JP3892193B2 - Reactor containment vessel water injection equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water injection facility in a nuclear power plant, and more particularly to a reactor containment water injection facility provided in preparation for a nuclear accident.
[0002]
[Prior art]
In a nuclear power plant using a boiling water reactor, an ECCS (Emergency Core Cooling System) is provided in preparation for the occurrence of an emergency such as coolant spillage due to the breakage of piping connected to the reactor pressure vessel. is there.
[0003]
This ECCS, also called an emergency core cooling system, is composed of a high pressure core cooling system, an automatic decompression system, and a low pressure core water injection mode that is one of the functions provided in the residual heat removal system, and an emergency has occurred. In some cases, the nuclear reactor is brought to an emergency shutdown, and the core is submerged by water injection from the ECCS so that the core is cooled rapidly.
[0004]
FIG. 7 shows an example of a reactor containment vessel 25 according to the prior art. The reactor containment vessel 25 is divided into an upper space and a lower space, and the reactor pressure vessel 23 is accommodated in the upper space. The D / W (dry well) 26 is used, the lower space is a W / W (wet well) 27 and a pressure suppression chamber 30, and the coolant flows out due to the breakage of the pipe connected to the reactor pressure vessel 23. When this occurs, the reactor core 24 is submerged by injecting the coolant together with the emergency stop of the reactor so that the reactor core 24 is cooled.
[0005]
Here, the ECCS high-pressure core cooling system is composed of a high-pressure core cooling pump 32, a pipe 35, valves 33a, 33b, 34a, 34b, a strainer 31a, and the like. The pool water in the suppression chamber 30 is switched by opening and closing the high pressure core cooling pump suction valves 33a and 33b, and both can be used as a water source.
[0006]
Next, the automatic decompression system opens the main steam relief safety valve 37 when the pressure in the reactor pressure vessel 23 rises greatly, such as when the high pressure core cooling system is inoperable, and the operation mode 1 of the residual heat removal system. It has a function of rapidly depressurizing to a pressure at which core water injection is possible in the low pressure core water injection mode.
[0007]
In this low pressure core water injection mode, the residual heat removal pump suction valve 39, the residual heat removal pump 38, the residual heat removal pipe 41, the heat exchanger 42, the heat exchanger switching valves 43a and 43b, the low pressure core water injection valve 40a, the strainer 31b, Devices up to 40b, dry well spray valve 45, wet well spray valve 47, dry well spray header 46, and wet well spray header 48 are used.
[0008]
When the reactor pressure vessel 23 is cooled in the low pressure core water injection mode, the pool water in the pressure suppression chamber 30 is used as a water source, and the reactor pressure vessel 23 is supplied by the residual heat removal pump 38 via the low pressure core water injection valves 40a and 40b. It is designed to inject water.
[0009]
Next, the residual heat removal system is provided to remove heat from the reactor containment vessel 25 and suppress the pressure and temperature rise of the reactor containment vessel 25. For this reason, the cooling cooled by the heat exchanger 42 is performed. Water is sprayed from the spray headers 46 and 48 to the D / W 26 and W / W 27. At this time, the heat exchanger 42 performs cooling operation by the cooling water sent by the auxiliary machine cooling pump 44. Do.
[0010]
In such an emergency, the cooling water flowing out of the reactor pressure vessel 23 and the cooling water sprayed in the D / W 26 return to the pressure suppression chamber 30 through the vent pipe 28 and are stored as pool water. After that, it is used again as cooling water.
[0011]
Here, the bent pipe 28 has a broken line A in preparation for a case where the pressure in the D / W 26 is rapidly reduced by the D / W spray and the pressure in the W / W 27 becomes higher than the pressure in the D / W 26. A vacuum break valve 29 </ b> A is provided as enclosed in FIG.
[0012]
As shown in FIG. 8, the vacuum breaker valve 29 </ b> A includes the valve body 1 and the flange plate 2 serving as a valve seat thereof, and the inside of the vent pipe 28 is negative with respect to the inside of the W / W 27. The valve body 1 is automatically opened by this negative pressure, thereby causing the D / W 26 to communicate with the W / W 27 and suppressing the pressure in the W / W 27 from becoming higher than the pressure in the D / W 26. .
