JPS6322550B2 - - Google Patents
Info
- Publication number
- JPS6322550B2 JPS6322550B2 JP57007323A JP732382A JPS6322550B2 JP S6322550 B2 JPS6322550 B2 JP S6322550B2 JP 57007323 A JP57007323 A JP 57007323A JP 732382 A JP732382 A JP 732382A JP S6322550 B2 JPS6322550 B2 JP S6322550B2
- Authority
- JP
- Japan
- Prior art keywords
- nuclear fuel
- nuclear
- well
- fuel
- pellet
- 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
- 239000003758 nuclear fuel Substances 0.000 claims description 73
- 239000008188 pellet Substances 0.000 claims description 59
- 239000000463 material Substances 0.000 claims description 53
- 239000000446 fuel Substances 0.000 claims description 27
- 238000005253 cladding Methods 0.000 claims description 18
- 239000002131 composite material Substances 0.000 claims description 14
- 230000004992 fission Effects 0.000 claims description 10
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 17
- 229910052770 Uranium Inorganic materials 0.000 description 13
- 238000010586 diagram Methods 0.000 description 8
- OYEHPCDNVJXUIW-FTXFMUIASA-N 239Pu Chemical compound [239Pu] OYEHPCDNVJXUIW-FTXFMUIASA-N 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- JFALSRSLKYAFGM-OIOBTWANSA-N uranium-235 Chemical compound [235U] JFALSRSLKYAFGM-OIOBTWANSA-N 0.000 description 6
- XLYOFNOQVPJJNP-ZSJDYOACSA-N Heavy water Chemical compound [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 4
- 238000010248 power generation Methods 0.000 description 4
- JFALSRSLKYAFGM-FTXFMUIASA-N uranium-233 Chemical compound [233U] JFALSRSLKYAFGM-FTXFMUIASA-N 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 description 3
- 229910052776 Thorium Inorganic materials 0.000 description 3
- 230000004907 flux Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 2
- 229910052792 caesium Inorganic materials 0.000 description 2
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 239000002826 coolant Substances 0.000 description 2
- 229910052740 iodine Inorganic materials 0.000 description 2
- 239000011630 iodine Substances 0.000 description 2
- FRWYFWZENXDZMU-UHFFFAOYSA-N 2-iodoquinoline Chemical compound C1=CC=CC2=NC(I)=CC=C21 FRWYFWZENXDZMU-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052778 Plutonium Inorganic materials 0.000 description 1
- OYEHPCDNVJXUIW-AHCXROLUSA-N Plutonium-240 Chemical compound [240Pu] OYEHPCDNVJXUIW-AHCXROLUSA-N 0.000 description 1
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 229910001093 Zr alloy Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- LTPBRCUWZOMYOC-UHFFFAOYSA-N beryllium oxide Inorganic materials O=[Be] LTPBRCUWZOMYOC-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000011824 nuclear material Substances 0.000 description 1
- 239000012038 nucleophile Substances 0.000 description 1
- 230000000269 nucleophilic effect Effects 0.000 description 1
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- ZSLUVFAKFWKJRC-UHFFFAOYSA-N thorium Chemical compound [Th] ZSLUVFAKFWKJRC-UHFFFAOYSA-N 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 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)
- Catalysts (AREA)
Description
【発明の詳細な説明】
本発明は、上端面中央に井戸型空孔部を有する
有底円筒状の核燃料物質と、前記井戸型空孔部に
嵌合する核親物質とからなる複合構造の円柱状核
燃料ペレツトを用いた核燃料棒に関し、この核燃
料棒は、発電用熱中性子原子炉において、核親物
質を効率よく核燃料物質に転換することができ、
核燃料資源の有効利用に資するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention provides a composite structure consisting of a bottomed cylindrical nuclear fuel material having a well-shaped hole in the center of its upper end surface, and a nuclear parent material that fits into the well-shaped hole. Regarding a nuclear fuel rod using cylindrical nuclear fuel pellets, this nuclear fuel rod can efficiently convert nuclear parent material into nuclear fuel material in a thermal neutron reactor for power generation,
This contributes to the effective use of nuclear fuel resources.
