JPH0631796B2 - Reactor water purification device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a BWR reactor water purification system, and more particularly to a reactor water purification system capable of effectively purifying reactor water during operation and shutdown of a plant. .

[Background of the Invention]

Fig. 4 shows a conventional BWR reactor water purification system. The functions of the reactor water purification system are as follows:
Purification function of reactor water to maintain the water quality of reactor water within the standard value at shutdown, and increase due to thermal expansion of reactor water at reactor startup, reactor by injection of cold water from control rod drive hydraulic system It is a function to control the reactor water level to a predetermined level by discharging the increased water.

In FIG. 4, the reactor water in the reactor pressure vessel 1 is taken out from the suction line of the reactor recirculation pump 2 and the bottom of the reactor pressure vessel 1 by taking-out lines 3 and 4, respectively, and the lines join and store. Pump 5 through container isolation valves 5 and 6
1 is pressurized, is cooled to a predetermined temperature (about 50 ° C.) by the regenerative heat exchanger 52 and the non-regenerative heat exchanger 53, is purified by the super-desalination unit 54, and the purified reactor water is regenerated by the heat of regeneration. Exchanger 5
It is heated at 2 and returned to the reactor through the water supply line 34.
The cooling in the non-regenerated heat exchanger 53 is performed by supplying the cooling water cooled by the cooling source 15 with the pump 16.

During normal operation of the reactor, the reactor water is purified by the circulation cycle as described above, but the increased amount of the reactor water is discharged at the time of starting the reactor after passing through the super-desalination unit 54 and then the condenser. Waste receiving tank of the waste treatment system by blowing into the condenser through line 56 to the condenser, and through line 57 to the waste receiving tank when bypassing the desalting device 54 through the bypass line 55. It is carried out by discharging to 57.

By the way, in order to simplify the equipment of a BWR plant, there is a well-known example in which a condensate demineralizer of a turbine system is used instead of the conventional single reactor water purifier as described above to purify the reactor water. It is disclosed in Japanese Laid-Open Patent Publication No. 54-36477. This is to cool the reactor water by connecting the downstream side of the heat exchanger of the residual heat removal system of the reactor and the upstream side of the condensate demineralizer of the turbine system, and passing reactor water through the reactor at low pressure and during shutdown. Purification is performed to remove clads in reactor water and reduce radioactivity. Normally, when the reactor is shut down, the reactor residual heat removal system cools and depressurizes the reactor, but in the above-mentioned known example, after the reactor internal pressure has sufficiently decreased, reactor water is removed from the reactor residual heat removal system heat exchanger. After being cooled in step 1, it is passed through a turbine-based condensate demineralizer and then returned to the reactor through the water supply system. Here, it is necessary to pass the reactor water to the condensate demineralizer after the reactor pressure has sufficiently decreased (that is, after the reactor water temperature has sufficiently decreased) because the condensate demineralizer inlet line is at the normal temperature. Is about 40 ° C. and the pressure is about 6 to 8 kg / cm ² in the normal operation state of the reactor, so it is necessary to sufficiently reduce the pressure and decrease the temperature.

Therefore, in the above-mentioned known example, the reactor water cannot be purified at high pressure and high temperature of the reactor. In addition, the reactor residual heat removal system is in a standby state as one of the emergency core cooling systems during the operation of the reactor and cannot be used at all times.
As described above, the above-mentioned known example is limited in its use range only when the reactor pressure is low and when the reactor is shut down. Further, when the water supply system cannot be used during the plant periodic inspection during the reactor shutdown, for example, when the water supply system heater and pump are inspected or repaired, the reactor water cannot be purified.

As mentioned above, it is to rationalize the plant equipment, to add the function of the reactor purification device to the turbine system condensate demineralizer.
Although desirable in terms of simplification, the conventional proposals have not been satisfactory in terms of usage conditions and usage range.

[Object of the Invention]

An object of the present invention is to provide a reactor water purification system that shares a rational and effective reactor water purification function while maintaining the original function of the existing facilities by sharing the existing BWR facilities. is there.

[Outline of Invention]

In order to achieve the above object, the reactor water purification according to the present invention effectively reduces the pressure of reactor water taken out from the reactor by the pressure reducing means in order to purify the reactor water at high pressure and high temperature during normal operation. Further, the reactor water whose temperature has been reduced by the cooling means is passed through an over-desalination apparatus to be purified and then heated and returned to the reactor again. In this case, the purification function of the over-desalination apparatus is performed. All or a part of the above was carried out by a condensate system over desalting apparatus.

Condensate of a system to be purified is used as the cooling means, and a flash tank is used as the depressurizing means.
The flash steam generated when the high-pressure reactor water is depressurized is absorbed by the steam line in the plant for recovery, and combined with the use of condensate in the system to be purified, the release of thermal energy outside the plant is suppressed. There is.

