JPS59150372A - Reactor container - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a nuclear reactor containment vessel called MARK-I type.

[Technical background of the invention and its problems]

There is a type of reactor containment vessel for a boiling water reactor called the MARK-■ type, and this MARK-■ type reactor containment vessel is constructed as shown in FIG. That is, numeral 1 in the figure is a dry well, which has airtightness and pressure resistance.

Inside this dry well 1 is a reactor pedestal 2.
is erected, and a reactor pressure vessel 3 is installed on this reactor pedestal 2. In addition to the reactor pressure vessel 3 described above, the dry well 1 houses a recirculation pump (not shown), other equipment, and piping.

Further, a toroidal pressure suppression chamber 4 is formed around the lower part of the dry well 1, and a large amount of pool water 5 is stored in this pressure suppression chamber 4.
Ru. Furthermore, an annular vent header 6 is provided at the upper part of the pressure suppression chamber 4 . The vent header 6 is connected to the dry well 1 through the vent pipe 7...
communicated within. Further, a plurality of down comers 8 are projected downward from the vent header 6, and the lower ends of these down comers 8 are immersed in the pool water 5.

Then, a break occurs in the piping 9 equipment (referred to as a boundary) through which the coolant flows in the dry well 1, and this dry well is damaged.

If coolant vapor leaks into the pool water 5, this vapor flows through the vent pipes 7 to the vent header 6, is ejected from the lower end of the downcomer 8 into the pool water 5, and condenses. However, the dry well 1 is configured to prevent a rise in pressure within the dry well 1.

Therefore, when a coolant loss accident occurs, the leaked coolant is contained within the dry well 1 and the pressure suppression chamber 4, and is configured to be prevented from spreading to the outside. The results of an analysis of the transient phenomena during such a loss of coolant accident are as follows. First, dry well
If a pipe rupture occurs in the dry well 1 and coolant vapor is ejected into the dry well 1, this dry well condensable gas will flow through the vent pipes 7... and the vent header 6 to the downcomer 8.
... is ejected from the lower end into the pool water 5 of the pressure suppression chamber 4. In this case, the non-condensable gas mentioned above is not condensed in the pool water 5, so as shown in FIG. 2, the downcomer 8...
A bubble 10 of this non-condensable gas is formed near the lower end. As a result, a shock wave is generated in the pool water 5, a shock load acts on the bottom of the pressure suppression chamber 4, and the water surface of the pool water 5 rises rapidly as shown by the two-dot chain line in FIG. 2, a so-called pool swell phenomenon. occurs. Then, when all the non-condensable gas in the dry well 1 moves to the gas phase portion of the pressure suppression chamber 4, coolant vapor is ejected from the lower end of the downcomer 8 and condensed.

Incidentally, the dimensions and volume of the dry well 1 are set based on the dimensions and workability of the reactor pressure vessel 3 and other equipment accommodated in the dry well 1. Also,
The maximum rupture opening area of the balun that is expected to occur in the event of a loss of coolant accident is set assuming, for example, a complete rupture of piping in the recirculation system. For example, in an 800,000 kW class boiling water reactor equipped with a conventional MARK-I type reactor containment vessel, the volume of the dry well VD is 4200 m3, and the fracture opening area A of the boundary is 0.37 m''. When illustrated, it looks like point P in Figure 3.Also, for reactor outputs other than the 800,000 kW class mentioned above, the reactor pressure vessel, other equipment, and piping should be adjusted according to the reactor output. Since the diameter of the dry well also increases, the volume VD of the dry well and the area A of the fracture opening of the boundary are also approximately proportional to the output of the reactor. The relationship is as shown by the straight line B, and this relationship is expressed as VD (m3)=KXA'(m2) K=11351(m).

Based on this relationship, we analyzed the situation during a conventional reactor containment vessel loss-of-coolant accident, and found that the rise in the water level of pool water 5 due to pool swell caused vent header 6 to rise as shown in Figure 2. It has been found that the rapidly rising water level collides with the lower surface of the vent header 6, causing impact and load to act on the vent header 6, which may adversely affect its health.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to prevent impact loads from acting on the vent header due to pool swell in the event of a loss of coolant accident, which would adversely affect the integrity of the header. The goal is to provide a nuclear reactor containment vessel that is free from damage.