本明細書において、「核燃料物質」とは、原子
炉内において核***連鎖反応が持続されるのに充
分な量の核***性物質（ウラン−235、プルトニ
ウム−239、ウラン−233等）を含む安定な酸化物
状態にある物質をいい、具体的には安定な酸化物
の状態にされた濃縮ウラン（ウラン−235の含有
量を高めたもの）、プルトニウム−239を富化した
ウランがあり、原子炉が黒鉛減速炉又は重水炉の
場合は安定な酸化物状態にある天然ウランも該当
する。 As used herein, "nuclear fuel material" refers to a stable material containing fissile material (such as uranium-235, plutonium-239, uranium-233) in an amount sufficient to sustain a nuclear fission chain reaction in a nuclear reactor. Refers to substances in an oxide state, specifically enriched uranium (with increased content of uranium-235) that has been made into a stable oxide state, and uranium enriched with plutonium-239. In the case of a graphite-moderated reactor or a heavy water reactor, natural uranium in a stable oxide state also falls under this category.
また、一般的に核親物質とは、中性子を吸収す
ると核***性物質に転換する物質そのものをいう
が、本明細書において「核親物質」とは、核***
性物質は含んでいないか、含んでいても核***連
鎖反応を持続させる量以下であつて、しかも中性
子を吸収して核***性物質に転換する物質（ウラ
ン−238、プルトニウム−240、トリウム−232等）
を多く含む安定な酸化物状態にある物質をいい、
具体的には安定な酸化物の状態にされた劣化ウラ
ン、トリウムがあり、原子炉が軽水炉の場合は安
定な酸化物状態にある天然ウランも該当する。 In addition, a nuclear parent material generally refers to a substance itself that converts into fissile material when it absorbs neutrons, but in this specification, a "nuclear parent material" does not include or does not contain a fissile material. Substances that absorb neutrons and convert into fissile materials (such as uranium-238, plutonium-240, thorium-232, etc.), but the amount is less than that which sustains a nuclear fission chain reaction.
A substance in a stable oxide state containing a large amount of
Specifically, there are depleted uranium and thorium that are in a stable oxide state, and if the reactor is a light water reactor, natural uranium that is in a stable oxide state also falls under this category.
核燃料資源の有効利用を図るためには、地表上
に存在して、その大部分を占めるウラン−238お
よびトリウムを、核***性のウラン−235等の燃
焼（核***反応）時に生じる中性子を吸収させて
核***性のプルトニウム−239やウラン−233に転
換させ、得られた核***性物質を再び核***させ
てエネルギーを取出すことが重要であり、この転
換効率の目安としては、転換比という術語が用い
られる。これは、原子炉の核燃料棒の中で核***
性物質の原子核が１個核***して消費される毎に
２〜３個の中性子を発生するが、この中性子の一
部を吸収して非***性物質の原子核が新しく核分
裂性物質の原子核に転換する相対数のことであ
る。この転換比が核燃料資源の有効利用の観点か
らは熱中性子原子炉で可能な限り、1.0に近い値
になることが必要であり、勿論、増殖炉では、こ
の転換比は１以上である。 In order to effectively utilize nuclear fuel resources, uranium-238 and thorium, which exist on the earth's surface and make up the majority of it, must be absorbed by the neutrons generated during the combustion of fissile uranium-235 (fission reaction). It is important to convert nuclear materials into fissile plutonium-239 and uranium-233, and then fission the resulting fissile material again to extract energy, and the term conversion ratio is used as a measure of this conversion efficiency. This is because 2 to 3 neutrons are generated each time one nucleus of fissile material is fissioned and consumed in the nuclear fuel rod of a nuclear reactor. It is the relative number of nuclei of a substance that convert into new nuclei of fissile material. From the viewpoint of effective utilization of nuclear fuel resources, it is necessary for this conversion ratio to be as close to 1.0 as possible in a thermal neutron reactor, and of course, in a breeder reactor, this conversion ratio is 1 or more.