[0013]
On the other hand, the vacuum break valve 29A is required to be checked for operation during a regular test. Therefore, as shown in FIG. 8, the valve body 1 and the flange plate 2, the arm 3 and the bearing 4 are further provided. A gas pressure cylinder 5, a piston 6, a test three-way solenoid valve 7, a test isolation solenoid valve 8, and a test nitrogen gas supply pipe 9.
[0014]
Therefore, the vacuum breaker valve 29A switches the open position of the test three-way solenoid valve 7 and supplies nitrogen gas to the gas pressure cylinder 5, whereby the piston 6 of the gas pressure cylinder 5 is pushed down in the direction of the broken arrow, The valve body 1 is moved in the direction of the broken arrow through the arm 3, so that it can be confirmed that the valve is forcibly opened and can be operated.
[0015]
FIG. 9 shows a test control logic for the vacuum breaker valve 29A, which is composed of a test switch and a control circuit as shown, and generates a vacuum breaker valve open signal by turning on the test switch during a regular operation test. Thus, an open test of the vacuum break valve can be performed. In the figure, E represents the energization of the solenoid valve.
[0016]
Furthermore, in this prior art, a condensate replenishment water system is provided as a system for sealing and cleaning pipes in nuclear power plants, and the water in the condensate storage tank 15 is also used in this system. At this time, as described in Japanese Patent Application Laid-Open No. 7-134194, the water in the condensate storage tank 15 is shared for normal use and emergency use.
[0017]
Therefore, in order to prevent the water in the condensate storage tank 15 from being used all the time, the drain pipe for the water source is used for condensate storage tank emergency (high pressure) for extracting water from the bottom of the condensate storage tank 15. The core cooling system) is installed separately into a lead-in pipe 20 and a condensate storage tank regular (condensate replenishing water system) lead-in pipe 21 that takes out water from the side.
[0018]
The condensate storage tank common / emergency communication pipe 18 and the condensate storage tank common / emergency communication pipe stop valves 49a and 49b are provided, and when necessary, the condensate storage tank is opened by opening the valves 49a and 49b. The water at the bottom of the condensate storage tank 15 is replenished from the emergency (high pressure core cooling system) lead-in pipe 20 to the condensate replenishment water system. As a result, the water at the bottom of the condensate storage tank 15 is also effective during periodic inspections of the plant. It can be used now.
[0019]
In addition, with this conventional technology, it is assumed that there is a severe accident in which these engineering safety facilities such as ECCS have multiple failures, even in this case, and even in this case, the current facilities can be used to the maximum, and further safety can be achieved. As a water injection facility, a condensate makeup water pump 16 and a condensate makeup water piping 17, a condensate storage tank regular (condensation makeup water system) lead-in piping 21, and a residual heat removal system communication valve 22 a are provided as water injection facilities. , 22b, and the condensate replenishment water system constituted by these and the condensate storage tank 15, the water in the condensate storage tank 15 is fed into the reactor pressure vessel 23 or the reactor containment vessel 25 via the residual heat removal system. It is designed to be able to inject water.
[0020]
Therefore, at the time of a severe accident, the condensate makeup water system can be used for cooling the reactor pressure vessel 23 as described below.
That is, at the time of a severe accident, first, water is poured into the reactor pressure vessel 23 so that the soundness of the reactor pressure vessel 23 is maintained. If there is no possibility, a large amount of water in the condensate storage tank 15 is poured into the reactor containment vessel 25 by the condensate makeup water pump 16, the reactor pressure vessel 23 is cooled from the outside, and this atomic The soundness of the furnace pressure vessel 23 is maintained.
[0021]
This is discussed in the next paper.
“In-vessel retention of corium at the Loviisa plant”
Nuclear Engineering and Design 169 (1997) 109-130
[0022]
[Problems to be solved by the invention]
In the above prior art, a large amount of water is supplied from the condensate storage tank to the D / W as a response to a severe accident such as a multiple failure of ECCS. At this time, a vacuum break valve exists in the vent pipe. Since water is also poured into the pressure suppression chamber, the amount of water necessary for cooling increases, and a rise in the water level in the D / W is delayed.
