JPH05215881A - Nuclear reactor - Google Patents
Nuclear reactorInfo
- Publication number
- JPH05215881A JPH05215881A JP4022233A JP2223392A JPH05215881A JP H05215881 A JPH05215881 A JP H05215881A JP 4022233 A JP4022233 A JP 4022233A JP 2223392 A JP2223392 A JP 2223392A JP H05215881 A JPH05215881 A JP H05215881A
- Authority
- JP
- Japan
- Prior art keywords
- control rod
- fuel
- reactor
- fuel assembly
- reactivity
- 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
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]
【産業上の利用分野】本発明は原子炉に係わり、特に下
部挿入による制御棒を有する原子炉に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear reactor, and more particularly to a nuclear reactor having a control rod with a bottom insertion.
【０００２】[0002]
【従来の技術】一般に、沸騰水型原子炉では余剰反応を
制御するための１つの方法として制御棒が使用されてお
り、この制御棒は図６の横断面図で示すように、制御棒
１は多数のＢ4 Ｃ（ホウ素化合物）の棒２を十文字に配
列して構成されていて、燃料棒３を多数本配列した燃料
バンドルをチャンネルボックス４で包囲して構成された
燃料集合体５の４体に１体の割合で燃料集合体５相互間
に配設されている。これは、電気出力 135kWの原子炉を
例に挙げると、図７の全炉心の第２象限配置図にあるよ
うに、燃料集合体５の 872体に対し、制御棒１が 205本
使用されている。2. Description of the Related Art Generally, in a boiling water reactor, control rods are used as one method for controlling the excess reaction. As shown in the cross sectional view of FIG. Is composed of a large number of B 2 C (boron compound) rods 2 arranged in a cross shape, and a fuel bundle 5 composed of a channel box 4 surrounding a fuel bundle in which a large number of fuel rods 3 are arranged. The fuel assemblies 5 are arranged at a ratio of one in four. Taking a nuclear reactor with an electric output of 135 kW as an example, 205 control rods 1 are used for 872 fuel assemblies 5 as shown in the second quadrant layout of the whole core in FIG. There is.
【０００３】制御棒１の操作については、原子炉の運転
停止時には、全制御棒１が全ストロークで炉心内に挿入
されて、原子炉が未臨界となるように制御される。また
運転時には、制御棒１の一部を引き抜いて臨界となるよ
うに制御棒１の本数、並びに挿入深度が調整される。図
８は制御棒の斜視図で、制御棒１は通常、上端部にハン
ドル６と中央部に中性子吸収材であるＢ4 Ｃの棒２、さ
らに下部には下部スカート７を配した構成となってい
る。With respect to the operation of the control rods 1, when the reactor is not in operation, all the control rods 1 are inserted into the core with all strokes so that the reactor is controlled to be subcritical. Further, during operation, the number of control rods 1 and the insertion depth are adjusted so that a part of the control rods 1 is pulled out to become critical. FIG. 8 is a perspective view of a control rod. The control rod 1 usually has a handle 6 at the upper end, a B 2 C rod 2 as a neutron absorber at the center, and a lower skirt 7 at the lower part. ing.
【０００４】この図８では中性子吸収材としてＢ4 Ｃを
使用した例を示しているが、Ｈｆ（ハフニウム）等を使
用したものもある。従来、制御棒１内で中性子吸収材が
配設されている制御棒有効長（有効部の長さ）８は、図
９の燃料と制御棒の有効長構成図に示すように、燃料集
合体５の燃料有効長（燃料の長さ）９とほぼ同じか、や
や短く設計されている。また沸騰水型原子炉は図10の縦
断面図に示すように、原子炉圧力容器10内で炉心11を支
えている炉心支持板12の下に下部プレナム13と呼ばれる
領域があり、図示しない再循環ポンプから吐出された冷
却材が下部プレナム13内を上方に向かって流れる。Although FIG. 8 shows an example in which B 4 C is used as the neutron absorbing material, there is one using Hf (hafnium) or the like. Conventionally, the control rod effective length (the length of the effective portion) 8 in which the neutron absorbing material is arranged in the control rod 1 is as shown in the fuel and control rod effective length configuration diagram of FIG. It is designed to be almost the same as the effective fuel length (fuel length) 9 of 5 or slightly shorter. Further, the boiling water reactor has a region called a lower plenum 13 below the core support plate 12 supporting the core 11 in the reactor pressure vessel 10 as shown in the vertical sectional view of FIG. The coolant discharged from the circulation pump flows upward in the lower plenum 13.
