JPH02311794A - Emergency control device for nuclear reactor - Google Patents

Abstract

PURPOSE:To prevent a temperature rise of a heat exchanger by opening a by-pass pipe valve of the heat exchanger when an auxiliary cooling system is actuated and by sending a part of an auxiliary coolant into a heat exchanging chamber from a coolant path of the heat exchanger through the by-pass pipe. CONSTITUTION:When a nuclear reactor scram signal is output, a nuclear reactor 1 is stopped its operation and also each circulator 21, 36 and 47 of a heat exchanger 2 and coolers 3 and 4 for a pressurized water, is stopped. Then, simultaneously with an actuation of an auxiliary cooling system 5, a valve 23 of a by-pass pipe 22 is opened. An auxiliary coolant in a low temperature condition is sent to a reactor core 12 via a lower plenum part 11 of the nuclear reactor 1 to remove a decay heat in the reactor core. During this procedure, a part of the auxiliary coolant is also sent into a coolant feeder pipe 24 connected to a plenum part 11 and is sent to a heat exchanger 2 by flowing reversely through a pipe 24. At the heat exchanger 2, the auxiliary coolant in a low temperature condition (400 deg.C, for instance) is sent into a coolant flow path 20 betwee double barrel walls 16 and 17, and flows into a heat exchanging chamber 18 reversely to an ordinary direction, through a pipe 22, to cool down an inside and a container of the heat exchanger.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an emergency control device for a nuclear reactor, and particularly to a control device for cooling a nuclear reactor and a heat exchanger that extracts heat from its coolant in an emergency. Regarding.

"Conventional technology" Nuclear reactors are equipped with a reactor scram system that safely shuts down the reactor in the unlikely event that an abnormal situation occurs. , ■It assumes four stages of conditions in the event of a serious accident, and is controlled to operate after the stage (■). For example, in the case of a gas-cooled reactor, the operation of the nuclear reactor and the heat exchanger that exchanges heat between the coolant (for example, helium gas) heated in the reactor and the low-temperature fluid is stopped, The flow rate of the coolant in the coolant transport pipe and the coolant supply pipe connecting between the heat exchanger and the reactor is lost, and the auxiliary cooling system is activated to supplement the low temperature inside the reactor. Coolant can be pumped in to remove decay heat from the reactor.

"Problem to be Solved by the Invention" By the way, after the above-mentioned stage (①), auxiliary coolant is fed into the reactor, but the tubes and heat exchangers where the flow rate of the coolant has been lost are in a high temperature state. (e.g., 900° C. or higher), which may cause an increase in the temperature of these heat exchangers.

The present invention effectively solves the above-mentioned problems in a state in which the main cooling system after the above-mentioned stage (1) can be used. The purpose is to provide a time control device.

"Means for Solving the Problems" The present invention provides a coolant transport pipe that transports high-temperature coolant heated in a nuclear reactor, and a heat exchanger that exchanges heat between the high-temperature coolant and a low-temperature fluid. An exchanger, a coolant supply pipe that sends coolant in a low-temperature state to the reactor via the heat exchanger, and an auxiliary coolant that is sent into the reactor to remove decay heat during an emergency shutdown of the reactor. auxiliary cooling system, the heat exchanger has a cooling channel surrounding an internal heat exchange chamber and connected to the coolant supply pipe, and a coolant passing through the heat exchange chamber into the cooling channel. A circulator for sending the auxiliary cooling, a bypass pipe that bypasses the circulator and connects the heat exchange chamber and the cooling flow path, and a valve that opens and closes the flow path of the bypass pipe. It is characterized by being connected to a control system that opens the valve when the system is activated.

"Operation" When the reactor is brought to an emergency shutdown, the auxiliary cooling system is activated and auxiliary coolant is sent into the reactor, cooling the inside of the reactor and a portion of it flowing into the coolant supply pipe. It flows backwards towards the heat exchanger. In the heat exchanger, when the auxiliary cooling system is activated, the valve of the bypass pipe is opened, so that the auxiliary coolant in a low temperature state flowing from the reactor flows in the opposite direction to the normal flow, and the cooling flow path is After passing through the interior, it is sent through a bypass pipe into the heat exchange chamber, cooling the interior and the entire container.

``Embodiment'' Hereinafter, an embodiment of the emergency control device of the present invention will be described based on the drawings.

In the figure, reference numeral 1 indicates a nuclear reactor, 2 indicates a heat exchanger, 3 indicates a primary pressurized water cooler, 4 indicates a secondary pressurized water cooler, and 5 indicates an auxiliary cooling system.

In the illustrated example, the nuclear reactor 1 is a gas-cooled reactor that uses helium gas as a coolant, and has a bottom plenum section 11.
The coolant fed into the reactor core 12 is heated by the heat of the reactor core 12 while circulating inside. Code 13 is the reactor core 12
2 shows a control rod drive device that moves the control rod 14 inserted into the.