[0023]
This will be explained more specifically with reference to FIGS. 7 and 8. As described above, when the pressure in the vent pipe 28 becomes negative with respect to the W / W 27, the valve body 1 of the vacuum breaker valve 29 opens. As a result, D / W 26 and W / W 27 are communicated with each other and pressure is equalized.
[0024]
For this reason, even if the cooling water is supplied to the D / W 26, the supplied water is supplied from the D / W 26 to the vent pipe until the water level of the pool water in the pressure suppression chamber 30 rises and the vacuum breaker valve 29 is submerged. Since it will transfer to the pressure suppression chamber 30 via 28, a cooling water cannot be stored in D / W26 during this period.
[0025]
For this reason, in the prior art, after pouring water into the D / W 26, an extra amount of water is required until the water level in the D / W 26 necessary for cooling the reactor pressure vessel 23 from the outside is secured. The above problem occurs because it takes extra time.
In addition, the amount of water injection from the outside is limited in terms of the amount of water held in the plant, considering the water injection from the condensate makeup water system at the time of a severe accident.
[0026]
The purpose of the present invention is that the cooling water source can be used effectively, and even if a large amount of cooling water is injected into the reactor containment vessel and the reactor pressure vessel needs to be externally cooled, an extra amount of water is not required. An object of the present invention is to provide a reactor containment water injection system that can be supplied in a short time.
[0027]
[Means for Solving the Problems]
The above purpose is to irrigate the reactor containment vessel, which is divided into an upper space containing the reactor pressure vessel and a lower space serving as a pressure suppression chamber, and a vent pipe communicating with the upper space and the lower space is provided with a vacuum break valve. In the facility, the vacuum breaking valve is provided with a valve opening mechanism, and the valve opening mechanism is achieved by forcibly closing the vacuum breaking valve when water is poured into the upper space.
[0028]
At this time, the valve opening mechanism may include a gas pressure cylinder for preventing the vacuum breaker valve from operating due to a differential pressure between the upper space and the lower space and closing the valve.
[0029]
Similarly, at this time, the reactor containment vessel includes a condensate storage tank emergency lead-in pipe for the high-pressure core cooling system, a condensate storage tank regular lead-in pipe for the condensate makeup water system, and these condensate tank emergency lead-in pipes. And a condensate storage tank regular lead-in piping for the condensate make-up water system, and a motor-operated valve provided on the communication pipe, when the motor-operated valve is poured into the upper space, You may enable it to perform opening control .
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a reactor containment water injection system according to the present invention will be described in detail with reference to the illustrated embodiments.
FIG. 1 shows a first embodiment of the present invention. In this embodiment, as shown in FIG. 2, the configuration of the vacuum break valve 29 is the same as that of the vacuum break valve 29A in the prior art described in FIGS. The condensate storage tank common / emergency communication piping stop valves 49a, 49b in the prior art of FIG. 9 are simply replaced with the condensate storage tank regular / emergency communication piping electric stop valves 19a, 19b. Other configurations are the same as those of the prior art facility described in FIG.
[0031]
Therefore, also in the embodiment of FIG. 1, the condensate storage tank 15 and the condensate storage tank regular (condensate makeup water system) lead-in pipe 21, the condensate makeup water pump 16, the condensate makeup water pipe 17, and the residual heat removal system communication. The point that the condensate replenishment water system is configured by the valves 22a and 22b is the same as that of the prior art, and when a severe accident such as a multiple failure of ECCS occurs, water is taken in from the bottom of the condensate storage tank 15 and the reactor containment vessel 25 This is also the same as the point where water is poured into the D / W 26.
[0032]
Next, the operation of this embodiment will be described.
When a severe accident such as a multiple failure of the ECCS occurs, the condensate storage tank normal / emergency connection piping electric stop valves 19a and 19b are opened by remote operation by an operator from the central control room, and the condensate makeup water pump 16 is opened. Thus, water is taken out from the bottom of the condensate storage tank 15 and poured into the D / W 26 of the reactor containment vessel 25 through the residual heat removal system.