【０００５】この下部プレナム13には制御棒案内管14が
配置されており、制御棒１は引抜き時に、この制御棒案
内管14に収納される。また制御棒案内管14は、制御棒駆
動機構ハウジング15を通して原子炉圧力容器10外の制御
棒駆動機構16につながっていて、炉心11内への制御棒１
の挿入、引抜きは、この制御棒駆動機構16によって操作
される。なお、前記制御棒案内管14、および制御棒駆動
機構ハウジング15の長さは、一般に制御棒１のストロー
ク長とほぼ同じとなっている。A control rod guide tube 14 is arranged in the lower plenum 13, and the control rod 1 is housed in the control rod guide tube 14 when it is pulled out. Further, the control rod guide tube 14 is connected to a control rod drive mechanism 16 outside the reactor pressure vessel 10 through a control rod drive mechanism housing 15 to control the control rod 1 into the reactor core 11.
The control rod drive mechanism 16 operates the insertion and extraction of the. The lengths of the control rod guide tube 14 and the control rod drive mechanism housing 15 are generally almost the same as the stroke length of the control rod 1.
【０００６】[0006]
【発明が解決しようとする課題】炉心11において制御棒
１を短尺化することは、制御棒１自体のコストダウンが
計れるほか、制御棒１に付随する制御棒案内管14、およ
び制御棒駆動機構ハウジング15等も短尺化できるので、
下部プレナム13の長さも短縮されて、原子力圧力容器10
をコンパクトにすることができ、さらなるコストダウン
ができる。同時に制御棒駆動機構ハウジング15、および
原子炉圧力容器10の短尺化により、原子炉圧力容器10を
収容した図示しない原子炉格納容器の下端を従来と同じ
高さに設定した場合に、相対的に従来より炉心位置が原
子炉圧力容器下方にシフトするため、重心位置が下がり
耐震性が向上する。The reduction of the length of the control rod 1 in the core 11 can reduce the cost of the control rod 1 itself, and the control rod guide tube 14 attached to the control rod 1 and the control rod drive mechanism. Since the housing 15 etc. can be shortened,
The length of the lower plenum 13 is also shortened, and the nuclear pressure vessel 10
Can be made compact and the cost can be further reduced. At the same time, when the control rod drive mechanism housing 15 and the reactor pressure vessel 10 are shortened, when the lower end of the reactor containment vessel (not shown) accommodating the reactor pressure vessel 10 is set to the same height as the conventional one, it is relatively Since the core position shifts below the reactor pressure vessel, the center of gravity position is lowered and seismic resistance is improved.
【０００７】また、制御棒１は炉心11内において中性子
吸収により制御棒価値が減少し、通常その価値が約10％
減少すると定期点検時に新しい制御棒１に交換される。
従って、制御棒１の短尺化は放射性廃棄物の削減にも貢
献することから、制御棒１における合理的な短尺化が要
望されていた。しかしながら、核反応の面からは単に制
御棒１を短尺化すれば、その分だけ制御棒価値が減少
し、例えば炉停止余裕に不足が生じることになる。また
原子炉の停止時には全ての制御棒１が炉心11内に挿入さ
れて、原子炉は未臨界の状態にあるが、この炉停止状態
において、いずれかの１本の制御棒１が炉心11から引抜
かれても原子炉が未臨界であることが要求されている。Further, the control rod 1 has a reduced control rod value due to neutron absorption in the core 11, and its value is usually about 10%.
If it decreases, it will be replaced with a new control rod 1 at the time of regular inspection.