Bypassing the water heater, pumps, etc. so that the reactor water can be purified even when the reactor water supply is stopped during plant outages during plant shutdowns, etc., so that purified reactor water can be returned to the reactor is doing.

Example of Invention

An embodiment of the present invention will be described with reference to FIG. The reactor water purification line is the same as that of the conventional reactor water purification system up to the passage of the reactor water withdrawal lines 3 and 4 and the containment vessel isolation valves 5 and 6 from the reactor pressure vessel 1. After passing through the flow control valve 7, the flash tank 8 is once depressurized to a predetermined pressure, and the depressurized reactor water is cooled to a predetermined temperature (about 50 ° C.) by the heat exchanger 9, and then the filter 1
0 through which the reactor water passes, the pump 11 or its bypass line 12, and the upstream side of the condensate demineralizer 28.

Explaining the configuration around the turbine, the steam generated from the reactor pressure vessel 1 is guided to the high-pressure turbine 22 by the main steam line 21, and the steam leaving the high-pressure turbine 21 is separated by the moisture separator 23 into moisture. It is removed and guided to the low pressure turbine 24 where it is rotated. The steam that has exited the low-pressure turbine is cooled and condensed in the condenser 25, and the condensed condensate is pressurized by the low-pressure condensate pump 26, and the condensate separator 27,
It is over-desalted through the condensate demineralizer 28, then pressurized by the high-pressure condensate pump 29, warmed by the low-pressure heaters 30 and 31, further boosted by the water supply pump 32, and heated by the high-pressure heater 33. , And is sent to the reactor through the water supply line 34. The high-pressure heater 33 is heated by extraction steam from the extraction line 42 of the high-pressure turbine, and the low-pressure heaters 30 and 31 are heated by extraction steam from the low-pressure turbine or the like.

Cooling of the heat exchanger 9 is performed by introducing cooling water from the outlet line of the low pressure condensate pump 29 through a cooling water line 37.
After cooling the heat exchanger 9, the low-pressure heater 3 is supplied through the line 38.
It is designed to be returned to the exit side of 0. Further, the cooling of the heat exchanger 9 is also performed by a cooling source 15 independent from the above.

The flash steam generated by the decompression in the flash tank 8 passes through the flash steam line 13 and the high pressure turbine 2
The pressure can be recovered in the second outlet line, and the flash steam line 13 is provided with a pressure control valve 13 'so that the pressure in the flash tank 8 can be controlled. The flash steam line is connected to the condenser 25 via the pressure control valve 14.
I can blow it.

Further, a water supply system bypass line 36, which is branched from the outlet of the condensate demineralizer 28 and is directly connected to the water supply line 34, is provided. Condensate that has left the condensate demineralizer 28
If necessary, it can be blown to the condenser 25 through a line 35 to the condenser 25.

The above is the overall configuration of the embodiment. Next, the operation mode of each mode will be described for the normal reactor operation, the reactor startup, and the reactor shutdown.

Since the reactor is in a high temperature and high pressure state during normal operation of the reactor, the reactor water passed through the condensate demineralizer 28 has a temperature of 40 to
It is necessary to reduce the temperature to about 60 ° C and the pressure to about 6 to 8 kg / cm ² and reduce the pressure. Therefore, the reactor water taken out of the nuclear reactor 1 is first depressurized in the flash tank 8 to a predetermined pressure. When the pressure is reduced, part of the reactor water is flushed to generate steam, and this flash steam is released from above the flash tank 8 to the main steam line at the outlet of the high-pressure turbine 22. The pressure of the main steam line at the outlet of the high-pressure turbine 22 is about 14 kg / cm ² , and therefore the pressure in the flash tank 8 is also about the same.

The reactor water decompressed in the flash tank 8 and cooled accordingly is cooled in the heat exchanger 9 to a predetermined temperature (about 50 ° C.). Condensate introduced from the outlet of the high-pressure condensate pump 29 is used as cooling water for the heat exchanger 9. The outlet temperature of the heat exchanger 9 of the reactor water is monitored by the temperature detector 41, and the outlet temperature can be controlled by operating the valve 40 on the cooling water side based on the output signal and adjusting the cooling water amount. ing.

Thus, the reactor water cooled to a predetermined temperature (about 50 ° C.) is filtered by the filter 10 and guided to the condensate demineralizer 28 through the bypass line 12 of the pump 11. Since the reactor pressure is high during normal operation of the reactor, it is not necessary to pressurize the reactor water with the pump 11, and the bypass line 12
It can be introduced into the condensate demineralizer 28 by passing it through. The reactor water guided to the condensate demineralizer 28 is purified by the condensate demineralizer 28 and returned to the reactor through the condensate system and the water supply system.