[Summary of the invention]

A dry well that accommodates the reactor pressure vessel, and a l/l tank surrounding this dry well that stores pool water inside.
- A lath-shaped pressure suppression chamber, an annular vent header provided at the top of the pressure suppression chamber, a vent pipe that communicates the vent header with the inside of the drywell, and a vent pipe that projects downward from the penthead header. and a downcomer whose lower end is immersed in the pool water, the volume of the dry well is VD [m, 3:), and the expected fracture opening area of the boundary in the event of a coolant loss accident is A [m2].
], then VD≧30340 (m: IXA). Therefore, this - is the fracture opening area A, that is, the dry well area for the coolant vapor flow rate that leaks in the event of a coolant loss accident. This reduces the initial pressure rise in the drywell in the event of a loss of coolant accident.This reduces the pressure of the non-condensable gas ejected into the pool water from the bottom of the downcomer. , pool swell is suppressed.

If the above formula is satisfied, the rise in the pool water level due to the pool swell will be equal to or lower than the lower surface position of the vent header in a standard pressure suppression chamber, and this pool swell will prevent impact loads from acting on the vent header. and ensure that any adverse effects on its integrity are prevented.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to FIGS. 4 to 9. In the figure, 101 is a dry well, which has airtightness and pressure resistance. A reactor pedestal 102 is erected within this dry well 101, and a reactor pressure vessel 1 is placed on this reactor pedestal 102.
03 is installed. Also, this dry well 10
In addition to the above-mentioned reactor pressure vessel 103, there is a recirculation pump (not shown) and other equipment inside.

Contains piping, etc. Also, this dry well 10
A pressure suppression chamber 104 having a toroidal shape is formed around the lower part of the pressure suppression chamber 104.
A large amount of pool water 105 is stored inside. Also,
An annular vent header 106 is provided at the upper part of the pressure suppression chamber 104 . The vent header 106 is communicated with the inside of the dry well 10 via vent pipes 107. Further, from this vent header 106, a plurality of downcomers 108 and
... are protruding from these downcomers 108...
The lower end of is immersed in the above-mentioned Nord water 105.

If a rupture occurs in two piping devices (referred to as boundaries) through which the coolant flows in the dry well 101 and coolant vapor leaks into the dry well 101, the vapor leaks into the dry well 101. is vent pipe 107...
through the vent header 106 and the downcomer 108
... is ejected from the lower end into the pool water 105 and condenses, thereby preventing a rise in pressure within the dry well 101.

And this reactor has an output of 110! Although it is a 10,000 kW class, the diameter of boundary piping such as recirculation system piping has been reduced, and the maximum fracture opening area A expected in the event of a loss of coolant accident has been reduced to 0.29-712. Also,
The volume DCtn3] of the dry well 101 is a volume that satisfies the fracture opening area A (second) of the boundary, for example, VD = 8800 Cm3:l
is set to .

Further, the pressure suppression chamber 104 has standard dimensions,
The radius R of the cross section is 4450 wn, and the vent header 1
The diameter r of 06 is 1480 trrm 1 pool water 105
The height H from the water surface to the bottom surface of the vent header 106 is 1
It is 310w++. In addition, FIG. 5 shows the relationship between this fracture opening area A and the volume of the dry well 101, and the straight line C
The shaded area of the straight line expressed by the above equation (1) is the area where the above equation (1) is satisfied, and the point P' indicates the case of this first embodiment. Note that a straight line B shows the relationship between the conventional fracture opening area A and the dry well VD.

The first embodiment of the present invention configured as described above has a rupture opening area A of the boundary, that is, a volume V of the dry well 101 with respect to a vapor flow rate of the coolant leaking at the time of a coolant loss accident.
Since D is large, as shown by the solid line in FIG. 7, the increase in the pressure inside the dry well 101 at the initial stage of a coolant loss accident is small. Note that the broken line in FIG. 7 shows the conventional case. Therefore, in the early stage of a coolant loss accident, the pressure of non-condensable gases such as air and nitrogen gas spouted from the lower end of the downcomer 10B into the sol water 105 becomes low, as shown by the solid line in FIG. The vertical impact load acting on the wall of the suppression chamber 104 is significantly alleviated. Note that the broken line in FIG. 8 shows the conventional case. Also, downcoma 108・
The pool swell phenomenon is also alleviated by the pressure drop of the non-condensable gas ejected from the pool water 105, and the height of the rise in the water level of the pool water 105 is reduced. In the case of this first embodiment, that is, in the case of VD = 30340 (m) Therefore, as shown in FIG. 9, the impact pressure acting on the vent header 106 becomes extremely low. Note that the broken line in FIG. 9 is for the conventional case. Therefore, the health of the vent header 106 is prevented from being adversely affected.