Therefore, the shortening of the control rod 1 also contributes to the reduction of radioactive waste, and therefore, the rational shortening of the control rod 1 has been demanded. However, from the viewpoint of nuclear reaction, if the control rod 1 is simply shortened, the value of the control rod is reduced accordingly, and for example, the reactor shutdown margin becomes insufficient. Moreover, when the reactor is shut down, all the control rods 1 are inserted into the core 11, and the reactor is in a subcritical state. However, in this reactor shutdown state, one of the control rods 1 is removed from the core 11 It is required that the reactor be subcritical even after being pulled out.
【０００８】なお、制御棒価値の最も大きい制御棒１を
引抜けた時の未臨界度が炉停止余裕である。また緊急時
における原子炉停止機能については、炉心11の下端から
全炉心長の約60％まで、制御棒１が急速に挿入されれば
機能は達成されるので、冷態停止時の炉停止余裕に比べ
れば制御棒短尺化に対する制限とはならない。The subcriticality when the control rod 1 having the greatest control rod value is pulled out is the reactor shutdown margin. Regarding the reactor shutdown function in an emergency, the function can be achieved if the control rod 1 is rapidly inserted from the lower end of the core 11 to about 60% of the total core length. Compared with the above, it is not a limitation for shortening the length of the control rod.
【０００９】本発明の目的とするところは、制御棒の設
計に当たり、燃料集合体における燃料有効長とバランス
する制御棒有効長として、良好な制御特性を維持して制
御棒を短尺化すると共に、これに付随する制御棒案内
管、制御棒駆動機構ハウジングおよび原子炉圧力容器等
を短縮可能として、耐震性の向上とコストダウンされた
原子炉を提供することにある。An object of the present invention is to design a control rod so that the control rod effective length is balanced with the fuel active length in the fuel assembly to maintain good control characteristics and shorten the control rod. A control rod guide tube, a control rod drive mechanism housing, a reactor pressure vessel and the like which are associated therewith can be shortened to provide a nuclear reactor with improved seismic resistance and reduced cost.
【００１０】[0010]
【課題を解決するための手段】燃料棒を多数本配列した
燃料バンドルをチャンネルボックスで包囲して構成した
燃料集合体を多数体配列すると共に燃料集合体間に中性
子吸収材からなる制御棒を下部より挿抜可能に設けて前
記燃料棒の反応度を制御する原子炉において、前記燃料
集合体は軸方向に少なくとも２以上の領域に分かれてい
て、冷態時における最上部領域の反応度がこの最上部以
外の領域の反応度よりも小さく、かつ前記制御棒は全ス
トローク挿入時において中性子吸収材の上端が燃料集合
体の前記最上部領域の下端乃至この下端より下方に位置
させたことを特徴とする。A plurality of fuel assemblies, each of which is formed by surrounding a fuel bundle in which a plurality of fuel rods are arranged in a channel box, are arranged, and a control rod made of a neutron absorbing material is formed between the fuel assemblies. In a nuclear reactor that is more removably installed and controls the reactivity of the fuel rods, the fuel assembly is divided into at least two regions in the axial direction, and the reactivity of the uppermost region in the cold state is the highest. Less than the reactivity of the region other than the upper portion, and the control rod is characterized in that the upper end of the neutron absorber is positioned below the lower end or the lower end of the uppermost region of the fuel assembly at the time of full stroke insertion. To do.
【００１１】[0011]
【作用】燃料集合体の冷態時における最上部領域の反応
度を最上部以外の領域の反応度よりも小さくすることに
より、炉停止余裕を拡張確保される。これにより制御棒
を短尺化し、この短尺化した制御棒に付随する制御棒案
内管、制御棒駆動機構ハウジング等の短尺化により下部
プレナム長が短縮され原子炉圧力容器がコンパクトにな
り、原子炉圧力容器の重心位置が下がり耐震性が向上す
ると共に、コストダウンができる。The reactor shutdown margin can be expanded and secured by making the reactivity of the uppermost region in the cold state of the fuel assembly smaller than the reactivity of the regions other than the uppermost region. As a result, the control rod is shortened, and the control rod guide tube, control rod drive mechanism housing, etc. attached to this shortened control rod are shortened, which shortens the lower plenum length and makes the reactor pressure vessel compact. The center of gravity of the container is lowered to improve the earthquake resistance and the cost can be reduced.
