JP6363381B2

JP6363381B2 - Flooring unit

Info

Publication number: JP6363381B2
Application number: JP2014081885A
Authority: JP
Inventors: 政隆日高; 一雄中島; 藤井　正; 正藤井; 酒井　健; 健酒井
Original assignee: Hitachi GE Nuclear Energy Ltd
Current assignee: Hitachi GE Nuclear Energy Ltd
Priority date: 2014-04-11
Filing date: 2014-04-11
Publication date: 2018-07-25
Anticipated expiration: 2034-04-11
Also published as: JP2015203590A; WO2015156178A1

Description

本発明は、原子炉格納容器の床面に配置される床材ユニットに関する。 The present invention relates to a flooring unit disposed on a floor surface of a reactor containment vessel.

一般的に、原子炉は、核燃料を封止した燃料棒を束ねた燃料集合体を保有する炉心を原子炉圧力容器及び原子炉格納容器の二重の防壁で取り囲み、核分裂生成物の外部への放散を防止している。加えて、原子炉には事故や非常時などの過渡事象に備えて非常用炉心冷却系等の炉心冷却設備からなる工学的安全設備が設けられており、例えば、地震、風水害等で外部電源を喪失しても、非常用発電機により非常用炉心冷却系が冷却機能を発揮し、炉心が過熱し溶融することを抑制する。しかし、万全を期するためには、非常用炉心冷却系が作動せず、溶融した炉心（炉心溶融物）が原子炉圧力容器の底部を侵食して貫通し落下した場合でも、核分裂生成物の放散を抑制する手段を講じる必要がある。 In general, a nuclear reactor surrounds a core containing a fuel assembly in which fuel rods sealed with nuclear fuel are bundled with a double barrier of a reactor pressure vessel and a containment vessel, and the fission product is released to the outside. Emission is prevented. In addition, nuclear reactors are equipped with engineering safety equipment consisting of core cooling equipment such as an emergency core cooling system in preparation for transient events such as accidents and emergencies. Even if lost, the emergency core cooling system exerts the cooling function by the emergency generator, and the core is prevented from overheating and melting. However, for the sake of completeness, even if the emergency core cooling system does not operate and the melted core (core melt) erodes and penetrates the bottom of the reactor pressure vessel, It is necessary to take measures to control the emission.

それに対し、例えば、原子炉圧力容器の下方に受け皿を上下方向に複数配置し、上部の受け皿の容量を超えた炉心溶融物を下部の受け皿で受け止めて複数段に分けて冷却する冷却構造が提唱されている（特許文献１等を参照）。 On the other hand, for example, a cooling structure is proposed in which a plurality of trays are arranged vertically below the reactor pressure vessel, and the core melt exceeding the capacity of the upper tray is received by the lower tray and cooled in multiple stages. (See Patent Document 1 and the like).

特開２０１３−２２１７７１号公報JP 2013-221771 A

引用文献１の冷却構造は、受け皿を上下方向に複数配置することにより特に上下方向に設置スペースを要する。設置スペースをとることから、既存の原子炉への適用が困難な場合も生じ得る。 The cooling structure of the cited document 1 requires an installation space particularly in the vertical direction by arranging a plurality of trays in the vertical direction. Due to the installation space, it may be difficult to apply to existing reactors.

本発明は、上記に鑑みてなされたもので、炉心溶融物の冷却性の向上により原子炉格納容器の床部への炉心溶融物の侵食を抑制することができるコンパクトな床材ユニットを提供することを目的とする。 The present invention has been made in view of the above, and provides a compact flooring unit capable of suppressing the erosion of the core melt to the floor portion of the reactor containment vessel by improving the cooling property of the core melt. For the purpose.

上記目的を達成するため、本発明の床材ユニットの一例は、床面に向かって落下する炉心溶融物を受ける第１伝熱板と、天井面及び底面をそれぞれ第２伝熱板及び第３伝熱板とし、第１伝熱板の下側に第２伝熱板が第１の空間を挟んで対向する少なくとも１つの炉心溶融物保持室と、第１伝熱板に設けた導入孔と炉心溶融物保持室とを接続する炉心溶融物導入流路と、前記第３伝熱板と前記原子炉格納容器の前記床面との間に第２の空間を確保するスペーサと、前記第１の空間と前記第２の空間とを連通する蒸気抜き管とを備える。 In order to achieve the above object, an example of a flooring unit of the present invention includes a first heat transfer plate that receives a core melt falling toward the floor surface, and a second heat transfer plate and a third heat transfer plate that are provided on the ceiling surface and the bottom surface, respectively. A heat transfer plate, and at least one core melt holding chamber facing the second heat transfer plate across the first space below the first heat transfer plate; an introduction hole provided in the first heat transfer plate; A core melt introduction flow path for connecting a core melt holding chamber, a spacer for securing a second space between the third heat transfer plate and the floor surface of the reactor containment vessel, and the first And a steam vent pipe communicating the second space with the second space .

本発明によれば、炉心溶融物の冷却性の向上により原子炉格納容器の床部への炉心溶融物の侵食を抑制することができるコンパクトな床材ユニットを提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the compact flooring unit which can suppress the erosion of the core melt to the floor part of a reactor containment vessel by the improvement of the cooling property of a core melt can be provided.

本発明の第１実施形態に係る床材ユニットを適用する原子炉格納容器の一構成例の概略構成を表す縦断面図である。It is a longitudinal section showing the schematic structure of the example of 1 composition of the reactor containment vessel to which the flooring unit concerning a 1st embodiment of the present invention is applied. 図１のＩＩ−ＩＩ矢視断面図である。It is II-II arrow sectional drawing of FIG. 本発明の第１実施形態に係る床材ユニットのセグメントを示す上面図である。It is a top view which shows the segment of the flooring unit which concerns on 1st Embodiment of this invention. 図３のＩＶ−ＩＶ矢視縦断面図である。FIG. 4 is a vertical cross-sectional view taken along arrow IV-IV in FIG. 3. 本発明の第１実施形態に係る床材ユニットに対する炉心溶融物の動作を説明する図である。It is a figure explaining operation | movement of the core melt with respect to the flooring unit which concerns on 1st Embodiment of this invention. 本発明の第１実施形態に係る床材ユニットに対する炉心溶融物の動作を説明する図である。It is a figure explaining operation | movement of the core melt with respect to the flooring unit which concerns on 1st Embodiment of this invention. 本発明の第１実施形態に係る床材ユニットに対する炉心溶融物の動作を説明する図である。It is a figure explaining operation | movement of the core melt with respect to the flooring unit which concerns on 1st Embodiment of this invention. 本発明の第１実施形態に係る床材ユニットに対する炉心溶融物の動作を説明する図である。It is a figure explaining operation | movement of the core melt with respect to the flooring unit which concerns on 1st Embodiment of this invention. 本発明の第２実施形態に係る床材ユニットのセグメントを示す上面図である。It is a top view which shows the segment of the flooring unit which concerns on 2nd Embodiment of this invention. 図６のＶＩＩ−ＶＩＩ矢視縦断面図である。It is a VII-VII arrow longitudinal cross-sectional view of FIG. 本発明の第３実施形態に係る床材ユニットのセグメントを示す上面図である。It is a top view which shows the segment of the flooring unit which concerns on 3rd Embodiment of this invention. 図８のＩＸ−ＩＸ矢視縦断面図である。It is the IX-IX arrow longitudinal cross-sectional view of FIG. 本発明の第４実施形態に係る床材ユニットのセグメントを示す上面図である。It is a top view which shows the segment of the flooring unit which concerns on 4th Embodiment of this invention. 図１０のＸＩ−ＸＩ矢視縦断面図である。It is a XI-XI arrow longitudinal cross-sectional view of FIG. 本発明の第５実施形態に係る床材ユニットのセグメントを示す上面図である。It is a top view which shows the segment of the flooring unit which concerns on 5th Embodiment of this invention. 図１２のＸＩＩＩ−ＸＩＩＩ矢視縦断面図である。It is a XIII-XIII arrow longitudinal cross-sectional view of FIG. 本発明の第６実施形態に係る床材ユニットのセグメントを示す上面図である。It is a top view which shows the segment of the flooring unit which concerns on 6th Embodiment of this invention. 図１４のＸＶ−ＸＶ矢視縦断面図である。It is a XV-XV arrow longitudinal cross-sectional view of FIG. 図１４のＸＶＩ−ＸＶＩ矢視縦断面図である。It is a XVI-XVI arrow longitudinal cross-sectional view of FIG.

＜第１実施形態＞
（構成）
１．原子炉格納容器
図１は本実施形態に係る床材ユニットを適用する原子炉格納容器の一構成例の概略構成を表す縦断面図、図２は図１のＩＩ−ＩＩ矢視断面図である。 <First Embodiment>
(Constitution)
1. 1 is a longitudinal sectional view showing a schematic configuration of one structural example of a reactor containment vessel to which a flooring unit according to this embodiment is applied, and FIG. 2 is a sectional view taken along the line II-II in FIG. .

