JP2003270374A - Containment spray control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a containment spray control device capable of suppressing automatically increase of a pressure and a temperature in a nuclear reactor containment in a core reflooding process at the loss time of a nuclear reactor coolant in a nuclear power plant. <P>SOLUTION: A nuclear reactor containment pressure high signal 27 and a reactor water level below-TAF signal 28 are received by a signal reception part 29, and a condensate-replenishing water pump 18 or a fire-fighting system pump 21 which is an alternative water injecting facility is driven by realization of a logic condition in a control part, and an alternative water injecting facility delivery valve 19, a dry well spray injection isolation valve 13 and a dry well spray flow adjusting valve 14 are opened, to thereby spray water in a condensate storage tank 20 or a filtrate tank 22 into a nuclear reactor containment dry well 3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactor containment vessel spray cooling function of a reactor containment vessel heat removal system for reducing the pressure and temperature in the reactor containment vessel of a nuclear power plant.

[0002]

2. Description of the Related Art In a conventional nuclear power plant,
In the unlikely event that the piping connected to the reactor pressure vessel breaks during power output operation of the reactor, the high temperature reactor coolant will flow out of the reactor pressure vessel due to the fracture, and the cooling capacity of the reactor core will decrease. Even if (hereinafter referred to as LOCA) occurs, the emergency core cooling system is promptly activated to start water injection into the reactor pressure vessel, and the core can be cooled to prevent serious damage to fuel. ing.

Further, when the pressure and temperature in the reactor containment vessel rise due to energy such as coolant or decay heat released into the reactor containment vessel at the time of LOCA, the heat removal system for the reactor containment vessel is manually operated. After starting up, heat exchange between the suppression pool water and the secondary cooling water is performed to remove heat from the suppression pool water, and at the same time, the cooled suppression pool water is sprayed into the reactor containment vessel for steam in the reactor containment vessel. And heat exchange with the atmosphere,
The pressure and temperature inside the reactor containment vessel can be reduced. The spray water warmed by this condensed water and heat exchange flows into the suppression pool,
The heat removal system of the PCV can remove and cool the heat.

When the reactor containment heat removal system for reducing the pressure and temperature in the reactor containment vessel cannot be used, an alternative water injection system composed of a condensate make-up water system or a fire extinguishing system is manually started. However, the pressure and temperature in the reactor containment vessel can be lowered by spraying the water in the condensate storage tank or the water in the filtered water tank into the reactor containment vessel.

FIG. 6 is a schematic system diagram of an emergency core cooling system, a reactor containment heat removal system and an alternative water injection system which are activated at the time of LOCA. A reactor pressure vessel 1 and a recirculation pipe 4 are stored, and a reactor containment vessel 2 having a configuration in which a reactor containment vessel dry well 3 and a suppression pool 5 are connected by a vent pipe 6 and a suppression pool 5 as a water source, An emergency core cooling system having a suction pool side suction valve 24, an emergency core cooling system pump 23, and an emergency core cooling system injection isolation valve 25, and a reactor containment heat removal system pump 7 using the suppression pool 5 as a water source. Core injection for injecting water into the reactor pressure vessel 1 from the reactor containment vessel heat removal system piping 12 having an exchanger 8, a heat exchanger outlet valve 10, a heat exchanger bypass pipe 9, and a heat exchanger bypass valve 11. Injection isolation valve 15, drywell spray injection isolation valve 13 for spraying into the reactor containment drywell 3, and drywell spray flow control valve 14 Suppression pool spray injection isolation valve 16 for spraying into the suppression pool 5 and a reactor containment heat removal system having a suppression pool injection isolation valve 17 for injecting into the suppression pool 5 and a condensate storage tank 20 as water sources It has a condensate makeup water system pump 18 and a fire extinguishing system pump 21 that uses a filtered water tank 22 as a water source, and the heat removal system piping 12 for the containment vessel
In the configuration of the prior art, which has an alternative water injection facility outlet valve 19 for connecting to the
When LOCA that breaks the recirculation pipe 4 connected to the reactor, the coolant in the reactor pressure vessel 1 flows out to the dry well 3 of the reactor containment vessel 2. The flowing-out coolant then reaches the suppression pool 5 through the vent pipe 6.

