JPH02167496A - Nuclear fuel assembly - Google Patents
Nuclear fuel assemblyInfo
- Publication number
- JPH02167496A JPH02167496A JP63320692A JP32069288A JPH02167496A JP H02167496 A JPH02167496 A JP H02167496A JP 63320692 A JP63320692 A JP 63320692A JP 32069288 A JP32069288 A JP 32069288A JP H02167496 A JPH02167496 A JP H02167496A
- Authority
- JP
- Japan
- Prior art keywords
- end plug
- fuel
- tie plate
- fuel element
- fuel assembly
- 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.)
- Pending
Links
- 239000003758 nuclear fuel Substances 0.000 title claims description 10
- 239000000446 fuel Substances 0.000 claims abstract description 49
- 125000006850 spacer group Chemical group 0.000 claims abstract description 6
- 238000003780 insertion Methods 0.000 abstract description 8
- 230000037431 insertion Effects 0.000 abstract description 8
- 230000000712 assembly Effects 0.000 description 5
- 238000000429 assembly Methods 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000007689 inspection Methods 0.000 description 4
- 239000002915 spent fuel radioactive waste Substances 0.000 description 4
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000007787 solid Substances 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)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、原子炉で使用された燃料集合体の検査、解体
に係り、特に燃料要素単体を、該集合体から容易に引抜
くために好適な核燃料集合体に関するものである。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the inspection and disassembly of fuel assemblies used in nuclear reactors, and in particular, to the inspection and disassembly of fuel assemblies used in nuclear reactors, and in particular to the inspection and dismantling of fuel assemblies used in nuclear reactors, and in particular to the inspection and disassembly of fuel assemblies used in nuclear reactors. The present invention relates to a preferred nuclear fuel assembly.
［従来の技術］ 第４図は、従来例の核燃料集合体の構成略示図である。[Conventional technology] FIG. 4 is a schematic diagram showing the structure of a conventional nuclear fuel assembly.
この図において、■は、上部タイプレート、２は、下部
タイプレート、３は、核燃料要素、５は、スペーサ、６
ａは、下部端栓である。In this figure, ■ is an upper tie plate, 2 is a lower tie plate, 3 is a nuclear fuel element, 5 is a spacer, and 6 is a
a is the lower end plug.
該集合体は、格子状に規則的に配置された長尺の複数本
の燃料要素３を中間部でスペーサ５で保持し、上部タイ
プレート１および下部タイプレート２で支持することに
より組立てられている。The assembly is assembled by holding a plurality of elongated fuel elements 3 regularly arranged in a lattice shape with spacers 5 in the middle and supporting them with an upper tie plate 1 and a lower tie plate 2. There is.
原子炉内で使用した燃料集合体を、燃料要素単位で検査
する場合には、まず、上部タイプレート等を取外し、燃
料要素３を集合体から引抜く必要がある。When inspecting a fuel assembly used in a nuclear reactor in units of fuel elements, it is first necessary to remove the upper tie plate and the like and pull out the fuel element 3 from the assembly.
第２図は、従来例に係る下部タイプレート２と嵌合する
燃料要素３の、下部端栓６ａの形状を示す図である。FIG. 2 is a diagram showing the shape of a lower end plug 6a of a fuel element 3 that fits into a lower tie plate 2 according to a conventional example.
第２図において、燃料要素３の下部端栓６ａの直系Ｄ□
と下部端栓６ａの下部タイプレート２への挿入孔の直系
Ｄ２は共に円柱状に嵌合する構造となっている。また、
その嵌合部の間隔Ｌ＝１／２（Ｄ２−Ｄｌ）は、わずか
に０．１ｍｍである。In FIG. 2, the direct line D□ of the lower end plug 6a of the fuel element 3
and the direct line D2 of the insertion hole of the lower end plug 6a into the lower tie plate 2 are structured to fit together in a cylindrical shape. Also,
The distance L=1/2 (D2-Dl) between the fitting parts is only 0.1 mm.
