JP4202947B2 - Steam dryer for boiling water reactor - Google Patents

Description

  The present invention relates to a steam dryer used in a boiling water reactor, and more particularly to a steam dryer that is less prone to vibration due to the flow of return water from a steam separator.

  FIG. 10 shows the appearance of a normal steam dryer used in a boiling water reactor. The steam dryer is composed of an upper dryer bank 10 and an upper ring 4 that supports it, a skirt 1 that separates the steam flow from the core and the steam flow that exits the steam dryer, and a lower ring 3 that supports the skirt 1. ing. Further, a drain channel 2 is provided on the outer surface of the skirt 1 in order to discharge drain water from the dryer bank. The steam dryer is disposed in the reactor pressure vessel so as to surround the top and the periphery of the steam separator.

  FIG. 11 shows a state of fluid flow in the skirt 1 of the steam dryer. In order to separate the moisture from the vapor containing droplets, the water which has become a mixture of liquid and gas after boiling in the reactor core is separated into the vapor stream 7 and the return water stream 6 by the steam separator 8. The subsequent steam flow 7 is directed to the dryer bank 10. In the dryer bank 10, moisture is separated by a perforated plate or a droplet impingement corrugated plate, and this is discharged as drain water from a steam dryer to reactor water. Specifically, drain water is led from a drain pipe 5 inside the skirt 1 of the steam dryer to a drain channel 2 inside or outside the skirt 1, and is discharged to the outside of the skirt 1 through the drain channel 2.

  FIG. 12 shows an enlarged view of the vicinity of the drain channel 2. The drain channel 2 is made of a metal plate that is relatively thinner than the thickness of the skirt 1 with respect to the cylindrical skirt 1, and bends both side ends in a 90-degree direction with curvature, and sets both side ends to the outer surface of the skirt 1. It is constituted by welding the upper end 5 to the upper ring 4 located at the upper part of the skirt 1.

The drain channel 2 of the boiling water reactor steam dryer vibrates due to pressure fluctuations inside and outside the skirt 1 of the steam dryer, and vibration stress is generated in the vicinity of the weld. In the conventional steam dryer, an example in which a fatigue crack is generated near the welded portion of the drain channel 2 due to this vibration stress has been reported. (For example, press release on September 18, 1989, Ministry of International Trade and Industry, Nuclear Power Management Office: "Troubles discovered during periodic inspection of Fukushima Daiichi Nuclear Power Station Unit 1 of TEPCO", 1993 News release dated November 22, 2011: “Causes and countermeasures for troubles discovered during the periodic inspection of TEPCO Fukushima Daini Nuclear Power Station Unit 1”.
As shown in FIG. 11, the return water flow 6 from the steam separator 8 collides with the lower end of the skirt 1 and the lower ring 3 positioned below the skirt 1 and flows out of the skirt 1. This causes the pressure difference between the inside and outside of the skirt 1 to fluctuate.

  On the other hand, as can be seen from the cross section of the skirt 1 shown in FIG. 13A, the drain channel 2 is welded to the outer periphery of the skirt 1. As shown in FIGS. 13 (b) and 13 (c), the skirt 1 causes oval vibration, and the drain channel 2 also vibrates in a manner induced by this. Such vibration has the maximum stress amplitude due to stress concentration at the welded portion between the drain channel 2 and the skirt 1 as shown in FIG.

  For this reason, it is necessary to weld the connecting portion between the weld metal 15 and the drain channel 2 and the skirt 1 so as to be smooth as shown in FIGS. 14A to 14C to reduce stress concentration. However, as can be seen from FIG. 12, the space between the lower end of the drain channel 2 and the upper end of the lower ring 3 is narrow. Therefore, when the lower end of the drain channel 2 is welded to the skirt 1, it is necessary to be skilled in welding in such a smooth shape. For example, there is a possibility that smoothness does not occur between the skirt 1 and the weld metal 15 as shown in FIG. 15A, or smoothness between the drain channel 2 and the weld metal 15 as shown in FIG. 15B. There is. Since such a shape leads to an increase in stress concentration, it contributes to fatigue accumulation.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a boiling water reactor steam dryer that realizes reduction of vibration and reduction of stress concentration at a weld.

  The present invention is directed to the above object, and the invention according to claim 1 is a boiling water reactor steam dryer disposed so as to cover a steam separator in a reactor pressure vessel. A dryer bank that is disposed above the steam separator to separate moisture in the steam, a cylindrical skirt that is connected to the dryer bank and that is open at the bottom, and the moisture separated by the dryer bank is Drain means for guiding the outside of the skirt, and a lower ring connected to the lower end of the skirt, and the lower end of the lower ring is positioned below the water outlet separated by the steam separator And the diameter of the inner surface of the said lower ring is comprised so that it may become large toward a lower end, It is characterized by the above-mentioned.

  The invention according to claim 2 is a boiling water reactor steam dryer disposed so as to cover the steam separator in the reactor pressure vessel, and is disposed above the steam separator. A dryer bank that separates moisture in the steam, a cylindrical skirt that is connected to the dryer bank and that is open at the bottom, and drain means that guides the moisture separated by the dryer bank to the outside of the skirt. And the skirt has a drain hole penetrating the skirt at a position that becomes a node of the oval vibration.

  The invention described in claim 3 is a boiling water reactor steam dryer disposed so as to cover the steam separator in the reactor pressure vessel, and is disposed above the steam separator. A dryer bank that separates moisture in the steam, a cylindrical skirt connected to the dryer bank and open at the bottom, drain means for guiding moisture separated by the dryer bank to the outside of the skirt, and A lower ring connected to the lower end of the skirt, and the lower ring is formed with a groove connecting the inner side and the outer side of the lower ring at a position that becomes a node of the oval vibration of the skirt. Features.

  The invention described in claim 4 is a steam dryer for a boiling water reactor disposed so as to cover the steam separator in the reactor pressure vessel, and is disposed above the steam separator. A dryer bank that separates moisture in the steam, a cylindrical skirt connected to the dryer bank and open at the bottom, drain means for guiding moisture separated by the dryer bank to the outside of the skirt, and A drain channel is provided on the outer surface of the skirt so as to be a node of the oval vibration of the skirt, and the drain channel guides moisture guided to the outside of the skirt downward by the drain means.

  The invention according to claim 5 is a boiling water reactor steam dryer disposed so as to cover the steam separator in the reactor pressure vessel, and is disposed above the steam separator. A dryer bank that separates moisture in the steam, a cylindrical skirt connected to the dryer bank and open at the bottom, an upper ring connected to the upper end of the skirt, and a lower end of the skirt A lower ring, drain means for guiding moisture separated by the dryer bank to the outside of the skirt, and an outer surface of the skirt, which is disposed at a position that becomes a node of oval vibration of the skirt; A drain channel that guides moisture guided to the lower side, and the drain channel is disposed between the upper ring and the lower ring along the outer surface of the skirt. A ring connecting beam is located outside of the skirt at an interval from the outer surface of said skirt, having a side plate fixed to said upper ring and said ring connecting beam, characterized by.

  The invention according to claim 6 is a boiling water reactor steam dryer disposed so as to cover the steam separator in the reactor pressure vessel, and is disposed above the steam separator. A dryer bank that separates moisture in the steam, a cylindrical skirt that is connected to the dryer bank and that is open at the bottom, drain means that guides the moisture separated by the dryer bank to the outside of the skirt, and bending A side plate that is bent along a line, and both side ends of the side plate are joined to the outer surface of the skirt, and a drain channel that guides moisture guided to the outside of the skirt downward by the drain means. It is characterized by this.

  ADVANTAGE OF THE INVENTION According to this invention, the steam dryer which implement | achieves reduction of a vibration and reduction of the stress concentration in a welding part can be provided.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a steam dryer for a boiling water reactor according to the present invention will be described with reference to the drawings. Here, parts common or similar to those in the prior art and parts common to or similar to each other are denoted by common reference numerals, and redundant description is omitted.

[First Embodiment]
First, a first embodiment will be described with reference to FIGS. In this Embodiment, a steam dryer is arrange | positioned so that the outer side and upper direction of the steam-water separator 8 in a reactor pressure vessel may be covered. The steam dryer includes a dryer bank 10 disposed above the steam / water separator 8 to separate moisture in the steam, and a cylindrical skirt 1 that surrounds the steam / water separator and is open at the bottom. Have.