図１に示すように、原子炉格納容器（格納容器）５０は原子炉圧力容器（圧力容器）１を格納している。圧力容器１は核燃料で構成される炉心（不図示）を収納している。格納容器５０の原子炉格納容器床（格納容器床）２には床面から上方に向かって延在する原子炉格納容器側壁（格納容器側壁）３が設けられている。格納容器側壁３は内壁面から圧力容器１に向かって突出する突出部３２を備えている。突出部３２には、圧力容器１に接続する圧力容器支持構造物２１が取り付けられている。すなわち、圧力容器１は圧力容器支持構造物２１を介して格納容器側壁３により支持されている。圧力容器１の下方には、格納容器床２及び格納容器側壁３等で囲まれた格納容器下部空間１０が形成されている。格納容器下部空間１０内には、炉心の出力を制御する制御棒を操作するための制御棒駆動機構、計装管等（不図示）を収容する圧力容器下部構造物１２が配置されている。格納容器５０は、格納容器５０の壁外から格納容器側壁３を貫通して格納容器下部空間１０内まで引き伸ばされた格納容器下部空間注水配管（注水配管）５を備えている。例えば、非常用炉心冷却系が作動しない場合には、注水配管５の注水口１６から格納容器下部空間１０内に冷却水Ｗ１が注水される。図中のＬ１は冷却水Ｗ１の注水により格納容器下部空間１０内に形成される水プールの水面を示している。冷却水Ｗ１の水源としては、例えば、復水貯蔵タンクや消火用のろ過水タンク（不図示）、海水等の外部水源などを利用することができる。格納容器下部空間１０への注水手段の他の例として、図示しない格納容器５０の空間（例えば、圧力容器１の側方）に貯えられた水を重力落下させ、その一部を圧力容器１と格納容器側壁３との間隙を通して格納容器下部区画１０へ流入させる機構もある。 As shown in FIG. 1, a reactor containment vessel (containment vessel) 50 stores a reactor pressure vessel (pressure vessel) 1. The pressure vessel 1 stores a core (not shown) made of nuclear fuel. The reactor containment vessel floor (containment vessel floor) 2 of the containment vessel 50 is provided with a reactor containment vessel side wall (containment vessel side wall) 3 extending upward from the floor surface. The storage container side wall 3 includes a protrusion 32 that protrudes from the inner wall surface toward the pressure container 1. A pressure vessel support structure 21 connected to the pressure vessel 1 is attached to the protruding portion 32. That is, the pressure vessel 1 is supported by the containment vessel side wall 3 via the pressure vessel support structure 21. A storage container lower space 10 surrounded by a storage container floor 2 and a storage container side wall 3 is formed below the pressure container 1. In the containment vessel lower space 10, a pressure vessel lower structure 12 that houses a control rod drive mechanism for operating a control rod for controlling the output of the core, an instrument tube, and the like (not shown) is disposed. The storage container 50 includes a storage container lower space water injection pipe (water injection pipe) 5 that extends from the outside of the storage container 50 through the storage container side wall 3 and extends into the storage container lower space 10. For example, when the emergency core cooling system does not operate, the cooling water W 1 is injected into the storage container lower space 10 from the water injection port 16 of the water injection pipe 5. L1 in the figure indicates the water surface of the water pool formed in the storage container lower space 10 by pouring the cooling water W1. As a water source of the cooling water W1, for example, a condensate storage tank, a fire-extinguishing filtered water tank (not shown), an external water source such as seawater, and the like can be used. As another example of means for injecting water into the storage container lower space 10, water stored in a space of the storage container 50 (not shown) (for example, the side of the pressure container 1) is dropped by gravity, and a part of the water is stored in the pressure container 1. There is also a mechanism for flowing into the storage container lower section 10 through a gap with the storage container side wall 3.

格納容器床２の床面には炉心溶融物保持構造材である床材ユニット６が配置されている。床材ユニット６は、圧力容器１の破損部８から落下した炉心溶融物４を保持して冷却する機能を有している。図２に示すように、床材ユニット６は複数のセグメント６ａ，６ｂ・・・の集合体であって、複数のセグメント６ａ，６ｂ・・・を格納容器５０の格納容器下部空間扉１１から搬入し格納容器床２上に配置して形成されている。本実施形態では、複数のセグメント６ａ，６ｂ・・・を互いに隣接するもの同士隙間をあけて格納容器床２を覆うように平面方向に並べてある。なお、本実施形態では、隣り合うセグメント同士は連結していない。複数のセグメント６ａ，６ｂ・・・は平面視で四角形状であるが（セグメント６ａを参照）、最外周に配置するものについては格納容器側壁３の内壁面の形状に沿うようにカットしてある（セグメント６ｂを参照）。以下、床材ユニット６のセグメントの構成についてセグメント６ａを例に挙げて説明する。 On the floor surface of the containment vessel floor 2, a floor material unit 6 which is a core melt holding structure material is disposed. The flooring unit 6 has a function of holding and cooling the core melt 4 dropped from the damaged portion 8 of the pressure vessel 1. As shown in FIG. 2, the flooring unit 6 is an aggregate of a plurality of segments 6 a, 6 b..., And the plurality of segments 6 a, 6 b, etc. are carried from the storage container lower space door 11 of the storage container 50. And arranged on the storage container floor 2. In this embodiment, a plurality of segments 6a, 6b,... Are arranged in the plane direction so as to cover the storage container floor 2 with a gap between them. In the present embodiment, adjacent segments are not connected to each other. The plurality of segments 6a, 6b,... Have a quadrangular shape in plan view (see segment 6a), but those arranged on the outermost periphery are cut so as to follow the shape of the inner wall surface of the storage container side wall 3. (See segment 6b). Hereinafter, the configuration of the segment of the flooring unit 6 will be described by taking the segment 6a as an example.

２．床材ユニット
図３は本実施形態に係る床材ユニットのセグメントを示す上面図、図４は図３のＩＶ−ＩＶ矢視縦断面図である。図３及び図４に示すように、セグメント６ａは、第１伝熱板７、炉心溶融物保持室１８及び炉心溶融物導入流路１５を備えている。以降、炉心溶融物保持室１８、炉心溶融物導入流路１５をそれぞれ保持室１８、導入流路１５と呼ぶ。 2. Floor Material Unit FIG. 3 is a top view showing segments of the floor material unit according to this embodiment, and FIG. 4 is a vertical cross-sectional view taken along arrows IV-IV in FIG. As shown in FIGS. 3 and 4, the segment 6 a includes a first heat transfer plate 7, a core melt holding chamber 18, and a core melt introduction flow path 15. Hereinafter, the core melt holding chamber 18 and the core melt introduction flow path 15 are referred to as a holding chamber 18 and an introduction flow path 15, respectively.

第１伝熱板７は平面視で四角形状（この例では正方形状）に形成された板部材である。第１伝熱板７は圧力容器１に格納容器下部空間１０を挟んで対向するように配置され、圧力容器１から格納容器床２に向かって落下する炉心溶融物４を受けて保持する。第１伝熱板７は導入孔３３と、複数（本実施形態では８つ）の蒸気抜き孔２０とを備えている。本実施形態では導入孔３３は平面視で第１伝熱板７の中心付近に設けられており、蒸気抜き孔２０は導入孔３３を囲むように設けられている。蒸気抜き孔２０は、格納容器下部空間１０と第１伝熱板７の下側に形成された第１の冷却水対流空間（第１の空間）１７とを連通している。第１伝熱板７は、上面７Ａが格納容器下部空間１０に面し、下面７Ｂが第１の空間１７に面しており、格納容器下部空間１０と第１の空間１７との境界を画定している。また、第１の空間１７の外周部は開放されていて、隣接する他のセグメントが備える第１の空間とセグメント６ａ間の隙間を介してつながっている。 The first heat transfer plate 7 is a plate member formed in a square shape (in this example, a square shape) in plan view. The first heat transfer plate 7 is disposed so as to face the pressure vessel 1 with the containment vessel lower space 10 interposed therebetween, and receives and holds the core melt 4 falling from the pressure vessel 1 toward the containment vessel floor 2. The first heat transfer plate 7 includes an introduction hole 33 and a plurality (eight in this embodiment) of steam release holes 20. In the present embodiment, the introduction hole 33 is provided near the center of the first heat transfer plate 7 in plan view, and the steam vent hole 20 is provided so as to surround the introduction hole 33. The steam vent 20 communicates with the storage container lower space 10 and a first cooling water convection space (first space) 17 formed below the first heat transfer plate 7. The first heat transfer plate 7 has an upper surface 7 A facing the storage container lower space 10 and a lower surface 7 B facing the first space 17, and demarcating the boundary between the storage container lower space 10 and the first space 17. doing. Moreover, the outer peripheral part of the 1st space 17 is open | released, and it is connected through the clearance gap between the 1st space with which another adjacent segment is provided, and the segment 6a.

