JPH0441359Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a grand seal device for a cooling system during nuclear reactor isolation.

[Conventional technology]

In a boiling water nuclear power plant, the steam generated in the reactor is sent to the main turbine to generate electricity, and the steam exiting the main turbine is condensed and returned to the reactor via the water supply system. If this circulation is interrupted for some reason and the reactor is isolated, the reactor pressure increases and the safety relief valve operates to keep the reactor pressure within a set value. On the other hand, since the feed water is being lost, the reactor water level will continue to fall as steam generation from decay heat continues.

In such a case, a reactor isolation cooling system is provided to cool the core and maintain the reactor water level. That is, when the reactor water level becomes low, a turbine pump is driven by reactor steam, and water in the condensate storage tank is injected into the reactor.

Furnace steam tends to flow out from the ground leak part of the turbine, so a gland sealing device is required to prevent this from leaking out of the system.
The configuration of a conventional reactor isolation cooling system grand seal device will be explained with reference to FIG.

In FIG. 4, during reactor isolation, a turbine pump 2 is driven by reactor steam generated within the reactor 1, and water from a condensate storage tank 3 is injected into the reactor 1. After driving the turbine pump 2, the steam is discharged through a steam drainage pipe 2a into a suppression chamber 4 storing cooling water 4a. on the other hand,
Steam attempting to flow out from the turbine gland leak portion of the turbine pump 2 is led to a barometric condenser 6 via a gland leak pipe 5, where it is condensed and stored in a vacuum tank 7.
In order to maintain the degree of vacuum in the vacuum tank 7 and always draw steam from the turbine gland leak part of the turbine pump 2, the non-condensable gas accumulated in the vacuum tank 7 is removed by the vacuum pump 8 through the gland seal piping 8a.
cooling water 4 in the suppression chamber 4 through
Discharge into a. Further, when the water level in the vacuum tank 7 rises, the condensate pump 9 is activated to discharge condensed water to the suction side of the turbine pump 2.

There is a vacuum breaker valve 10 on the suction side of the vacuum pump 8, and when the pressure inside the vacuum tank 7 is low, the vacuum pump 8
When there is a risk of insufficient suction pressure, air is sucked in from outside the system. Further, a separator 11 is provided in the grand seal piping 8a on the discharge side of the vacuum pump 8 to remove moisture from the exhaust gas, and the moisture separated by the separator 11 is returned to the vacuum tank 7 via the return piping 11a. I am beginning to be guided within. This separator 11
A bypass line 13 is disposed in the downstream gland seal piping 8a in order to guide the non-condensable gas back into the vacuum tank 7 for circulation operation when it becomes impossible to exhaust the gas into the suppression chamber 4. A pressure regulating valve 12 is provided in this bypass line 13 to regulate the pressure inside the pipe.

[Problem that the invention attempts to solve]

In the above configuration, even in the event of a loss of coolant accident in which reactor water flows out of the reactor due to a rupture in a pipe, the reactor isolation cooling system is activated due to the low reactor water level. However, unlike during reactor isolation, the pressure within the suppression chamber 4 increases during an accident, and this pressure may exceed the maximum discharge pressure of the vacuum pump 8. As a result, the vacuum pump 8 is operated in a closed loop with the vacuum tank 7,
The degree of vacuum in the vacuum tank 7 cannot be maintained, and furnace steam leaks out of the system from the turbine gland leak portion of the turbine pump 2.

Furthermore, even if the pressure rise in the suppression chamber 4 is small, the suction of air from the vacuum breaker valve 10 will increase the oxygen concentration in the suppression chamber 4, increasing the possibility of a hydrogen explosion. Become.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a reactor isolation cooling system gland seal device that can maintain its function even in the event of a loss of coolant accident and does not bring oxygen into the suppression chamber. With the goal.

[Means for solving problems]

This invention consists of a barometric condenser and a vacuum tank that suck and condense leaked steam from the turbine gland leak part in the reactor isolation cooling system that replenishes cooling water to the reactor using a turbine pump driven by reactor steam. In a reactor isolation cooling system ground sealing device that has a vacuum pump that maintains the vacuum level of the vacuum tank, the maximum discharge pressure of the vacuum pump is set to the maximum pressure of the suppression chamber or higher, and from the discharge side of the vacuum pump A cooling system grand seal device for reactor isolation is characterized in that a bypass line returning to a vacuum tank is provided, and this bypass line is provided with an orifice and a pressure regulating valve to adjust the flow rate.

[Effect]

In a device configured in this way, if the pressure inside the suppression chamber increases during a coolant loss accident, the vacuum pump is shut down by throttling the pressure regulating valve installed in the bypass line or by completely closing it. It is possible to operate at a discharge pressure higher than the pressure in the suppression chamber, and the degree of vacuum in the vacuum tank can be maintained.

In cases other than the above, it is possible to maintain the degree of vacuum in the vacuum tank by fully opening or throttling the pressure regulating valve installed in the bypass line to cope with the increase in flow rate due to the decrease in the discharge pressure of the vacuum pump. can.