The reactor water level in the reactor pressure vessel 1 is lowered by the outflow of the coolant. Further, the pressure and temperature in the reactor containment vessel 2 rise due to the inflow of the coolant. At this time, the emergency core cooling system is started by the signal of low reactor water level or high reactor containment vessel pressure.

The emergency core cooling system includes a high pressure system and a low pressure system. When the pressure inside the reactor pressure vessel 1 is high, the suppression pool 5 is used as a water source and the suction pool side suction valve 24 and the emergency core cooling system pump 23 are used. , Injection into the reactor pressure vessel 1 through the emergency core cooling system injection isolation valve 25. When the pressure inside the reactor pressure vessel 1 is low, the suppression pool 5 is used as a water source for the reactor containment vessel heat removal system pump 7, the heat exchanger bypass pipe 9, the heat exchanger bypass valve 11, the reactor containment vessel heat removal system. Piping 12,
Water is injected into the reactor pressure vessel 1 through the core water injection injection isolation valve 15. As a result, the core in the reactor pressure vessel 1 can be continuously cooled to prevent serious damage to the fuel.

When the pressure and temperature in the reactor containment vessel 2 rise due to energy such as decay heat released into the reactor containment vessel during LOCA, heat removal from the reactor containment vessel using the suppression pool 5 as a water source. The system pump 7 is started, the heat exchanger outlet valve 10 is opened, the heat exchanger bypass valve 11 is closed, and the heat exchanger 8 exchanges heat between the suppression pool water and the secondary cooling water to remove it from the suppression pool. Heat-cooled, drywell spray injection isolation valve 13,
The suppression pool water is sprayed into the reactor containment vessel 2 by opening the drywell spray injection control valve 14 and the suppression pool spray injection isolation valve 16 and closing the core water injection injection isolation valve 15. As a result, the vapor in the reactor containment vessel 2 can be condensed and heat can be exchanged from the atmosphere, and the pressure and temperature in the reactor containment vessel 2 can be reduced.

In the unlikely event that the reactor containment vessel heat removal system cannot carry out the reactor containment vessel spraying,
The condensate makeup water pump 18 or the fire extinguishing system pump 21 is started by manual operation, the alternative water injection facility outlet valve 19, the drywell spray injection isolation valve 13, and the drywell spray injection control valve 14 are opened, and the condensate storage tank 20 is opened. Alternatively, by spraying the water in the filtered water tank 22 into the dry well 3 of the reactor containment vessel, the vapor in the reactor containment vessel 2 is condensed and heat is exchanged from the atmosphere, so that the pressure and temperature in the reactor containment vessel 2 are controlled. Can be lowered.

Japanese Patent Application Laid-Open No. 9-105795 discloses a conventional technique for suppressing an increase in pressure and temperature in the reactor containment vessel by spraying water into the reactor containment vessel.
There is a bulletin, etc.

[0011]

[Patent Document 1] Japanese Unexamined Patent Publication No. 9-10579
In the prior art of Japanese Patent No. 5 publication, an operator of the nuclear power plant manually starts the fire extinguishing system in the unlikely event of damage to the reactor pressure vessel due to the fire extinguishing system function improvement measure that temporarily stores the water of the fire extinguishing system, By spraying a large amount of water into the reactor containment vessel, it is possible to improve the decontamination effect of gaseous radioactive substances by reducing the sprayed droplets and to suppress the pressure and temperature inside the reactor containment vessel. ing.

When this conventional technique is used, the LO
When CA occurs and the injection of water by the emergency core cooling system is delayed and the core is re-submerged after the core is exposed, first the temperature of the fuel rises due to the exposure of the core, and then the fuel is re-submerged by the re-submersion of the core. The heat of heat is transferred to the coolant to lower the fuel temperature, while a large amount of high-temperature steam is generated and steam flows out from the broken pipe to the PCV drywell. And the temperature rises. At this time, it is kept within the limit value that affects the soundness of the reactor containment drywell, but the margin for the limit value is reduced.