保持室１８は第１伝熱板７の下側に位置しており、天井面及び底面をそれぞれ第２伝熱板１３及び第３伝熱板１４としている。第２伝熱板１３と第３伝熱板１４の互いの外縁部は閉止板１９で接続されていて、閉止板１９が保持室１８の全周を覆う側面を構成している。保持室１８は、上記導入流路１５との接続部を除き、閉空間構造に形成されている。第２伝熱板１３は平面視で外形線が正方形状に形成された板部材であり、第１伝熱板７の下側に第１の空間１７を挟んで対向している。つまり、第２伝熱板１３は、上面１３Ａが第１の空間１７に面し、下面１３Ｂが保持室１８の内部空間に面しており、第１の空間１７と保持室１８の内部空間との境界を画定している。第２伝熱板１３には孔３４及びガス抜き孔２４が設けられている。孔３４は第１伝熱板７の導入孔３３に対応する位置に設けられている。ガス抜き孔２４は保持室１８内と第１の空間１７とを連通するものであり、この例では保持室１８の四隅に対応する位置に設けられている。第３伝熱板１４は平面視で正方形状に形成された板部材であり、第２伝熱板１３の下側に保持室１８の内部空間を挟んで対向している。第３伝熱板１４は導入孔３３から流下する溶融デブリ（炉心溶融物４の液相部分）を受けて保持する。第３伝熱板１４の下面１４Ｂにはスペーサ２６が取り付けられており、第３伝熱板１４と格納容器床２との間には第２の冷却水対流空間（第２の空間）２３が確保されている。第３伝熱板１４は、上面１４Ａが保持室１８の内部空間に面し、下面１４Ｂが第２の空間２３に面しており、保持室１８の内部空間と第２の空間２３との境界を画定している。この例ではスペーサ２６は第３伝熱板１４の四隅に設けられている。第２の空間２３も、セグメント６ａ間の隙間を介して隣接する他のセグメントが備える第２の空間とつながっている。 The holding chamber 18 is located below the first heat transfer plate 7 and has a ceiling surface and a bottom surface as the second heat transfer plate 13 and the third heat transfer plate 14, respectively. The outer edge portions of the second heat transfer plate 13 and the third heat transfer plate 14 are connected by a closing plate 19, and the closing plate 19 constitutes a side surface covering the entire circumference of the holding chamber 18. The holding chamber 18 is formed in a closed space structure except for the connection portion with the introduction flow path 15. The second heat transfer plate 13 is a plate member whose outer shape is formed in a square shape in plan view, and is opposed to the lower side of the first heat transfer plate 7 with the first space 17 interposed therebetween. That is, the second heat transfer plate 13 has an upper surface 13A facing the first space 17 and a lower surface 13B facing the internal space of the holding chamber 18, and the first space 17 and the internal space of the holding chamber 18 The boundary is defined. The second heat transfer plate 13 is provided with a hole 34 and a gas vent hole 24. The hole 34 is provided at a position corresponding to the introduction hole 33 of the first heat transfer plate 7. The gas vent hole 24 communicates the inside of the holding chamber 18 and the first space 17, and is provided at positions corresponding to the four corners of the holding chamber 18 in this example. The third heat transfer plate 14 is a plate member formed in a square shape in plan view, and is opposed to the lower side of the second heat transfer plate 13 with the internal space of the holding chamber 18 interposed therebetween. The third heat transfer plate 14 receives and holds molten debris (liquid phase portion of the core melt 4) flowing down from the introduction hole 33. A spacer 26 is attached to the lower surface 14 B of the third heat transfer plate 14, and a second cooling water convection space (second space) 23 is provided between the third heat transfer plate 14 and the containment vessel floor 2. It is secured. The third heat transfer plate 14 has an upper surface 14 A facing the internal space of the holding chamber 18 and a lower surface 14 B facing the second space 23, and a boundary between the internal space of the holding chamber 18 and the second space 23. Is defined. In this example, the spacers 26 are provided at the four corners of the third heat transfer plate 14. The second space 23 is also connected to a second space provided in another adjacent segment through a gap between the segments 6a.

導入流路１５は第１の空間１７中を上下に延びて第１伝熱板７の導入孔３３と第２伝熱板１３の孔３４とを接続し、格納容器下部空間１０と保持室１８とを接続している。導入流路１５の内部空間は第１の空間１７と隔てられている。この導入流路１５の断面形状は特に限定されないが、本実施形態では平面視で円形状に形成されている。なお、導入流路１５は保持室１８の第２伝熱板１３に対して第１伝熱板７を支持する役割を兼ねている。また、第２伝熱板１３の上面１３Ａの外縁部には複数の第１伝熱板支持柱２２が立てられており、これら第１伝熱板支持柱２２によって第１伝熱板７を支持することにより第１伝熱板７の支持強度を強化してある。 The introduction flow path 15 extends vertically in the first space 17 to connect the introduction hole 33 of the first heat transfer plate 7 and the hole 34 of the second heat transfer plate 13, and the storage container lower space 10 and the holding chamber 18. And connected. The internal space of the introduction flow path 15 is separated from the first space 17. Although the cross-sectional shape of the introduction flow path 15 is not particularly limited, in the present embodiment, it is formed in a circular shape in plan view. The introduction flow path 15 also serves to support the first heat transfer plate 7 with respect to the second heat transfer plate 13 of the holding chamber 18. A plurality of first heat transfer plate support columns 22 are erected on the outer edge portion of the upper surface 13A of the second heat transfer plate 13, and the first heat transfer plate 7 is supported by the first heat transfer plate support columns 22. By doing so, the support strength of the first heat transfer plate 7 is strengthened.

（動作）
図５Ａ乃至図５Ｄは本実施形態に係る床材ユニットに対する炉心溶融物の動作を説明する図である。 (Operation)
5A to 5D are diagrams for explaining the operation of the core melt with respect to the flooring unit according to the present embodiment.

万一、圧力容器１への注水機能が停止した場合、例えば圧力容器１内の圧力変動に伴って、圧力容器１の破損部８から炉心溶融物４が落下する前に注水配管５から格納容器下部空間１０内に冷却水Ｗ１が注水される。格納容器下部空間１０内に注水された冷却水Ｗ１は、第２の空間２３、保持室１８、第１の空間１７を順次満たしていき、遂には床材ユニット６を冠水させ、格納容器下部空間１０に水プールを形成する（図１を参照）。圧力容器１の破損部８から格納容器床２に向かって落下する炉心溶融物４は水プール内を下方に落下し、セグメント６ａの第１伝熱板７上に受けられる。このとき、第１伝熱板７上の炉心溶融物４は一部が冷却水Ｗ１で冷却されるため固相部分と液相部分とが混在している。その結果、図５Ａに示すように、炉心溶融物４の液相部分である溶融デブリが第１伝熱板７の導入孔３３から導入流路１５内に流入し、下方に向かって導入流路１５を流れる。導入流路１５を下方に流れる溶融デブリは第３伝熱板１４上に落下し、図５Ｂに示すように、第３伝熱板１４に沿って広がり保持室１８内を満たしていく。保持室１８内の気体は溶融デブリにより閉止板１９側に押し込まれ、第２伝熱板１３に形成されたガス抜き孔２４を介して保持室１８内から第１の空間１７に抜けていく。保持室１８及び導入流路１５が溶融デブリで満たされると、第１伝熱板７から導入流路１５内への溶融デブリの流入が止まる。 In the unlikely event that the water injection function to the pressure vessel 1 is stopped, for example, due to the pressure fluctuation in the pressure vessel 1, the containment vessel 5 is inserted from the water injection pipe 5 before the core melt 4 drops from the damaged portion 8 of the pressure vessel 1. Cooling water W 1 is poured into the lower space 10. The cooling water W1 poured into the storage container lower space 10 sequentially fills the second space 23, the holding chamber 18, and the first space 17, and finally submerses the flooring unit 6, and the storage container lower space. A water pool is formed at 10 (see FIG. 1). The core melt 4 falling from the damaged portion 8 of the pressure vessel 1 toward the containment vessel floor 2 falls downward in the water pool and is received on the first heat transfer plate 7 of the segment 6a. At this time, since the core melt 4 on the first heat transfer plate 7 is partially cooled by the cooling water W1, the solid phase portion and the liquid phase portion are mixed. As a result, as shown in FIG. 5A, molten debris that is a liquid phase part of the core melt 4 flows into the introduction flow path 15 from the introduction hole 33 of the first heat transfer plate 7 and flows downward toward the introduction flow path. 15 flows. The molten debris flowing downward through the introduction flow path 15 falls on the third heat transfer plate 14, spreads along the third heat transfer plate 14, and fills the holding chamber 18, as shown in FIG. 5B. The gas in the holding chamber 18 is pushed into the closing plate 19 by molten debris, and escapes from the holding chamber 18 to the first space 17 through the gas vent holes 24 formed in the second heat transfer plate 13. When the holding chamber 18 and the introduction flow path 15 are filled with molten debris, the flow of molten debris from the first heat transfer plate 7 into the introduction flow path 15 stops.