The heat exchanger 2 is an intermediate heat exchanger disposed between the reactor 1 and the secondary pressurized water cooler 4, and most of the container 15 is formed by double shell walls 16 and 17, and the inner side The interior space of the trunk wall 16 is used as a heat exchange chamber 18, and a helical coil-shaped heat exchanger tube 19 through which helium gas flows as a secondary coolant is disposed inside. In addition, double trunk wall 1
The space between 6 and 17 is a cooling channel 20, and the cooling channel 20
A circulator 21 is provided between the container 15 and the heat exchange chamber 18 to send the coolant, which has been brought into a low temperature state through heat exchange, from the heat exchange chamber 18 to the cooling flow path 20, so as to suppress the rise in temperature of the container 15. There is. Further, a bypass pipe 22 is provided that directly communicates the heat exchange chamber 18 and the cooling flow path 20 so as to bypass the circulator 21, and the bypass pipe 22 has a valve that opens and closes the flow path. 23 are provided. A coolant supply pipe 24 and a coolant transport pipe 25 having a double pipe shape are connected between the heat exchanger 2 and the nuclear reactor 1. In this case, the outer coolant supply pipe 24 is connected to the bottom plenum part 11 of the reactor 1, and the inner coolant transport pipe 25 is connected to the core 12.
The coolant that has reached a high temperature via the reactor core 12 is sent to the heat exchange chamber 18 through the coolant transport pipe 25, and the coolant that has become low temperature due to heat exchange is transferred to the cooling flow. From the channel 20, the coolant is fed into the bottom plenum section 11 of the reactor 1 through a coolant supply pipe 24.

The secondary processing water cooler 3 is connected to the nuclear reactor 1 by branching the coolant supply pipe 24 and the coolant transport pipe 25 in the middle and connecting to the tip thereof. , a U-shaped heat transfer tube 35 is housed in a heat exchange chamber 34 in a container 33 having double body walls 31 and 32 similar to the heat exchanger 2, and exchanges heat between the coolant and pressurized water, The coolant in a low temperature state is sent to a cooling channel 37 by a plurality of circulators 36, and then sent to the nuclear reactor 1 again. Reference numeral 38 indicates a pressurized water supply system, and reference numeral 39 indicates a pressurized water discharge system.

The secondary pressurized water cooler 4 includes a container 44 having a cooling passage 43 formed between double body walls 41 and 42, and a heat exchange chamber 4 thereof.
It has a U-shaped heat transfer tube 46, a circulator 47, a pressurized water supply system 48, a pressurized water discharge system 49, etc. housed in the heat exchanger 2, and has a double-tubular coolant supply pipe 50 and a cooling They are connected by a material transport pipe 51.

The auxiliary cooling system 5 is configured similarly to the secondary processing water cooler 3 and includes a coolant cooler 55 that cools the coolant with pressurized water, and a pressurized water cooling system 56 that cools the pressurized water. 1 by a double-tubular coolant supply pipe 57 and a coolant transport pipe 58. In this case too,
Similar to the coolant supply pipe 24 and the coolant transport pipe 25, the outer coolant supply pipe 57 is connected to the bottom plenum part 11, and the inner coolant transport pipe 25 is connected to the core 12. The high-temperature coolant that has passed through the coolant transport pipe 58 is drawn into the heat exchange chamber 60 in the container 59 of the coolant cooler 55, and is cooled by pressurized water flowing through the U-shaped heat transfer tube 61 therein. Double body wall 6 with circulator 62
After being sent into the cooling channel 65 between No. 3 and 64, it is sent to the bottom plenum portion 11 of the nuclear reactor 1. The pressurized water cooling system 56 sends the pressurized water in the coolant cooler 55 to the pressurizer 67 through the pressurized water discharge pipe 66, and then sends the pressurized water in the coolant cooler 55 to the air cooler 6.
8 and pressurized water supply pipe 70 with circulation pump 69.
The coolant is then sent to the coolant cooler 55 again.

This auxiliary cooling system 5, the control rod drive device 13 of the reactor 1, the heat exchanger 2, each circulator 21, 36, 47 of both pressurized water coolers 3, 4, and the bypass pipe 2 of the heat exchanger 2
The valve 23 in the reactor 1 is connected to a control system 71 that detects a pressure increase in the reactor 1 and outputs a scram signal, and is controlled as described later.

In the drawing, reference numeral 72 indicates a pressure boundary of the reactor containment vessel, and an isolation valve 73 is disposed on the outside of a pipe that passes through the pressure boundary 72. Reference numeral 74 is a stop valve, reference numeral 75
indicates a check valve.

Next, the control method will be explained.

