JP2008122143A - Boiling-water reactor of natural circulation type - Google Patents

Boiling-water reactor of natural circulation type Download PDF

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JP2008122143A
JP2008122143A JP2006304069A JP2006304069A JP2008122143A JP 2008122143 A JP2008122143 A JP 2008122143A JP 2006304069 A JP2006304069 A JP 2006304069A JP 2006304069 A JP2006304069 A JP 2006304069A JP 2008122143 A JP2008122143 A JP 2008122143A
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water
natural circulation
steam
reactor
downcomer
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JP4504343B2 (en
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Masao Chagi
雅夫 茶木
Yoshihiko Ishii
佳彦 石井
Masaya Otsuka
雅哉 大塚
Tomohiko Ikegawa
智彦 池側
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Hitachi GE Nuclear Energy Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a boiling water reactor of a natural circulation type which can reduce carry-under and can further accelerate the mixture of feedwater with recirculating water in a reactor vessel. <P>SOLUTION: In the boiling water reactor 20 of a natural circulation type, a core 1 and a rotary flow generator 9 are laid out in a reactor pressure vessel (RPV) 2. The rotary flow generator 9 has blade members 34 and is placed in a downcomer 8. Those blade members 34 are laid out in the downcomer 8, are mounted on the outside face of a cylindrical member 22 of a chimney 4 and are laid out at prescribed intervals in the circumferential direction. Each of the blade members 34 inclines circumferentially in the same direction. The cooling water flowing from a steam separation space 21 formed between the chimney 4 and a steam dryer 5 into the downcomer 8 is turned into rotary flows going downward by the inclination angles of the blade members 34. The installation of the rotary flow generator 9 makes it possible to separate the steam from the cooling water which has flowed into the downcomer 8 and to accelerate the mixture of the cooling water which has flowed into the downcomer 8 with feedwater. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、自然循環型沸騰水型原子炉に係り、特に、ダウンカマー内における気水分離機能を向上させるのに好適な自然循環型沸騰水型原子炉に関する。   The present invention relates to a natural circulation boiling water nuclear reactor, and more particularly to a natural circulation boiling water nuclear reactor suitable for improving a steam-water separation function in a downcomer.

沸騰水型原子炉では、冷却水（冷却材）は、原子炉圧力容器（以下、ＲＰＶという）内の炉心で加熱されて一部が蒸気になる。蒸気に含まれている水分が炉心上方に配置された気水分離器及び蒸気乾燥器により分離される。水分が除去された蒸気は、主蒸気配管により蒸気タービンに供給され、その後、復水器で凝縮されて水になる。この水は、給水として給水配管によりＲＰＶに供給される。沸騰水型原子炉は、運転時において炉心内及び炉心より上方では水と蒸気の二相流の状態になっている。   In a boiling water reactor, cooling water (coolant) is heated by a core in a reactor pressure vessel (hereinafter referred to as RPV), and a part thereof becomes steam. Moisture contained in the steam is separated by a steam / water separator and a steam dryer disposed above the core. The steam from which moisture has been removed is supplied to the steam turbine through the main steam pipe, and then condensed into water by the condenser. This water is supplied to the RPV through the water supply pipe as water supply. A boiling water reactor is in a two-phase flow state of water and steam in the core and above the core during operation.

特に、自然循環型沸騰水型原子炉は、冷却水を強制循環させる再循環ポンプ等を備えていなく、自然循環により冷却水を炉心に供給している。冷却水の自然循環力を高めるために、自然循環型沸騰水型原子炉は炉心の上方に筒状のチムニを配置している。このチムニの煙突効果により冷却水の自然循環力が高められるのである。一般に、沸騰水型原子炉の圧力では液体の水の密度は蒸気の密度に比べて２０倍以上大きい。このため、自然循環型沸騰水型原子炉では、チムニの設置により炉心上部の二相流状態の部分を高さ方向に長くとれば液体の水と、二相流状態の水との密度差による静水頭差を駆動力として、ＲＰＶ内で冷却材である水を、炉心を通して再循環させることが可能である。しかしながら、ＲＰＶ内で冷却水領域に設置される気水分離器は冷却材を自然循環させる際に抵抗要素となるので、気水分離器を削除できれば自然循環型沸騰水型原子炉における冷却水の自然循環特性を大きく改善できる。このために、重力による気水分離機構を用いて気水分離器を削除する自然循環型沸騰水型原子炉も提案されている。気水分離器の削除によって、自然循環特性の改善だけでなく、ＲＰＶの高さを低減できる。したがって、自然循環型沸騰水型原子炉をコンパクト化することができる。   In particular, a natural circulation boiling water reactor does not include a recirculation pump that forcibly circulates cooling water, and supplies cooling water to the core by natural circulation. In order to increase the natural circulation power of cooling water, the natural circulation boiling water reactor has a cylindrical chimney disposed above the core. This chimney chimney effect enhances the natural circulation of cooling water. In general, at the pressure of a boiling water reactor, the density of liquid water is 20 times or more larger than the density of steam. For this reason, in natural circulation boiling water reactors, if the length of the two-phase flow state at the top of the core is lengthened in the height direction by installing chimney, the difference in density between the liquid water and the water in the two-phase flow state It is possible to recirculate water, which is a coolant in the RPV, through the core using the hydrostatic head difference as a driving force. However, since the steam separator installed in the cooling water region in the RPV becomes a resistance element when the coolant is naturally circulated, if the steam separator is removed, the cooling water in the natural circulation boiling water reactor can be removed. Natural circulation characteristics can be greatly improved. For this purpose, a natural circulation boiling water reactor has been proposed in which the steam separator is removed using a gravity steam separator. The elimination of the steam separator can not only improve the natural circulation characteristics but also reduce the height of the RPV. Therefore, the natural circulation boiling water reactor can be made compact.

自然循環型沸騰水型原子炉における気水分離について、以下に示す技術が提案されている。   The following technologies have been proposed for air-water separation in a natural circulation boiling water reactor.

特開昭５９−１００８９４号公報は、自然循環型沸騰水型原子炉において、炉心を取り囲む炉心シュラウド上端に循環力促進装置を設けている。この循環力促進装置は、円筒容器の内面に複数の螺旋状の翼を有している。炉心から上昇した二相流は、循環力促進装置の円筒容器内に流入し、それらの翼によりに旋回力が与えられる。旋回する二相流に含まれる蒸気はＲＰＶの横断面内において中央部に集められ、その二相流に含まれて分離された冷却水は、円筒容器の上端から、ＲＰＶと炉心シュラウドの間に形成されるダウンカマー内に導かれる。   In Japanese Patent Laid-Open No. 59-100954, in a natural circulation boiling water nuclear reactor, a circulation force promoting device is provided at the upper end of a core shroud surrounding the core. This circulating force promoting device has a plurality of spiral blades on the inner surface of a cylindrical container. The two-phase flow that has risen from the core flows into the cylindrical container of the circulation force promoting device, and a swirling force is given by these blades. The steam contained in the swirling two-phase flow is collected at the center in the cross section of the RPV, and the cooling water separated and contained in the two-phase flow passes between the RPV and the core shroud from the upper end of the cylindrical vessel. Guided into the downcomer to be formed.

