JPH0756368B2 - Steam generator plant - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to steam generator plants.

[Background of the Invention]

In a high-speed plant after the demonstration reactor (which is between the experimental reactor and the practical reactor), a method of removing decay heat after the reactor trip using a normal cooling system facility is being studied. In order to streamline the equipment as the type of steam generator after the demonstration reactor,
It is expected that an integrated flow-through type will be adopted instead of the two separate units of evaporator and superheater used in the fast prototype reactor "Monjiyu."

However, for the purpose of relaxing the thermal transient (temporal change of heat) conditions on the cooling system equipment during the reactor trip and facilitating restart after the reactor trip, the high temperature standby assumed in the plant operation cycle There is a demand for a cooling system plant that enables the mode. Therefore, it is desired to develop a rational reactor steam system that satisfies the two requirements of being able to operate in the high-temperature standby mode as an integrated flow-through type.
As a conventional technique, a drain heat exchange system, a recirculation system, and a system in which a steam condenser is installed are known from experience of a thermal power boiler.

FIG. 6 is a piping diagram in which a conventional steam generator plant recirculation system is applied to a fast reactor plant. In the figure, 1 is a steam generator, 2 is an evaporation pipe, 3 is a steam separator, 4 is a turbine, 5 is a condenser, 6 is a deaerator, 7 is a feed pump, 8 is a feed water heater, and 9 is A recirculation pump, 10 is a pressure gauge, 11 is a pressure adjusting valve, 12 and 13 are steam flow path switching valves, and 14 is a water supply flow path switching valve. Further, 15 is a recirculation flow path switching valve, 16, 1
7,18 are steam flow paths, 19,20,21,22 are water supply flow paths, 23 are recirculation flow paths, 24 is a secondary sodium-based hot leg, 25 is a secondary sodium cold leg, and 26 is secondary sodium. It is a pump.

When the reactor trips, the primary sodium pumps and secondary sodium pumps stop, the operation shifts to pony motor operation, and the secondary sodium flow rate is secured at 6% of the rated state. The temperature of the secondary sodium flowing into the shell of the steam generator 1 from the secondary sodium-based hot-leg 24 does not decrease even when the reactor is tripped, so the temperature of the high temperature plenum in the reactor vessel does not decrease. Hardly changes. On the other hand, on the steam system side, in accordance with the load reduction on the secondary sodium side, the feed water pump 7 is sent by the reactor trip signal.
Reduce the number of rotations and reduce the water supply flow rate to 20 to 30% of the rated state.

The water flowing in the steam pipe 2 exchanges heat with secondary sodium, but the amount of heat exchanged is reduced, so unlike the heating steam at the time of rating, the steam separator 2 is a saturated steam in a two-phase state of water / steam. Head to. The steam and water are separated by the steam separator 3. First, the steam passes through the steam flow path 17 and the turbine 4
However, when the switching valve 12 is closed and the switching valve 13 is opened, the bypass steam passage 18 directly flows into the condenser 5 without passing through the turbine 4. The water condensed in the condenser 5
After the dissolved gas is further removed by the deaerator 6, the pressure is raised by the feed water pump 7 and further heated by the steam (not shown) by the feed water heater 8. On the other hand, the water in the steam separator 3 merges with the feed water from the feed water heater 8 because the switching valve 15 provided in the recirculation flow path 23 is opened and the recirculation pump 9 is activated. Return to 1. The opening / closing control of the switching valves 12, 13, 15 and the control of the water supply pump 7 and the recirculation pump 9 are automatically controlled by a control device (not shown).

The water temperature in the steam separator 3 is the pressure of the steam system (about 10MP
Although the saturation temperature is 310 ° C. determined by a), the water temperature from the feed water heater 8 is considerably lower than that, so the feed water temperature at the inlet of the steam generator 1 drops to around 170 to 200 ° C. At the time of reactor trip, the heat transfer area of the heat exchanger does not change from the rated state even if the load decreases in this way, so the heat transfer area becomes excessive compared to the heat exchange amount, and the secondary sodium outlet temperature is controlled by the feed water temperature. To be done. Therefore, the rated condition of 310
The temperature is 210 to 250 ℃, and there is a possibility that thermal shock will be applied to reactor cooling system equipment such as intermediate heat exchangers. When the reactor power reaches the decay heat level of about 1% of the rated state after a further lapse of time, the secondary sodium inlet temperature is about 330 ° C.
It goes down to around. In this case, since the water temperature is low, 2
The secondary sodium outlet temperature is almost equal to the feed water temperature and drops to around 200 ° C.

