JPS6136960Y2

JPS6136960Y2 -

Info

Publication number: JPS6136960Y2
Application number: JP1980044243U
Authority: JP
Priority date: 1980-03-31
Filing date: 1980-03-31
Publication date: 1986-10-25
Also published as: JPS56144396U

Description

[Detailed explanation of the idea]

本考案は、蒸気排出装置に係り、特に、リリー
フベント管を有する蒸気排出装置に関するもので
ある。従来のものを示す第１図において、１は圧力炉
圧力容器、２は原子炉圧力容器１に連通する主蒸
気管、４はリリーフ弁３を備えたリリーフベント
管で、第２図に示す如く主蒸気管２から分岐して
おり、リリーフベント管管４の他端は圧力抑制室
５内の冷却水であるプール６の水中に開口してい
る。原子炉停止及び原子炉事故時において、原子炉
圧力容器１内の圧力を下げるためにリリーフ弁３
を開き蒸気をプール水６中に放出する。この場合
にプール水６中に気泡圧力脈動を生ずる。第３図
において、イに示すようにリリーフベント管４内
は、リリーフ弁３が開く前は、空気部分４ａと水
面位置以下の水柱４ｂとからなつている。リリー
フ弁３を開くと原子炉圧力容器１内の蒸気４ｃが
リリーフベント管４内に放出され、管内の空気部
分４ａを圧縮しながら水柱４ｂを下方に押しや
る。蒸気４ｃは音速で放出されるので、空気部分
４ａと蒸気４ｃは殆んど混合せず、空気部分４ａ
はリリーフベント管４出口から気泡となつてプー
ル６の水中に放出される。第３図ロ，ハ，ニはこ
の状態を示す。この間、空気部分４ａは20〜30Kg／cm²ｇに加圧
されており、プール水６中へ放出とともに減圧し
急膨張を行い空気泡４a′を生ずる。気泡膨張の過
程においては、押しやられたプール水６の慣性
で、気圧の圧力がプール水６の圧力まで下がつて
も、更に気泡は膨張し気泡圧力は負圧になる。慣
性が無くなると、気泡の負圧により周囲のプール
水６が引き寄せられ、プール水６の慣性により気
泡は圧縮され気泡の圧力は放出時の圧力よりも高
くなる。空気泡４a′の圧縮、膨張の過程を第４図
に示す。第４図に示すイ，ロ，ハおよびニは第３
図のイ，ロ，ハおよびニにそれぞれ対応する状態
を示す。このような空気泡４a′の脈動は、気泡が
プール６水面に到達するまで続く。この圧力脈動
は水中波となり、プール６水中の構造物に加わ
り、動的な荷重として作用する。米国などの実機
プラントでの測定結果によると、この水中波は、
５〜15Hzで正圧３Kg／cm²ｇ、負圧−1.5Kg／cm²ｇ
程度になり、気泡が水面で破裂するまで約１秒続
く。また、リリーフ弁３作動時に高圧の空気部分
４ａによりリリーフベント管４内の水柱４ｂが高
速で排出される。この水流による水ジエツト力
が、第３図の矢印４ｄのようにダイナミツクな力
として圧力抑制室５の底に加わり、原子炉格納容
器、特に圧力抑制室５を損傷させるおそれがあ
る。このようなリリーフ弁３の作動による繰り返え
し振動は、プラント寿命中4000〜5000回となり、
(1)気泡圧力脈動、(2)水ジエツト力により水面下の
構造物および圧力抑制室５底部に疲労応力を加え
るので、圧力抑制室の損傷の恐れが生じる。本考案の目的は、リリーフベント管を水浸長さ
の異なる複数本の排気管に分岐することによつ
て、かかる圧力脈動の荷重を緩和する管蒸気排出
装置を供給することにある。本考案は、圧力抑制室に発生する圧力脈動の荷
重が緩和されるように、該リリーフベント管を水
浸部長さの異なる複数本の排気管に分岐し、各分
岐管の蒸気凝縮能力の合計が値を満足するように
各分岐管の蒸気流路面積を設定する。第５図および第６図に、本考案の実施例を示
す。本考案は、リリーフ弁に接続されるリリーフベ
ント管４にヘツダ７を取付けて左右に分岐し、更
に、ヘツダ７に各々のプール水６内での水浸部長
が複数の異なる排気管８を設置する。各々の排気
管８の水浸部長さはリリーフベント管４に対して
左右対称であり、且つ中心部の排気管８の水浸部
長が最小である。更に、各々の排気管８の流路面積は左右対称で
且つリリーフベント管４の流路面積より狭くなつ
ているが、一方各々の排気管８の流路面積の合計
値は広い。更に中心部程流路面積は狭くなつてい
る。第７図に、本実施例の具体的な寸法関係を示
す。すべての排気管８の流路断面積を合計した流
路断面積A₁は、リリーフベント管４の流路断面
積A₀の２倍である。流路断面積A₁は、
The present invention relates to a steam exhaust device, and more particularly to a steam exhaust device having a relief vent pipe. In Fig. 1 showing a conventional system, 1 is a pressure reactor pressure vessel, 2 is a main steam pipe communicating with the reactor pressure vessel 1, and 4 is a relief vent pipe equipped with a relief valve 3, as shown in Fig. 2. It branches from the main steam pipe 2, and the other end of the relief vent pipe 4 opens into the water of the pool 6, which is the cooling water in the pressure suppression chamber 5. A relief valve 3 is provided to reduce the pressure inside the reactor pressure vessel 1 in the event of reactor shutdown or reactor accident.
is opened to release steam into the pool water 6. In this case, bubble pressure pulsations occur in the pool water 6. In FIG. 3, as shown in A, the interior of the relief vent pipe 4, before the relief valve 3 opens, consists of an air portion 4a and a water column 4b below the water surface level. When the relief valve 3 is opened, the steam 4c in the reactor pressure vessel 1 is released into the relief vent pipe 4, compressing the air portion 4a inside the pipe and pushing the water column 4b downward. Since the steam 4c is released at the speed of sound, the air portion 4a and the steam 4c hardly mix, and the air portion 4a