特開平３−９５４９６号公報は、自然循環型沸騰水型原子炉のＲＰＶ内で炉心上方に設けたチムニと蒸気乾燥器の間に、複数の増設立ち管を設置している。増設立ち管は、側壁に多数の開口が形成された環状部材の外面に旋回力を与える複数の羽根を設けている。環状部材内を上昇する気液二相流の流れが、各開口より外側に流出してそれらの羽根により旋回力が付与される。旋回した二相流がＲＰＶの内面に衝突することによって蒸気と水が分離される。   In Japanese Patent Laid-Open No. 3-95496, a plurality of additional standing pipes are installed between the chimney provided above the core in the RPV of the natural circulation boiling water reactor and the steam dryer. The additional standpipe is provided with a plurality of blades for applying a turning force to the outer surface of the annular member having a large number of openings formed in the side walls. The flow of the gas-liquid two-phase flow that rises in the annular member flows out of each opening, and a turning force is applied by these blades. Steam and water are separated by the swirling two-phase flow colliding with the inner surface of the RPV.

特開平１−１９７６９６号公報に記載された自然循環型沸騰水型原子炉は、ＲＰＶとシュラウドの間に形成されたダウンカマー内に、シュラウドを取囲む環状のバッフルを配置し、バッフルの下端部に気泡案内板を設置している。シュラウド内を上昇した気液二相流は、シュラウドの上端上方からバッフルとシュラウドの間に形成される環状流路に流入する。気泡案内板の下方では流路断面積が増大して流速が低下するため、蒸気の気泡は、気泡案内板下方のよどみ域に達し、バッフルとＲＰＶの間の気泡抜き通路を上昇する。   In a natural circulation boiling water reactor described in Japanese Patent Laid-Open No. 1-197696, an annular baffle surrounding a shroud is disposed in a downcomer formed between an RPV and a shroud, and a lower end portion of the baffle. The bubble guide plate is installed in The gas-liquid two-phase flow that has risen in the shroud flows into the annular flow path formed between the baffle and the shroud from above the upper end of the shroud. Since the flow path cross-sectional area increases below the bubble guide plate and the flow velocity decreases, the vapor bubbles reach the stagnation region below the bubble guide plate and ascend the bubble extraction passage between the baffle and the RPV.

特開平２−７８９９６号公報に記載された自然循環型沸騰水型原子炉は、炉心上方に配置したシュラウドの上端部でＲＰＶ側にバッフルが設けられている。バッフルとＲＰＶの間の領域は気泡抜き流路に連絡されている。シュラウド内を上昇した気液二相流は、シュラウド上端より上方から、ＲＰＶとシュラウドの間に形成されるダウンカマー内に流入する。ダウンカマー内に流下する蒸気の気泡は、バッフル下部に集まり、気泡抜き流路より上方に排出される。   In the natural circulation boiling water reactor described in Japanese Patent Laid-Open No. 2-78996, a baffle is provided on the RPV side at the upper end portion of the shroud disposed above the core. The area between the baffle and the RPV is connected to the bubble removal channel. The gas-liquid two-phase flow rising in the shroud flows into the downcomer formed between the RPV and the shroud from above the upper end of the shroud. Vapor bubbles flowing down into the downcomer gather at the bottom of the baffle and are discharged above the bubble vent channel.

特開昭５９−１００８９４号公報JP 59-100954 A 特開平３−９５４９６号公報JP-A-3-95496 特開平１−１９７６９６号公報JP-A-1-197696 特開平２−７８９９６号公報JP-A-2-78996

自然循環型沸騰水型原子炉において、気水分離器を取り除いて重力による気水分離機構を用いる場合、ダウンカマーに混入する蒸気の割合（以下、キャリーアンダーという）が増加する可能性がある。キャリーアンダーの増加は、ダウンカマー内の冷却水の平均密度を低下させ、冷却水の自然循環力が低減する。これにより、炉心に供給される冷却水量が減少し、炉心内の燃料棒の除熱性能等の低下を招く可能性がある。このため、キャリーアンダーはできるだけ少ない方が良い。また、ダウンカマー内で給水スパージャから供給された温度が飽和温度より低い給水と飽和温度の再循環水が合流する。冷却水の強制循環機構を備えていない自然循環型沸騰水型原子炉では、給水と再循環水の混合が促進されず、炉心入口までそれらが完全に混合されない可能性がある。この場合、炉心に装荷されている各燃料集合体に流入する冷却水の温度が均一化されなくなる可能性がある。このため、炉心の熱的余裕にこのことによる追加の設計余裕が必要になる可能性がある。   In a natural circulation boiling water reactor, when the steam separator is removed and the steam / water separation mechanism using gravity is used, the proportion of steam mixed in the downcomer (hereinafter referred to as carry-under) may increase. The increase in carry-under reduces the average density of the cooling water in the downcomer and reduces the natural circulation force of the cooling water. As a result, the amount of cooling water supplied to the core decreases, and there is a possibility that the heat removal performance of the fuel rods in the core will be reduced. For this reason, it is better to have as little carry-under as possible. In addition, the water supplied from the water supply sparger in the downcomer is supplied with water having a temperature lower than the saturation temperature and the recirculated water having the saturation temperature. In natural circulation boiling water reactors that do not have a forced circulation mechanism of cooling water, mixing of feed water and recirculated water is not promoted, and they may not be completely mixed up to the core inlet. In this case, there is a possibility that the temperature of the cooling water flowing into each fuel assembly loaded in the core will not be made uniform. This may require additional design margin for the thermal margin of the core.

なお、特開昭５９−１００８９４号公報は、円筒容器の内面に複数の螺旋状の翼を有して炉心より上方に配置された循環力促進装置によって冷却水と蒸気を分離しているが、十分な気水分離が行われず、旋回する冷却水に同伴してダウンカマー内に流入する蒸気が多くなる。これは、二相流を複数の翼によって水平方向に旋回させるからである。特開平３−９５４９６号公報は、環状部材の外面に設けた複数の羽根によって水平方向で二相流に旋回力を与え、この二相をＲＰＶ内面に衝突させて気水分離を行っている。このような気水分離では、ダウンカマー内の下降流に多くの蒸気が混入する可能性がある。また、特開昭５９−１００８９４号公報及び特開平３−９５４９６号公報では、ダウンカマー内を下降する冷却水と給水の混合が促進されない。   In JP-A-59-100894, cooling water and steam are separated by a circulation force promoting device having a plurality of spiral blades on the inner surface of a cylindrical container and disposed above the core. Sufficient air-water separation is not performed, and more steam flows into the downcomer accompanying the swirling cooling water. This is because the two-phase flow is swung horizontally by a plurality of blades. In Japanese Patent Laid-Open No. 3-95496, a plurality of blades provided on the outer surface of an annular member gives a turning force to a two-phase flow in the horizontal direction, and the two phases collide with the inner surface of the RPV to perform air-water separation. In such air-water separation, a large amount of steam may be mixed in the downward flow in the downcomer. Further, in Japanese Patent Application Laid-Open No. 59-100954 and Japanese Patent Application Laid-Open No. 3-95496, mixing of the cooling water and the feed water that descends in the downcomer is not promoted.