On the other hand, if the supply water flow rate is also reduced to about 6% of the rated state in accordance with the flow rate on the secondary sodium side, the decrease in the secondary sodium outlet temperature can be controlled. However, due to the decrease in water supply, a part of the evaporation pipe 2 is a water single phase, and the other is a water / steam two phase
In another part, it is separated from the steam single phase, and the distribution state of water and steam is different in the pipe, which causes unstable conditions such as vibration, and the temperature of the tube plate supporting the steam pipe 2 is increased. Because of the difference, the integrity of the steam generator may be compromised. When the plant is restarted after the reactor trip, the secondary sodium temperature has dropped considerably due to the stable state, so to raise the temperature to the rated state again,
It will take a considerable amount of time.

The conventional example using the recirculation method has been described above.
Even if the drain heat exchange method is adopted, the feed water temperature does not rise sufficiently. Therefore, it is difficult to maintain the sodium temperature sufficiently high in the high-temperature standby mode operation in the integrally flow-through type steam generator adopting the conventional method. still,
Related to this type of steam generation plant, "Proceding of the IAE Internation"
al Synposium on LMEBR Development) No.6-9, 1984,
TOKYO Japan is known.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and a first object and a second object of the present invention are a steam generator capable of performing a high temperature standby mode operation and mitigating a thermal shock applied to a reactor cooling facility. To provide a plant.

[Outline of Invention]

In the steam generator plant of the present invention, the secondary sodium is circulated inside by a secondary sodium pump, and a vapor having an evaporation pipe whose both ends are respectively connected to the water supply passage and the vapor passage is built in the steam generator plant. A generator, a steam separator provided in the steam passage, and steam from the steam separator are turned into water through a first steam passage switching valve, a turbine, a condenser, and a deaerator. The water supply flow path, which is circulated and supplied in communication via a water supply pump, a water supply heater and a water supply flow path switching valve,
A recirculation flow passage having a recirculation flow passage switching valve communicating the feed water heater, the feed water flow passage switching valve downstream position and the water separator bottom, and a steam flow passage downstream of the steam separator. And a steam flow path provided with a second steam flow path switching valve that branches from the steam flow path upstream of the first steam flow path switching valve and communicates with the condenser downstream of the turbine. The first feedwater pump, the first and second steam flow passage switching valves, the feedwater flow passage switching valve, and the recirculation flow passage switching valve are automatically controlled based on a reactor trip signal. The steam flow path switching valve and the feed water flow path switching valve are closed, the second steam flow path switching valve and the recirculation flow path switching valve are opened to supply feed water to the steam generator, and a reactor trip is performed. Immediately after that, the secondary sodium In the one provided with a control device for switching to a loop configuration of a sodium sensible heat removal mode for cooling secondary sodium having a high temperature close to the rated temperature flowing into the steam generator from the pump, the feed water passage downstream of the feed water heater A spray equipped with a spray nozzle switching valve that is controlled by the control device that branches from the water supply flow path at a position between the switching valve and the spray nozzle that is connected to the spray nozzle disposed in the upper portion of the water / water separation. A first feature is that a nozzle water supply flow path and a recirculation pump provided in the recirculation path are provided, and secondary sodium is circulated inside by a secondary sodium pump and A steam generator having an evaporation pipe whose both ends are respectively connected to a water supply channel and a steam channel, a steam separator disposed in the steam channel, and the steam The steam from the separator is turned into water through the steam flow switching valve, turbine, condenser, and deaerator in order, and is circulated and supplied through the water supply pump, the water heater, and the water flow switching valve. And a recirculation passage provided with a recirculation passage switching valve that communicates the feed water heater, the feed water passage switching valve downstream position and the bottom of the steam separator, and the feed pump based on a reactor trip signal A control device for automatically controlling the steam flow path switching valve, the feed water flow path switching valve, and the recirculation flow path switching valve, the switching valve communicating the turbine and the feed water heater. And a first bypass steam flow path provided with a steam flow path switching valve of the steam flow path, which is formed in communication with the turbine downstream of the steam separator and provided with the steam flow path switching valve. A second bypass steam flow passage provided with a switching valve that connects the upstream side of the lube, the turbine, and the feed water heater to the downstream side of the switching valve of the first bypass steam flow passage, and the feed water heating. And a second bypass steam flow passage communicating between the condenser and the condenser, and a second switching valve that communicates between the bottom side of the steam separator and the deaerator.
Of the recirculation flow path and the feed water flow path switching valve downstream of the feed water heater, branching from the water supply flow path and communicating with a spray nozzle arranged in the upper part of the steam separator. The sodium temperature attached to the spray nozzle water supply passage to which the spray nozzle switching valve controlled by the control device is attached and the secondary sodium type hot leg connected to the steam generator is detected, and the detected sodium temperature is When the temperature is equal to or lower than the set temperature, the control device opens the switching valve provided in the second recirculation flow path and the feed water flow path switching valve downstream of the feed water heater, and the recirculation valve at the bottom of the steam separator is opened. The switching valve provided in the circulation flow path and the spray nozzle water supply flow path is closed to supply the supply water to the steam generator, and the secondary sodium is supplied immediately after the reactor trip. Pump color From the loop configuration of the sodium sensible heat removal mode for cooling the secondary sodium having a high temperature close to the rated temperature flowing into the steam generator, the switching valve provided in the second recirculation flow path and the downstream of the feed water heater. The water supply passage switching valve is closed, the recirculation passage at the bottom of the steam separator and the switching valve provided in the spray nozzle water supply passage are opened, and spray water is sprayed into the steam separator. Supply to the steam generator after heat exchange with steam in the steam separator, cool secondary sodium at a temperature lower than the rated temperature flowing into the steam generator from the secondary sodium pump, and A second feature is that a thermocouple that emits a signal to switch to a decay heat removal mode loop configuration that removes decay heat of a nuclear reactor equivalent to several percent or less of output is provided.

