JP2644949B2 - Reactor water supply method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for replenishing reactor water.

[0002]

2. Description of the Related Art Conventionally, a system having a function of replenishing reactor water when a reactor water level drops due to a reactor transient, that is, a replenishing water source of a reactor isolation cooling system (RCIC), includes a condensate storage tank, a suppression pool, and the like. Water sources have been diversified by using these together.

[0003] In a cooling system at the time of reactor isolation of a boiling water reactor (BWR) plant, when the water level in the condensate storage tank drops, the makeup water source is switched to a suppression pool, and this switching operation is manually performed. Is being done.

On the other hand, an improved boiling water reactor (ABWR)
In the plant, the reactor isolation cooling system has been incorporated into an emergency core cooling system (ECCS) network to enhance the high pressure emergency core cooling system. Accordingly, when the reactor water is lost due to a pipe break, when the reactor water flows into the suppression pool and the water level in the suppression pool rises, the pressure in the containment vessel is increasing.

In order to automatically suppress the pressure increase in the containment vessel, the original design of the improved boiling water reactor is similar to that of the high pressure system emergency core cooling system in the conventional boiling water reactor plant. For water source switching, the following automatic switching logic was planned. An explanatory diagram of this automatic switching logic is shown in FIG.

That is, FIG. 5 shows that when a condensate storage tank is used as a replenishment water source for reactor water, when the condensate storage tank has a low water level or the suppression pool has a high water level, the replenishment water source for the reactor water is changed. This indicates that the condensate storage tank is switched to the suppression pool.

[0007] The above automatic switching logic is based on the Kashiwazaki-Kariwa Nuclear Power Station, Reactor Installation Change Permission Application (3,
Unit 4 Reactor) [April 1985 (partially amended in April 1986) (partially amended in February 1987) Appendix 8, Section 5.2.4.3 of Tokyo Electric Power Company ]
This is a known technique.

The reactor isolation cooling system is an emergency core cooling system.
Installed in a conventional boiling water reactor plant
Also has a function of replenishing reactor water during a reactor transient event
ing. In other words, in addition to reactor water loss,
Even at times, the suppression pool has reached a high water level
If replenished, as shown in the automatic switching logic of FIG.
The water source is switched, and supplements that are
The water in the lesson pool was being replenished into the furnace.

Japanese Patent Publication No. 64-2233 discloses that
The following related technologies are disclosed. That is, usually
Cooling system at the time of reactor isolation using condensate storage tank as water supply
And high pressure core spray system and low water level of condensate storage tank
Signal or high signal from the suppression pool.
Means for switching water source to suppression pool
Water in a suppression pool at a nuclear reactor plant
If a height signal is given, further loss of coolant detection
The switching means operates only when there is a signal.
Are disclosed.

Conventionally, even during a reactor transient event,
If the pool is at a high water level,
And unfavorable water quality as a makeup water source
The pool was being used.

However, the water stored in the suppression pool contains a large amount of Fe clad and the like, and when a large amount of Fe clad flows into the reactor, complicated work such as drainage is performed after the reactor transient event has been completed successfully. And it is not easy to recover to normal operation. Further, even when the amount of suppression pool water is small, it cannot be said that it is preferable in terms of operation and maintenance.

It is an object of the present invention to use a condensate storage tank as a source of make-up water for reactor water during a reactor transient.
It is intended to facilitate a return to normal operation after the termination of a reactor transient.

[0013]

The above object can be attained as follows.

[0014]

[0015]

When reactor water level drops due to reactor transient
Replenish the reactor water when the reactor water is lost due to pipe rupture
Having a reactor water supply function,
A condensate storage tank storing water of the same quality as the reactor water, and the reactor water
Suppressors that store unfavorable water
Replenishment method for reactor water with reactor pool
Supply water from the suppression pool to the core.
A branch that drains part of the storage water from the middle of the supply pipe
A pipe is provided, and an electric valve is attached to the pipe and the branch pipe,
The water level of the suppression pool is equal to or higher than a specified value,
It is necessary to drain the water stored in the suppression pool.
When the stored water in the suppression pool is
So that water is drained through the downstream pump and heat exchanger.
Operate a motor-operated valve.

[0017]

According to the present invention, a logic circuit for switching the makeup water source from the condensate storage tank to the suppression pool is provided. That is, the high water level signal of the suppression pool and the reactor water loss signal are combined by an AND circuit, and the AND circuit and the low water level signal of the condensate storage tank are combined by an OR circuit.

According to the above-mentioned circuit, even if a suppression pool water level high signal is output during a reactor transient event, unless a reactor water loss signal or a condensate storage tank water level low signal is output,
The supply of make-up water to the core is not switched from the condensate storage tank to the suppression pool.

Therefore, during a reactor transient,
Only high signal of suppression pool, favorable for water quality
Water from the suppression pool does not flow into the furnace.
And not. It should be noted that the same effects as those described above
64-2233.

In a configuration satisfying the above-described functions.
Therefore, in the present invention, the water stored in the suppression pool is
Equipped with drainage facilities as needed. Therefore,
Timely space can be maintained above the compression pool
Caused by high water levels in the suppression pool
To maintain the function of suppressing the pressure vessel of the containment vessel.
it can.

[0021]

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

FIG . 1 is an explanatory view of an embodiment of the present invention, and FIG.
The reactor isolation cooling system related to one embodiment of the present invention
FIG. 4 is an explanatory diagram of a water source switching logic according to the embodiment.