is released into the water of the pool 6 from the outlet of the relief vent pipe 4 in the form of bubbles. Figure 3 B, C and D show this state. During this time, the air portion 4a is pressurized to 20 to 30 kg/cm ² g, and as it is discharged into the pool water 6, the pressure is reduced and the air portion 4a rapidly expands to produce air bubbles 4a'. In the process of bubble expansion, even if the atmospheric pressure drops to the pressure of the pool water 6 due to the inertia of the pushed pool water 6, the bubble expands further and the bubble pressure becomes negative pressure. When the inertia disappears, the surrounding pool water 6 is attracted by the negative pressure of the bubbles, the inertia of the pool water 6 compresses the bubbles, and the pressure of the bubbles becomes higher than the pressure at the time of release. FIG. 4 shows the process of compression and expansion of the air bubble 4a'. A, B, C and D shown in Figure 4 are the third
The states corresponding to A, B, C, and D in the figure are shown. Such pulsation of the air bubbles 4a' continues until the air bubbles reach the water surface of the pool 6. This pressure pulsation becomes an underwater wave and is added to the underwater structure of the pool 6, acting as a dynamic load. According to measurement results at actual plants in the United States and other countries, these underwater waves are
Positive pressure 3Kg/cm ² g, negative pressure -1.5Kg/cm ² g at 5-15Hz
It lasts about 1 second until the bubble bursts on the water surface. Furthermore, when the relief valve 3 is activated, the water column 4b inside the relief vent pipe 4 is discharged at high speed by the high-pressure air portion 4a. The water jet force caused by this water flow is applied to the bottom of the pressure suppression chamber 5 as a dynamic force as indicated by the arrow 4d in FIG. 3, and there is a risk of damaging the reactor containment vessel, especially the pressure suppression chamber 5. The repeated vibration due to the operation of the relief valve 3 will be 4000 to 5000 times during the life of the plant.
(1) Bubble pressure pulsations and (2) water jet force apply fatigue stress to structures below the water surface and the bottom of the pressure suppression chamber 5, which may cause damage to the pressure suppression chamber. An object of the present invention is to provide a pipe steam exhaust device that relieves the load of such pressure pulsations by branching a relief vent pipe into a plurality of exhaust pipes having different water immersion lengths. In this invention, the relief vent pipe is branched into multiple exhaust pipes with different water immersion lengths in order to alleviate the load of pressure pulsations occurring in the pressure suppression chamber, and the total steam condensation capacity of each branch pipe is The steam flow path area of each branch pipe is set so that the value is satisfied. An embodiment of the present invention is shown in FIGS. 5 and 6. In the present invention, a header 7 is attached to the relief vent pipe 4 connected to the relief valve, and the header 7 is branched to the left and right, and a plurality of exhaust pipes 8 are installed in the header 7, each having a different length of water immersion in the pool water 6. do. The water immersion length of each exhaust pipe 8 is symmetrical with respect to the relief vent pipe 4, and the water immersion length of the central exhaust pipe 8 is the smallest. Further, the passage area of each exhaust pipe 8 is symmetrical and narrower than the passage area of the relief vent pipe 4, but on the other hand, the total value of the passage area of each exhaust pipe 8 is wide. Furthermore, the flow path area becomes narrower toward the center. FIG. 7 shows the specific dimensional relationship of this example. The flow path cross-sectional area A ₁ , which is the sum of the flow path cross-sectional areas of all the exhaust pipes 8 , is twice the flow path cross-sectional area A ₀ of the relief vent pipe 4 . The flow path cross-sectional area _A1 is