That is, in the present invention, during the reactor trip, the supply water from the feed water heater is sprayed from the spray nozzle in the steam separator by the opening / closing operation of the valve provided in the piping system to exchange heat with the steam in the steam separator. Water is supplied to the steam generator at the saturation temperature on the water side (about 300 ° C). Thereby, the decay heat can be removed according to the output change of the nuclear reactor, and the secondary sodium output temperature can be maintained at the water side saturation temperature.

Example of Invention

In the following, the steam generator plant of the present invention is used in the embodiment, the same parts as those of the conventional one are denoted by the same reference numerals, and the description of the structure of the same part is omitted.
It will be described with reference to the drawings. FIG. 1 is an explanatory diagram. In the figure, 27 is a water supply passage, which is branched from the upstream side of the water supply passage switching valve 14 downstream of the water supply heater 8 and upstream of the connection position of the recirculation passage 23 of the water supply passage 22. It communicates with a spray nozzle 29 arranged at the upper part of the container 3. Water supply channel
A switching valve 28 is provided at 27. In the drawings, the black and white symbols indicate that the valves are closed and the white ones are open.

In the above configuration, when the reactor trips, the secondary sodium pump 26 is stopped and the pony motor operation is started by the reactor trip signal, so that the secondary sodium flow rate decreases to 6% of the rated state. Also on the steam side, the reactor reduces the rotational speed of the feed water pump 7 by a trip signal, and reduces the flow rate to 20% of the rated state so as not to cause an unstable state in the steam generator 1. At the same time, the switching valve 12 is closed, the switching valve 13 is opened, and the switching valve 14 is closed and the switching valve 28 is opened as in the conventional case.

The amount of heat exchanged in the steam generator 1 greatly decreases as the secondary sodium flow rate decreases. Therefore, at the outlet of the evaporation pipe 2, saturated steam in which two phases of water and steam are mixed is formed, and the steam separator 3 is used.
To The steam separated by the steam separator 3 has a steam flow path 17
From the steam turbine 18 to the turbine 4 side, but since the switching valve 12 is closed, the steam passage 18 directly reaches the condenser 5 and condenses.
The condensed water has its dissolved gas removed by the deaerator 6 and is pressurized by the feed water pump 7 to reach the feed water heater 8. Water heater 8
Since the switching valve 14 is closed for the water supply heated by,
It is guided to the upper part of the steam separator 3 from the water supply channel 27 and sprayed into steam from the spray nozzle 29. The sprayed feed water exchanges heat with steam, then merges with the saturated water in the steam separator 3, is pressurized by the recirculation pump 9, and flows into the steam generator 1 from the feed water passage 22. The pressure of this steam system is 10
The pressure is maintained at 10 MPa by the pressure control valve 11, and the saturation temperature at this pressure is 310 ° C.