上記従来技術の集合体では、原子炉内で使用中に下部タ
イプレート２と下部端栓６ａの嵌合部で固着が生じてい
た。従って、燃料要素引抜きの際に機械的な方法により
衝撃を与えて固着状態を解除する方法を用いていた。更
には、時開６０−２０２３９４号公報の記載のように、
使用済燃料集合体の下部タイプレート２を加熱して、下
部タイプレート２と下部端栓６ａとの熱膨張量差を利用
して下部タイプレート２と下部端栓６ａの固着を解くよ
うになっていた。In the above-mentioned prior art assembly, sticking occurred at the fitting portion between the lower tie plate 2 and the lower end plug 6a during use in a nuclear reactor. Therefore, when pulling out the fuel element, a method has been used in which a mechanical impact is applied to release the stuck state. Furthermore, as described in Jikai No. 60-202394,
The lower tie plate 2 of the spent fuel assembly is heated to release the adhesion between the lower tie plate 2 and the lower end plug 6a by utilizing the difference in thermal expansion between the lower tie plate 2 and the lower end plug 6a. was.
［発明が解決しようとする課題］
上記従来の燃料集合体は、原子炉内で使用中に下部タイ
プレートの下部端栓挿入孔と燃料要素下部端栓の嵌合部
で熱膨張量の違いにより間隔ができ、その間隔に原子炉
水中のクラッドが付着する。[Problems to be Solved by the Invention] During use in a nuclear reactor, the conventional fuel assembly described above experiences thermal expansion at the fitting portion between the lower end plug insertion hole of the lower tie plate and the lower end plug of the fuel element. A gap is formed, and crud in the reactor water adheres to the gap.
また、ジルカロイ−２合金で造られている燃料要素下部
端栓の表面に腐食によって酸化膜が生成される。そして
原子炉運転停止燃料の温度低下とともに下部タイプレー
トと下部端栓の嵌合部は、狭い間隙部に異物を挿入した
まま収納するために固着状態となる。従来の集合体では
、その固着に対する配慮がなされておらず燃料要素を集
合体から引抜くときこの固着を解除するのに過大な負荷
を要するので、燃料要素の損傷を引起こす恐れがあった
・
本発明の目的は、上記の問題点を取除き、使用済燃料集
合体から燃料要素の引抜きが容易な集合体を提供するこ
とにある。Additionally, an oxide film is formed on the surface of the lower end plug of the fuel element, which is made of Zircaloy-2 alloy, due to corrosion. Then, as the temperature of the reactor shutdown fuel decreases, the fitting portion between the lower tie plate and the lower end plug becomes stuck in order to accommodate the foreign object inserted into the narrow gap. In conventional assemblies, no consideration was given to the sticking of fuel elements, and when pulling the fuel element out of the assembly, an excessive load was required to release this sticking, which could cause damage to the fuel element. An object of the present invention is to eliminate the above-mentioned problems and provide a spent fuel assembly in which fuel elements can be easily extracted from the spent fuel assembly.