従来の増殖炉の概念は、高速増殖炉も含めて第
１図に示すように、ウラン−235やプルトニウム
−239などの核***性物質の濃度が高く核***連
鎖反応を持続的に維持するアクテイブ炉心５と、
その周囲にウラン−238やトリウムを含む核親物
質を配置したブランケツト炉心６とによつて原子
炉炉心４が構成され、その炉心４を冷却材３が循
環し、高温冷却材が炉心部から出て、蒸気発生、
タービン駆動さらに発電に寄与する。なお、符号
１は原子炉容器、符号２は中性子反射体をそれぞ
れ示す。そして、炉心４で使用される核燃料棒
は、第２図に示すように、下端部に下部端栓７を
周溶接した燃料被覆管８の中に、多数の円柱状ペ
レツトを積層装填し、上端部を上部端栓１３で周
溶接したものが一般的である。アクテイブ炉心５
で用いられる核燃料棒は、同図に示されているよ
うに、積層ペレツトの中央部には核燃料物質のペ
レツト９が用いられ、その上下のブランケツト炉
心厚さに相当する部分に核親物質のペレツト１２
が用いられる。なお、符号１０は断熱ペレツト、
符号１１はプレナムのコイル・スプリングであ
る。また、第１図のブランケツト炉心６の側部に
用いる核燃料棒は、基本的には第２図の如きもの
であるが、装填される核燃料ペレツトが全て核親
物質であつて、そのペレツト外径寸法がアクテイ
ブ炉心５のものより大きいことが異なつている。 The concept of a conventional breeder reactor, including a fast breeder reactor, is an active core that maintains a continuous nuclear fission chain reaction with a high concentration of fissile materials such as uranium-235 and plutonium-239, as shown in Figure 1. and,
A nuclear reactor core 4 is constituted by a blanket core 6 around which a nuclear parent material containing uranium-238 and thorium is placed.A coolant 3 circulates through the core 4, and high-temperature coolant comes out of the core. to generate steam,
Turbine drive further contributes to power generation. In addition, the code|symbol 1 shows a nuclear reactor vessel, and the code|symbol 2 shows a neutron reflector, respectively. As shown in FIG. 2, the nuclear fuel rods used in the reactor core 4 are constructed by stacking a large number of cylindrical pellets in a fuel cladding tube 8 to which a lower end plug 7 is circumferentially welded to the lower end. Generally, the upper end plug 13 is welded around the circumference of the upper end plug 13. active core 5
As shown in the figure, nuclear fuel rods used in the nuclear fuel rods have pellets 9 of nuclear fuel material in the center of the piled pellets, and pellets of parent material in the upper and lower parts corresponding to the thickness of the blanket core. 12
is used. In addition, the code 10 is a heat insulating pellet,
Reference numeral 11 is a plenum coil spring. Furthermore, the nuclear fuel rods used on the sides of the blanket core 6 in FIG. The difference is that the dimensions are larger than those of the active core 5.
ところで、転換比を大きくし核燃料資源を有効
利用するのに、現在、開発途上にあり、しかも、
技術的に困難な高速増殖炉を用いないで、すでに
商業化されている発電用熱中性子原子炉で実現し
ようとすると、従来技術として示した核燃料棒
（第２図）に用いられている円柱状ペレツトでは
不充分である。 By the way, in order to increase the conversion ratio and make effective use of nuclear fuel resources, there is currently a development process in progress.
If we try to realize this using a thermal neutron reactor for power generation, which has already been commercialized, without using a technically difficult fast breeder reactor, we will be able to use the cylindrical shape used in nuclear fuel rods (Fig. 2) shown as conventional technology. Pellet is not enough.
本発明は、前記のような従来技術の実情に鑑み
なされたものであつて、その目的は、高い転換比
を熱中性子原子炉で達成して、それによつて核燃
料資源の有効利用を図ることができるような核燃
料棒を提供することにある。 The present invention was made in view of the actual state of the prior art as described above, and its purpose is to achieve a high conversion ratio in a thermal neutron reactor, thereby making it possible to effectively utilize nuclear fuel resources. The goal is to provide nuclear fuel rods that can
そこで本発明では、上端面中央に井戸型空孔部
を有する有底円筒状の核燃料物質の前記井戸型空
孔部内に、核親物質を嵌合させた非均質的な複合
ペレツトを用いるよう構成されている。また、こ
のような複合ペレツトは、核***生成物（以下、
FPと略記する）のゲツター材料を嵌合させた複
合ペレツトと組合せることにより、高い燃焼度を
達成することもできる。 Therefore, in the present invention, a non-homogeneous composite pellet in which a nuclear parent material is fitted into the well-shaped hole of a bottomed cylindrical nuclear fuel material having a well-shaped hole in the center of the upper end surface is used. has been done. In addition, such composite pellets contain fission products (hereinafter referred to as
A high burnup can also be achieved by combining it with a composite pellet fitted with getter material (abbreviated as FP).