An object of the present invention is to generate atoms in the process of core re-flooding after core exposure when multiple failures occur with a very small occurrence probability such as delay of water injection by the emergency core cooling system after occurrence of LOCA. An object of the present invention is to provide a containment vessel spray control device capable of automatically suppressing an increase in pressure and temperature in a dry well of a containment vessel of a furnace.

[0014]

To achieve the above object, the present invention provides a reactor containment vessel for storing a reactor pressure vessel, an emergency core cooling system, and a reactor containment heat removal system. , A condensate make-up water system and a fire extinguishing system, and in a nuclear power plant capable of spraying an alternative reactor containment vessel by means of an alternative water injection system connected to the heat removal system of the reactor containment vessel Reactor water level is TAF
(Available fuel rod top) A signal receiving unit for receiving the following signals,
Depending on the signal received by the signal receiving unit, the start signal of the condensate makeup water pump and the fire extinguishing system pump of the alternative water injection equipment, the opening signal of the alternative water injection equipment outlet valve, the heat removal system of the reactor containment vessel to which the alternative water injection equipment is connected Equipped with a control unit that automatically outputs an open signal of the drywell spray injection isolation valve and drywell spray flow control valve, and a closing signal of the core water injection injection isolation valve, and these signals are used in the condensate storage tank or the filtered water tank. Spray cold water from the reactor into the containment vessel.

With this configuration, when LOCA is generated and the reactor water level becomes lower than TAF, the reactor containment vessel spray by the alternative water injection equipment is automatically activated to cool the reactor containment vessel to a low temperature. By spraying this water prior to the re-submersion of the core, it is possible to condense the steam generated during the re-submersion of the core and flowing out into the reactor containment vessel to suppress the rise in the pressure and the temperature.

Further, in the above construction, in the present invention, in addition to the reactor containment vessel high pressure signal and the reactor water level TAF or lower signal, a signal receiving section for receiving an emergency core cooling system start signal and this signal are used for alternative water injection. Start signal for the condensate make-up water pump and fire extinguishing system pump, open signal for the alternative water injection equipment outlet valve, dry well spray injection isolation valve and dry well spray for the heat removal system of the reactor containment vessel to which the alternative water injection equipment is connected A control unit that automatically outputs an open signal of the flow control valve and a close signal of the core water injection injection isolation valve is provided, and low temperature water in the condensate storage tank or the filtered water tank is put in the reactor containment vessel by these signals. Characterized by spraying.

With this configuration, it is detected that LOCA has occurred, the reactor water level has fallen below TAF, and that water injection into the reactor pressure vessel has started, and automatic spraying of the reactor containment vessel by means of alternative water injection equipment is performed. By spraying low-temperature water into the reactor containment vessel prior to core re-submersion, the steam generated during core re-submersion is condensed to increase the pressure and temperature. Can be suppressed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The same components as those of the above-mentioned conventional technique are designated by the same reference numerals and detailed description thereof will be omitted.

As shown in FIG. 1, a signal receiving unit 29 for receiving the reactor containment vessel high pressure signal 27 and the reactor water level TAF or less signal 28, a control unit 30 for processing the signal according to the internal logic, and pumps and valves are operated. Condensate make-up water system pump start signal 31, fire extinguishing system pump start signal 32, alternative water injection facility outlet valve open signal 33, drywell spray injection isolation valve open signal 34, drywell spray flow control valve open signal 35, core water injection injection It is constituted by each output signal of the isolation valve closing signal 36.

FIG. 2 shows an example of logic in the control unit 30. This logic has an AND circuit 37 and a timer circuit 38 that connect the reactor containment vessel high pressure signal 27 and the reactor water level TAF or lower signal 28, and a condensate make-up water system pump start signal 31.
Fire extinguishing system pump start signal 32, alternative water injection facility outlet valve open signal 33, drywell spray injection isolation valve open signal 34, drywell spray flow control valve open signal 35, core water injection injection isolation valve closed signal 36 It

Specific examples will be described below. L
When OCA occurs, the signal receiving unit 29 receives both the reactor containment vessel high pressure signal 27 and the reactor water level TAF below-signal 28, and inputs them to the AND circuit 37 of the control unit 30. Here, the reactor containment pressure high signal 27 may be a reactor containment temperature high signal.

