JPS62276490A - Fuel rod for nuclear reactor - Google Patents
Fuel rod for nuclear reactorInfo
- Publication number
- JPS62276490A JPS62276490A JP61119067A JP11906786A JPS62276490A JP S62276490 A JPS62276490 A JP S62276490A JP 61119067 A JP61119067 A JP 61119067A JP 11906786 A JP11906786 A JP 11906786A JP S62276490 A JPS62276490 A JP S62276490A
- Authority
- JP
- Japan
- Prior art keywords
- region
- fuel
- nuclear
- enrichment
- 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.)
- Pending
Links
- 239000000446 fuel Substances 0.000 title claims description 78
- 239000003758 nuclear fuel Substances 0.000 claims description 66
- 239000000463 material Substances 0.000 claims description 60
- 238000005253 cladding Methods 0.000 claims description 4
- 238000009826 distribution Methods 0.000 description 21
- 239000008188 pellet Substances 0.000 description 8
- 238000000034 method Methods 0.000 description 5
- 230000009257 reactivity Effects 0.000 description 5
- 239000011800 void material Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052770 Uranium Inorganic materials 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 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
- Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
Abstract
(57)【要約】本公報は電子出願前の出願データであるた
め要約のデータは記録されません。(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.
Description
【発明の詳細な説明】
３、発明の詳細な説明
〔発明の目的〕
（産業上の利用分野）
本発明は原子炉用燃料棒に係り、特に燃料経済性の優れ
た原子炉用燃料棒に関する。Detailed Description of the Invention 3. Detailed Description of the Invention [Object of the Invention] (Field of Industrial Application) The present invention relates to a fuel rod for a nuclear reactor, and in particular to a fuel rod for a nuclear reactor with excellent fuel economy. .
（従来の技術）
現在の軽水炉に用いられる燃料は薄肉の燃料被覆管内に
ベレット状に成形した核燃料物質を多数側装填してその
両端を端栓で茫封して燃料棒とし、その燃料棒を燃料チ
ャンネル内に多数本束ねて収容した燃料集合体として使
用している。従来の原子炉用燃料棒に装填される核燃料
物質は軸方向において同一の濃縮度を有するものが一般
に採用されていた。しかし、原子炉内の軸方向における
核燃料の燃え方は、不均一であるため、核燃料物質は一
様に消耗しない。その結果、運転サイクル末期に至り、
燃料棒交換の時点においても、高価な核燃料物質が部分
的に残存し、不経済であった。(Prior art) The fuel used in current light water reactors is made by loading a large number of pellet-shaped nuclear fuel materials into a thin fuel cladding tube and sealing both ends with end plugs to form a fuel rod. It is used as a fuel assembly in which a large number of fuel rods are bundled and housed in a fuel channel. Nuclear fuel materials loaded into fuel rods for conventional nuclear reactors generally have the same enrichment in the axial direction. However, since nuclear fuel burns unevenly in the axial direction within a nuclear reactor, the nuclear fuel material is not consumed uniformly. As a result, at the end of the driving cycle,
Even at the time of fuel rod replacement, some expensive nuclear fuel material remained, making it uneconomical.
特に、沸騰水型原子炉（以下ＢＷＲと称す）では原子炉
の炉心部で減速材の気泡である蒸気ボイドが発生する。In particular, in a boiling water reactor (hereinafter referred to as BWR), steam voids, which are moderator bubbles, occur in the core of the reactor.
ボイド発生率分布は、炉心上部はど大きく、炉心出口に
おけるボイド率は７０％前後の値となる。従って炉心上
部の反応度が低く、一方炉心下部の反応度が高くなって
炉心下部に大きな出力ピークが出現する。安全上、この
出力ピークを回避するためにＢＷＲでは上記ボイド発生
率分布の影響を相殺するように炉心底部より制御棒を挿
入して炉心下部の反応度を下げ出力ピークを調整してい
る。そのために制御棒を緻密な操作計画に従って操作し
なければならず、煩雑な作業が必要とされていた。The void generation rate distribution is the highest in the upper part of the core, and the void rate at the core exit is around 70%. Therefore, the reactivity in the upper part of the core is low, while the reactivity in the lower part of the core is high, and a large power peak appears in the lower part of the core. For safety reasons, in order to avoid this output peak, in BWRs, control rods are inserted from the bottom of the reactor core to offset the influence of the void generation rate distribution, thereby lowering the reactivity in the lower part of the core and adjusting the output peak. For this purpose, the control rods had to be operated according to a detailed operation plan, which required complicated work.