導入流路１５の壁面及び第２伝熱板１３と接触する溶融デブリは第１の空間１７内の冷却水Ｗ１との熱交換により冷却され、閉止板１９と接触する溶融デブリは閉止板１９の外面側を流れる冷却水Ｗ１との熱交換により冷却され、第３伝熱板１４と接触する溶融デブリは第２の空間２３内の冷却水Ｗ１との熱交換により冷却される。その後、図５Ｃに示すように、導入流路１５及び保持室１８にある溶融デブリは、導入流路１５の壁面、第２伝熱板１３、閉止板１９及び第３伝熱板１４との各接触部にクラスト（溶融デブリが凝固したもの）を形成する。 The molten debris that contacts the wall surface of the introduction flow path 15 and the second heat transfer plate 13 is cooled by heat exchange with the cooling water W1 in the first space 17, and the molten debris that contacts the closing plate 19 The molten debris that is cooled by heat exchange with the cooling water W 1 flowing on the outer surface side and is in contact with the third heat transfer plate 14 is cooled by heat exchange with the cooling water W 1 in the second space 23. Thereafter, as shown in FIG. 5C, the molten debris in the introduction flow path 15 and the holding chamber 18 is separated from the wall surface of the introduction flow path 15, the second heat transfer plate 13, the closing plate 19, and the third heat transfer plate 14. Form crust (melted debris solidified) at the contact area.

第１の空間１７内では、図５Ｃに示すように、溶融デブリとの熱交換により冷却水Ｗ１が加熱されて沸騰し蒸気泡が生じる。この蒸気泡は、第１の空間１７内の冷却水Ｗ１を巻き込みながら浮力により上昇し、第１伝熱板７の下面７Ｂに衝突する。第１の空間１７内を第１伝熱板７に向かって上昇する蒸気泡と、第１伝熱板７上の炉心溶融物４との熱交換により第１伝熱板７の下面７Ｂ付近で生じた蒸気泡とは、図５Ｃに示すように、第１伝熱板７に形成された蒸気抜き孔２０を通ったり、図５Ｄに示すように、隣接するセグメント６ａ間の隙間を通ったりして第１の空間１７から第１伝熱板７の上方に抜けていく。第２空間２３内でも、保持室１８内の溶融デブリとの熱交換により冷却水Ｗ１が加熱されて沸騰し蒸気泡が生じる。この蒸気泡は、図５Ｄに示すように、隣接するセグメント６ａ間の隙間などを介して第１伝熱板７の上方に抜けていく。 In the first space 17, as shown in FIG. 5C, the cooling water W 1 is heated by heat exchange with the molten debris to boil and produce steam bubbles. The steam bubbles rise by buoyancy while entraining the cooling water W 1 in the first space 17, and collide with the lower surface 7 B of the first heat transfer plate 7. In the vicinity of the lower surface 7 B of the first heat transfer plate 7 by heat exchange between the steam bubbles rising toward the first heat transfer plate 7 in the first space 17 and the core melt 4 on the first heat transfer plate 7. The generated steam bubbles pass through the steam vent holes 20 formed in the first heat transfer plate 7 as shown in FIG. 5C, or pass through the gaps between the adjacent segments 6a as shown in FIG. 5D. Thus, the first heat transfer plate 7 passes through the first space 17. Even in the second space 23, the cooling water W 1 is heated by heat exchange with the molten debris in the holding chamber 18, and boils to generate steam bubbles. As shown in FIG. 5D, the vapor bubbles escape above the first heat transfer plate 7 through a gap between the adjacent segments 6a.

（効果）
（１）炉心溶融物の床部への侵食抑制
まず、下側に第１の空間１７がある第１伝熱板７で炉心溶融物４を受けることにより、格納容器下部空間１０内の冷却水Ｗ１により第１伝熱板７上の炉心溶融物４を上側から冷却することができる。加えて、格納容器床２との熱交換に代えて、第１伝熱板７上の炉心溶融物４を第１の空間１７内の冷却水Ｗ１との熱交換により下側からも次の作用により効果的に冷却することができる。すなわち、導入流路１５を介して一部の炉心溶融物４（溶融デブリ）を保持室１８に導くことにより、溶融デブリとの熱交換により第１の空間１７内に蒸気泡を発生させ、この蒸気泡と第１の空間１７内の冷却水Ｗ１との気液二相流を第１伝熱面の下面７Ｂに衝突させることができる。そのため、第１伝熱板７を継続的に冷却し、第１伝熱板７上の炉心溶融物４を下側からも効果的に冷却することができる。仮に保持室１８を設けず第１伝熱板７上の炉心溶融物４との熱交換により第１の空間１７内の冷却水Ｗ１の上部のみを加熱する場合、第１の空間１７内の冷却水Ｗ１の流動は自然対流に依存することになる。それに対し、本実施形態では保持室１８に溶融デブリを導くことにより、第１の空間１７内の冷却水Ｗ１を下からも過熱して強制的に対流させることができるので、冷却水Ｗ１の自然対流に依存する場合よりも大きな除熱量が得られる。 (effect)
(1) Inhibition of erosion of core melt to floor portion First, cooling water in the lower space 10 of the containment vessel is received by receiving the core melt 4 by the first heat transfer plate 7 having the first space 17 on the lower side. The core melt 4 on the first heat transfer plate 7 can be cooled from the upper side by W1. In addition, instead of heat exchange with the containment vessel floor 2, the core melt 4 on the first heat transfer plate 7 is exchanged with the cooling water W 1 in the first space 17 for the following action from below. Can be effectively cooled. That is, a part of the core melt 4 (molten debris) is guided to the holding chamber 18 through the introduction flow path 15 to generate steam bubbles in the first space 17 by heat exchange with the molten debris. The gas-liquid two-phase flow of the steam bubbles and the cooling water W1 in the first space 17 can collide with the lower surface 7B of the first heat transfer surface. Therefore, the first heat transfer plate 7 can be continuously cooled, and the core melt 4 on the first heat transfer plate 7 can be effectively cooled from the lower side. If only the upper part of the cooling water W 1 in the first space 17 is heated by heat exchange with the core melt 4 on the first heat transfer plate 7 without providing the holding chamber 18, the cooling in the first space 17 is performed. The flow of the water W1 depends on natural convection. On the other hand, in this embodiment, by introducing the molten debris into the holding chamber 18, the cooling water W1 in the first space 17 can be overheated and forcedly convected from below, so that the natural cooling water W1 A greater amount of heat removal can be obtained than when relying on convection.

また、導入流路１５及び保持室１８内に導かれた溶融デブリも第１の空間１７及び第２空間１８内の冷却水Ｗ１との熱交換により冷却し凝固させることができる。第２の空間２３内の冷却水Ｗ１は保持室１８内の溶融デブリとの熱交換により上からのみしか加熱されず流動は自然対流に依存するが、溶融デブリの冷却には十分である。保持室１８内の溶融デブリは第１伝熱板７上に保持される炉心溶融物４に比べて少量であり、保持室１８の底面である第３伝熱板１４は第１伝熱板７と同程度の十分な伝熱面積を有するためである。したがって、溶融デブリが第３伝熱板１４を貫通して格納容器５０の床部に落下することも抑制できる。 Also, the molten debris introduced into the introduction flow path 15 and the holding chamber 18 can be cooled and solidified by heat exchange with the cooling water W 1 in the first space 17 and the second space 18. The cooling water W1 in the second space 23 is heated only from above by heat exchange with the molten debris in the holding chamber 18, and the flow depends on natural convection, but is sufficient for cooling the molten debris. The molten debris in the holding chamber 18 is smaller than the core melt 4 held on the first heat transfer plate 7, and the third heat transfer plate 14, which is the bottom surface of the holding chamber 18, is the first heat transfer plate 7. This is because it has a sufficient heat transfer area of the same level. Therefore, it is possible to prevent the molten debris from penetrating through the third heat transfer plate 14 and falling to the floor of the storage container 50.

以上により、炉心溶融物４の冷却性を向上させ格納容器５０の床部への炉心溶融物４の侵食を抑制することができる。 As described above, the cooling property of the core melt 4 can be improved, and the erosion of the core melt 4 to the floor portion of the containment vessel 50 can be suppressed.