Note that FIGS. 10 and 11 show the configuration of a pressure suppression chamber 104 in a second embodiment of the present invention. In this second embodiment, the pressure suppression chamber 104 is made larger than the standard one, the radius R of the cross section of the pressure suppression chamber 104 is 5000 m, the diameter r of the vent header 106 is 1300 nm, and the center of the vent header 106 is Move the position to a position 0.45H from the center of the pressure suppression chamber 104 and position it above the standard one, and remove the vent header 1 from the surface of the sol water 105.
The height H to the bottom surface of 06 is 2300 thighs. Note that the volume of the pressure suppression chamber 104 in this second embodiment is 9
It is 100m3.

Further, this second embodiment has the same structure as the first embodiment except for the dimensions of the pressure suppression chamber 104. In this second embodiment, the vent header 10 is
Since the height H to the bottom surface of No. 6 has sufficient margin,
As shown by the two-dot chain line in the figure, the position where the water level rises due to the pool swell is far below the lower surface of the vent header 106, and impact is reliably prevented from acting on the vent header 106. [Effects of the Invention] The above-mentioned The present invention comprises a dry well housing a reactor pressure vessel, a toroidal pressure suppression chamber surrounding the drywell and storing pool water inside, and an annular pressure suppression chamber provided in the upper part of the pressure suppression chamber. The dry well comprises a vent header, a vent pipe communicating the vent header with the inside of the dry well, and a downcomer that projects downward from the vent header and has a lower end immersed in the pool water. The volume of the well is Vn (m3)
, the expected boundary rupture opening area during a loss of coolant accident is AC? 722:], then VD≧30340 (m: IXA).Therefore, this is the fracture opening area A, i.e. Since the volume of the well is large, the initial pressure rise in the dry well in the event of a coolant failure is reduced.This reduces the pressure of non-condensable gas ejected from the bottom end of the downcomer into the pool water. becomes low and pool swell is suppressed.

If the above formula is satisfied, the rise in the pool water level due to the pool swell will be equal to or lower than the lower surface position of the vent header in a standard pressure suppression chamber, and this pool swell will cause an impact load to act on the vent header. The effects of this are significant, such as preventing the occurrence of problems and reliably preventing adverse effects on the soundness of the system.

[Brief explanation of the drawing]

Figures 1 to 3 show conventional examples, where Figure 1 is a longitudinal cross-sectional view of the entire structure, Figure 2 is a cross-sectional view of the pressure suppression chamber, and Figure 3 is the relationship between the fracture opening area of the boundary and the dry well volume. FIG. 4 to 9 show a first embodiment of the present invention, FIG. 4 is a longitudinal cross-sectional view of the whole, and FIG. 5 is a diagram showing the relationship between the area of the fracture opening of the undary and the dry well volume. , Figure 6 is a cross-sectional view of the pressure suppression chamber, Figure 7 is a line diagram showing changes in dry well pressure, Figure 8 is a line diagram showing vertical loads acting on the pressure suppression chamber, and Figure 9 is a diagram showing the vertical load acting on the pressure suppression chamber. FIG. 3 is a diagram showing impact pressure acting on the header. FIG. 10 and the first figure are cross-sectional views of the pressure suppression chamber of the second embodiment. 101...Dry well, 103...Reactor pressure vessel, 104...Pressure suppression chamber, 105...Pool water,
106...Vent header, 107...Vent pipe, 1
08...Downcomer. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 4 105 Figure 5 Designed frontage area (m2) Figure 10 Figure 11 423-

Claims (1)

[Claims] A dry well that accommodates a reactor pressure car vessel, a toroidal pressure suppression chamber that is provided surrounding the dry well and stores sol water inside, and a toroidal pressure suppression chamber that is provided in the upper part of the pressure suppression chamber. an annular vent header, a vent pipe that communicates the vent header with the inside of the dry well, and a downcomer that projects downward from the vent header and has a lower end immersed in the pool water. , the volume of the dry well is VD [m3], and the expected rupture opening area in the event of a loss of coolant accident is A C? F
12], a reactor containment vessel characterized in that VD≧30340(m:)XA.