, which comprises determining a burning stability value of a pellet excluding the influence.
化ウランペレットの焼きしまり安定性評価のための加熱
試験において、ペレットの酸素原子数対金属原子数比
（Ｏ／Ｍ比）と結晶格子定数の関係並びにペレットの重
量とペレットのＯ／Ｍ比の関係を利用して、乾水素雰囲
気中での加熱試験前後のペレット密度測定と、加熱試験
前後のペレット重量測定を組み合わせることにより、乾
水素雰囲気中での加熱試験によるペレットの還元の影響
を近似的に排除したペレットの焼きしまり安定性値を求
めることを特徴とするガドリニア添加二酸化ウランペレ
ットの試験方法。2. In a heating test for evaluating the burning stability of gadolinia-added uranium dioxide pellets used for nuclear reactor fuel, the ratio of the number of oxygen atoms to the number of metal atoms (O / M ratio) and the crystal lattice constant of the pellets is determined. By utilizing the relationship and the relationship between the pellet weight and the O / M ratio of the pellet, the measurement of the pellet density before and after the heating test in a dry hydrogen atmosphere and the measurement of the pellet weight before and after the heating test are combined. A method for testing gadolinia-added uranium dioxide pellets, comprising determining a burning stability value of pellets in which the influence of reduction of pellets by a heating test is approximately eliminated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10313580A JP3040756B1 (en) | 1998-11-04 | 1998-11-04 | Test method for gadolinia-doped uranium dioxide pellets |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10313580A JP3040756B1 (en) | 1998-11-04 | 1998-11-04 | Test method for gadolinia-doped uranium dioxide pellets |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP3040756B1 JP3040756B1 (en) | 2000-05-15 |
| JP2000147186A true JP2000147186A (en) | 2000-05-26 |
Family
ID=18043030
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10313580A Expired - Fee Related JP3040756B1 (en) | 1998-11-04 | 1998-11-04 | Test method for gadolinia-doped uranium dioxide pellets |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3040756B1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006005905A2 (en) * | 2004-07-08 | 2006-01-19 | British Nuclear Fuels Plc | Method for the handling and minimisation of waste |
| US7094608B2 (en) * | 2002-04-11 | 2006-08-22 | Korea Atomic Energy Research Institute | Method for measuring lanthanide content dissolved in uranium oxide |
-
1998
- 1998-11-04 JP JP10313580A patent/JP3040756B1/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7094608B2 (en) * | 2002-04-11 | 2006-08-22 | Korea Atomic Energy Research Institute | Method for measuring lanthanide content dissolved in uranium oxide |
| WO2006005905A2 (en) * | 2004-07-08 | 2006-01-19 | British Nuclear Fuels Plc | Method for the handling and minimisation of waste |
| WO2006005905A3 (en) * | 2004-07-08 | 2006-04-27 | British Nuclear Fuels Plc | Method for the handling and minimisation of waste |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3040756B1 (en) | 2000-05-15 |
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