［課題を解決するための手段］
上記課題を解決するための本発明の核燃料集合体の構成
は、複数本の燃料要素をスペーサを介して格子状に配設
し、それら燃料要素の」二部および下部端栓を、上部お
よび下部タイプレートによって固定保持してなる核燃料
集合体において、核燃料要素の下部端栓嵌合部を、下方
ほど細くなる、傾斜角１〜３度のテーパ状にするととも
に、下部タイプレート嵌合部を、前記下部端栓嵌合部と
同一傾斜角のテーパ状にするようにしたことである［作
用］
燃料集合体の下部タイプレートの下部端栓挿入孔と下部
端栓との嵌合部で固着が生じ易い。この固着の主な原因
は、燃料要素下部端栓の表面腐食である。特に、この下
部端栓に使用されているジルカロイ−２合金は腐食部分
の体積が約２倍になる性質をもっている。因に、下部タ
イプレートの下部端栓挿入孔と下部端栓との嵌合部の間
隙（Ｌ）を一般に使用されている０、１ｍｍとした集合
体において、原子炉で４サイクル照射後下部端栓表面の
腐食厚さが１サイクル当り２５μｍ成長するとすれば、
上記嵌合部の間隙がなくなり固着状態となると予想され
る。[Means for Solving the Problems] The structure of the nuclear fuel assembly of the present invention for solving the above problems is such that a plurality of fuel elements are arranged in a lattice shape via spacers, and two parts of the fuel elements are arranged in a lattice shape. and a nuclear fuel assembly in which a lower end plug is fixedly held by an upper and a lower tie plate, the lower end plug fitting portion of the nuclear fuel element is tapered at an inclination angle of 1 to 3 degrees, becoming narrower toward the bottom; , the lower tie plate fitting part is tapered at the same angle of inclination as the lower end plug fitting part [Function] The lower end plug insertion hole and the lower end of the lower tie plate of the fuel assembly Sticking tends to occur at the fitting part with the plug. The main cause of this sticking is surface corrosion of the fuel element lower end plug. In particular, the Zircaloy-2 alloy used in this lower end plug has the property of approximately doubling the volume of the corroded portion. Incidentally, in an assembly where the gap (L) at the fitting part between the lower end plug insertion hole of the lower tie plate and the lower end plug is set to 0.1 mm, which is commonly used, the lower end after 4 cycles of irradiation in a nuclear reactor. Assuming that the corrosion thickness on the plug surface grows by 25 μm per cycle,
It is expected that the gap between the fitting portions will disappear and a fixed state will result.
下部端栓と下部タイプレートの下部端栓挿入孔とに下向
きに円錐状の傾斜を設けることにより、上記嵌合部の摩
擦力が小さくなるので固着状態においても下部端栓を上
方に引き上げたとき抵抗なく燃料要素を集合体から引抜
くことができるようになる。By providing a downward conical slope between the lower end plug and the lower end plug insertion hole of the lower tie plate, the frictional force at the fitting portion is reduced, so even when the lower end plug is stuck, when the lower end plug is pulled upward. The fuel element can now be pulled out of the assembly without resistance.
つぎに、本発明で提案する最適な傾斜角について、実験
結果に基づいて説明する。Next, the optimal inclination angle proposed by the present invention will be explained based on experimental results.
傾斜構造の嵌合部模擬試験片を下記のように製作した。A simulating test piece of a fitting part with an inclined structure was manufactured as follows.
傾斜角αが０度（ストレート）、１度、３度および５度
のものを各々５個宛を、温度５００℃、圧力１００ｋｇ
／ｃｉのオートクレーブ中に２４時間浸漬し、酸化膜成
長法により、下部端栓部を下部タイプレート部に固着さ
せた。これら試験片を取出して、傾斜角α２０度の場合
の引抜力の平均値を基準（１００％）として、α２１度
、３度、５度の各々の引抜力の平均値をプロットした結
果が、第３図である。5 pieces each with inclination angle α of 0 degrees (straight), 1 degree, 3 degrees, and 5 degrees, temperature 500℃, pressure 100kg
/ci autoclave for 24 hours, and the lower end plug was fixed to the lower tie plate by an oxide film growth method. These test pieces were taken out, and the average value of the pulling force at the angle of α of 21 degrees, 3 degrees, and 5 degrees was plotted using the average value of the pulling force at the inclination angle of α of 20 degrees as the standard (100%). Figure 3.
第３図かられかるように、傾斜角＝工度でも、引抜力は
急激に低下し、３度附近で、はぼ一定値（約３０％）を
保つようになる。As can be seen from FIG. 3, even when the angle of inclination is equal to the work force, the pulling force decreases rapidly and comes to maintain a constant value (approximately 30%) around 3 degrees.
