JPH0440397A - Nuclear reactor pressure vessel cooling device - Google Patents

Abstract

PURPOSE:To prevent a nuclear reactor pressure vessel from breaking by circulating cooling water in the space between the nuclear reactor pressure vessel and steel-made container from a pressure suppression system through a remaining heat removal system in emergency. CONSTITUTION:When abnormality occurs, the device is put in operation automatically or manually to inject the cooling water in a pressure suppression chamber 6 or condensate storage tank 13 into the space 3 between the nuclear reactor pressure vessel 2 and steel-made container 4 through injection piping 11. Consequently, a damaged reactor core deposited on the lower plenum of the pressure vessel 2 is cooled. The cooling water is sent back to the suppression chamber 6 through discharge piping 12 scooped up again by a remaining heat removal system pump 9, and cooled gradually by a remaining heat removal system heat exchanger 10 and injected into the space 2 again. Further, even when the pressure vessel 2 breaks directly, the cooling water in the pressure vessel 2 can be recirculated to the reactor core 1 only by flowing out of the breakage place into the space 2 to terminate an accident.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a nuclear reactor pressure vessel cooling system that can prevent damage to the reactor pressure vessel even when the reactor core is damaged.

(Prior art) In general, a nuclear coolant binder in a nuclear power plant consists of a reactor pressure vessel that houses the reactor core, and during normal operation, injects cooling water into the reactor core and sends boiling water heated in the reactor core to a steam turbine. It consists of a reactor containment vessel that houses reactor cooling equipment. Additionally, the reactor pressure vessel is equipped with an emergency core cooling facility for cooling the reactor core in an emergency, and a residual heat removal system for removing decay heat generated in the reactor.

According to recent probabilistic safety assessments, if an accident occurs in a nuclear reactor and multiple failures occur in the normal and emergency core cooling systems, the reactor core will be damaged, and this damaged core will be transferred to the reactor pressure vessel. It is predicted that there is a risk of destroying the nuclear reactor, and even part of the reactor containment vessel, releasing some of the radioactive materials accumulated in the reactor core into the external environment.

(Problem to be solved by the invention) In such a case, it is possible to cool the core by injecting coolant into the interior of the conventional reactor pressure vessel, but it is possible to cool the core by injecting coolant into the interior of the conventional reactor pressure vessel, but it is possible to cool the core by injecting coolant into the interior of the conventional reactor pressure vessel. Therefore, if the reactor core is damaged and it is deposited in the lower plenum of the reactor pressure vessel, only gradual cooling can be expected due to natural circulation from the upper part of the deposit, thus preventing damage to the lower part of the reactor pressure vessel. There is a high possibility that it cannot be prevented.

In the unlikely event that a reactor pressure vessel is damaged, the damaged materials will scatter inside the containment vessel, causing the containment vessel to rupture due to the pressure and temperature rise inside the containment vessel, and there is a risk that radioactive materials will be released into the external environment.

In addition, in the event that the reactor pressure vessel is directly damaged for some reason, although the frequency of occurrence is low, the emergency core cooling equipment will operate and supply cooling water into the reactor pressure vessel.
Most of the supplied cooling water flows out from the damaged part of the reactor pressure vessel, so there is little cooling of the reactor core. There is a risk of release into the environment.

The present invention has been made to reduce such risks, and even in the event of an accident at a nuclear power plant, the damaged core can be removed from the reactor without releasing radioactive materials into the reactor building or the outside environment. The purpose is to provide a reactor pressure vessel cooling system that can be confined within a pressure vessel and that can reliably prevent major accidents and leakage of radioactivity to the outside even if the reactor pressure vessel is directly damaged. be.

[Structure of the Invention] (Means for Solving the Problems) A reactor pressure vessel cooling device of the present invention includes a reactor pressure vessel,
In a nuclear reactor having an emergency core cooling facility and a residual heat removal system, the reactor pressure vessel is surrounded by a steel vessel with an appropriate space, and in an emergency, cooling water in the pressure suppression chamber is removed from the residual heat removal system. The cooling water is pumped up by a heat removal system pump, cooled by a residual heat removal system heat exchanger, and then injected into the space through an injection pipe, and the cooling water flowing out from this space is introduced into the pressure suppression chamber through a discharge pipe. It is characterized by the fact that

(Function) In the reactor pressure vessel cooling system of the present invention having such a configuration, in an emergency, cooling water is injected between the reactor pressure vessel and the surrounding steel vessel from the injection pipe of the residual heat removal system. Ru. After this cooling water flows into the suppression chamber, it is circulated through the residual heat removal system heat exchanger by the residual heat removal system pump, so that in the unlikely event that the core is damaged, damaged materials will accumulate in the lower plenum of the reactor pressure vessel. Even in such a case, the deposits are cooled by cooling from the outside of the reactor pressure vessel, and damage to the reactor pressure vessel can be prevented.

