JPS5922197B2 - Reactor safety valve blow-down parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blowdown member for a safety valve of a nuclear reactor, the first end of which is connected to the safety valve, and the second end of which is connected to a blowdown member within a condensate pool. The first and second discharge holes are arranged so as to be located below the water level, and the first and second discharge holes are located in the part that is placed underwater.
It pertains to those for which a group of .

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved blowdown member which is capable of significantly reducing the stresses created in the condensate pool when the safety valve opens, ie during the initial outflow phase.

A non-condensable gas, e.g. air, which is trapped above the water level of the condensate pool in a discharge member connected to the safety valve, is suddenly compressed and the next moment is discharged into the water at atmospheric pressure.

As a result, strong pressure pulsations occur in the condensate pool.

A known blow-down device is described in German patent application no.
April 10, 1973 - April 13, 1973.

According to the German patent application, a tube is used as the downflow member, the lower end of the limb is inserted in a vertical direction, and a plurality of radially oriented holes are provided near the insertion end face. known to be concentrated.

The patent application specification further discloses a blowdown pipe having two groups of discharge holes oriented in the axial direction, the two groups being arranged with a distance in the axial direction from each other. has been done.

As a result of extensive tests carried out in the context of research and development prior to the present invention, the amplitude of the pressure pulsations generated in the corresponding condensation pool due to the initial outflow of non-condensable gas upon the opening of the reactor safety valve was determined. A construction principle was established that involved a considerable reduction in

In the evacuation device according to the invention, the gas to be ejected is distributed in a manner known per se between two independent groups of ejection holes, so that two main evacuation streams are formed, which flows:
Each is composed of a plurality of small exhaust streams, the two main exhaust streams forming two large gas clouds.

In the device according to the invention, a relatively large phase difference between the pressure pulsations of the two gas clouds is targeted, which usually requires that the two groups of outlet holes be arranged at a considerable distance from each other. It means not to be.

At the same time, combining two gas clouds,
Or at least it is necessary that they are formed so close to each other that a pressure equilibrium between them is obtained with little disturbance by intermediate water.

The experimental test found that the successful coordination between the two gas clouds in connection with vibration isolation depends significantly on the manner in which the discharge holes for the gas flowing into the condensate pool are oriented with respect to each other. It was done.

Tests have shown that the two gas clouds must be oriented such that the vectors of the two groups of discharge velocities intersect each other to a significant extent.

ffpAccording to the invention, the first end is connected to the safety valve and the second end is arranged below the water level in the condensation pool, and the first end is connected to the submerged portion. and a second group of discharge holes, the first group of discharge holes being disposed within a first surface area and the second group of discharge holes being disposed within a second surface area. and said first
A blowdown member for a safety valve of a nuclear reactor, wherein a surface area of the discharge hole is separated from the second surface area, wherein the discharge holes of the first and second groups are arranged in the water of the condensate pool. Designed and arranged so that the velocity vector of the medium blown out from the first group of discharge holes substantially intersects the velocity vector of the medium blown out from the second group of discharge holes. Provided is a blowdown member characterized by the following.

The invention will now be further explained by way of examples with reference to the accompanying drawings.

In FIGS. 1 and 7, number 1 indicates the reactor vessel of a boiling water reactor.

A plurality of steam conduits 2 extend from the reactor vessel 1, and each steam conduit 2 is provided with a safety valve 3.

The purpose of the downflow member 4 is to connect the outlet of the safety valve 3 to the condensate pool 5.

The water level of the pool is indicated by a triangle 6 in the drawing.

The blowdown member 4/ shown in FIGS. 2, 3 and 4 has a tube 7 having a length of at least 2 m, the lower end of the limb tube 7 having a substantially radial direction. A group of exit holes 8 are provided which are oriented.

The end plate 9 welded to the tube 7 has at least one axially oriented outlet hole.

The total hole area of the end plate 9 is 25% or less, preferably 10% or less of the pipe internal cross-sectional area.

Between said group of outlet holes 8 and the water level, the pipe wall has a plurality of holes 10 arranged at the same height, these holes 10
cooperate with corresponding axial passages 11 provided in the ring 12 surrounding the tube 7 to define a plurality of substantially vertically oriented downward discharge openings.

In normal operation, the tube 7 is primarily filled with gas, for example air, above the water level 6.

When the safety valve 3 opens, gas is initially forced out through the passage 11 and after some time through the outlet hole 8.