[0033]
Further, the vacuum break valve 29 is controlled to be kept closed simultaneously with the water injection operation of the D / W 26, whereby the D / W 26 and the W / W 27 are communicated with each other by the vacuum break valve 29, and the inside of the D / W 26 The cooling water poured into the pressure control chamber 30 is prevented from flowing into the pressure suppression chamber 30 through the vent pipe 28, and the poured cooling water is accumulated only in the D / W 26.
[0034]
Therefore, according to this embodiment, even if it is necessary to externally cool the reactor pressure vessel, there is no risk of water being poured into the excess portion, so that the amount of water can be reduced with a minimum amount of time and a minimum amount of time. / W26 can be filled with cooling water, and at this time, since water is taken out from the bottom of the condensate storage tank 15, the cooling water source can be used effectively, and the D / Water can be poured into W26.
[0035]
For this reason, the vacuum breaker valve 29 in the embodiment of FIG. 1 is configured as shown in FIG.
Here, first, a valve body 1, a flange plate 2, an arm 3, a bearing 4, a gas pressure cylinder 5, a piston 6, a test three-way solenoid valve 7, a test isolation solenoid valve 8, and a test nitrogen gas supply pipe 9 are provided. This is the same as the vacuum break valve 29A in the prior art described with reference to FIG.
[0036]
However, in the vacuum breaker valve 29 in this embodiment, the fluid pressure actuator comprising the gas pressure cylinder 5 and the piston 6 is a double-acting type, and further, the nitrogen gas supply pipe 10 for forcibly closing the vacuum breaker valve and the three-way electromagnetic for closing. The valve 11, the isolation solenoid valve 12 for closing and closing, the accumulator 13 for storing closing nitrogen gas, and the check valve 14 for storing accumulator nitrogen gas are different from the conventional vacuum breaking valve 29A.
[0037]
Accordingly, by switching the opening direction of the closing three-way solenoid valve 11 and supplying the nitrogen gas stored in the accumulator 13, the piston 6 of the gas pressure cylinder 5 is pushed up as shown by the solid line arrow. Even if the pressure P2 on the W / W27 side in the reactor containment vessel 25 exceeds the pressure P1 on the D / W26 side, the vacuum breaker valve 29 can be forcibly closed so as not to open. It has become.
[0038]
Here, the vacuum breaker valve 29 in this embodiment also switches the opening direction of the test three-way solenoid valve 7 to supply nitrogen gas when the regular operation test is performed, and the gas pressure cylinder 5 as shown by the broken line arrow. The piston 6 in the gas pressure cylinder 5 is free to move up and down because the opening direction of the three-way solenoid valves 7 and 11 is normally switched to the atmosphere. Therefore, the basic vacuum breaking function is not impaired.
[0039]
Next, the control logic (signal circuit) of the condensate storage tank common / emergency connection piping electric stop valves 19a, 19b and the vacuum breaker valve 29 according to this embodiment will be described with reference to FIG.
The control logic of FIG. 3 is composed of switches, relays, relay contacts, and the like. The upper side is the control logic of the electric stop valves 19a and 19b, and the lower side is the control logic of the vacuum breaker valve 29.
Since the electric stop valve 19a and the electric stop valve 19b are the same control logic, only one control logic of the electric stop valves 19a and 19b is shown on the upper side of FIG.
[0040]
First, the condensate storage tank normal / emergency communication piping electric stop valves 19a and 19b are controlled by a condensate storage tank normal / emergency communication piping electric stop valve switch operated by an operator as shown in the figure.
However, at this time, the cooling water in the condensate storage tank 15 is prioritized to be used as the ECCS water source, and thus a function for guaranteeing this is necessary. For this reason, an ECCS activation signal is generated. Is configured to prohibit the open control of the condensate storage tank common / emergency communication piping electric stop valve.