In the conventional example, the feed water from the feed water heater 8 directly merges with the saturated water in the steam separator 3 in the feed water passage 22, so that the steam generator 1 is heated to 170 to 200 ° C., which is considerably lower than the saturation temperature. It is supplied with water. However, in the present embodiment, since the feed water from the feed water heater 8 is sprayed in the steam separator 3 and heat-exchanged with the steam and then merges with the saturated water in the steam separator 3, the saturated water near the saturation temperature is obtained. The feed water temperature can be raised to a temperature higher than the conventional example of about 300 ° C. That is, at the time of reactor trip, the heat transfer area in the heat exchanger is excessive compared to the amount of heat exchanged, so the secondary sodium outlet temperature is dominated by the feed water temperature. However, in this embodiment, since the feed water temperature can be raised to near 300 ° C., the secondary sodium outlet temperature also does not drop below this feed water temperature, and
Does not change rapidly compared to 310 ° C.

Since the secondary sodium outlet temperature can be maintained near the water side saturation temperature like steam, it is possible to operate in a high temperature standby mode in a steam generator that has a recirculation method in an integrated flow type. Further, since the outlet temperature of the secondary sodium does not change suddenly, it is possible to mitigate the thermal shock applied to the reactor coolant equipment such as the intermediate heat exchanger. Note that when the plant is restarted after the reactor trip, the opening of the switching valve 14 and the switching valve 28 can be adjusted to change the flow rate sprayed to the steam separator 3, so that the output of the reactor The feed water temperature can be controlled according to the change.

As described above, the steam generator plant of the present embodiment is a one-flow type plant in which a recirculation method is added to spray the feed water heated by the steam generator during the reactor trip from the steam generator into the steam water separator. It has a structure to supply heat to the steam generator from the water supply channel after exchanging heat with the steam from the steam generator, so it is possible to operate in the high temperature standby mode where the secondary sodium outlet temperature does not drop too much from the rated time. Become. Further, since the change in the secondary sodium outlet temperature is small, the thermal transient condition concerning the reactor cooling system is relaxed, and the soundness of the reactor plant equipment is improved. Further, since the operation in the high temperature standby mode can be performed, the time until the reactor is restarted after the trip is shortened and the operation of the reactor plant becomes easy.

2 to 4 show another embodiment, FIG. 2 shows the rated operation state, and FIG. 3 shows the sodium sensible heat removal mode (since the Na temperature is high, the sensible heat mode is used. 4) and FIG. 4 is an explanatory view showing the decay heat removal mode. In FIG. 2, the switching valve 13, the steam flow path 18 and the recirculation pump 9 which have been used conventionally and in the above-described embodiment are omitted. Instead, a steam flow path 34 having a steam flow path switching valve 31 connecting the steam turbine 4 and the feed water heater 8 downstream side, a steam flow path 35 connecting the feed water heater 8 upstream side and the condenser 5, A recirculation flow path 36 having a switching valve 32 connecting the steam separator 3 and the deaerator 6, a steam flow path
17 is provided with a steam passage 33 that branches from the upstream side of the switching valve 12 and is connected to the steam passage 34 on the downstream side of the switching valve 31. still,
The water supply passage 27 to the steam separator 3, the switching valve 28, and the spray nozzle 29 are the same as those in the above embodiment. Then, the flow paths on the steam side, the water supply side, and the recirculation side are switched. In addition, a thermocouple 37 was used to measure the secondary sodium inlet temperature.
Is installed in the secondary sodium-based Hottreg 24.