【式】で表わされる。a₁は、各排気管８の流路断面積である。従来の水浸長さをh₀とする
と、h₁はh₁＝h₀／２で表わされる。以上より、以下の効果がある。 (1) 蒸気凝縮量低減に伴う荷重低減第８図は、水浸部長ｈ及び流路面積Ａに対す
る蒸気放出時にプール水内に発生する荷重と蒸
気凝縮の関係を示す。特性，，および
と後者に行くほど、A₁が大きくなり、特性
はA₁＝2A₀における特性である。図から分るように、水浸部長が短い程、蒸気
凝縮量及び荷重が減少する。一方、同一水浸部
長においては、流路面積が小さい程、蒸気凝縮
量及び荷重が減少する。従つて、流路抵抗の小さい中心部の排気管８
程、水浸部長を短く、且つ流路面積を狭くする
ことにより、蒸気凝縮量は低減し、これに伴つ
て発生する荷重を低減できる。例えば、第８図
より流路面積を従来の２倍、ベント水浸長さを
従来の１／２にすると荷重は約３割に低減でき
る。Ｐ点が従来例、Ｑ点が本実施例を示す。 (2) 非凝縮性ガス気泡形成に伴う荷動低減リリーフ弁３の作動開始によりプール水中で
形成される非凝縮性ガスの気泡半径の大きさ
は、排気管８の水浸長が短い程小さくなる。従
つて、気泡に伴う荷重も水浸長が短い程低くな
り、その関係は次式のようになる。Ｆ∝ｈただし、Ｆは荷重、ｈは排気管の水浸長さで
ある。また、第９図に、第７図のような構造で、水
浸長が、h₀／２及びh₀／４の排気管８を有する
リリーフベント管による荷重の変化図中の記号
を次に示す。h₀は従来の水浸長さである。 (a)は水浸長h₁の排気管８から気泡が放出され
た時の荷重の変化、 (b)は水浸長h₁／２の排気管８から気泡が放出
された時の荷重の変化を示している。 (c)は(a)＋(c)の荷重の変化である。 (d)は従来の特性である。この図から、まず水浸長h₁／２の排気管８か
ら非凝縮性ガスが放出されることに伴う荷重(a)
が発生し、次に遅れてから、水浸長ｈの排気管
８から放出される非凝縮性ガスに伴う荷重(a)が
発生する。これら２つの荷重を加えた荷重(c)
は、従来の荷重より低減することが判る。本考案によれば、リリーフ弁開放時において、
高圧の空気を水浸長が異なるベント分岐管から順
次ブール水中に放出できるので、空気脈動振動を
効果的に低減できる。It is represented by [Formula]. a ₁ is the flow path cross-sectional area of each exhaust pipe 8 . When the conventional water immersion length is h ₀ , h ₁ is expressed as h ₁ =h ₀ /2. From the above, there are the following effects. (1) Load reduction due to reduction in amount of steam condensation Figure 8 shows the relationship between the load generated in the pool water when steam is released and the steam condensation for the water immersion length h and the flow path area A. As the characteristics , , and the latter, A ₁ becomes larger, and the characteristics are those when A ₁ =2A ₀ . As can be seen from the figure, the shorter the water immersion section, the lower the amount of steam condensation and the load. On the other hand, in the same water-immersed section, the smaller the flow path area, the smaller the amount of steam condensation and the load. Therefore, the central exhaust pipe 8 with low flow path resistance
By shortening the water immersion section and narrowing the flow path area, the amount of steam condensation can be reduced, and the load generated accordingly can be reduced. For example, as shown in FIG. 8, if the flow path area is doubled and the vent water immersion length is made half of the conventional length, the load can be reduced to about 30%. Point P indicates the conventional example, and point Q indicates the present embodiment. (2) Reducing load movement due to the formation of non-condensable gas bubbles The radius of the non-condensable gas bubbles formed in the pool water when the relief valve 3 starts operating becomes smaller as the water immersion length of the exhaust pipe 8 becomes shorter. Become. Therefore, the load associated with bubbles also decreases as the water immersion length becomes shorter, and the relationship is as shown in the following equation. F∝h where F is the load and h is the water immersion length of the exhaust pipe. In addition, in Fig. 9, the symbols in the diagram of the change in load due to the relief vent pipe having the structure as shown in Fig. 7 and the exhaust pipe 8 with water immersion lengths of h ₀ /2 and h ₀ /4 are as follows. show. h ₀ is the conventional water immersion length. (a) shows the change in load when air bubbles are released from the exhaust pipe 8 with water immersion length h ₁ , and (b) shows the change in load when air bubbles are released from the exhaust pipe 8 with water immersion length h _1/2 . It shows change. (c) is the change in load of (a) + (c). (d) is the conventional characteristic. From this figure, first, the load (a) associated with the release of non-condensable gas from the exhaust pipe 8 with water immersion length h ₁ /2
occurs, and then, after a delay, the load (a) associated with the non-condensable gas discharged from the exhaust pipe 8 with the water immersion length h occurs. Load (c) that is the sum of these two loads
It can be seen that the load is reduced compared to the conventional load. According to the present invention, when the relief valve is opened,
Since high-pressure air can be sequentially discharged into the boule water from vent branch pipes with different water immersion lengths, air pulsation vibration can be effectively reduced.