特開平１−１９７６９６号公報及び特開平２−７８９９６号公報は、共に、炉心シュラウドとＲＰＶの間にバッフルを配置し、ダウンカマー内に淀み水領域を作って、キャリーアンダーでダウンかマーに入り込んだ蒸気の気泡を分離している。しかしながら、これらの公知例では、給水と再循環水の混合が促進されない。   In both JP-A-1-197696 and JP-A-2-78996, a baffle is disposed between the core shroud and the RPV, a stagnation water region is formed in the downcomer, and the carry-under causes the down or the mar to enter. The vapor bubbles are separated. However, in these known examples, mixing of feed water and recirculated water is not promoted.

本発明の目的は、気水分離性能をさらに向上でき、かつ原子炉容器内での給水と再循環水の混合をより促進できる自然循環型沸騰水型原子炉を提供することにある。   An object of the present invention is to provide a natural circulation boiling water reactor that can further improve the air-water separation performance and can further promote the mixing of feed water and recirculated water in the reactor vessel.

上記した目的を達成する本発明の特徴は、自然循環型沸騰水型原子炉において、原子炉容器とチムニ及びシュラウドの間に形成された環状通路内に配置され、チムニから環状通路に導かれる冷却水を下方に向かって原子炉容器の周方向に旋回させる旋回流発生装置を備えたことにある。   A feature of the present invention that achieves the above-described object is that in a natural circulation boiling water reactor, cooling is arranged in an annular passage formed between the reactor vessel and the chimney and the shroud, and is led from the chimney to the annular passage. A swirl flow generating device for swirling water downward in the circumferential direction of the reactor vessel is provided.

環状通路内に旋回流発生装置を配置することによって、冷却水を環状通路内で下方に向かって原子炉容器の周方向に旋回させることができる。このような下方に向かう旋回流の発生によって、旋回流に含まれる蒸気の気泡の流れ方向と重力が作用する方向が異なるため、浮力によるその気泡の上昇力が大きくなる。このため、環状通路内に入り込んだ蒸気の気泡が、原子炉容器内に形成される冷却水の水面よりも上方に到達しやすくなる。すなわち、環状通路内を流下する冷却水に含まれた蒸気の分離効率が向上し、自然循環型沸騰水型原子炉での気水分離性能がさらに向上する。また、そのような旋回流の発生により、環状通路内での温度が異なる冷却水と給水の混合が促進され、炉心に供給される冷却水の温度がより均一化される。   By disposing the swirl flow generator in the annular passage, the cooling water can be swung downward in the circumferential direction of the reactor vessel in the annular passage. Due to the generation of the downward swirling flow, the flow direction of the bubbles of the vapor contained in the swirling flow is different from the direction in which the gravity acts, so that the rising force of the bubbles due to buoyancy increases. For this reason, the bubble of the vapor | steam which entered in the cyclic | annular channel | path becomes easy to reach | attain above the water surface of the cooling water formed in a nuclear reactor vessel. That is, the separation efficiency of steam contained in the cooling water flowing down in the annular passage is improved, and the steam-water separation performance in the natural circulation boiling water reactor is further improved. In addition, the generation of such a swirling flow promotes mixing of cooling water and feed water having different temperatures in the annular passage, and makes the temperature of the cooling water supplied to the core more uniform.

本発明によれば、シュラウドを取り囲んで形成された環状通路を流下する冷却水に含まれる蒸気の割合をさらに低減でき、その環状通路内での冷却水と給水の混合を促進することができる。   ADVANTAGE OF THE INVENTION According to this invention, the ratio of the vapor | steam contained in the cooling water which flows down through the annular channel | path formed surrounding the shroud can further be reduced, and mixing of the cooling water and feed water in the annular channel | channel can be accelerated | stimulated.

本発明の実施例を、以下に説明する。   Examples of the present invention will be described below.

本発明の好適な一実施例である実施例1の自然循環型沸騰水型原子炉を、図１〜図４を用いて以下に説明する。   A natural circulation boiling water reactor according to embodiment 1, which is a preferred embodiment of the present invention, will be described below with reference to FIGS.

本実施例の自然循環型沸騰水型原子炉２０は、ＲＰＶ２内に、炉心１、炉心シュラウド３、チムニ４、蒸気乾燥器５及び旋回流発生装置９を配置している。円筒である炉心シュラウド３は複数の燃料集合体（図示せず）が装荷されている炉心１を取り囲んでいる。チムニ４は炉心１の上方に位置し、炉心シュラウド３の上端部に設置される。炉心シュラウド３は、その下端に取り付けられた、支持部材である複数のシュラウドレグ（図示せず）によってＲＰＶ２の底部に設置されている。それらのシュラウドレグは、ＲＰＶ２の周方向において間隔をおいて配置される。チムニ４は、円筒部材２２内に格子部材２３を設けて構成されている（図３参照）。このチムニ４は、ＲＰＶ２の軸方向に伸びており、格子部材２３によって画定される横断面が正方形である多数の冷却水通路２４を形成している。蒸気乾燥器５は、チムニ４の上方に配置され、ＲＰＶ２に取り付けられる。チムニ４と蒸気乾燥器５の間には、重力により気水分離を行う空間（気水分離空間）２１が形成されている。ダウンカマー（環状通路）８は、ＲＰＶ２と炉心シュラウド３及びチムニ４の間に形成される。給水スパージャ６がチムニ４の周囲でダウンカマー８内に配置される。給水スパージャ６は、リングヘッダー２５に複数のノズル２６を設けている（図２参照）。炉心１の下方に位置する下部プレナム１２内に、複数の制御棒案内管１３が配置されている。燃料集合体間に挿入される制御棒（図示せず）が制御棒案内管１３内に配置される。   In the natural circulation boiling water reactor 20 of the present embodiment, a core 1, a core shroud 3, a chimney 4, a steam dryer 5 and a swirling flow generator 9 are arranged in an RPV 2. A cylindrical core shroud 3 surrounds the core 1 loaded with a plurality of fuel assemblies (not shown). The chimney 4 is located above the core 1 and is installed at the upper end of the core shroud 3. The core shroud 3 is installed at the bottom of the RPV 2 by a plurality of shroud legs (not shown) as support members attached to the lower end thereof. These shroud legs are spaced apart in the circumferential direction of the RPV 2. The chimney 4 is configured by providing a lattice member 23 in a cylindrical member 22 (see FIG. 3). The chimney 4 extends in the axial direction of the RPV 2 and forms a large number of cooling water passages 24 having a square cross section defined by the lattice members 23. The steam dryer 5 is disposed above the chimney 4 and attached to the RPV 2. Between the chimney 4 and the steam dryer 5, a space (air / water separation space) 21 that performs air / water separation by gravity is formed. A downcomer (annular passage) 8 is formed between the RPV 2 and the core shroud 3 and chimney 4. A water supply sparger 6 is disposed in the downcomer 8 around the chimney 4. The water supply sparger 6 is provided with a plurality of nozzles 26 in the ring header 25 (see FIG. 2). A plurality of control rod guide tubes 13 are arranged in a lower plenum 12 located below the core 1. A control rod (not shown) inserted between the fuel assemblies is disposed in the control rod guide tube 13.

