JPH04140696A - High pressure core cooling system - Google Patents

Abstract

PURPOSE:To upgrade reliability and improve safety of nuclear reactor by switching water source from a suppression pool to a condensation resorvoir tank automatically in the case of abnormal temperature elevation of the suppression pool water. CONSTITUTION:Normally a condensation resorvoir tank is used as water source at first, and by the signal of low water level in the condensation resorvoir tank 5 or high water level in a suppression pool 4, a water source switch control circuit 16 completely opens an electric motor operated valve 9 and closes an electric motor operated valve 8 to switch the source for cooling water from the tank 5 to the pool 4. Next, if the suppression pool is used as water source for cooling and the temperature of the suppression pool water rises, a water temperature detector 15 detects the abnormality. When the signal of the detector 15 exceeds predetermined value and the signal of water level detector 14 in the tank 5 exceeds a predetermined value, an opening command is sent to the valve 8 and a closing command is sent to the valve 9 to automatically switch the water source for cooling from the pool 4 to the tank 5. Therefore, continuous water supply to the reactor becomes possible and the safety of the reactor is attained.

Description

Detailed Description of the Invention [Purpose of the Invention (Industrial Application Field) The present invention relates to a core cooling system that replenishes cooling water to a reactor core in order to maintain the health of a nuclear reactor. This article relates to a high-pressure core cooling system for a reactor.

(Prior Art) A boiling water reactor is equipped with an emergency core cooling system that supplies cooling water to ensure the safety of the reactor when the water level of the reactor drops abnormally.

As part of such an emergency core cooling system, a high pressure core cooling system of a high pressure water injection system (HPCI) is installed, which is capable of supplying cooling water even when the reactor is under high pressure.

FIG. 3 is a system configuration diagram of a high pressure water injection system (HPCI), which is one of the conventional high pressure core cooling systems.

As shown in the figure, feed water supplied to the nuclear reactor 1 via the water supply system is heated here and turned into steam, which is then supplied to the turbine. The steam that has done work in the turbine becomes condensed water in the condenser and is returned to the reactor via the water supply system. A high-pressure water injection system (HPCI), which is one type of high-pressure core cooling system, is equipped with condensate storage tank water or suppression pool water as a cooling water source, but usually condensate storage tank water is used.

The rainwater source is switched by the water source switching control circuit 12. That is, as shown in the logical circuit diagram of FIG. 4, the valve 9 is fully opened when the water level of the condensate storage tank is low or the water level of the subtraction pool is high, and the cooling water source is transferred from the condensate storage tank 5 to the suppression pool by closing the valve 8. Switch to 4.

In response to an abnormally low water level signal in the reactor 1 or an abnormally high pressure signal in the dry well 2, the water source switching control circuit 12 is automatically activated to open the valve 8 or 9, and the tank water in the condensate storage tank 5 or the suppression pool is automatically activated. Pressurize the pool water from No. 4 with pump 7, open valve 11, and transfer it from the water supply system to reactor No. 1.
It is configured to supply Further, the driving turbine 6 of the pump 7 is supplied with a portion of the steam generated in the nuclear reactor 1 via a valve 10 . The water level of the suppression pool 4 in the pressure suppression chamber 3 is detected by a water level detector 13, and the water level of the condensate storage tank 5 is detected by a water level detector 14.

By the way, if a transient change such as a loss of water supply occurs due to equipment failure, etc., and the reactor water level drops abnormally, the high-pressure water injection system (HPCI) will automatically start, as mentioned above, and the water in the condensate storage tank will be The integrity of the reactor is maintained by supplying it to the reactor 1. On the other hand, the steam generated by the decay heat of the core is released into the suppression pool water through the safety relief valve, where it is cooled and condensed, causing the suppression pool water level to rise much faster than the condensate storage tank water level low signal is generated. At this point, a suppression pool water level high signal is generated, the water source is switched to the suppression pool water, and the Subleon pool water is used for circulation from then on. In addition, the suppression pool water is cooled by the containment vessel cooling system, suppressing the increase in pool water temperature due to decay heat, and ensuring the safety of the reactor.

(Problem to be Solved by the Invention) By the way, when the high pressure water injection system (HPCI) is operated using suppression pool water as a water source, the containment vessel cooling system is multiplexed, but suppression may occur due to some reason. If a situation occurs where pool water cannot be cooled, the suppression pool water temperature will rise above the design temperature of the high pressure water injection system (HPCI), and in the worst case, the cooling water supply of the high pressure water injection system (HPCI) will be interrupted. Capacity may be lost.