Since both signals are input at the same time, the AN
The D circuit 37 outputs a signal to the timer circuit 38. The timer circuit 38 confirms that the output signal from the AND circuit 37 continues for a fixed time. As a result, the time until the fuel temperature rises after the core is exposed is set, the rise in fuel temperature is detected, and unnecessary ON-OFF operation of signals is prevented.

From this timer circuit 38, a condensate makeup water system pump start signal 31, a fire extinguishing system pump start signal 32, an alternative water injection facility outlet valve open signal 33, a drywell spray injection isolation valve open signal 34, and a drywell spray flow control valve open. By outputting the signal 35 and the core water injection injection isolation valve closing signal 36 to start the pumps to be controlled and open / close the valves, the alternative reactor containment vessel spray by the alternative water injection equipment becomes possible.

In this embodiment, the signal high pressure signal 27 for the reactor containment vessel and the signal 28 for the reactor water level TAF or lower are received by the signal receiving section. However, the pressure signal for the reactor containment vessel and the signal for the reactor water level are respectively received. May be received by the signal receiving unit and passed to the control unit, and the control unit may compare with the set value of the reactor containment pressure high and the reactor water level TAF or lower.

In another embodiment, as shown in FIGS. 3 and 4, in addition to the reactor containment vessel high pressure signal 27 and the reactor water level TAF lower signal 28, an emergency core cooling system start signal 26 is received. It is received by the unit 29. As a result, it is detected that the exposed core is submerged again. The signal from the signal receiving unit 29 is input to the AND circuit 37 of the control unit 30.
Here, the reactor containment pressure high signal 27 may be a reactor containment temperature high signal. The emergency core cooling system activation signal may be a pump activation signal, a system flow rate signal, or a pump discharge pressure signal.

The AND circuit 37 outputs signals to the timer circuit 38 by the simultaneous input of these signals.
The timer circuit 38 confirms that the output signal from the AND circuit 37 continues for a fixed time. As a result, the time until the fuel temperature rises after the core is exposed is set, the rise in fuel temperature is detected, and unnecessary ON-OFF operation of signals is prevented.

From this timer circuit 38, a condensate makeup water system pump start signal 31, a fire extinguishing system pump start signal 32, an alternative water injection facility outlet valve open signal 33, a drywell spray injection isolation valve open signal 34, and a drywell spray flow control valve open. By outputting the signal 35 and the core water injection injection isolation valve closing signal 36 to start the pumps to be controlled and open / close the valves, the alternative reactor containment vessel spray by the alternative water injection equipment becomes possible.

In this embodiment, the signal high pressure signal 27 of the reactor containment vessel and the signal 28 below the reactor water level TAF are received by the signal receiving section. However, the pressure signal of the reactor containment vessel and the signal of the reactor water level are respectively received. , Emergency core cooling system flow rate signal or pump discharge pressure signal is received by the signal receiving unit and passed to the control unit, and the control unit controls the reactor containment vessel pressure high, reactor water level below TAF, and emergency core cooling system system The logic may be compared with the set value of the flow rate high or the discharge pressure high of the pump.

FIG. 5 shows the behavior of the pressure inside the containment vessel during LOCA. The solid line represents the effect of the present invention, and the broken line represents the conventional technique. The behavior of the internal pressure of the reactor containment vessel 2 shown here is in the unlikely event that a part of the core is exposed due to delay of water injection by the emergency core cooling system or the like for some reason.

The behavior of the reactor containment vessel pressure is as follows: high-temperature coolant inflow process f from the reactor coolant loss occurrence a to the reactor water level recovery start c due to the start of water injection by the emergency core cooling system f, the reactor Core re-flooding process g from water level recovery start c to core re-flooding d, spray water inflow process h from core re-flooding d to reactor containment vessel cooling start e by the reactor containment heat removal system h, containment It is divided into the reactor containment vessel cooling process i after the reactor containment vessel cooling start e by the vessel heat removal system.

By applying the present invention, core exposure b
The increase in the reactor containment vessel pressure in the subsequent core re-submersion process g is greatly reduced as compared with the pressure behavior according to the prior art. The same effect can be expected with respect to temperature.

The contents of the present invention are not limited to the above-mentioned embodiment, and the input / output signals and control logic of the control device can be applied to the nuclear power plant having different system configuration of the emergency core cooling system and different reactor containment vessel types. It is possible to partially change and apply.