〔Example〕

Hereinafter, a first embodiment of the present invention will be described with reference to FIG. Here, FIG. 1 shows a schematic configuration diagram of a cooling system grand seal device during reactor isolation. Note that the first
In the figure, the same parts as in FIG. 4 are given the same reference numerals, and the explanation of the structure of the parts will be omitted. In FIG. 1, a bypass line 13 returning to the vacuum tank 7 is provided in the gland seal piping 8a on the downstream side of the separator 11. The bypass line 13 includes a pressure regulating valve 15 that controls the downstream pressure at a constant level, and an orifice 14 that restricts the flow rate so that an excessive flow rate does not flow into the bypass line 13.
is provided. In addition, the gland seal piping 8
The vacuum pump 18 installed in a is set so that the maximum discharge pressure exceeds the maximum pressure set in the suppression chamber 4, and is used to prevent the conventionally provided vacuum breaker valve 10 and vacuum pump 8 from shutting down. The pressure regulating valve has been removed.

In the above configuration, if the pressure inside the suppression chamber 4 increases when coolant is lost,
In order to keep the pressure in the vacuum tank 7 constant, the pressure regulating valve 15 is throttled down and the flow rate in the bypass line 13 is suppressed. As a result, the flow rate of the vacuum pump 18 is suppressed, and the vacuum pump 18 can be operated at a discharge pressure higher than the pressure inside the suppression chamber 4. Since the flow rate of the bypass line 13 is continuously adjusted according to the discharge pressure of the vacuum pump 18, there is no need to provide a vacuum breaker valve to allow air to be sucked. At this time, the flow rate is restricted by the orifice 14 so that an excessive flow rate does not flow into the bypass line 13.

As described above, it is possible to maintain its function even in the event of a loss of coolant accident, and the suppression chamber 4
It is possible to obtain a cooling system grand seal device for reactor isolation that does not introduce oxygen into the reactor.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 2, the same parts as in FIG. 1 are designated by the same reference numerals, and the explanation of the structure of the parts will be omitted. In FIG. 2, the bypass line 16 has one end open to the gas phase portion of the suppression chamber 4. As shown in FIG. With the above configuration, the vacuum pump 1
When the discharge pressure of 8 is low and the flow rate is larger than the inflow from the turbine pump 2 to the vacuum tank 7, air is sucked in from the suppression chamber 4 to prevent the pressure in the vacuum tank 7 from becoming excessively low. . As a result, the same effects as the first embodiment of the present invention can be obtained.

Further, a third embodiment of the present invention will be described with reference to FIG. As shown in FIG. 3, a pressure gauge 17 is provided in the vacuum tank 7, and a pressure signal 17a is sent from the pressure gauge 17 to the pressure regulating valve 15 to adjust the opening degree of the pressure regulating valve 15. According to the above configuration, it is possible to obtain the same functions and effects as in the first embodiment of the present invention.

[Effect of idea]

As described above, the reactor isolation cooling system gland seal device according to the present invention includes a bypass line connecting the downstream side of the separator and the vacuum tank, a pressure regulating valve and an orifice in this bypass line, and a vacuum pump discharge valve. Since the pressure is set higher than the maximum pressure set in the suppression chamber, its function can be maintained even in the event of a loss of coolant accident, and leakage of furnace steam to the outside of the system can be prevented. Furthermore,
Since oxygen can be prevented from being brought into the suppression chamber in the event of an accident, the possibility of hydrogen explosion can be reduced.

[Brief explanation of the drawing]

1 to 3 are schematic configuration diagrams of reactor isolation cooling system grand seal devices according to the first to third embodiments of the present invention, respectively, and FIG. 4 is a reactor isolation cooling system grand seal device FIG. 2 is a configuration diagram showing a conventional example. 1...Turbine pump, 2...Suppression chamber, 6...Barometric condenser, 7
... Vacuum tank, 13, 16 ... Bypass line, 14 ... Orifice, 15 ... Pressure regulating valve,
17...Pressure gauge, 18...Vacuum pump.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A barometric condenser and vacuum tank that sucks and condenses leaked steam from the turbine gland leak part in a turbine pump that constitutes the reactor isolation cooling system, and the vacuum of this vacuum tank. In a reactor isolation cooling system grand seal device consisting of a vacuum pump that maintains the maximum discharge pressure of the vacuum pump and guides leaked steam to the suppression chamber via the gland seal piping, the maximum discharge pressure of the vacuum pump is set to the suppression chain. A bypass line is installed that leads from the downstream side of the vacuum pump to the vacuum tank, and there is a pressure regulating valve in this bypass line that controls the downstream pressure at a constant level, and an excessive flow rate in the bypass line. 1. A cooling system grand seal device for reactor isolation, characterized by comprising an orifice for restricting the flow of nuclear reactor isolation cooling system. (2) The reactor isolation cooling system grand seal device according to claim 1, wherein the bypass line is led from the grand seal piping on the downstream side of the vacuum pump. (3) The atom according to claim 1, wherein the bypass line is led from a gas phase part of a suppression chamber in which one end of the gland seal piping is open. Cooling system gland seal device during furnace isolation. (4) The reactor isolation system according to any one of claims 1 to 3 of the utility model registration claim, wherein the pressure regulating valve is controlled by a pressure signal from a vacuum tank. Cooling system gland seal device.