JPS5821197A - Emergency core cooling system of atomic power plant - 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 The present invention relates to an emergency core cooling system for dealing with abnormal situations such as a loss of coolant accident in a nuclear power plant.

In general, an emergency core cooling system used in a boiling water nuclear power plant has the configuration shown in FIG. Water injection pipes 3, 4, 5, and 6°7 are connected to each other. Each core cooling water injection pipe 3, 4, 5, 6.7 is independent from each other.

Each water injection pump 8a, 8b, 8c, 8d, 8e
Cooling water from the reactor pressure vessel 2 is injected into the reactor pressure vessel 2.

Each core cooling water injection pipe is provided with normally closed isolation valves 9a, 9b, 9c, 9d, 9e and check valves on the outside of the reactor enclosure l, Oa, lOb, lOa, 10d',
10e are arranged in series, and depending on the mechanism for injecting water into the reactor pressure vessel 2, high pressure core spray system piping 3. Low pressure core line system piping 4. Low pressure water injection system piping 5,
It is divided into 6.7.

However, if a coolant loss accident occurs in which the water level in the reactor pressure vessel 2 drops for some reason.

The water injection pumps 8a to 8e of the emergency core cooling system are started all at once, the isolation valves 9a to 9e are opened, and the reactor pressure vessel 2
Cooling water is injected into the reactor to prevent accidents within the nuclear power plant.

At this time, the normally closed isolation valves 9a to 9@ open simultaneously.

Each water injection tie pump 8a to 8e is activated at the same time.

Each pump and box has undergone sufficient quality control and is highly reliable.

However, in the unlikely event that the water injection pump 8a and isolation valve 9b fail and do not operate, even if the other water injection pumps 8b to 8 and isolation valves 9a and 9a to 9e operate normally, the two systems There is a risk that the core cooling water injection piping 3.4 will not lose its cooling water injection function and the inside of the reactor pressure vessel 2 will not be able to be sufficiently cooled. By connecting the core cooling water injection pipes with connecting pipes, the functions of each core cooling water injection pipe are mutually compensated, and the emergency core cooling system of a nuclear power plant is designed to effectively cope with abnormal situations such as loss of coolant accidents. The purpose is to provide equipment.

The actual MN of the emergency core cooling system for a nuclear power plant according to the present invention will be explained below.

In FIG. 2, reference numeral 20 indicates a reactor containment tea utensil installed in a boiling water nuclear power plant, and a reactor pressure vessel 21 is housed inside this reactor containment tea utensil. A reactor core portion 22 is configured within the reactor pressure vessel 21 .

A plurality of independent core cooling water injection pipes 23 , 24 , 25 , 26 , and 27 are connected to the reactor pressure vessel 21 , respectively. Each of the core cooling water injection pipes 23 to 27 protrudes to the outside through the partition wall of the reactor containment vessel, and is connected to a water injection pump 30a through normally closed isolation valves 28a to 29a and check valves 29a to 29a. 30 e respectively.

Each core cooling water injection piping ~n is divided into high pressure core spray system piping B, low pressure core spray system piping, and low pressure core water injection system piping δ~n according to the function of use.

Each of the core water injection system pipes 27 to 27 is connected to a communication pipe between the normally closed isolation valves 28a to 28 and the check valves 29a to 29m. The connecting pipe 35 constitutes a closed loop. Connecting piping A is connected to each joint of each core cooling water injection pipe O~n (
at least 11 normally-closed isolation valves 36 between the
A to 36. are provided.

In addition, in FIG. 2, numerals 37 and 38 indicate the cooling water circulation system, and 39a to 39o indicate the water injection pump 30a in case of an emergency.
This is an emergency diesel generator that drives the ~30e.

Each of the water injection pumps 30a to 30e has approximately the same pump capacity and can be used interchangeably.

Next, the operation of this invention will be explained.

When a loss of coolant accident occurs in a nuclear power plant, the cooling water in the reactor pressure vessel 21 is lost and the water level drops abnormally.

This drop in water level is detected by a detector (not shown), and each water injection pump 30 & ~ 30e is activated, and each isolation valve 28a is activated.
~Open 28a. As a result, each water injection pump 30a to 3
Cooling water from 0s is supplied to the reactor core 22 in the reactor pressure vessel 21 through core cooling water injection pipes n to n to cool the reactor core ρ.

At this time, if the water injection pump 30a does not start and the isolation valve 28b does not open, each of the other water injection pumps 30a
b-3Qe and isolation valves 28a, 28e
~28 Even if e operates normally, the reactor pressure vessel 21
The cooling water injected into the interior is only that discharged from the water injection pumps 30c to 30e, and the state of this water injection is displayed on the display panel in the central operation room.

Therefore, the operator should check the display on the above display panel and
By opening isolation box 36b, cooling water discharged from water injection pump 30b can be sent into reactor pressure vessel 21 via check valve 29b, isolation valves 36b and 28a. Therefore, the connecting pipe 35 and each isolation valve 36a~
36e, the cooling water from the water injection pump, which was wasted in the past, can be effectively utilized.

Further, assuming that the water injection pump 30c and isolation valve 28e fail, in this case, isolation 9P36d.

By opening 36e, the water injection pump 30d
.

The cooling water 30e can be injected into the reactor pressure vessel 21 through the isolation valves 28c, 28d.

Therefore, even if a failed device exists in a piping system other than the adjacent piping system, cooling water can be effectively injected.

In addition, in the detailed description of this invention, the connecting pipe 35
Although the case where the operator operates each of the isolation valves 36a to 36e has been described, it is of course possible to operate the isolation valves 36a to 36e automatically.

Further, in the following example, an example in which the present invention is applied to a boiling water type nuclear power plant has been described, but the present invention is not necessarily limited to a boiling water type nuclear power plant, and may be applied to other types of nuclear power plants. .

Furthermore, two or more connecting pipes may be connected in parallel.

As described above, in the emergency core cooling H1t of a nuclear power plant according to the present invention, since a plurality of independent core cooling water injection pipes are connected by connecting pipes, each core cooling water injection Even if piping equipment breaks down at multiple locations, each function of each core cooling water injection piping can be mutually compensated and adverse effects can be kept to a minimum, making it an effective countermeasure against coolant loss accidents. This has the effect of significantly improving the safety of nuclear power plants.

[Brief explanation of drawings]

FIG. 1 shows a conventional emergency core cooling system for a boiling water nuclear power plant. FIG. 2 shows an embodiment of an emergency core cooling system for a nuclear power plant according to the present invention. 20...Reactor containment vessel, 2j...Reactor pressure vessel. 22... Core part, 23-27... Water injection piping for core cooling, 28a-28e-isolation valve, 29a-29e-inverted I
E-sho, 30a ~ 30e... Water pump, 35...
・Connection piping, 36a~aθ...isolation valve・Applicant's agent Kiyoshi Inomata

Claims (1)

[Claims] 1. Connecting a plurality of independent core cooling water injection pipes each having a check valve and a normally closed isolation valve to a reactor pressure vessel,
In the emergency core cooling system of a nuclear power plant, which injects cooling water into the reactor pressure vessel through the core cooling water injection piping in the event of an emergency such as a loss of coolant accident, each core cooling water injection piping is connected. They are characterized by being connected to each other by piping. Emergency core cooling system at a nuclear power plant. 2. Emergency core cooling of a nuclear power plant according to claim 1, wherein the connecting pipe is connected between the check valve of each core cooling pipe and the normally closed isolation valve to form a closed loop. Device. 3. The emergency core cooling system for a nuclear power plant according to claim 1, wherein the communication piping has at least one normally closed isolation valve between the joints of each core cooling piping.