以下、図面に基づき、本発明について更に詳し
く説明する。前記のように、本発明に係る核燃料
棒で用いる円柱状核燃料ペレツトは、上端面中央
に井戸型空孔部を有する有底円筒状の核燃料物質
と、前記井戸型空孔部に嵌合する核親物質とから
なる複合構造をなすものである。 Hereinafter, the present invention will be explained in more detail based on the drawings. As described above, the cylindrical nuclear fuel pellet used in the nuclear fuel rod according to the present invention includes a bottomed cylindrical nuclear fuel material having a well-shaped hole in the center of its upper end surface, and a nucleus that fits into the well-shaped hole. It forms a composite structure consisting of a parent substance.
実施例としては、第３図に示すように、中央部
の核親物質２１を小径円柱状とし、周囲の核燃料
物質２２を上端面から中央に向つて形成された井
戸型空孔部２３を有する有底円筒状として、前記
核親物質２１が井戸型空孔部２３に嵌合状態で組
合せた構造としたものがある。なお、符号２４
は、ペレツトと燃料被覆管との力学的相互作用
（PCMI）を低減するため、ペレツト上、下端面
に形成したチヤンフア（面取り）である。 As an example, as shown in FIG. 3, the nuclear parent material 21 in the center has a small-diameter cylindrical shape, and the surrounding nuclear fuel material 22 has a well-shaped cavity 23 formed from the upper end surface toward the center. Some have a bottomed cylindrical shape and have a structure in which the nucleating material 21 is fitted into the well-shaped cavity 23. In addition, the code 24
is a chamfer formed on the upper and lower end surfaces of the pellets to reduce mechanical interaction (PCMI) between the pellets and the fuel cladding.
井戸型空孔部２３を有するペレツトにおいて、
該井戸型空孔部の形状は、第３図に示すような直
円柱状に限られるものでなく、例えば第４図に示
すように回転半楕円状としてもよいし、第５図に
示すように回転逆梯形状としてもよい。井戸型空
孔部の深さについては、ペレツト高さの約1/4〜
３／４の範囲内とするのがよい。浅すぎると該井戸
型空孔部に入れる物質の量が少なくなるし、逆に
深くなりすぎると井戸型空孔部の底面に大きなク
ラツクが入りやすくなるとともに、転換比が小さ
くなるからである。このように上方に井戸型空孔
部を有する構造のペレツトの場合には、第６図に
示すように、該ペレツト下部直径が上部直径より
もやや小さな形状とするとよい。そのような形状
とすると、ペレツト高さ方向での核***発熱量を
ほぼ一様にできるからである。また、ペレツトを
この形状としたことによる付随的メリツトとして
は、PCMIを、特にペレツト下端面において一層
低減できることの他、この種の燃料ペレツトを燃
料被覆管内に装填するにあたつて、多数個のペレ
ツトが直線状に配列されるが、この時、もしも逆
方向に配置されたペレツトが含まれていると、外
見上から容易に識別可能なことである。 In the pellet having well-shaped pores 23,
The shape of the well-shaped cavity is not limited to the right cylindrical shape as shown in FIG. 3, but may be, for example, a semi-ellipse of revolution as shown in FIG. It may also have a rotating inverted ladder shape. The depth of the well-shaped cavity is approximately 1/4 to 1/4 of the pellet height.
It is preferable to set it within the range of 3/4. If it is too shallow, the amount of material that can be put into the well-shaped cavity will be small, and if it is too deep, large cracks will easily form at the bottom of the well-shaped cavity and the conversion ratio will become small. In the case of a pellet having such a structure having a well-shaped cavity above, it is preferable that the diameter of the lower part of the pellet is slightly smaller than the diameter of the upper part, as shown in FIG. This is because with such a shape, the amount of nuclear fission heat generated in the pellet height direction can be made almost uniform. In addition, an additional benefit of using this pellet shape is that PCMI can be further reduced, especially at the bottom end surface of the pellet, and when loading this type of fuel pellet into a fuel cladding tube, it is possible to reduce PCMI even further. Although the pellets are arranged in a straight line, if there are any pellets arranged in the opposite direction, it will be easily discernible from the outside.