It may be feared that the radiation dose may be increased by guiding the reactor water to the condensate desalination device 28, but the reactor water is sufficiently cooled by the heat exchanger 9, and the radiation dose is in a reduced state. Since the filter 10 is used, there is no particular problem regarding the radiation dose.

Since the reactor is at low pressure when the reactor is started, pump 1
The reactor water is guided to the condensate demineralizer 28 by pressurizing with 1. The increase in the reactor water at the time of starting the reactor is blown from the outlet line of the condensate demineralizer 28 through the line 35 to the condenser 25.

The operation after the next reactor shutdown will be described. When the reactor water supply system is in a stopped state due to a regular inspection or the like, the reactor water pressurized by the pump 11 is passed through the condensate demineralizer 28 and then returned to the reactor through the water supply system bypass line 36. . Further, when the reactor is stopped as in the high temperature standby state but the feed water system is bypassed while the reactor is in a high temperature state, the heat exchanger 9 cannot be cooled by condensate. The heat exchanger 9 is cooled by an independent cooling source 15. Also in this case, the reactor water temperature at the outlet of the heat exchanger 9 can be controlled by operating the valve 39 in the return line to the cooling source 15 based on the signal from the temperature detector 41.

Another embodiment of the present invention is shown in FIGS.

The difference from FIG. 1 of FIG. 2 is that the flash steam from the flash tank 8 is released not to the outlet line of the high-pressure turbine 22 but to the extraction line of the turbine 22. Such an embodiment is also possible because it is a steam line under the same pressure conditions.

The difference from FIG. 1 of FIG. 3 is that the reactor water is introduced upstream of the condensing device 27 without providing the filter 10 in the reactor water side outlet line of the heat exchanger 9. That is the point. With such a configuration, the same function as that of the embodiment shown in FIG. 1 can be achieved.

[Effect of Example]

According to the embodiment of the present invention described above, the heat exchanger is cooled by the condensate of the condensate system, so that the release of heat energy to the outside of the plant is suppressed and the thermal efficiency is improved.

Since the conventional reactor water purification system as shown in FIG. 4 can be deleted, the system can be simplified.

Further, although the pump 51 of the conventional reactor water purification system is installed in a high pressure and high temperature state, as shown in FIG. 1, in the example of the present invention, the pump 51 is installed on the low temperature side downstream of the heat exchanger 9. The radiation dose rate can be reduced, pump reliability can be improved, maintenance and checkability can be improved.

〔The invention's effect〕

According to the present invention, the function of the conventional BWR conventional desalination system of the reactor water purification system can be replaced by the function of the condensate deionization system of the turbine system. In addition to what can be done, one pump 51 can be reduced and the regenerative heat exchanger 52 can be removed during normal operation of the nuclear reactor and during high temperature standby, and the overall configuration can be simplified and rationalized.

In addition, since a line that bypasses the feed water heater and the pump of the feed water system, etc., is provided, during the reactor shutdown, the feed water line including the high pressure condensate pump is in the stopped state, , By bypassing the equipment of the water supply line, the reactor water can be purified and injected into the reactor, and during operation of the reactor, the pump connected to the heat exchanger and the parallel circuit of the bypass line Reactor water can be fed upstream of the desalination device through a bypass line to stop the pumps in the parallel circuit.

Further, by cooling the heat exchanger 9 with the condensate system, it is possible to rationalize the entire plant such as reducing heat loss in the plant and improving output at the power generation end.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of an embodiment of the present invention, and FIGS. 2 and 3 are configuration diagrams of other embodiments of the present invention. FIG. 4 shows a block diagram of a conventional reactor cleaning system. 8 ... Flash tank, 9 ... Heat exchanger 11 ... Pump, 27 ... Condensate passing device 28 ... Condensate demineralizer, 30 ... Low-pressure heater 36 ... Water supply system bypass line 37, 38 ... Cooling water line 51 ... Pump, 52 … Regenerated heat exchanger 53… Non-regenerated heat exchanger, 54… Filtration demineralizer

Claims (1)

[Claims] 1. A reactor water removal line from the bottom of a nuclear reactor,
A parallel circuit consisting of a pressure reducing means, a heat exchanger, a filter, a pump and a bypass line is sequentially connected in series, while a turbine and a condenser are connected to the main steam line from the reactor, and the condensate from the condenser is connected. Is connected through a low pressure condensate pump, a condensate vaporizer, a condensate demineralizer, a high pressure condensate pump, and a heater in order to return to the reactor, and at least the outlet side of the parallel circuit is condensate dewatered. A reactor water purification apparatus, which is connected to an upstream side of a salt system, and a feed water bypass line is connected in parallel to the high-pressure condensate pump and the heater.