JPH04136792A - Reactor containment vessel - Google Patents

Abstract

PURPOSE:To prevent the production of fission products by making possible direct supply of spray water for a reactor pressure vessel with the use of a containment vessel sprayer and forming a water passage for causing spray water to fall to a pedestal cavity from the part between a reactor pressure vessel and a biological shielding wall. CONSTITUTION:A spray header 11 composed to make possible direct supply of spray water for a reactor pressure vessel 2 in a dry well 3 is provided in containment vessel 8a of a reactor containment vessel 1a. A water passage 12 communicating a pedestal cavity 5 formed at the lower part of the reactor containment vessel 2 and the part between the reactor containment vessel 2 and a biological shield 4 is formed and the spray water sprayed to the reactor containment vessel 2 is caused to fall in the pedestal cavity 5 with the use of the water passage 12. Thereby, even if a core meltdown accident should occur, the reaction between a meltdown core and concrete is prevented and the production of fission products is prevented.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a nuclear reactor containment vessel.

(Prior Art) Generally, in a nuclear facility such as a nuclear power plant, a reactor pressure vessel housing a reactor core is housed within a reactor containment vessel.

FIG. 2 shows an example of such a conventional reactor containment vessel. The reactor containment vessel 1 is formed into a container shape of, for example, concrete, and the reactor pressure vessel 2 that accommodates the reactor core is , is stored in a dry well 3, and a biological shielding wall 4 is formed around it.

In addition, a pedestal cavity 5 is formed in the lower part of the reactor pressure vessel 2.
A wet well 7 for storing suppression boule water 6 is formed around the .

In such a reactor containment vessel 1, a containment vessel spray 8 is usually installed to lower the pressure and temperature in the atmosphere of the dry well 3 and to remove floating nuclear fission products. This containment vessel spray 8 is normally configured to spray suppression bottle water 5 using a pump 9, but in an emergency, a pipe 10 connected to an external spray water source is provided so that a fire extinguishing water source, seawater, etc. can also be used. There is.

(Problem to be solved by the invention) According to recent probabilistic safety evaluations of nuclear reactors, a large portion of the risk is an accident in which a transient event occurs in a nuclear reactor and multiple failures occur in the emergency core cooling system. occupies .

In such an accident, the reactor scrams early in the event, but the reactor water level continues to drop due to decay heat.

If all of the emergency core cooling systems fail, the water level in the reactor continues to drop, exposing the core and leading to meltdown. Also, the generated steam is led to a suppression pool through a safety relief valve, where it condenses. When the core begins to melt, fission products (Fission P) are released from the fuel pellets.
product ) is released. However, fission products other than noble gases are easily aerosolized, so when they are released from the safety relief valve into the suppression boule, most of them are trapped in the pool due to the scrubbing effect of the pool, and very little is released into the environment.

If the accident progresses, the reactor core could collapse and fall into the lower plenum of the reactor pressure vessel, then break the bottom of the reactor pressure vessel and fall into the pedestal cavity, where it could react with the concrete. When the molten core falls onto the pedestal cavity floor, the atmosphere and structures within the drywell are heated primarily by radiation. Additionally, the reaction between the molten core and the concrete generates hot, non-condensable gases that further warm and heat the containment vessel and potentially damage the drywell. Is there a possibility that fission products will be released during the reaction between the molten core and concrete?If the drywell is damaged,
Since these fission products are not scrubbed by the suppression boule, they are likely to be released into the environment, posing a major problem in terms of public radiation exposure.

In addition, if the reactor pressure vessel is not cooled, the fission products attached to the structures inside the reactor pressure vessel will be heated by the decay heat of the fission products, reevaporate, and pass through the dry well to the environment. may be released.

The present invention has been made in response to such conventional circumstances, and even if a core meltdown accident occurs, it is possible to prevent the reaction between the molten core and concrete and prevent the generation of nuclear fission products. The present invention also aims to provide a reactor containment vessel that can prevent re-evaporation of fission products from the reactor pressure vessel.