[0041]
That is, the output signal for opening the condensate storage tank normal / emergency connection piping electric stop valve is an ECCS start signal, and at this time, the ECCS start signal forced switch is in the normal position. , And is configured to be supplied to the subsequent stage. In FIG. 3, WO (wipeout) represents logic (prohibition logic) in which transmission of a signal from the left to the right is prohibited when there is an input from above.
[0042]
Therefore, when the ECCS activation signal is generated, the condensate storage tank emergency / emergency connection piping electric stop valve cannot be opened. However, in the event of a severe accident, water is injected into the reactor containment vessel. Since the ECCS activation signal may be generated in a necessary state, in this case, the ECCS activation signal is forced so that the ECCS activation signal can be forcibly cut off at the operator's discretion. Is provided with a switch for shutting off.
[0043]
In addition, as shown in the figure, the condensate storage tank emergency / emergency connection piping electric stop valve is controlled by self-holding logic by feeding back the output of the WO logic to the input, so that this self-holding state is released. The valve fully open input and the valve fully close input are provided.
[0044]
Next, the vacuum breaker valve 29 is controlled by a vacuum breaker valve forced open switch operated by an operator as shown in the figure.
However, if a differential pressure is generated at D / W 26 and W / W 27 at this time, the original function of the vacuum breaker valve that equalizes these pressures is given priority. As a function for guaranteeing, the signal output from the vacuum breaker valve forcibly closing switch is configured to be transmitted to the subsequent stage on condition that the ECCS activation signal from the signal from (1) is not output. At the same time, the output from the vacuum breaker valve test switch is configured to be shut off by WO.
[0045]
Next, FIG. 4 shows another embodiment of the control logic of the condensate storage tank normal / emergency connection piping electric stop valves 19a and 19b and the vacuum breaker valve 29. In the embodiment of FIG. The prohibition logic by the ECCS activation signal for the output signal of the closed switch is changed from the AND circuit to the WO logic, and the other configurations are the same.
[0046]
Note that the control logic described in FIGS. 3 and 4 is not limited to the hard-wired / relay circuit, and may be configured by an electronic circuit using an integrated circuit (IC) chip.
[0047]
Next, FIG. 5 shows another embodiment of the present invention, which is different from the embodiment described in FIG. 1 in that a high-pressure nitrogen cylinder 50 is installed instead of the accumulator 13 in the embodiment of FIG. Nitrogen gas is supplied to the pressure cylinder 5. Air may be used instead of nitrogen.
[0048]
Therefore, according to the embodiment of the present invention, since the vacuum breaker valve 29 provided in the vent pipe 28 can be forcibly maintained in the closed state, the pool water level in the pressure suppression chamber 30 is increased, It is possible to forcibly create the same state as the vacuum break valve is submerged.
[0049]
For this reason, when water is poured into the D / W 26, it is possible to prevent the water from flowing into the pressure suppression chamber 30, and the poured cooling water can be concentrated on the D / W side from the beginning. The water injection time required to submerge the 29 is unnecessary, and the delay caused by the rise of the water level in the D / W can be reduced accordingly. As a result, it is sufficient for a severe accident such as multiple ECCS failures in a short time. It can respond and can easily maintain high reliability.
[0050]
Further, since the cooling water can be prevented from flowing into the pressure suppression chamber 30, the amount of water necessary for cooling the reactor pressure vessel 23 can be reduced by that much, and it is sufficiently prepared for a situation where the cooling water is insufficient. In this respect, high reliability can be easily obtained.
[0051]
Further, in the event of a severe accident, the condensate storage tank regular / emergency connection piping electric stop valves 19a and 19b are opened to take out water from the bottom of the condensate storage tank 15, Almost all of the water can be poured into the reactor containment vessel 25, and sufficient safety can be ensured by effective utilization of the water retained in the plant.
[0052]
【The invention's effect】
According to the present invention, since a sufficient amount of cooling water can be poured into the reactor containment vessel without requiring an excessive amount of water in a short time, the cooling water source can be effectively used. Even when a large amount of cooling water is poured into the vessel and the reactor pressure vessel needs to be externally cooled, sufficient countermeasures can be taken.
[0053]
Therefore, according to the present invention, severe accidents such as multiple failures of ECCS can be sufficiently handled in a short time, and high reliability can be easily maintained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a reactor containment water injection system according to the present invention.
FIG. 2 is a detailed explanatory view showing an example of a vacuum break valve in one embodiment of the present invention.
FIG. 3 is an explanatory diagram illustrating an example of control logic according to an embodiment of the present invention.
FIG. 4 is an explanatory diagram showing another example of the control logic in one embodiment of the present invention.
FIG. 5 is a block diagram showing another embodiment of a reactor containment water injection system according to the present invention.
FIG. 6 is a detailed explanatory view showing an example of a vacuum break valve according to another embodiment of the present invention.
FIG. 7 is a block diagram showing an example of a reactor containment water injection facility according to the prior art.
FIG. 8 is a detailed explanatory diagram of a vacuum breaker valve in an example of the prior art.
FIG. 9 is an explanatory diagram of control logic in an example of the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Valve body 2 Flange plate 3 Arm 4 Bearing 5 Gas pressure cylinder 6 Piston 7 Three-way solenoid valve for test 8 Isolation solenoid valve for test 9 Nitrogen gas supply pipe for test 10 Nitrogen gas supply pipe for vacuum closing valve forced closing 11 Vacuum break Three-way solenoid valve 12 for forced shut-off of valve Isolation solenoid valve 13 for forced shut-off of vacuum break valve Accumulator 14 for forced shut-off of vacuum break valve Accumulator for forcible shut-off of vacuum break valve Nitrogen gas storage check valve 15 Condensate storage tank 16 Condensate replenishment water Pump 17 Condensate replenishment water pipe 18 Condensate storage tank regular / emergency communication pipe 19 Condensate storage tank regular / emergency communication pipe Electric stop valve 20 Condensate storage tank emergency (high pressure core cooling system) lead-in pipe 21 Condensate Storage tank regular (condensate makeup water system) lead-in pipe 22 Residual heat removal system communication valve 23 Reactor pressure vessel 24 Core 25 Reactor containment vessel 26 Raiweru (D / W)
27 Wet Well (W / W)
28 Vent pipe 29 Vacuum break valve 30 Pressure suppression chamber 31 Strainer 32 High pressure core cooling pump 33 High pressure core cooling pump suction valve 34 High pressure core cooling water injection valve 35 High pressure core cooling piping 36 Main steam piping 37 Main steam relief safety valve 38 Residual heat removal pump 39 Residual heat removal pump suction valve 40 Low pressure core water injection valve 41 Residual heat removal piping 42 Heat exchanger 43 Heat exchanger switching valve 44 Auxiliary equipment cooling pump 45 Dry well spray valve 46 Dry well spray header 47 Wet well spray valve 48 Wet wells Play header 49 Condensate storage tank regular / emergency connection stop valve 50 High pressure nitrogen cylinder

Claims (3)

In the water injection facility for the reactor containment vessel, which is divided into an upper space containing the reactor pressure vessel and a lower space serving as a pressure suppression chamber, and a vent pipe communicating with the upper space and the lower space is provided with a vacuum break valve.
A valve opening mechanism is provided in the vacuum breaker valve,
The reactor opening water injection equipment, wherein the valve opening mechanism is configured to forcibly close the vacuum break valve when water is injected into the upper space. In the invention of claim 1,
The valve opening mechanism includes a gas pressure cylinder for preventing the operation of the vacuum breaker valve due to a pressure difference between the upper space and the lower space and closing the valve. . In the invention of claim 1 ,
The reactor containment vessel,
Condensate storage tank emergency lead-in piping for high-pressure core cooling system, condensate replenishment water system condensate storage tank regular lead-in piping, and condensate storage tank emergency lead-in piping and condensate replenishment water system condensate storage tank regular pull-in A communication pipe that communicates between the pipes, and a motor-operated valve provided on the communication pipe,
Reactor containment vessel water injection equipment, wherein the motor-operated valve is configured to be capable of opening control when water is injected into the upper space.

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