【００１２】[0012]
【実施例】本発明の一実施例を図面を参照して説明す
る。なお、上記した従来技術と同じ構成部分については
同一符号を付して詳細な説明を省略する。第１の実施例
における燃料集合体と制御棒の関係は、図１の燃料と制
御棒の有効長構成図で示すように、燃料集合体20の燃料
有効長21に対する制御棒40の制御棒有効長41は、炉心下
部方向から全ストローク挿入された時の位置関係が、燃
料集合体20は上部に低反応度燃料として天然ウランによ
る上部ブランケット22を、下部には濃縮燃料部23を配置
した構成で、これに対して制御棒40の制御棒有効長41で
ある中性子吸収体の上端が前記燃料集合体20の上部ブラ
ンケット22の下端、乃至は下端より下方に位置するよう
に構成されている。DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. It should be noted that the same components as those of the above-described conventional technique are denoted by the same reference numerals and detailed description thereof will be omitted. The relationship between the fuel assembly and the control rods in the first embodiment is as shown in the fuel and control rod active length configuration diagram of FIG. The length 41 is the positional relationship when the entire stroke is inserted from the lower part of the core, the fuel assembly 20 has an upper blanket 22 made of natural uranium as a low reactivity fuel in the upper part, and a concentrated fuel part 23 in the lower part. On the other hand, the upper end of the neutron absorber, which is the control rod effective length 41 of the control rod 40, is located below the lower end of the upper blanket 22 of the fuel assembly 20 or below the lower end.
【００１３】次に上記構成による作用について説明す
る。上記構成は冷態時の制御棒引抜き量と炉停止余裕の
関係の評価からなされたものであって、図２は制御棒の
引抜き量に対する炉停止余裕の変化の特性図で、横軸は
全制御棒が上部ブランケット22の下端から引抜かれた距
離を、縦軸は上部ブランケット22のない燃料集合体によ
る炉心における炉停止余裕を基準にした炉停止余裕の変
化（％Δｋ）を示している。Next, the operation of the above configuration will be described. The above-mentioned configuration was made by evaluating the relationship between the control rod withdrawal amount and the furnace shutdown margin in the cold state. Fig. 2 is a characteristic diagram of the change in the furnace shutdown margin with respect to the control rod withdrawal amount, and the horizontal axis represents all The control rod is pulled out from the lower end of the upper blanket 22, and the vertical axis shows the change (% Δk) in the reactor shutdown margin based on the reactor shutdown margin in the core due to the fuel assembly without the upper blanket 22.
【００１４】なお、図中の各曲線BL1 ，BL2 ，BL3 と交
わる斜線部は、上部ブランケット22と濃縮燃料部23との
境界で、斜線部より左が上部ブランケット領域で右が濃
縮燃料領域に相当する。ここで曲線BLO は上部ブランケ
ット22を有しない燃料集合体による炉心で、曲線BL1 ，
BL2 ，およびBL3 は、夫々上部ブランケット22の厚さを
６，12，および24インチとした燃料集合体20による炉心
の場合を示す。It should be noted that the shaded portion intersecting each of the curves BL 1 , BL 2 , BL 3 in the figure is the boundary between the upper blanket 22 and the concentrated fuel portion 23. Corresponds to the area. Here, the curve BL O is the core of the fuel assembly without the upper blanket 22, and the curves BL 1 ,
BL 2 and BL 3 show the case of the core with the fuel assembly 20 in which the thickness of the upper blanket 22 is 6, 12 and 24 inches, respectively.
【００１５】この図２によれば制御棒の引抜き量が同じ
である場合には、上部ブランケット22が厚いほど曲線BL
O に示す基準炉心より炉停止余裕は増えている。すなわ
ち、曲線BLO では全制御棒を引抜き始めると直ぐに炉停
止余裕が悪化する。しかしながら、上部ブランケット22
の厚さが６インチの場合の曲線BL1 では、全制御棒が上
部ブランケット22の下端まで、すなわち６インチ引抜か
れても炉停止余裕はほとんど変化せず、更に２〜３イン
チ引抜いても炉停止余裕の悪化は小さい。According to FIG. 2, when the pulling out amount of the control rod is the same, the thicker the upper blanket 22 is, the curve BL
The reactor shutdown margin has increased from the reference core shown in O. In other words, immediately reactor shutdown margin is deteriorated and begin to pull out all the control rods in the curve BL O. However, the upper blanket 22
In the case of the curve BL 1 when the thickness is 6 inches, even if all the control rods are withdrawn to the lower end of the upper blanket 22, that is, withdrawal by 6 inches, there is almost no change in the furnace shutdown margin. The deterioration of the stop margin is small.