Next, the operation will be described. FIG. 2 shows the rated operation state.
Secondary sodium is from the secondary sodium-based Hottreg 24,
It flows in at a rated flow rate at a temperature of 475 ° C. Then, it exchanges heat with the steam flowing in the shell side of the steam generator 1 and flowing in the evaporation pipe 2, and after falling to 310 ° C., it is boosted from the secondary sodium cold leg 25 by the secondary sodium pump 26 to intermediate heat exchange. Return to the container (not shown). On the other hand, switching valves 15, 28,
Since 30, 32 are closed, the feed water heated to 210 ° C. by the feed water heater 8 is distributed to the evaporation pipe 2 at the rated flow rate and exchanges heat with secondary sodium, and becomes heated steam at 455 ° C. and becomes the steam flow path 16
It reaches the steam separator 3. After that, the superheated steam is in the steam flow path.
The steam turbine 4 is driven to rotate through 17. A part of this steam is extracted and flows from the steam flow path 34 to the feed water heater 8. After being used for heating the feed water, it reaches the condenser 5 from the steam flow path 35 and joins with the steam from the steam turbine 4. In the condenser 5, the steam is condensed by a large amount of cooling water, the dissolved gas is removed by the deaerator 6, and the pressure is increased by the feed water pump 7 to reach the feed water heater 8.

In the rated state, the loop is constructed as described above, but when the reactor trips, the valve opening / closing is controlled by the control device based on the reactor trip signal, and the loop construction is switched to the sodium sensible heat removal mode loop construction shown in FIG. On the secondary sodium side, the secondary sodium pump 26 has stopped and the operation has shifted to pony motor operation, and the flow rate is 6% of the rated value.
The secondary sodium inlet temperature is maintained at the rated state of 475 ° C for a while because the temperature change in the high temperature plenum inside the reactor is gentle. In order to remove the sensible heat of the secondary sodium, the steam side takes the following measures. First, the rotational speed of the feed water pump 7 is reduced by the reactor trip signal to reduce the flow rate to 20% of the rated state, and at the same time, the switching valves 12 and 31 are closed and the switching valves 30 and 32 are opened.

Since the amount of heat exchanged in the steam generator 1 is greatly reduced due to the decrease in the flow rate of the secondary sodium, at the outlet of the evaporation pipe 2, saturated steam in which two phases of water and steam are mixed is returned to the steam separator 3. The steam separated in the steam separator 3 reaches the feed water heater 8 directly from the steam passages 33, 34 because the switching valves 12, 31 heading from the steam passage 17 to the turbine 4 side are closed. After exchanging heat, it flows into the condenser 5 from the steam passage 35 and is condensed. The saturated water separated in the steam separator 3 is
Since the switching valve 15 is closed and the switching valve 32 is opened, the recirculation flow path 36 reaches the deaerator 6. After that, it reaches the feed water heater 8 through the feed water passages 20 and 21 as in the rated state. The feed water temperature at the inlet of the feed water heater 8 is 160 ° C.
When the amount of heat exchanged in the secondary sodium sensible heat removal mode is about 8% of the rated state, the heat exchange with the steam from the steam flow path 34 causes the feed water temperature to be 275 ° C., which is 70% less than the conventional example. It can be higher than ℃.

Since the water is supplied to the steam generator 1 at the water supply temperature of 275 ° C, the secondary sodium outlet temperature does not drop below this temperature and does not change rapidly from the rated state of 310 ° C. further,
A signal based on the secondary sodium inlet temperature measured by the thermocouple 37 installed in the secondary sodium-based hot-leg 24 when the atomic path output decreases and the decay heat removal level of 6 to 1% of the rated state is reached. The valve opening is controlled by the switch to switch to the decay heat removal mode loop configuration shown in FIG.
On the secondary sodium side, as in the above-mentioned sodium sensible heat removal mode, the operation is on the pony motor side and the flow rate is 6% of the rated value, but since the temperature of the high temperature plenum inside the reactor has already dropped, the secondary sodium The inlet temperature has dropped to around 335 ° C.

On the steam side, on the other hand, the rotation speed of the water supply pump 7 for removing the decay heat is further reduced, and the flow rate is reduced to 10% of the rated value at which instability does not occur. When the secondary sodium inlet temperature measured by the thermocouple 37 provided in the secondary sodium-based hot-leg 24 becomes equal to or lower than the set temperature (temporarily 350 ° C.), the switching valves 14 and 32 are closed and the switching valve 15 is closed. Open 28. As a result, the water supply flow path and the recirculation flow path are switched, and the water is supplied to the steam generator 1 in this procedure. Since the switching valve 14 is closed, the feed water heated by the steam in the feed water heater 8 is guided to the upper portion of the feed water separator 3 from the feed water passage 27 and then sprayed from the spray nozzle 29 to the steam in the feed water separator 3. To be done. The feed water that has exchanged heat with the steam joins the saturated water in the steam separator 3 and reaches the steam generator 1 from the recirculation flow path 23. And the steam separated by the steam separator 3 is
Steam flow path 17,3 similar to the sodium sensible heat removal mode of steam
After passing through 3, 34 and 35, the water is condensed in the condenser 5, and reaches the feed water heater 8 from the deaerator 6 and the feed water pump 7.

As described above, in the decay heat removal mode, the feed water is sprayed into the steam in the steam separator 3 and, after heat exchange with the steam, merges with the saturated water in the steam separator 3, so the inlet of the steam generator 1 The feed water temperature in the section can be raised to about 300 ° C, which is near the saturation temperature. As a result, the outlet temperature of the secondary sodium that exchanges heat with the steam generator 1 does not drop below the feed water temperature, so that the integrated once-through steam generator can be operated in the high temperature standby mode. In the present embodiment, it is possible to control the valve opening / closing of the steam system and switch the loop configuration by the reactor output or the secondary sodium inlet temperature.

FIG. 5 shows a flow chart for switching the operation mode. The rating is determined by the presence or absence of the reactor trip signal and the comparison of the secondary sodium inlet temperature measured by the thermocouple 37 and the set temperature. Operation mode, sodium sensible heat removal mode, decay heat removal mode, reactor output and 2
The operation that adapts to the change in the secondary sodium inlet temperature can be performed, and the rapid transient change in the secondary sodium outlet temperature can be suppressed, and the thermal shock applied to the reactor cooling system equipment can be mitigated. Further, in the decay heat removal mode of the present embodiment, since the sensible heat of sodium is not removed, the recirculation amount can be small, and a sufficient height difference between the steam separator 3 and the inlet of the steam generator 1 can be secured. Therefore, it is possible to supply water using natural circulation, the recirculation pump 9 can be eliminated as compared with the conventional example and the above-mentioned example, and the sensible heat mode operation in the state where the Na temperature is high is followed by the decay heat removal mode operation. The valve can be operated continuously by controlling the valve opening / closing operation, and has the same effect as that of the above embodiment.

〔The invention's effect〕

As described above, in the steam generator plant of the present invention, it is possible to operate in the high temperature standby mode by the integrated flow-through type recirculation system, and to have the effect of mitigating the thermal shock applied to the reactor cooling equipment. .

[Brief description of drawings]

1 and 2 respectively show different embodiments of the steam generator plant of the present invention. FIG. 1 is an explanatory diagram of a reactor trip state, FIG. 2 is an explanatory diagram of a rated operating state, FIG. Fourth
FIG. 5 is an explanatory diagram of the state after changing from the state of FIG. 2 to the sodium sensible heat removal mode and the decay heat removal mode, respectively, and FIG. 5 is a flow chart showing the operation mode switching of FIGS. 2 to 4, and FIG. The figure is an explanatory view of a reactor trip state of a conventional steam generation plant. 1 ... Steam generator, 2 ... Evaporation tube, 3 ... Steam separator,
4 ... Turbine, 5 ... Condenser, 6 ... Deaerator, 7 ...
Water supply pump, 8 ... Water supply heater, 9 ... Recirculation pump,
12,13,14,15,28,30,31,32 …… Switching valve, 16,17,18,3
3,34,35 …… Steam flow path, 22,27 …… Water supply flow path, 23,36 ……
Recirculation flow path, 24 ... Secondary sodium-based hot-leg, 29 ...
… Spray nozzle, 37… thermocouple.