  Furthermore, there are provided a drain pipe (drain means) 5 that guides the water separated by the dryer bank 10 to the outside of the skirt, and a lower ring 3 that protrudes downward from the lower end of the skirt 1 and is attached to the skirt. The lower end of the lower ring 3 is below the outlet of the return water separated by the steam separator 8. A drain channel 2 similar to the prior art shown in FIGS. 10 to 14 is disposed outside the skirt 1.

  The inner opening at the lower end of the lower ring 3 is configured to gradually expand downward. That is, a notched surface that is inclined downward as shown in FIG. 1 (b) is formed from the inner surface to the outer surface of the lower end surface of the lower ring 3, or arbitrarily from the inner side to the outer side as shown in FIG. 1 (c). A curved surface having a curvature of. That is, the inner diameter of the lower ring 3 is configured to increase toward the lower end.

  When such a steam dryer is used, the flow path of the return water flow 6 from the steam / water separator 8 can be secured widely as shown in FIG. 2, so that interference with the lower ring 3 is suppressed and the flow smoothly flows. The fluctuating load on the skirt 1 is reduced.

[Second Embodiment]
A second embodiment will be described with reference to FIG. In this embodiment, as shown in FIG. 3 (c), a drain hole 12 is provided at a position that becomes a node 40 of the oval vibration of the skirt 1 as shown in FIGS. 3 (a) and 3 (b). The lower ring 3 is provided with a drainage groove 13 that connects the inside and the outside. With such a steam dryer, the return water flow can be collected at the node 40 of the oval vibration, so that the fluctuating load is also concentrated at the node 40 of the oval vibration. As a result, the fluctuating load on the skirt 1 is reduced.
In addition, although the example which provided both the drain hole 12 and the drain groove 13 is shown in FIG. 3, it cannot be overemphasized that either one has an effect.

[Third Embodiment]
A third embodiment will be described with reference to FIG. In the present embodiment, a plurality of (for example, two) ring connection beams 14 arranged in parallel between the upper ring 4 and the lower ring 3 are provided at positions where the nodes 40 of the oval vibration are formed. Then, the drain channel 2 is formed by welding a flat side plate 30 to the upper ring 4 and the pair of ring connecting beams 14. The lower end of the side plate 30 is located above the lower ring 3.
When such a steam dryer is used, the vibration of the drain channel 2 is reduced because the ring connecting beam 14 is insulated from the vibration of the skirt 1 at the position of the node 40 of the oval vibration.

[Fourth Embodiment]
A fourth embodiment will be described with reference to FIG. In the present embodiment, for example, a central portion of a metal flat plate is bent, both end portions thereof are joined to the skirt 1 by welding or the like, and the upper end of this plate is welded to the upper ring 4 to constitute the drain channel 2. It is.

  With such a configuration, the bending rigidity in the height direction of the drain channel 2 increases, so that the vibration of the drain channel 2 is reduced. Further, the width of the drain channel 2 can be made smaller than the conventional one.

[Fifth Embodiment]
A fifth embodiment will be described with reference to FIGS. In the present embodiment, as shown in FIG. 6, the lower end of the drain channel 2 of the prior art shown in FIG. Is.

  In such a boiling water reactor steam dryer, since the opening between the upper end of the lower ring 3 and the drain channel 2 is widened, the drain channel 2 and the skirt 1 can be easily welded. Further, as shown in FIG. 7, the angle between the drain channel 2 and the weld metal 15 is also increased, so that it is easy to weld in a smooth shape, and stress concentration in the welded portion is reduced.

[Sixth Embodiment]
A sixth embodiment will be described with reference to FIG. This embodiment is a modification of the fifth embodiment, in which the lower end of the drain channel 2 is cut off with a curvature obliquely inward from both side end portions of the drain channel 2.

  In such a boiling water reactor steam dryer, the opening between the upper end of the lower ring 3 and the drain channel 2 is widened, so that the drain channel 2 and the skirt 1 can be easily welded. Further, since the angle between the drain channel 2 and the weld metal 15 is also increased, it is easy to weld in a smooth shape, and stress concentration at the welded portion is reduced.