旋回流発生装置９は、複数（具体的には８枚）の羽根部材３４を有し、ダウンカマー８内に配置される（図３参照）。それらの羽根部材３４は、ダウンカマー８内に配置されてチムニ４の円筒部材２２の外面に同じ高さで取り付けられ、ＲＰＶ２の周方向に所定の間隔を置いて配置される。これらの羽根部材３４は、炉心１内の燃料集合体の交換時にチムニ４をＲＰＶ２から取り出す必要があるので、ＲＰＶ２の内面に接触していない。各羽根部材３４は、図４に示すように、ＲＰＶ２の周方向において同じ方向に向かって傾斜している。図４は、チムニ４の円筒部材２２の一周の１／４で、羽根部材３４が設置された部分の外面を展開して示している。各羽根部材３４のその周方向における一端は、羽根部材３４の周方向における他端よりも高い位置にある。すなわち、各羽根部材３４は図４において向かって左下がりになるように傾斜している。羽根部材３４はＲＰＶ２の内面に取り付けることも可能である。旋回流発生装置９は、給水スパージャ６よりも上方でダウンカマー８内に配置するとよい。
しかしながら、ＲＰＶ２は圧力バウンダリであり、羽根部材３４を溶接等でＲＰＶ２取り付ける場合にはＲＰＶ２の健全性を損ねる可能性があるので、一般的にはチムニ４の外面に付けた方がよい。 The swirling flow generating device 9 has a plurality of (specifically, eight) blade members 34 and is disposed in the downcomer 8 (see FIG. 3). These blade members 34 are disposed in the downcomer 8 and are attached to the outer surface of the cylindrical member 22 of the chimney 4 at the same height, and are disposed at a predetermined interval in the circumferential direction of the RPV 2. These blade members 34 are not in contact with the inner surface of the RPV 2 because the chimney 4 needs to be taken out of the RPV 2 when the fuel assembly in the core 1 is replaced. As shown in FIG. 4, each blade member 34 is inclined in the same direction in the circumferential direction of the RPV 2. FIG. 4 is a developed view of the outer surface of the portion where the blade member 34 is installed in 1/4 of the circumference of the cylindrical member 22 of the chimney 4. One end of each blade member 34 in the circumferential direction is higher than the other end of the blade member 34 in the circumferential direction. That is, each blade member 34 is inclined so as to be lowered to the left in FIG. The blade member 34 can be attached to the inner surface of the RPV 2. The swirling flow generating device 9 may be disposed in the downcomer 8 above the water supply sparger 6.
However, RPV2 is a pressure boundary, and when the blade member 34 is attached to the RPV2 by welding or the like, the soundness of the RPV2 may be impaired.

下部プレナム１２から炉心１内に供給された冷却水は、炉心１に装荷された燃料集合体内の核燃料物質の核***によって加熱され、一部が蒸気となる。冷却水と蒸気を含む二相流は、炉心１内を上昇し、チムニ４に形成された各冷却水通路２４内をさらに上昇して気水分離空間２１内に達する。気水分離空間２１内で重力により冷却水から分離された蒸気は、蒸気乾燥器５において水分をさらに除去される。蒸気乾燥器５から排出された蒸気は、ＲＰＶ２に接続された主蒸気配管７に排出され、タービン（図示せず）に供給される。このタービンを回転させてタービンから排出された蒸気は、復水器（図示せず）で凝縮されて水となる。この水は、給水として、給水ポンプ（図示せず）で昇圧され、給水配管２７により給水スパージャ６のリングヘッダー２５内に導かれる。給水は多数のノズル２６からＲＰＶ２内、すなわち、ダウンカマー８内に供給される。この給水の温度は、ＲＰＶ２内の冷却水の飽和温度よりも低い。   The cooling water supplied from the lower plenum 12 into the core 1 is heated by the nuclear fission of the nuclear fuel material in the fuel assembly loaded in the core 1 and partly becomes steam. The two-phase flow including the cooling water and the steam rises in the core 1 and further rises in each cooling water passage 24 formed in the chimney 4 and reaches the steam-water separation space 21. The steam separated from the cooling water by gravity in the steam-water separation space 21 is further removed of moisture in the steam dryer 5. The steam discharged from the steam dryer 5 is discharged to a main steam pipe 7 connected to the RPV 2 and supplied to a turbine (not shown). The steam discharged from the turbine by rotating this turbine is condensed by a condenser (not shown) to become water. This water is boosted by a feed pump (not shown) as feed water, and is led into the ring header 25 of the feed water sparger 6 by the feed water pipe 27. The water supply is supplied into the RPV 2 from the multiple nozzles 26, that is, into the downcomer 8. The temperature of this water supply is lower than the saturation temperature of the cooling water in RPV2.

自然循環型沸騰水型原子炉２０の運転時では、冷却水の水面が気水分離空間２１内において蒸気乾燥器５付近に形成されている。気水分離空間２１内で蒸気を分離された冷却水は、気水分離空間２１からダウンカマー８内に流入する。気水分離空間２１で蒸気が完全に分離されないため、気水分離空間２１からダウンカマー８内に流入した冷却水（再循環水）は、蒸気を含んでいる。この蒸気を含んだ冷却水は、旋回流発生装置９の羽根部材３４相互間に形成される冷却水通路２８内に導かれ、羽根部材３４の傾斜角度で下方に向かう旋回流となる。詳細は後述するが、蒸気は、浮力の作用によって旋回流から分離され、ＲＰＶ２内に形成される冷却水の水面に向かって上昇する。このように、ダウンカマー８内に流入した冷却水に含まれる蒸気が分離される。旋回流発生装置９によって旋回流となった冷却水は、チムニ４及び炉心シュラウド３の周囲を一方向に旋回しながらダウンカマー８内を下降する。この旋回している、飽和温度の冷却水に、給水スパージャ６のノズル２６から供給された、その冷却水よりも温度が低い給水が混入される。給水を混入した冷却水は、シュラウドレグ相互間を通過して下部プレナム１２に到達し、炉心１に供給される。   During the operation of the natural circulation boiling water reactor 20, the water surface of the cooling water is formed in the vicinity of the steam dryer 5 in the steam-water separation space 21. The cooling water from which the steam is separated in the steam-water separation space 21 flows into the downcomer 8 from the steam-water separation space 21. Since the steam is not completely separated in the steam / water separation space 21, the cooling water (recirculated water) that has flowed into the downcomer 8 from the steam / water separation space 21 contains steam. The cooling water containing the steam is guided into the cooling water passage 28 formed between the blade members 34 of the swirl flow generator 9, and becomes a swirl flow directed downward at an inclination angle of the blade members 34. Although details will be described later, the steam is separated from the swirling flow by the action of buoyancy, and rises toward the surface of the cooling water formed in the RPV 2. In this way, the steam contained in the cooling water flowing into the downcomer 8 is separated. The cooling water converted into a swirl flow by the swirl flow generator 9 descends in the downcomer 8 while swirling around the chimney 4 and the core shroud 3 in one direction. The swirling cooling water having the saturation temperature is mixed with the feed water supplied from the nozzle 26 of the feed water sparger 6 and having a temperature lower than that of the cooling water. The cooling water mixed with the feed water passes between the shroud legs and reaches the lower plenum 12 and is supplied to the core 1.