（２）床材ユニットの省スペース化
本実施形態の床材ユニット６は基本的に第１伝熱板７上で炉心溶融物４を冷却する構造であり、第１の空間１７内の冷却水Ｗ１を下から加熱するのに必要な量の溶融デブリが保持室１８に導かれれば、導入流路１５及び保持室１８が満たされて炉心溶融物４の大部分は第１伝熱板７上に保持される。このように保持室１８はあくまで第１の空間１７内の冷却水Ｗ１を下から加熱するための一部の炉心溶融物４を導き入れる程度の容積で足りるので床材ユニット６をコンパクトに構成することができる。 (2) Space saving of flooring unit The flooring unit 6 of the present embodiment is basically structured to cool the core melt 4 on the first heat transfer plate 7, and the cooling water in the first space 17. When the amount of molten debris necessary for heating W1 from below is introduced into the holding chamber 18, the introduction flow path 15 and the holding chamber 18 are filled, and most of the core melt 4 is the first heat transfer plate 7. Held on. Thus, since the holding chamber 18 only needs a volume enough to introduce a part of the core melt 4 for heating the cooling water W1 in the first space 17 from below, the flooring unit 6 is configured compactly. be able to.

（３）蒸気膜の形成抑制
第１の空間１７内では溶融デブリとの熱交換により冷却水Ｗ１の蒸気泡が連続的に発生し得る。そのため、第１伝熱板７の下面７Ｂ付近で複数の蒸気泡が合体して蒸気膜を形成してしまうと、この蒸気膜が第１伝熱板７の下面７Ｂを覆うことにより蒸気泡と冷却水Ｗ１との気液二相流を第１伝熱板７の下面７Ｂに衝突させることができない可能性がある。これに対し、本実施形態では、セグメント６ａは格納容器下部空間１０と第１の空間１７とを連通する第１蒸気抜き孔２０を備えている。これにより、第１の空間１７内で発生した蒸気泡を第１蒸気抜き孔２０を通して第１の空間１７から第１の伝熱板７の上方に円滑に抜くことができる。また、上記蒸気泡を隣接するセグメント６ａ間の隙間を通して第１の伝熱板７の上方に円滑に抜くこともできる。したがって、第１伝熱板７の下面７Ｂが蒸気膜で覆われることを抑制することができる。その結果、蒸気泡と冷却水Ｗ１との気液二相流をより確実に第１伝熱板７の下面７Ｂに衝突させることができる。 (3) Suppression of formation of vapor film In the first space 17, vapor bubbles of the cooling water W1 can be continuously generated by heat exchange with the molten debris. Therefore, when a plurality of vapor bubbles are combined in the vicinity of the lower surface 7B of the first heat transfer plate 7 to form a vapor film, the vapor film covers the lower surface 7B of the first heat transfer plate 7 to There is a possibility that the gas-liquid two-phase flow with the cooling water W 1 cannot collide with the lower surface 7 B of the first heat transfer plate 7. On the other hand, in the present embodiment, the segment 6 a includes a first vapor vent hole 20 that allows the storage container lower space 10 and the first space 17 to communicate with each other. Thereby, the vapor bubbles generated in the first space 17 can be smoothly extracted from the first space 17 to the upper side of the first heat transfer plate 7 through the first vapor vent hole 20. Moreover, the said vapor bubble can also be smoothly extracted above the 1st heat exchanger plate 7 through the clearance gap between the adjacent segments 6a. Therefore, it is possible to suppress the lower surface 7B of the first heat transfer plate 7 from being covered with the vapor film. As a result, the gas-liquid two-phase flow of the steam bubbles and the cooling water W1 can be made to collide with the lower surface 7B of the first heat transfer plate 7 more reliably.

（４）保持室内への溶融デブリの導入性向上
本実施形態では、第２伝熱板１３にガス抜き孔２４を形成し、第１の空間１７と保持室１８とを連通させている。そのため、保持室１８内の気体をガス抜き孔２４を介して保持室１８内から第１の空間１７に抜くことができ、保持室１８内の気体により溶融デブリの保持室１８内への広がりが損なわれることを抑制できる。 (4) Improvement of Introducibility of Molten Debris into Holding Chamber In the present embodiment, a gas vent hole 24 is formed in the second heat transfer plate 13 so that the first space 17 and the holding chamber 18 are communicated. Therefore, the gas in the holding chamber 18 can be extracted from the holding chamber 18 to the first space 17 through the gas vent hole 24, and the gas in the holding chamber 18 spreads the molten debris into the holding chamber 18. It is possible to suppress damage.

＜第２実施形態＞
図６は本実施形態に係る床材ユニットのセグメントを示す上面図、図７は図６のＶＩＩ−ＶＩＩ矢視縦断面図である。図６及び図７において、上記第１実施形態と同等の部分には同一の符号を付し、適宜説明を省略する。 Second Embodiment
FIG. 6 is a top view showing segments of the flooring unit according to the present embodiment, and FIG. 7 is a vertical sectional view taken along arrow VII-VII in FIG. 6 and 7, the same reference numerals are given to the same parts as those in the first embodiment, and the description will be omitted as appropriate.

図７に示すように、本実施形態に係るセグメント１６ａでは、導入流路１５は流路幅が下方に向かって拡大している。すなわち、導入流路１５は入口側（導入孔３３側）よりも出口側（孔３４側）の流路幅が広くなっている。導入流路１５は、例えばテーパ状に広がる形状でも良いが、本実施形態ではＲ状（ラッパ状）に広がっている。その他の構成は第１実施形態と同様である。 As shown in FIG. 7, in the segment 16a according to the present embodiment, the introduction channel 15 has a channel width expanding downward. In other words, the introduction channel 15 has a wider channel width on the outlet side (hole 34 side) than on the inlet side (introduction hole 33 side). The introduction flow path 15 may have, for example, a shape that expands in a taper shape, but in this embodiment, the introduction flow channel 15 extends in an R shape (trumpet shape). Other configurations are the same as those of the first embodiment.

本実施形態によれば、第１実施形態と同様の効果に加えて、次の効果が得られる。 According to this embodiment, in addition to the same effects as those of the first embodiment, the following effects can be obtained.

導入流路１５が直管形状の場合、導入流路１５から保持室１８に流入する際に溶融デブリの流れ方向が下方から水平方向へ急激に変化する。そのため、溶融デブリは導入流路１５を流下した速度で第３伝熱板１４に衝突し、第３伝熱板１４への熱負荷が増加してしまう可能性がある。これに対し、本実施形態では、導入流路１５の流路幅が下方に向かって拡大している。そのため、溶融デブリの流れ方向を水平方向に緩やかに変化させることができる。したがって、第３伝熱板１４へ衝突する溶融デブリの速度を減少し、第３伝熱板１４への熱負荷を緩和することができる。更に、導入流路１５の流路断面積が下方ほど広くなるため、溶融デブリの凝固等により、保持室１８内に溶融デブリが充填される前に導入流路１５、傾斜導入流路２７、及び保持室１８等が閉塞されることを抑制し、保持室１８内の溶融デブリの充填率を向上させることができる。したがって、第１の空間１７内で蒸気泡を十分に発生させ、第１伝熱板７の除熱量を十分に確保することができる。以上より、炉心溶融物４の冷却性をより向上させ格納容器５０の床部への炉心溶融物４の侵食をより抑制することができる。 When the introduction channel 15 has a straight pipe shape, the flow direction of the molten debris rapidly changes from the lower side to the horizontal direction when flowing into the holding chamber 18 from the introduction channel 15. Therefore, the molten debris may collide with the third heat transfer plate 14 at a speed that flows down the introduction flow path 15, and the heat load on the third heat transfer plate 14 may increase. On the other hand, in this embodiment, the flow path width of the introduction flow path 15 is expanded downward. Therefore, the flow direction of the molten debris can be gradually changed in the horizontal direction. Therefore, the speed of the molten debris colliding with the third heat transfer plate 14 can be reduced, and the heat load on the third heat transfer plate 14 can be reduced. Furthermore, since the flow passage cross-sectional area of the introduction flow passage 15 becomes wider downward, the introduction flow passage 15, the inclined introduction flow passage 27, and the like before the molten debris is filled into the holding chamber 18 due to solidification of the molten debris, etc. It is possible to suppress the holding chamber 18 and the like from being blocked, and to improve the filling rate of the molten debris in the holding chamber 18. Therefore, it is possible to sufficiently generate steam bubbles in the first space 17 and to ensure a sufficient heat removal amount of the first heat transfer plate 7. As described above, the cooling property of the core melt 4 can be further improved, and the erosion of the core melt 4 to the floor portion of the containment vessel 50 can be further suppressed.

＜第３実施形態＞
図８は本実施形態に係る床材ユニットのセグメントを示す上面図、図９は図８のＩＸ−ＩＸ矢視縦断面図である。図８及び図９において、上記第１実施形態と同等の部分には同一の符号を付し、適宜説明を省略する。 <Third Embodiment>
FIG. 8 is a top view showing segments of the flooring unit according to the present embodiment, and FIG. 9 is a longitudinal sectional view taken along arrow IX-IX in FIG. 8 and 9, the same reference numerals are given to the same parts as those in the first embodiment, and the description will be omitted as appropriate.