一方、制御棒の操作のみに頼らず、燃料棒自体に自己制
御性を持たせる試みもある。すなわち、燃料棒に装填さ
れる核燃料物質の濃縮度を軸の上下方向で変化させるこ
とにより、軸方向の出力分布を調整する方式も試行され
ている。具体的には、燃料集合体を構成する燃料棒の下
部に装填する核燃料ベレットの濃縮度を上部より低（設
定して反応度を相対的に抑制する方式である。また他の
方式として、燃料棒の軸方向の中心部に濃縮度の高い核
燃料ベレットを装填し中心部から上下方向に濃縮度が漸
減するように核燃料ベレットを配置する対策も採用され
ていた。On the other hand, there are also attempts to provide self-control to the fuel rods themselves, rather than relying solely on the operation of control rods. That is, a method of adjusting the power distribution in the axial direction by changing the enrichment of the nuclear fuel material loaded into the fuel rod in the vertical direction of the shaft has also been attempted. Specifically, this method relatively suppresses the reactivity by setting the enrichment of the nuclear fuel pellets loaded in the lower part of the fuel rods that make up the fuel assembly to be lower than the upper part. A measure was also adopted in which highly enriched nuclear fuel pellets were loaded in the axial center of the rod, and the nuclear fuel pellets were arranged so that the enrichment level gradually decreased in the vertical direction from the center.
（発明が解決しようとする問題点）
しかしいずれの方式においても高い濃縮度を有する核燃
料ベレットを装填した部位において、線出力密度の高い
ピークが出現し、この出力ピークは原子炉安全上また、
燃料棒自体の健全性の維持の観点から好ましくない。ま
た燃料棒の軸方向全長にわたり、核燃料物質の消耗割合
が一様でなく、運転サイクル末期において部分的に核燃
料物質が残存する例が多く、その状態で燃料棒を交換す
ることは、極めて不経済であった。(Problems to be Solved by the Invention) However, in either method, a high peak of linear power density appears at the location where nuclear fuel pellets with a high enrichment degree are loaded, and this power peak is important for reactor safety and
This is unfavorable from the viewpoint of maintaining the integrity of the fuel rod itself. Additionally, the consumption rate of nuclear fuel material is not uniform over the entire axial length of the fuel rod, and there are many cases where nuclear fuel material remains partially at the end of the operating cycle, making it extremely uneconomical to replace the fuel rod in this state. Met.
また反応度を調整するために制御棒を操作することは一
般に炉内局所に大きな出力変化を伴い、燃料棒自体の健
全性を維持する観点からも好ましくない。さらに制御棒
を緻密に操作する作業は煩雑であり、原子炉の運転管理
上問題であった。Furthermore, manipulating the control rods to adjust the reactivity generally involves a large change in power locally within the reactor, which is undesirable from the viewpoint of maintaining the integrity of the fuel rods themselves. Furthermore, the work of precisely manipulating the control rods was complicated and posed a problem in the operational management of the reactor.
本発明は上記の問題点を解決するために発案されたもの
であり、運転サイクル末期において燃料棒の軸方向にお
ける核燃料物質の残存割合が一様に低い状態になるよう
に、予め、燃料棒を細かく区分けしてその各領域に装填
する核燃料物質の濃縮度を最適に分布させることによっ
て最小量の核燃料物質から最大限の熱エネルギーを取り
出せる経済的な原子炉用燃料棒を提供るすことを目的と
する。The present invention was devised to solve the above-mentioned problems, and the present invention is designed to prepare fuel rods in advance so that the remaining ratio of nuclear fuel material in the axial direction of the fuel rods is uniformly low at the end of the operating cycle. The purpose is to provide an economical fuel rod for a nuclear reactor that can extract the maximum thermal energy from the minimum amount of nuclear fuel material by dividing the nuclear fuel material into small sections and optimally distributing the enrichment of the nuclear fuel material loaded into each region. shall be.
（発明の構成）
（問題点を解決するための手段）
上記目的を達成するために本発明の原子炉用燃料棒は、
燃料棒有効長の上端から下端までを軸方向に順に領域工
ないし領域Ｖの５つの領域に区画し、前記領域工、領域
■及び領域Ｖに装填する核燃料物質の濃縮度を、領域■
及び領域■に装填する核燃料物質の濃縮度より低く設定
し、かつ領域ＩＩおよび領域■にＶ：を填した核燃料物
質の含有量の炉全体における総和が、原子炉の運転期間
申合々の領域において独立して臨界を維持できる最小臨
界量以上に調整されて構成される。(Structure of the invention) (Means for solving the problems) In order to achieve the above object, the fuel rod for a nuclear reactor of the present invention has the following features:
The effective length of the fuel rod is divided into five regions in the axial direction from the upper end to the lower end, and the enrichment of the nuclear fuel material to be loaded in the region construction, region
The total content of nuclear fuel material in the entire reactor, which is set lower than the enrichment of the nuclear fuel material to be loaded in region II and region II, and V: in region II and region II, is the region that matches the operating period of the reactor. It is configured such that the amount is adjusted to be greater than the minimum critical amount that can independently maintain criticality.
（作用）
上記構成によれば、燃料棒の中央部分の領域■に低濃縮
度の核燃料物質を装填し、この領域■を境界として上下
に高濃縮度の核燃料物質を装填した領域■と領域■を配
置したことにより、実質的に炉心の高度燃焼範囲を上下
の２領域に分割したので軸方向のピーク出力の分散が図
れる。一方、臨界達成に関与しないＷ４域■の核燃料物
質の濃縮度は低減できる。従って領域■へ投入する核燃
料物質の節減が可能となる。(Function) According to the above configuration, low-enrichment nuclear fuel material is loaded into the region (■) in the center of the fuel rod, and with this region (■) as a boundary, the upper and lower regions are the regions (■) and (2) where high-enrichment nuclear fuel material is loaded. By arranging this, the high combustion range of the core is essentially divided into two regions, upper and lower, so that the peak output in the axial direction can be distributed. On the other hand, the enrichment of nuclear fuel material in the W4 region (3), which is not involved in achieving criticality, can be reduced. Therefore, it is possible to reduce the amount of nuclear fuel material input into area (3).
また領域■及び領域■の核燃料物質の含有ｉの炉全体に
おける総和が原子炉の運転サイクル末期においても独立
して臨界を維持できるように最小臨界耐以上に調整され
ているので、それぞれの領域は運転サイクル末期まで比
較的低い出力ピークを有する定常的な出力分布を維持す
ることができる。In addition, since the sum total of the content i of nuclear fuel material in regions (2) and (2) in the entire reactor is adjusted to be greater than the minimum criticality resistance so that criticality can be maintained independently even at the end of the reactor operating cycle, each region is A steady power distribution with relatively low power peaks can be maintained until the end of the operating cycle.
さらに、燃料棒の上下端すなわち領域工及び領域Ｖに低
濃縮度の核燃料物質が装填されているので、燃料棒の上
下端からの中性子の漏れが抑制される。従って燃料棒全
体としては装填する核燃料物質が少ないにも拘らず容易
に臨界状態に達することができる。Furthermore, since the upper and lower ends of the fuel rods, that is, the region V and the region V, are loaded with low enrichment nuclear fuel material, leakage of neutrons from the upper and lower ends of the fuel rods is suppressed. Therefore, the fuel rod as a whole can easily reach a critical state even though the amount of nuclear fuel material loaded therein is small.
このように高度燃焼領域を分散し、その上下領域に低濃
縮度の核燃料物質を配しており、この部分において核燃
料物質を節減することができる。In this way, the high combustion region is dispersed, and low enrichment nuclear fuel material is placed in the upper and lower regions, making it possible to save nuclear fuel material in this region.