The present invention has been made in view of the above circumstances, and its purpose is to provide a high-pressure core cooling system that automatically switches the water source from suppression pool water to condensate storage tank water when the suppression pool water temperature rises abnormally. Our goal is to provide the following.

[Structure of the Invention] (Means and Means for Solving the Problems) In order to achieve the above objects, the present invention provides a boiling water nuclear power plant that alternately uses suppression pool water and condensate storage tank water as a cooling water source. In a high-pressure core cooling system, when suppression pool water is used as a cooling water source, when the suppression pool water temperature is above the set temperature and the condensate storage tank water level is above the set water level, the cooling water source is changed from the suppression pool water to condensate storage. The water source is characterized by being equipped with a water source switching control circuit that switches to tank water.

(Example) Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration diagram of an embodiment of the present invention, and the same parts as in the conventional example are given the same reference numerals and will be explained.

In the figure, feed water supplied to the nuclear reactor 1 via the water supply system is heated here and turned into steam, which is then supplied to the turbine. The steam that has done work in the turbine becomes condensed water in the condenser and returns to the reactor via the water supply system, as in the conventional system.

The high-pressure water injection system (HP (1), which is one of the high-pressure core cooling systems to ensure the safety of the reactor, is automatically started according to the logical conditions shown in Figure 2, which will be described later), and the condensate storage tank 5 tank water or pool water in the suppression pool 4 is pressurized by a turbine drive pump 7 and is supplied to the nuclear reactor 1.

In addition, the pump 7 is driven by the condensate storage tank water level detector I4.
, a water source switching control circuit 15 that generates open/close signals to the outlet valves 8.9 of each water source according to signals from the suppression pool water level detector 13 and the suppression pool water temperature detector 15.
Switched by

FIG. 2 is a logic circuit diagram showing the operating principle of the water source switching control circuit 16 in the present invention.

Usually condensate storage tank water is used as the water source first,
In response to a signal indicating a low water level in the condensate storage tank 5 or a high water level in the suppression pool 4, the water source switching control circuit 16 fully opens the valve 9 and closes the valve 8 to switch the cooling water source from the condensate storage tank 5 to the suppression pool. It can be switched to 4.

Next, when the suppression pool water temperature rises when the suppression pool water is used as a cooling water source, the pool water temperature detector 15 detects an abnormality, and the signal of this water temperature detector 15 is determined in advance. When the signal from the water level detector 14 of the condensate storage tank 5 exceeds a predetermined set value, an open command is issued to the valve 8, and a close command is issued to the valve 9. , automatically switches the cooling water source from the suppression pool to the condensate storage tank. Therefore, even if the suppression pool water temperature rises when the suppression pool water is used as a water source, it will be possible to continue supplying cooling water to the reactor, which will improve the safety of the reactor. Secured.

[Effects of the Invention] As described above, according to the high-pressure core cooling system of the present invention, even when the suppression pool water temperature rises abnormally and exceeds the design temperature of the high-pressure core cooling system, the high-pressure core cooling system automatically operates without relying on operator operations. Since the water source can be switched from the suppression pool water to the condensate storage tank water, the reliability of the high-pressure core cooling system can be increased and the safety of the reactor can be improved.

[Brief explanation of the drawing]

Fig. 1 is a system configuration diagram of an embodiment of the present invention, Fig. 2 is a logic circuit diagram of a cooling water source switching control circuit which is the main part of the invention, and Fig. 3 is a system configuration of a conventional high-pressure core cooling system. Figure, 4th
The figure is a logic circuit diagram of a water source switching control circuit of a conventional high-pressure core cooling system. 1... Nuclear reactor 2... Dry well 3... Pressure suppression chamber 4... Suppression pool 5... Condensate storage tank 6... Pump driving turbine 7... Pump 8, 9. 10.11...Electric valve +2.1.6...Water source switching control circuit 1.3.14...Water level detector 15...Water temperature detector (8733) Agent: Patent attorney Yoshiaki Inomata ( others
1 person) Figure Figure

Claims (1)

[Claims] (1) In a high-pressure core cooling system of a boiling water nuclear power plant that uses suppression pool water and condensate storage tank water as a cooling water source by switching between them, when the suppression pool water is being used as a cooling water source, the suppression pool water temperature is lower than the set temperature. A high-pressure core cooling system characterized by comprising a water source switching control circuit that switches a cooling water source from suppression pool water to condensate storage tank water when the water level of the condensate storage tank is above a set water level.