一方、この傾斜角が大きくなると、炉内で使用中の集合
体の燃料要素に流力振動が生じるようになり、不具合と
なるので、第３図の結果を勘案して、最適の傾斜角度は
、１〜３度の範囲を提案した。On the other hand, if this angle of inclination becomes large, fluid vibrations will occur in the fuel elements of the assembly being used in the reactor, resulting in a problem. Therefore, taking into account the results shown in Figure 3, the optimum angle of inclination is , suggested a range of 1 to 3 degrees.
［実施例］ 以下、本発明の一実施例を第１図を用いて説明する。[Example] An embodiment of the present invention will be described below with reference to FIG.
第１図は、本発明の一実施例に係り、下部端栓部とその
嵌合部の下部タイプレートに傾斜角度（α）を設けた断
面図である。FIG. 1 is a cross-sectional view in which a lower end plug and a lower tie plate of a fitting portion thereof are provided with an inclination angle (α) according to an embodiment of the present invention.
第１図の構成は、２は、下部タイプレート、３は、燃料
要素、６ｂは、下部端栓、７は、下部端栓嵌合部、８は
、下部タイプレート嵌合部、αは、傾斜角である。すな
わち、下部端栓と下部タイプレートとの嵌合部７および
８は等しい傾斜角度αで接触する構造となっている。In the configuration shown in FIG. 1, 2 is a lower tie plate, 3 is a fuel element, 6b is a lower end plug, 7 is a lower end plug fitting part, 8 is a lower tie plate fitting part, α is It is the angle of inclination. That is, the fitting portions 7 and 8 between the lower end plug and the lower tie plate are configured to contact each other at the same inclination angle α.
いま、傾斜角を３度にした時の動作についてみると、原
子炉内で使用中に燃料要素３の下部端栓６ｂ表面が腐食
、し、下部タイプレート２との嵌合部７および８で固着
状態になったとしても、この傾斜角３度のために、嵌合
部の摩擦力が小さいので、下部端栓部を上方に引上げる
ことによって円滑に燃料要素３を燃料集合体の下部タイ
プレート２から引抜くことができる。Now, looking at the operation when the inclination angle is 3 degrees, the surface of the lower end plug 6b of the fuel element 3 corroded during use in the reactor, and the fitting parts 7 and 8 with the lower tie plate 2 corroded. Even if it becomes stuck, the frictional force at the fitting part is small due to the 3 degree inclination angle, so by pulling the lower end plug upward, the fuel element 3 can be smoothly inserted into the lower type of fuel assembly. It can be extracted from rate 2.
本実施例の効果は、引抜きのための力は、微力でよいの
で、下部端栓も、下部タイプレートも傷つけることなく
、かつ作業効率を向上することができる。The advantage of this embodiment is that only a small amount of force is required for pulling it out, so that neither the lower end plug nor the lower tie plate is damaged, and the work efficiency can be improved.
［発明の効果］
本発明によれば、下部タイプレートの燃料要素下部端栓
挿入孔と下部端栓部とに一定傾斜角を設けることにより
、下部端栓の表面に腐食が生じても挿入孔内での下部端
栓の移動は円滑にできるので、燃料集合体から燃料要素
を引抜くことは容易となる。腐食による固着を解除する
ための特別な装置・施設の増設の必要がなく、これに要
する人工費も節減することができる。また、引抜くため
に過大な荷重をかける必要がないので、燃料集合体を傷
つけることがなく、作業を安全に実施することができる
。[Effects of the Invention] According to the present invention, by providing a constant inclination angle between the fuel element lower end plug insertion hole and the lower end plug portion of the lower tie plate, even if the surface of the lower end plug is corroded, the insertion hole remains intact. Since the lower end plug can be smoothly moved within the fuel assembly, it is easy to pull out the fuel element from the fuel assembly. There is no need to add special equipment or facilities to release the fixation caused by corrosion, and the labor costs required for this can also be reduced. Further, since it is not necessary to apply an excessive load to pull out the fuel assembly, the work can be carried out safely without damaging the fuel assembly.
以上要するに、使用済燃料集合体から燃料要素の引抜き
が容易で、安全な燃料集合体を提供することができる。In short, it is possible to provide a safe fuel assembly in which the fuel elements can be easily extracted from the spent fuel assembly.
第１図は、本発明の一実施例に係り、燃料要素下部端栓
と下部タイプレートとの嵌合部詳細図、第２図は、従来
例の下部端栓と下部タイプレート−７＝
との嵌合部詳細図、第３図は、燃料要素下部端栓の立体
角（傾斜角）と燃料要素引抜力の関係図、第４図は、従
来例の燃料集合体の構成略示図である。
〈符号の説明〉
１・・・上部タイプレート、２・・・下部タイプレート
、３・・・燃料要素、５・・・スペーサ、６ａ、６ｂ・
・・下部端栓、７・・・下部端栓嵌合部、８・・・下部
タイプレート嵌合部、Ｌ・・・嵌合部の間隙、α・・・
下部端栓中心線に対する傾斜角。FIG. 1 is a detailed view of the fitting portion between the lower end plug of the fuel element and the lower tie plate according to an embodiment of the present invention, and FIG. 2 is a detailed view of the fitting portion between the lower end plug and the lower tie plate of the conventional example. Fig. 3 is a diagram showing the relationship between the solid angle (inclination angle) of the fuel element lower end plug and the fuel element pulling force, and Fig. 4 is a schematic diagram of the structure of a conventional fuel assembly. be. <Explanation of symbols> 1... Upper tie plate, 2... Lower tie plate, 3... Fuel element, 5... Spacer, 6a, 6b.
...Lower end plug, 7...Lower end plug fitting part, 8...Lower tie plate fitting part, L...Gap between fitting parts, α...
Inclination angle relative to the centerline of the bottom end plug.
Claims (1)
し、それら燃料要素の上部および下部端栓を、上部およ
び下部タイプレートによって固定保持してなる核燃料集
合体において、核燃料要素の下部端栓嵌合部を、下方ほ
ど細くなる、傾斜角１〜３度のテーパ状にするとともに
、下部タイプレート嵌合部を、前記下部端栓嵌合部と同
一傾斜角のテーパ状にしたことを特徴とする核燃料集合
体。1. In a nuclear fuel assembly in which a plurality of fuel elements are arranged in a lattice shape via spacers, and the upper and lower end plugs of the fuel elements are fixedly held by upper and lower tie plates, the lower part of the nuclear fuel element is The end plug fitting part has a tapered shape with an inclination angle of 1 to 3 degrees, which becomes narrower toward the bottom, and the lower tie plate fitting part has a tapered shape with the same inclination angle as the lower end plug fitting part. A nuclear fuel assembly featuring:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63320692A JPH02167496A (en) | 1988-12-21 | 1988-12-21 | Nuclear fuel assembly |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63320692A JPH02167496A (en) | 1988-12-21 | 1988-12-21 | Nuclear fuel assembly |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02167496A true JPH02167496A (en) | 1990-06-27 |
Family
ID=18124278
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63320692A Pending JPH02167496A (en) | 1988-12-21 | 1988-12-21 | Nuclear fuel assembly |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02167496A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102272857A (en) * | 2008-11-12 | 2011-12-07 | 阿海珐核能公司 | Lower nozzle for nuclear fuel assembly for pressurized water reactor |
-
1988
- 1988-12-21 JP JP63320692A patent/JPH02167496A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102272857A (en) * | 2008-11-12 | 2011-12-07 | 阿海珐核能公司 | Lower nozzle for nuclear fuel assembly for pressurized water reactor |
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