【００１６】また曲線BL2 は上部ブランケット22の厚さ
を12インチとした燃料集合体20による炉心であるが、曲
線BL1 の場合と同様に全制御棒を上部ブランケット22の
下端まで引抜いても炉停止余裕はほとんど変化せず、上
部ブランケット22の下端から更に２〜３インチ引き抜い
ても炉停止余裕の悪化は少ない。さらに、上部ブランケ
ット22の厚さを24インチとした曲線BL3 においても同様
の結果が得られる。Further, the curve BL 2 is the core of the fuel assembly 20 in which the thickness of the upper blanket 22 is 12 inches, but even if all the control rods are pulled out to the lower end of the upper blanket 22 as in the case of the curve BL 1. The furnace shutdown margin remains almost unchanged, and even if the upper blanket 22 is further pulled out by 2 to 3 inches from the lower end, the deterioration of the furnace shutdown margin is small. Further, the same result is obtained also in the curve BL 3 in which the thickness of the upper blanket 22 is 24 inches.
【００１７】以上のように、燃料集合体の燃料有効長21
の上部領域において冷態時に反応度の低い燃料、例えば
天然ウランによるブランケット22を組合わせた燃料集合
体20による炉心においては、制御棒40を炉心の下方より
挿入した場合に、制御棒40の有効部の上端が上部ブラン
ケット22の下端と同じ程度か、これよりもやや下方にあ
っても炉停止余裕の悪化はほとんど無いことが分かる。
従って、制御棒40は従来例の制御棒１よりも上部ブラン
ケット厚さ＋αの短尺化が可能となる。As described above, the active fuel length of the fuel assembly is 21
In the core of the fuel assembly 20 in which a fuel having a low reactivity in a cold state in the upper region of, for example, the blanket 22 made of natural uranium is combined, the control rod 40 is effective when the control rod 40 is inserted from below the core. It can be seen that even if the upper end of the part is about the same as the lower end of the upper blanket 22 or slightly lower than this, there is almost no deterioration in the reactor shutdown margin.
Therefore, the control rod 40 can be made shorter than the conventional control rod 1 by the upper blanket thickness + α.
【００１８】例えば、上部ブランケット22の厚さを12イ
ンチとした場合では、従来約 144インチの制御棒を12イ
ンチ以上短くすることができる。さらに、制御棒の12イ
ンチ以上の短尺化に伴い、前記制御棒案内管14および制
御棒駆動機構ハウジング15も約12インチずつ短縮できる
ので、従来約20ｍ高さの原子炉圧力容器10を約60cm低く
でき、また重心位置を約90cm下方にシフトさせることが
可能となった。For example, when the thickness of the upper blanket 22 is 12 inches, the conventional control rod of about 144 inches can be shortened by 12 inches or more. Further, as the control rod is shortened to 12 inches or more, the control rod guide tube 14 and the control rod drive mechanism housing 15 can be shortened by about 12 inches, so that the conventional reactor pressure vessel 10 having a height of about 20 m is about 60 cm. It was possible to lower the height and shift the center of gravity downward by about 90 cm.
【００１９】図３の燃料と制御棒の有効長構成図は上記
第１の実施例の変形例で、燃料集合体24が最上部の上部
ブランケット22に加えて最下部にも下部ブランケット25
を設け、この間を２領域に分割して、上に高反応度燃料
26、下に低反応度燃料27を配置した構成のもので、制御
棒40は上記第１の実施例と同様に燃料集合体24の上部ブ
ランケット22の下端あるいは、この下端以下の長さに単
尺化した制御棒有効長41のものを組合わせている。The structure of the active lengths of the fuel and control rods in FIG. 3 is a modification of the first embodiment, in which the fuel assembly 24 has the upper blanket 22 at the uppermost portion and the lower blanket 25 at the lowermost portion.
