JPH0517511B2 - - Google Patents
Info
- Publication number
- JPH0517511B2 JPH0517511B2 JP58060964A JP6096483A JPH0517511B2 JP H0517511 B2 JPH0517511 B2 JP H0517511B2 JP 58060964 A JP58060964 A JP 58060964A JP 6096483 A JP6096483 A JP 6096483A JP H0517511 B2 JPH0517511 B2 JP H0517511B2
- Authority
- JP
- Japan
- Prior art keywords
- pellets
- concentration
- enrichment
- interface
- nuclear fuel
- 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
- 239000008188 pellet Substances 0.000 claims description 40
- 239000003758 nuclear fuel Substances 0.000 claims description 15
- 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 12
- 238000005253 cladding Methods 0.000 claims description 8
- 230000004323 axial length Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- OOAWCECZEHPMBX-UHFFFAOYSA-N oxygen(2-);uranium(4+) Chemical compound [O-2].[O-2].[U+4] OOAWCECZEHPMBX-UHFFFAOYSA-N 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- FCTBKIHDJGHPPO-UHFFFAOYSA-N uranium dioxide Inorganic materials O=[U]=O FCTBKIHDJGHPPO-UHFFFAOYSA-N 0.000 description 2
- 238000005452 bending Methods 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- UTDLAEPMVCFGRJ-UHFFFAOYSA-N plutonium dihydrate Chemical compound O.O.[Pu] UTDLAEPMVCFGRJ-UHFFFAOYSA-N 0.000 description 1
- FLDALJIYKQCYHH-UHFFFAOYSA-N plutonium(IV) oxide Inorganic materials [O-2].[O-2].[Pu+4] FLDALJIYKQCYHH-UHFFFAOYSA-N 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Description
【発明の詳細な説明】 〔発明の技術分野〕 本発明は原子炉における核燃料棒に係る。[Detailed description of the invention] [Technical field of invention] The present invention relates to nuclear fuel rods in nuclear reactors.
核燃料棒は、被覆管内に二酸化ウランUO2、ま
たは二酸化ウランUO2と二酸化プルトニウム
PuO2の混合物を焼結して形成した円柱状のペレ
ツトを充填封入して構成されている。
Nuclear fuel rods contain uranium dioxide UO 2 or uranium dioxide UO 2 and plutonium dioxide in the cladding tube.
It is constructed by filling and enclosing cylindrical pellets formed by sintering a PuO 2 mixture.
上記構成の核燃料棒を多数装填して成る燃料集
合体を炉心に装荷して原子炉を運転するが、この
際燃料集合体、従つて核燃料棒軸方向に出力分布
を生じる。 A nuclear reactor is operated by loading a fuel assembly comprising a large number of nuclear fuel rods having the above configuration into a reactor core. At this time, a power distribution occurs in the axial direction of the fuel assembly and therefore the nuclear fuel rods.
而して、核燃料棒の健全性維持、原子炉運転の
安全性確保の点から、前記の軸方向出力分布は出
来るだけ平坦であることが望ましい。 From the standpoint of maintaining the integrity of the nuclear fuel rods and ensuring the safety of nuclear reactor operation, it is desirable that the axial power distribution be as flat as possible.
軸方向出力分布を平坦化させるため、従来次の
ような手段がとられて来た。その一つは、出力分
布が高くなる部分に低濃縮度のペレツトを充填す
るものである。 Conventionally, the following measures have been taken to flatten the axial power distribution. One of these is to fill the areas where the power distribution becomes high with pellets of low concentration.
この種の核燃料棒にあつては、巨視的に見れば
軸方向出力分布の平坦化は達成し得るものの、濃
縮度境界面において隣接するペレツトに発熱量に
不連続を生じる。すなわち、濃縮度境界面に隣接
する高濃縮度ペレツトの発熱量は、同じく低濃縮
度ペレツトのそれより大きい。そのため、高濃縮
度側ペレツトと低濃縮度側の熱膨張量に差を生じ
る。それらの熱膨張量が、各ペレツト外周と被覆
管内周との間隙を超えた時、被覆管はペレツトに
より押広げられるが、その径方向変形量は高濃縮
度側で大きく、低濃縮度側で小さい。そのため、
被覆管には軸方向の曲げ応力分布が生じ、濃縮度
境界面近傍には応力分布の鋭いピーを生じること
となる。 In this type of nuclear fuel rod, although flattening of the axial power distribution can be achieved from a macroscopic perspective, discontinuity occurs in the calorific value of adjacent pellets at the enrichment boundary. That is, the calorific value of the high enrichment pellets adjacent to the enrichment interface is also greater than that of the low enrichment pellets. Therefore, there is a difference in the amount of thermal expansion between the pellets on the high enrichment side and the pellets on the low enrichment side. When the amount of thermal expansion exceeds the gap between the outer periphery of each pellet and the inner periphery of the cladding tube, the cladding tube is expanded by the pellets, but the amount of radial deformation is large on the high enrichment side and large on the low enrichment side. small. Therefore,
An axial bending stress distribution occurs in the cladding tube, and a sharp peak in the stress distribution occurs near the enrichment interface.