他の実施例としては、第７図に示すように、中
央部の核親物質２１として天然ウラン、劣化ウラ
ン、またはトリウムの安定な酸化物を小径円柱状
とし、周囲の核燃料物質２２（濃縮ウラン、プル
トニウム−239、またはウラン−233の安定な酸化
物）を上端面から中央に向つて形成された井戸型
空孔部２３を有する有底円筒状として、前記核親
物質２１を井戸型空孔部２３に嵌合状態で組合
せ、更にFPを吸収し易いゲツター材ペレツト２
５をも前記井戸型空孔部２３に嵌合させて核親物
質２１を覆うように組合せる構造のものもある。
ゲツター材料は、FPのうちでも特に腐蝕性の強
い沃素やセシウム等を吸着・吸収し易く中性子吸
収の少ない材料が好ましく、具体的にはチタン、
チタン合金、ジルコニウム、ジルコニウム合金、
ベリリウム酸化物、炭素等がある。 As another example, as shown in FIG. , plutonium-239, or uranium-233 (stable oxide of plutonium-239, or uranium-233) is shaped like a cylinder with a bottom and has a well-shaped cavity 23 formed from the upper end surface toward the center. Getter material pellets 2 that are assembled in a fitted state with part 23 and can further easily absorb FP.
5 is also fitted into the well-shaped cavity 23 to cover the nucleophilic material 21.
The getter material is preferably a material that easily adsorbs and absorbs iodine and cesium, which are particularly corrosive among FPs, and has low neutron absorption.Specifically, titanium,
titanium alloy, zirconium, zirconium alloy,
Examples include beryllium oxide and carbon.
さて、いずれにせよ本発明は、第８図に示すよ
うに、前記のような円柱状の核燃料ペレツト３０
の多数個を燃料被覆管８内に積層装填し、該燃料
被覆管８の両端を上部端栓１３及び下部端栓７で
密封した構造である。その他の構成は第２図に示
す従来のものと同じであるから、対応する部分に
同一符号を付し、それらについての記載は省略す
る。 In any case, the present invention, as shown in FIG.
The fuel cladding tube 8 has a structure in which a large number of fuel cladding tubes are stacked and loaded in a fuel cladding tube 8, and both ends of the fuel cladding tube 8 are sealed with an upper end plug 13 and a lower end plug 7. Since the other configurations are the same as the conventional one shown in FIG. 2, corresponding parts are given the same reference numerals and their description will be omitted.
すでに商業化されている発電用原子炉の種類と
しては、沸騰軽水冷却炉（BWR）及び加圧軽水
冷却炉（PWR）の軽水炉（LWR）を主流とし
て、その他に重水減速炉（HWR）、改良ガス冷
却炉（AGR）等がある。これらの燃料ペレツト
には、天然ウラン（約0.7％のウラン−235を含
有）あるいは約４％までの濃縮ウランが用いられ
ている。わが国が開発している新型転換炉
（ATR）では、天然ウランにプルトニウムを約
1.5％混合した酸化物燃料（UO2＋PuO2）が採用
されている。 The main types of power reactors that have already been commercialized are light water reactors (LWRs), boiling light water cooled reactors (BWRs) and pressurized light water cooled reactors (PWRs), as well as heavy water moderated reactors (HWRs) and improved reactors. There are gas cooled reactors (AGR), etc. These fuel pellets use either natural uranium (containing about 0.7% uranium-235) or enriched uranium up to about 4%. The new type of converter reactor (ATR) being developed by Japan combines plutonium with natural uranium.
A 1.5% mixed oxide fuel (UO 2 +PuO 2 ) is used.
いずれにしても、前記各原子炉に採用されてい
る燃料ペレツトそのものは、ペレツト全体が均一
濃度の核燃料物質で製造されており、これらの核
燃料を原子炉で燃焼させたときの転換比は、原子
炉の炉型式、原子炉の出力規摸、燃料交換パター
ン等によつて異なるが、概ね0.6〜0.8の程度であ
る。 In any case, the fuel pellets used in each of the above-mentioned nuclear reactors are made entirely of nuclear fuel material with a uniform concentration, and the conversion ratio when these nuclear fuels are burned in a nuclear reactor is atomic. Although it varies depending on the reactor type, reactor output specifications, fuel exchange pattern, etc., it is approximately 0.6 to 0.8.