旋回流発生装置９の設置によって、ダウンカマー８内に流入した冷却水から蒸気が分離される理由を以下に説明する。   The reason why the steam is separated from the cooling water flowing into the downcomer 8 by the installation of the swirling flow generator 9 will be described below.

まず、旋回流発生装置９が設置されていない状態でのダウンカマー８内の冷却水の流れについて述べる。ダウンカマー８内に流れ込んだ蒸気は、冷却水中で気泡として存在する。ダウンカマー８内に流れ込んだ冷却水がほぼ鉛直方向で下向きに流れる。この場合は、図５（Ａ）に示すように、ダウンカマー８内の冷却水の流れ（矢印３０）が鉛直方向において下向きとなり、重量の向きと冷却水の流れの向きが同じであることから蒸気の気泡の形状は鉛直軸を中心にほぼ対称な形になる。蒸気の気泡はダウンカマー８内を流下する冷却水よりも密度が小さいので、その気泡に鉛直方向で上向きに浮力（矢印３１）が働く。この浮力はダウンカマー８に蒸気が流れ込むのを抑制する効果として働くが、ダウンカマー８内の冷却水の流れが鉛直方向において下向きで、浮力が鉛直方向において上向きである場合、その気泡２９Ａの形状は鉛直軸方向と直交する方向で細長くなる（図５（Ａ）参照）。冷却水の流動力及び重力が、共に、そのような細長い気泡２９Ａに同じ方向に作用することになる。したがって、ダウンカマー８内における冷却水の下降流（鉛直方向の流れ）への蒸気の巻き込みが気泡２９Ａに作用する上方に向かう浮力によって抑制される度合いが小くなる。   First, the flow of the cooling water in the downcomer 8 when the swirl flow generator 9 is not installed will be described. The steam flowing into the downcomer 8 exists as bubbles in the cooling water. The cooling water that has flowed into the downcomer 8 flows downward in a substantially vertical direction. In this case, as shown in FIG. 5A, the flow of the cooling water (down arrow 30) in the downcomer 8 is downward in the vertical direction, and the direction of weight and the direction of the flow of cooling water are the same. The shape of the vapor bubbles is almost symmetrical about the vertical axis. Since the bubbles of vapor have a lower density than the cooling water flowing down in the downcomer 8, buoyancy (arrow 31) acts on the bubbles in the vertical direction. This buoyancy works as an effect of suppressing the flow of steam into the downcomer 8, but when the flow of the cooling water in the downcommer 8 is downward in the vertical direction and the buoyancy is upward in the vertical direction, the shape of the bubble 29A Is elongated in a direction perpendicular to the vertical axis direction (see FIG. 5A). Both the flow force and the gravity of the cooling water act on the elongated bubbles 29A in the same direction. Therefore, the degree to which the entrainment of steam into the downward flow (vertical flow) of the cooling water in the downcomer 8 is suppressed by the upward buoyancy acting on the bubbles 29A becomes small.

一方、複数の羽根部材３４を有する旋回流発生装置９の設置によって、冷却水は、ダウンカマー８内でＲＰＶ２の周方向に速度を与えられ、チムニ４及び炉心シュラウド３の周囲を回るように下方に向かって旋回する。この旋回流の発生により、図５（Ｂ）に示すように、その冷却水に含まれる蒸気の気泡２９Ｂの流れ（矢印３２）の向きが重力（矢印３３）の向きと異なる方向となるため、その蒸気の気泡２９Ｂの形状が、鉛直方向において非対称な形状となる。このような形状の気泡２９Ｂに、異なる方向に向かう冷却水の流動力及び重力が作用するため、浮力（矢印３１）の作用により発生する、気泡２９Ｂの上昇力は、上記した気泡２９Ａの上昇力よりも大きくなる。この上昇力の違いは、気泡の形状の違いと共に、冷却水の流動力及び重力が作用する方向が異なっているか同じであるかにも起因している。本実施例は、上記したように気泡２９Ｂの上昇力が大きくなるため、ダウンカマー８内での気泡２９Ｂの分離及び合体が促進され、ダウンカマー８から冷却水の水面の上方に到達する、分離された蒸気（気泡）の量が増大する。自然循環型沸騰水型原子炉２０は、羽根部材３４によりダウンカマー８内において下向きで周方向に流れる冷却水の旋回流を発生させることによって、気水分離空間２１からダウンカマー８内に流入した冷却水に含まれる蒸気の分離性能をさらに向上させることができる。したがって、ダウンカマー８から下部プレナム１２に導かれる流体の平均密度を大きくすることができ、炉心１に供給される冷却水流量を増加させることができる。炉心１の除熱性能等が向上するため、自然循環型沸騰水型原子炉２０は、出力を増大でき、経済性が向上する。   On the other hand, due to the installation of the swirl flow generator 9 having the plurality of blade members 34, the cooling water is given a speed in the circumferential direction of the RPV 2 in the downcomer 8, and moves downward around the chimney 4 and the core shroud 3. Turn towards. Due to the generation of this swirl flow, as shown in FIG. 5 (B), the direction of the flow (arrow 32) of the bubbles 29B of the steam contained in the cooling water is different from the direction of gravity (arrow 33). The shape of the vapor bubble 29B is asymmetric in the vertical direction. Since the flow force and gravity of the cooling water directed in different directions act on the bubbles 29B having such a shape, the upward force of the bubbles 29B generated by the action of the buoyancy (arrow 31) is the upward force of the bubbles 29A. Bigger than. This difference in ascending force is caused by whether the flow force of the cooling water and the direction in which gravity acts are different or the same as the difference in the shape of the bubbles. In the present embodiment, as described above, since the rising force of the bubbles 29B is increased, the separation and coalescence of the bubbles 29B in the downcomer 8 are promoted, and the separation that reaches the cooling water level from the downcomer 8 is achieved. The amount of vapor (bubbles) generated increases. The natural circulation boiling water nuclear reactor 20 flows into the downcommer 8 from the steam-water separation space 21 by generating a swirling flow of cooling water flowing downward and circumferentially in the downcomer 8 by the blade member 34. The separation performance of the steam contained in the cooling water can be further improved. Therefore, the average density of the fluid guided from the downcomer 8 to the lower plenum 12 can be increased, and the flow rate of the cooling water supplied to the core 1 can be increased. Since the heat removal performance and the like of the core 1 are improved, the natural circulation boiling water reactor 20 can increase the output and improve the economy.