[Structure of the Invention] (Means for Solving the Problems) That is, the present invention provides a biological shielding wall formed around a nuclear reactor pressure vessel, and a bed cell cavity formed below the reactor pressure vessel. and a containment vessel spray that supplies spray water, the containment vessel spray is configured to be able to supply spray water directly to the reactor pressure vessel, and the containment vessel spray is configured to be capable of supplying spray water directly to the reactor pressure vessel. The present invention is characterized in that a water flow path is formed for causing spray water to fall into the pedestal cavity from between the living body shielding wall and the pedestal cavity.

(Function) In the conventional reactor containment vessel, even if the containment vessel spray is restored during an accident, the spray water from the containment vessel spray cannot be directly supplied to the reactor pressure vessel. The spray had little effect on cooling the reactor pressure vessel. In addition, since the dry well and wet well are directly connected by a vent pipe, the spray water sprayed into the dry well mostly falls into the wet well, and the amount of spray water flowing into the pedestal cavity is reduced. The molten core that fell into the pedestal cavity could hardly be cooled.

In the reactor containment vessel of the present invention, the containment vessel spray is configured to be able to supply spray water directly to the reactor pressure vessel, and the spray water is dropped into the pedestal cavity from between the reactor pressure vessel and the biological shielding wall. By forming a water flow path, the molten reactor core that has fallen into the reactor pressure vessel and pedestal cavity can be cooled by containment vessel spray. Therefore, even if a core meltdown accident occurs, it is possible to prevent the reaction between the molten core and concrete and the generation of fission products, and also to prevent the re-evaporation of fission products from the reactor pressure vessel. It can be prevented.

(Example) Hereinafter, details of the present invention will be described with reference to the drawings.

FIG. 1 shows the structure of a reactor containment vessel according to an embodiment of the present invention. The same parts as those of the conventional reactor containment vessel shown in FIG. Omitted.

Containment vessel spray 8 of the reactor containment vessel 1a of this example
A spray header 11 configured to be able to directly supply spray water to the reactor pressure vessel 2 in the dry well 3 is provided at a. In addition, a water flow path 12 is formed that communicates between the reactor pressure vessel 2 and the biological shielding wall 4 and the pedestal cavity 5 formed at the bottom of the reactor pressure vessel 2. The sprayed water is transferred to the pedestal cavity 5 by this water flow path 12.
It is designed to be dropped into the

That is, in the reactor containment vessel 1a of this embodiment, when the containment vessel spray 8a is restored during the course of an accident, spray water is directly supplied to the reactor pressure vessel 2 by the rudder 11 to the spray of this containment vessel spray 8a. Can be cooled. Moreover, since this spray water falls into the pedestal cavity 5 through the water flow path 12, even if the molten core falls into the pedestal cavity 5, the molten core can be cooled. Therefore, it is possible to prevent the reaction between the molten core and the concrete, thereby preventing the generation of nuclear fission products, and it is also possible to prevent the re-evaporation of the fission products from the reactor pressure vessel 2.

[Effects of the Invention] As explained above, according to the reactor containment vessel of the present invention, even if a core meltdown accident occurs, the reaction between the molten core and concrete can be prevented and the generation of nuclear fission products can be prevented. It is possible to prevent the re-evaporation of fission products from the reactor pressure vessel.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing the structure of a reactor containment vessel according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing the structure of a conventional reactor containment vessel. 1a...... Reactor containment vessel 2...
・・・・・・Reactor pressure vessel 4・・・・・・・・・・・・
Biological shielding wall 5...Pedestal cavity 8
a... Containment vessel spray 11...
...Spray header 12 ...Water flow path Applicant: Toshiba Corporation

Claims (1)

[Claims] (1) A reactor containment vessel that includes a biological shielding wall formed around the reactor pressure vessel, a pedestal cavity formed below the reactor pressure vessel, and a containment vessel spray that supplies spray water. wherein the containment vessel spray is configured to be able to supply spray water directly to the reactor pressure vessel, and a water flow that drops the spray water from between the reactor pressure vessel and the biological shielding wall to the pedestal cavity. A nuclear reactor containment vessel characterized by forming a channel.