ところで、原子炉の炉型及び原子炉の出力規摸
を指定すると、核燃料物質の全炉心装荷量がほぼ
決定するが、核燃料物質の装荷量を一定としたと
き、従来技術の核燃料棒と本発明の核燃料棒とを
比較すると、後者のほうが高い転換比をうること
ができる。 By the way, by specifying the reactor type and reactor output scale, the total amount of nuclear fuel material loaded into the reactor core is approximately determined, but when the amount of nuclear fuel material loaded is constant, the nuclear fuel rods of the prior art and the present invention Compared to nuclear fuel rods, the latter can achieve a higher conversion ratio.
その理由は、定性的に以下のように説明でき
る。すなわち、例えば、３％濃縮ウランのペレツ
トの従来技術の核燃料棒と、本発明に基づく複合
ペレツトとして中央部が0.3％ウラン−235の劣化
ウランを配置し、井戸型空孔付円筒状ペレツト部
に４％の濃縮ウランを用い、平均濃縮度が３％に
して等価になるとする。一般的には、原子炉内の
核燃料棒は燃料ペレツトの外周部がその内部より
も核***反応が盛んに進行する。しかも、本発明
による複合核燃料ペレツトの外周部（４％濃縮ウ
ラン）は、従来技術の均一濃縮度ペレツト（３％
濃縮ウラン）の外周部よりも核***反応が余計に
進行し、このため複合核燃料ペレツトは、従来型
ペレツトに比較して、より高い中性子の空間密度
流束を形成する。一方、核親物質が核燃料物質に
転換する率は、中性子の空間密度流束と核親物質
の空間密度と燃料の燃焼時間との３因子の積に比
例し、他方、複合ペレツトの核親物質は、そのよ
うな高い濃縮度の核燃料物質に包囲されているこ
とから、より高い中性子の空間密度流束にさらさ
れて、従来技術の核燃料棒の場合の1.1〜1.3倍の
転換比がえられることになる。 The reason for this can be qualitatively explained as follows. That is, for example, a conventional nuclear fuel rod made of 3% enriched uranium pellets and a composite pellet based on the present invention with depleted uranium containing 0.3% uranium-235 in the center are arranged, and a cylindrical pellet with well-shaped holes is formed. Assume that 4% enriched uranium is used and the average enrichment is 3%. Generally, in a nuclear fuel rod in a nuclear reactor, the nuclear fission reaction progresses more actively on the outer periphery of the fuel pellet than on the inside. Furthermore, the outer periphery (4% enriched uranium) of the composite nuclear fuel pellet according to the present invention is different from that of the conventional homogeneous enrichment pellet (3% enriched uranium).
The fission reaction proceeds further than the outer periphery of the enriched uranium (enriched uranium), so composite nuclear fuel pellets form a higher spatial density flux of neutrons than conventional pellets. On the other hand, the rate at which nuclear parent material is converted into nuclear fuel material is proportional to the product of three factors: the spatial density flux of neutrons, the spatial density of nuclear parent material, and the combustion time of the fuel. Because they are surrounded by such highly enriched nuclear fuel material, they are exposed to a higher spatial density flux of neutrons, resulting in a conversion ratio of 1.1 to 1.3 times that of conventional nuclear fuel rods. It turns out.
さて、前記のような本発明で用いる複合構造の
核燃料ペレツトを製造するには、組合せる外側及
び内側各ペレツト組成燃料粉末を別々に所定形状
に成形して焼結し、各焼結体を嵌合する方法が一
般的であるが他の手順によつても製造することが
できる。 Now, in order to manufacture nuclear fuel pellets with a composite structure used in the present invention as described above, the outer and inner pellet composition fuel powders to be combined are separately formed into a predetermined shape and sintered, and each sintered body is fitted. Although this method is common, it can also be produced by other procedures.