（実施例）
以下、本発明に係る原子炉用燃料棒の一実施例について
添付図面に基いて説明する。(Example) Hereinafter, an example of the fuel rod for a nuclear reactor according to the present invention will be described based on the accompanying drawings.
第１図において燃料棒１は、一般にベレット状に成形加
工した核燃料物質２を薄肉の合金製燃料被覆管３に直列
に多数装填しその両端を端栓４で溶接することにより内
部が密封される。なお燃料棒１の上部空間には、核燃料
物質２が軸方向に移動することを防止するスプリング５
が内装される。In FIG. 1, a fuel rod 1 is constructed by loading a large number of nuclear fuel materials 2 formed into pellets in series into a thin-walled alloy fuel cladding tube 3 and welding both ends of the tube with end plugs 4 to seal the inside. . Note that a spring 5 is installed in the upper space of the fuel rod 1 to prevent the nuclear fuel material 2 from moving in the axial direction.
will be decorated.
この燃料棒１は多数本が束ねられて燃料チャンネル内に
収容され燃料集合体が形成される。そして多数の燃料集
合体が原子炉の炉心に縦方向に装荷される。燃料棒１は
ベレット状の核燃料物質が装填された部分の良さが燃料
棒有効良しであり、一般に３．７ｍのものが標準として
採用されている。A large number of fuel rods 1 are bundled and housed in a fuel channel to form a fuel assembly. A large number of fuel assemblies are then loaded vertically into the core of the nuclear reactor. The fuel rod 1 has a portion loaded with pellet-shaped nuclear fuel material that is effective, and a length of 3.7 m is generally adopted as a standard.
本発明の燃料棒においては、燃料棒有効長を軸方向に領
域Ｉから領域Ｖまでの５領域に区画し、そのうち、領域
工、領域■及び領域Ｖに装填する核燃料物質の濃縮度を
、領域■及び領域ＩＶに装填する核燃料物質の濃縮度よ
り低く設定している。In the fuel rod of the present invention, the effective length of the fuel rod is divided into five regions from region I to region V in the axial direction. The enrichment level is set lower than the enrichment level of the nuclear fuel material loaded in (2) and Area IV.
また、領域■及び領域ＩＶに装填された核燃料物質の含
有量の、炉全体における総和は、原子炉運転期間申合々
の領域において独立して臨界を維持できる最小臨界ｍ以
上に調整されている。In addition, the total content of the nuclear fuel material loaded in region (IV) and region (IV) in the entire reactor is adjusted to be equal to or higher than the minimum criticality m that can independently maintain criticality in the appropriate region for the reactor operating period. .
次に本発明の燃料棒の各領域の長さ、及び装填する核燃
料物質の濃縮度を変えて、出力試験を実施した結果を第
２図ないし第４図に示す。ここでは、通常の運転サイク
ルである一定期間すなわち定期点検における燃料交換の
頻度を考慮して、期間を１年に設定し、その間原子炉か
ら定常的な総出力を得るのに必要な、核燃料物質の軸方
向の濃縮度分布を各領域長さと共に種々設定して試験を
行った。そして、燃料棒全体における平均濃縮度Ｃ０を
最小にする濃縮度分布及び領域長さの組合ぜを最適化手
法による数値計算により求めた。すなわち原子炉の総出
力は出力分布の積分値を一定にしながら出力分布を変化
させ、装填する核燃料物質の平均濃縮度Ｃ７が最小にな
る組合せを決定し実証した。Next, FIGS. 2 to 4 show the results of power tests carried out by changing the length of each region of the fuel rod of the present invention and the enrichment level of the loaded nuclear fuel material. Here, the period is set to one year, taking into consideration the frequency of fuel exchange during periodic inspections, which is a certain period of the normal operating cycle, and the nuclear fuel material required to obtain a steady total output from the reactor during that period is set as one year. Tests were conducted by setting various axial enrichment distributions and lengths of each region. Then, a combination of enrichment distribution and region length that minimizes the average enrichment C0 over the entire fuel rod was determined by numerical calculation using an optimization method. That is, for the total output of the reactor, the power distribution was varied while keeping the integral value of the power distribution constant, and the combination that minimized the average enrichment C7 of the nuclear fuel material to be loaded was determined and verified.