The direction of gas outflow is indicated by arrows 13 and 14 in FIG.

If a suitable velocity is chosen, the velocity vectors of the first group will intersect the velocity vectors of the second group by a predominant number (perhaps more than 80%).

The distance between the upper and lower groups of discharge holes is such that the time difference between the start times of two discharge flows is 25 to 75 of the period of other basic pressure oscillations.
selected to make up %.

The optimum damping effect is achieved at a time difference slightly less than 50 times the period.

The blowdown member 4'' shown in FIGS. 5 and 6 has a vertical tube 15, the lower end of which is passed through the top opening of a hollow body 16 welded to the limb tube 15. ing.

The main body 16 has an upper discharge port 17 and a lower discharge port 18 formed therein.

The direction of the corresponding delivery velocity is indicated by arrows 19 and 20.

The hollow body 16 has a first end wall 21 and a second end wall 22, through which the tube 15 passes in an airtight manner.

The two end walls 21 and 22 each have a cylindrical side wall 23.
．． 24, and the side walls 23 and 24 are connected to each other by a plurality of connecting pieces 25, thereby defining a substantially vertically oriented passageway.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the manner in which the blowdown device according to the invention is arranged with respect to the components connected thereto; FIG. 2 is a side view of an embodiment of the blowdown device according to the invention Figure; Figure 3 is a cross-sectional view taken along line ■-■ in Figure 2; Figure 4 is a cross-sectional view taken along line IV-IV in Figure 3; Figure 5 is a cross-sectional view taken along line IV--IV in Figure 3; FIG. 6 is a longitudinal sectional view of the second embodiment of the blowdown device taken along the line V-V in FIG. 6; FIG. 6 is a cross-sectional view taken along the line ■-■ in FIG. 5; FIG. 7 is a schematic diagram showing an embodiment of an alternative arrangement to that shown in FIG. On the drawing, 1 is the "reactor vessel"; 3 is the "safety valve"; 4 is "the reactor vessel";
5 is the “condensation pool”; 6 is the “water level j; 7
, 15 is "pipe j; 4', 4" is "downflow member"; s, i
i is "discharge hole"; 9 is "end plate"; 16 is "main body j; 2
1.22 is “end wall j; 23°24 is “side wall”; 25 is “
18 indicates the "lower discharge port", respectively.

Claims (1)

[Claims] 1. A blow-down member for a reactor safety valve, which includes a first end connected to the safety valve and a second end below the water surface of the condensation pool 5.
The part having an end portion and located below the water surface is provided with a second group of discharge holes, the first group of discharge holes are arranged in the first surface area, and the second group of discharge holes are arranged in a second surface area. in a blowdown member disposed in a surface area of the outlet, the first surface area being separated from a second surface area, the first flow constituting a large portion of the medium flowing out of the first group of discharge holes; is close to a second stream forming a large portion of the medium flowing out of the second group of discharge holes, and in the water of the condensation pool, at the stage when the first stream is blown out of the first group of discharge holes. velocity vector 1
4.19 is characterized in that the discharge holes are designed and arranged so as to substantially intersect the velocity vector of the first flow when it is blown out from the second group of discharge holes. Element. 2. In the blow-down member for a nuclear reactor safety valve as set forth in claim 1, the portion located in the water consists of a tube 7, and a stopper or a strong contraction body is attached to the end of the tube 7. are arranged, and the first group of discharge holes is connected to the plug body 9.
consisting of a plurality of substantially radially oriented discharge holes 8 arranged in the vicinity of the pipe wall, while
A blow-down member characterized in that the second group of discharge holes 11 are provided in a tube wall and are oriented substantially in the longitudinal direction of the tube. 3. In the blow-down member for a nuclear reactor safety valve according to claim 1, the pipe 15 and the first pipe arranged below the water surface are provided.
a hollow body 16 having an end wall 21 and a second end wall 22;
The first and second end walls are directly connected to the first side wall 23 and the second side wall 24, and the first and second side walls 2
3.24 are fixed in coaxial relation to each other by a plurality of radially disposed connecting pieces 25 extending from the first side wall 23, and the tube 15 is connected to the first and second end walls 23.
1.22, the first group of discharge holes are disposed airtightly passing through the first end wall 21 such that the insertion tube length is greater than l/2 of the distance between 23 and are oriented substantially radially with respect to the longitudinal direction of the tube 15, while the second group of discharge holes are formed in a plurality of passages 18 formed between the connecting pieces 25. A blowdown member characterized by comprising: