JPH1194978A - Reactor equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce probability of pressure vessel failure due to molten core debris by providing a projection on the surface of reactor pressure vessel bottom plate between a CRD housing and another CRD housing. SOLUTION: Control rod guide tubes 3, control rods 4 and fuel assemblies 7 extend upward from a reactor pressure vessel bottom plate 2 and CRD housings 6. In this type of reactor, the possibility of reactor pressure vessel failure due to molten core debris is predicted in the case of water injection failure after a large break LOCA. By this, in a boiling water reactor, a projection 101 is provided on the surface of reactor pressure vessel bottom plate 2 between a CRD housing 6 and another CRD housing and so formation of gap between solidified debris made of solidified molten debris and the reactor pressure vessel bottom plate 2 is promoted, water invades in this gap to promote the cooling of the pressure vessel bottom plate 2 and effect of more extending time to reactor pressure vessel failure can be expected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power plant such as a nuclear reactor, and more particularly, to a nuclear reactor suitable for preventing molten debris from falling down due to damage to a reactor pressure vessel when a core melting accident occurs. Equipment related.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 6-130169 is an example of a known technique relating to a severe accident mitigation facility in a power plant. In this known example, it is assumed that the core molten debris penetrates the reactor pressure vessel.

[0003] Fig. 7 is a structural view of a lower part of a nuclear reactor and Fig. 8 is a structural view of a nuclear reactor in the prior art.

FIG. 7 is a diagram showing a lower structure of a nuclear reactor. Control rod guide tubes 3, control rods 4, and fuel assemblies 7 extend from the reactor pressure vessel bottom plate 2 to above the CRD housing 6. In this type of reactor, assuming a severe accident,
In the case of failure of water injection after a large break LOCA, the reactor pressure vessel may be damaged by core melt debris.

Further, in FIG. 8, the nuclear reactor is provided with a cylindrical internal pump 1 instead of the shroud. A control rod guide tube 3 and a control rod 4 extend upward from the reactor pressure vessel bottom plate 2. In this type of reactor, assuming a severe accident, there is a possibility that core melt debris will directly attack the reactor pressure vessel wall 5 (portion A in FIG. 8) when the core melts.

[0006]

The above-mentioned known techniques have the following problems. In the prior art, the conventional coolant pressure vessel bottom plate 2 has a coolant flow path formed only when creep deformation due to molten debris progresses. further,
In a nuclear reactor provided with a cylinder instead of a shroud, assuming a severe accident, there is a possibility that core molten debris will directly attack the reactor pressure vessel wall 5 (portion A in FIG. 8) during core melting.

An object of the present invention is to provide a reactor facility having a structure in which the effect of creep deformation due to molten debris is promoted in the conventional reactor pressure vessel bottom plate 2. Further, in a reactor provided with a cylinder instead of a shroud, a reactor facility for preventing the possibility that core molten debris directly attacks the reactor pressure vessel wall 5 (portion A in FIG. 8) at the time of core melting in a severe accident. It is to provide.

[0008]

According to the present invention, there is provided a boiling water reactor having a CR.
A reactor facility is provided, wherein a protrusion is provided on a surface of a reactor pressure vessel bottom plate between a D housing and another CRD housing.

[0009] More preferably, in a boiling water reactor, between a CRD housing and another CRD housing.
A reactor facility is provided, wherein a pipe is provided on a surface of a reactor pressure vessel bottom plate.

[0010] More preferably, in a boiling water reactor, between a CRD housing and another CRD housing.
A reactor facility is provided in which a groove is provided on a surface of a reactor pressure vessel bottom plate.

[0011] More preferably, there is provided a nuclear reactor facility wherein a deflector is provided between the cylinder and the pressure vessel wall.

[0012] More preferably, there is provided a nuclear reactor facility wherein a heat insulating material is provided between the cylinder and the pressure vessel wall.

That is, the conventional reactor pressure vessel bottom plate 2 has not been considered with respect to a structure that promotes the effect of creep deformation due to molten debris.

According to the present invention, in a boiling water reactor, between a CRD housing and another CRD housing,
Protrusions are provided on the surface of the reactor pressure vessel bottom plate, which promotes the creation of a gap between the solidified debris in which the molten debris has solidified and the reactor pressure vessel bottom plate, and water enters this gap to cool the pressure vessel bottom plate. Since it promotes, the probability of reactor pressure vessel breakage can be reduced as compared with the conventional case.

According to the present invention, in a boiling water reactor, between a CRD housing and another CRD housing,
Since a tube is provided on the surface of the reactor pressure vessel bottom plate, there is a tube between the solidified debris in which the molten debris has solidified and the reactor pressure vessel bottom plate, and water enters this tube to promote cooling of the pressure vessel bottom plate. Therefore, the time required for damage to the reactor pressure vessel can be extended as compared with the conventional case.

According to the present invention, in a boiling water reactor, between a CRD housing and another CRD housing,
Since a groove is provided on the surface of the reactor pressure vessel bottom plate, a gap is generated between the solidified debris in which the molten debris has solidified and the reactor pressure vessel bottom plate, and water enters the gap to promote cooling of the pressure vessel bottom plate. Therefore, the time required for damage to the reactor pressure vessel can be extended as compared with the conventional case.

In a reactor provided with a cylinder instead of a shroud, assuming a severe accident, there is a possibility that core melt debris will directly attack the reactor pressure vessel wall 5 (portion A in FIG. 8) when the core melts.

In the present invention, since a deflector is provided between the cylinder and the pressure vessel wall in this region, the deflector allows molten debris to fall downward without touching the pressure vessel wall, and Pressure vessel wall 5 (A in FIG. 8)
Portion) can be prevented from being directly attacked.

In the present invention, since a heat insulating material is provided between the cylinder and the pressure vessel wall in this region, the heat insulating material allows molten debris to fall downward without exposing the pressure vessel wall to high temperatures. Direct attack on the reactor pressure vessel wall 5 (portion A in FIG. 8) can be prevented.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

A first embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows the nuclear reactor equipment of this embodiment. A first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, control rod guide tubes 3, control rods 4, and fuel assemblies 7 extend from the reactor pressure vessel bottom plate 2 to above the CRD housing 6. In this type of reactor, assuming a severe accident, it is expected that the reactor pressure vessel may be damaged by core melt debris if water injection fails after a large break LOCA. The conventional reactor pressure vessel bottom plate 2 has not been considered with respect to a structure that promotes the effect of forming a coolant passage by creep deformation due to molten debris.

According to the present invention, in the boiling water reactor, since the protrusion 101 is provided on the surface of the bottom plate of the reactor pressure vessel between the CRD housing 6 and another CRD housing, the solidified debris in which the molten debris is solidified is provided. The formation of a gap between the reactor pressure vessel bottom plate and the reactor pressure vessel bottom plate is promoted, and water enters this gap to promote cooling of the pressure vessel bottom plate, so that the time required for reactor pressure vessel breakage can be extended as compared with the conventional case.

In FIG. 2, the solidified debris 102 is held in water 103 by a projection 101 of the pressure vessel bottom plate 2, and a gap is formed between the solidified debris 102 and the pressure vessel bottom plate 2.

A second embodiment of the present invention will be described with reference to FIG. In FIG. 3, control rod guide tubes 3, control rods 4, and fuel assemblies 7 extend from the reactor pressure vessel bottom plate 2 to above the CRD housing 6. In this type of reactor, assuming a severe accident, it is expected that, if water injection fails after a large break LOCA, the reactor pressure vessel will be damaged in 4 to 5 hours due to core melt debris. Conventional reactor pressure vessel bottom plate 2
No consideration was given to the structure that promoted the effect of creep deformation due to molten debris.

According to the present invention, in the boiling water reactor, the pipe 104 is provided on the surface of the bottom plate of the reactor pressure vessel between the CRD housing 6 and another CRD housing. There is a pipe between the reactor pressure vessel bottom plates, and water enters the pipe to promote cooling of the pressure vessel bottom plate, so that the time required for reactor pressure vessel breakage can be extended more than before.

A third embodiment of the present invention will be described with reference to FIG. In FIG. 4, control rod guide tubes 3, control rods 4, and fuel assemblies 7 extend from the reactor pressure vessel bottom plate 2 to above the CRD housing 6. In this type of reactor, assuming a severe accident, it is expected that, if water injection fails after a large break LOCA, the reactor pressure vessel will be damaged in 4 to 5 hours due to core melt debris. Conventional reactor pressure vessel bottom plate 2
No consideration was given to the structure that promoted the effect of creep deformation due to molten debris.

According to the present invention, in the boiling water reactor, the groove 105 is provided on the surface of the bottom plate of the reactor pressure vessel between the CRD housing 6 and another CRD housing, so that the molten debris becomes solidified debris. A gap is formed between the reactor pressure vessel bottom plates, and water enters the gap to promote cooling of the pressure vessel bottom plate, so that there is an effect that the probability of reactor pressure vessel breakage can be reduced as compared with the conventional case.

A fourth embodiment of the present invention will be described with reference to FIG. In FIG. 5, the nuclear reactor is provided with a cylindrical internal pump 1 instead of the shroud. A control rod guide tube 3 and a control rod 4 extend upward from the reactor pressure vessel bottom plate 2. In a nuclear reactor of this type, assuming a severe accident, core melt debris is generated at the reactor pressure vessel wall 5 when the core melts.
(A portion in FIG. 5) may be directly attacked.

In the present invention, a deflector 11 is provided between the cylinder 1 and the pressure vessel wall 5 in the circumferential direction. Therefore, the deflector plate 11 allows the molten debris to fall downward without touching the pressure vessel wall, and has the effect of preventing direct attack on the reactor pressure vessel wall 5 (portion A in FIG. 5).

A fifth embodiment of the present invention will be described with reference to FIG. In FIG. 6, the nuclear reactor is provided with a cylindrical internal pump 1 instead of the shroud. A control rod guide tube 3 and a control rod 4 extend upward from the reactor pressure vessel bottom plate 2. In a nuclear reactor of this type, assuming a severe accident, core melt debris is generated at the reactor pressure vessel wall 5 when the core melts.
(A in FIG. 6) may be directly attacked.

In the present invention, a heat insulating material 12 is provided between the cylinder 1 and the pressure vessel wall 5 in the circumferential direction. Therefore, the molten debris can be dropped downward without exposing the pressure vessel wall to high temperature by the heat insulating material 12, and the reactor pressure vessel wall 5 (A in FIG. 6)
(Part) can be prevented from being directly attacked.

[0033]

According to the first embodiment of the present invention, CRD
Since the protrusion 101 is provided on the surface of the reactor pressure vessel bottom plate between the housing 6 and another CRD housing, the generation of a gap between the solidified debris in which the molten debris has solidified and the reactor pressure vessel bottom plate is promoted. Water enters,
Since the cooling of the bottom plate of the pressure vessel is promoted, there is an effect that the probability of damage to the reactor pressure vessel can be reduced as compared with the related art.

According to the second embodiment of the present invention, since the tube 104 is provided on the surface of the bottom plate of the reactor pressure vessel between the CRD housing 6 and another CRD housing, the molten debris is solidified with the solidified debris. There is a pipe between the reactor pressure vessel bottom plates, and water enters the pipe to promote cooling of the pressure vessel bottom plate, so that there is an effect that the probability of reactor pressure vessel breakage can be reduced as compared with the conventional case.

According to the third embodiment of the present invention, since the groove 105 is provided on the surface of the bottom plate of the reactor pressure vessel between the CRD housing 6 and another CRD housing, the molten debris is solidified with the solidified debris. A gap is formed between the reactor pressure vessel bottom plates, and water enters the gap to promote cooling of the pressure vessel bottom plate, so that there is an effect that the probability of reactor pressure vessel breakage can be reduced as compared with the conventional case.

According to the fourth embodiment of the present invention, since the baffle 11 is provided in the circumferential direction between the cylinder 1 and the pressure vessel wall 5, the deflector 11 lowers the molten debris without touching the pressure vessel wall. This has the effect of preventing the reactor pressure vessel wall 5 (part A in FIG. 5) from directly attacking.

According to the fifth embodiment of the present invention, since the heat insulating material 12 is provided between the cylinder 1 and the pressure vessel wall 5 in the circumferential direction,
The heat insulating material 12 allows the molten debris to fall downward without exposing the pressure vessel wall to a high temperature, and has the effect of preventing direct attack on the reactor pressure vessel wall 5 (portion A in FIG. 6).

[Brief description of the drawings]

FIG. 1 is a diagram showing a reactor lower structure according to a first embodiment of the present invention.

FIG. 2 is a view showing a reactor lower structure according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a lower structure of a reactor according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a reactor lower structure according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a reactor structure according to a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a nuclear reactor structure according to a fifth embodiment of the present invention.

FIG. 7 is a diagram showing a lower structure of a reactor according to a conventional technique.

FIG. 8 is a diagram showing a reactor structure according to the related art.

[Explanation of symbols]

1. Internal pump, 2. Reactor pressure vessel bottom plate, 3.
... control rod guide tube, 4 ... control rod, 5 ... reactor pressure vessel wall,
Reference numeral 6: CRD housing, 7: fuel assembly, 11: deflector, 12: heat insulating material, 101: protrusion, 102: solidified debris, 103: water, 104: pipe, 105: groove.

Claims (5)

[Claims] In a boiling water reactor, a projection is provided on a surface of a bottom plate of a reactor pressure vessel between a CRD housing and another CRD housing. 2. A boiling water reactor, wherein a pipe is provided on a surface of a bottom plate of a reactor pressure vessel between a CRD housing and another CRD housing. 3. A reactor facility in a boiling water reactor, wherein a groove is provided on a surface of a reactor pressure vessel bottom plate between a CRD housing and another CRD housing. 4. A nuclear reactor having a cylinder (internal pump) provided in place of a shroud, wherein a deflector is provided between the cylinder and the reactor pressure vessel wall in a circumferential direction. 5. A nuclear reactor having a cylinder (internal pump) instead of a shroud, wherein a heat insulating material is provided in a circumferential direction between the cylinder and a reactor pressure vessel wall.