第２図は本発明の燃料棒を多数集合させて燃料集合体と
してＢＷＲに装荷して運転時の相対出力分布を調査した
結果を示す。炉心高さＨは燃料棒有効長しに対応する。FIG. 2 shows the results of investigating the relative power distribution during operation by assembling a large number of fuel rods of the present invention and loading them into a BWR as a fuel assembly. The core height H corresponds to the effective length of the fuel rods.
本実施例において、各領域の長さは燃料棒有効長りに対
して下記の通りである。In this embodiment, the length of each region is as follows with respect to the effective length of the fuel rod.
領域■の長さ・・・・・・・・・□Ｌ
領域■の長さ・・・・・・・・・□Ｌ
領域Ｖの長ざ・・・・・・・・・ Ｌまた、各領
域内に装填した核燃料物質の濃縮度は、濃縮分布ｔａＡ
２に示すように、領域■及び領域■に段階的に高濃縮度
の燃料ベレットを配し、領域工、ＩＩＩ、Ｖには天然ウ
ランの燃料ベレットを装填している。その結果、核燃料
物質の平均濃縮度Ｃは１．８７％となった。運転期間中
におけ■
る出力状況は出力分布曲線Ｂ２の結果が得られ、期間を
通してほぼ一定の値となった。なお、本実施例では、軸
方向の出力ピーク値は２．４となっている。Length of area ■・・・・・・・・・□L Length of area ■・・・・・・・・・□L Length of area V・・・・・・・・・L Also, each The enrichment level of the nuclear fuel material loaded in the area is defined by the enrichment distribution taA
As shown in Figure 2, highly enriched fuel pellets are arranged in stages in Regions (2) and (2), and natural uranium fuel pellets are loaded in Regions III and V. As a result, the average enrichment C of nuclear fuel material was 1.87%. The output status during the operation period was as shown by the output distribution curve B2, which was a nearly constant value throughout the period. In this example, the output peak value in the axial direction is 2.4.
この原子炉において同一出力を与える従来形式の燃料棒
、すなわち軸方向全域に均一な濃縮度を有する核燃料物
質を装填した燃料棒の平均濃縮度は２．０６％であるか
ら第２図の実施例の燃料棒の構成によれば９．２％の核
燃料物質が節減される。In this nuclear reactor, the average enrichment of conventional fuel rods that give the same output, that is, fuel rods loaded with nuclear fuel material that has a uniform enrichment throughout the axial direction, is 2.06%, so the embodiment shown in Figure 2 This fuel rod configuration saves 9.2% of nuclear fuel material.
第３図は他の実施例による運転結果を示す。FIG. 3 shows the results of operation according to another embodiment.
この場合は燃料棒の出力ピーク値を第２図の場合より抑
制するために、領ｔ＋ｉｌＫ、■における核燃料物質の
濃縮度を若干下げるとともに領域長さを拡大した。すな
わち相対出力ピーク値を１．４以下という条件のもとに
、核燃料物質の平均濃縮度を最小にする濃縮度分布線Ａ
３と出力分布曲線Ｂ３を同様に数値計算等で求めた。In this case, in order to suppress the output peak value of the fuel rods more than in the case of FIG. 2, the enrichment of the nuclear fuel material in the region t+ilK, (2) was slightly lowered and the region length was expanded. In other words, the enrichment distribution line A that minimizes the average enrichment of nuclear fuel material under the condition that the relative output peak value is 1.4 or less
3 and the output distribution curve B3 were similarly obtained by numerical calculation etc.
この実施例における各領域の長さ等の条件は下記の通り
である。Conditions such as the length of each region in this example are as follows.
また装填する核燃料物質の平均濃縮度Ｃ４は１．９３％
である。The average enrichment C4 of the nuclear fuel material to be loaded is 1.93%.
It is.
従って本実施例の燃料棒によれば従来のものと比較して
約６．３％の核燃料物質が節減できる。Therefore, the fuel rod of this embodiment can save about 6.3% of nuclear fuel material compared to the conventional one.
第４図は以上の伯の実施例による運転結果を示す。FIG. 4 shows the results of operation according to the above embodiment.
この場合は第３図と同様に軸方向の相対出力ピーク値を
１．４以下に設定し、かつ核燃料物質の濃縮度を２ＦＪ
類に限定して構成し、濃縮度分布線Ａ と対応する相対
出力分布曲線Ｂ４を得た。In this case, as in Figure 3, the relative output peak value in the axial direction is set to 1.4 or less, and the enrichment of the nuclear fuel material is set to 2FJ.
A relative output distribution curve B4 corresponding to the enrichment distribution line A was obtained.
この実施例における、各領域の長さは、下記の通りであ
る。In this example, the length of each region is as follows.
また装填する核燃料物質の平均濃縮度Ｃ，は２．００％
でる。The average enrichment C of the nuclear fuel material to be loaded is 2.00%.
Out.
従って本実施例によれば従来の燃料棒と比較して約２．
９％の核燃料物質が節減できる。Therefore, according to this embodiment, compared to the conventional fuel rod, it is approximately 2.
9% nuclear fuel material can be saved.
第２図、第３図及び第４図に示す実施例ではいずれにお
いても燃料棒の中心部から上下に高濃縮度の燃料ベレッ
トを装填した領域ＩＩ、■を配置し、炉全体としてそれ
ぞれの領域においてｍ界状態を達成しまた維持できるよ
うに核燃料物質の含有量が調整されているので、その２
領域の中間にあり、臨界の達成維持に対して関係の少な
い領域■の核燃料物質の含有１を低減できる。In the embodiments shown in FIGS. 2, 3, and 4, regions II and (2) loaded with highly enriched fuel pellets are arranged above and below the center of the fuel rod, and each region is divided into two regions as a whole. Since the content of nuclear fuel material is adjusted so that the m-world state can be achieved and maintained in Part 2,
It is possible to reduce the nuclear fuel material content 1 in region (2), which is located in the middle of the region and is less relevant to achieving and maintaining criticality.
なお、この燃料棒の有効長は現在約３．７ｍのものが標
準化されて採用されている。この長さは炉全体における
臨界維持のために必要な長さの２倍以上に達しているの
で、本発明の燃料棒のように臨界領域を軸方向の２領域
に設定できる。Note that the effective length of this fuel rod is currently standardized and adopted as approximately 3.7 m. Since this length is more than twice the length required to maintain criticality in the entire reactor, the critical region can be set in two regions in the axial direction as in the fuel rod of the present invention.
第３図の実施例においては、燃料棒の軸方向出力ビーク
値を制限値（１，４）以下に抑えるために領域ＩＩ、Ｉ
Ｖに装填する核燃料物質の濃縮度を低くしており、それ
による出力不足分を補償するために領域長さが拡大する
。一方、低濃縮度の核燃料物質を装填する領域工、ＩＩ
Ｉ、■の長さは、第２図の実施例の場合を最大として、
出力ピークの制限値が小さくなるのに対応して縮小化す
る。従ってｖｔ填する核燃料物質の平均濃縮度は上昇す
るので核燃料物質の節減効果は小さくなる。In the embodiment shown in FIG. 3, in order to suppress the axial power peak value of the fuel rod to below the limit value (1, 4), regions II, I
The enrichment of the nuclear fuel material loaded into the V is lowered, and the region length is expanded to compensate for the resulting lack of output. On the other hand, area engineering for loading low-enrichment nuclear fuel material, II
The lengths of I and ■ are maximum in the case of the embodiment shown in FIG.
The output peak is reduced in size as the limit value of the output peak becomes smaller. Therefore, the average enrichment of the nuclear fuel material to be loaded into the VT increases, and the effect of saving nuclear fuel material becomes smaller.
近年、原子炉の運転にあたり、安全性及び燃料棒自体の
叶全性維持の見地から燃料棒の線出力密度を可及的に低
く平坦化する方向で改良が進められており、線出力密度
の制限値に対応した最適な核燃料物質の濃縮度分布及び
装填する領域長さが上記手法により適宜決定できる。In recent years, when operating nuclear reactors, improvements have been made in the direction of flattening the linear power density of fuel rods as low as possible from the standpoint of safety and maintaining the integrity of the fuel rods themselves. The optimum enrichment distribution of nuclear fuel material corresponding to the limit value and the length of the loading region can be appropriately determined by the above method.
以上はＥ３ＷＲの場合について説明したが、本発明の阜
本的思想は加圧水型原子炉（ＰＷＲ）の場合にも適用で
きることは明らかである。ただし、ＰＷＲでは冷却材が
加圧されているため燃料棒におけるボイド分布は発生し
ないので、核燃料物質の濃縮度分布は軸方向の上下で対
称形となることは言うまでもない。Although the case of E3WR has been described above, it is clear that the original idea of the present invention can also be applied to the case of pressurized water reactor (PWR). However, in PWR, since the coolant is pressurized, no void distribution occurs in the fuel rods, so it goes without saying that the enrichment distribution of the nuclear fuel material is symmetrical in the upper and lower axial directions.
（発明の効果）
以上の説明で明らかなように本発明の原子炉用燃料棒に
よれば、軸方向の中心部に低濃縮度域を設けその上下に
高濃縮度域を配し炉全体としてその２領域において独自
に臨界を達成できるように核燃料物質量を調整している
ため、出力ピークを２領域に分散でき、小ざく抑えるこ
とが可能となる。従って、線出力密度及び核燃料の消耗
速度も平均化し、燃料交換時における残存燃料の割合が
少い。一方、臨界達成に対する寄与の少ない中心部の核
燃料物質の濃縮度を低減することができる。従って高価
な核燃料物質を節減した経済的な原子炉の運転が可能と
なる。(Effects of the Invention) As is clear from the above explanation, according to the fuel rod for a nuclear reactor of the present invention, a low enrichment region is provided at the center in the axial direction, and high enrichment regions are arranged above and below the low enrichment region, and the entire reactor Since the amount of nuclear fuel material is adjusted so that criticality can be achieved independently in these two regions, the output peak can be dispersed into the two regions and can be kept small. Therefore, the linear power density and nuclear fuel consumption rate are also averaged, and the proportion of remaining fuel at the time of refueling is small. On the other hand, it is possible to reduce the enrichment of the nuclear fuel material in the core, which makes little contribution to achieving criticality. Therefore, it becomes possible to operate the nuclear reactor economically while saving expensive nuclear fuel materials.
また燃料棒の各領域で核燃料物質の濃縮度を変えており
、燃料棒自体が軸方向の出力分布を制御する自己１１Ｊ
ＩＩ性をもつので、制御棒に対する依存度を少な（し
、出力調整作業が簡易化する。また制御棒を操作して炉
の出力を変化させる場合に比べ局所的に大きな出力変化
を伴わないので燃料棒自体の健全性を維持するためにも
有効である。In addition, the enrichment of nuclear fuel material is varied in each region of the fuel rod, and the fuel rod itself controls the axial power distribution.
This reduces the dependence on the control rods (and simplifies the output adjustment work. Also, compared to changing the reactor output by operating the control rods, it does not involve large local output changes. It is also effective for maintaining the integrity of the fuel rod itself.