Is installed, and the space between them is divided into two areas, and high reactivity fuel is
26, the low-reactivity fuel 27 is disposed below the control rod 40, and the control rod 40 has a length equal to or lower than the lower end of the upper blanket 22 of the fuel assembly 24 as in the first embodiment. A control rod with an effective length of 41 is combined.
【００２０】さらに、図４の燃料と制御棒の有効長構成
図は、上記図３と同じく第１の実施例の他の変形例を示
すもので、燃料集合体28は上部ブランケット22と下部ブ
ランケット25の中間を３領域に分割し、上に低反応度燃
料27、中間に高反応度燃料26、下に中反応度燃料29を配
置している。この場合も制御棒40は上記第１の実施例と
同様に燃料集合体28の上部ブランケット22の下端あるい
は、この下端以下の長さの制御棒有効長41とした単尺化
した制御棒40を組合わせて構成としている。以上図３お
よび図４に示す２つの変形例のように、燃料有効長にお
いて反応度の異なる燃料を種々組合わせて配置した燃料
集合体24，28としても、最上部に上部ブランケット22を
設けた構成とすれば、図１に示す上記一実施例と同様な
作用と効果が得られる。Further, the effective length configuration diagram of the fuel and control rods in FIG. 4 shows another modification of the first embodiment as in the case of FIG. 3, in which the fuel assembly 28 includes an upper blanket 22 and a lower blanket. The middle portion of 25 is divided into three regions, and the low reactivity fuel 27 is arranged above, the high reactivity fuel 26 is arranged in the middle, and the middle reactivity fuel 29 is arranged below. In this case as well, the control rod 40 is the single control rod 40 having the lower end of the upper blanket 22 of the fuel assembly 28 or the effective control rod length 41 of a length equal to or shorter than the lower end as in the first embodiment. It is configured in combination. As in the two modifications shown in FIGS. 3 and 4, the upper blanket 22 is provided at the uppermost portion of the fuel assemblies 24 and 28 in which fuels having different reactivity in the active fuel length are arranged in various combinations. With the configuration, the same operation and effect as those of the above-described embodiment shown in FIG. 1 can be obtained.
【００２１】図５の燃料集合体の横断面図は、本発明の
第２の実施例を示すもので、上記第１の実施例では冷態
時における最上部の反応度を下げる手段として、上部ブ
ランケット22に天然ウランを採用したことを例示した
が、図５に示すように燃料集合体30の最上部領域におい
て燃料棒３の本数を、最上部領域以外の領域の燃料棒本
数と比べて少なくすることでも同様の効果が得られる。
すなわち、燃料集合体30においては、制御棒40に対峙す
る面の最上部領域の燃料棒３を取り除いた構成としてい
る。The cross-sectional view of the fuel assembly shown in FIG. 5 shows the second embodiment of the present invention. In the first embodiment, the upper part is used as a means for lowering the reactivity of the uppermost part in the cold state. Although it has been illustrated that natural uranium is used for the blanket 22, as shown in FIG. 5, the number of fuel rods 3 in the uppermost region of the fuel assembly 30 is smaller than the number of fuel rods in the regions other than the uppermost region. By doing so, the same effect can be obtained.
That is, in the fuel assembly 30, the fuel rod 3 in the uppermost region of the surface facing the control rod 40 is removed.
【００２２】この構成によれば、燃料集合体30の上部に
おいて、出力運転時には燃料棒３の発熱により中性子減
速材兼冷却材である水が約70％のボイドを含んでいるた
め、減速材が不足した状態にあり、削除した燃料棒３の
分だけ水が若干増えて、中性子の減速状態が改善される
ため、反応度の低下は小さく運転時の支障にはならな
い。しかし冷態時にはボイドの発生がないので、削除し
た燃料棒３の体積相当分の水が増加して、水による中性
子の寄生吸収割合が多くなり反応度が減少するため炉停
止余裕の確保に有効に作用する。According to this structure, in the upper portion of the fuel assembly 30, since the water which is the neutron moderator / coolant contains about 70% of voids due to the heat generation of the fuel rod 3 during the output operation, the moderator is There is a shortage of water, the amount of water is increased by the amount of the removed fuel rods 3, and the deceleration state of neutrons is improved, so that the decrease in reactivity is small and does not hinder operation. However, since voids do not occur in the cold state, the water equivalent to the volume of the removed fuel rods 3 increases, the parasitic absorption ratio of neutrons by water increases, and the reactivity decreases, so it is effective in securing the reactor shutdown margin. Act on.
【００２３】なお、このような作用、効果は燃料集合体
30の断面内の中心付近の燃料棒３を削除しても得られる
が、中心付近よりも周辺の燃料棒３を取り去った方が顕
著であり、これは、もともと燃料と燃料の間の領域は水
が充満しているためで、この近くで水が増すことによっ
て、その中性子吸収効果が特に大きくなるからである。
従って、燃料集合体30の最上部領域の燃料棒本数を少な
くすることでも冷態時における最上部領域の反応度を下
げることができ、上記第１の実施例で説明したように制
御棒の短尺化が達成できる。The above-described action and effect are obtained by the fuel assembly.
It can be obtained by removing the fuel rods 3 near the center in the cross section of 30, but it is more noticeable to remove the fuel rods 3 around the center than in the vicinity of the center. This is because the water is full, and the neutron absorption effect becomes particularly large as the water increases in the vicinity.
Therefore, by reducing the number of fuel rods in the uppermost region of the fuel assembly 30, the reactivity of the uppermost region in the cold state can be lowered, and as described in the first embodiment, the length of the control rod is short. Can be achieved.
【００２４】[0024]
【発明の効果】以上本発明によれば、炉停止余裕を良好
にして制御棒の短尺化が可能であり、これによって制御
棒に付随する制御棒案内管、制御棒駆動機構ハウジング
等も短尺化でき、その結果、下部プレナム長が短縮され
て原子炉圧力容器がコンパクトになりコストダウンされ
る。同時に制御棒駆動機構ハウジング、および原子炉圧
力容器の短尺化により原子炉格納容器における炉心の重
心位置が下がり耐震性が向上する効果がある。As described above, according to the present invention, it is possible to shorten the length of the control rod by improving the furnace shutdown margin, and thereby shorten the length of the control rod guide tube, the control rod drive mechanism housing, etc. attached to the control rod. As a result, the length of the lower plenum is shortened, the reactor pressure vessel is made compact, and the cost is reduced. At the same time, by shortening the control rod drive mechanism housing and the reactor pressure vessel, the center of gravity of the reactor core in the reactor containment vessel is lowered, and seismic resistance is improved.
【図１】本発明の第１の実施例に係る燃料と制御棒の有
効長構成図。FIG. 1 is an effective length configuration diagram of a fuel and a control rod according to a first embodiment of the present invention.
【図２】本発明の第１の実施例に係る制御棒の引抜き量
に対する炉停止余裕の変化の特性図。FIG. 2 is a characteristic diagram of changes in the reactor shutdown margin with respect to the withdrawal amount of the control rod according to the first embodiment of the present invention.
【図３】本発明の第１の実施例に係る変形例の燃料と制
御棒の有効長構成図。FIG. 3 is a configuration diagram of a fuel and a control rod effective length according to a modification of the first embodiment of the present invention.
【図４】本発明の第１の実施例に係る他の変形例の燃料
と制御棒の有効長構成図。FIG. 4 is a configuration diagram of an effective length of a fuel and a control rod of another modified example according to the first embodiment of the present invention.
【図５】本発明の第２の実施例に係る燃料集合体と制御
棒の横断面図。FIG. 5 is a cross sectional view of a fuel assembly and a control rod according to a second embodiment of the present invention.
【図６】従来の燃料集合体と制御棒の横断面図。FIG. 6 is a cross-sectional view of a conventional fuel assembly and control rod.
【図７】全炉心の第２象限配置図。FIG. 7 is a second quadrant layout diagram of the entire core.
【図８】制御棒の斜視図。FIG. 8 is a perspective view of a control rod.
【図９】従来の燃料と制御棒の有効長構成図。FIG. 9 is a configuration diagram of a conventional fuel and control rod effective length.