When the reactor scram signal is output due to the occurrence of the above-mentioned stage (2), the control rod drive device 13 inserts all the control rods 14 into the reactor core 12, and the operation of the reactor 1 is stopped and heat exchange is performed. By stopping the circulators 21, 36 and 47 of the water cooler 2 and the pressurized water coolers 3 and 4, the flow rates in the coolant supply pipes 24 and 50 and the coolant transport pipes 25 and 51 are lost ( During this time, for example, about 10 seconds). Next, the auxiliary cooling system 5 is activated and the valve 23 of the bypass pipe 22 is opened. Then, the auxiliary coolant in a low temperature state is sent from the auxiliary cooling system 5 to the reactor core 12 via the bottom plenum portion 11 of the reactor 1, thereby removing internal decay heat. At this time, part of the auxiliary coolant sent into the bottom plenum part 11
The coolant is also sent into the coolant supply pipe 24 which is in communication with the coolant supply pipe 24 , flows backward through the coolant supply pipe 24 , and is sent to the heat exchanger 2 . In the heat exchanger 2, a low temperature state (for example, 4
00°C) is fed into the heat exchange chamber 18 via the bypass pipe 22 with the valve 23 in the open state.
The water flows into the tank in the opposite direction to the normal flow, cooling the interior and the container.

"Effects of the Invention" As is clear from the above description, the emergency control device of the present invention can provide the following effects.

(1) When the auxiliary cooling system is activated, the valve in the bypass pipe of the heat exchanger is opened, so some of the low-temperature auxiliary coolant that is sent into the reactor flows back through the coolant supply pipe and exchanges heat. It is sent into the heat exchange chamber from the cooling flow path of the heat exchanger via the bypass pipe, and can cool the inside and the entire container, preventing the temperature of the heat exchanger from rising and making it possible to stop the heat exchanger more safely. can.

(11) The heat exchanger is also cooled using the auxiliary coolant sent from the auxiliary cooling system for cooling the reactor, and the auxiliary cooling system is shared, simplifying the equipment. It is possible to streamline management, etc.

[Brief explanation of drawings]

The drawing is a piping system diagram showing one embodiment of the control device according to the present invention. ■... Nuclear reactor, 2... Heat exchanger, 3.
....-Next processing water cooler, 4...Secondary pressurized water cooler, 5...Auxiliary cooling system, 11...
・Bottom plenum part, 12... Core, 13...
... Control rod drive device, 14 ... Control rod, 15
... Container, 16/17 ... Trunk wall, 18
... Heat exchange chamber, 19 ... Heat exchanger tube, 20
... Cooling channel, 21 ... Circulatory system, 22
...Bypass pipe, 23...Valve, 24.
... Coolant supply pipe, 25 ... Coolant transport pipe, 31, 32 ... Shell wall, 33 ... Container, 34 ... heat exchange chamber, 35... heat exchanger tube,
36...Circulatory system, 37...Cooling channel, 3
8... Pressurized water supply system, 39... Pressurized water discharge system, 41, 42... Body wall, 43...
・Cooling channel, 44... Container, 45...
Heat exchange chamber, 46... Heat exchanger tube, 47... Circulator, 48... Pressurized water supply system, 49...
- Pressurized water discharge system, 50... Coolant supply pipe, 51
... Coolant transport pipe, 55 ... Coolant cooler, 56 ... Pressurized water cooling system, 57 ...
Coolant supply pipe, 58... Coolant transport pipe, 59.
... Container, 60 ... Heat exchange chamber, 61 ...
... Heat exchanger tube, 62 ... Circulatory system, 63/64
..... Trunk wall, 65.. ... Cooling channel, 66.
... Pressurized water discharge pipe, 67 ... Pressurizer, 6
8... Air cooler, 69... Circulation pump, 70... Pressurized water supply pipe, 71...
Control system, 72... Voltage boundary, 73...
... Isolation valve, 74 ... Stop valve, 75 ...
··non-return valve.

Claims (1)

[Claims] A coolant transport pipe that transports high-temperature coolant heated in a nuclear reactor, a heat exchanger that exchanges heat between the high-temperature coolant and low-temperature fluid, and a low-temperature fluid that passes through the heat exchanger. The heat exchanger has a coolant supply pipe that sends the coolant that has become in a state of , a cooling channel that surrounds the internal heat exchange chamber and is connected to the coolant supply pipe; a circulator that feeds the coolant via the heat exchange chamber into the cooling channel; and a circulator that bypasses the circulator. A bypass pipe that communicates the heat exchange chamber and the cooling flow path, and a valve that opens and closes the flow path of the bypass pipe are provided, and a control system that opens the valve when the auxiliary cooling system is activated is connected to the valve. An emergency control device for a nuclear reactor characterized by: