JPH0280998A - Natural recirculation type boiling water reactor - Google Patents

Abstract

PURPOSE:To enhance natural recirculation power by connecting the extensible pipe extended into reactor pressure vessel to the connection part to a downcomer of a water supply pipe and directly and forcibly allowing a cooling material to flow downwardly in the downcomer. CONSTITUTION:In this boiling water reactor, an extension pipe 10 having a length suspended in a downcomer 7 from the outlet of a water supply pipe 5 to reach a core 2 is connected to the outlet of the water supply pipe 5. Therefore, forcible flow force is applied up to the terminal opening part of the vertical downward extension pipe 10. Natural recirculation power such that a fluid lump having a sub-cool degree is held up to a relatively lower part and natural recirculation power is easy to apply in a local place is enhanced. Further, so called bypass phenomenon such that no downward stream is generated between the water supply pipe 10 and other water supply pipe present at the same level and inflow/outflow is generated between the water supply pipes can be prevented.

Description

【発明の詳細な説明】 ［発明の目的］ （産業上の利用分野） 本発明は定常状態において自然循環によって冷却材を回
流する自然画環形沸騰水型原子炉に関する。DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a natural ring boiling water nuclear reactor in which a coolant is circulated by natural circulation in a steady state.

（従来の技術） 自然画環形沸騰水型原子炉は定常状態で循環ポンプを使
用しないで、自然循環で冷却材を回流させることによっ
て炉心からの熱を除去し、蒸気を発生させるものである
。発生した蒸気をタービン建屋まで送ることによって発
電に寄与させ、復水器で復水し、この復水を脱塩ろ過し
て給水管を通して原子炉圧力容器へ戻す流路は強制循環
形沸騰水型原子力発電プラントと同じである。(Prior Art) A natural ring type boiling water reactor does not use a circulation pump in a steady state, but instead uses natural circulation to circulate the coolant to remove heat from the core and generate steam. The generated steam is sent to the turbine building to contribute to power generation, condensed in a condenser, desalinated and filtered, and returned to the reactor pressure vessel through a water supply pipe. The flow path is a forced circulation boiling water type. It is the same as a nuclear power plant.

第３図は従来の自然画環形沸騰水型原子炉の線図的概略
断面図で、この第３図を参照しながら従来例を説明する
。FIG. 3 is a schematic cross-sectional diagram of a conventional natural ring type boiling water nuclear reactor, and the conventional example will be explained with reference to FIG.

第３図中、符号１は原子炉圧力容器で、この原子炉圧力
容器１内には炉心２が配置されている。In FIG. 3, reference numeral 1 denotes a reactor pressure vessel, and a reactor core 2 is disposed within this reactor pressure vessel 1.

この炉心２の下方には制御棒３が設けられている。Control rods 3 are provided below this core 2 .

また、原子炉圧力容器１の上部には主蒸気管４および給
水管５が接続されている。炉心２の外側を包囲し、前記
給水管５の若干上方までにわたってシュラウド（ライザ
）６が設けられている。シュラウド６の外側と原子炉圧
力容器１との間には円環状領域のダウンカマ７が形成さ
れている。なお、図示していないが原子炉圧力容器１内
の上部には気水分離器と蒸気乾燥器とが設けられている
。Further, a main steam pipe 4 and a water supply pipe 5 are connected to the upper part of the reactor pressure vessel 1. A shroud (riser) 6 is provided surrounding the outside of the reactor core 2 and extending slightly above the water supply pipe 5 . A downcomer 7 having an annular shape is formed between the outside of the shroud 6 and the reactor pressure vessel 1 . Although not shown, a steam separator and a steam dryer are provided in the upper part of the reactor pressure vessel 1.

一般に再循環ポンプを使用する強制循環形沸騰水型原子
炉は炉心内で発生する慶を沸騰伝熱によって除去するも
ので、炉心上部では二相流状態となる。この二相流は気
水分離器によって水と蒸気に分離され、その蒸気は蒸気
乾燥器によって乾燥蒸気となる。この乾燥蒸気は主蒸気
管からタービンに送られ、タービンを駆動する。しかし
、第３図に示した自然画環形沸騰水型原子炉ではタービ
ンで仕事をした後の復水が原子炉圧力容器内に戻り、冷
却材として炉心へ流れ込む円環状アニユラス空間領域の
ダウンカマ７は単相流の冷却材（水）で満たされている
。そのため、炉心２とダウンカマ７の双方に共有した液
の自由界面８を有する場合、炉心２とダウンカマ７の水
頭が異なることによる自然循環力がつき、この浮力によ
って自然に回流することができる。In general, forced circulation boiling water reactors that use recirculation pumps remove the gas generated within the core by boiling heat transfer, resulting in a two-phase flow state in the upper part of the core. This two-phase flow is separated into water and steam by a steam separator, and the steam is turned into dry steam by a steam dryer. This dry steam is sent to the turbine through the main steam pipe and drives the turbine. However, in the natural annular boiling water reactor shown in Figure 3, the condensate after working in the turbine returns to the reactor pressure vessel and flows into the reactor core as a coolant. It is filled with coolant (water) in a single phase flow. Therefore, when both the core 2 and the downcomer 7 have a shared free interface 8, a natural circulation force is generated due to the difference in the water heads of the core 2 and the downcomer 7, and this buoyancy allows for natural circulation.

冷却材の原子炉圧力容器内外で一巡する流れは炉心２．
シュラウド６部、炉外のタービン、復水部、ダウンカマ
７に大別でき、これらを質点抵抗によって大雑把に模擬
してその流動特性を評価することができる。The flow of coolant that circulates inside and outside the reactor pressure vessel is carried out in the core 2.
It can be roughly divided into the shroud 6, the turbine outside the reactor, the condensate section, and the downcomer 7, and these can be roughly simulated using mass point resistance to evaluate their flow characteristics.

（発明が解決しようとする課題） 従来の自然画環形沸騰水型原子炉では給水管５から流入
した冷却材は直ちにそのレベルでダウンカマ７内に解放
されている。実際はスパージャの状態で噴出され、ダウ
ンカマ、つまりアニユラス部で混合するうちに水温を高
めながら流下していく。(Problems to be Solved by the Invention) In the conventional natural ring type boiling water reactor, the coolant flowing from the water supply pipe 5 is immediately released into the downcomer 7 at that level. In reality, the water is ejected in the form of a sparger, and as it mixes in the downcomer, or annulus, it flows down while increasing the water temperature.

今、自然循環流をｍ、水頭を目、長さスケールをり、比
重量をＴとして、炉心・シュラウド・炉外（−括）・ダ
ウンカマ各部をＣ，Ｒ，Ｔ、Ｄの添字で示すと、運動伍
保存より次式が成り立つ。Now, let's say that the natural circulation flow is m, the water head is 2, the length scale is 2, the specific weight is T, and the core, shroud, outside the reactor (in parentheses), and downcomer parts are indicated by subscripts C, R, T, and D. , the following equation holds from the conservation of motion.

上式の他に各種バランスの式を用いると自然循環量は以
下の式で示される（式の導入など詳細は省略）。ここで
、Ｊは重力加速度、Ａは流路面積。Using various balance formulas in addition to the above formula, the natural circulation amount can be expressed by the following formula (details such as the introduction of formulas are omitted). Here, J is the gravitational acceleration and A is the flow path area.

Ｋ、ｆは摩擦係数である。K and f are friction coefficients.

ｍ２＝’；ｊ　（ＬＲ＋ＬＤ　＞　（γＤ−γＲ）この
自然循環力はシュラウド部の高さを高くする（ＬＲ大）
、サブクール度を付ける（γＤ大）なとの工夫によりｍ
の値を増すことができるが、いまダウンカマに注目した
場合、単相水のダウンカマへの供給方法によって自然循
環性能を変化させることができる。発電の性格上、自然
循環力がつくほど発電量の増加が見込まれるため除熱能
力を増すことが望ましい。m2=';j (LR+LD > (γD-γR)) This natural circulation force increases the height of the shroud (LR large)
, by adding a subcool degree (large γD), m
However, if we focus on the downcomer, the natural circulation performance can be changed by the method of supplying single-phase water to the downcomer. Due to the nature of power generation, the amount of power generated is expected to increase as the natural circulation force increases, so it is desirable to increase the heat removal capacity.

本発明は以上の課題提起に鑑みてなされたもので、ダウ
ンカマでの循環力の増強、すなわち蒸気の式中の添字り
を示した項の改良に関し、ｍを大にするためにγｏ　Ｈ
ｏの項を大きくして、自然循環力を向上ざぜ、ダウンカ
マに過大な衝突時の動圧が働くことがなく、同一レベル
にある他の給水管の間で発生するバイパス現象を防止す
ることができる自然画環形沸騰水型原子炉を提供するこ
とにある。The present invention has been made in view of the above-mentioned problems, and relates to enhancement of the circulation force in the downcomer, that is, improvement of the subscripted term in the steam equation.In order to increase m, γo H
By increasing the term o, the natural circulation force is improved, excessive dynamic pressure does not act on the downcomer during a collision, and the bypass phenomenon that occurs between other water supply pipes at the same level can be prevented. The objective is to provide a natural ring boiling water reactor that can be used.

［発明の構成］ （課題を解決するための手段） 本発明は上部に主蒸気管および給水管が接続された原子
炉容器と、この原子炉圧力容器内に配置された炉心と、
この炉心を包囲しかつ前記給水管が接続された位置の近
傍まで延在するシュラウドと、このシュラウドの外側と
前記原子炉圧力容器の内側との間に形成された円環状で
かつ単相流水が供給されるダウンカマとからなり、前記
ダウンカマ内に前記給水管の出口側から前記炉心近傍ま
で垂下する延長管を設けたことを特徴とする。[Structure of the Invention] (Means for Solving the Problem) The present invention comprises a reactor vessel to which a main steam pipe and a water supply pipe are connected to the upper part, a reactor core disposed within the reactor pressure vessel,
A shroud that surrounds the reactor core and extends to the vicinity of the location where the water supply pipes are connected, and an annular and single-phase flowing water that is formed between the outside of the shroud and the inside of the reactor pressure vessel. The downcomer is supplied with a downcomer, and is characterized in that an extension pipe is provided inside the downcomer and extends from the outlet side of the water supply pipe to the vicinity of the reactor core.

（作　用） 炉心と同心で、円環状かつ単相水が供給されるダウンカ
マ内に設けた延長管を炉心下端近傍のレベル近くまで延
長し、この延長管を通して給水管からの冷却材は炉心近
傍の冷却材と混合されて解放される。ダウンカマに連通
ずる給水管は主蒸気管を通ってタービン建屋に送られる
質は流量と相等しい量が復水した単相の水となって補給
される。(Function) An extension pipe installed in the downcomer, which is concentric with the reactor core and has an annular shape and is supplied with single-phase water, is extended to a level near the lower end of the reactor core, and through this extension pipe, the coolant from the water supply pipe is delivered to the vicinity of the reactor core. coolant and released. The water supply pipe connected to the downcomer is supplied through the main steam pipe to the turbine building in the form of condensed single-phase water in an amount equal to the flow rate.

したがって、自然循環力が向上することになる。Therefore, the natural circulation force will be improved.

（実施例） 第１図を参照しながら本発明に係る原子炉の第１の実施
例を説明する。第１図において、第３図と同一部分は同
一符号で示し、重複する部分の説明を省略する。(Example) A first example of a nuclear reactor according to the present invention will be described with reference to FIG. In FIG. 1, the same parts as in FIG. 3 are indicated by the same reference numerals, and the explanation of the overlapping parts will be omitted.

この実施例が第３図の従来例と異なる部分は給水管５の
出口側からダウンカマ７内に垂下して炉心２に到るまで
の長さを有する延長管１０を給水管５の出口側に接続し
たことにある。その他の部分は第３図と同様である。The difference between this embodiment and the conventional example shown in FIG. It's about connecting. Other parts are the same as in FIG. 3.

この実施例では給水管５のダウンカマ７への接続部に下
方に長く延長し炉心２の下方近くに開放する延長管１０
を接続しているために鉛直下方延長管１０の端末開口部
まで強制流動力が印加される。In this embodiment, an extension pipe 10 is provided at the connection part of the water supply pipe 5 to the downcomer 7 and extends downward for a long time and opens near the bottom of the reactor core 2.
Because of the connection, forced flow force is applied to the terminal opening of the vertically downward extension tube 10.

また、サブクール度を有する流体塊が比較的下方まで保
たれ、局所的に自然循環力をつけやすいなど、自然循環
力が向上する。この実施例の効果は前記の式（１）の左
辺においてＴｏ、Ｈｏの項を人為的に大としたことに相
当することからも明らかである。また、従来例では給水
管からの流入部近傍のシュラウド６に過大な動圧が働く
が、この実施例では給水管７の出口側に接続し下方へ折
り曲げてダウンカマ７内に下降する延長管１０の１字状
直角部分が担うことになり、シュラウド６自体の健全性
に資することになる。更に、同一レベルにある他の給水
管との間で下流に向うことなく給水管同士で流出入が発
生するいわゆるバイパス現象を防止することができる。In addition, the fluid mass having a subcool degree is maintained relatively downward, making it easier to apply natural circulation force locally, thereby improving the natural circulation force. The effect of this embodiment is also clear from the fact that it corresponds to artificially increasing the terms To and Ho on the left side of equation (1). In addition, in the conventional example, excessive dynamic pressure acts on the shroud 6 near the inflow part from the water supply pipe, but in this embodiment, an extension pipe 10 is connected to the outlet side of the water supply pipe 7 and bent downward to descend into the downcomer 7. This is carried out by the right-angled portion of the shroud 6, which contributes to the soundness of the shroud 6 itself. Furthermore, it is possible to prevent the so-called bypass phenomenon in which water flows into and out of water supply pipes without going downstream between them and other water supply pipes on the same level.

第２図は本発明の第２の実施例を示したもので、第１図
と同一部分は同一符号で示し、重複する部分の説明を省
略する。FIG. 2 shows a second embodiment of the present invention, in which the same parts as in FIG. 1 are designated by the same reference numerals, and the explanation of the overlapping parts will be omitted.

この第２の実施例が第１の実施例と異なる部分は延長管
１０の端末開口部に炉心２の下方から冷却材を流入する
ための補助管１１を接続したことにある。この第２の実
施例においては炉心２の冷却材と延長管１０から流入し
た冷却材との混合が遅くなり、Ｔｏを大きく保つことが
できる。その他の作用効果は第１の実施例と同様なので
その説明を省略する。The difference between the second embodiment and the first embodiment is that an auxiliary pipe 11 for flowing coolant from below the core 2 is connected to the end opening of the extension pipe 10. In this second embodiment, the mixing of the coolant in the core 2 and the coolant flowing in from the extension pipe 10 is delayed, and To can be kept large. The other effects are the same as those of the first embodiment, so their explanation will be omitted.

［発明の効果］ 本発明によれば、給水管のダウンカマへの接続部に原子
炉圧力容器内に引き伸ばす延長管を接続し、冷却材をダ
ウンカマ内で直接下方に強制流下させている。したがっ
て、　■自然循環力が向上し、　■ダウンカマへの過大
な衝突時の動圧が作用せず、　■同一レベルにある他の
給水管との間で発生するバイパス現象を防止できるなど
の効果がある。[Effects of the Invention] According to the present invention, an extension pipe extending into the reactor pressure vessel is connected to the connection portion of the water supply pipe to the downcomer, and the coolant is forced to flow directly downward within the downcomer. Therefore, ■The natural circulation force is improved, ■Excessive dynamic pressure does not act on the downcomer when it collides, and ■The bypass phenomenon that occurs with other water supply pipes at the same level can be prevented. be.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図および第２図は本発明に係る自然循環形沸騰水型
原子炉のそれぞれの実施例を線図的に示す概略断面図、
第３図は従来のこの種の原子炉を線図的に示すＲ略断面
図である。 １・・・原子炉圧力容器 ２・・・炉心 ３・・・制御棒 ４・・・主蒸気管 ５・・・給水管 ６・・・シュラウド ７・・・ダウンカマ ８・・・二相液面 １０・・・延長管 １１・・・補助管 （８７３３）代理人　弁理士　猪　股　祥　晃（ほか　
１名） 第 ！ 図 第 図 第 図1 and 2 are schematic sectional views diagrammatically showing respective embodiments of a natural circulation boiling water reactor according to the present invention;
FIG. 3 is a schematic sectional view diagrammatically showing a conventional nuclear reactor of this type. 1... Reactor pressure vessel 2... Core 3... Control rod 4... Main steam pipe 5... Water supply pipe 6... Shroud 7... Downcomer 8... Two-phase liquid level 10...Extension pipe 11...Auxiliary pipe (8733) Agent: Patent attorney Yoshiaki Inomata (and others)
1 person) Number! Figure Figure Figure

Claims (1)

【特許請求の範囲】[Claims] 上部に主蒸気管および給水管が接続された原子炉容器と
、この原子炉圧力容器内に配置された炉心と、この炉心
を包囲しかつ前記給水管が接続された位置の近傍まで延
在するシュラウドと、このシュラウドの外側と前記原子
炉圧力容器の内側との間に形成された円環状でかつ単相
流水が供給されるダウンカマとからなり、前記ダウンカ
マ内に前記給水管の出口側から前記炉心近傍まで垂下す
る延長管を設けたことを特徴とする自然循環形沸騰水型
原子炉。A reactor vessel to which a main steam pipe and a water supply pipe are connected to the upper part, a reactor core disposed within this reactor pressure vessel, and a reactor that surrounds this core and extends to the vicinity of the position where the water supply pipe is connected. It consists of a shroud and an annular downcomer formed between the outside of the shroud and the inside of the reactor pressure vessel and to which single-phase flowing water is supplied, and the downcomer is supplied with water from the outlet side of the water supply pipe into the downcomer. A natural circulation boiling water reactor characterized by an extension pipe that hangs down to the vicinity of the reactor core.