第９図は、本発明に係る核燃料棒の他の実施例
を示す説明図である。燃料被覆管８の内部には二
種の核燃料ペレツト３０，３１が積層装填され、
両端でそれぞれ上部端栓１３及び下部端栓７によ
り密封される。燃料被覆管８の中央部に積層装填
される核燃料ペレツト３０は、前述したのと同様
のものであつて、上端面中央に井戸型空孔部を有
する有底円筒状の核燃料物質２２と、前記井戸型
空孔部に嵌合する核親物質２１とからなる複合構
造をなすものである。燃料被覆管８の両端近傍部
に装填される核燃料ペレツト３１は、前記のもの
と異なり、第１０図のような構造のものである。
すなわち、有底円筒状の核燃料物質２２からなる
ペレツトの井戸型空孔部２３に、FPを吸着し易
いゲツター材ペレツト２５を嵌合した複合構造の
ペレツトである。このような核燃料棒は、高い燃
焼度に対しても燃料破損を生じることなく原子炉
内で使用することができる点で、甚だ優れたもの
である。何故ならば、従来技術による円柱状ペレ
ツトと比較して高温のペレツト中心領域が欠如し
ており、このため燃料破損を生じる原因といわれ
ている被覆管内面のペレツトの半径方向クラツク
開口部の応力集中の程度が小さくなつてPCMIが
低減され、またFP用ゲツター材が組込まれたも
のについては、腐蝕性雰囲気として悪影響を及ぼ
すFPのうちの沃素やセシウムの濃度が低くなる
からである。 FIG. 9 is an explanatory diagram showing another embodiment of the nuclear fuel rod according to the present invention. Two types of nuclear fuel pellets 30 and 31 are stacked and loaded inside the fuel cladding tube 8.
It is sealed at both ends by an upper end plug 13 and a lower end plug 7, respectively. The nuclear fuel pellets 30 stacked and loaded in the center of the fuel cladding tube 8 are similar to those described above, and include a bottomed cylindrical nuclear fuel material 22 having a well-shaped hole in the center of the upper end surface, and It forms a composite structure consisting of a nucleophile material 21 that fits into a well-shaped cavity. The nuclear fuel pellets 31 loaded near both ends of the fuel cladding tube 8 are different from those described above and have a structure as shown in FIG. 10.
That is, the pellet has a composite structure in which a getter material pellet 25 that easily adsorbs FP is fitted into a well-shaped cavity 23 of a pellet made of a bottomed cylindrical nuclear fuel material 22. Such nuclear fuel rods are extremely superior in that they can be used in nuclear reactors even at high burn-up without fuel damage. This is because, compared to conventional cylindrical pellets, there is a lack of a high-temperature central region of the pellet, which causes stress concentration at the radial crack opening of the pellet on the inner surface of the cladding tube, which is said to be the cause of fuel failure. This is because the degree of PCMI is reduced, and in the case of a getter material for FP incorporated, the concentration of iodine and cesium in the FP, which have an adverse effect as a corrosive atmosphere, is lowered.
本発明は前記のように構成した核燃料棒である
から、高い転換比を発電用熱中性子原子炉で実現
でき、それによつて核燃料資源の有効利用を図る
ことができ、また、FPのゲツター材と組合せる
ことにより高い燃焼度を達成することができるな
ど、優れた経済性を有する核燃料棒を提供できる
ものである。 Since the present invention is a nuclear fuel rod configured as described above, a high conversion ratio can be realized in a thermal neutron reactor for power generation, thereby making it possible to effectively utilize nuclear fuel resources. By combining these elements, it is possible to achieve a high burnup, thereby providing a nuclear fuel rod with excellent economic efficiency.
第１図は増殖炉のモデル図、第２図はそれに使
われる核燃料棒の説明図、第３図は本発明で用い
る核燃料ペレツトの一例を示す図、第４図、第５
図、第６図、第７図は本発明で用いられる他のペ
レツト構造の説明図、第８図は本発明の一実施例
を示す説明図、第９図は本発明の他の実施例を示
す説明図、第１０図は第９図に示す核燃料棒に用
いる核燃料ペレツトの一例を示す説明図である。
７……下部端栓、８……燃料被覆管、９，１
２，３０，３１……核燃料ペレツト、１３……上
部端栓、２１……核親物質、２２……核燃料物
質、２３……井戸型空孔部、２５……ゲツター材
ペレツト。
Figure 1 is a model diagram of a breeder reactor, Figure 2 is an explanatory diagram of nuclear fuel rods used in it, Figure 3 is a diagram showing an example of nuclear fuel pellets used in the present invention, Figures 4 and 5.
6 and 7 are explanatory diagrams of other pellet structures used in the present invention, FIG. 8 is an explanatory diagram showing one embodiment of the present invention, and FIG. 9 is an explanatory diagram showing another embodiment of the present invention. FIG. 10 is an explanatory diagram showing an example of nuclear fuel pellets used in the nuclear fuel rod shown in FIG. 9. 7...Lower end plug, 8...Fuel cladding tube, 9,1
2, 30, 31... Nuclear fuel pellet, 13... Upper end plug, 21... Nuclear parent material, 22... Nuclear fuel material, 23... Well-shaped cavity, 25... Getter material pellet.