In FIG . 2, inside the containment vessel 2,
Reactor pressure vessel 1, dry well 3, and suppression
Having pool 4, reactor water drop due to reactor transient
Sometimes, the electric valve A5 is open and the electric valve B6 is closed
Then, the water stored in the condensate storage tank 7 is atomized by the pump A8.
Refilling furnace pressure vessel.

Similarly, when the reactor water is lost due to a pipe break, the water stored in the condensate storage tank 7 is used with the electric valve A5 open and the electric valve B6 closed.

Then, the water level of the condensate storage tank 7 is measured using the condensate storage tank water level meter 10, and when the water level of the condensate storage tank 7 falls below a specified value, this is sensed. A signal to notify the low water level of the condensate storage tank 7 is transmitted, and this signal
The logic circuit closes the motor-operated valve A5 and opens the motor-operated valve B6 to switch the makeup water source, and the water stored in the suppression pool 4 flows into the reactor pressure vessel 1 by the pump A8.

The above logic circuit is shown in FIGS.
You. FIG. 3 is a flowchart of the makeup water source switching logic, and FIG.
It is a flow chart of valve train switching logic.

In each of FIGS. 3 and 4, the suppression
The high level signal of the pool and the reactor water loss signal are
In addition, this AND circuit and the water level low signal of the condensate storage tank 7
Fig. 3 shows the replenishment water source is condensed and stored.
When changing from the tank 7 to the suppression pool 4, FIG.
What is actually done to achieve the state of FIG.
That is, the state where the electric valve A5 is open and the electric valve B6 is closed
When the valve A5 is closed and the motor-operated valve B6 is opened
Are respectively shown.

According to the suppression pool water level meter 9,
Check that the water level in the suppression pool 4 has exceeded the specified value.
Is detected, the water level of the suppression pool 4 is raised.
A notification signal is transmitted. But in this state
To notify the loss of reactor water due to pipe breakage (L in FIG. 2).
Only when the OCA signal is transmitted, the logic of FIG.
The circuit closes the motor-operated valve A5 and opens the motor-operated valve B6.
As shown in the logic circuit of FIG.
The storage tank 7 is switched to the suppression pool 4.

Switching of the makeup water source while satisfying the conditions of FIG .
When performing the operation, the logic circuit shown in FIG. 4 is used.
If valve B6 does not open, motorized valve A5 will not close.
No. Therefore, the supply water source route will not be blocked
No water can be supplied continuously.

For each signal in the logic circuit of the present embodiment (low water level in the condensate storage tank, high water level in the suppression pool, loss of reactor water due to pipe breakage), an instrument is multiplexed, for example, 2OUT OF 3 By assembling logic or the like for each signal, malfunction due to a single failure of the instrument can be avoided.

In one embodiment of the present invention, the configuration as described above is used.
This was carried out in conjunction with the following. Figure 1 is a book
FIG. 3 is an explanatory view of an embodiment of the invention, and shows a sub-type shown in FIG.
In the replenishment system from the water pool to the core
The connection to the drainage system.

In FIG . 1, the condensate storage tank 7 (see FIG. 2)
While using as a makeup water source,
When the pool 4 becomes high, the suppression pool
The stored water of the fuel tank 4 has the electric valve C13 open and the electric valve D16
When the pump B14 is open and the electric valve E17 is closed.
The water is discharged through the heat exchanger 15.

In the above state, when a signal indicating a loss of reactor water due to a pipe break is transmitted, the suppression pool 4
The motor-operated valve D16 on the line leading to the drain of the stored water is closed, the motor-operated valve E17 is opened in synchronism with this, and the stored water in the suppression pool 4 is pumped through the heat exchanger 15 through the heat exchanger 15 by the pump B14. It is sent into the container 1.

As described above, the present invention is applicable to a reactor transient event.
Heat in the drainage means of the storage water in the suppression pool 4
The pump 14 of the residual heat removal system
The water stored in the suppression pool 4 is drained through the exchanger 15.
And the storage water of the suppression pool 4
It is not necessary to install a new heat exchanger for draining
No.

[0035]

According to the present invention, as a source of make-up water for reactor water during a reactor transient event, the water stored in the condensate storage tank is preferable in terms of water quality until the water level in the condensate storage tank falls below a specified value. Can be used to facilitate a return to normal operation after a safe termination of the reactor transient.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention.

FIG. 2 shows a makeup water source switching system according to an embodiment of the present invention .
It is an explanatory view of a trick.

FIG. 3 is a flowchart of a makeup water source switching logic of FIG . 2;
You.

FIG. 4 is a flowchart of the switching logic of the motor-operated valve of FIG . 2;
You.

FIG. 5 is an explanatory diagram of a conventional makeup water source switching logic.
You.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshio Kikuchi 3-1-1 Kochi-cho, Hitachi-shi, Ibaraki Pref. Sho 61-271497 (JP, A) JP-B 64-2-233 (JP, B2)

Claims (1)

(57) [Claims] 1. When the reactor water level drops due to a reactor transient event
And replenish the reactor water when the reactor water is lost due to pipe rupture
The reactor has a reactor water supply function to perform
Condenser storage tank storing water of the same quality as the storage water, and the furnace
Supplements that store unfavorable water in terms of water quality
Replenishment of reactor water with reactor pool
Supply water from the suppression pool to the core.
A branch that drains part of the storage water from the middle of the supply pipe
A pipe is provided, and an electric valve is attached to the pipe and the branch pipe,
The water level of the suppression pool is equal to or higher than a specified value,
It is necessary to drain the water stored in the suppression pool.
When the stored water in the suppression pool is
So that water is drained through the downstream pump and heat exchanger.
Reactor water replenishment characterized by operating a motorized valve
Method.