(Example) Next, the present invention will be described in detail with reference to the drawings.

The figure shows a schematic configuration of a nuclear power plant equipped with a reactor pressure vessel cooling system according to the present invention, in which a reactor pressure vessel 2 housing a reactor core 1 is arranged with a space 3 of appropriate size outside the reactor pressure vessel 2. It is surrounded by an airtight steel container 4. These structures are stored in the upper part of the containment vessel 5,
A large number of vent pipes 7 connect the upper part of the containment vessel to a pressure suppression chamber 6 disposed below the containment vessel.

The cooling water 8 in the pressure suppression chamber 6 is pumped up by the residual heat removal system pump 9, cooled by the residual heat removal system heat exchanger 10, and then transferred between the reactor pressure vessel 2 and the steel vessel 4 by the injection pipe 11. is supplied to the space 3 of. Further, the cooling water from the space 3 returns to the pressure suppression chamber 6 through the discharge pipe 12.

13 indicates a condensate storage tank communicating with the cooling water 8 in the pressure suppression chamber 6.

It should be noted that, as a matter of course, various piping systems and equipment for regular or emergency use are installed in the reactor pressure vessel 2 in addition to the main steam pipe and the reactor water supply line. Since they are unrelated, their descriptions will be omitted.

In the reactor pressure vessel cooling system configured as described above, when an abnormality occurs in the nuclear power plant, the emergency core cooling equipment is activated to cool the reactor core 1, but the emergency core cooling equipment is activated due to some circumstances. If you don't,
The reactor core 1 melts and the reactor pressure vessel 2 is damaged as a damaged core 1a.
deposited on the lower Blenheim.

In such a case, the reactor pressure vessel cooling system of the present invention is activated automatically or manually, and the pressure suppression chamber 6 is activated.
Or, the cooling water in the condensate storage tank 13 is transferred to the injection pipe 11.
Water is injected into the space 3 between the reactor pressure vessel 2 and the steel vessel 4 through the reactor pressure vessel 2 and the steel vessel 4. As a result, the damaged core 1a deposited on the lower blemish of the reactor pressure vessel 2 is cooled.

The cooling water that has cooled the damaged core 1a is returned to the pressure suppression chamber 6 through the discharge pipe 12, pumped up again by the residual heat removal system pump 9, heat removed by the residual heat removal system heat exchanger 10, and then returned to the reactor. Water is injected into the space 3 between the pressure vessel 2 and the steel vessel 4.

As a result, the damaged core 1a deposited on the lower blemish of the reactor pressure vessel 2 is cooled, and damage to the reactor pressure vessel 2 is prevented.

Furthermore, even in the event that the reactor pressure vessel 2 is directly damaged, the coolant inside the reactor pressure vessel 2
It only flows out from the damaged part into the space 3 between the reactor pressure vessel 2 and the steel vessel 4, and the reactor core 1 can be submerged again by the device of the present invention, thereby making it possible to end the accident.

[Effects of the Invention] As described above, according to the reactor pressure vessel cooling system according to the present invention, even if a core meltdown accident occurs due to some circumstances, damaged core deposited on the lower brenum of the reactor pressure vessel can be removed. is cooled down, allowing the accident to end safely without scattering radioactive materials to the outside.

Furthermore, even if an accident occurs in which the reactor pressure vessel is directly damaged, the accident can be safely brought to a close without damaging the reactor core.

[Brief explanation of drawings]

The figure is a system diagram showing an embodiment of the reactor pressure vessel cooling system of the present invention. 1......Core 2...Reactor pressure vessel 3...Space 4...Steel vessel 5 ...... Containment vessel 6 ...... Pressure suppression chamber 7 ...... Vent pipe 8 ... Cooling water 9 ...・・・・・・Residual heat removal system pump 0・・・・・・
... Residual heat removal system heat exchanger 1 ... Injection piping 2 ... Discharge piping 3 ... Condensate storage tank

Claims (1)

[Claims] In a nuclear reactor that has a reactor pressure vessel, emergency core cooling equipment, and residual heat removal system, the reactor pressure vessel is surrounded by a steel vessel with an appropriate space, and in an emergency, the pressure suppression chamber is Cooling water is pumped up by the pump of the residual heat removal system, cooled by the heat exchanger of the residual heat removal system, and then injected into the space through the injection pipe, and the cooling water flowing out from this space is sent to the pressure suppression chamber through the discharge pipe. A nuclear reactor pressure vessel cooling system configured to be installed in a nuclear reactor pressure vessel.