このような問題を解決するため、濃縮度境界面
近傍のペレツトを小径とし、これに金属リングを
係合させて他部のペレツトと外径と等しくするこ
とが提案されている。この種の核燃料棒にあつて
は、ペレツトを小径とした分だけ発熱量、熱膨張
量が小さくなり、応力分布の濃縮度境界面近傍に
おけるピークを抑制し得るが、境界面近傍のペレ
ツトを別製したり、特殊の加工を施したりするこ
とは不経済であり、好ましくない。さらに、金属
リングの材料として何が適切であるかは、今後の
研究、実験にまたねばならず、実用化はかなり遠
い将来のことと考えられる。 In order to solve this problem, it has been proposed to reduce the diameter of the pellet near the enrichment boundary and engage it with a metal ring so that the outside diameter is equal to that of the pellet in other areas. In this type of nuclear fuel rod, the calorific value and thermal expansion are reduced by making the pellets smaller in diameter, and the peak of the stress distribution near the enrichment boundary can be suppressed, but the pellets near the boundary are Manufacturing or special processing is uneconomical and undesirable. Furthermore, future research and experiments are required to determine what material is suitable for the metal ring, and practical use is considered to be quite far in the future.
本発明は上記の事情に基きなされたもので、軸
方向出力分布を平坦化させたものであつて、安価
に供給し得る核燃料棒を得ることを目的としてい
る。
The present invention was made based on the above circumstances, and an object of the present invention is to obtain a nuclear fuel rod that has a flattened axial power distribution and that can be supplied at low cost.
本発明においては、濃縮度境界近傍の数箇の高
濃縮ペレツトを中心に軸方向小孔を有する中空筒
状とし、それらの中濃縮度境界面に隣接するもの
には、前記の小孔にガドリニアGd2O3を含有する
小柱状のペレツトを充填して核燃料棒を構成して
前記目的を達成している。
In the present invention, several highly concentrated pellets near the enrichment boundary are formed into hollow cylinders having small axial holes in the center, and those adjacent to the middle enrichment boundary are filled with gadolinia in the small holes. The above objective is achieved by constructing a nuclear fuel rod by filling small columnar pellets containing Gd 2 O 3 .
第１図は本発明の一実施例を示し、第２図はそ
の単位長当り発熱量を第１図と対比して示すグラ
フである。第１図において、濃縮度境界面−
より左側に位置する高濃縮度側ペレツトHpの中、
境界面−近傍に位置するHp1〜Hp3の３箇を
中心に軸方向小孔Ｏを有する中空筒状とする。さ
らにその境界面−に隣接するペレツトHp3の
小孔には、ガドリニアを含有する小柱状のペレツ
トPsを充填する。なお、図中、Lpは低濃縮度ペ
レツト、Ｃは被覆管を示している。
FIG. 1 shows an embodiment of the present invention, and FIG. 2 is a graph showing the amount of heat generated per unit length in comparison with FIG. 1. In Figure 1, the enrichment boundary surface -
In the high concentration side pellet Hp located on the left side,
It has a hollow cylindrical shape with small axial holes O centered on three points Hp 1 to Hp 3 located near the boundary surface. Furthermore, the small pores of the pellet Hp3 adjacent to the boundary surface are filled with small columnar pellets Ps containing gadolinia. In the figure, Lp indicates a low concentration pellet, and C indicates a cladding tube.
上記構成の本発明核燃料棒においては、境界面
近傍の高濃縮度側ペレツトが中空筒状とされてい
るため、発熱量が少く、その上境界面に隣接する
ペレツトの小孔にはガドリニアを含有する小柱状
のペレツトが充填されているので、第２図に曲線
C1，C2で示すように、境界面近傍における出力
の不連続は緩和される。なお、第２図中点線の曲
線C1′，C2′は従来の核燃料棒を示す。 In the nuclear fuel rod of the present invention having the above configuration, the high enrichment side pellet near the interface has a hollow cylindrical shape, so the calorific value is small, and furthermore, the small pores of the pellet adjacent to the interface contain gadolinia. The curve shown in Figure 2 is filled with small columnar pellets.
As shown by C 1 and C 2 , the discontinuity in the output near the interface is alleviated. Note that dotted curves C 1 ′ and C 2 ′ in FIG. 2 indicate conventional nuclear fuel rods.