【図１０】沸騰水型原子炉の縦断面図。FIG. 10 is a vertical cross-sectional view of a boiling water reactor.
２…Ｂ4 Ｃの棒、３…燃料棒、10…原子炉圧力容器、13
…下部プレナム、14…制御棒案内管、15…制御棒駆動機
構ハウジング、16…制御棒駆動機構、20，24，28，30…
燃料集合体、21…燃料有効長、22…上部ブランケット、
23…濃縮燃料部、25…下部ブランケット、26…高反応度
燃料、27…低反応度燃料、29…中反応度燃料、40…制御
棒、41…制御棒有効長。2 ... B 4 C rod, 3 ... fuel rod, 10 ... reactor pressure vessel, 13
… Lower plenum, 14… Control rod guide tube, 15… Control rod drive mechanism housing, 16… Control rod drive mechanism, 20, 24, 28, 30…
Fuel assembly, 21 ... Effective fuel length, 22 ... Upper blanket,
23 ... concentrated fuel part, 25 ... lower blanket, 26 ... high reactivity fuel, 27 ... low reactivity fuel, 29 ... medium reactivity fuel, 40 ... control rod, 41 ... control rod effective length.
Claims (1)
チャンネルボックスで包囲して構成した燃料集合体を多
数体配列すると共に燃料集合体間に中性子吸収材からな
る制御棒を下部より挿抜可能に設けて前記燃料棒の反応
度を制御する原子炉において、前記燃料集合体は軸方向
に少なくとも２以上の領域に分かれていて、冷態時にお
ける最上部領域の反応度がこの最上部以外の領域の反応
度よりも小さく、かつ前記制御棒は全ストローク挿入時
において中性子吸収材の上端が燃料集合体の前記最上部
領域の下端乃至この下端より下方に位置させたことを特
徴とする原子炉。1. A fuel rod having a plurality of fuel rods arranged in a channel box is surrounded by a channel box to arrange a plurality of fuel assemblies, and a control rod made of a neutron absorbing material can be inserted and removed between the fuel assemblies from below. In the reactor for controlling the reactivity of the fuel rod, the fuel assembly is divided into at least two regions in the axial direction, and the reactivity of the uppermost region in the cold state is a region other than this uppermost region. And the control rod is positioned such that the upper end of the neutron absorber is located at the lower end of the uppermost region of the fuel assembly or below the lower end when the full stroke is inserted.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02223392A JP3167771B2 (en) | 1992-02-07 | 1992-02-07 | Reactor and fuel assemblies |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02223392A JP3167771B2 (en) | 1992-02-07 | 1992-02-07 | Reactor and fuel assemblies |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05215881A true JPH05215881A (en) | 1993-08-27 |
| JP3167771B2 JP3167771B2 (en) | 2001-05-21 |
Family
ID=12077077
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP02223392A Expired - Lifetime JP3167771B2 (en) | 1992-02-07 | 1992-02-07 | Reactor and fuel assemblies |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3167771B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008116447A (en) * | 2006-10-31 | 2008-05-22 | Global Nuclear Fuel Americas Llc | Method for improving energy output of nuclear reactor, method for determining natural uranium blanket layer for fuel bundle and fuel bundle with variable blanket layer |
-
1992
- 1992-02-07 JP JP02223392A patent/JP3167771B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008116447A (en) * | 2006-10-31 | 2008-05-22 | Global Nuclear Fuel Americas Llc | Method for improving energy output of nuclear reactor, method for determining natural uranium blanket layer for fuel bundle and fuel bundle with variable blanket layer |
| US20080137792A1 (en) * | 2006-10-31 | 2008-06-12 | David Joseph Kropaczek | Method for improving energy output of a nuclear reactor, method for determining natural uranium blanket layer for a fuel bundle, and a fuel bundle having a variable blanket layer |
| US8582713B2 (en) | 2006-10-31 | 2013-11-12 | Global Nuclear Fuel-Americas, Llc | Method for improving energy output of a nuclear reactor, method for determining natural uranium blanket layer for a fuel bundle, and a fuel bundle having a variable blanket layer |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3167771B2 (en) | 2001-05-21 |
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