第１図は本発明の原子炉用燃料棒を一部破断して示す正
面図、第２図ないし第４図は燃料棒における各領域長さ
及び装填する核燃料物質の濃縮度を種々変化させた場合
の原子炉の出力分布を表す特性図である。
１・・・燃料棒、２・・・核燃料物質、３・・・合金被
覆管、４・・・端栓、５・・・スプリング、Ｈ・・・炉
心高さ、し・・・燃料棒有効長、Ｃ１，ｌ・・・平均濃
縮度、Ｉ、ＩＩ。
ｍ、ｒｖ、ｖ−・・領域、Ａ、Ａ３．Ａ４・・・軸方向
部縮度分布線、Ｂ２，８３．Ｂ４・・・軸方向出力分布
曲線。Figure 1 is a partially cutaway front view of a fuel rod for a nuclear reactor according to the present invention, and Figures 2 to 4 show fuel rods in which the length of each region and the enrichment of the nuclear fuel material to be loaded are varied. FIG. 1... Fuel rod, 2... Nuclear fuel material, 3... Alloy cladding tube, 4... End plug, 5... Spring, H... Core height, C... Fuel rod effective length, C1,l...average enrichment, I, II. m, rv, v--area, A, A3. A4... Axial shrinkage distribution line, B2,83. B4... Axial output distribution curve.
Claims (1)
において、燃料棒有効長の上端から下端までを軸方向に
順に領域 I ないし領域Ｖの５つの領域に区画し、前記
領域 I 、領域III及び領域Ｖに装填する核燃料物質の濃
縮度を、領域II及び領域IVに装填する核燃料物質の濃縮
度より低く設定し、かつ領域IIおよび領域IVに装填した
核燃料物質の含有量の炉全体における総和が、原子炉の
運転期間中各々の領域において独立して臨界を維持でき
る最小臨界量以上に調整されたことを特徴とする原子炉
用燃料棒。 ２、領域 I 、領域II、領域III、領域IV及び領域Ｖの長
さが、それぞれ燃料棒有効長の２４分の４以下、２４分
の５以上、２４分の７以下、２４分の６以上及び２４分
の２以下に設定された特許請求の範囲第１項記載の原子
炉用燃料棒。[Claims] 1. In a fuel rod for a nuclear reactor in which a fuel cladding tube is filled with nuclear fuel material, the effective length of the fuel rod is divided into five regions from the upper end to the lower end in the axial direction, region I to region V. , the enrichment of the nuclear fuel material loaded in Region I, Region III and Region V is set lower than the enrichment of the nuclear fuel material loaded in Region II and Region IV, and the enrichment of the nuclear fuel material loaded in Region II and Region IV is 1. A fuel rod for a nuclear reactor, characterized in that the total content in the entire reactor is adjusted to be equal to or higher than the minimum critical amount that can maintain criticality independently in each region during the operating period of the nuclear reactor. 2. The lengths of Region I, Region II, Region III, Region IV, and Region V are 4/24 or less, 5/24 or more, 7/24 or less, and 6/24 or more of the effective length of the fuel rod, respectively. and a fuel rod for a nuclear reactor according to claim 1, which is set to 2/24 or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61119067A JPS62276490A (en) | 1986-05-26 | 1986-05-26 | Fuel rod for nuclear reactor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61119067A JPS62276490A (en) | 1986-05-26 | 1986-05-26 | Fuel rod for nuclear reactor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS62276490A true JPS62276490A (en) | 1987-12-01 |
Family
ID=14752074
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61119067A Pending JPS62276490A (en) | 1986-05-26 | 1986-05-26 | Fuel rod for nuclear reactor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62276490A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20180044320A (en) * | 2015-08-27 | 2018-05-02 | 테라파워, 엘엘씨 | Fuel element with multi-smear density fuel |
-
1986
- 1986-05-26 JP JP61119067A patent/JPS62276490A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20180044320A (en) * | 2015-08-27 | 2018-05-02 | 테라파워, 엘엘씨 | Fuel element with multi-smear density fuel |
| JP2018529095A (en) * | 2015-08-27 | 2018-10-04 | テラパワー， エルエルシー | Fuel element having multiple smear density fuels |
| JP2021119358A (en) * | 2015-08-27 | 2021-08-12 | テラパワー， エルエルシー | Device including fuel element for fuel assembly |
| KR20230038603A (en) * | 2015-08-27 | 2023-03-20 | 테라파워, 엘엘씨 | Fuel element with multi-smear density fuel |
| US11990249B2 (en) | 2015-08-27 | 2024-05-21 | Terrapower, Llc | Fuel element with multi-smear density fuel |
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