[0033]

According to the present invention, it is possible to automatically suppress the rise in the pressure and temperature in the reactor containment vessel during the core resubmersion process at the time of LOCA by using the alternative water injection facility.

[Brief description of drawings]

FIG. 1 is a schematic system diagram of an embodiment of a containment vessel spray control device according to the present invention.

2 is a diagram showing the control logic of FIG. 1. FIG.

FIG. 3 is a schematic system diagram of another embodiment of the containment vessel spray control device according to the present invention.

FIG. 4 is a diagram showing the control logic of FIG. 3;

FIG. 5 is a diagram showing the behavior of the pressure inside the containment vessel during LOCA.

FIG. 6 is a schematic system diagram of an emergency core cooling system, a reactor containment heat removal system, and an alternative water injection facility that are activated at the time of LOCA.

[Explanation of symbols]

1 ... Reactor pressure vessel, 2 ... Reactor containment vessel, 3 ... Reactor containment vessel dry well, 4 ... Recirculation piping, 5 ... Suppression pool, 6 ... Vent pipe, 7 ... Reactor containment vessel heat removal system pump, 8 ... Heat exchanger, 9 ... Heat exchanger bypass piping, 10 ... Heat exchanger outlet valve, 11 ... Heat exchanger bypass valve, 12 ... Reactor containment vessel heat removal system piping, 13 ... Drywell spray injection isolation valve, 14 ... Drywell spray flow control valve, 15 ... Core water injection injection isolation valve, 16 ... Suppression pool spray injection isolation valve, 17 ... Suppression pool injection isolation valve, 18 ... Condensate makeup water system pump,
19 ... Alternative water injection equipment outlet valve, 20 ... Condensate storage tank, 21 ...
Extinguishing system pump, 22 ... Filtration water tank, 23 ... Emergency core cooling system pump, 24 ... Suppression pool side suction valve, 25
... Emergency core cooling system injection isolation valve, 26 ... Emergency core cooling system start signal, 27 ... Reactor containment vessel high pressure signal, 28 ...
Reactor water level TAF or lower signal, 29 ... Signal receiving unit, 30 ...
Control part, 31 ... Condensate replenishing water system pump start signal, 32 ... Fire extinguishing system pump start signal, 33 ... Alternative water injection facility outlet valve open signal, 34 ... Drywell spray injection isolation valve open signal, 3
5 ... Drywell spray flow rate control valve open signal, 36 ... Core water injection injection isolation valve close signal, 37 ... AND circuit, 38 ... Timer circuit, a ... Reactor coolant loss occurrence, b ... Core exposure, c ... Reactor Water level recovery started, d ... Achievement of core re-flooding, e
... Restart of reactor containment vessel cooling by reactor containment heat removal system, f ... High temperature coolant inflow process, g ... Re-core flooding process, h
... spray water inflow process, i ... reactor containment vessel cooling process.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hitoshi Sakuma             Hitachi 2-3-1, Saiwaicho, Hitachi-shi, Ibaraki             Engineering Co., Ltd. F-term (reference) 2G002 AA03 BA01 BA07 DA01 EA04

Claims (2)

[Claims] 1. A reactor containment vessel for containing a reactor pressure vessel, an emergency core cooling system, and a reactor containment vessel heat removal system,
In the containment vessel spray control device of the nuclear power plant, which is capable of spraying the alternative reactor containment vessel by means of an alternative water injection system that is composed of a condensate makeup water system and a fire extinguishing system, and is connected to the heat removal system of the reactor containment vessel, A signal receiving unit that receives a signal indicating that the pressure has dropped and a signal indicating that the reactor containment pressure has risen, and a valve of the reactor containment heat removal system and an alternative water injection facility based on the signal received by the signal receiving unit. A containment vessel spray control device comprising a control unit for automatically operating a valve and a pump. 2. The valve of the reactor containment heat removal system according to claim 1, wherein the signal receiving unit receives an emergency core cooling system activation signal, and the control unit uses the signal received by the signal receiving unit. , Containment spray control device that automatically operates valves and pumps of alternative water injection equipment.