[Brief explanation of the drawing]

第１図は沸謄水型原子炉の原子炉格納容器の外
観図、第２図は従来のリリーフベント管の構造
図、第３図は空気圧力脈動振動のプロセスを示す
もので、イ，ロ，ハおよびニの順でリリーフベン
ト管内の空気および蒸気の放出が進行していくこ
とを示す説明図、第４図は圧力抑制室内の空気泡
圧力変動を示す特性図、第５図は本考案の実施例
の斜視図、第６図は第５図に示す実施例の側面
図、第７図は第５図に示す実施例の寸法関係を示
す説明図、第８図は排気管の水浸長さによる発生
荷重の変化を示す特性図、第９図は本考案による
効果を示す特性図である。１……原子炉圧力容器、４……リリーフベント
管、５……圧力抑制室、６……プール水、８……
排気管。 Figure 1 is an external view of the reactor containment vessel of a boiling water reactor, Figure 2 is a structural diagram of a conventional relief vent pipe, and Figure 3 shows the process of air pressure pulsation vibration. , C, and D are explanatory diagrams showing that the release of air and steam inside the relief vent pipe progresses in the order shown. Figure 4 is a characteristic diagram showing air bubble pressure fluctuations in the pressure suppression chamber. Figure 5 is a diagram showing the progress of the release of air and steam in the relief vent pipe in the order of FIG. 6 is a side view of the embodiment shown in FIG. 5, FIG. 7 is an explanatory diagram showing the dimensional relationship of the embodiment shown in FIG. FIG. 9 is a characteristic diagram showing the change in generated load depending on the length. FIG. 9 is a characteristic diagram showing the effects of the present invention. 1... Reactor pressure vessel, 4... Relief vent pipe, 5... Pressure suppression chamber, 6... Pool water, 8...
Exhaust pipe.

Claims

[Claims for Utility Model Registration] 1. In a steam exhaust device having a relief vent pipe that guides steam in a reactor pressure vessel into a pressure suppression chamber filled with coolant, the liquid level of the coolant in the pressure suppression chamber is lower than the liquid level of the coolant in the pressure suppression chamber. The header in the space above,
attached to the relief vent pipe, the discharge pipe is provided in the header so as to be symmetrical with respect to the relief vent pipe within the space within the pressure suppression chamber, and only facing downward, the closer to the relief vent pipe; A steam exhaust device characterized in that the length of the exhaust pipe is shortened and the flow path area thereof is reduced. 2. The steam exhaust device according to claim 1, wherein the length and flow path area of each of the exhaust pipes are symmetrical with respect to the relief vent pipe.