[Seventh embodiment]
The seventh embodiment will be described with reference to FIG. This embodiment incorporates the features of the fourth embodiment (FIG. 5) and the fifth embodiment (FIGS. 6 and 7). That is, a drain channel 2 having a shape in which a central portion of a metal flat plate is bent and obliquely cut off from the central portion toward both side end portions is welded to the skirt 1.

  In such a boiling water reactor steam dryer, the bending rigidity of the drain channel 2 in the height direction increases, and the vibration of the drain channel 2 is reduced. Moreover, since the opening between the upper end of the lower ring 3 and the drain channel 2 becomes wide, welding of the drain channel 2 and the skirt 1 becomes easy. Further, since the angle between the drain channel 2 and the weld metal 15 is also increased, it is easy to weld in a smooth shape, and stress concentration at the welded portion is reduced. As a modification of this embodiment, a shape in which the lower end of the drain channel 2 is cut off with curvature from both side ends as in the sixth embodiment may be used.

It is a figure which shows 1st Embodiment of the steam dryer for boiling water reactors which concerns on this invention, Comprising: (a) is the principal part perspective view which looked at the drain channel vicinity from the downward direction, (b) is (a) (C) is a partial elevational sectional view near the lower ring of (a) showing an example different from (b). The fragmentary longitudinal cross-section which shows the effect | action of the steam dryer of FIG. It is a figure which shows 2nd Embodiment of the steam dryer for boiling water reactors which concerns on this invention, Comprising: (a) is typical horizontal sectional drawing of the whole skirt for demonstrating the oval vibration of a skirt, ( (b) is a schematic horizontal sectional view of the entire skirt at a different moment from (a), and (c) is a perspective view of the main part when the skirt is viewed from below. The principal part perspective view which looked at the drain channel vicinity of 3rd Embodiment of the steam dryer for boiling water reactors which concerns on this invention from the downward direction. It is a figure which shows 4th Embodiment of the steam dryer for boiling water reactors which concerns on this invention, Comprising: (a) is the principal part perspective view which looked at the drain channel vicinity from the downward | lower direction, (b) is drain The longitudinal cross-sectional view of the channel vicinity. It is a figure which shows 5th Embodiment of the steam dryer for boiling water reactors which concerns on this invention, Comprising: (a) is the principal part perspective view which looked at the drain channel vicinity from the downward | lower direction, (b) is drain The longitudinal cross-sectional view of the channel vicinity. It is a figure which shows 6th Embodiment of the steam dryer for boiling water reactors which concerns on this invention, Comprising: (a) is the principal part which looked at the lower end part vicinity of one side edge of the drain channel from the downward direction A perspective view and (b) are the elevation sectional views near the lower end part of one side end of a drain channel. It is a figure which shows 7th Embodiment of the steam dryer for boiling water reactors which concerns on this invention, Comprising: (a) is the principal part perspective view which looked at the drain channel vicinity from the downward | lower direction, (b) is drain The longitudinal cross-sectional view of the channel vicinity. It is a figure which shows 8th Embodiment of the steam dryer for boiling water reactors which concerns on this invention, Comprising: (a) is the principal part perspective view which looked at the drain channel vicinity from the downward | lower direction, (b) is drain The longitudinal cross-sectional view of the channel vicinity. The perspective view which shows the conventional steam dryer for boiling water reactors. The fragmentary longitudinal cross-section which shows the effect | action of the steam dryer of FIG. It is a figure which shows the conventional steam dryer for boiling water reactors, Comprising: (a) is a principal part perspective view which looked at drain channel vicinity from the downward direction, (b) is a longitudinal cross-sectional view of drain channel vicinity. It is the typical horizontal sectional view of the whole skirt for demonstrating the oval vibration of the skirt of the conventional steam dryer for boiling water reactors, (a) is a figure which shows the skirt at the time of non-vibration, (b) Oval The schematic diagram which shows the skirt at the time of a vibration, (c) is a schematic diagram which shows the skirt in the different moment from (b). It is a figure which shows the lower end vicinity of one side edge part of the drain channel of the steam dryer for boiling water reactors of FIG. 12, Comprising: (a) is a fragmentary perspective view seen from the downward | lower direction, (b) is a plane sectional view (C) is a longitudinal cross-sectional view. (A) And (b) is a longitudinal cross-sectional view which shows the other example of the lower end vicinity of one side edge part of the drain channel corresponding to FIG.14 (c).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Skirt, 2 ... Drain channel, 3 ... Lower ring, 4 ... Upper ring, 5 ... Drain pipe (drain means), 6 ... Return water flow, 7 ... Steam flow, 8 ... Air-water separator, 9 ... Shroud head DESCRIPTION OF SYMBOLS 10 ... Dryer bank, 11 ... Non-vibrating skirt, 12 ... Drainage hole, 13 ... Drainage groove, 14 ... Ring connection beam, 15 ... Weld metal, 30 ... Side plate, 40 ... Node of oval vibration of skirt.