Claims (2)

[Claims] 1. A steam generator in which secondary sodium is circulated internally by a secondary sodium pump, and inside of which an evaporation pipe having both ends respectively connected to a water supply flow path and a steam flow path is incorporated, A steam separator disposed in the steam flow path, and steam from the steam separator is turned into water through a first steam flow path switching valve, a turbine, a condenser, and a deaerator in order to become a water supply pump, The water supply flow path, which is circulated and supplied through the water supply heater and the water supply flow path switching valve, and the water supply heater,
A recirculation flow passage to which a recirculation flow passage switching valve that communicates the downstream position of the feed water flow passage switching valve and the bottom of the steam separator is attached, and the steam passage downstream of the steam separator. A first steam flow path switching valve, a steam flow path provided with a second steam flow path switching valve that branches from the steam flow path upstream and communicates with the condenser downstream of the turbine, and a reactor trip. Based on a signal, the water supply pump, the first and second steam flow path switching valves, the water supply flow path switching valve, and the recirculation flow path switching valve are automatically controlled to switch the first steam flow path. The valve and the feed water flow path switching valve are closed, the second steam flow path switching valve and the recirculation flow path switching valve are opened to supply the feed water to the steam generator, and the upper air is supplied immediately after the reactor trip. Above secondary sodium pump In the one provided with a controller for switching to a loop configuration of a sodium sensible heat removal mode for cooling secondary sodium having a high temperature close to the rated temperature flowing into the steam generator, the feed water flow path switching valve downstream of the feed water heater and And a spray nozzle water supply passage to which a spray nozzle switching valve, which is branched from the water supply passage at a position between the two and communicates with a spray nozzle disposed in the upper part of the steam separator, and which is controlled by the control device, And a recirculation pump provided in the recirculation flow path, the steam generator plant. 2. A steam generator in which secondary sodium is circulated inside by a secondary sodium pump, and a steam pipe having both ends connected to a feed water passage and a steam passage is built in the inside of the steam generator. , A steam separator disposed in the steam flow path, and steam from the steam separator is turned into water through a steam flow path switching valve, a turbine, a condenser, and a deaerator in order to become a water supply pump, water heating Recirculation flow passage switching valve that communicates the water supply flow passage that is circulated and supplied through the water supply device and the water supply flow passage switching valve, the feed water heater, the downstream position of the water supply flow passage switching valve, and the bottom of the steam separator. A recirculation flow path to which is attached, based on a reactor trip signal, the water supply pump, the steam flow path switching valve, the water supply path switching valve,
And a control device for automatically controlling the recirculation flow passage switching valve, wherein the turbine and the feed water heater are in communication with each other, and a first bypass steam flow passage provided with a switching valve, The first passage connecting the steam passage switching valve upstream side of the steam passage having the steam passage switching valve formed in communication with the turbine downstream of the water separator and the turbine and the feed water heater. By-pass of the second bypass steam passage provided with a switching valve for communicating between the downstream side of the switching valve of the flow passage and the third bypass steam communicating between the feed water heater and the condenser. A flow path, a second recirculation flow path provided with a switching valve for communicating between the bottom side of the steam separator and the deaerator, and the feed water flow path switching valve downstream of the feed water heater. From the water supply channel at the position between A spray nozzle water supply passage having a spray nozzle switching valve which is connected to a spray nozzle disposed in the upper portion of the steam separator and is controlled by the control device, and 2 connected to the steam generator. The sodium temperature is attached to the next sodium type hot leg, and when the detected sodium temperature is equal to or lower than the set temperature, the control device causes the switching valve provided in the second recirculation flow path and the feed water heater downstream. The feed water flow path switching valve is opened, and the switching valves provided in the recirculation flow path at the bottom of the steam separator and the spray nozzle feed water flow path are closed to supply the feed water to the steam generator, Immediately after the trip, sodium that cools the high temperature secondary sodium near the rated temperature flowing into the upper air steam generator from the upper air secondary sodium pump Due to the loop configuration of the heat removal mode, the switching valve provided in the second recirculation passage and the water supply passage switching valve downstream of the feedwater heater are closed, and the recirculation passage at the bottom of the steam separator is Open the switching valve provided in the spray nozzle water supply flow path, spray the feed water in the steam separator, and after supplying heat to the steam in the steam separator, supply to the steam generator, Loop of decay heat removal mode that cools secondary sodium having a temperature lower than the rated temperature flowing into the steam generator from the secondary sodium pump to remove decay heat of the reactor corresponding to several percent or less of the rated output A steam generator plant, which is provided with a thermocouple that emits a signal that switches to a configuration.