気水分離空間２１からダウンカマー８内に流入する飽和温度の冷却水と給水スパージャ６から供給される、飽和温度よりも低い給水の温度差は、一般に７０〜９０℃である。ダウンカマー８内に旋回流発生装置９が設置されていない場合には、ダウンカマー８内を流下する、飽和温度の冷却水と給水が、前述したように、完全に混合されない可能性がある。これは以下の理由による。温度の低い給水はダウンカマー８内を下降する冷却水よりも密度が大きい。密度の大きな給水が、重力の作用により、鉛直方向で下向きの流速が加速されてダウンカマー８内を鉛直方向で下降する。このため、給水と飽和温度の冷却水の混合がダウンカマー８内で十分に行われない。これは、炉心１の熱的余裕を減少させることになり、原子炉の熱出力を低下させなければならなくなる。   The temperature difference between the cooling water having the saturation temperature flowing into the downcomer 8 from the steam separation space 21 and the feed water supplied from the feed water sparger 6 and lower than the saturation temperature is generally 70 to 90 ° C. When the swirl flow generator 9 is not installed in the downcomer 8, there is a possibility that the cooling water and the feed water at the saturation temperature flowing down in the downcomer 8 are not completely mixed as described above. This is due to the following reason. The low temperature water supply has a higher density than the cooling water descending the downcomer 8. Due to the action of gravity, the water supply having a high density is accelerated in the downward direction in the vertical direction and descends in the downcomer 8 in the vertical direction. For this reason, the water supply and the cooling water at the saturation temperature are not sufficiently mixed in the downcomer 8. This reduces the thermal margin of the core 1, and the thermal output of the reactor must be reduced.

これに対して、本実施例は、旋回流発生装置９を設置しているので、上記したように、ダウンカマー８内において下向きで周方向に流れる冷却水の旋回流が発生する。この旋回流の発生によって、飽和温度の冷却水と温度の低い給水の混合がダウンカマー８内で促進される。周方向の速度成分が加わることにより、給水の流れが、重力の向きと異なる方向（重力の向きと交差する方向）を向くことによっても、それらの混合が促進される。このため、本実施例では、温度の低い給水と飽和温度の冷却水がダウンカマー８内でほぼ完全に混合される。また、下部プレナム１２に導かれた後においても、それらの混合が周方向の速度成分があることにより行われる。したがって、本実施例では、炉心１の入口において、給水とダウンカマー８を流下する冷却水（再循環水）は、完全に混合されている。本実施例は、炉心１の熱的余裕が増大し、原子炉の熱出力の低下を回避することができる。原子炉の経済性が向上する。   On the other hand, since the swirl | vortex flow generator 9 is installed in the present Example, as above-mentioned, the swirl | vortex flow of the cooling water which flows in the down direction in the downcomer 8 and a circumferential direction generate | occur | produces. By the generation of the swirling flow, mixing of the cooling water having the saturation temperature and the low-temperature feed water is promoted in the downcomer 8. By adding the velocity component in the circumferential direction, mixing of the water supply is also promoted by the flow of the water supply being directed in a direction different from the direction of gravity (a direction intersecting the direction of gravity). For this reason, in this embodiment, the feed water having a low temperature and the cooling water having a saturation temperature are almost completely mixed in the downcomer 8. Further, even after being guided to the lower plenum 12, the mixing is performed due to the presence of the velocity component in the circumferential direction. Therefore, in this embodiment, the feed water and the cooling water (recirculated water) flowing down the downcomer 8 are completely mixed at the inlet of the core 1. In this embodiment, the thermal margin of the core 1 is increased, and a decrease in the thermal output of the nuclear reactor can be avoided. The economic efficiency of the nuclear reactor is improved.

旋回流発生装置９をダウンカマー８内で給水スパージャ６より上方に配置することによって、以下に示す効果を得ることができる。旋回流発生装置９を給水スパージャ６よりも上方に配置した場合には、旋回流発生装置９を給水スパージャ６よりも下方に配置した場合に比べて、ダウンカマー８内を流下する再循環水と給水の混合促進距離（鉛直方向）が大きくなるので、再循環水と給水と再循環水の混合促進効果が増大する。旋回流発生装置９を給水スパージャ６よりも上方に配置した場合には、再循環水に含まれている蒸気の気泡は、温度の低い給水との接触によって凝縮することが避けられる。このため、その気泡の浮力が低減されず、再循環水から分離されて冷却水の水面より上方に到達する蒸気の量が増大する。給水スパージャ６から吐出された給水は、温度が飽和温度である再循環水より低く密度が大きいので、重力の作用により再循環水に比べて相対的に加速される度合いが大きい。本実施例は、旋回流発生装置９を給水スパージャ６よりも上方に配置することによって、給水の加速力があまり大きくならない状態、すなわち給水と再循環水の速度差が小さいうちに給水と再循環水を旋回させて混合することができる。したがって、給水と再循環水の混合がより促進される。   By arranging the swirling flow generating device 9 above the water supply sparger 6 in the downcomer 8, the following effects can be obtained. When the swirling flow generating device 9 is disposed above the water supply sparger 6, compared with the case where the swirling flow generating device 9 is disposed below the water supply sparger 6, the recirculated water flowing down in the downcommer 8 Since the mixing promotion distance (vertical direction) of water supply becomes large, the mixing promotion effect of recirculation water, water supply, and recirculation water increases. When the swirl flow generator 9 is disposed above the feed water sparger 6, it is possible to avoid condensing the bubbles of steam contained in the recirculated water due to contact with the feed water having a low temperature. For this reason, the buoyancy of the bubbles is not reduced, and the amount of steam separated from the recirculated water and reaching above the water surface of the cooling water increases. Since the feed water discharged from the feed water sparger 6 is lower in density and higher in density than the recirculated water whose saturation temperature is the saturation temperature, the degree of relative acceleration is higher than that of the recirculated water due to the action of gravity. In this embodiment, the swirl flow generator 9 is arranged above the feed water sparger 6 so that the acceleration force of the feed water does not increase so much, that is, while the speed difference between the feed water and the recirculation water is small. The water can be swirled to mix. Therefore, mixing of water supply and recirculation water is promoted more.

本実施例は、旋回流発生装置９をダウンカマー８内で上部に配置しているため、分離された蒸気の気泡が冷却水の液面より上方に到達しやすくなる。   In this embodiment, the swirling flow generating device 9 is arranged in the upper part in the downcomer 8, so that the bubbles of the separated steam easily reach above the liquid level of the cooling water.

本実施例は、気水分離空間２１を形成してチムニ４の上方に気水分離器を設置していないので、ＲＰＶ２の高さを低くすることができ、自然循環型沸騰水型原子炉２０をコンパクト化することができる。   In the present embodiment, since the steam-water separation space 21 is formed and no steam-water separator is installed above the chimney 4, the height of the RPV 2 can be reduced, and the natural circulation boiling water reactor 20 Can be made compact.

旋回流発生装置９を構成する各羽根部材３４は、円筒部材２２及び炉心シュラウド３の外面に対して直角に設けることが望ましい。しかしながら、羽根部材３４を、ＲＰＶ２の半径方向におい円筒部材２２及び炉心シュラウド３の外面に対して傾斜させて設置することも可能である。   Each blade member 34 constituting the swirl flow generator 9 is preferably provided at right angles to the outer surface of the cylindrical member 22 and the core shroud 3. However, it is also possible to install the blade member 34 so as to be inclined with respect to the outer surface of the cylindrical member 22 and the core shroud 3 in the radial direction of the RPV 2.

本実施例において、旋回流発生装置９の替りに、図６に示す旋回流発生装置９Ａを用いてもよい。旋回流発生装置９Ａは、鉛直方向での断面形状が湾曲している８枚の羽根部材３４Ａを含んでいる。この旋回流発生装置９Ａは、羽根部材３４Ａの製造が面倒であるが、周方向の速度成分を滑らかに増大させることができ、旋回流発生装置９よりも圧力損失を低減させることができる。   In this embodiment, instead of the swirl flow generator 9, a swirl flow generator 9A shown in FIG. 6 may be used. The swirling flow generating device 9A includes eight blade members 34A having a curved cross-sectional shape in the vertical direction. Although the swirl flow generator 9A is troublesome to manufacture the blade member 34A, the speed component in the circumferential direction can be increased smoothly, and the pressure loss can be reduced as compared with the swirl flow generator 9.

旋回流発生装置としては、図７に示す旋回流発生装置９Ｂを用いることも可能である。旋回流発生装置９Ｂは、下流側に両面に傾斜面１７を形成して鉛直方向での肉厚を下流側端に向かって減少させている８枚の羽根部材３４Ｂを含んでいる。各羽根部材３４Ｂにおけるその肉厚の減少は徐々に行われる。この結果、ＲＰＶ２の周方向において隣り合う羽根部材３４Ｂ相互間に形成される冷却水通路２８の流路断面積は、傾斜面１７の形成によって、冷却水通路２８の途中から下流側に向かう程、広くなっている。傾斜面１７を有する旋回流発生装置９Ｂの採用により、羽根部材３４Ｂの下流側で渦の剥離等により流れが乱れる。このため、旋回流発生装置９Ｂは、旋回流発生装置９よりもダウンカマー８内における給水と冷却水の混合をさらに促進させることができる。また、旋回流発生装置９Ｂにおいて羽根部材３４Ｂの上流側の先端部の、鉛直方向の断面形状を、流線型にすることも可能である。先端部を流線型に形成することによって、先端部での渦の発生が低減されるため、ダウンカマー８の圧力損失を低減することができる。羽根部材３４，３４Ａも、上流側の先端部を流線型にしてもよい。   As the swirling flow generating device, a swirling flow generating device 9B shown in FIG. 7 can also be used. The swirl flow generating device 9B includes eight blade members 34B that are formed with inclined surfaces 17 on both sides on the downstream side to reduce the thickness in the vertical direction toward the downstream end. The thickness of each blade member 34B is gradually reduced. As a result, the flow passage cross-sectional area of the cooling water passage 28 formed between the blade members 34B adjacent to each other in the circumferential direction of the RPV 2 increases toward the downstream side from the middle of the cooling water passage 28 due to the formation of the inclined surface 17. It is getting wider. By employing the swirl flow generator 9B having the inclined surface 17, the flow is disturbed due to vortex separation or the like on the downstream side of the blade member 34B. For this reason, the swirl flow generator 9 </ b> B can further promote the mixing of the water supply and the cooling water in the downcomer 8 than the swirl flow generator 9. Further, in the swirling flow generating device 9B, the vertical cross-sectional shape of the tip portion on the upstream side of the blade member 34B can be made streamlined. By forming the tip portion in a streamline shape, the generation of vortex at the tip portion is reduced, so that the pressure loss of the downcomer 8 can be reduced. The blade members 34 and 34A may also be streamlined at the upstream end.

本発明の他の実施例である実施例２の自然循環型沸騰水型原子炉を、図８を用いて以下に説明する。本実施例の自然循環型沸騰水型原子炉２０Ａは、ＲＰＶ２内に気水分離器１５を設置している自然循環型沸騰水型原子炉に旋回流発生装置９を設置した構成を有する。旋回流発生装置９は、ダウンカマー８内に配置されてチムニ４の円筒部材２２の外面に設置されている。気水分離器１５は、チムニ４と蒸気乾燥器５の間に配置され、チムニ４の上端部に設置されている。換言すれば、自然循環型沸騰水型原子炉２０Ａは、自然循環型沸騰水型原子炉２０において、気水分離空間２１の替りに気水分離器１５を設けた構成を有する。本実施例においても、旋回流発生装置９の替りに前述の旋回流発生装置９Ａまたは旋回流発生装置９Ｂを用いてもよい。   A natural circulation boiling water reactor according to embodiment 2, which is another embodiment of the present invention, will be described below with reference to FIG. The natural circulation boiling water reactor 20A of the present embodiment has a configuration in which a swirl flow generator 9 is installed in a natural circulation boiling water reactor in which a steam separator 15 is installed in the RPV 2. The swirling flow generating device 9 is disposed in the downcomer 8 and is installed on the outer surface of the cylindrical member 22 of the chimney 4. The steam separator 15 is disposed between the chimney 4 and the steam dryer 5 and is installed at the upper end of the chimney 4. In other words, the natural circulation boiling water reactor 20 </ b> A has a configuration in which the steam / water separator 15 is provided in place of the steam / water separation space 21 in the natural circulation boiling water reactor 20. Also in this embodiment, instead of the swirl flow generator 9, the swirl flow generator 9A or the swirl flow generator 9B described above may be used.

本実施例は、気水分離器１５を備えた自然循環型沸騰水型原子炉２０Ａにおいて旋回流発生装置９を備えているので、旋回流発生装置９の前述の作用により、単に気水分離器を備えた自然循環型沸騰水型原子炉よりも、炉心１に導かれる蒸気の気泡の割合を低減することができる。本実施例は、実施例１の自然循環型沸騰水型原子炉２０に比べて炉心１に導かれる蒸気の気泡の割合を低減できる。本実施例は、ダウンカマー８内における冷却水と給水の混合を、実施例１と同様に促進させることができる。ただし、本実施例は、気水分離器１５を備えているため、ＲＰＶ２の高さが自然循環型沸騰水型原子炉２０のそれよりも高くなる。   In the present embodiment, the natural circulation boiling water reactor 20A provided with the steam separator 15 is provided with the swirling flow generating device 9, so that the swirling flow generating device 9 simply has the above function. The ratio of steam bubbles introduced to the core 1 can be reduced as compared with a natural circulation boiling water reactor equipped with This embodiment can reduce the ratio of steam bubbles introduced to the core 1 compared to the natural circulation boiling water reactor 20 of the first embodiment. In the present embodiment, the mixing of the cooling water and the supply water in the downcomer 8 can be promoted similarly to the first embodiment. However, since the present embodiment includes the steam-water separator 15, the height of the RPV 2 is higher than that of the natural circulation boiling water reactor 20.