本発明は上記実施例のみに限定されない。例え
ば、中空筒状とするペレツトの数は３箇でなくも
よい。前記の実施例で３箇としたのは、水を減速
材とする原子炉においては、熱中性子束が影響を
受けるのは、主として境界面から約３cmの範囲内
であり、ペレツトの軸長が約１cmであるからであ
つて、減速材、ペレツト軸長によつて任意に定め
てもよい。また、境界面に隣接する中空筒状のペ
レツトへのガドリニア含有ペレツトの充填も、場
合によつては省略してもよい。 The present invention is not limited to the above embodiments. For example, the number of pellets in the hollow cylindrical shape may not be three. The reason why there are three points in the above example is that in a nuclear reactor that uses water as a moderator, the thermal neutron flux is mainly affected within a range of about 3 cm from the boundary surface, and the axial length of the pellet is This is approximately 1 cm, and may be arbitrarily determined depending on the moderator and pellet axial length. Furthermore, the filling of the gadolinia-containing pellets into the hollow cylindrical pellets adjacent to the boundary surface may be omitted depending on the case.
上記から明らかなように、本発明によれば、濃
縮度境界近傍における発熱量の不連続を抑制し得
るので、被覆管の軸方向応力分布の前記部位にお
けるピークを抑制することができ、核燃料棒の健
全性維持上、原子炉運転の安全性確保上きわめて
有利である。さらに、中空筒状のペレツトは、す
でにプラントにおける照射実績を持つものである
から、本発明を不安なく実用化することができ
る。また、経済的にも有利である。さらに、境界
面を非破壊検査で容易に識別できるので、信頼性
の高い核燃料棒となし得る。
As is clear from the above, according to the present invention, it is possible to suppress the discontinuity in the calorific value near the enrichment boundary, so it is possible to suppress the peak of the axial stress distribution of the cladding tube at the said portion, and the nuclear fuel rod This is extremely advantageous in terms of maintaining the integrity of nuclear reactors and ensuring the safety of nuclear reactor operation. Furthermore, since hollow cylindrical pellets have already been irradiated in plants, the present invention can be put to practical use without any concerns. It is also economically advantageous. Furthermore, since the interface can be easily identified by non-destructive inspection, a highly reliable nuclear fuel rod can be obtained.
第１図は本発明一実施例の縦断面図、第２図は
その効果を説明するためのグラフである。
Ｃ……被覆管、Hp，Hp1〜Hp3……高濃縮度
ペレツト、Lp……低濃縮度ペレツト、Ps……ガ
ドリニア含有ペレツト、−……濃縮度境界
面。
FIG. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, and FIG. 2 is a graph for explaining its effects. C...Claying tube, Hp, Hp1 to Hp3 ...High enrichment pellets, Lp...Low enrichment pellets, Ps...Gadolinia-containing pellets, -...Enrichment interface.
Claims (1)
ツトとを充填封入してなるものにおいて、高濃縮
ペレツトの中濃縮境界面近傍の数箇を中空筒状と
したことを特徴とする核燃料棒。 ２ 被覆管内に高濃縮度ペレツトと低濃縮度ペレ
ツトとを充填封入してなるものにおいて、高濃縮
ペレツトの中濃縮境界面近傍の数箇を中空筒状と
し、さらにその濃縮度境界面に隣接したペレツト
の中空部には、ガドリニア含有の小柱状のペレツ
トを充填したことを特徴とする核燃料棒。[Scope of Claims] 1. A cladding tube filled with high-concentration pellets and low-concentration pellets, characterized in that several portions near the middle-concentration interface of the high-concentration pellets are hollow cylindrical. nuclear fuel rods. 2 In a cladding tube filled with high-concentration pellets and low-concentration pellets, several sections near the middle-to-concentration interface of the high-concentration pellets are made hollow cylinders, and furthermore, several sections near the middle-to-concentration interface of the high-concentration pellets are made into hollow cylinders, and the sections adjacent to the enrichment interface are made into hollow cylinders. A nuclear fuel rod characterized in that the hollow part of the pellet is filled with small columnar pellets containing gadolinia.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58060964A JPS59187289A (en) | 1983-04-08 | 1983-04-08 | Nuclear fuel rod |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58060964A JPS59187289A (en) | 1983-04-08 | 1983-04-08 | Nuclear fuel rod |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59187289A JPS59187289A (en) | 1984-10-24 |
| JPH0517511B2 true JPH0517511B2 (en) | 1993-03-09 |
Family
ID=13157601
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58060964A Granted JPS59187289A (en) | 1983-04-08 | 1983-04-08 | Nuclear fuel rod |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59187289A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4678629A (en) * | 1985-09-05 | 1987-07-07 | Westinghouse Electric Corp. | Nuclear fuel pellet containing gadolinia |
-
1983
- 1983-04-08 JP JP58060964A patent/JPS59187289A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59187289A (en) | 1984-10-24 |
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