Claims (1)
内に積層装填され、該燃料被覆管の両端が密封さ
れている核燃料棒において、前記円柱状核燃料ペ
レツトは、上端面中央に井戸型空孔部を有する有
底円筒状の核燃料物質と、前記井戸型空孔部に嵌
合する核親物質とからなる複合構造をなしている
ことを特徴とする資源有効利用型核燃料棒。 ２ 核燃料物質に形成された井戸型空孔部の形状
が、直円柱状、回転半楕円形状、または回転逆梯
形状である特許請求の範囲第１項記載の核燃料
棒。 ３ 井戸型空孔部の深さが核燃料ペレツト高さの
約1/4〜3/4である特許請求の範囲第２項記載の核
燃料棒。 ４ 円柱状核燃料ペレツトは、その下端直径が上
端直径よりも小である特許請求の範囲第１項、第
２項、または第３項記載の核燃料棒。 ５ 多数個の円柱状核燃料ペレツトが燃料被覆管
内に積層装填され、該燃料被覆管の両端が密封さ
れている核燃料棒において、前記円柱状核燃料ペ
レツトは燃料被覆管の長さ方向中央部に装填され
る核燃料ペレツトが、上端面中央に井戸型空孔部
を有する有底円筒状の核燃料物質と、前記井戸型
空孔部に嵌合する核親物質とからなる複合構造を
なし、また、燃料被覆管の両端近傍部に装填され
る核燃料ペレツトが、核燃料物質からなる有底円
筒状のペレツトの井戸型空孔部に、核***生成物
を吸着し易いゲツター材料を挿入した複合構造を
なしていることを特徴とする資源有効利用型核燃
料棒。[Scope of Claims] 1. In a nuclear fuel rod in which a large number of cylindrical nuclear fuel pellets are stacked and loaded in a fuel cladding tube, and both ends of the fuel cladding tube are sealed, the cylindrical nuclear fuel pellets have a well in the center of the upper end surface. A resource-efficient nuclear fuel rod characterized by having a composite structure consisting of a bottomed cylindrical nuclear fuel material having a shaped cavity and a nuclear parent material fitted into the well-shaped cavity. 2. The nuclear fuel rod according to claim 1, wherein the well-shaped cavity formed in the nuclear fuel material has a shape of a right cylinder, a rotating semi-ellipse, or a rotating inverted ladder. 3. The nuclear fuel rod according to claim 2, wherein the depth of the well-shaped cavity is about 1/4 to 3/4 of the height of the nuclear fuel pellet. 4. The nuclear fuel rod according to claim 1, 2, or 3, wherein the cylindrical nuclear fuel pellet has a lower end diameter smaller than an upper end diameter. 5. In a nuclear fuel rod in which a large number of cylindrical nuclear fuel pellets are stacked and loaded in a fuel cladding tube, and both ends of the fuel cladding tube are sealed, the cylindrical nuclear fuel pellets are loaded in the longitudinal center of the fuel cladding tube. The nuclear fuel pellet has a composite structure consisting of a bottomed cylindrical nuclear fuel material having a well-shaped hole in the center of the upper end surface, and a nuclear parent material that fits into the well-shaped hole, and has a fuel cladding. The nuclear fuel pellets loaded in the vicinity of both ends of the tube have a composite structure in which a getter material that easily adsorbs nuclear fission products is inserted into the well-shaped hole of the bottomed cylindrical pellet made of nuclear fuel material. A nuclear fuel rod that makes efficient use of resources.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57007323A JPS58124984A (en) | 1982-01-20 | 1982-01-20 | Nuclear fuel rod for effectively utilizing resource |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57007323A JPS58124984A (en) | 1982-01-20 | 1982-01-20 | Nuclear fuel rod for effectively utilizing resource |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58124984A JPS58124984A (en) | 1983-07-25 |
| JPS6322550B2 true JPS6322550B2 (en) | 1988-05-12 |
Family
ID=11662756
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57007323A Granted JPS58124984A (en) | 1982-01-20 | 1982-01-20 | Nuclear fuel rod for effectively utilizing resource |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58124984A (en) |
-
1982
- 1982-01-20 JP JP57007323A patent/JPS58124984A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58124984A (en) | 1983-07-25 |
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