Claims (6)

A boiling water reactor steam dryer arranged to cover a steam separator in a reactor pressure vessel,
A dryer bank disposed above the steam separator to separate moisture in the steam;
A cylindrical skirt connected to the dryer bank and open at the bottom;
Drain means for guiding moisture separated by the dryer bank to the outside of the skirt;
A lower ring connected to the lower end of the skirt;
Have
A lower end portion of the lower ring is located below the outlet of the water separated by the steam separator, and is configured such that the diameter of the inner surface of the lower ring increases toward the lower end;
A steam dryer for boiling water reactors. A boiling water reactor steam dryer arranged to cover a steam separator in a reactor pressure vessel,
A dryer bank disposed above the steam separator to separate moisture in the steam;
A cylindrical skirt connected to the dryer bank and open at the bottom;
Drain means for guiding moisture separated by the dryer bank to the outside of the skirt;
Have
The skirt has a drain hole penetrating the skirt at a position that becomes a node of the oval vibration;
A steam dryer for boiling water reactors. A boiling water reactor steam dryer arranged to cover a steam separator in a reactor pressure vessel,
A dryer bank disposed above the steam separator to separate moisture in the steam;
A cylindrical skirt connected to the dryer bank and open at the bottom;
Drain means for guiding moisture separated by the dryer bank to the outside of the skirt;
A lower ring connected to the lower end of the skirt;
Have
The lower ring is formed with a groove connecting the inner side and the outer side of the lower ring at a position that becomes a node of the oval vibration of the skirt,
A steam dryer for boiling water reactors. A boiling water reactor steam dryer arranged to cover a steam separator in a reactor pressure vessel,
A dryer bank disposed above the steam separator to separate moisture in the steam;
A cylindrical skirt connected to the dryer bank and open at the bottom;
Drain means for guiding moisture separated by the dryer bank to the outside of the skirt;
A drain channel disposed on the outer surface of the skirt at a position that becomes a node of the oval vibration of the skirt, and that guides moisture guided to the outside of the skirt downward by the drain means;
A steam dryer for boiling water reactors. A boiling water reactor steam dryer arranged to cover a steam separator in a reactor pressure vessel,
A dryer bank disposed above the steam separator to separate moisture in the steam;
A cylindrical skirt connected to the dryer bank and open at the bottom;
An upper ring connected to the upper end of the skirt;
A lower ring connected to the lower end of the skirt;
Drain means for guiding moisture separated by the dryer bank to the outside of the skirt;
A drain channel disposed on the outer surface of the skirt at a position that becomes a node of the oval vibration of the skirt, and for guiding moisture guided to the outside of the skirt downward by the drain means;
A plurality of ring connecting beams disposed between the upper ring and the lower ring along the outer surface of the skirt;
A side plate disposed on the outside of the skirt at a distance from an outer surface of the skirt and fixed to the upper ring and the ring connecting beam;
A steam dryer for boiling water reactors. A boiling water reactor steam dryer arranged to cover a steam separator in a reactor pressure vessel,
A dryer bank disposed above the steam separator to separate moisture in the steam;
A cylindrical skirt connected to the dryer bank and open at the bottom;
Drain means for guiding moisture separated by the dryer bank to the outside of the skirt;
A drain plate that has a side plate bent along a folding line, both side ends of the side plate are joined to the outer surface of the skirt, and the drain channel that guides moisture guided to the outside of the skirt by the drain means; Having
A steam dryer for boiling water reactors.

Images