上記した各旋回流発生装置のそれぞれの羽根部材は、チムニ４の円筒部材２２（または炉心シュラウド３）の外面に溶接にて取り付けられるが、ボルト等で取り付けることも可能である。ボルトを使用する場合には、ボルトの回り止めの措置を行う必要がある。羽根部材は、ダウンカマー８内で周方向に配置する枚数は８枚に限らない。   Each blade member of each of the swirl flow generators described above is attached to the outer surface of the cylindrical member 22 (or the core shroud 3) of the chimney 4 by welding, but may be attached with a bolt or the like. When using bolts, it is necessary to take measures to prevent the bolts from rotating. The number of blade members arranged in the circumferential direction in the downcomer 8 is not limited to eight.

本発明の好適な一実施例である実施例１の自然循環型沸騰水型原子炉の構成図である。BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the natural circulation type boiling water reactor of Example 1 which is one suitable Example of this invention. 図１に示す給水スパージャの局部斜視図である。It is a local perspective view of the water supply sparger shown in FIG. 図１のIII−III断面図である。FIG. 3 is a sectional view taken along line III-III in FIG. 1. 図１に示す旋回流発生装置のチムニの円筒部材への取り付け状態を示す円筒部材の周方向における１／４の展開図である。FIG. 3 is a developed view of a quarter of the cylindrical member in the circumferential direction showing a state in which the swirl flow generating device shown in FIG. ダウンカマー内を流下する蒸気の気泡の流れ方向、浮力及び重力が作用する方向を示す模式図であり、（Ａ）は従来の自然循環型沸騰水型原子炉のダウンカマー内での蒸気の気泡の流れ方向、浮力及び重力が作用する方向を示す説明図、（Ｂ）は図１に示す実施例におけるダウンカマー内での蒸気の気泡の流れ方向、浮力及び重力が作用する方向を示す説明図である。It is a schematic diagram which shows the flow direction of the bubble of the steam which flows down in the downcomer, the direction in which buoyancy and gravity act, (A) is the bubble of the steam in the downcomer of the conventional natural circulation type boiling water reactor Explanatory drawing which shows the direction where the flow direction, buoyancy, and gravity act of FIG. 1, (B) is explanatory drawing which shows the flow direction of the bubble bubble in the downcomer in the Example shown in FIG. 1, the direction where buoyancy, and gravity act It is. 旋回流発生装置の他の実施例の構成図である。It is a block diagram of the other Example of a swirling flow generator. 旋回流発生装置の他の実施例の構成図である。It is a block diagram of the other Example of a swirling flow generator. 本発明の他の実施例である実施例２の自然循環型沸騰水型原子炉の構成図である。It is a block diagram of the natural circulation type boiling water reactor of Example 2 which is another Example of this invention.

符号の説明Explanation of symbols

１…炉心、２…原子炉圧力容器、３…炉心シュラウド、４…チムニ、６…給水スパージャ、８…ダウンカマー、９，９Ａ，９Ｂ…旋回流発生装置、１５…気水分離器、１７…傾斜面、２０，２０Ａ…自然循環型沸騰水型原子炉、２２…円筒部材、２３…格子部材、２４，２８…冷却水通路、３４，３４Ａ，３４Ｂ…羽根部材。   DESCRIPTION OF SYMBOLS 1 ... Core, 2 ... Reactor pressure vessel, 3 ... Core shroud, 4 ... Chimney, 6 ... Feed water sparger, 8 ... Downcomer, 9, 9A, 9B ... Swirling flow generator, 15 ... Air-water separator, 17 ... Inclined surface, 20, 20A ... natural circulation type boiling water reactor, 22 ... cylindrical member, 23 ... lattice member, 24, 28 ... cooling water passage, 34, 34A, 34B ... blade member.

Claims (9)

炉心を内蔵する原子炉容器と、前記原子炉容器内に設置されて前記炉心を取り囲むシュラウドと、前記原子炉容器内で前記炉心の上方に配置されたチムニと、前記原子炉容器と前記チムニ及び前記シュラウドの間に形成された環状通路内に配置された給水スパージャと、前記環状通路内に配置され、前記チムニから前記環状通路に導かれる冷却水を下方に向かって前記原子炉容器の周方向に旋回させる旋回流発生装置とを備えたことを特徴とする自然循環型沸騰水型原子炉。   A reactor vessel containing a reactor core, a shroud installed in the reactor vessel and surrounding the reactor core, a chimney disposed above the core in the reactor vessel, the reactor vessel, the chimney, and A water supply sparger disposed in an annular passage formed between the shrouds, and a cooling water disposed in the annular passage and guided from the chimney to the annular passage downward in the circumferential direction of the reactor vessel A natural circulation type boiling water reactor characterized by comprising a swirl flow generator for swirling. 前記原子炉容器内に配置され、前記チムニよりも上方に位置している蒸気乾燥器を備え、前記チムニと前記蒸気乾燥器の間に気水分離空間を形成している請求項１に記載の自然循環型沸騰水型原子炉。   The steam dryer which is arrange | positioned in the said reactor vessel and is located above the said chimney is provided, The steam-water separation space is formed between the said chimney and the said steam dryer. Natural circulation boiling water reactor. 気水分離装置を前記チムニよりも上方で前記原子炉容器内に配置している請求項１に記載の自然循環型沸騰水型原子炉。   The natural circulation boiling water reactor according to claim 1, wherein a steam-water separator is disposed in the reactor vessel above the chimney. 前記旋回流発生装置は、前記周方向に間隔を置いて配置され、下方に向かって傾斜した複数の羽根部材を有している請求項１ないし請求項３のいずれか１項に記載の自然循環型沸騰水型原子炉。   The natural circulation according to any one of claims 1 to 3, wherein the swirling flow generating device includes a plurality of blade members that are arranged at intervals in the circumferential direction and are inclined downward. Type boiling water reactor. 前記複数の羽根部材が前記チムニの外面に取り付けられている請求項４に記載の自然循環型沸騰水型原子炉。   The natural circulation boiling water reactor according to claim 4, wherein the plurality of blade members are attached to an outer surface of the chimney. 前記羽根部材が湾曲している請求項５に記載の自然循環型沸騰水型原子炉。   The natural circulation boiling water reactor according to claim 5, wherein the blade member is curved. 前記羽根部材は肉厚が上流から下流に向かって減少している請求項５に記載の自然循環型沸騰水型原子炉。   The natural circulation boiling water reactor according to claim 5, wherein the blade member has a thickness that decreases from upstream to downstream. 前記羽根部材は上流側の端部が流線型をしている請求項４ないし請求項７のいずれか１項に記載の自然循環型沸騰水型原子炉。   The natural circulation boiling water reactor according to any one of claims 4 to 7, wherein the upstream end of the blade member has a streamline shape. 前記旋回流発生装置は、前記給水スパージャよりも上方に配置されている請求項１ないし請求項８のいずれか１項に記載の自然循環型沸騰水型原子炉。   The natural circulation boiling water reactor according to any one of claims 1 to 8, wherein the swirling flow generating device is disposed above the water supply sparger.
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EP3035338A1 (en) * 2014-12-19 2016-06-22 GE-Hitachi Nuclear Energy Americas LLC Reactor pressure vessel assembly including a flow barrier structure

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