図８及び図９に示すように、本実施形態に係るセグメント２６ａは蒸気抜き管２８を備えている。蒸気抜き管２８は、保持室１８を貫通するように設けられ、第１の空間１７と第２の空間２３とを連通している。蒸気抜き管２８は、平面視で断面が円形状に形成されている。本実施形態では、蒸気抜き管２８は導入孔３３を囲むように４つ設けられている。その他の構成は第２実施形態と同様である。 As shown in FIGS. 8 and 9, the segment 26 a according to this embodiment includes a steam vent pipe 28. The vapor vent pipe 28 is provided so as to penetrate the holding chamber 18, and communicates the first space 17 and the second space 23. The vapor vent pipe 28 has a circular cross section in plan view. In the present embodiment, four steam vent pipes 28 are provided so as to surround the introduction hole 33. Other configurations are the same as those of the second embodiment.

上記構成により、本実施形態によれば、第２実施形態と同様の効果に加えて次の効果が得られる。 With the above configuration, according to the present embodiment, the following effect is obtained in addition to the same effect as the second embodiment.

第２の空間２３内の蒸気泡は隣接するセグメントとの間の隙間から第１伝熱板７の上方に抜けていく（図４Ｄ参照）が、第２の空間２３内を隙間に向かって移動する過程で他の蒸気泡と合体して蒸気膜を形成してしまうと、この蒸気膜が第３伝熱板１４の下面１４Ｂを覆うことにより第３伝熱板１４の熱伝達率が低下する可能性がある。また、床材ユニット６を複数のセグメントの集合体でなく一体構造とし、セグメント間に隙間が確保できない場合もある。この場合には、第２の空間２３内の蒸気泡を床材ユニット６と格納容器側壁３との隙間から第１伝熱板７の上方に抜くことになるが、格納容器側壁３側に向かって移動する過程で他の蒸気泡と合体して蒸気膜を形成し、第３伝熱板１４の下面１４Ｂを蒸気膜が覆う可能性も高まる。 The vapor bubbles in the second space 23 escape from the gap between the adjacent segments to the upper side of the first heat transfer plate 7 (see FIG. 4D), but move in the second space 23 toward the gap. If a vapor film is formed by combining with other vapor bubbles in the process, the vapor film covers the lower surface 14B of the third heat transfer plate 14, thereby reducing the heat transfer coefficient of the third heat transfer plate 14. there is a possibility. In some cases, the flooring unit 6 is not an assembly of a plurality of segments but an integrated structure, and a gap cannot be secured between the segments. In this case, the vapor bubbles in the second space 23 are drawn above the first heat transfer plate 7 from the gap between the flooring unit 6 and the storage container side wall 3, but toward the storage container side wall 3 side. In the process of moving, a vapor film is formed by combining with other vapor bubbles, and the possibility that the vapor film covers the lower surface 14B of the third heat transfer plate 14 is also increased.

これに対し、本実施形態では、第１の空間１７と第２の空間２３とを連通する蒸気抜き管２８が備えられている。そのため、第２の空間２３内で発生した蒸気泡を第２の空間２３から第１の空間１７に抜くことができ、第３伝熱板１４の下面１４Ｂが蒸気膜で覆われることを抑制して第３伝熱板１４の熱伝達率を確保することができる。更に、第２の空間２３から第１の空間１７に抜けた蒸気泡を第１の空間１７内の蒸気泡に加えることにより、第１伝熱板７に向けて上昇する蒸気泡の浮力を増加させ、第１伝熱板７の下面７Ｂに対する冷却水Ｗ１の衝突速度を増加させることができ、第１伝熱板７の除熱量を増加させることができる。以上より、炉心溶融物４の冷却性をより向上させ格納容器５０の床部への炉心溶融物４の侵食をより抑制することができる。 On the other hand, in the present embodiment, a steam vent pipe 28 that communicates the first space 17 and the second space 23 is provided. Therefore, the vapor bubbles generated in the second space 23 can be extracted from the second space 23 to the first space 17, and the lower surface 14B of the third heat transfer plate 14 is prevented from being covered with the vapor film. Thus, the heat transfer coefficient of the third heat transfer plate 14 can be ensured. Furthermore, the buoyancy of the steam bubbles rising toward the first heat transfer plate 7 is increased by adding the steam bubbles that have escaped from the second space 23 to the first space 17 to the steam bubbles in the first space 17. The collision speed of the cooling water W1 against the lower surface 7B of the first heat transfer plate 7 can be increased, and the heat removal amount of the first heat transfer plate 7 can be increased. As described above, the cooling property of the core melt 4 can be further improved, and the erosion of the core melt 4 to the floor portion of the containment vessel 50 can be further suppressed.

＜第４実施形態＞
図１０は本実施形態に係る床材ユニットのセグメントを示す上面図、図１１は図１０のＸＩ−ＸＩ矢視縦断面図である。図１０及び図１１において、上記第１実施形態と同等の部分には同一の符号を付し、適宜説明を省略する。 <Fourth embodiment>
FIG. 10 is a top view showing segments of the flooring unit according to the present embodiment, and FIG. 11 is a longitudinal sectional view taken along arrow XI-XI in FIG. 10 and 11, the same reference numerals are given to the same parts as those in the first embodiment, and the description will be omitted as appropriate.

図１０及び図１１に示すように、本実施形態に係るセグメント３６ａは、第１伝熱板７の縁部に形成された第１伝熱板流通流路（切り欠き）２９を備えている。切り欠き２９は、平面視で半円形状に形成されている。本実施形態では、切り欠き２９は第１伝熱板７の各辺に３つずつ設けられていて隣接するセグメントの切り欠き２９と対向するようにしてある。その他の構成は第２実施形態と同様である。 As shown in FIGS. 10 and 11, the segment 36 a according to the present embodiment includes a first heat transfer plate circulation channel (notch) 29 formed at the edge of the first heat transfer plate 7. The notch 29 is formed in a semicircular shape in plan view. In the present embodiment, three cutouts 29 are provided on each side of the first heat transfer plate 7 so as to face the cutouts 29 of adjacent segments. Other configurations are the same as those of the second embodiment.

上記構成により、本実施形態によれば、第２実施形態と同様の効果に加えて、次の効果が得られる。 With the above configuration, according to the present embodiment, in addition to the same effects as those of the second embodiment, the following effects can be obtained.

本実施形態では、第１伝熱板７の縁部に形成された切り欠き２９が備えられている。そのため、第１の空間１７内で発生した蒸気泡を空気抜き孔２０及び切り欠き２９から第１伝熱板７の上方に抜くことができる。したがって、第１伝熱板７の下面７Ｂが蒸気膜で覆われることを抑制し、第１伝熱板７の除熱量を十分に確保することができる。また、複数のセグメントを単に並べるのではなく、隣接するもの同士を溶接等により連結し、一体構造とした場合にもセグメント間に切り欠き２９による孔を確保することができるため、第１の空間１７内で発生した蒸気泡を第１伝熱板７の上方に抜くことができる。したがって、この場合にも第１伝熱板７の下面７Ａが蒸気膜で覆われることを抑制し、第１伝熱板７の除熱量を十分に確保することができる。以上より、炉心溶融物４の冷却性をより向上させ格納容器５０の床部への炉心溶融物４の侵食をより抑制することができる。 In this embodiment, the notch 29 formed in the edge part of the 1st heat exchanger plate 7 is provided. Therefore, the vapor bubbles generated in the first space 17 can be extracted above the first heat transfer plate 7 from the air vent hole 20 and the notch 29. Therefore, it can suppress that lower surface 7B of the 1st heat exchanger plate 7 is covered with a vapor | steam film | membrane, and can fully ensure the heat removal amount of the 1st heat exchanger plate 7. FIG. In addition, since the plurality of segments are not simply arranged, but adjacent ones are connected by welding or the like to form an integral structure, a hole by the notch 29 can be secured between the segments. The steam bubbles generated in 17 can be extracted above the first heat transfer plate 7. Therefore, also in this case, the lower surface 7A of the first heat transfer plate 7 can be suppressed from being covered with the vapor film, and the heat removal amount of the first heat transfer plate 7 can be sufficiently ensured. As described above, the cooling property of the core melt 4 can be further improved, and the erosion of the core melt 4 to the floor portion of the containment vessel 50 can be further suppressed.

＜第５実施形態＞
図１２は本実施形態に係る床材ユニットのセグメントを示す上面図、図１３は図１２のＸＩＩＩ−ＸＩＩＩ矢視縦断面図である。図１２及び図１３において、上記第１実施形態と同等の部分には同一の符号を付し、適宜説明を省略する。 <Fifth Embodiment>
FIG. 12 is a top view showing segments of the flooring unit according to the present embodiment, and FIG. 13 is a vertical sectional view taken along the line XIII-XIII in FIG. 12 and 13, the same reference numerals are given to the same parts as those in the first embodiment, and the description will be omitted as appropriate.

図８及び図９に示すように、本実施形態に係るセグメント４６ａは、第１伝熱板４７が導入孔３３に向かって下り傾斜に形成されている。すなわち、第１伝熱板４７が、外縁部に対して導入孔３３が下側（保持室１８側）に位置するように形成されている。その他の構成は第２実施形態と同様である。 As shown in FIGS. 8 and 9, in the segment 46 a according to this embodiment, the first heat transfer plate 47 is formed to be inclined downward toward the introduction hole 33. That is, the first heat transfer plate 47 is formed such that the introduction hole 33 is located on the lower side (the holding chamber 18 side) with respect to the outer edge portion. Other configurations are the same as those of the second embodiment.

本実施形態では、第１伝熱板４７が導入孔３３に向かって下り傾斜に形成されている。そのため、第１伝熱板４７上の炉心溶融物４の溶融デブリを重力を利用して導入流路１５に積極的に流入させることができ、冷却機能の信頼性を高めることができる。また、第１冷却水流路１７内の蒸気泡、及び第１伝熱板４７の下面４７Ｂ付近の蒸気泡の第１伝熱板４７の外縁側への流動を促進し、これらの蒸気泡を空気抜き孔２０及びセグメント４６ａ間の隙間から第１伝熱板４７の上方へ容易に抜くことができる。したがって、第１伝熱板４７の下面４７Ｂが蒸気膜で覆われることをより効果的に抑制することができる。複数のセグメントを溶接等により連結して一体構造とした場合にも、格納容器側壁３側に向かう蒸気泡の速度を増加させ、蒸気泡を第１伝熱板４７の上方へ迅速に抜くことができる。したがって、この場合にも第１伝熱板４７の下面４７Ｂが蒸気膜で覆われることをより効果的に抑制することができる。以上より、炉心溶融物４の冷却性をより向上させ格納容器５０の床部への炉心溶融物４の侵食をより抑制することができる。 In the present embodiment, the first heat transfer plate 47 is formed to be inclined downward toward the introduction hole 33. Therefore, the molten debris of the core melt 4 on the first heat transfer plate 47 can be actively flowed into the introduction flow path 15 using gravity, and the reliability of the cooling function can be improved. Further, the flow of the steam bubbles in the first cooling water channel 17 and the steam bubbles near the lower surface 47B of the first heat transfer plate 47 to the outer edge side of the first heat transfer plate 47 is promoted, and these steam bubbles are vented. The first heat transfer plate 47 can be easily pulled out from the gap between the hole 20 and the segment 46a. Therefore, it can suppress more effectively that lower surface 47B of the 1st heat exchanger plate 47 is covered with a vapor film. Even when a plurality of segments are connected by welding or the like to form an integrated structure, it is possible to increase the speed of the steam bubbles toward the storage container side wall 3 and quickly remove the steam bubbles above the first heat transfer plate 47. it can. Therefore, also in this case, the lower surface 47B of the first heat transfer plate 47 can be more effectively suppressed from being covered with the vapor film. As described above, the cooling property of the core melt 4 can be further improved, and the erosion of the core melt 4 to the floor portion of the containment vessel 50 can be further suppressed.

＜第６実施形態＞
図１４は本実施形態に係る床材ユニットのセグメントを示す上面図、図１５は図１４のＸＶ−ＸＶ矢視縦断面図、図１６は図１４のＸＶＩ−ＸＶＩ矢視縦断面図である。図１４乃至図１６において、上記第１実施形態と同等の部分には同一の符号を付し、適宜説明を省略する。 <Sixth Embodiment>
14 is a top view showing segments of the flooring unit according to the present embodiment, FIG. 15 is a vertical cross-sectional view taken along arrow XV-XV in FIG. 14, and FIG. 16 is a vertical cross-sectional view taken along arrow XVI-XVI in FIG. 14 to 16, the same reference numerals are given to the same parts as those in the first embodiment, and the description will be omitted as appropriate.

本実施形態に係るセグメント５６ａにおいては、図１４に示すように、保持室１８が平面視で対称形を成す十字型に形成されており、保持室１８の周囲で第１の空間１７と第２の空間２３とが広く接続している。具体的には、第２伝熱板１３及び第３伝熱板１４がそれぞれ断面Ｕ字形状に形成されていて、図１６に示すように、第２伝熱板１３と第３伝熱板１４とで断面が円形の管路を形成している。すなわち、保持室１８は第２伝熱板１３及び第３伝熱板１４を周壁とする、断面が円形の管路形状に形成されている。 In the segment 56 a according to the present embodiment, as shown in FIG. 14, the holding chamber 18 is formed in a cruciform shape that is symmetrical in plan view, and the first space 17 and the second space around the holding chamber 18 are formed. The space 23 is widely connected. Specifically, the second heat transfer plate 13 and the third heat transfer plate 14 are each formed in a U-shaped cross section, and as shown in FIG. 16, the second heat transfer plate 13 and the third heat transfer plate 14 are formed. And a pipe having a circular cross section is formed. That is, the holding chamber 18 is formed in a pipe shape having a circular section with the second heat transfer plate 13 and the third heat transfer plate 14 as peripheral walls.

図１５に示すように、第３伝熱板１４の下側には第２の空間２３を挟んで第３伝熱板１４に対向する第４伝熱板３５が備えられている。第４伝熱板３５は平面視で正方形状に形成された板部材である。第４伝熱板３５の下面３５Ｂにはスペーサ２６が取り付けられており、第４伝熱板３５と格納容器５０の床面２との間には第３の冷却水対流空間（第３の空間）３６が確保されている。すなわち、本実施形態では第３伝熱板１４は格納容器５０の床部２に支持されておらず、保持室１８は導入流路１５を介して第１の空間１７中に吊り下げられた状態で配置されている。なお、本実施形態では、第４伝熱板３５の上面３５Ａの外縁部に第１伝熱板支持柱２２が立てられ、第１伝熱板支持柱２２を介して第４伝熱板３５で第１伝熱板７を支持している。その他の構成は第１実施形態と同様である。 As shown in FIG. 15, a fourth heat transfer plate 35 is provided below the third heat transfer plate 14 so as to face the third heat transfer plate 14 with the second space 23 interposed therebetween. The fourth heat transfer plate 35 is a plate member formed in a square shape in plan view. A spacer 26 is attached to the lower surface 35B of the fourth heat transfer plate 35, and a third cooling water convection space (third space) is provided between the fourth heat transfer plate 35 and the floor surface 2 of the containment vessel 50. ) 36 is secured. That is, in the present embodiment, the third heat transfer plate 14 is not supported by the floor portion 2 of the containment vessel 50, and the holding chamber 18 is suspended in the first space 17 through the introduction flow path 15. Is arranged in. In the present embodiment, the first heat transfer plate support column 22 is erected on the outer edge portion of the upper surface 35A of the fourth heat transfer plate 35, and the fourth heat transfer plate 35 is interposed via the first heat transfer plate support column 22. The first heat transfer plate 7 is supported. Other configurations are the same as those of the first embodiment.

本実施形態では、第３伝熱板１４の下側に第２の空間２３を挟んで対向する第４伝熱板３５を備えている。そのため、万一、第３伝熱板１４が保持室１８内の溶融デブリにより浸食され破損した場合でも、破損部から落下する溶融デブリを第４伝熱板３５で保持することができる。第４伝熱板３５で保持された溶融デブリは、第３の空間３６内の冷却水Ｗ１との熱交換により冷却し凝固させることができる。したがって、第３伝熱板１４及び第４伝熱板３５の二重の防護境界により格納容器５０の床面２への溶融デブリの落下を防止することができる。 In this embodiment, the 4th heat exchanger plate 35 which opposes on both sides of the 2nd space 23 under the 3rd heat exchanger plate 14 is provided. Therefore, even if the third heat transfer plate 14 is eroded and damaged by the molten debris in the holding chamber 18, the molten debris falling from the damaged portion can be held by the fourth heat transfer plate 35. The molten debris held by the fourth heat transfer plate 35 can be cooled and solidified by heat exchange with the cooling water W 1 in the third space 36. Therefore, it is possible to prevent the molten debris from falling onto the floor surface 2 of the containment vessel 50 by the double protective boundary between the third heat transfer plate 14 and the fourth heat transfer plate 35.

また、本実施形態では、保持室１８を管路形状に形成して第１の空間１７と第２の空間２３とを広範に接続しているため、第２の空間２３で発生した蒸気泡を第１の空間１７に直接抜くことができる。その際、保持室１８の断面を円形にしたことにより、保持室１８の断面が四角形等の場合に比べて、保持室１８の下面付近における冷却水Ｗ１の流れの抵抗を低減することができる。したがって、第１の空間１７及び第２の空間２３内の冷却水Ｗ１の対流をより促進することができる。 In the present embodiment, since the holding chamber 18 is formed in a pipe shape and the first space 17 and the second space 23 are widely connected, the vapor bubbles generated in the second space 23 are removed. The first space 17 can be directly pulled out. At this time, by making the cross section of the holding chamber 18 circular, the resistance of the flow of the cooling water W1 in the vicinity of the lower surface of the holding chamber 18 can be reduced as compared with the case where the cross section of the holding chamber 18 is a square or the like. Therefore, the convection of the cooling water W1 in the first space 17 and the second space 23 can be further promoted.

以上より、炉心溶融物４の冷却性をより向上させ格納容器５０の床部２への炉心溶融物４の侵食をより抑制することができる。 As described above, the cooling property of the core melt 4 can be further improved, and the erosion of the core melt 4 to the floor portion 2 of the containment vessel 50 can be further suppressed.

＜その他＞
本発明は上記した実施例に限定されるものではなく、様々な変形例が含まれる。例えば、上記した実施例は本発明を分かりやすく説明するために詳細に説明したものであり、必ずしも説明した全ての構成を備えるものに限定されるものではない。また、ある実施例の構成の一部を他の実施例の構成に置き換えることが可能であり、また、ある実施例の構成に他の実施例の構成を加えることも可能である。また、各実施例の構成の一部について、他の構成の追加・削除・置換をすることが可能である。 <Others>
The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

各実施形態において、炉心溶融物導入流路１５の断面が円形状の場合を例に挙げて説明した。しかしながら、本発明の本質的効果は、炉心溶融物の冷却性の向上により原子炉格納容器の床部への炉心溶融物の侵食を抑制することができるコンパクトな床材ユニットを提供することであり、この本質的効果を得る限りにおいては炉心溶融物導入流路１５の断面形状は限定されない。例えば、炉心溶融物導入流路１５の断面を矩形状としても良い。 In each embodiment, the case where the core melt introduction flow path 15 has a circular cross section has been described as an example. However, the essential effect of the present invention is to provide a compact flooring unit that can suppress the erosion of the core melt to the floor of the reactor containment vessel by improving the cooling property of the core melt. As long as this essential effect is obtained, the cross-sectional shape of the core melt introduction flow path 15 is not limited. For example, the cross section of the core melt introduction flow path 15 may be rectangular.

また、各実施形態において、複数のセグメント６ａ，６ｂ・・・を互いに離間して配置して床材ユニット６を形成した場合を例示している。しかしながら、本発明の本質的効果を得る限りにおいては床材ユニット６は上述の構成に限定されない。例えば、複数のセグメント６ａ，６ｂ・・・を搬入し、その後溶接等により一体構造としても良く、複数のセグメント６ａ，６ｂ・・・を予め溶接等により一体構造とし、その後搬入しても良い。 Moreover, in each embodiment, the case where the flooring unit 6 is formed by arranging a plurality of segments 6a, 6b,. However, the flooring unit 6 is not limited to the above configuration as long as the essential effects of the present invention are obtained. For example, a plurality of segments 6a, 6b... May be carried in, and then integrated by welding or the like, or a plurality of segments 6a, 6b.

また、各実施形態において、第１伝熱板７に８つの蒸気抜き孔２０を形成した場合を例に挙げて説明した。しかしながら、本発明の本質的効果を得る限りにおいては、第１伝熱板７に形成される蒸気抜き孔２０の数は限定されない。例えば、９つ以上又は７つ以下の蒸気抜き孔２０を形成してもよい。 Moreover, in each embodiment, the case where the eight steam vent holes 20 were formed in the 1st heat exchanger plate 7 was mentioned as an example, and was demonstrated. However, the number of the steam vent holes 20 formed in the first heat transfer plate 7 is not limited as long as the essential effects of the present invention are obtained. For example, nine or more or seven or less steam vent holes 20 may be formed.

また、各実施形態において、複数のセグメント６ａ，６ｂ・・・がそれぞれ１つの導入流路１５を備えた場合を例に挙げて説明した。しかしながら、本発明の本質的効果を得る限りにおいては、複数のセグメント６ａ，６ｂ・・・がそれぞれ複数の導入流路１５を備えても良い。 In each embodiment, the case where each of the plurality of segments 6a, 6b,... However, as long as the essential effects of the present invention are obtained, the plurality of segments 6a, 6b,...

また、各実施形態においては、床材ユニット６を複数のセグメントの集合体としたのでセグメントの数だけ保持室１８を備える場合を例に挙げて説明したが、例えば床材ユニット自体を１つのセグメントと同等の構成として保持室１８を１つだけ備えた構成とすることもできる。 Moreover, in each embodiment, since the flooring unit 6 was an aggregate of a plurality of segments, the case where the holding chambers 18 are provided as many as the number of segments has been described as an example. For example, the flooring unit itself is a single segment. It is also possible to adopt a configuration in which only one holding chamber 18 is provided as an equivalent configuration.

また、本発明に係る床材ユニットは、沸騰水型原子炉、加圧水型原子炉等の軽水炉を始めとする各種原子炉の格納容器に適用可能である。 Moreover, the flooring unit according to the present invention is applicable to containment vessels of various nuclear reactors including light water reactors such as boiling water reactors and pressurized water reactors.

４炉心溶融物
６床材ユニット
７第１伝熱板
１３第２伝熱板
１４第３伝熱板
１５炉心溶融物導入流路
１７第１の冷却水対流空間（第１の空間）
１８炉心溶融物保持室
５０原子炉格納容器（格納容器） 4 Core melt 6 Floor material unit 7 1st heat transfer plate 13 2nd heat transfer plate 14 3rd heat transfer plate 15 Core melt introduction flow path 17 1st cooling water convection space (1st space)
18 Core melt holding chamber 50 Reactor containment vessel (containment vessel)

Claims

In the flooring unit placed on the floor of the reactor containment vessel,
A first heat transfer plate that receives the core melt falling toward the floor;
The ceiling surface and the bottom surface are the second heat transfer plate and the third heat transfer plate, respectively, and at least one core melt is opposed to the second heat transfer plate on the lower side of the first heat transfer plate with the first space interposed therebetween. A holding room,
A core melt introduction flow path connecting the introduction hole provided in the first heat transfer plate and the core melt holding chamber;
And a spacer to secure a second space between the floor of the reactor containment vessel and the third heat transfer plate,
A flooring unit comprising a steam vent pipe communicating the first space and the second space.

In the flooring unit placed on the floor of the reactor containment vessel,
A first heat transfer plate that receives the core melt falling toward the floor;
The ceiling surface and the bottom surface are the second heat transfer plate and the third heat transfer plate, respectively, and at least one core melt is opposed to the second heat transfer plate on the lower side of the first heat transfer plate with the first space interposed therebetween. A holding room,
A core melt introduction flow path connecting the introduction hole provided in the first heat transfer plate and the core melt holding chamber;
An assembly of a plurality of segments each having the first heat transfer plate, the core melt holding chamber, and the core melt introduction flow path;
The said segment is provided with the notch formed in the edge part of the said 1st heat exchanger plate, respectively, The flooring unit characterized by the above-mentioned.

In the flooring unit according to claim 1 or 2 ,
A flooring unit, comprising a steam vent hole formed in the first heat transfer plate and communicating the space above the first heat transfer plate and the first space.

In the flooring unit according to claim 1 or 2 ,
A flooring unit, comprising a gas vent hole formed in the second heat transfer plate and communicating between the first space and the inside of the core melt holding chamber.

In the flooring unit according to claim 1 or 2 ,
The core melt introduction flow path has a flow path width that expands downward.

In the flooring unit according to claim 2 ,
A fourth heat transfer plate facing the second space on the lower side of the third heat transfer plate;
And a spacer to secure a third space between the floor of the reactor containment vessel and the fourth heat transfer plate,
The core melt holding chamber is formed in a pipe shape, and the first space and the second space are connected ,
The aggregate of the plurality of segments further includes the spacer for securing the fourth heat transfer plate and the third space, respectively .

In the flooring unit according to claim 1 or 2 ,
The flooring unit, wherein the first heat transfer plate is formed to be inclined downward toward the introduction hole.

In the flooring unit according to claim 1,
It is an assembly of a plurality of segments each having the first heat transfer plate, the core melt holding chamber, the core melt introduction channel , the spacer for securing the second space, and the steam vent pipe. A flooring unit characterized by

The flooring unit according to claim 8,
The said segment is provided with the notch formed in the edge part of the said 1st heat exchanger plate, respectively, The flooring unit characterized by the above-mentioned.

A reactor containment vessel comprising the flooring unit according to any one of claims 1 to 9.